Isosporiasis is an intestinal disease known to occur in immuno-depressed individuals. The exact incidence of isosporiasis is not evident, but Isospora Belli has been reported as the cause of diarrheal illness outbreaks in mental institutions and day-care centres. It has also been implicated in traveller's diarrhea in various endemic areas.
Virchow was the first to describe Isospora Belli in 1860. The first case of human infection with Isospora Belli (or isosporiasis) was described in 1915. It's interesting to admit that this parasite is closely related to Cyclospora, Cryptosporidium and Toxoplasma.
It's interesting to mention that the cause of isosporiasis can be not only the Isospora Belli, but also increased incidence of infection in areas with poor sanitation, increased incidence of infection in AIDS patients.
The occurrence of isosporiasis is increased in people suffering from AIDS, but it now is less common because of the widespread use of Pneumocystis carinii prophylaxis containing trimethoprim-sulfamethoxazole (TMP-SMZ). It's worth admitting that isosporiasis is considered to be the initial AIDS-defining disease in approximately 0,2% of patients with AIDS and in about 2-3% of patients with AIDS who are from Africa. In patients with AIDS who are from South America, 10% of people with chronic diarrhea have isosporiasis. In patients with AIDS who are from Haiti and Africa, approximately 7-20% of patients with chronic diarrhea are also infected with isosporiasis.
Thus, subtropical and tropical areas including Australia, Africa, the Caribbean Islands, Southeast Asia and Latin America are among endemic areas of the disease.
The basis for isosporiasis diagnosis is usually a microscopic demonstration of large, typical oocysts. For the reason these oocysts are possible to be passed intermittently and in small amounts repeated stool examinations and concentration procedures are, as a rule, required. The oocysts can be visualized by microscopy with differential interference contrast (DIC), or epifluorescence.
Isosporiasis has faecal-oral mode of transmission (through food or water contaminated with human feces). The infected person who isn't immuno-compromised usually experiences a mild and protracted illness. Otherwise - more severe disease can be present (debilitating or life-threatening). Patients with such severe cases require hospitalization.
Isosporiasis signs and distinguishing symptoms include watery, non-bloody, profuse, offensive-smelling diarrhea, which may contain mucus, anorexia, malaise, weight loss, vomiting, cramping abdominal pain, low-grade fever, in protracted cases - steatorrhea. The incubation period of the illness can range from three days to two weeks.
Isosporiasis treatment has not been defined yet. Isosporiasis is a disease which doesn't respond well to the majority of antibiotics used to treat diarrhea. Antibiotics therapy must be comprehensive and cover all likely pathogens.