Isospora belli infection in Australia

Cystoisospora belli infections in humans: the past 100 years

Cystoisospora belli is a coccidian parasite of humans, with a direct fecal-oral transmission cycle. It is globally distributed, but mainly found in tropical and subtropical areas. Many cases of C. belli infections have been reported in patients with HIV, and in patients undergoing immunosuppressive therapy for organ transplants or those treated for tumours worldwide. Unsporulated or partially sporulated oocysts of C. belli are excreted in feces. When sporulated oocysts in contaminated water or food are ingested, asexual and sexual stages of C. belli are confined to the epithelium of intestines, bile ducts and gallbladder. Monozoic tissue cysts are present in extra-intestinal organs (lamina propria of the small and large intestine, lymph nodes, spleen, and liver) of immunosuppressed humans. However, a paratenic host has not been demonstrated. Cystoisospora belli infections can be persistent, lasting for months, and relapses are common; the mechanism of relapse is unknown. Recently, the endogenous stages of C. belli were re-examined and attention was drawn to cases of misidentification of non-protozoal structures in the gallbladder of patients as C. belli. Here, we review all aspects of the biology of C. belli, including morphology, endogenous stages, prevalence, epidemiology, symptoms, diagnosis and control.

Successful therapeutic management of canine Isosporosis in puppies

Four labrador male puppies were confirmed for the Isospora spp infection by direct smear and flotation method following complains of anorexia, haematemesis and haematochezia. The puppies were treated with trimethoprime and sulphamethoxazole @ 40 mg/kg body weight in combination with metronidazole @ 10 mg/kg body weight twice daily for 5 days which was supported with fluid therapy, aniemetics and plasma expanders. All the animals showed completed clinical recovery along with clearing of faecal oocyst.

Parasitic diarrheal disease: drug development and targets

Diarrhea is the manifestation of gastrointestinal infection and is one of the major causes of mortality and morbidity specifically among the children of less than 5 years age worldwide. Moreover, in recent years there has been a rise in the number of reports of intestinal infections continuously in the industrialized world. These are largely related to waterborne and food borne outbreaks. These occur by the pathogenesis of both prokaryotic and eukaryotic organisms like bacteria and parasites. The parasitic intestinal infection has remained mostly unexplored and under assessed in terms of therapeutic development. The lack of new drugs and the risk of resistance have led us to carry out this review on drug development for parasitic diarrheal diseases. The major focus has been depicted on commercially available drugs, currently synthesized active heterocyclic compounds and unique drug targets, that are vital for the existence and growth of the parasites and can be further exploited for the search of therapeutically active anti-parasitic agents.

Biology of Isospora spp. from humans, nonhuman primates, and domestic animals

Coccidial parasites of the genus Isospora cause intestinal disease in several mammalian host species. These protozoal parasites have asexual and sexual stages within intestinal cells of their hosts and produce an environmentally resistant cyst stage, the oocyst. Infections are acquired by the ingestion of infective (sporulated) oocysts in contaminated food or water. Some species of mammalian Isospora have evolved the ability to use paratenic (transport) hosts. In these cases, infections can be acquired by ingestion of an infected paratenic host. Human intestinal isosporiasis is caused by Isospora belli. Symptoms of I. belli infection in immunocompetent patients include diarrhea, steatorrhea, headache, fever, malaise, abdominal pain, vomiting, dehydration, and weight loss, blood is not usually present in the feces. The disease is often chronic, with parasites present in the feces or biopsy specimens for several months to years. Recurrences are common, Symptoms are more severe in AIDS patients, with the diarrhea being more watery. Extraintestinal stages of I. belli have been observed in AIDS patients but not immunocompetent patients. Treatment of I. belli infection with trimethoprim-sulfamethoxazole usually results in a rapid clinical response. Maintenance treatment with trimethoprim-sulfamethoxazole is needed because relapses often occur once treatment is stopped.

Isosporiasis in the aboriginal population of Queensland

OBJECTIVE

To report on the endemicity of Isospora belli in Queensland.

DESIGN

A 10-year retrospective survey of data from routine parasitological surveillance of Queensland Aboriginal communities, by microscopic examination of preserved faecal specimens.

SETTING

The Aboriginal Health Programme of the Queensland Department of Health and Medical Services.

POPULATION

Children under 15 years of age from all the Aboriginal communities of Queensland.

RESULTS

Oocysts of I. belli were detected in 33 (0.2%) of a total of 17,642 faecal samples examined.

CONCLUSION

Isosporiasis is endemic in the Queensland Aboriginal population. It is likely to be more common than indicated, because the infection is difficult to diagnose, and the techniques used to identify the organism were not particularly sensitive. It is predicted that isosporiasis will be recognised with increasing frequency as a cause of diarrhoea in Aboriginal and white Australians who develop AIDS.

Isospora belli infection. A report of two cases in patients with AIDS

OBJECTIVE

To present the findings of Isospora belli infection in two patients with the acquired immunodeficiency syndrome (AIDS).

CLINICAL FEATURES

One patient was part Aboriginal, the other an immigrant recently arrived from Peru. Both men were infected with the human immunodeficiency virus (HIV). They presented with watery diarrhoea, one with severe weight loss. Isospora belli oocysts were detected in multiple faecal specimens from both patients. One patient had a concomitant infection with Cryptosporidium sp.

INTERVENTION AND OUTCOME

There was a rapid response to treatment with cotrimoxazole (960 mg, four times a day for 10 days). A complete response was obtained in the patient with concurrent cryptosporidiosis. The diarrhoea recurred after cessation of treatment, necessitating maintenance therapy.

CONCLUSION

Although Isospora belli is an uncommon cause of gastroenteritis in Australia, it is increasingly recognised as a cause of diarrhoea in travellers, immigrants from endemic areas and immunocompromised people. It has also been reported in the Aboriginal community; this article reports the first case of AIDS-related isosporiasis in an Aborigine. It is likely that both patients acquired Isospora belli before they become HIV seropositive.