In a new report, public health investigators describe a cluster of ciguatera fish poisoning cases in which one of the main symptoms was painful sexual intercourse.

Ciguatera is a neurotoxin that may contaminate certain predatory ocean fish, such as barracudas, groupers and moray eels, the investigators note in this week's Morbidity and Mortality Weekly Report. Humans develop ciguatera poisoning when they eat the fish contaminated with the ciguatoxin, which is very heat-resistant and can't be destroyed by conventional cooking. Up to 50,000 cases of ciguatera fish poisoning occur each year and the problem is endemic in tropical and subtropical areas of the Indian Ocean, Caribbean and Pacific basin.

Symptoms of ciguatera fish poisoning typically include gastrointestinal symptoms, such as nausea, vomiting, abdominal cramps or diarrhea. Neurologic symptoms, however, may also be present and include reversal of hot and cold sensation, fatigue, muscle pain, itching, and tingling.

In 2007, nine cases of ciguatera fish poisoning occurred in North Carolina, lead investigator Dr. R. Langley, from the North Carolina Department of Health and Human Service, and colleagues note. Five patients had neurologic symptoms only, six had reversal of hot and cold sensation, and three patients had symptoms that lasted for over 6 months.

Of the seven patients who were sexually active, six complained of painful sexual intercourse, the report indicates.

The two men in this group described painful ejaculation, and the four women reported "a burning sensation during intercourse and 15 minutes to 3 hours after intercourse." One of the men reported that the effect lasted for 1 week, and two of the women said they were affected for 1 month.

The investigation revealed that all of the patients had consumed contaminated amberjack, which had been sent to a local fish market by a distributor in Atlanta.

As ciguatera fish poisoning "becomes more common in nontropical areas of the world, clinicians need to be aware of its manifestations and how to manage it," according to the report. Intravenous mannitol has been used for many years to manage the neurologic symptoms. There is also evidence that amitriptyline is useful in this regard.