14. Protozoans: Leishmaniasis Flashcards
learn some worms yeh
what are the three main types of leishmaniasis
- visceral leishmaniasis
- cutaneous leishmaniasis
- mucocutaneous leishmaniasis
what is mucocutaneous leishmaniasis
disfiguring infection of the soft palate of the face
how is leishmaniasis transmitted
bites of females sand flies
name a species of sand fly that transmits leishmaniasis
phlebotomus
briefly describe the life cycle of leishmaniasis
sandfly ejects the infected stage during blood meal
promastigotes are phagocytosed by macrophages
promastigotes transform into amastigotes before multiplying
sandfly takes next blood meal and consumes infected macrophages
which type of leishmaniasis is fatal if left untreated
visceral (95% case fatality)
what are some reservoirs for leishmaniasis
dogs & rodents
what are some measures taken to control leishmaniasis reservoirs
ministry of health in Brazil order the culling of approx 1 million dogs per year
what is the clinical diagnosis for VL
1 month - 10 years
describe the onset of VL
fever, splenomegaly, anaemia
VL can develop into post kala-azar dermal leishmaniasis, what is this?
skin rash with parasite rich nodules
what is the gold standard diagnostic test for VL
culturing promastigotes from splenic or bone marrow samples
describe the KAtex urine test
uses latex particles coated with antibodies against the leishmania antigen which is found in the urine
HIGH SPECIFICITY
describe the direct agglutination test
detects antigens to the parasite In the blood or serum of the patient
what is a negative result for the direct aggulitantion test (DAT)
dark blue = negative
what is a positive result for the direct aggulitantion test (DAT)
pale blue = positive
name a strength and limitation of DAT (direct agglutination test)
strength = easy to read, does not require specialist information
limitation: reproducibility problems (due to thermal instability of antigen)
what does IFAT stand for
indirect fluorescent antibody test
what does ELISA stand for
enzyme-linked immunosorbent assay
how does ELISA work
well plates coated with antigen of interest, host serum containing antibodies are applied to the wells and BINDING is measured used an enzyme labelled secondary antibody
what test can be used to diagnose L. Donovan and L. infantum
Immunochromatographic strip test
how does immunochromatographic strip tests work, what’s the key issue with them?
ICT = rapid nitrocellulose test with specialised antigens that detect l. Donovan and l. infantum antibodies
issue: produces lots of false positives
why is PCR based tests not appropriate for leishmaniasis
requires specialist equipment that is not field friendly
mainly used in specialist centres which many endemic countries lack
what is the transmission cycle of VL in brazil
- sandfly feeds infected dog
- parasite cycles between sandfly’s and dogs - sylvatic cycle
- sandfly takes blood meal on human
= infection
how can an electronic nose be used to detect the conductivity
analysis of infected and uninfected dog hair and blood
- nose was able to detect clear different between infected and uninfected dogs
- high se and sp > 94%
what is the reason why infected dogs have different odours to uninfected dogs
to make the infected individual more attractive to sandflies
= more blood meals = more transmission
What is a sylvatic cycle
Virus cycles between animal and sandfly, does not yet feed on a human
