subject: Cryptosporidiosis clinical features and management [print this page] Cryptosporidiosis clinical features and management
Cryptosporidiosis is an infection of the gastrointestinaltract with the sporozoan parasite Cryptosporidium. Itcauses enteritis in humans and a range of other animals. Itis a zoonosis with a worldwide distribution.Its life cycle is complex, with asexual and sexual cycles.Infection is by the faecal-oral route. Ingested oocystsare disrupted in the intestinal lumen, liberating foursporozoites which enter the apical regions of intestinalcells within a membrane-bounded vacuole. Trophozoitesdevelop from the sporozoites and undergo asexual reproduction.Merozoites liberated by schizogony can undergofurther asexual cycles, or become gametocytes which fuseto form oocysts which are passed in the faeces.
Transmission and epidemiology Many reports recognized this organism as a gut pathogencausing persistent watery diarrhoea in immunosuppressedpatients, especially those with AIDS. Other studies showedthat Cryptosporidiosis was associated with diarrhoea in4-9% of otherwise healthy children and adults. Childrenat nursery school may transmit infection person to person.Susceptible animals include calves, lambs, goats andbirds, although a history of contact with animals is oftenabsent.
Clinical features An acute watery diarrhoeal illness, often with offensivestools, is the usual history. There may be fever and vomiting.The disease is self-limiting, with a median duration ofabout 12 days, but prolonged diarrhoea with weight lossoccurs in patients with humoral and cellular immunodeficiencystates, especially AIDS.
Diagnosis and management Faecal smears stained by the modified Ziehl-Neelsen techniqueshow the pinkish-red-staining oocysts. Other formsof the parasite are seen at the luminal surface of enterocytesin intestinal biopsies.In most patients the disease is self-limiting and symptomsresolve spontaneously in 10-12 days. There is noeffective drug therapy for the chronic infection seen inAIDS patients though diarrhoea may regress with theinstitution of effective anti-retroviral treatment. Rehydration,nutritional support and symptomatic treatment maybe needed.Handwashing is the most important factor in limiting thespread of infection by the person-to-person route.
