Protozoa Infections

Protozoa Infections

Unicellular eukaryotic organisms – part of animal kingdom

Malaria:
• caused by Plasmodium faliciparum, P. vivax, P. ovale and P. milariae; transmitted by bite of anopheline mosquitoes; 7-14 day incubation; most will present within 2 months
• WHO campaigns have reduced incidence; over 2000 cases annually in Britain (mostly travellers)
• multiples in red blood cells  haemolysis, stasis of red blood cells and release of cytokines
• mainly in hot wet climates of tropics and subtropics
• prodrome of headache, muscle aches, headache, anorexia  progresses to sudden coldness, rigor, high fever, vomiting, sweats
• 1% fatal (mostly children); other complications – cerebral infection; hypoglycaemia; renal failure; pulmonary oedema
• treatment – most now resistant to chloroquine; primaquine; quinine; pryimethamine; mefloquine

Amoebiasis:
• due to Entamoeba histolytica – intestinal amoeba spread between humans by its cyst
• causes dysentery – up to several years after infection; diarrhoea (mild at first) that progresses to being profuse and bloody
• responds quickly to metromidazole

Giardiasis:
• caused by Giardia intestinalis
• more common in tropics
• 1-3 week incubation  diarrhoea, abdominal pain, weakness, anorexia, nausea, vomiting
• treatment – tinidazole, metronindazole

Toxoplasmosis:
• caused by Toxoplasma gondii. Route is via GI tract, lungs or broken skin; from cats (hosts) or infected food
• most infections are asymptomatic

Leishmaniasis:
• due to Leishmania protozoa spread by sandflies in Africa, India, South American, Middle East.
• Cutaneous leishmaniasis – lesion develops at site of bite – starts as itchy papule  crust falls off  ulcer; most heal
• Mucocutaneous leishmaniasis – primary skin lesion spreads to mucosa of nose or mouth; can result in pneumonia
• Visceral leishmaniasis – results in hyperpigmentation of face, hands, feet and abdomen); 52% present with burning feet – other presenting features include fever, splenomegaly, weight loss, sweats, fatigue, decreased appetite, cough

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