AN OUTBREAK OF TETRODOTOXIN POISONING FROM CONSUMING HORSESHOE CRABS IN SABAH

The horseshoe crab (Carcinoscorpius rotundicauda) is consumed by those residing near the coastal areas of Kota Marudu District in Malaysia, as it is considered a delicacy. During June to August, 2011 thirty cases of tetrodotoxin poisoning were reported from Kota Marudu District following ingestion of horseshoe crabs caught in Kota Marudu Bay. The purpose of this study is to describe this case series in order to determine risk factors to prevent further outbreaks. There were six confirmed and 24 probable cases of tetrodotoxin poisoning identified in the study area during the study period as diagnosed by clinical presentation and laboratory findings. Symptoms included dizziness (80%), circumoral and lingual numbness (80%), hand and feet numbness (63.3%), nausea and vomiting (30%) and weakness and difficulty in breathing (26.6%). Three cases (10%) died while 27 cases recovered. Forty-seven percent of the cases had onset of symptoms within 30 minutes of ingestion and 14% 31-60 minutes after ingestion of horseshoe crab meat. Urine samples were collected from the cases, while horseshoe crabs, cockles and sea water from the epidemic area were also taken for analysis. Tetrodotoxin was detected in the urine of six cases; the highest concentrations recorded were among the three cases who died. High tetrodotoxin concentrations were found in the hepatic cecum and eggs of the tested horseshoe crabs. Dinoflagellates were not detected in the sea water or cockle samples. Intensive health education was initiated quickly to stop other members of the Marudu Bay community from consuming the horseshoe crabs. This is the first documented epidemic of tetrodotoxin poisoning in Sabah.