Cyclospora season starts each year in late May, peaks in June and July and finishes almost completely by August with a rare case occurring at any time of the year. It is a protozoan parasite that infects the upper small intestine causing profound fatigue, loss of appetite, and diarrhea. Initially, the diarrhea is fairly acute for 2-3 days and may be accompanied by fever, nausea or vomiting. The disease then has a waxing and waning course with some good days interspersed with days of anorexia, fatigue and diarrhea. Untreated, the infection can last from two to twelve weeks. Some people never get diarrhea and just have profound fatigue and loss of appetite. Children get this infection too and the symptoms are very similar to symptoms in adults.
The risk of getting ill is fairly high in the Cyclospora season, 7-11% of all expatriates living in Kathmandu during this season are affected each year. The risk is highest among new foreign residents: in a study of 77 new foreign residents (living in Nepal for less than one year at time of enrollment), 32% developed Cyclospora during the first season that they were exposed. There does seem to be some immunity to Cyclospora infections since long- term expatriates get the disease infrequently. However, some individuals have had the disease in more than one season and 1-2 persons have acquired it twice in the same season.
Research confirmed that the antibiotic trimethoprim-sulfamethoxazole (also known as Bactrim or Septra) was effective at curing this disease. An alternative to this treatment has not been found although we continue to search for new therapy for Sulfa-allergic individuals. Here are some tips to help avoid Cyclospora:
1. Cyclospora has been proven to be waterborne, which means that drinking untreated water is one way that you can get the infection. It may also be in food, particularly leafy vegetables that are not cooked, such as lettuce.
2. Iodine and chlorine do not kill Cyclospora. This means that drinking water must be boiled, or filtered with a special filter designed for purifying drinking water. The candle filters in your kitchen are probably not small enough to eliminate Cyclospora. The organism is easily killed by boiling. People working in the field or trekking will be at risk if they drink water that is only treated with iodine.
3. The usual way of disinfecting lettuce for salads may not be effective at preventing Cyclospora infection, since iodine does not kill the organism. It may be best to avoid uncooked or unpeeled vegetables in salads during this season.
4. Swimming in swimming pools has not been implicated as a risk factor for getting Cyclospora. Drinking a large quantity of bath water could be a risk, but ordinary bathing and showering does not seem to be a specific risk for getting ill.