Leishmania donovani Leishmania infantum Leishmania chagasi

Medically Important Parasites (2) Flashcards by Josephine Gue

3 forms of leishmaniasis

Cutaneous leishmaniasis
Kala Azar (Dum dum fever)
Mucocutaneous leishmaniasis

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Cutaneous leishmaniasis species

Leishmania tropica
Leishmania aethiopica
Leishmania major

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Cutaneous leishmaniasis vector

Sandfly (Phlebotomus spp.)

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Cutaneous leishmaniasis disease characteristics

Dry, raised, ulcerated lesions at bite sites

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Kala Azar species

Leishmania donovani
Leishmania infantum
Leishmania chagasi

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Kala Azar disease progression

L. donovani parasitise reticuloendothelial cells

* Infected macrophages disseminate throughout the body - to lymphoid tissue (spleen, liver, bone marrow)

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Kala Azar vector

Sandfly (Phlebotomus spp.)

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Kala Azar reservoir host

Dogs
Rodents
Porcupines
Cats

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Mucocutaneous leishmaniasis species

Leishmania braziliensis
Leishmania panemensis
Leishmania peruviana
Leishmania guyanensis

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Mucocutaneous leishmaniasis reservoir host

Rainforest rodents

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Mucocutaneous leishmaniasis disease characteristics

Development of ulcer on or about oral and nasal mucosa

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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

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Blood protozoa

Trypanosoma brucei, gambiense, rhodesiense

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Trypanosoma vector

Tsetse fly

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Trypanosoma reservoir host

Ungulates (wild animals such as deers)

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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

1. Oocysts shed in cat feces 2. Oocysts transform into tachyzoites shortly after ingestion by rodents 3. Tachyzoites localise in neural and muscle tissue and develop into tissue cyst bradyzoites. 4. 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