Microbial pathogens 2 Flashcards

Question

toxoplasmosis acute disease those most at risk

Answer 1

* Pregnant women and their unborn children * Those with weakened immune systems * Toxoplasmosis infection may lead to miscarriage, stillbirth or survival with growth problems, blindness, water on the brain (hydrocephalus), brain damage, epilepsy, or deafness. This often develops after birth, so even normally born infants of women with known infection should be kept under observation for some time.

Answer 2

-effects of congentical toxoplasmosis can be life long -coular disease -reactivation of dormant tissue cysts can occur -neuroloical effects

Answer 3

*As the host develops immunity the replication rate will slow and the infected host cells will become encapsulated (ie, tissue cysts). – These slowly replicating forms are called bradyzoites (brady means slow) and represent a dormant or resting stage. * Bradyzoites secrete chitin and other components to form a cyst wall

Answer 4

-associated with waning immunity (malignancies, transplantation and AIDs) -results from release of encysted organisms and the intitiation of te tachzoite stage of infection followed by tissue damage and inflammation

Answer 5

-occurs from activation of cysts deposited in or near the retina

Answer 6

-late 1994 and early 1995 outbreak of toxoplasmosis occured in a canadian community -serological evidence consistent with acute toxoplasmosis was demonstrated in 100 people -epidemiologic evidence implicated contamination of the city water supply withh oocysts

Answer 7

* Serologic testing IgG or IgM * Molecular testing eg PCR * Can detect parasite in biopsies * Ocular disease by case history and serologic testing

Answer 8

* The recommended treatment is the synergistic combination of pyrimethamine plus sulfadiazine. * Spiramycin for prophylactic use during pregnancy

Answer 9

-cooking meat to safe temps -wash fruit and veg -avoid drinking untreated water -wear gloves for gardening and wash hands afterwards -clean cat litter trays immedietly avoid if pregnant

Answer 10

-Toxovax® is intended for the prevention of toxoplasmosis abortion in ewes (may revert to pathogenic strain so not suitable for humans) -another type of vaccine that would be of grrat importance would be one administered to cats that could prevent or reduce the shedding of oocysts -oral vaccine was developed and validated for cats

Answer 11

– Host behavioural changes could benefit parasite – infected rodents are more likely to investigate novel stimuli and appear less cautious when presented with signs of cats. – hypothesised to increase the susceptibility of infected rodents to predation by cats, and therefore to increase the odds of completing the T. gondii life cycle.

Answer 12

– No adaptive benefit to parasite – Case-control studies show interesting correlations with human behaviours, mental health disorders and toxoplasma seropositivity * Schizophrenia, autism, risk-taking eg risk of traffic accident

Answer 13

* Felines are the definitive host for Toxoplasma gondii * Toxoplasma gondii causes chronic infections in up to one-third of the human population and in animals * In the immunocompromised patient or in the developing foetus, it can cause life-threatening infections with severe neurological and ocular manifestations * T. gondii observed to alter rodent psychology and studies suggest association with human behaviour

Answer 14

* The doubling time of slow-growing mycobacteria is no less than 16 hrs * Most are harmless environmental bacteria * A few have evolved as major human pathogens * M. tuberculosis * M. leprae * M. ulcerans

Answer 15

* Mycobacteria tuberculosis causes tuberculosis * World’s deadliest infectious disease * Mycobacteria leprae causes leprosy * Affects skin, nerves, eyes and respiratory tract * Documented in ancient literature * Mycobacteria ulcerans causes Buruli ulcer * Affects the skin and sometimes bone * can lead to permanent disfigurement and long-term disability

Answer 16

* Low infectious dose (1 cell) * Intracellular pathogens – in macrophage * Resistant cell wall * Subvert the human immune system * Mycobacterial cell surface components stop phagosome killing * Form characteristic granulomatous lesions * Immune cell cluster limiting mycobacterial invasion which mycobacteria can survive within * Slow-growing

Answer 17

-host immune cells fight infection by clustering into granuloma -mycobacteria are inside of macrophages in centre of granuloma -contained but surviving -suppressing phagosome killing -balance between host and pathogen varies

Answer 18

* Acid fast staining * NB neither Gram positive nor Gram negative * thick, waxy, hydrophobic cell envelope

Answer 19

* Resilient to most antibiotics * Drugs are available that treat mycobacterial infections * Resistance develops through mutation * Long term treatment with antibiotic mixtures necessary * The vaccine BCG offers partial protection, particularly to children * Vaccines work poorly due to immune evasion strategies of mycobacteria

Answer 20

* Some slow growing mycobacteria are intracellular pathogens * Unique features * Cell wall structure * Slow doubling time * Immune subversion * Major disease causing agents * Human tuberculosis * Leprosy * Buruli ulcer * Treatable but resistance to drugs a problem * Vaccine available- poor efficacy

Answer 21

a chronic infectious disease of the skin and nerves. * The main causal agent is Mycobacterium leprae * Symptoms are: * loss of sensation in hands and feet * leading to disability through injury * blindness. * Curable with multidrug treatment regimes

Answer 22

-one of the oldest and most stigmatised diseases -the stigma can result in rejection and exclusion (linked to widespread misunderstanding) -not highly contagious -typically caught via close contact over an extended period and is mainly spread through droplets from the nose and mouth by coughing -can be cured

Answer 23

remains endemic in central africa, southeast asia and south america -with more than 200000 new cases per year globally

Answer 24

-15,000 children were diagnosed -an estimated 2 to 3 million people with leprosy -countries with highest number of new diagnosis is india, brazil and indonesia -over half of new cases are in india -hoem to third of world's poor a group disporoportiannally affected by the disease

Answer 25

-in the USA they have been shown to transmit M.leprae to humans -strains are shared -respresents zoonotic resevoir

Answer 26

-possible zoonotic resevoir -only recently detected 2008 -non known squirrel-human transmission case

Answer 27

-affects skin and nerves symptoms are skin lesions, loss of sensation in hands and feet, disability through injury, blindness and nasal septum damage

Answer 28

-keratinocytes -nerve cells -dendritic cells -macrophages

Answer 29

-chronic granulomatous disease effecting teh skin and peripheral nerves -understanding of its pathogenesis and interaction with the human host is limited inability to culture the bacterium in vitro (some animal model organisms)

Answer 30

-95% of people show no symptoms (heritable) -within the 5% there are a range of symptoms -classified in spectrum from Tb to leprosy

Answer 31

-extensive sensory loss over a longer period -more severe disease and larger numbers of bacteria -facial deformaties and paralysis -involvement of eyes, bones and other tissues

Answer 32

cell-mediated immunity -macrophage activation humoral immunity -macrophage suppression and b cell stimulation

Answer 33

* antibody complex formation * the absence of granulomas * failure to restrain M. leprae growth. * robust antibody formation occurs but is not protective * cell-mediated immunity is conspicuously absent (eg activation of macrophages)

Answer 34

eatures Th1 T-cell cytokine response * vigorous T-cell responses to M. leprae antigen * containment of the infection in well-formed granulomas

Answer 35

M. leprae is an obligate intracellular pathogen with a distinct preference for Schwann cells of the peripheral nervous system and for macrophages

Answer 36

resticted blood flow

Answer 37

programmed cell death

Answer 38

loss of myelin sheath

Answer 39

* an obligate intracellular parasite whose primary host is humans * likely that the leprosy bacilli started parasitic evolution in humans or early hominids millions of years ago * makes leprosy the oldest human-specific infection

Answer 40

-intraceullar therefore small genome through reductive evolution -evolved to incresingly parasitic lifestyle resulting in only being able to grow within host cells * It contained around 1,600 pseudogenes with loss of ~50% of the ancestral genes * Pseudogenes are considered as molecular fossils

Answer 41

* Susceptibility to leprosy varies, with protection heritable * Multiple single nucleotide polymorphisms (SNPs) involving many genes have been found to be associated with increased or decreased protection * Region specific prevalences * Example: * Tol-like receptor 1 (TLR1) mutation from isoleucine to serine at AA 602 * Homozygous individuals protected against leprosy * Suggests TLR1 part of pathogenesis mechanism for leprosy * Involved in immune response/signalling in macrophage

Answer 42

at least one of: 1. definitelossofsensationinapale(hypopigmented)or reddish skin patch 2. thickenedorenlargedperipheralnerve,withlossof sensation and/or weakness of the muscles supplied by that nerve 3. microscopicdetectionofbacilliinaslit-skinsmear

Answer 43

* Paucibacillary (PB) : * a case of leprosy with 1 to 5 skin lesions, without demonstrated presence of bacilli in a skin smear. * Multibacillary (MB) : * a case of leprosy with more than five skin lesions; Image from Open University * or with nerve involvement (pure neuritis, or any number of skin lesions and neuritis); * or with the demonstrated presence of bacilli in a slit-skin smear, irrespective of the number of skin lesions.

Answer 44

* In 1981, the World Health Organization (WHO), recommended the use of multidrug therapy comprising of: * dapsone * clofazimine * rifampin * 6 months treatment for PB * 12 months treatment for MB * Early diagnosis and prompt treatment can help to prevent disabilities * WHO provide the multi drug therapy free of cost- donated through an agreement with Novartis

Answer 45

* Problems of resistance emerging to all three drugs * Dapsone has been used since 1945 * most resistance to this drug * Some cases relapse several years after therapy completed * Second line drugs are available if resistance to MDT arises

Answer 46

* A sulfone antibiotic * inhibitor in the folate synthesizing enzyme system * Folic acid is necessary for bacteria and humans alike * Bacteriostatic * Resistance can arise through point mutations on gene (folP1) for target enzyme

Answer 47

* Ansamycin class of antibiotics * Semisynthetic as it is modified from the natural product rifamycin * Action is as an RNA polymerase inhibitor * Blocks bacterial transcription * Side effects common * Resistance occurs through mutations at binding site of rifampicin on RNA pol

Answer 48

* Synthesised for 70 years * Molecular mode of action against mycobacteria unclear! * anti-inflammatory * Resistance can occur through over expression of transporters

Answer 49

* Community awareness is key * Case detection and treatment with MDT * WHO recommends tracing household contacts along with neighbourhood and social contacts of each patient * administration of a single dose of rifampicin as preventive chemotherapy to close contacts * BCG vaccination given primarily for TB may offer some protection against leprosy

Answer 50

* Many people living with leprosy are unable to work due to disability caused by the disease or may face stigma that prevents them from working * In some countries, the law allows a person to legally divorce a spouse because they are affected by the disease * The stigma of leprosy affects the physical, psychological, social, and economic well-being of those with leprosy, contributing to the cycle of poverty in the affected regions

Answer 51

* As a curable disease there is an aim to eradicate it within the human population through interruption of transmission The Global Leprosy Strategy 2021–2030 “Towards zero leprosy” 1. implement integrated, country-owned zero leprosy road maps in all endemic countries 2. scale up leprosy prevention alongside integrated active case detection 3. manage leprosy and its complications and prevent new disability 4. combat stigma and ensure human rights are respected

Answer 52

-infectious air bourne disease -main causal agent is Mtb) -immune response can contain Mtb as latent form of disease -active form is cotagious and causes disease symptoms -primarily a pulmonary disease (lungs) -can cause disease in most parts of body -2021 second leaing infectious cause of death -many low and middle income countries TB is a major cause of morbidity

Answer 53

* Curable with prolonged multidrug treatment regimes * Increasing problems with drug resistance * BCG vaccine offers some protection * Other mycobacteria can also cause tuberculosis from the Mycobacterium tuberculosis complex (MTBC) including M. bovis

Answer 54

sub saharan africa and asia

Answer 55

estimated HIV prevalence in new and relapse TB cases

Answer 56

-primarily airborne disease -not highly infectious (3-10 people) -long period of infectiousness without treatment 1yr<

Answer 57

-eliminated or -latent = strong cell mediated response or -active = weak cell mediated response

Answer 58

* Pulmonary presentation * a bad cough that lasts 3 weeks or longer * pain in the chest * coughing up blood or sputum (phlegm from deep inside the lungs) * Other symptoms of TB disease are: * weakness or fatigue * weight loss * no appetite * chills * fever * sweating at night * TB in other parts of the body symptoms depend on part affected

Answer 59

* Physiology- night sweats, temperature, persistent cough, weight loss, fatigue * Smear test- microscopic visualization of acid-fast bacilli in the sputum * X-ray of the chest to detect patches on the lungs * Cultivation sputum using highly growth sensitive systems such as the MGIT

Answer 60

* Tuberculin skin test (Mantoux test) for hypersensitivity to antigens of Mtb. * IFN-gamma release assay * T-SPOT.TB assay for activated TB-specific effector T cells (TB ELISpot) * Detection of Mtb specific antigens in the blood * Detection of specific genes using qPCR GeneXpert targets Mtb using rpoB, also will detect rifampicin resistance

Answer 61

* MDR-TB is resistant to at least isoniazid and rifampicin, the two most important first-line drugs used in the treatment of TB. * This may result from either primary infection with drug-resistant bacteria or * May develop in the course of a patient’s treatment when non-optimal treatment durations or regimens are used. * Cure rates for MDR-TB are lower, typically ranging from 50% to 70%. * XDR-TB is resistant to isoniazid and rifampicin as well as any

Answer 62

* XDR-TB is resistant to isoniazid and rifampicin as well as any fluoroquinolone and any of the second-line anti-TB injectable drugs (amikacin, kanamycinor capreomycin). * It has very high mortality rates.

Answer 63

* Latent TB is asymptomatic and not infectious; it arises upon immune restriction of the growth of M. tuberculosis in hosts. * Hypoxia (one of several environmental stresses encountered by the Mtb in host cells), has been shown to induce non-replicative bacterial phenotypes, leading to tolerance towards certain drugs like cell-wall inhibitors such as isoniazid * lack of potent drug activity on these bacterial phenotypes may be responsible for prolonging the TB treatment duration

Answer 64

Diagnosis and treatment of active TB cases * Identify and test close contacts * Identifying high risk latent TB cases and giving preventive treatment * Manage environment: * Good ventilation * Natural light (UV kills bacteria) * Good hygiene * Improve conditions- healthy immune system * BCG vaccination

Answer 65

* New drugs * Alter existing drugs * Phage therapy

Answer 66

Each drug candidate is shown with its current clinical phase of development along with the target family. TMC207 is in phase IIb trials for MDR-TB and in phase Iia trials for DS-TB. The structure of AZD-5847 has not been disclosed. NDA, new drug application (for regulatory approval)

Answer 67

-low infectious dose (1 cell) -intracellular pathogens - in macrophage -resistant cell wall -subvert the human immune system (enable macrophage survival) -mycobacteria form characteristic granulomatous lesions - immune cell cluster limiting mycobacterial invasion which mycobacteria can survive within -slow growing

Answer 68

-typically not pathogenic environment -cause disease infrequently - opportunistic pathogen -in immunocomprised and immunocompetent -no person-person transmission -pulmonary disease is most common especially with those who have pre-esisting lung disease -often MISDIAGNOSED as tb

Answer 69

-increased prevalence in north america, europe and asia over the last few decades

Answer 70

spread through body

Answer 71

-cervical lymohadenitis -swimming pool granuloma -buruli ulcer (m. ulcerans)

Answer 72

-prolonged multi-drug therapy for pulmonary NTM (12-24 months) -high rates of re-infection (rather than recurrence) -frequent adverse drug reactions -20-40% of MAC-lung disease patients initially fail to respond -dug resistant -co-morbidity

Answer 73

-indolentnecrotsising disease of the skin, subcutaneus tissue and bone -the third most common mycobacterial disease (least understood) -cutaneous ulcers caused by M. ulcerans were discovered at nearly the same time in two regions of southern hemisphere

Answer 74

causing little or no pain

Answer 75

death of tissues

Answer 76

-painless necrotic skin lesions -mycobacterium ulcerans is closely related phylogenetically to tuberculosis -replication and persistance of M. ulcerans in BU lesions is profoundly influenced by production of mycolactone (other bacteria dont tend to have cytotoxins) -a cytotoxin that has immunosuppressive properties

Answer 77

across africa and australia

Answer 78

-there is little evidence of human to human transmission -infected by envronment or vectors -in endemic regions the disease is highly focal and usually associated with wetlands or coastal regions -PCR testing of environmental samples such as water aquatic plants soil and detritus has found evidence of the bacteria -insects such as mosquitos and water-residing btiing arthropods have been associated with M. ulcerans epidemiologically and via PCR testing therefore proposed as vectors for transmission -possibly native possums

Answer 79

-insect samples were pooled by type -monthly collection -testing in pools of insects by type -some types of insect more positive than others seasonal effect KEY= non-endemic area had no PCR positive insect pools

Answer 80

-key difference between endemic and non -despite their closephysical proximity the non areas were unaffected by human actvity but in endemic the bank of the nyong river had been deforested

Answer 81

-possum excrement from ground found ulcers with same geome in possums as humans -not peer reviewed

Answer 82

-66,000 mosquitos captured and tested -5/1000 were positive for M. ulcerans (PCR) -Key= genome sequencing showed teh m ulcerans in people possum and humans was identical -mouse model showed mosquitos can transmit m ulcerans

Answer 83

-possums ingest m ulcerans from the environment and/or infected by an insect vector -they applify and shed the bacteria into the environment -insect vectors become contaminated with m ulcerans from environment and/or from contact with infected possums -m ulcerans transmitted to humans via insect vector and/or direct contact with contaminated environment -rare cases of direct transmission from possum to human after bite

Answer 84

-resistance to M.ulcerans has been associated with the development of the Th1 type response -granuloma observed during progression to healing -Progression of disease due primarily to mycolactone - an exotoxin

Answer 85

-lower leg lesions -despite the use of appropriate antibiotics oedematous lesions usually ulcerate -often well into antibiotic treatment and require debridement +/2 skin grafting

Answer 86

-low optimal temperatures of growth (29-33°C) that makes the skin its preferntial target -M. ulcerans behaves as an intracellular pathogen triggering inflammatory cell responses and cell mediated immunity -unusual toxin production, mycolactone associated high cytotoxcity that contrasys with the intraceullar traits of its mycobacterial nature -in advanced BU lesions, extraceullar clusters of M ulcerans reside in necotic subcutaneous tissue and are protected from infiltrating leukocytes by the cytotoxic activity of secreted mycolactone -it also has immunosuppressive properties

Answer 87

-precise cellular targets of mycolactone remain mysterious -induces apoptosis of infected cells -inhibits production of the proinflammatory cytokine TNF-alpha by macrophages -suppresses dendritic priming of t cells

Answer 88

-in centre mycolactone is cytotoxic and has burtsts -early immune response may be capacble of clearing an intial M.ulcerans inoculum -spontaneous healing of BU lesions and serological evidence of exposure of healthy individuals to M.ulcerans indicate the host immune system can contain teh infectious pathogen although mechanisms conferring protection are not clear -progression of lesions is highly diverse and not at all non-ulcerative lesions ulcerate -high concentrations og mycolactone in the lesion core cause apoptosis of both resident skin cells and infiltrating leukocytes -chronic necrotic lesions develop with destruction of subcutaneous tissue

Answer 89

-progressuib from the pre-ulcerative to the ulcerative and healing stages of buruli ulcer disease is shown the width of the green, red and yellow shapes denotes the extent of the progression for bacyerial load necrosis and inflammatory responses

Answer 90

-clinical diagnosis -microscopy- smear -culture -PCR-based tests DNA based

Answer 91

-multidrug therapy to reduce selection of drug-resistant strains -combo of rifampicin and clarithomycin in now the WHO recommended treatment -surgery and hospital treatment of wounds for skin grafts -in well developed lesions with ongoing necrosis due to teh effects of high mycolactone toxin load then the removal of this tissue is necessary -physiotherpay and rehabilitation

Answer 92

-vital but often goes neglected -healing time can be months or years to heal even after antibiotic treatment -improved wound dressings emerging from other ulcer disease eg diabetes

Answer 93

-active surveillance -case management -treatment -case study is republic of congo -identification of this zone as a high risk area for buruli ulcer disease helped the ministry early detection, biological confirmation and treatment programs

Answer 94

-some protection seen with BCG but inconsistent -vaccines specific to m ulcerans targeting a mycolyl transferase of the bacteria being tested

Answer 95

-swimming -fishing -agricultural works -mosquito nets may help if insect borne (australia) -good pre-existing wound care -protective clothing to prevent wounds

Answer 96

-Research priorities recommended in the US and the UK include rapid diagnostic tools fast identification of infecting species -methods (ELISA, LAMP and mycolactone specific tests) -simple and cheap screening tool to identify patients -faster initiation of appropriate treatment and ultimately superior care

Answer 97

-efforts to shorten the duration of treatment are in progress involving two studies -Telacebec is a new anti-tuburculsis drug developed by korean company quirent -clinical trial comparing the standard treatment of the combination of rifampicin and clarithromycin for 8 weeks and amoxicillin/clavulanate for 4 weeks

Answer 98

-the study of fungi (including yeats,moulds and fleshy fungi)

Answer 99

-eukaryotic -rigid cell wall consisting of layers of polysaccahrides which forms a rigid matrix -chemoheterotrophs (require organic compounds for both carbon and energy sources) -obtains nutrients as saprophytes (live off decaying matter) or as parasites (living matter) -can stimulate plant roots to proliferate -lichens are composed of fungi and a photosynthetci component either a eukaryotic alga or a cyanobacterium -disease causing fungi mostly infects skin, hair and nails can hydrolyse keratin

Answer 100

-produce a toxic compounds called aflatoxin which causes liver cancer

Answer 101

-hallucinogenic drug LSD produced by fungi

Answer 102

-pathogenic for animals -play a major role in the recycling of nutrients by their ability to cause decay and are used by industry -however they also lead to undesireable economic effects such as destrucyion of fruits, grains wood and leather products

Answer 103

Eukaryotes encompass the other five Kingdoms: Protista (now often called Protozoa), Chromista, Plantae, Animalia and Eumycota.

Answer 104

-since fungi have several distinguishing features eukaryotic, heterotrophic (cant make own food) and osmotrophic (absorb food) they develop a rather diffuse branched and tubular body (radiating hyphae making up mycelia or colonies and reproduce by means of spores

Answer 105

i) by causing immune responses that result in allergic (hypersensitivity) reactions following exposure to specific fungal antigens ii) by producing toxins a large diverse group of fungal exotoxins produces aflatoxins which induce tumours in birds iii) by infection the growth of a fungus on or in the body is MYCOSIS

Answer 106

-a few fungi have evolved a rather specific ability to attack the outer surface of human beings

Answer 107

-A few other fungi which cause disease in people are normally soil organisms, -but have also adapted to life in the unusual and rather hostile environment of the human body, often responding to this environment by developing a different morphology

Answer 108

-fungi that can attack us when defences are down -when our immune systems themselves are diseased or deficient or when we artificially suppress them

Answer 109

(superficial mycoses) involved the outer layers of the skin and cause an allergic orinflammatory responses

Answer 110

usually involving fungi of low inherent virulence which have been introduced to the tissues through a wound of some kind and which remain localized or spread only by direct mycelial growth

Answer 111

-caused by true pathogenic fungi or by opportunistic saprobic fungi -could not infect a healthy host but can attack individuals whose immune system is not working or is comprimised -may become widley disseminated in host

Answer 112

bloodstream

Answer 113

= the medical name for a group of related skin infections, including athlete's foot, jock itch, & ringworm

Answer 114

-inhalation of spores leads to fungi in bloodstream can lead to brain damage

Answer 115

histoplasmosis

Answer 116

[These also include superficial cosmetic fungal infections of the skin or hair shaft where no living tissue is invaded and there is no cellular response from the host. Essentially no pathological changes are elicited

Answer 117

utilise keratin as a nutrient source: they invade keratin via enzymatic digestion and mechanical pressure

Answer 118

-caused by T. rubrum. Sub-clinical infection causes mild maceration of toe -usually caused by the shedding of skin scales containing viable infectious hyphal elements [arthroconidia] of the fungus.

Answer 119

-topical therapy (creams) but oral antifungals are used for extensive skin infections or those for nail and scalp -prophylactic use of antifungal foot powder elps reduce spread of infection for swimmers

Answer 120

-widely used bis-triazole antifungal agent -as with other triazoles it has a membered ring structures containing three nitrogen atoms

Answer 121

-by inhibition of cytochrome P450 14a-demethylase an enzyme in teh sterol biosynthesis pathway that leads from lanosterol to ergosterol an essential component of the fungal cytoplasmic membrane

Answer 122

-unicellular fungi which usually appear as oval cells -typical eukaryotic structures -facultative anaerobes get their energy through aerobic respiration as well as fermentation

Answer 123

-The body does this by recognizing molecules unique to micro-organisms that are not associated with human cells -These unique molecules are called pathogen-associated molecular patterns. -Components of the yeast cell wall bind to pattern- recognition receptors on a variety of defense cells of the body and triggers innate immune defenses such as inflammation, fever, and phagocytosis. -Yeast cell wall components also activate the alternative complement pathway and the lectin pathway, defense pathways that play a variety of roles in body defense.

Answer 124

-in addition to its usual oval budding form, is also able to produce pseudohyphae. -Buds elongate forming a tube-like structure called a germ tube. The elongated buds remain attached to one another and eventually produce a filament called a pseudohypha because it resembles the hypha (a long filament of cells) of a mould. -The pseudohyphae help the yeast to invade deeper tissues after it colonizes the epithelium. Since Candida is able to grow as a yeast as well as in a pseudohyphal form it is said to be dimorphic i.e. it has two growth forms yeast-like and mould-like.

Answer 125

Branching filaments of attached, elongated yeast cells resembling the hyphae of moulds

Answer 126

asexual reproductive spores

Answer 127

thick- walled survival spores

Answer 128

found as normal flora on the mucous membranes and in the gastrointestinal tract; usually held in check by: 1) normal flora bacteria; and 2) normal body defenses. Candida can cause a variety of opportunistic infections in people who are debilitated, immunosuppressed, or have received prolonged antibacterial therapy. Women who are diabetic, pregnant, taking oral contraceptives, or having menopause are also more prone to vaginitis.

Answer 129

Yeasts reproduce asexually by a process called budding -Yeasts reproduce asexually by a process called budding allowing for genetic recomibination

Answer 130

These conditions alter the sugar concentration and pH of the vagina making it more favourable for the growth of Candida. People who are immunosuppressed frequently develop thrush, vaginitis, and sometimes disseminated infections.

Answer 131

candidiasis Candida most commonly causes vaginitis (inflammation of the mucous membranes of the vagina), thrush (infection of the mucous membranes of the mouth), balantitis (Candida lesions on the penis from a female with vaginitis), and cutaneous infections (Infections of moist skin or the nail beds) Less commonly, Candida can infect the lungs, blood, heart, and meninges

Answer 132

Clinically, white plaques that resemble milk curd form on the buccal mucosa and less commonly on the tongue, gums, the palate or the pharynx. Symptoms may be absent or include burning or dryness of the mouth, loss of taste, and pain on swallowing.

Answer 133

can occur between the fingers or toes, or in the groin "Nappy rash" candidiasis is common in infants under unhygienic conditions of chronic moisture and local skin maceration associated with irritation due to irregularly changed unclean nappies

Answer 134

 a common condition in women often associated with the use of broad-spectrum antibiotics, the third trimester of pregnancy, low vaginal pH and diabetes mellitus Sexual activity and oral contraception may also be contributing factors and infections may extend to include the vulva and the cervix. Symptoms include intense itching, burning or soreness and production of a creamy white, curd-like discharge. Chronic refractory vaginal candidiasis, associated with oral candidiasis, may also be a presentation of HIV infection or AIDS

Answer 135

a primary or secondary mycotic infection caused by members of the genus Candida clinical manifestations may be acute, subacute or chronic to episodic. Involvement may be localized to the mouth, throat, skin, scalp, vagina, fingers, nails, bronchi, lungs, or the gastrointestinal tract, or become systemic as in septicaemia and meningitis. In healthy individuals, Candida infections are usually due to impaired epithelial barrier functions and occur in all age groups, but are most common in the newborn and the elderly. They usually remain superficial and respond readily to treatment. Systemic candidiasis is usually seen in patients with cell-mediated immune deficiency, and those receiving aggressive cancer treatment, immunosuppression, or transplantation therapy.

Answer 136

1)collect samples from skin 2)direct microscopy =Examine specimens for the presence of small, round to oval, thin-walled clusters of budding yeast cells (blastoconidia) and branching pseudohyphae

Answer 137

-a chronic localised disease of the skin and subcutaneous tissues causative organisms are Cladophialophora sp. Fonsecaea sp., Phialophora sp. -infections are caused by the tramuatic implantation of fungal elements into the skin and are chronic slowly progressive and localised -characterised by crusted, warty lesions usually involving the limbs world-wide distribution but more common in bare footed populations living in tropical regions

Answer 138

-presence in skin scrapings and/or biopsy tissue of brown pigmented, planate-dividing, rounded sclerotic bodies from a patient with supporting clinical symptoms

Answer 139

-can involve surgical removal of tissue (through requires removal of a margin of uninfected tissue to prevent local dissmination -flurocytosine (a pyrimidine analog) and the azoles thiabendazole and itraconazole

Answer 140

Primarily a chronic mycotic infection of the cutaneous or subcutaneous tissues and adjacent lymphatics Characterized by nodular lesions which may ulcerate. Infections are caused by the traumatic implantation of the fungus into the skin, or very rarely, by inhalation into the lungs. Secondary spread to joints, bone and muscle is not infrequent, and the infection may also occasionally involve the central nervous system, lungs or genitourinary tract.

Answer 141

is rare; usually caused by the inhalation of conidia. Symptoms are non-specific and include cough, sputum production, fever, weight loss and upper-lobe lesion. Haemoptysis (coughing up blood) may occur and it can be massive and fatal. The natural course of the lung lesion is gradual progression to death.

Answer 142

-Tissue biopsy will contain very low numbers of narrow base budding yeast cells (2-5um)

Answer 143

Cutaneous lesions respond well to saturated potassium iodide itraconazole & terbinafine have also proved to be effective

Answer 144

an allylamine - a synthetic antifungal agent it is highly lipophilic in nature and tends to accumulate in skin, nails, and fatty tissues

Answer 145

As with the other allylamines, terbinafine inhibits ergosterol biosynthesis via inhibition of squalene epoxidase. This enzyme is part of the fungal sterol synthesis pathway that creates the sterols needed for the fungal cell membrane

Answer 146

-although pneumocytis carinii based on its appearence and sensitivity to antiprotozoan drugs thought to be protozoan it is more closely related to fungi -thought to be transmitted from person to person by the respiratory route and is almost always asymptomatic. -However, in persons with highly depressed immune responses, P. carinii can cause an often lethal pneumonia called PCP (Pneumocystis carinii pneumonia).

Answer 147

-Disease caused by the dimorphic fungus Blastomyces dermatitidis (dimorphic = having two distinct forms, as in some fungal pathogens of humans, which are yeast-like in the host, but mycelial in culture) -Endemic in the southeastern and south central states of North America -associated with occupational or recreational activities around streams or rivers with high content of moist soil enriched with organic debris and/or rotting wood. -Infection is acquired via inhalation of the conidia, which transform into the yeast form once in the lungs. After 30 to 45 days an acute pulmonary disease indistinguishable from a bacterial pneumonia may occur. However, at least 50% of primary infections are asymptomatic.

Answer 148

-Condition caused by infection with the dimorphic endemic fungus Histoplasma capsulatum -most common cause of fungal respiratory infections in the world -majority of acute cases of infection with this fungus follow a sub-clinical and benign course in normal hosts -However, a disseminated and potentially fatal picture is seen among immunosuppressed individuals, children <2 years old, the elderly and people exposed to a very large inoculum.

Answer 149

-skin lesion and can become disseminated to internal organs

Answer 150

-absorbs nutrients from dead organic matter and produces infectious spores -when inhaled they encounter the warm moist envrionment of the lungs and undergo a transformation to the yeast or parasitic form

Answer 151

-refers to the broad range of disease states whose etiological agents are members of the genus Aspergillus -Aspergillus spp. are ubiquitous organsims progressievly associated witha growing spectrum of infections in immunocomprimised hosts -aspergillus fumigatus is responsible for over 90% of cases of invasive asperigillosis

Answer 152

-produces an allergy to the spores of aspergillus molds -common in asthmatics (up to 20% of asthamtics may develop this at some point) -also common in CF patients as they reach adolescence and adulthood -symptoms are similar to those of asthma: intermittent episodes of feeling unwell, coughing and wheezing some pateints cough up brown coloured plugs of mucus diagosis: X rays

Answer 153

-disease where aspergillus grows within a cavity of the lung (previously damaged by disease like TB) -any disease that causes cavities in lung can lead to an individual developing an aspergilloma -the spores penetrate the cavity and germinate forming a fungal ball within the cavity -illness is caused by secretion of toxins/other products

Answer 154

-brain fog (STM lost) -weight changes -chronic cough -feeling rundown -coughing of blood (hemotypsis can occur in up to 50-80% of affected people -diagnosis is made by x rays scans of lungs and blood tests

Answer 155

-often fatal \-no good diagnostic test -often treatment must be started when suspected infection has occured -RISK-as bone marrow transplant, low white cells after cancer treatment, AIDS or major burns.->chronic granulomatous disease which puts affected people at moderate risk -people with invasive aspergillosis usually have a fever and symptooms from the lungs (cough chest pain or discomfort which do not respond to standard antibiotics x rays and scans are usually abnormal and help to localize the disease -bronchoscopy (inspection of the inside of the lung with a small tube inserted via the nose) is often used to help to confirm the diagnosis

Answer 156

-effective chemo against systemic fungal infections is very difficult -one of the most effective antibiotics is amphotericin B (punches holes in membranes) a polyene -side effects on kidney toxicity -exposure to fungi can rarely be eliminated except using air filtration in restricted local environments

Answer 157

inhibit biosynthesis of membranes

Answer 158

-6-7 million infected in latin america (endemic) -incidence of diseases 500000 new cases per year 10000 deaths per year -high mortality sometimes without knowledge of infection -highest burden of disability-adjusted life years (DALYs) lost amoung the NTDs

Answer 159

-41% of 283 andean mummies dated 9,000 yrs old positive for T. cruzi DNa -40% of mummies have t crucei -humans are a very recent host -T cruzi is > 150 million years old

Answer 160

-brazillian doctor first described the disease and life cycle

Answer 161

-reduviid or triatominae bugs -not effcient at transmitting parasite -able to surive for months without bloodmeal therefore control is more difficul -8-10 times more bloodmeal than bodyweight therefore large number of parasites 5 stages until develop wings one bloodmeal is required for each stage

Answer 162

Vector-borne by “kissing bugs” (80%) * Transfusion of infected blood (<4% -20%) * Congenital: mother to foetus (regionally high) COMMON FORM OF TRANSMISSION * Accidental ingestion of infected sources

Answer 163

-8 million people are infected -10,000 deaths per year -remains one of the biggest public health problems in 21 latin countries -urbanisation migration increased transmission

Answer 164

-Chagas is long-lived infection with asymptomatic chronic carriers. -leads to unusual global distribution (lots of cases in europe dependent on arrangements made with south american countries -subsequent (autochthonous) transmission is NOT vector-borne rather mainy congenital also blood transfusions and infected organ transplants

Answer 165

-poverty/house construction -favourable triatomine bug habitats in poorly constructed houses -deforestation and human colonization of triatomine habitats -provides abundant/stationary blood sources -rural to urban migration -blood transfusions congenital transmission

Answer 166

-Acute (symptomatic) form (4-8 weeks) – most often seen in children -ever, swelling lymph glands, liver and spleen enlargement, local injammation of inoculation site e.g. “Romaña’s sign” (photo). Abundant parasites in the bloodstream -fatality rate 0.25-0.5% -myocarditis meningoencephalitis both life threatening

Answer 167

-cardiomyopathy in 20-30% of chronically infected individuals -develop digestive damage (megaviscera -peripheral nervous involvement

Answer 168

-chronic without successful treatment is life long -indeterminate forms of infection = no symptoms -20-30% of people who initially have the inteterminate form progress to clinical conditions developed over three decades -cardiac disease (more common) and plethora of complications leading to sudden death -gastrointestinal diseases (less common) of the oespohagus/ colon with advancement to megaesophagus/megacolon predominant in southern cone -social consequences of infection too

Answer 169

-high parasitaemia -microscopy of stained blood smear PCR

Answer 170

-amastigotes remian in cardiac/skeletal muscle/ macrophages -scarce trypomatigotes in blood -two serological IgG antibody tests due to low sensitivity -no satisfactory test to define parasitological cure (low PCR sensitivity) -hit or miss success

Answer 171

drugs = Nifurtimox, Benznidazole -effective against acute and chronic -serious/frequent side-effects (40%) more common with increasing age -in acute treatment reduces and shortens clinical severity and duration of detectable parasitemia -60-85% cure in acute phase

Answer 172

recommends treatment for acute, congenital, and reactivated T. cruzi infection, and for children (up to 18 years of age) with chronic infection.

Answer 173

-No drugs effective for chronic phase -debate over usefulness in adults with long standing infection

Answer 174

-serious side effects -access: less than 1% of patients have access ro benznidazole -only recomeded in areas with vector control -due to re-infection and risks associated with treatment -disease is poorly understood by health professionals in non-endemic areas - making detection in acute phase difficult -desperately need new drugs and to improve parasitological detection

Answer 175

-screen blood transfusions and organ donation -screen pregenat women and children to control congenital transmission -promote health seeking behaviour and awareness amoungst health professionals

Answer 176

-no vaccine -sustained vector control of intra-domicillary vectors in latin america -prevent vector borne transmission -promote engagement with vector control activities

Answer 177

-no vaccine -chemo cannot be relied on to prevent spread of infection only useful in acute/early chronic -not widely available -vector infestation leads to high levels of re-infection -need to focus on prevention

Answer 178

- controlling intra-domiciliary vectors in Latin America - screening bloodbanks for transfusions - screening organs for transplantation - screening for congenital infection

Answer 179

-Through Na channels impacts CNS contact insecticides - vector has to land on insecticide

Answer 180

-insecticide impregnated nets (ITNs) -house improvements (environmental management) Plastering of walls (earth, cow dung, lime or cement mixes) to seal gaps -social interventions -school teachers meetings and house vists -sustainability is a key parameter -good practises may be required but abandoned if regarded low priority

Answer 181

-focused on reducing vector density -launched in 1991 -serological screening of blood -housing improvements

Answer 182

-highly domesticated vector -Genome has reduced in size therefore less adaptable -not huge fluctuations in climate in south america

Answer 183

populations have gene flow between them therefire can infect on seasonal basis

Answer 184

was young so hard to detect

Answer 185

Argentina, Bolivia, Paraguay * 1.3 million km2 * Indigenous communities * Highest transmission * House infestation 82–100% * T. infestans infection with T.cruzi, 50% MARGINALISED COMMINITY therefore dont have voice

Answer 186

-poor recapture success

Answer 187

Household infesta/on threshold to trigger vector control by IRS IRS “aaack phase” conducted typically un?l reduced to <5% of houses infested; Infesta?on indicated by Timed Manual Capture (TMC): 0.5 person hours search for vectors in household buildings

Answer 188

Treatment of childhood infec?on recommended only if area is under ecec?ve vector control commonly dedned as: House infesta?on Index: <3% houses* in community infested, and absence of infestation in case households

Answer 189

reduce crevices and increase surface adhesion of IRS insecticides

Answer 190

-house improvement + IRS -Assisted IRs

Answer 191

-higher T. infestans genetic diversity in blivian andes suggests * Region of origin and geographic dispersal * Andean and non-Andean T. infestans populations are essentially digerent * Still limited gene how between sylvatic and domestic populations

Answer 192

-Rhodnius prolixus -Triatoma dimidiata

Answer 193

* Organophosphates (Dieldrin); Organochlorines (benzene hexachloride (BHC)); Carbamates (propoxur) * Synthe?c pyrethroids (cypermethrin, cyWuthrin, deltamethrin, permethrin, lambdacyhalothrin)

Answer 194

Latin America * Incidence declined from 700,000 to 40,000 cases per year in 25 years * Mortality decline: 45,000 to 12,500 deaths * But still annual cost of US$8 billion * Elimination of T.infestans in majority of region

Answer 195

1) Elimina?on as a public health problem (in 20 endemic countries + 75% access to treatment); 2) Interrup?on of intradomiciliary (vectorial) transmission (0% Infesta?on Index and 0% T. cruzi human infec?on incidence; 3) Elimina?on of blood transfusion & ?ssue transplant transmission (100% of target countries); 4) Interrup?on of congenital transmission: 90% screening coverage and treatment of women, and when infected, screening of their new-borns and siblings.