Pathogenesis of Parasitic Infections Flashcards
What are the two main types of leishmaniasis?
β Visceral and Cutaneous
What are the three geographical regions affected by visceral leishmaniasis?
β Asia
β Middle east/africa/asia
β Latin america
What type of visceral leishmaniasis affects Asia?
β Leishmania donovani
What type of visceral leishmaniasis affects the Middle east & Africa?
β L.Infantum variants
What type of visceral leishmaniasis affects Latin America?
β L. Chagasi
What types of cutaneous leishmaniasis affect the new world?
β L.braziliensis/amazonensis/mexicana
What is Leishmaniasis caused by?
β Sand fly
Describe the lifecycle of leishmaniasis?
β The sandfly bites and transmits a promastigote
β The promastigote invades immune cells like macrophages
β Inside the macrophage it forms nests of amastigotes
β the cells eventually burst which release lots of amastigotes and infect other cells which can be taken up by the fly
What is the vector of leishmaniasis?
β Lutzomyia/phlebotomus
In what regions are sandflies common and who do they affect?
β Tropical regions
β people who live in housing of poor standard such as adobe
What type of an infection is leishmaniasis?
β Zoonotic
What is the sylvatic and domestic reservoir of leishmaniasis?
β sylvatic β rodents
β domestic β dogs
Describe the progression of cutaneous leishmaniasis after a bite?
β There is a papule that forms and spreads
β the center becomes necrotic and ulcers form
What happens if you get infected as a child with cutaneous leishmaniasis?
β early immunity to that form of leishmania
When does diffuse cutaneous leishmaniasis occur?
β When there is lack of an immune response to the leishmania
Describe the progression of mucocutaneous leishmaniasis?
β a small proportion of individuals get congested noses
β lesions occur in the mucus membranes
β lesions occur and destroy the nasal septum
When do people get infected with mucocutaneous leishmaniasis?
β as children
What are the three phases of cutaneous leishmaniasis?
β Acute lesions
β Latency
β Relapse (rare)
Describe the pathogenesis of acute lesions in cutaneous leishmaniasis?
β Tissue damage is caused by inflammatory response to the presence of parasites in macrophages
β parasite killing by Th1 proinflammatory responses and macrophage killing
Describe the pathogenesis of the latency phase in cutaneous leishmaniasis?
β regulatory immune response characterised by balance of Th1 and anti-inflammatory responses
β parasites remain present long term
What is a recidivans?
β A recurrence of lesions at the old ulcer site
What is mucocutaneous disease associated with?
β strong but inadequate inflammatory response to parasites that have metastasised to mucosa
What can trigger relapse in leishmaniasis?
β alteration in immune response
What are the three main species of schistosomiasis and what areas of the body do they affect?
β Schistosoma mansoni - hepatic and intestinal
β S. haematobium - urinary system
β S. Japonicum - hepatic