Cyclospora season starts each year in late May, peaks in June and July and is almost completely over by August, with rare cases at any time of year. It is a protozoan parasite that infects the upper small intestine, causing profound fatigue, loss of appetite and diarrhea.
At first the diarrhea is fairly acute for 2–3 days and may come with fever, nausea or vomiting. The illness then waxes and wanes, with some good days interspersed with days of poor appetite, fatigue and diarrhea. Untreated, it can last two to twelve weeks. Some people never get diarrhea and just have profound fatigue and loss of appetite. Children get it too, with very similar symptoms.
We used to see about 20–25 cases of Cyclospora a year at CIWEC, but cases have been declining. Risk is highest among new foreign residents. There seems to be some immunity, since long-term expatriates get it infrequently — but some people have had it in more than one season, and one or two have caught it twice in the same season. Nepalis get it too, though it most often goes unrecognized.
Treatment
In 1995, research at CIWEC confirmed that the antibiotic trimethoprim-sulfamethoxazole (Bactrim or Septra) cures the infection. No effective alternative has yet been found, though we continue to look for a treatment for people allergic to sulfa drugs.
How to avoid Cyclospora
- It's waterborne. Drinking untreated water is one way to get it. It may also be carried on food, particularly uncooked leafy vegetables such as lettuce.
- Iodine and chlorine do not kill Cyclospora. Drinking water must be boiled, or filtered with a filter designed for purifying drinking water. Household candle filters are probably not fine enough. Boiling kills it easily. People working in the field or trekking are at risk if they drink water treated only with iodine.
- Be careful with salads. The usual way of disinfecting lettuce may not work, since iodine doesn't kill the organism. It may be best to avoid uncooked or unpeeled vegetables in June, July and August.
- Swimming and bathing. Swimming pools have not been implicated. Swallowing a lot of bath water could be a risk, but ordinary bathing and showering don't seem to be.