Food-borne tropical disease outbreak strikes the US

by Kausik Datta, The Conversation

A food-borne illness is spreading quickly through the United States, an investigation by the Centers for Disease Control and Prevention (CDC) has revealed. The disease, called cyclosporiasis, is common to tropical and subtropical regions. While occasional outbreaks have been recorded since early 1990s in the US, the current spread of the disease has been swift and wide.

Three small outbreaks of cyclosporiasis were reported in North America during 1990-95, and major outbreaks have been recorded since 1996. The disease made its way through fresh produce of raspberries, lettuce, basil and snow peas, which were mostly imported from countries where the disease is endemic. Cyclosporiasis has been found in Ghana, Peru, Guatemala, Egypt, Turkey, Nepal and Haiti.

More than 1100 sporadic cases of confirmed cyclosporiasis occurred during 1997-2008, involving 12 US states. About a third of these were thought to have been associated with international travel to endemic regions.

So far 2013 has seen the biggest outbreak. From June to August this year, an unusually large number of cyclosporiasis reports were recorded by the CDC, involving more than 600 individuals from 25 states, with high numbers in Texas, Iowa, and Nebraska.

Investigations by health officials revealed the possibility of two outbreaks. Cases in Iowa and Nebraska were associated with restaurants, and involved a salad mix (iceberg and romaine lettuce, red cabbage, carrots) sourced from the Mexican processing facility of a group of farms. Cases in Texas were associated with uncooked coriander sourced from Puebla, Mexico.

The outbreak of cyclosporiasis in 2013 in the US. Credit: CDC

Human cyclosporiasis is a disease caused by the single-celled parasite Cyclospora cayetanensis. Although there are about 18 different species of Cyclospora currently known, four appear to be specific to non-human primates. Only Cyclospora cayetanensis has been discovered in humans. Attempts to create non-human animal models of C. cayetanensis infection have been unsuccessful, suggesting host-specificity.

The transmission of this parasite occurs via what is referred to as the "fecal-oral route". In excreted fecal matter, Cyclospora exists in the form of oocysts (a thick-walled structure containing immature, dormant parasite spores), a product of sexual reproduction of the parasite. These are not infectious, but are highly resistant to common disinfectants used in food-processing industries.

Within two weeks, the spores mature – making the oocysts infectious. Neither the natural environments of this process, nor the exact manner of transmission, are yet known, but contamination of water and food (such as raw produce) with oocyst-containing fecal matter likely contributes to the dissemination. Risks of infection increases via the common factors – consumption of untreated food or water, lack of adequate sanitation and the presence of animals in the house.

This parasite primarily targets the small intestines. An infection often causes gastro-intestinal symptoms, such as diarrhea, abdominal cramping, loss of appetite, and bloating. The infected may also suffer from nausea, fatigue, weight-loss and sometimes fever. In absence of proper treatment, some of these symptoms may continue for weeks, while some may be temporarily relieved, only to recur.

The growth of cyclosporiasis from an oocyst to free sporocysts, which can go on to infect other cells. Credit: CDC

The good news is that the infection is not generally life-threatening and people with healthy immune systems may not require treatment. However, in children and in the elderly, as well in individuals with weak immunity (such as AIDS or cancer patients), untreated cyclosporiasis may cause severe, and occasionally fatal, illness.

Currently the drug of choice for Cyclospora infection is Trimethoprim-sulfamethoxazole. According to the CDC, proper storage, washing and cooking of fresh vegetables and fruits should keep the in check.

add to favorites email to friend print save as pdf

Related Stories

400 now sickened in stomach bug outbreak

Aug 02, 2013

(HealthDay)—The ongoing outbreak of infection with the foodborne cyclospora parasite has now reached 400 cases and spread to 16 states and New York City, according to the latest U.S. Centers for Disease ...

More cases reported in stomach bug outbreak

Aug 19, 2013

(HealthDay News) —U.S. health officials are continuing to search for the source of a nationwide stomach bug outbreak as the number of cases has climbed to 586, with illnesses reported in 20 states.

Cases in stomach bug outbreak continue to climb

Aug 16, 2013

(HealthDay)—As U.S. health officials continue to try to track down the source of a widespread stomach bug outbreak, the number of cases continues to climb, with 576 illnesses now reported in 19 states.

CDC: U.S. patients suffering tropical infection

Jul 26, 2013

(HealthDay)—The intestinal infection cyclosporiasis is generally seen in people living or traveling in tropical or subtropical areas, but two cases brought to the attention of the U.S. Centers of Disease ...

Stomach bug outbreak cases top 500

Aug 08, 2013

(HealthDay)—As U.S. health officials continue to try to track down the source of a widespread stomach bug outbreak, the number of confirmed illnesses keeps climbing.

Recommended for you

S.Korea detects second foot-and-mouth case

11 minutes ago

South Korea on Monday reported its second case of foot-and-mouth disease in less than a week, triggering fearful memories of a devastating 2011 outbreak that forced the culling of millions of livestock.

Ebola kills Liberian doctor, 2 Americans infected

41 minutes ago

(AP)—One of Liberia's most high-profile doctors has died of Ebola, officials said Sunday, and an American physician was being treated for the deadly virus, highlighting the risks facing health workers trying ...

Hepatitis C virus genotype 1 is most prevalent worldwide

1 hour ago

In one of the largest prevalence studies to date, researchers from the U.K. provide national, regional, and global genotype prevalence estimates for the hepatitis C virus (HCV). Findings published in Hepatology, a journa ...

1 in 3000 blood donors in England infected with hepatitis E

1 hour ago

The first systematic analysis of hepatitis E virus (HEV) transmission by blood components indicates that about 1 in 3000 donors in England have HEV in their plasma. The findings, published in The Lancet, suggest that around ...

Biologic treatments for RA carry similar infection risk

1 hour ago

(HealthDay)—The risk of hospitalized bacterial infections in older rheumatoid arthritis (RA) patients is similar for rituximab or abatacept compared to etanercept, although it is higher for infliximab, ...

New oral drug regimens cure hardest-to-treat hepatitis C

1 hour ago

Two new pill-only antiviral drug regimens could provide shorter, more effective treatment options with fewer side effects for the majority of patients infected with hepatitis C, even those most difficult to treat, according ...

User comments