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54 Cards in this Set
- Front
- Back
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What type of organism causes Leishmaniasis? Is Leishmania intra- or extracellular?
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It is a protozoan parasite that invades macrophages
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What vector transmits Leishmania?
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Sandfly
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What are the two main reservoirs of Leishmania?
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Rodents and canines
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What is the life cycle stage of Leishmania in humans?
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amastigote
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What are the 3 clinical syndromes of Leishmaniasis?
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Cutaneous, mucocutaneous, and visceral.
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What is cutaneous Leishmaniasis?
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A localized painless lesion, the majority of which are self-healing. The infection is localized to the skin.
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What is mucocutaneous Leishmaniasis? What causes it?
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Infection by L. braziliensis spreads from the skin to mucous membranes and causes destructive lesions.
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What is the classic pentad of symptoms of Visceral Leishmaniasis?
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fever, cachexia, splenomegaly, pancytopenia, hypergammaglobulinemia
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What is Leishmaniasis in the immunocompromised?
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It is an opportunistic infection that is recurrent and cannot be eliminated from the body by anti-parasitics.
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What is required for definitive diagnosis of Leishmaniasis?
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Tissue sample from a scraping, biopsy, or aspirate.
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What is the firstline treatment for all forms of Leishmaniasis?
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Anitmony-based drugs (antimonials)
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What is a characteristic of sandflies that enables a good way to avoid infection with Leishmania?
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They are totally crappy fliers. They can't go very far from animal reservoirs.
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What animal carries Schistosoma?
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snails in freshwater.
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What are the two primary clinical syndromes of Schistosomiasis?
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intestine/liver and urinary.
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What type of parasite is Schistosoma?
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worm
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Where does Schistosoma reside in the human body?
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Venules of the organ it infests
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What actually causes symptomatic disease in Schistosomiasis?
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The eggs.
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What part of the Schistosoma life cycle do humans excrete?
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eggs
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What is the progression of infection by Schistosoma?
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Worm penetrates the skin and travels to the lung and portal vein. They mate and settle in the venules of either the liver or bladder. Eggs are excreted in feces or urine, and any eggs that are not excreted lodge in the venules and cause granulomas and scarring.
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What is acute Schistosomiasis called?
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Katayama Fever
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What are the classic symptoms of Katayama fever?
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fever, urticarial rash, hepatosplenomegaly, and bronchospasms
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How do Schistosoma adults evade the immune system?
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It coats itself in human antigens
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How does Schistosomiasis cause chronic blood loss and inflammation?
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The adult worms live 5 years and continually shed eggs that are immunogenic, and also clog blood vessels causing hemorrhage.
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How can Schistosomiasis cause hydronephrosis?
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Granulomas can coalesce to block urinary outflow from the bladder.
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What species of Schistosoma is mainly associated with liver/intestinal disease? Which species for urinary disease?
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S. masoni for liver/intestinal disease. S. haematobium for urinary disease.
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What is the treatment for Schistosomiasis?
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Praziquantel is excellent.
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What is the vector and primary host of Toxoplasma?
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cats
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What are the 4 means of contracting toxoplasmosis?
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Ingestion of infectious oocysts
Ingestion of tissue cysts from infected animal meat. Vertical transmission from mother to child. Blood transfusion or organ transplant. |
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What is responsible for the majority of toxoplasmosis cases in the world, including the US?
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ingestion of undercooked meats.
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What is the most common site of toxoplasma reactivation in HIV patients?
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CNS
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What is the classic triad of congenital toxoplasmosis?
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chorioretinitis, hydrocephalus, intracranial calcifications.
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Treatment for toxoplasmosis?
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Sulfa-based antibiotics.
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What does African trypanosomiasis cause?
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African sleeping sickness
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What does American trypanosomiasis cause?
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Chagas disease
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How does the Tsetse fly acquire Trypanosoma?
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It acquires a trypomastigote from human blood when it feeds. The parasite then becomes infectious and will infect the next host that the fly bites.
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Where do the vast majority of Trypanosomiasis cases occur in Africa?
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DRC
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Which trypanosomiasis progresses more quickly, West African or East African?
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East African
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What does the early stage of African Trypanosomiasis present as?
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Chancre at bite site, cervical lymphadenopathy, fever, cachexia.
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What does Trypanosoma do later in the progression of African disease?
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It invades the CSF and causes many CNS symptoms. Deterioration occurs until the patient is in a stuporous state and death occurs because the person is too stuporous to eat.
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What is the primary method of immune evasion by trypanosoma?
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It has 1000 different Variant Surface Glycoproteins (VSG) genes. It switches them on and off frequently and the genetic region undergoes recombination.
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What Trypanosoma causes American trypanosomiasis?
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Trypanosoma cruzi
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How does Trypanosoma cruzi get transmitted to humans?
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The bug defecates on the host's skin, and parasites in the feces can enter through the bite wound or a mucous membrane.
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Is acute American trypanosomiasis a fatal disease if untreated?
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In most people it is self-limiting. 1% will have serious cardiac problems.
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How long after acute American trypanosomiasis do chronic symptoms develop (sometimes)?
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10-20 years
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Describe the infection cycle after Plasmodium is transmitted by mosquito.
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The parasites travel to the liver where they invade hepatocytes and mature for 1-2 weeks. They emerge and begin an asexual cycle inside RBCs. They lyse the cells to infect more RBCs.
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Which Plasmodium species have dormant periods?
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vivax and ovale
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What is the periodicity of RBC lysis in Vivax, ovale, malariae, and falciparum species?
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48 hours for Vivax, ovale, and falciparum. 72 hours for malariae
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Why are malaria symptoms phasic?
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They occur in sync with lysis of RBCs
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Which Plasmodium species causes the most severe disease? Why?
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Falciparum because the parasites cytoadhere to blood vessels in the microvasculature, which can cause multi-organ failure.
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Why do you generally seem most malaria cases (and certainly most severe cases) in children in Sub-Saharan Africa?
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The parasite is so endemic that adults have been constantly exposed to it for their lifetimes. They develop partial immunity that makes their infection either asymptomatic or mild.
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How does falciparum infection cause low birth weight in pregnant women?
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It cytoadheres to the placenta. This only affects women on their first pregnancy. After that they have partial immunity.
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What is the treatment for P. vivax infection?
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Chloroquine then primaquine to clear the hypnozoites
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What is the treatment for P. falciparum infection?
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Artemisinin Combination Therapies (ACT)
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What is a major contraindication for Primaquine use for P. vivax?
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Its use will cause hemolytic anemia in patients with G6PDH deficiency
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