Medically Important Parasites (2) Flashcards
3 forms of leishmaniasis
- Cutaneous leishmaniasis
- Kala Azar (Dum dum fever)
- Mucocutaneous leishmaniasis
Cutaneous leishmaniasis species
- Leishmania tropica
- Leishmania aethiopica
- Leishmania major
Cutaneous leishmaniasis vector
Sandfly (Phlebotomus spp.)
Cutaneous leishmaniasis disease characteristics
Dry, raised, ulcerated lesions at bite sites
Kala Azar species
- Leishmania donovani
- Leishmania infantum
- Leishmania chagasi
Kala Azar disease progression
- L. donovani parasitise reticuloendothelial cells
* Infected macrophages disseminate throughout the body - to lymphoid tissue (spleen, liver, bone marrow)
Kala Azar vector
Sandfly (Phlebotomus spp.)
Kala Azar reservoir host
- Dogs
- Rodents
- Porcupines
- Cats
Mucocutaneous leishmaniasis species
- Leishmania braziliensis
- Leishmania panemensis
- Leishmania peruviana
- Leishmania guyanensis
Mucocutaneous leishmaniasis reservoir host
Rainforest rodents
Mucocutaneous leishmaniasis disease characteristics
Development of ulcer on or about oral and nasal mucosa
Leishmania donovani life cycle
- Sandfly takes a blood meal (injects prom astigmatism stage into skin)
- Promastigotes are phagocytised by macrophages
- Promastigotes transform into amastigoted inside macrophages
- Amastigotes multiply inside cells of various tissues
- Sandfly takes a blood meal (ingests macrophages infected with Amastigotes)
- Amastigotes transform into promastigote stage in midgut
- Divide in midgut and migrate to proboscis
Blood protozoa
Trypanosoma brucei, gambiense, rhodesiense
Trypanosoma vector
Tsetse fly
Trypanosoma reservoir host
Ungulates (wild animals such as deers)
Trypanosoma pathology
• Infection has chronic cause, end with CNS involvement and death
Trypanosoma disease
Cause sleeping sickness
Trypanosoma gambiense/rhodesiense life cycle
- Tsetse fly takes a blood meal (injects metacyclic trypomastigotes)
- Injected metacyclic trypomastigotes transform into bloodstream trypomastigotes, which are carried to other sites
- Trypomastigotes multiply by binary fission in various body fluids eg. Blood, lymph, spinal fluid
- Trypomastigotes in blood
- Tsetse fly takes a blood meal (bloodstream trypomastigotes are ingested)
- Bloodstream trypomastigotes transform into procyclic trypomastigotes in tsetse fly midgut. Procyclic trypomastigotes multiply by binary fission
- Procyclic trypomastigotes leave midgut and transform into epimastigotes
- Epimastigotes multiply in salivary gland. They transform into metacyclic trypomastigotes
Tissue protozoa
Trypanosoma cruzi
Trypanosoma cruzi vector
Reduvid bug, kissing bug, triatomid bug (2 species: triatoma, Rhodnius or Parastrongylus)
Trypanosoma cruzi transmission
- kissing bug
- blood transfusion
- Organ transplantation
- Transplacentally
- Lab accidents
Trypanosoma cruzi clinical symptoms
- Fever
- Chills
- Malaise
- Myalgia
- Fatigue
- Myocarditis
- Damage to CNS -> death
Trypanosoma cruzi zoonosis
- Dogs
- Rats
- Opossums
Trypanosoma cruzi life cycle
- Triatomine bug takes blood meal (passes metacyclic trypomastigotes in feces, trypomastigotes enter bite wound or mucous membranes)
- Metacyclic trypomastigotes penetrate various cells at wound site, transform into amastigotes
- Amastigotes multiply by binary fission in cells of infected tissues
- Intracellular amastigotes transform into trypomastigotes, the burst out of cell and enter bloodstream
- Triatomine bug takes a blood meal (trypomastigotes ingested)
- Epimastigotes in midgut
- Multiply in midgut
- Metacyclic trypomastigotes in hindgut
Malaria 5 species
- Plasmodium vivax
- Plasmodium malariae
- P. ovale
- P. falciparum
- P. knowlesi
Malaria vector
Female Anopheles mosquito
Malaria asexual and sexual development
- Schizogony (human host)
* Sporogony (mosquito)
Malaria exoerythrocytic cycle
Within liver cells (5 to 16 days)
Malaria erythrocytic cycle
Thousands of merozoites rupture and invade RBCs
Malaria schizogony (humans)
Trophozoite -> continues to enlarge until nucleus divides -> schizont -> forms multiple merozoites -> RBC ruptures -> release merozoites and waste products -> reinfection of new RBC
Malaria gametogony (humans)
Merozoites -> gametocytogenesis-> microgametes (male), macrogametes (female)
Malaria sporogony (mosquito)
Gametocytes -> zygote -> ookinete -> gut wall -> oocyst -> sporocyst -> sporozoites
Toxoplasma gondii main reservoir
Cats
Toxoplasma gondii intermediate host
Cattle, sheep, pig, rodents
Toxoplasma gondii characteristics
- Tissue protozoa
- Oocyst containing 2 sporocysts (4 sporozoites) passed in faeces
- Human infection accidental
Toxoplasma gondii life cycle
- Oocysts shed in cat feces
- Oocysts transform into tachyzoites shortly after ingestion by rodents
- Tachyzoites localise in neural and muscle tissue and develop into tissue cyst bradyzoites.
- Cats become infected after consuming intermediate hosts
Toxoplasma gondii human infection
- Eating undercooked meat of animals harbouring tissue cysts
* Transplacentally from Mother to foetus
Toxoplasma gondii diagnosis
- Serology
- Observing tissue cysts in stained biopsy specimens
- Congenital infections: detecting T. gondii DNA in amniotic fluid using PCR
