|
Isosporiasis
and cyclosporiasis are infections with the coccidian protozoa Isospora belli and Cyclospora cayetanensis, respectively. Symptoms
include watery diarrhea with accompanying GI and systemic complaints.
Diagnosis is by detection of characteristic oocysts in stool or
intestinal biopsy specimens. Treatment is usually with trimethoprim-sulfamethoxazole.
The life cycles of I. belli and C. cayetanensis are similar to that of Cryptosporidium, except that oocysts must sporulate before becoming infective. Human isosporiasis and cyclosporiasis are most common in tropical and subtropical climates. Transmission is by the fecal-oral route via contaminated food or drink. In North America, outbreaks of C.
cayetanensis have been caused by ingestion of imported raspberries from Guatemala.
Symptoms,
Signs, and Diagnosis
The primary complaint is acute, nonbloody, watery diarrhea, with fever, abdominal cramps, nausea, anorexia, malaise, and weight loss. In immunocompetent people, the illness usually resolves spontaneously but can last weeks.
In hosts with depressed cell-mediated immunity as in AIDS, isosporiasis and cyclosporiasis may cause severe, intractable, voluminous diarrhea resembling cryptosporidiosis. Extraintestinal disease in patients with AIDS may include cholecystitis and disseminated infection.
Diagnosis is by detection of oocysts by microscopic examination of the stool. Detection is facilitated by staining stool samples with modified acid-fast stain. Multiple stool specimens may be needed. Diagnosis is sometimes made only when intracellular parasite stages are detected in biopsies of intestinal tissue. In isosporiasis, the stool may contain Charcot-Leyden crystals (hexagonal, double-pointed, and often needlelike crystals) derived from eosinophils. Unlike other protozoan infections, peripheral blood eosinophilia may also occur with I. belli.
Treatment
Treatment of choice for both isosporiasis and cyclosporiasis is double-strength trimethoprim-sulfamethoxazole (TMP-SMX) 160 mg TMP and 800 mg SMX po bid for 10 days. Children are given 5 mg/kg TMP and 25 mg/kg SMX bid. In patients with AIDS, higher doses and longer duration may be needed. Treatment of acute infection is usually followed by long-term suppressive therapy in those with AIDS. Ciprofloxacin 500 mg po bid for 7 days has also been used in isosporiasis and cyclosporiasis but appears to be less effective then TMP-SMX.
Prevention is as for cryptosporidiosis.
Last full review/revision November 2005
Content last modified November 2005
| 
