What is cyclospora? Diarrhoea symptoms, foods linked to US outbreak

United States health officials are investigating a growing cyclospora outbreak after infections surged across the country this year.

Since May ۱, the Centers for Disease Control and Prevention (CDC) has confirmed ۱,۶۴۵ domestically acquired cases and is reviewing more than ۵,۱۰۰ additional reports to determine whether they are also linked to the outbreak.

The agency expects the number of infections to continue rising through August. While the illness is rarely life-threatening, it can cause prolonged gastrointestinal symptoms and is usually treated with antibiotics.

Here is what we know about the virus and the outbreak:

What is cyclospora?

Cyclospora is a tiny parasite that can only be seen under a microscope. It causes an intestinal illness called cyclosporiasis. Once inside the body, cyclospora infects the intestines and can cause symptoms that last for weeks if they are not treated.

Unlike many other foodborne illnesses, cyclospora does not usually spread directly from one person to another. After leaving the body in a bowel movement, the parasite needs several days to weeks in the environment before it can infect someone else.

Cyclospora infections are less common than illnesses caused by bacteria such as salmonella or E coli. However, outbreaks in the US have become more frequent over the past decade. Health experts say this is likely due to better testing and environmental conditions, such as warmer weather, that help the parasite survive.

How do people get infected with cyclospora?

According to the CDC, people become infected with cyclospora after eating food or drinking water contaminated with the parasite, usually when human waste enters the food or water supply.

Fresh produce, including leafy greens, herbs and berries, has been linked to past outbreaks because these foods are often eaten raw and may be exposed to contaminated irrigation or washing water.

Health officials have not yet identified the source of the current US outbreak. The FDA is tracing several types of fresh produce through the supply chain to determine where the contamination occurred.

The investigation includes lettuce identified by Michigan health officials as a possible source, although authorities say no specific produce item, grower or supplier has been confirmed as the cause.

As part of its investigation, the FDA is interviewing infected people about what they ate before becoming sick and is then following those foods back through distributors and suppliers, sometimes all the way to the farm where they were grown.

What foods are commonly linked to cyclospora?

In previous outbreaks, cyclospora has most often been traced to fresh fruits and vegetables that are eaten raw. Foods linked to infections include lettuce, bagged salad mixes, cilantro, basil, raspberries, snap peas, coleslaw, vegetable trays and fresh fruit mixes.

Taco Bell has reportedly removed lettuce, cilantro, pico de gallo and guacamole from the menu at some locations as a precaution while health officials investigate the outbreak.

Experts also recommend taking extra care when handling fresh produce. Washing fruits and vegetables thoroughly at home, even if they are labelled “pre-washed”, may help reduce the risk of contamination.

What are the symptoms of a cyclospora infection?

According to the CDC, symptoms of a cyclospora infection usually appear about a week after a person eats contaminated food or drinks contaminated water, although they can develop as early as two days or as late as two weeks after exposure.

The most common symptom is frequent, watery diarrhoea, but the infection can also cause loss of appetite, weight loss, stomach cramps, bloating, gas, nausea and extreme tiredness.

Some people may also experience vomiting, body aches, headaches, a low-grade fever or other flu-like symptoms. Others, particularly those who live in areas where cyclospora is common, may have no symptoms at all.

How can you prevent it?

Good food hygiene can help lower the risk of infection, although washing produce does not always remove the parasite. But experts recommend:

• Washing hands thoroughly with soap and water before and after preparing fresh fruits and vegetables.
• Rinsing all fresh produce under running water before eating, even if it is sold as “pre-washed.”
• Using a clean produce brush to scrub firm fruits and vegetables.
• Refrigerating cut, peeled or cooked fruits and vegetables within two hours to help keep them safe to eat.

Where has it spread in the United States?

According to the latest CDC data, cyclospora infections have been reported in more than ۳۰ US states this year, with the largest number of cases concentrated in the Midwest and Northeast.

Michigan has reported the highest number of infections, with between ۵۰۱ and ۹۰۰ cases. Other heavily affected states include New York (۱۶۱-۳۰۰ cases), North Carolina (۸۱-۱۶۰), and Illinois, Indiana, Kentucky, New Jersey and Texas (۳۱-۸۰ each).

Cases have also been reported in Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Florida, Georgia, Iowa, Kansas, Louisiana, Maryland, Massachusetts, Minnesota, Nebraska, New Hampshire, Ohio, Oklahoma, Pennsylvania, Rhode Island, Tennessee, Utah, Virginia, Washington, West Virginia and Wisconsin, although many of those states have recorded fewer than ۳۰ infections.

What’s the current situation?

Cases seem to be surging in and around southeastern Michigan. But this is not being treated as a national health emergency yet.

There’s no evidence that the parasite has evolved to become more infectious, said Dianna Blau, the CDC’s acting parasitic diseases branch chief.

Thousands of cyclospora illnesses are reported in the US each year, and it’s not yet clear how unusual this year will be, she added. That said, the case total so far is four times higher than at the same point last year, according to current CDC national data, which lags dramatically from what’s being reported by the states.

Michigan appears to be suffering the worst of it, but the state’s aggression in investigating and reporting cases may be “part of the reason why this looks like a Michigan problem”, Natasha Bagdasarian, Michigan health department’s chief medical executive said.

How long does a cyclospora infection last?

Without treatment, the illness can last from several days to a month or longer.

Diarrhoea may improve and then return, while fatigue can continue even after other symptoms have disappeared.

How is cyclospora diagnosed?

A cyclospora infection is diagnosed by testing a stool sample for the parasite.

Because the parasite is not always present in large enough amounts to be detected, a single test may not be enough. Doctors often ask patients to provide several stool samples collected over different days to improve the chances of finding the infection.

Laboratories use specialised tests to identify the parasite, including microscopic examination and molecular methods such as polymerase chain reaction (PCR), which detects cyclospora’s genetic material in a stool sample.

What antibiotic is used to treat cyclospora?

According to the CDC, the standard treatment for cyclospora infection is the antibiotic trimethoprim-sulfamethoxazole (TMP-SMX), which is sold under brand names such as Bactrim and Septra.

The medication is usually taken for seven to ۱۰ days, although people with weakened immune systems, including those living with HIV, may need a longer course of treatment.

Most healthy people eventually recover even without antibiotics. However, without treatment, the illness can last for several weeks or even longer, and symptoms such as diarrhoea may return after disappearing.

What should you do if you think you have cyclospora?

Because cyclosporiasis can cause prolonged diarrhoea, it is important to replace lost fluids and keep eating when possible. Drink water, broth or electrolyte drinks, and avoid alcohol and caffeinated beverages, which may worsen dehydration.

Eating small amounts at a time may be easier if you have little appetite. Anyone prescribed antibiotics should take the full course exactly as directed, even if symptoms improve before the medication is finished.