Microbiology 3 Flashcards

Question

what is the diagnosis of histoplasmosis?

Answer 1

- culturing the fungi (e.g. from sputum) or by demonstrating them on histological secretions - H. capsulatum glycoprotein can be detected in urine and serum in those with acute pulmonary and disseminated infection - antibodies usually develop within 3 weeks of the onset of illness and are best detected by complement fixation or immunodiffusion (sensitivity of 95% and 90%)

Answer 2

in urine and serum in those with acute pulmonary and disseminated infection

Answer 3

antibodies usually develop within 3 weeks of the onset of illness and are best detected by complement fixation or immunodiffusion (sensitivity of 95% and 90%)

Answer 4

95% and 90%, respectively

Answer 5

- only symptomatic acute pulmonary histoplasmosis, chronic histoplasmosis and acute disseminated histoplasmosis require treatment - itraconazole is effective in mild-moderate disease - severe infection treated with IV amphotericin B for 1-2 weeks followed by itraconazole for 12 weeks or with voriconazole - methylprednisolone for respiratory complications - AIDS: parenteral amphotericin B followed by maintenance therapy with itraconazole 200mg BD where HAART unavailable - surgical excision of histoplasmomas or chronic cavitatory lung lesions or adhesions following mediastinits are often required

Answer 6

Histoplasma duboisii (spores larger than H. capsulatum)

Answer 7

- skin lesions (e.g. abscesses, nodules, lymph node involvement and lytic bone lesions) are prominent - pulmonary lesions do not occur - treatment similar to that for H. capsulatum infection

Answer 8

one of several species of dimorphic fungi of the genus Aspergillus - A. fumigatus is most common - A. flavus and A. niger are also recognised

Answer 9

- ubiquitous in the environment and are commonly found on decaying leaves and trees - infection by inhalation of the spores - disease manifestation depends on dose of the spores inhaled and the immune response of the host

Answer 10

dose of spores inhaled and immune response of the host

Answer 11

- bronchopulmonary allergic aspergillosis - aspergilloma - invasive aspergilllosis

Answer 12

- yeast like fungus Cryptococcus neoformans | - worldwide distribution

Answer 13

birds, esp. pigeons, in their droppings

Answer 14

spores gain entry into the body through the respiratory tract, where they elicit a granulomatous reaction

Answer 15

- pulmonary symptoms are uncommon - meningitis is usual mode of presentation and often develops subacutely; HIV infection or lymphoma - lung cavitation, hilar lymphadenopathy, pleural effusions and occasionally pulmonary fibrosis - skin and bone involvement is rare

Answer 16

- demonstrating organisms in appropriately stained tissue sections - positive latex cryptococcal agglutinin test performed on CSF is diagnostic of cryptococcosis

Answer 17

- liposomal amphotericin B alone or in combination with flucytosine for 2 weeks is followed by oral fluconazole 400mg OD - therapy continued for 8 weeks if meningitis present - fluconazole may be used

Answer 18

- has greater CSF penetration - used when toxicity is encountered with amphotericin B and flucytosine - as maintenance therapy in immunocompromised patients, esp. those with HIV

Answer 19

non-budding spherical form (spherule) of Coccidioides immitis - soil saprophyte - found in southern USA, Central America and parts of South America

Answer 20

inhalation of thick-walled barrel-shaped spores called arthrospores - epidemics of coccidioidomycosis have been documented after dust storms

Answer 21

- most are asymptomatic - acute pulmonary coccidioidomycosis presents after an incubation of 10 days - fever, malaise, cough and expectoration - erythema nodosum, erythema multiforme, phlyctenular conjunctivitis and pleural effusions may occur - pulmonary cavitation with haemoptysis, pulmonary fibrosis, meningitis lytic bone lesions, hepatosplenomegaly, skin ulcers and abscesses in severe disease

Answer 22

- respiratory secretions - can be cultured in specialist labs - serological test: latex agglutination and precipitin tests (IgM); positive within 2 weeks of infection and decline after - complement fixation, ELISA and radioimmunoassay - complement fixation test (IgG) on CSF is diagnostic of coccidioidomycosis meningitis; positive within 4-6 weeks

Answer 23

conversion of a skin test using coccidiodin (extract from a culture of mycelial growth of C. immitis) from negative to positive

Answer 24

extract from a culture of mycelial growth of C. immitis

Answer 25

- mild pulmonary infections are self limiting and need no treatment - progressive and disseminated disease needs urgent therapy - ketoconazole, itraconazole or fluconazole for 6 months is used for primary pulmonary disease - more prolonged courses for cavitating or fibronodular disease - fluconazole in high dose (600-1000mg daily) for meningitis - voriconazole and posaconazole for poor response - surgical excision of cavitatory pulmonary lesions or localised bone lesions may be needed

Answer 26

systemic infection caused by biphasic fungus Blastomyces dermatitidis - in North America, South America, India and Middle East

Answer 27

- involves skin: non-itchy papular lesions that later develop into ulcers with red verrucous margins - ulcers initially confined to exposed parts of the body but later involve unexposed parts as well - atrophy and scarring may occur - pulmonary involvement presents as a solitary lesion resembling a malignancy or gives rise to radiological features similar to TB - fever, malaise, cough and weight loss - bone lesions common and present as painful swelling

Answer 28

- organism is demonstrated in histological sections or by culture - results can be negative in 30-50% of cases - enzyme immunoassay may be helpful, but there is some cross-reactivity of antibodies to blastomyces with histoplasma

Answer 29

- itraconazole for mild to moderate disease in the immunocompetent for up to 6 months - ketoconazole or fluconazole also used - amphotericin B indicated in severe or unresponsive disease and in the immunocompromised

Answer 30

- invasive zygomycosis - rhinocerebral mucormycosis - subcutaneous zygomycosis - other forms

Answer 31

- rare - caused by several fungi, including Mucor spp., Rhizopus spp. and Absidia spp. - severely ill patients - vascular invasion with marked haemorrhagic necrosis

Answer 32

- most common form of Mucormycosis - nasal stuffiness, facial pain and oedema and necrotic, black nasal turbinates - rare - mainly seen in diabetics with ketoacidosis

Answer 33

brawny, woody infiltration involving the limbs, neck and trunk and rarely the pharynx and orbital regions in immunosuppressed patients

Answer 34

pulmonary and disseminated infection (immunosuppressed) and GI infection (in malnutrition)

Answer 35

- amphotericin B and sometimes judicious debridement | - oral saturated postassium iodide has been used in subcutaneous variety

Answer 36

- caused by saprophytic fungus Sporothrix schenckii | - found worldwide

Answer 37

- infection usually follows cutaneous inoculation - at site of inoculation, a reddish, non-tender, maculopapular lesion develops (plaque sporotrichosis) - pulmonary involvement and disseminated disease rarely occur

Answer 38

occurs at site of cutaneous inoculation with Sporothrix schenckii; reddish, non-tender, maculopapular lesion develops

Answer 39

itraconazole 100-200mg/day for 3-6 months is usually curative

Answer 40

- disease seen in the tropics | - caused by several filamentous fungi of the Basidobolus genus

Answer 41

- usually remains confined to the subcutaneous tissues and muscle fascia - presents as a brawny, woody infiltration involving the limbs, neck and trunk - pharyngeal and orbital regions affected in immunocompromised patients and poorly controlled diabetes mellitus (less common) - locally erosive - may be fatal

Answer 42

- amphotericin B | - saturated potassium iodide solution given orally

Answer 43

- caused by fungus of various genera including Phialophora, Wangella and Fonsecaea - found in tropical and subtropical countries

Answer 44

- initially as a small papule, at site of previous injury - papule persists for months before ulcerating - later becomes warty and encrusted and gradually spreads - satellite lesions may be present - itching

Answer 45

- amphotericin B combined with itraconazole or voriconazole | - cryosurgery used to remove local lesions

Answer 46

- subcutaneous infection with fungi (Eumycetes spp.) or bacteria - confined to tropics

Answer 47

- local swelling which may discharge through sinuses | - bone involvement may follow

Answer 48

surgical debridement, combined with antimicrobials chosen according to the aetiological agent

Answer 49

- P. jiroveci is homologous with fungi | - associated with immunodeficiency states, esp. AIDS

Answer 50

- chronic fungal infections of keratinous structures such as the skin, hair or nails - Trichophyton spp., Microsporum spp., Epidermophyton spp. and Candida spp. can also infect keratinous structures

Answer 51

- Malassezia spp. are found on the scalp and greasy skin - responsible for seborrhoeic dermatitis, pityriasis versicolor (hypo- or hyperpigmented rash on trunk) and Malassezia folliculitis (itchy rash on back)

Answer 52

topical antifungals or oral ketonazole if infection is refractory or more extensive

Answer 53

- sporozites that aren't destroyed by immune response are taken up by the liver and multiply inside hepatocytes as merozoites - infected hepatocytes rupture, releasing merozoites into blood where they're taken up by erythrocytes

Answer 54

- P. vivax and P. ovale stay dormant in the liver as hypnozoites - may reactivate at any time subsequently, causing relapsing infection

Answer 55

multiply, changing from merozoite, to trophozoite, to schizont and finally appearing as 8-24 new merozoites - erythrocyte ruptures, releasing the merozoites to infect further cells

Answer 56

48hrs in P. falciparum, P. vivax and P. ovale | 72hrs in P. malariae

Answer 57

- P. vivax and P. ovale attack reticulocytes and young erythrocytes - P. malariae attacks older cells - P. falciparum parasitizes any stage of erythrocyte

Answer 58

- haemolysis of infected red cells - haemolysis of non-infected red cells (blackwater fever) - dyserythropoiesis - splenomegaly and sequestration - folate depletion

Answer 59

non-immune individuals; e.g. children in area, adults in hypoendemic areas and any visitors from non-malarious region

Answer 60

10-21 days, but can be longer

Answer 61

- fever - general malaise, headache, vomiting or diarrhoea - fever may be continual or erratic; classical tertian or quartan fever only appears after a few days - temp reaches 41 - rigors and drenching sweats

Answer 62

- usually mild illness (P. vivax can cause severe disease) - anaemia develops slowly and may be tender hepatosplenomegaly - spontaneous recovery in 2-6 weeks - hypnozoites in liver can cause relapses - repeated infections cause chronic ill health due to anaemia and hyperreactive splenomegaly

Answer 63

- mild illness - runs a more chronic course - parasitaemia may persist for years, with or without symptoms - associated with glomerulonephritis and nephrotic syndrome in children

Answer 64

- causes self-limiting illness - may cause serious complications; most deaths are due to this - high parasitaemia indicates severe disease - cerebral malaria and blackwater fever

Answer 65

>1% of red cells infection

Answer 66

- marked by diminished consciousness, confusion and convulsions - often progress to coma and death - untreated it's universally fatal

Answer 67

- due to widespread intravascular haemolysis due to malaria | - affects both parasitised and unparasitised red cells, giving rise to dark urine

Answer 68

tropical splenomegaly syndrome/hyperreactive malarial splenomegaly - seen in older children and adults in hyperendemic areas - associated with exaggerated immune response to repeated malria infections - anaemia, massive splenomegaly and elevated IgM levels - malaria parasites are absent/scanty - usually respond to prolonged treatment with prophylactic antimalarial drugs

Answer 69

- presenting with febrile illness in, or having left, a malarious area - falciparum malaria unlikely to present more than 3 months after exposure, even if patient has been taking prophylaxis - vivax malaria may cause symptoms up to a year later

Answer 70

- identifying parasites on a Giemsa-stained thick or thin blood film - 3 films should be examined before malaria is declared unlikely - rapid antigen detection test for near-patient use - serological tests are of no diagnostic value - lumbar puncture may be needed to exclude bacterial infection - overdiagnosed in endemic areas

Answer 71

- prostration | - cerebral malaria (coma convulsion = 3 seizures in 24hrs)

Answer 72

- haemoglobinuria (blackwater fever) - oliguria - uraemia (serum creatinine >250umol/L) (acute tubular necrosis)

Answer 73

- severe anaemia (<50g/L) (haemolysis and dyserythropoiesis) - disseminated intravascular coagulation (DIC) - bleeding e.g. retinal haemorrhages

Answer 74

- tachypnoea | - acute respiratory distress syndrome

Answer 75

- hypoglycaemia (<2mmol/L) (esp. in children) | - metabolic acidosis (blood pH <7.25)

Answer 76

- diarrhoea - jaundice (bilirubin >50umol/L) - splenic rupture

Answer 77

- shock; hypotensive and Gram-negative septicaemia | - hyperpyrexia

Answer 78

- chloroquine 600mg, 300mg 6hrs later, 300mg 24hrs later and 300mg 24hrs later OR ACT for 3 days - plus primaquine 15mg for 2-3 weeks

Answer 79

- ACT 3 days OR quinine + doxycycline 7 days | - plus primaquine 0.75mg/kg single dose

Answer 80

1st trimester: quinine + doxycycline 7 days | 2nd/3rd trimester: ACT 3 days

Answer 81

- ACT 3 days; appropriate dose for body weight | - plus primaquine 0.75mg/kg single dose

Answer 82

atovaquone-proguanil or quinine + doxycycline 7 days

Answer 83

artemisinin-based combination therapy | - recommended oral treatment for uncomplicated falciparum malaria worldwide

Answer 84

- presence of any complications | - parasite count above 1% in a non-immune patient

Answer 85

- IV artesunate is more effective than IV quinine and should be used when possible; absorption from IM injection is less reliable than from IV injection - intensive care facilities may be needed, including mechanical ventilation and dialysis - severe anaemia may need transfusion - careful monitoring of fluid balance is essential; pulmonary oedema and prerenal failure are common - hypoglycaemia can be induced by infection and by quinine treatment - superadded bacterial infection is common

Answer 86

- artemether-lumefantrine: 4 tablets BD for 3 days - artesunate-amodiaquine: 4mg/kg per day artesunate for 3 days - dihydroartemisin-piperaquine: 4mg/kg per day dihydroartemisinin for 3 days

Answer 87

- artesunate-mefloquine: 4mg/kg per day artesunate for 3 days - artesunate-sulfadoxine-pyrimethamine: 4mg/kg per day artesunate for 3 days

Answer 88

- artesunate + clindamycin: 2mg/kg per day + 10mg/kg BD for 7 days - artesunate + doxyclycline: 2mg/kg per day + 3.5 mg/kg per day for 7 days

Answer 89

1. aggressive control in highly endemic countries, to reduce mortality and decrease transmission 2. progressive eradication at the endemic margins, to shrink the malaria map 3. research into new vaccines, new drugs, new diagnostics and better ways of delivering malaria care

Answer 90

parasitaemia >10%

Answer 91

- combination of case treatment - vector eradication - personal protection from vector bites, e.g. insecticide (permethrin) treated nets

Answer 92

- insecticides - house spraying with DDT - manipulation of habitat (e.g. marsh drainage)

Answer 93

diethyltoluamide, DEET, 20-50% in lotions and sprays

Answer 94

1. IV artesunate 2. IV quinine 3. IM artesunate 4. IM artemether 5. rectal artesunate

Answer 95

immediate: 2.4mg/kg subsequent: 2.4mg/kg at 12 and 24hrs, then daily (up to 7 days)

Answer 96

immediate: 20mg/kg subsequent: 10mg/kg 8 hourly (up to 7 days)

Answer 97

immediate: 2.4mg/kg subsequent: 2.4mg/kg at 12 and 24hrs, then daily (up to 7 days)

Answer 98

immediate: 3.2mg/kg subsequent: 1.6mg/kg daily

Answer 99

immediate: 10mg/kg subsequent: transfer to centre where parenteral therapy available

Answer 100

- chloroquine 300mg weekly | - alternative: proguanil 200mg daily

Answer 101

- chloroquine 300mg weekly + proguanil 200mg daily | - alternative: doxycycline 100mg daily OR malarone 1 tablet daily OR mefloquine 250mg weekly

Answer 102

- mefloquine 250mg weekly | - alternative: doxycycline 100mg daily OR malarone 1 tablet daily

Answer 103

African trypanosomiasis

Answer 104

- caused by trypanosomes transmitted to humans by bite of the tsetse fly (genus Glossina) - endemic in a belt across sub-Saharan Africa, extending to 14N and 20S (natural range of tsetse fly)

Answer 105

- Tryanosoma bruceigambiense (Gambian sleeping sickness) | - Trypanosoma b. rhodesiense (Rhodesian sleeping sickness)

Answer 106

Trypsanosoma bruceigambiense

Answer 107

T. b. rhodesiense

Answer 108

- found from Uganda in Central Africa, west to Senegal and south as far as Angola - man is major reservoir and infection is transmitted by riverine Glossina species (e.g. G. palpalis)

Answer 109

- occurs in East and Central Africa from Ethiopia to Botswana - zoonosis of both wild and domestic animals - maintained in game animals and transmitted by savanna flies e.g. G. morsitans - epidemics usually related to cattle and vectors are riverine flies

Answer 110

- Tsetse flies bite during the day and both males and females take blood meals - an infected insect may deposit metacyclic trypomastigotes (the infective form of the parasite) into the subcutaneous tissue - cause local inflammation (trypanosomal chancre) and regional lymphadenopathy - invade bloodstream within 2-3 weeks, then spread to all parts of the body including the brain

Answer 111

metacyclic trypomastigotes

Answer 112

local inflammation caused by metacyclic trypomastigotes

Answer 113

stage 1: pentamidine stage 2 (CNS): eflornithin + nifurtimox; eflornithine monotherapy (melarsoprol)

Answer 114

stage 1: suramin stage 2 (CNS): melarsoprol

Answer 115

- causes a chronic, slowly progressive illness - episodes of fever and lymphadenopathy occur over months or years and hepatosplenomegaly may develop - infection eventually reaches the CNS, causing headache, behavioural changes, confusion and daytime somnolence - progresses to tremors, ataxia, convulsions and hemiplegias - eventually coma and death

Answer 116

lymphocytic meningoencephalitis, with scattered trypanosomes visible in the brain substance

Answer 117

- more acute - early systemic features: myocarditis, hepatitis and serous effusions and patients can die before the onset of CNS disease - if they survive, cerebral involvement occurs within weeks of infection and is rapidly progressive

Answer 118

- may be seen on Giemsa-stained smears of thick or thin blood films, or of lymph node aspirate - blood films usually positive in T. b. gambiense; concentration techniques may increase the yield - serological tests useful for screening for infection - CATT is robust and easy to use field assay - examination of CSF

Answer 119

card agglutination test for trypanosomiasis

Answer 120

causes lymphocytosis and elevated protein in the CSF and parasites may be seen in concentrated specimens

Answer 121

South American trypanosomiasis

Answer 122

Chagas' disease

Answer 123

- caused by Trypanosoma cruzi - transmitted to humans in faces of bloodsucking reduviid bugs (cone-nose or assassain bugs) - faces infected with T. cruzi trypomastigotes are rubbed in through skin abrasions, mucosa or conjunctiva - bugs live in mud or thatch buildings, feed on vertebrate hosts at night, defecate

Answer 124

- spread in the bloodstream, before entering host cells and multiplying - cell rupture releases them back into the circulation, where they are taken up by a feeding bug - further multiplication takes place in the insect gut, completing the trypanosome life cycle - human infection can occur via contaminated blood transfusion or by transplacental spread

Answer 125

- usually in children - often passes unnoticed - firm reddish papule may be seen at site of entry, associated with regional lymphadenopathy - in conjunctival infection, there is swelling of the eyelid which may close the eye (Romana's sign) - fever, lymphadenopathy, hepatosplenomegaly and rarely, meningoencephalitis - may be fatal in infants - full recovery within weeks or months

Answer 126

- 10-30% of people go on to chronic disease after latent period - may be due to autoimmune response triggered by the initial infection - heart affected; conduction abnormalities, arrhythmias, aneurysm formation and cardiac dilation - GI involvement -> progressive dilation of parts of the GI tract -> megaoesophagus and megacolon

Answer 127

- trypanosomes seen on stained blood film during acute illness - in chronic disease, parasites may be detected by xenodiagnosis: infection-free reduviid bugs feed on patient and the insect gut examined for parasites - serological tests can detect acute and chronic Chagas' disease

Answer 128

- nifurtimox and benznidazole; effective in acute infection (cure rate of 90%), less effective in chronic disease - toxic with adverse reactions in up to 40% of patients - antiarrhythmic drugs and pacemakers may be needed in cardiac disease - surgical treatment for GI complications

Answer 129

- improved housing and living conditions - local vector control programmes - spraying houses with insecticide - impregnated bed nets with pyrethoid and insect repellents

Answer 130

- visceral leishmania - cutaneous leishmania - mucocutaneous leishmania

Answer 131

species complex - L. donovani species - L. donovani - L. infantum - L. chagasi

Answer 132

species complex - L. tropica - L. major - L. aethiopica - L. mexicana - L. braziliensis species - L. tropica - L. major - L. aethiopica - L. mexicana - L. amazonensis - L. garnhami - L. pifanoi - L. venezuelensis - L. braziliensis - L. guyanesis - L. panamanensis - L. peruviana

Answer 133

L. braziliensis

Answer 134

- caused by protozoa of the genus Leishmania - transmitted by bite of the female phlebotomine sandfly - seen in localised areas of Africa, Asia, Europe, the Middle East and South and Central America

Answer 135

- asymptomatic infection: parasite suppressed by a strong immune response; common in endemic areas (high incidence of positive skin tests) - symptomatic infection: combined to the skin or through the body (visceral) - relapse of previously asymptomatic infection is seen in patients who become immunocompromised

Answer 136

- parasites found as oval amastigotes (Leishman-Donovan bodies) - parasites multiply inside the macrophages and cells of the reticuloendothelial system and are released into the circulation as the cells rupture - parasites are taken into the gut of a feeding sandfly (genus Phlebotomus in Old World, Lutzomyia in New), wherre they develop into flagellate promastigote form - migrate to salivary glands of the insect, then inoculated into new host

Answer 137

- kala azar - caused by L. donovani, L. infantum or L. chagasi - prevalent in localised areas of Asia, Africa, Mediterranean and South America - incubation period usually 1-2 months, can be years - onset of symptoms is insidious - fever, enlargement of liver and spleen, lymphadenopathy, rough and pigmented skin, pancytopenia, wasting and immunosuppression - death within a year due to bacterial infection or uncontrolled bleeding

Answer 138

- demonstrating parasite in stained smears of aspirates of bone marrow, lymph node, spleen or liver - organism can be cultured from these specimens - specific serological tests are positive in 95% of cases - pancytopenia, hypoalbuminaemia and hypergammaglobulinaemia are common - leishmanin skin test is negative, indicating poor cell mediated immune response

Answer 139

- pentavalent antimony salts (e.g. sodium stibogluconate and meglumine antimoniate) - IV amphotericin B effective but expensive - IM paromomycin is cheaper and has good cure rate - miltefosine - combination therapy - PKDL

Answer 140

post-kala azar dermal leishmaniasis - skin eruption after successful treatment of visceral leishmaniasis - starts as a macular maculopapular nodular rash which spreads over the body - most often seen in Sudan and India - reports of it after miltefosine

Answer 141

number of geographically localised species which may be zoonotic or anthroponotic

Answer 142

- sandfly bite - leishmania amastigotes multiply in dermal macrophages - local response depends on species of leishmania, size of the inoculum and the host immune response - single or multiple painless nodules occur on exposed areas within 1 week to 3 months - nodules enlarge and ulcerate with a characteristic erythematous raised border - overlying crust may develop - lesions heal slowly over months or years

Answer 143

- Russia and Eastern Europe, Middle East, Central Asia, Mediterranean littoral and sub-Saharan Africa - reservoir for L. major is desert rodents - L. tropica has a mainly urban distribution with dogs and humans as reservoirs

Answer 144

- highlands of Ethiopia and Kenya | - animal reservoir is the hyrax

Answer 145

rare chronic relapsing form caused by L. tropica

Answer 146

Mexico, Guatemala, Brazil, Venezuela and Panama | - infection usually runs a benign course with spontaneous healing within 6 months

Answer 147

tropical South America | - infections heal spontaneously, but may take longer

Answer 148

- endemic area - Giemsa stain on a split-skin smear will demonstrate leishmania parasites in 80% of cases - biopsy tissue from edge of lesion can be examined histologically and parasites identified by PCR - leishmanin skin test positive in 90% of cases; doesn't distinguish between active and resolved infection - serology unhelpful

Answer 149

- small lesions usually require no treatment - large lesions or those in cosmetically sensitive sites can be treated locally, by curettage, cryotherapy or topical antiparasitic agents - systemic treatment may be needed

Answer 150

- 3-10% of infections with L. b. braziliensis - commonest in Bolivia and Peru - cutaneous sores are followed months or years later by indurated or ulcerating lesions affecting mucosa or cartilage, on lips or nose - may remain static - may be progression affecting nasopharynx, uvula, palate and upper airways

Answer 151

- biopsies show scanty organisms - parasites can be detected by PCR - serological tests frequently positive

Answer 152

- amphotericin B - systemic antimonial compounds - relapses are common - patients may die due to secondary bacterial infection or laryngeal obstruction

Answer 153

- relies on control of vectors/reservoirs of infection - insecticide spraying, control of host animals and treating infected humans - personal protection against sandfly bites - sandflies are poor fliers and sleeping off the ground helps prevent bites

Answer 154

- intracellular protozoan parasite Toxoplasma gondii - sexual form of the parasite lives in the gut of the definitive host, the cat, where it produces oocysts - after maturation, oocysts become source of infection for secondary hosts

Answer 155

man, cattle, sheep, pigs, rodents and birds | - disseminated infection

Answer 156

from contaminated cat faces, or by eating undercooked infected meat; transplacental infection may occur

Answer 157

when carnivorous felines eat infected animal tissue

Answer 158

in UK about 25%, rising to 90% in some parts of Europe

Answer 159

- most are asymptomatic or trivial - symptomatic patients: lymphadenopathy in head and neck, fever, myalgia, general malaise - hepatitis, pneumonia, myocarditis, choroidoretinitis - congenital toxoplasmosis: microcephaly, hydrocephalus, encephalitis, convulsions and mental retardation - affects immunocompromised aptients

Answer 160

- IgG antibodies detectable by Sabin-Feldman dye test remain positive for years - acute infection confirmed by demonstrating a rising titre of specific IgM

Answer 161

- acquired toxoplasmosis in an immunocompetent host rarely requires treatment - severe disease: sulfadiazine 2-4g daily and pyrimethamine 25mg daily given for 4 weeks, with folinic acid - infected infants treated from birth

Answer 162

- tick-borne parasitic disease - North America and Europe - zoonosis in rodents and cattle and may be transmitted to humans - infection more common in immunocompromised

Answer 163

plasmodium-like Babesia microti (rodents) and B. divergins (cattle)

Answer 164

around 10 days

Answer 165

- in patients with normal splenic function, illness is mild - in splenoctomised individuals, systemic symptoms are more pronounced and haemolysis is associated with haemoglobinuria, jaundice and acute kidney injury

Answer 166

examination of a peripheral blood smear may reveal the characteristic plasmodium-like organisms

Answer 167

- combination of quinine 650mg and clindamycin 600mg orally TDS for 7 days - atovaquone and azithromycin plus doxycycline used for persistent or relapsing disease

Answer 168

Amoebae - Entamoeba histolytica Flagellates - Giardia intestinalis Ciliates - Balantidium coli Coccidia - Cryptosporidium parvum - Isospora belli - Sarcocystis spp. - Cyclospora cayetanensis Microspora - Enterocytozoon bieneusi - Encephalitozoon spp.

Answer 169

Entamoeba histolytica

Answer 170

- E. histolytica (pathogen) - E. dispar (non-pathogenic) - E. moshkovskii (uncertain significance)

Answer 171

- identical - can be distinguished by molecular techniques after culture of the trophozoite - E. histolytica can be distinguished from all other amoebae and other intestinal protozoa by microscopic appearance

Answer 172

- motile trophozoite and as a cyst that can survive outside the body - cysts are transmitted by ingestion of contaminated food or water, or spread directly by person-to-person contact - trophozoites emerge from cysts in small intestine and pass to the colon, where they multiply

Answer 173

many individuals can carry the pathogen without obvious evidence of clinical disease

Answer 174

- E. histolytica trophozoites invade the colonic epithelium, with the aid of their own cytotoxins and proteolytic enzymes - parasites continue to multiply and finally frank ulceration of the mucosa occurs - if penetration continues, trophozoites may enter the portal vein, and reach the liver and cause intrahepatic abscesses

Answer 175

- incubation period is variable - usual course is chronic, with mild intermittent diarrhoea and abdominal discomfort - may progress to bloody diarrhoea with mucus and may have systemic symptoms e.g. headache, nausea and anorexia - infection may present as acute amoebic dysentry, resembling baillary dysentry or acute UC (less common)

Answer 176

- toxic dilatation of the colon - chronic infection with stricture formation - severe haemorrhage - amoeboma - amoebic liver abscess - tender hepatomegaly - high swinging fever - profound malaise

Answer 177

- microscopic examination of fresh stool or colonic exudate obtained at sigmoidoscopy - motile trophozoites containing erythrocytes must be identified - presence of amoebic cysts alone doesn't imply disease - sigmoidoscopy and barium enema may show colonic ulceration but aren't diagnostic - amoebic fluorescent antibody test is positive in 90% of patients with liver abscess and in 60-70% with active colitis - seropositivity low in asymptomatic cyst passers

Answer 178

- metronidazole 800mg TDS for 5 days (amoebic colitis) - lower dose (400mg TDS for 5 days) in liver abscess - tinidazole effective - bowel should be cleaned of parasites with a luminal amoebicide e.g. diloxanide furoate after treatment of invasive disease

Answer 179

- difficult to eradicate due to substantial human reservoir of infection - improved standards of hygiene, sanitation and better access to clean water - cysts are destroyed by boiling, but chlorine and iodine sterilizing tablets not always effective

Answer 180

- caused by Giardia intestinalis (flagellate) - small intestinal disease, with diarrhoea and malabsorption - prevalence high in developing countries and is most common parasitic infection in travellers returning to the UK - Europe and North america - person-to-person spread in day nurseries and residential institutions - exists as a trophozoite and cyst

Answer 181

- organism may colonise the small intestine and may remain there without causing detriment - severe malabsorption may occur and is related to morphological damage to the small intestine - mild partial villous atrophy; subtotal villous atrophy is rare - damage may be immune mediated - bacterial overgrowth has been found in association with giardiasis and may contribute to fat malabsorption

Answer 182

- many ingesting Giardia cysts have no symptoms - may become ill within 1-3 weeks after ingesting cysts - watery diarrhoea, nausea, anorexia, abdominal discomfort and bloating - symptoms usually resolve, but may persist - stools become paler, with features of steatorrhoea - weight loss

Answer 183

- cysts and trophozoites can be found in stool - negative stool examination doesn't exclude the diagnosis since parasite may be excreted at irregular intervals - parasite can be seen in duodenal aspirates (obtained at endoscopy or with a luminal capsule) and in histological sections of jejunal mucosa

Answer 184

- metronidazole 2g as a single does on three successive days - second/third dose may be needed - alternative drugs are tinidazole, mepacrine and albendazole

Answer 185

- organism found worldwide - cattle is major natural reservoir - demonstrated in supplies of drinking water in the UK - reproduces sexually and asexually - transmitted by oocysts excreted in the faeces

Answer 186

- self-limiting in healthy individuals - acute watery diarrhoea associated with fever and general malaise - lasts 7-10 days - severe and intractable diarrhoea in immunocompromised patients, esp. with HIV

Answer 187

- faecal microscopy; can be detected in intestinal biopsies | - no reliable treatment; nitazoxanide may benefit

Answer 188

- Balantidium coli; only ciliate that produces clinically significant infection in humans - found throughout the tropics, in Central and South America, Iran, Papua New Guinea and the Philippines - carried by pigs - most common in communities living closely with swine - identical lifecycle to E. histolytica

Answer 189

- diarrhoea and a dysenteric illness with invasion of the distal ileal and colonic mucosa - trophozoites rather than cysts are found in the stool - treatment with tetracycline or metronidazole

Answer 190

strictly anaerobic protozoan pathogen that inhabits the colon

Answer 191

- coccidian protozoal parasite - cause of diarrhoea in travellers to Nepal - has been detected in stool specimens from immunocompetent and immunodeficient people worldwide - infection is usually self-limiting - treated with co-trimoxazole

Answer 192

protozoa of the phylum Microsporea can cause diarrhoea in patients with HIV/AIDS

Answer 193

- largest internal human parasite - reproduce sexually, generating millions of eggs or larvae - nematodes and trematodes have a mouth and intestinal tract - cestodes absorb nutrients directly through the outer tegument - all worms are motile, however as adults they rarely migrate further - adult helminths live up to 30yrs

Answer 194

- tissue dwelling worms - intestinal human nematodes - zoonotic nematodes

Answer 195

Dracunculus medinensis

Answer 196

Ascaris lumbricoides

Answer 197

- Wuchereria bancrofti; filariasis - Brugia malayi/timori; filariasis - Loa loa; loiasis - Onchocerca volvulus; river blindness - Dracunculus medinensis; dracunculiasis - Mansonella perstans; mansonellosis

Answer 198

- Enterobius vernicularis; threadworm - Acaris lumbricoides; roundworm - Trichuris trichiura; whipworm - Necator americanus; hookworm - Ancylostoma duodenale; hookworm - Strongyloides stercoralis; strongyloidosis

Answer 199

- Toxocara canis; toxocariasis | - Trichinella spiralis; trichinellosis

Answer 200

- blood flukes - lung flukes - intestinal/hepatic flukes

Answer 201

Schistosoma species; causes schistosomiasis

Answer 202

Paragonimus species; paragonimiasis

Answer 203

- Fasciolopsis buski - Fasciola hepatica - Clonorchis sinensis - Opisthorchis felineus

Answer 204

intestinal adult worms and larval tissue cysts

Answer 205

- Taenia saginata; beef tapeworm - Taenia solium; pork tapeworm - Diphyllobothrium latum; fish tapeworm - Hymenolepis nana; dwarf tapeworm

Answer 206

- Taenia solium; cysticercosis - Echinococcus granulosus; Hyatid disease - Echinococcus multilocularis; Hyatid disease - Spirometra mansoni; sparganosis

Answer 207

- accidentally infect man and are not able to complete their normal life cycle - often become trapped in the tissues, causing a potentially severe local inflammatory response

Answer 208

- Filarioidea superfamily - adult worms are long and threadlike, from 2 to 50cm in length - females longer than males - larval stages inoculated into humans by various species of biting flies (each specific to a particular parasite)

Answer 209

- inoculated into humans by species of biting flies - adult worms develop from larvae mate - produce millions of offspring (microfilariae), which migrate in the blood or skin - ingested by feeding flies, where the remainder of the life cycle takes place

Answer 210

- may be caused by adult worms or by microfilariae | - caused by host immune response to the parasite and is characterised by massive eosinophilia

Answer 211

adult worms are long lived (10-15yrs) and reinfection is common; disease is chronic and progressive

Answer 212

- diethylcarbamazine (DEC) - ivermectin - albendazole - praziquantel

Answer 213

- loiaisis | - filariasis

Answer 214

- loiaisis - filariasis - onchocerciasis - strongyloidiasis

Answer 215

- filariasis (with DEC) | - intestinal helminths

Answer 216

schistosomiasis

Answer 217

- Wuchereria bancrofti - Brugia timori/malayi - Loa loa - Onchocerca - Mansonella perstans

Answer 218

``` adult worm: lymphatics microfilariae: blood major vector: Culex species clinical signs: fever, lymphangitis, elephantiasis distribution: tropics ```

Answer 219

adult worm: lymphatics microfilariae: blood major vector: Mansonia species clinical signs: fever, lymphangitis, elephantiasis distribution: East and South-east Asia, South India, Sri Lanka

Answer 220

``` adult worm: subcutaneous microfilariae: blood major vector: Chrysops species clinical signs: Calabar swellings, urticaria distribution: West and Central Africa ```

Answer 221

``` adult worm: subcutaneous microfilariae: skin, eye major vector: Simulium species clinical signs: subcutaneous nodules, eye disease distribution: Africa, South America ```

Answer 222

``` adult worm: retroperitoneal microfilariae: blood major vector: Culicoides species clinical signs: allergic eosinophilia distribution: Sub-Saharan Africa, South America ```

Answer 223

- by different mosquito species, mainly Culex fatigans - adult female worms (5-10cm long) live in lymphatics, releasing large numbers of microfilariae into the blood - occurs at night, so coinciding with nocturnal feeding pattern of C. fatigans

Answer 224

- transmitted by day-biting species | - found in South Pacific

Answer 225

- similar to W. bancrofti - nocturnal periodicity - Mansonia mosquitos

Answer 226

- larvae enter lymphatics and are carried to regional lymph nodes - grow and mature for 6-18 months - adult worms produce allergic lymphangitis - asymptomatic infection in endemic areas - early infection marked by bouts of fever with pain, tenderness and erythema along course of affected lymphatics - involvement of spermatic cord and epididymis common in Bancroftian filariasis - recurrent episodes cause intermittent lymphatic obstruction, which can become fibrotic and irreversible - obstructive lymphatics may rupture, causing cellulitis and further fibrosis - progressive enlargement, coarsening and fissuring of the skin, leading to elephantiasis - adult worms die, but lymphatic obstruction remains and tissue damage continues - microfilariae can be trapped in pulmonary capillaries, generating intense local allergic response; pneumonitis, cough, fever, weight loss and shifting radiological changes

Answer 227

high peripheral eosinophil count associated with pneumonitis caused by Filariasis

Answer 228

many years; only seen in association with recurrent infection in endemic areas

Answer 229

- detecting microfilariae in blood films or skin snips | - rapid and sensitive near-patient antigen detection tests

Answer 230

- DEC kills adult worms and microfilariae - serious allergic responses may occur as parasites are killed - mass treatment programmes using combinations of DEC, ivermectin and albendazole

Answer 231

- found in humid forests of West and Central Africa - caused by Loa loa; small (3-7cm filarial worm), found in subcutaneous tissues - microfilariae circulate in blood during day but cause no direct symptoms - vectors are day-biting flies of genus Chrysops

Answer 232

- adult worms migrate around the body in subcutaneous tissue planes - worms may be present for years w/out causing symptoms

Answer 233

- localised, tender, hot, soft tissue swellings occur due to hypoersensitivity (Calabar swellings) often near a joint; produced in response to passage of a worm - urticaria and pruitus - worm may be seen crossing eye under conjunctiva - may enter the retroorbital tissue; severe pain

Answer 234

- occur in Loiasis due to passage of a worm | - localised, tender, hot, soft tissue swellings occur due to hypoersensitivity, often near a joint

Answer 235

- microfilariae may be seen on stained blood films (often negative) - serological tests relatively insensitive and cross-react with other microfilariae - massive eosinophilia

Answer 236

- DEC may cause severe allergic reactions associated with parasite killing - ivermectin in single doses of 200-400ug/kg is effective; may cause severe reactions - albendazole may be used in heavily-infected patients - mass treatment with DEC or ivermectin can decrease transmission

Answer 237

- river blindness - 37 million people worldwide; 250k are blind and 500k visually impaired - West and Central Africa, small foci in Yemen and Central and South America - Onchocerca volvulus - day-biting flies of genus Simulium

Answer 238

- larvae inoculated by bite of infected fly - worms mature in 2-4 months, live more than 15 years - adult worms 50cm and <0.5mm diameter - live in subcutaneous tissues

Answer 239

- fibrotic nodules, esp. over bone and trauma sites - microfilariae distributed in skin; may invade eyes - live microfilariae cause little harm, dead parasites may cause severe allergic reactions, with hyaline necrosis and loss of tissue collagen and elastin - conjunctivitis, sclerosing keratitis, uveitis and secondary glaucoma, and choroidoretinitis - pruitus, urticaria and fleeting oedema - subcutaneous nodules, hypo/hyperpigmentation from excoriation and inflammatory changes - roughened, inelastic skin - hanging groin

Answer 240

- eosinophilia on blood film - skin snips taken from iliac crest or shoulder placed in saline under cover slip - after 4hrs, microscopy shows microfilariae - if this is negative, DEC applied topically under occlusive dressing; provokes an allergic rash (modified Mazzotti reaction) - slit lamp examination of eyes may show microfilariae

Answer 241

- used to diagnose Onchocerciasis - if microscopy is negative, DEC is applied topically under an occlusive dressing - provokes allergic rash in most infected people

Answer 242

Ivermectin, 150ug/kg - kills microfilariae and prevents return for 6-12 months - little effect on adult worms - annual retreatment is needed - in patients coinfected with Loa loa, it may induce severe allergic reactions, including toxic encephalopathy

Answer 243

Mansonella perstans - filarial worm - transmitted by biting midges of genus Culicoides - small numbers of microfilariae are in blood - don't cause serious disease - may be minor allergic reactions and an eosinophilia

Answer 244

Dracunculus medinensis (Guinea worm) - water fleas (copepods) containing the parasite larvae are swallowed in contaminated drinking water - ingested larvae mature and the female worm (up to 1m in length) migrates through connective and subcutaneous tissue for 9-18 months - surfaces on skin - uterus of worm rupture, releasing larvae which are ingested by small crustacean water fleas; cycle is completed

Answer 245

- extracting worm over several days by winding it round a stick - worm should not be damaged - antibiotics for secondary infection

Answer 246

- two main types of life cycle, both including a soil based phase - ingestion of eggs (require period of maturation in environment) OR - eggs hatch in soil and larvae penetrate directly through the skin of a new host

Answer 247

roundworm infection; Ascaris lumbricoides - pale yellow worm, 20-35cm long - found worldwide, common in poor rural communities with faecal contamination - larvae migrate through tissues to the lungs - expectorated and swallowed - adult worms are found in small intestine - ova are deposited in faeces and need 2-4 month maturation in soil before infected

Answer 248

- usually asymptomatic - heavy infections: nausea, vomiting, abdominal discomfort, anorexia - worms may obstruct small intestine, esp. at ileocaecal valve - may invade appendix, causing acute appendicitis, or bile duct, obstructing it and suppurative cholangitis - larvae in lung may cause pulmonary eosinophilia - heavy infection in children effects nutrition and development

Answer 249

- eggs identified in stool - adult worms may emerge from mouth or anus - barium enema studies

Answer 250

- piperazine, pyrantel pamoate, oxantel pamoate, albendazole, mebendazole, levamisole - surgical or endoscopic intervention for intestinal or biliary obstruction

Answer 251

- piperazine 75mg/kg - pyrantel pamoate 10mg/kg - oxantel pamoate 10mg/kg - albendazole 400mg - mebendazole 500mg - tiabendazole 25mg/kg - levamisole 2.5mg/kg - ivermectin 200ug/kg

Answer 252

Enterobius vermicularis - small (2-12mm) worm - common throughout world - larval development occurs in small intestine and adult worms are normally found in the colon - gravid female deposits eggs around the anus causing intense itching, esp. at night - do not need a maturation period in soil and infection often directly transmitted from anus to mouth via hands - eggs deposited on clothing and bed linen and are ingested/inhaled - usually harmless

Answer 253

- ova collected using moistened perianal swab - applying adhesive cellophane tape to perianal skin - identified by microscopy

Answer 254

- mebendazole and piperazine - isolated treatment of affected person often ineffective - other family members may need to be treated and advised about personal hygeine - two course of treatment 2 weeks apart may break cycle of autoinfection

Answer 255

Trichuris trichiura - common worldwide, esp. in poor communities with inadequate sanitation - adult worms are 3-5cm long - inhabit terminal ileum and caecum - found throughout large bowel in heavy infection - head of worm embedded in intestinal mucosa - ova deposited in faeces and require maturation period of 3-4 weeks in soil before becoming infective

Answer 256

usually asymptomatic, but mucosal damage may be so severe that there is colonic ulceration, dysentery or rectal prolapse

Answer 257

finding ova on stool microscopy, or by seeing adult worms on sigmoidoscopy

Answer 258

human hookworms Ancylostoma duodenale and Necator americanus - A. duodenale found mainly in East Asia, North Africa and Mediterranean - N. americanus found in South and Central America, South-east Asia and sub-Saharan Africa

Answer 259

- adult worms are 1cm long - live in the duodenum and upper jejunum (found in large numbers) - attach firmly to the mucosa using the buccal plate, feeding on blood - eggs passed in the faeces develop in warm moist soil, producing infective filariform larvae - filariform penetrate directly through the skin of a new host and are carried in the bloodstream to the lungs - cross the alveoli and parasites are expectorated and then swallowed, arriving at their definitive home

Answer 260

- local irritation as the larvae penetrate the skin (ground itch) - transient pulmonary signs and symptoms, with eosinophilia - light infections often asymptomatic - heavier worm loads associated with epigastric pain and nausea, esp. with malnourishment; may cause iron deficiency anaemia and hypoproteinaemia - heavy infection in children associated with delays in physical and mental development

Answer 261

finding eggs on faecal microscopy; in infections heavy enough to cause anaemia, they present in large numbers

Answer 262

- aim of treatment in endemic areas is reduction of worm burden rather than complete eradication - albendazole given as a single dose - WHO is promoting treatment programmes for school children in many parts of the world, with treatment of schistosomiasis where appropriate

Answer 263

Strongyloides stercoralis - small (2mm long) worm - lives in small intestine - found in many parts of the tropics and subtropics; esp. common in Asia

Answer 264

- eggs hatch in the bowel - larvae found in the stool - non-infective rhabditiform larvae - require further period of maturation in soil before becoming infective - maturation can occur in large bowel - infective filariform larvae can penetrate directly through the perianal skin, reinfecting the host - after skin penetration, life cycle is similar to hookworm - adult worms may burrow into intestinal mucosa, causing a local inflammatory response

Answer 265

- local dermatitis (in autoinfection, this manifests as a migratory linear weal around the buttocks and lower abdomen (cutaenous larva currens)) - heavy infections; damage to small intestinal mucosa causes malabsorption, diarrhoea and perforation - persistent eosinophilia - immunocompromised patients: filariform larvae may penetrate directly though the bowel wall, causing an overwhelming and usually fatal generalised infection - complicated by Gram-negative septicaemia due to bowel organsms

Answer 266

- occurs in immunosuppressed patients (by corticosteroids or intercurrent illness) - filariform larvae may penetrate directly through the bowel wall in huge numbers - causes an overwhelming and usually fatal generalised infection

Answer 267

- motile larvae seen on stool microscopy, esp. after incubation - serological tests - ivermectin (200ug/kg daily for 2 days) - albendazole (15mg/kg 12 hourly for 3 days)

Answer 268

Trichinella spiralis - normal hosts are pigs, bears and warthogs - humans infected by eating undercooked meat from these animals

Answer 269

- eating undercooked meat from pigs, bears and warthogs - ingested larvae mature in the small intestine - adults release new larvae which penetrate the bowel wall and migrate through the tissues - larvae encyst in striated muscle

Answer 270

- light infections usually asymptomatic - heavier loads of worms produce GI symptoms as adults establish themselves in the small intestine, followed by systemic symptoms as larvae invade - systemic symptoms: fever, oedema and myalgia - massive infection could be fatal

Answer 271

- clinical picture, associated eosinophilia and serological tests - muscle biopsy a few weeks after infection - albendazole (20mg/kg for 7 days) given early will kill adult worms and decrease load of larvae reaching the tissues - analgesia and steroids for symptomatic relief

Answer 272

Toxocara canis - dog roundworm - may be ingested by humans, esp. children

Answer 273

- eggs hatch and larvae penetrate small intestinal wall and enter the mesenteric circulation - unable to complete their life cycle in a foreign host - held up in liver capillaries, generating a granulomatous response - may migrate into lungs, striated muscle, heart, brain or eye

Answer 274

- infection usually asymptomatic; larvae die without causing serious problems - generalised symptoms (fever and urticaria) and eosinophilia, and focal signs in heavy infections - pulmonary involvement may cause bronchospasm and chest x-ray changes - ocular infection may produce granulomatous swelling mimicking retinoblastoma - cardiac or neurological involvement may be fatal

Answer 275

- isolation of larvae is difficult and diagnosis usually made serologically - albendazole 400mg daily (5-10mg/kg in children) for a week

Answer 276

cutaneous larva migrans

Answer 277

non-human hookworms Ancylostoma braziliense and A. canium

Answer 278

- hatch in warm moist soil and penetrate the skin - in man they're unable to complete a normal life cycle - migrate under the skin for days or weeks until death

Answer 279

- wandering of the larva accompanied by clearly defined, serpiginous, itchy rash; progresses 1cm per day - no systemic symptoms

Answer 280

- diagnosis purely clinical - single larvae treated with 15% solution of topical tiabendazole - multiple lesions treated with systemic therapy; single dose of albendazole 400mg or ivermectin 150-200ug/kg

Answer 281

- flukes - flat leaf-shaped worms - complex life cycles, often involving fresh water snails and intermediate mammalian hosts - disease caused by inflammatory response to eggs or to adult worms

Answer 282

- affects over 200 million people in the tropics and subtropics, mostly in sub-Saharan Africa - chronic infection causes significant morbidity - socioeconomic impact - disease of rural poor, but also with major development projects e.g. dams and irrigation schemes

Answer 283

- Schistosoma mansoni - S. haematobium - S. japonicum - S. mekongi - S. intercalatum

Answer 284

- eggs are passed in the urine or faces of an infected person and hatch in fresh water to release miracidia - ciliated organisms penetrate tissue of intermediate host, a species of water snail specific to each species of schistosome - multiply in snail, then fork-tailed cercariae are released back into the water, and survive for 2-3 days

Answer 285

- cercariae penetrate skin or mucous membranes of human - transform into schistosomulae - pass through lungs - reach portal vein, where they mature into adult worms (20+mm long) - worms pair in portal vein before migrating to final destination - remain in final destination for many years, producing many eggs, which are released in urine or faeces, or in the bladder, bowel wall, liver/distant sites

Answer 286

S. mansoni and S. japonicum: mesenteric veins S. haematobium: vesicular plexus

Answer 287

- local and systemic allergic reactions to migrating parasites in early stages - local inflammatory response in bowel or bladder when eggs are produced - ectopic eggs may produce granulomatous lesions anywhere in the body - chronic heavy infection (many eggs accumulate in the tissues); fibrosis, calcifications, dysplasia and malignant change - cerianal penetration may cause local dermatitis - symptom free period of 3-4 weeks - systemic allergic features: fever, rash, myalgia and pneumonitis (Katayama fever)

Answer 288

praziquantel 40mg/kg single dose

Answer 289

praziquantel 40mg/kg single dose

Answer 290

praziquantel 60mg/kg single dose

Answer 291

praziquantel 25mg/kg 8hrly for 3 days

Answer 292

praziquantel 25mg/kg 8hrly for 1-3 days

Answer 293

praziquantel 25mg/kg 8hrly for 1-3 days

Answer 294

praziquantel 25mg/kg 8hrly for 1 day

Answer 295

triclabendazole 10mg/kg single dose

Answer 296

- painless terminal haematuria - bladder inflammation progresses -> increased urinary frequency and groin pain - obstrucive uropathy -> hydronephrosis, CKD and recurrent urinary infection - association between chronic urinary schistosomiasis and squamous cell bladder carcinoma - genitalia may be affected - ectopic eggs may cause pulmonary or neurolgical disease

Answer 297

- affects large bowel - early disease produces superficial mucosal changes, with blood-stained diarrhoea - marked mucosal damage with rectal polyps, deeper ulceration and fibrosis and stricture formation - ectopic eggs carried to liver, where they cause intense granulomatous response - hepatitis followed by progressive periportal fibrosis -> portal hypertension, oesophageal varices and splenomegaly

Answer 298

- infects many mammals apart from man - infects large and small bowel - produces more eggs than S. mansoni - severe and rapidly progressive - hepatic involvement more common and neurological involvement in 5% of cases

Answer 299

- suggested by relevant symptoms following fresh water exposure in an endemic area - characteristic eggs (terminal spine in S. haematobium and lateral spine in other species) seen in microscopy - S. haematobium seen in a filtered mid-day urine sample, semen and rectal snips - S. mansoni and S. japonicum eggs found in faces or rectal snip 0 serological tests - xray, ultrasound and endoscopy may show abnormal bowel/urinary tract in chronic disease - liver biopsy may show periportal fibrosis

Answer 300

- aim in endemic areas is to decrease worm load and minimise chronic effects of egg deposition - may not be possible to eradicate adult worms completely - reinfection common - 90% reduction in egg output has been achieved in mass treatment programmes

Answer 301

many flukes infect man via ingestion of an intermediate host, often fresh water fish

Answer 302

Paragonimus - major species is P. westermani - adult worms live in the lungs, producing eggs which are expectorated or swallowed and passed in the faeces

Answer 303

- adult worms live in the lungs, producing eggs which are expectorated or swallowed and passed in the faeces - miracidia emerging from the eggs penetrate the first intermediate host, a fresh water snail - larvae released from snail, and encyst as metacercariae in fresh water crustacea - humans become infected after consuming uncooked shellfish - cercariae penetrate small intestinal wall and migrate directly from the peritoneum to lungs across the diaphragm

Answer 304

- humans become infected after consuming uncooked shellfish - cercariae penetrate small intestinal wall and migrate directly from the peritoneum to lungs across the diaphragm - establish themselves in lungs - can survive up to 20yrs

Answer 305

- fever - cough - mild haemoptysis - pneumonia or pulmonary TB - ectopic worms may cause signs in the abdomen or brain

Answer 306

- detection of ova on sputum or stool microscopy - radiological appearances are variable and nonspecific - treatment with praziquantel and avoidance of inadequately cooked shellfish

Answer 307

- Clonorchis sinensis - Opisthorchis felineus - O. viverrini

Answer 308

- adults live in bile ducts, releasing eggs into faeces - parasite requires two intermediate hosts, a fresh water snail and fish - humans infected by consumption of raw fish - cycle completed when excysted worms migrate from small intestine into bile ducts

Answer 309

- infection often asymptomatic, but may be associated with cholangitis and biliary carcinoma - diagnosis made by identifying eggs on stool microscopy - treatment with praziquantel and cooking fish adequately

Answer 310

- liver and intestinal flukes - require water snail as an intermediate host - cercariae encyst on aquatic vegetation and are consumed by animals or man - F. hepatica penetrates the intestinal wall before migrating to the liver - F. buski doesn't migrate causes mainly bowel symptoms

Answer 311

- tapeworms - ribbon-shaped worms - mm to several m in length

Answer 312

- adult worms live in intestine - attach to epithelium using suckers on anterior portion (scolex) - proglottids (progressively developing segments) arise from scolex - mature distal segments contain eggs and are released directly into faces or are carried out with an intact detached proglottid - eggs consumed by intermediate hosts - hatch into larvae (oncospheres) - penetrate intestinal wall of the host (pig or cattle) and encyst in the tissues

Answer 313

Taenia saginata - few if any symptoms - infection discovered when proglottids are found in faeces or on underclothing - praziquantel (10mg/kg)

Answer 314

Taenia solium - can reach 6m in length - South America, South Africa, China and South-east Asia

Answer 315

- ingestion of cysts of Taenia solium rather than the adult worm; follows ingestion of eggs from contaminated food or water - patients with tapeworms do not usually develop cysticercosis and patients with cysticercosis do not harbour tapeworms

Answer 316

cysts, 0.5-1cm in diameter, containing scolex of a new adult worm - common sites are subcutaneous tissue, skeletal muscle and brain

Answer 317

Diphyllobothrium latum - Europe and Japan - consumption of raw fish - no symptoms - megaloblastic anaemia (due to competetive utilisation of B12 by the parasite)

Answer 318

Echinococcus granulosus

Answer 319

- occurs when humans become an intermediate host of the dog tapeworm Echinococcus granulosus - adult worm lives in gut of domestic and wild canines - larval stages in sheep, cattle and camels - excyst, penetrate the small intestine wall and are carried to the liver - life cycle cannot be completed unless cyst is eaten by a dog

Answer 320

- depend on site of cyst - liver is most common organ affected, then lung, kidneys, brain and bone - pressure on bile ducts -> jaundice - rupture into abdominal cavity, pleural cavity or biliary tree - intermittent jaundice, abdominal pain, fever with eosinophilia - focal seizures if cysts in brain - renal involvement produces lumbar pain and haematuria - calcification of cyst - cyst rupturing into bronchus may result in expectoration and spontaneous cure

Answer 321

Echinococcus multilocularis

Answer 322

Diphyllobothrium latum

Answer 323

Hymenolepis nana

Answer 324

Taenia solium

Answer 325

- Echinococcus granulosus | - E. multilocularis

Answer 326

Spirometra mansoni

Answer 327

Trichinella spiralis

Answer 328

Toxocara canis

Answer 329

- Necator americanus | - Ancylostoma duodenale

Answer 330

- Wucheria bancrofti | - Brugia malayi/timori

Answer 331

Onchocerca volvulus

Answer 332

Dracunculus medinensis

Answer 333

Mansonella perstans

Answer 334

Enterobius vermicularis

Answer 335

Ascaris lumbicoides

Answer 336

Trichuris trichiura

Answer 337

Strongyloides stercoralis

Microbiology 3 Flashcards

(363 cards)