Cyclospora infection
Cyclospora is a single-celled parasite that reaches people through water and raw greens and causes a long-running watery diarrhoea.
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Medicines commonly prescribed for Cyclospora infection
For informational purposes only. Always consult a doctor before using any medicine.
Dosage form: TABLET, 160 mg trimethoprim; 800 mg sulfamethoxazoleActive substance: sulfamethoxazole and trimethoprimManufacturer: Teofarma S.R.L.Prescription requiredDosage form: TABLET, 20 trimethoprim; 100 mg sulfamethoxazoleActive substance: sulfamethoxazole and trimethoprimManufacturer: Teofarma S.R.L.Prescription requiredDosage form: TABLET, 80/400 mg/mgActive substance: sulfamethoxazole and trimethoprimManufacturer: Teofarma S.R.L.Prescription required
Cyclospora is a single-celled parasite that reaches people through water and raw greens and causes a long-running watery diarrhoea. Two things about it are worth knowing. First, about a week passes between swallowing it and the first symptoms, so by the time you are ill the link with the trip has slipped out of view. Second, left alone it drags on for weeks, easing off and coming back, whereas on the right treatment it stops within a couple of days. The whole difference between those two stories is whether anybody thinks to look for the parasite in a stool sample.
Where it comes from
You catch it by swallowing microscopic cysts of the parasite in water, or in food that has picked them up from faecal contamination. Usually that means fresh herbs, salad leaves, berries and fruit rinsed in water that was not clean, plus ice, tap water and drinks made up with it.
Cyclospora has one peculiarity that explains a great deal. The cysts leave the body immature: to become infectious they need several days, sometimes a couple of weeks, in a warm damp environment. From that follows the key point — you cannot catch it from an ill person. Not through hands, not through a shared toilet, not by nursing them. If several members of a household go down at once, they did not pass it to each other: they shared a meal or a bottle of water.
The parasite is common in warm climates — Central and South America, southern and south-eastern Asia, the Middle East and Africa — and in many of those places cases rise during the rainy season. Travel is not essential, though: outbreaks tied to imported berries and fresh herbs turn up in Europe and North America, so "I haven't been anywhere" does not rule the diagnosis out.
One more point: chlorinating water does almost nothing to cyclospora. Its cysts are tough and survive the treatment that deals with most bacteria, so tap water in an affected region is not made safe by being chlorinated.
How the illness runs
The first signs appear roughly a week after infection — sometimes after two days, sometimes after two weeks. The start is usually abrupt: frequent watery stools, often almost explosive.
- repeated watery diarrhoea, in some people up to ten times a day;
- a sharp loss of appetite and visible weight loss — two or three kilograms over a few weeks is not unusual, sometimes more;
- cramping, bloating and a lot of wind;
- nausea, sometimes a mild fever and aching muscles;
- heavy tiredness that outlasts the diarrhoea itself.
Vomiting is uncommon and blood in the stool does not occur at all — if there is blood, another cause is looked for. The giveaway feature is the way it comes in waves. Two or three better days, the person decides it is over, and it all returns. Untreated in an adult it can run on for a month or longer. Some of those infected notice nothing at all, particularly people who live in those regions permanently.
Once the diarrhoea has stopped, dairy can still cause bloating and gurgling for another two or three weeks: the gut temporarily stops coping with lactose. It settles by itself, though it frightens people who read it as the illness coming back.
Signs that will not wait
Cyclospora infection itself is not among the deadly ones, but dehydration is always dangerous, and something quite different sometimes hides behind "I ate something bad on holiday". Get seen the same day if any of the following applies:
- passing little urine and it is dark, dizziness on standing, dry mouth, sunken eyes;
- fluids will not stay down — every sip comes straight back;
- in a child: no tears when crying, listlessness, drowsiness, refusing to drink, a sunken fontanelle in a baby;
- blood in the stool, fever with shivering, severe pain fixed in one spot in the abdomen;
- diarrhoea going past two weeks, or weight that keeps falling.
Fever after the tropics deserves a paragraph of its own. Any temperature that rises within a few months of a trip to a country where malaria occurs counts as malaria until a blood test says otherwise. In the first days it looks like a gut infection: weakness, aches, sometimes diarrhoea and vomiting. The difference is that tropical malaria kills within days. So with a fever after a trip like that, do not wait for Monday — see a doctor and say first of all where you were and when you came back.
Seek help earlier and more insistently than usual if your immune system is weakened, whether by HIV, a transplant, chemotherapy or medicines that suppress immunity: in those patients the infection lasts longer, hits harder and can involve the bile ducts. The same goes for pregnancy, small babies and older people.
How it gets found
Here is the main trap. An ordinary stool culture looks for bacteria and does not see cyclospora at all. The standard "ova and parasites" microscopy misses it often too: the cysts are small, pale and do not take up routine stains. The test therefore has to be asked for specifically.
- tell the doctor and the laboratory that you have travelled, naming the country and the dates — without that the right test simply is not ordered;
- cyclospora is picked up by a special stain, by the way it glows under ultraviolet light, or by molecular testing; the last of these is the most reliable and checks for a dozen other organisms at the same time;
- the parasite is shed unevenly, so it is not one sample but several on different days;
- if nothing turns up and the diarrhoea continues, the tests are repeated and giardia, cryptosporidium and amoeba are checked as well — they look similar and are treated differently.
What treatment involves
Fluid comes first. Heavy stools take salts as well as water, so drinking plain water does not solve it: what is needed are oral rehydration sachets from the pharmacy, taken in small sips very often. Eat whatever you can tolerate; there is no point in starving yourself, though dairy is best postponed for a few days.
Unlike most travellers' diarrhoea, this infection has a specific medicine — a combined sulphonamide antibiotic, co-trimoxazole. It works dependably, and in most people the stools settle within a day or two. The regimen and its length are set by the doctor, and the course is longer if immunity is impaired. Where there is an allergy to sulphonamides, fall-back options exist but work less reliably, and that choice belongs to the doctor too.
One practical consequence is worth knowing in advance: the antibiotics travellers carry "just in case" for diarrhoea do not cover cyclospora. If you have taken such a course and felt no better, that does not mean treatment is pointless — it is a reason to send off a sample.
Medicines that slow the bowel cut the number of trips to the toilet for a while but do not remove the parasite, and with fever or blood in the stool they are not taken at all. There is no need to isolate the person who is ill: they are not infectious to anyone around them.
What genuinely lowers the risk on a trip
General caution helps little; a few specific habits help a lot.
- drink bottled, boiled or disinfected water and clean your teeth with it;
- skip ice — it is nearly always made from tap water;
- eat food that is thoroughly cooked and served hot: heat destroys the parasite reliably;
- choose fruit you can peel yourself;
- on that kind of trip, leave raw salads, leafy greens, coriander, basil and fresh berries alone;
- dairy only if pasteurised and in sealed factory packaging.
An honest word about washing: it lowers the risk but does not remove it. The cysts cling well to the uneven surface of leaves and berries and shrug off chlorine and household disinfectants; freezing is no answer either. Heat is the only thing that works dependably. That is why "I'll wash it well" is weaker advice than "I'll peel it myself" or "I'll have it hot". Handwashing does little against this particular infection, but a great deal against ten others.
Online consultation
Remotely you can settle the main question: whether this is an ordinary upset that will pass in a couple of days or a case that needs stool tests and treatment. The doctor goes through where you were and what you ate, how long it has been going on and how it behaves, says which test to ask the laboratory for and how many samples to send, explains how to rehydrate, and judges whether the medicines you have already taken could have helped. It is also a convenient way to discuss the bloating left behind after recovery. The signs listed above are not handled through a screen: with dehydration, or with a fever after the tropics, you need to be examined in person the same day.
This material is for information only and does not replace medical advice.
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