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MRCP: Infectious Diseases > Zoonotic / Parasites / Protozoa > Flashcards

Zoonotic / Parasites / Protozoa Flashcards

1
Q

What is the bacteria behind Lyme disease?

A

Borrelia Burgdorfei

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2
Q

What are the early features of Lyme disease?

A

Early features (within 30 days)
- Erythema migrans
‘bulls-eye’ rash is typically at the site of the tick bite
headache
lethargy
fever
arthralgia

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3
Q

How does erythema migrains develop in Lyme disease?

A

Typically develops 1-4 weeks after the initial bite
more than 5 cm in diameter and slowly increases in size
present in around 80% of patients.
systemic features

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4
Q

What are later features of Lyme disease?

A

Heart block
Perimyocarditis

Facial nerve palsy
Radicular pain
Meningitis

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5
Q

How is Lyme disease diagnosed?

A

Can be diagnosed clinically if erythema migrans is present

First line investigation: enzyme-linked immunosorbent assay (ELISA) antibodies to Borrelia burgdorferi are the first-line test

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6
Q

What should you do if you Lyme ELISA is negative, but still consider possible diagnosis?

A

Repeat ELISA in 4-6 weeks time

If over 12 weeks an immunoblot should one completed

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7
Q

How should Lyme disease be treated?

A
  1. Doxycycline
  2. Amoxicillin (as an alternative - i.e. if pregnant)

Ceftriaxone if disseminated disease

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8
Q

What is a Jarisch-Herxheimer reaction?

A

After initiating therapy: fever, rash, tachycardia after first dose of antibiotic (more commonly seen in syphilis, another spirochaetal disease)

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9
Q

What are the two forms of trypanosomiasis?

A

African trypanosomiasis (sleeping disease)
American trypanosomiasis ( Chagas disease)

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10
Q

How does trypanosomiasis spread?

A

Tsetse fly

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11
Q

What are that cause of African trypanosomiasis?

A

Trypanosoma gambiense in West Africa
Trypanosoma rhodesiense in East Africa

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12
Q

What are the features of African trypanosomiasis (sleeping disease) ?

A

Trypanosoma chancre - painless subcutaneous nodule at site of infection
intermittent fever
Enlargement of posterior cervical lymph nodes

Later:
central nervous system involvement e.g. somnolence, headaches, mood changes, meningoencephalitis

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13
Q

How do you treat African trypanosomiasis?

A

early disease: IV pentamidine or suramin

later disease or central nervous system involvement: IV melarsoprol

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14
Q

What is the cause of chagas disease?

A

Trypanosoma cruzi.

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15
Q

What is the classification of trypanosomiasis?

A

trypanosomiasis is a protozia

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16
Q

How does Chagas disease present?

A

95% asymptomatic in acute early phase
Chagoma - erythematous nodule at site of infection
periorbital oedema
Myocarditis –> dilated cardiomyopathy (chronic)
GI: Megaoesphagus, megacolon
causing dysphagia and constipation

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17
Q

What is the treatment of Chagas disease?

A

Acute:
azole or nitroderivatives such as benznidazole or nifurtimox

chronic disease management involves treating the complications

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18
Q

How should Malaria be investigated?

A

Thick blood film - most sensitive for diagnosis
Thin blood film - diagnosis of species

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19
Q

What other features do you seen on a blood count of malaria?

A

Thrombocythaemia is characteristic
Normochromic normocytic anaemia
Normal white cell count
Reticulocytosis

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20
Q

What type of organism is toxoplasmoisis Gondi?

A

intracellular protozoan

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21
Q

How do you manage toxoplasmosis in immunocompetent patients?

A

Does not require treatment unless severe infection / immunocompromised

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22
Q

What is the treatment of toxoplasmosis? And when do you treat?

A

pyrimethamine plus sulphadiazine for at least 6 weeks

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23
Q

Congenital toxoplasmosis. How is it acquire? Presentation?

A

Congenital toxoplasmosis is due to transplacental spread from the mother. It causes a variety of effects to the unborn child including

Neurological damage:
- cerebral calcification
- hydrocephalus
- chorioretinitis

Ophthalmic damage
- retinopathy
- cataracts

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24
Q

What are the features of severe malaria falciparum ?

A

Schizonts on a blood film
Parasitaemia > 2%
Hypoglycaemia
Acidosis
Temperature > 39 °C
Severe anaemia

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25
Q

What are the complications of malaria?

A

Cerebral malaria: seizures, coma
Acute renal failure: blackwater fever, Secondary to intravascular haemolysis, mechanism unknown
Acute respiratory distress syndrome (ARDS)
Hypoglycaemia
Disseminated intravascular coagulation (DIC)

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26
Q

What is the treatment of malaria falciparum?

A

First line therapy:
Artemisinin + combination

Artemether plus lumefantrine
Artesunate plus amodiaquine
Artesunate plus mefloquine
Artesunate plus sulfadoxine-pyrimethamine
Dihydroartemisinin plus piperaquine

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27
Q

What is the treatment of severe malaria falciparum?

A

Intravenous artesunate

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28
Q

How are people infected with Strongyloides stercoralis?

A

Infected larvae in soil gain access by penetrating the skin

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29
Q

What are the features of Strongyloides stercoralis?

A

Diarrhoea
Abdominal pain/bloating
Papulovesicular lesions on soles of feet and buttocks
Larva currens: pruritic, linear, urticarial rash

If the larvae migrate to the lungs a pneumonitis similar to Loeffler’s syndrome may be triggered

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30
Q

What is the shape of Strongyloides larvae?

A

rhabditiform larvae.

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31
Q

What is the treatment for strongyloides?

A
  1. Ivermectin (best)
  2. Albendazole

Ivermectin is a single dose agent
Albendazole require multiple doses

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32
Q

What causes”thread worm” and what are its features?

A

Enterobius vermicularis / Pin worm

Perianal itching
Assymtomatic in 90%

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33
Q

How is thread worm investigated?

A

sticky plastic tape to the perianal area and sending it to the laboratory for microscopy to see the eggs

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34
Q

How do you treat thread worm ?

A

Bendazoles

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35
Q

What causes hookworm?

A

Ancylostoma duodenale

Necator americanus

36
Q

What are the features of hookworm?

A

Larvae penetrate skin of feet; gastrointestinal infection → anaemia

Thin-shelled ova

37
Q

What are the features of loa loa?

A

auses red itchy swellings below the skin called ‘Calabar swellings’, may be observed when crossing conjunctivae

38
Q

How is loa loa transmitted?

A

Deer fly
Mango fly

39
Q

What is the treatment of loa loa?

A

Diethylcarbamazine

40
Q

What are the features of trichnerella spirals?

A

Features include fever, periorbital oedema and myositis (larvae encyst in muscle)

41
Q

How is trichnerella spiralis treated?

A

Bendazoles

42
Q

What is river blindness? How is it spread?

A

Onchocerca volvulus

Spread by female black flies

43
Q

How is onchocera volvulus treated?

A

Ivermeticin
rIVERblindness
= Ivermeticin

44
Q

What are the features of Amoebiasis?

A

Profuse blood diarrhoea

  • there is a long incubation period
45
Q

How is amoebiasis tested?

A

“Hot stool test” - test for stool within 15 minutes
stool microscopy may show trophozoites if examined within 15 minutes or kept warm (known as a ‘hot stool’) - otherwise moves into cyst form and not easily diagnosed

46
Q

How is amoebiasis treated?

A

Metronidazole

invasive amoebiasis should be followed by a luminal amoebicide to eradicate the cystic stage which is resistant to metronidazole and tinidazole/diloxanide furoate (which are used against the invasive stage)

47
Q

What type of organism is rickettsia?

A

Gram-negative obligate intracellular parasites

48
Q

What diseases does rickettsia cause?

A

Rocky Mountain spotted fever
- Rickettsia ricketsii

Q fever
-Coxiella burnetti

Enedemic typhus
- Rickettsia typhus and rickettersia prowazekki

49
Q

What is the organism and vector for Rocky Mountain spotted fever?

A

Tick

Rickettsia ricketsii

50
Q

What is the organism and vector for Q fever?

A

Coxiella Brunetti

There is no vector

51
Q

What is the organism and vector for endemic typhus?

A

Rickettsia prowazekii - Human body louse
Rickettsia typhi - Flea

52
Q

How is rickettsia treated?

A

Tetracyclines

53
Q

What is the bacteria behind leptospirosis?

A

Leptospira interrogans

54
Q

What is the vector for leptospirosis?

A

Infective rat urine

People get it in:
- Sewage worker
- Farmers
- Vets
- Abbatoir workers

55
Q

What is Weil’s disease? What causes it?

A

Leptospirosis
Always consider in hepatorenal failure

Early phase is due to bacteraemia and lasts around a week:
-Mild or subclinical
- Fever
- Flu-like symptoms
- Subconjunctival suffusion (redness)/haemorrhage

Second immune phase may lead to more severe disease (Weil’s disease):
- Acute kidney injury (seen in 50% of patients)
- Hepatitis: jaundice, hepatomegaly
- Aseptic meningitis

56
Q

How should leptospirosis be investigated?

A

Serology: antibodies to Leptospira develop after about 7 days
PCR
Culture

57
Q

What is treatment for leptospirosis?

A

high-dose benzylpenicillin or doxycycline

58
Q

What is the presentation of rickettsia typhus? ricketsii? and conorii?

A

Typhus: Black eschar at site of original inoculation
rash e.g. maculopapular or vasculitis
complications: deranged clotting, renal failure, DIC

Rickettsia: macular rash or hands and feet then spreads

Conorii: rash initially in axilla then spreads

59
Q

What is the causative organism in cat scratch disease?

A

Gram negative rod Bartonella henselae

60
Q

What are the features of cat scratch disease?

A

Features
fever
history of a cat scratch
regional lymphadenopathy
headache, malaise

61
Q

What are the features of Q fever?

A

typically prodrome: fever, malaise
causes pyrexia of unknown origin
transaminitis
atypical pneumonia
endocarditis (culture-negative)

62
Q

Treatment for Q fever?

A

Doxycycline

63
Q

What are the features of brucella?

A

non-specific: fever, malaise
hepatosplenomegaly
sacroiliitis: spinal tenderness may be seen
complications: osteomyelitis, infective endocarditis, meningoencephalitis, orchitis
leukopenia often seen
Wet hay smell of sweat

64
Q

What is the treatment of brucella?

A

Doxycycline and streptomycin

65
Q

What stain is used on bartonella?

A

Warthin-Starry staining

66
Q

Most common bacteria from animal bites?

A

Pasteurella multocida.

67
Q

How best to treat animal bites?

A
  1. Metronidazole

If allergic:
Doxycycline + metrondiazole

68
Q

How are human bites treated?

A

Co-amoxiclav

69
Q

What are the features of cutaneous leishmaniasis?

A

Crusted lesion at site of bite
May be underlying ulcer

70
Q

What cause cutaneous leishmaniasis?

A

Leishmania tropica
Leishmania mexicana

71
Q

What is the difference between South or Central American cutaneous leishmaniasis and Africa /Indian cutaneous leishmaniasis?

A

South / Central America required treatment due to risk of mucocutaneous Leishmaniasis

72
Q

What causes mucocutaneous leishmaniasis?

A

Leishmania braziliensis

73
Q

What causes visceral leishmaniasis?

A

Leishmania donovani

74
Q

What causes visceral leishmaniasis?

A

fever, sweats, rigors
massive splenomegaly. hepatomegaly
poor appetite*, weight loss
grey skin - ‘kala-azar’ means black sickness
pancytopaenia secondary to hypersplenism

75
Q

How should visceral leishmaniasis be diagnosed?

A

Bone marrow aspirate
or
Splenic biopsy

76
Q

What bacteria are found in human bites?

A

Streptococci spp.
Staphylococcus aureus
Eikenella
Fusobacterium
Prevotella

Risk of Hep C and HIV should be considered

77
Q

How is brucella diagnosed? How is it stained?

A

Brucella serology

Rose Bengal plate test can be used for screening but other tests are required to confirm the diagnosis

78
Q

What are the features of blackwater fever?

A

Large intravascular haemolysis resulting in haemoglobinuria
Anaemia
Jaundice
Acute kidney injury.

Urine is classically black or dark red in colour

79
Q

What are the most common non falciparum malarias?

A

Plasmodium vivax - Central America / India
Plasmodium ovale - Africa
Plasmodium malariae

80
Q

What are the features of Plasmodium vivax/ovale?

A

Cyclical fever every 48 hours

+ General malaria features:
- Fever
- Splenomegally
- Headache

81
Q

What are the features of Plasmodium malariae?

A

General malaria features:
- Fever
- Splenomegally
- Headache

Nephrotic syndrome

82
Q

What is treatment for non-falciparum Marla?

A

WHO recommend either an artemisinin-based combination therapy (ACT) or chloroquine

In areas which are known to be chloroquine-resistant an ACT should be used

ACTs should be avoided in pregnant women
patients with ovale or vivax malaria should be given

Primaquine following acute treatment with chloroquine to destroy liver hypnozoites and prevent relapse

83
Q

How can toxoplasmosis present in immunocompetent individuals?

A

Acute toxoplasmosis in the immunocompetent patient can mimic acute EBV infection (low-grade fever, generalised lymphadenopathy with prominent cervical lymph nodes and malaise) and should be suspected with negative EBV serology. Pregnancy testing and counselling is paramount due to the risk of congenital toxoplasmosis

84
Q

Look at malaria prophylaxis table

A

Looks at malaria prophylaxis takle

85
Q

What infection do you get from rabbits?

A

Tularaemia is a zoonotic infection involving the microorganism F. tularensis

produces an erythematous papulo-ulcerative lesion at the site of the bite with reactive and ulcerating regional lymphadenopathy.

86
Q

How do you treat F. tularensis ?

A

Doxycycline

87
Q

Why is Plasmodium knowlesi difficult to treat?

A

P. knowlesi has the shortest erythrocytic replication cycle, leading to high parasite counts in short periods of time

MRCP: Infectious Diseases (15 decks)

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