Cyclospora parasite spreads in the US – hundreds of infections in more than 30 states

Symptoms and course of the disease

The US disease control agency describes Cyclospora as a pathogen that affects the small intestine and usually causes watery diarrhea. The agency puts it starkly: "Cyclospora befällt den Dünndarm und verursacht in der Regel wässrigen Durchfall mit häufigem und manchmal explosionsartigem Stuhlgang." If left untreated, the illness can, according to the CDC, "von wenigen Tagen bis zu mehr als einem Monat andauern."

Michigan at the center of the outbreak

Epidemiologist and scientist Caitlin Rivers of the Johns Hopkins Center for Health Security locates the geographical focus of the outbreak in the state of Michigan. "Darin schreibt sie, dass das Zentrum des Ausbruchs der US-Bundesstaat Michigan sei; der Parasit habe sich aber bereits über viele weitere Staaten ausgebreitet." Rivers had recently warned about the parasite in a newsletter. Caitlin Rivers, epidemiologist and scientist at the Johns Hopkins Center for Health Security, had recently warned about the parasite in a newsletter.

In Michigan, the outbreak is particularly pronounced. The state's health authority announced on Friday that more than 1,500 cases had already been registered. "In der Regel gibt es laut der Behörde dort etwa nur 50 Fälle pro Jahr." This puts the current number far above the seasonal average.

Situation in New York

In New York as well, the number of cases has risen significantly since May. In the state of New York, for example, 470 cases have been recorded since May 1, according to the local health authority. The authority there does not, however, see this as an unusual deviation from the usual seasonal figures.

In total, reports have come in from 31 of the 50 US states. "Das allein ist aber kein Beleg für jeweils einen richtigen Ausbruch," it says on the matter. The CDC also emphasizes: "Was die Quelle für den aktuellen Ausbruch ist und ob die Fälle zusammenhängen, ist noch ungeklärt." Authorities are therefore so far speaking cautiously of a cluster, not of a confirmed single outbreak.

Transmission routes and at-risk foods

According to the CDC, Cyclospora is not transmitted directly from person to person. "Der Parasit namens Cyclospora cayetanensis wird dabei normalerweise nicht direkt von Mensch zu Mensch, sondern über mit Fäkalien kontaminierte Lebensmittel oder Wasser übertragen, heißt es von der zentralen Gesundheitsbehörde der Vereinigten Staaten CDC." Typical outbreak sources are fresh fruits and vegetables.

The parasites are excreted in stool as oocysts – thick-walled spores that can survive outside their host for extended periods. When freshly excreted, however, they are not infectious. "Deswegen sind sie frisch im Stuhl nicht infektiös und eine direkte Übertragung von Mensch zu Mensch passiert eher nicht."

Only when the oocysts mature – usually in the environment – can they trigger infections again. "Sind Nahrungsmittel damit kontaminiert, können die Parasiten aber in den Dünndarm eindringen." They then enter the human body via contaminated water or unwashed food.

Diagnosis and treatment

Cyclospora outbreaks typically occur in summer and are linked to the consumption of fresh fruits and vegetables. These include raspberries, blackberries, strawberries, blueberries, basil, cilantro, sugar snap peas, snow peas, prepared vegetables, and various salads. Authorities recommend washing these products thoroughly or refraining from eating them if warnings are in place.

Detecting an infection is complex. Patients must submit multiple stool samples to reliably identify the pathogen. This can delay the recording of actual case numbers. A single negative stool sample does not rule out an infection.

Recommendations from authorities

The CDC advises seeking medical help if corresponding symptoms appear – particularly in order to prevent dehydration. It is also important to take in sufficient fluids when diarrhea occurs. The infection itself is usually treated with antibiotics.

While authorities continue to monitor the situation, experts such as Caitlin Rivers are warning of a possible further spread. The CDC has stepped up surveillance and is examining whether individual case clusters are linked to one another. Consumers should continue to pay attention to hygiene rules and warning notices.

US health authorities recommend particular caution when handling fresh fruits and vegetables. Products should be washed thoroughly before consumption, avoided if recalls or warnings are known, and in affected areas, travelers should drink only boiled or bottled water.

Even though the pathogen is rarely fatal, it can become dangerous for certain at-risk groups. Small children, older people, and individuals with weakened immune systems are particularly susceptible to a severe course. Medical advice should be sought if diarrhea persists.