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Toxic Hypoglycemic Syndrome -- Jamaica, 1989-1991

In January and February 1991, the health officer in the parish of St. Ann, Jamaica, received reports of eight persons with toxic hypoglycemic syndrome (THS), an illness associated with consumption of unripe ackee fruit and, possibly, renta yam; two cases were fatal. On July 25, the Jamaican Ministry of Health (JMH) contacted CDC for assistance in investigating the continued occurrence of THS; the collaborative JMH and CDC epidemiologic investigation focused on characterizing the epidemiology of THS in Jamaica and assessing the role of ackee fruit, renta yams, and other factors.

A case of THS was defined as a clinician's diagnosis of hypoglycemia in any person who was examined at eight public hospitals from January 1, 1989, through July 31, 1991, and who had a hospital discharge diagnosis or cause of death listed as Jamaican vomiting sickness, ackee poisoning, renta yam poisoning, or toxic hypoglycemia of unknown etiology. Cases of hypoglycemia associated with insulin use, insulinoma, or Reye syndrome were excluded. Medical records were reviewed at eight public hospitals in six of the 14 parishes in Jamaica; the nutritional status of patients could not be assessed.

The investigation identified 38 patients, including eight who died, who had illnesses meeting the case definition. Reported symptoms included vomiting (77%), coma (26%), and seizures (24%). Seven (18%) patients had laboratory-confirmed hypoglycemia before intravenous glucose treatment was initiated. Of the 38 cases of THS, 28 (74%) (including six deaths) were attributed to ackee poisoning, nine (24%) (including two deaths) to idiopathic toxic hypoglycemia, and one (3%) to renta yam poisoning.

Patients resided in seven parishes. Twenty-one (55%) cases occurred in 1991; of these, eight were in St. Ann parish. Most (29 (76%)) cases occurred during January-March (Figure 1). For the case-finding period, the average annual rate of THS in the seven parishes was 1 per 100,000 persons per year. Twenty-eight (74%) of the patients were aged less than 15 years; the rate of THS was 2 per 100,000 persons per year among those aged less than 15 years, compared with 0.4 per 100,000 persons per year for those aged greater than or equal to 15 years. Reported by: P Figeroa, MBBS, O Nembhard, MBBS, Epidemiology Unit, Ministry of Health; A Coleman, MBBS, M Betton, MBBS, St. Ann Hospital, Jamaica. Health Studies Br, Div of Environmental Hazards and Health Effects, National Center for Environmental Health and Injury Control, CDC.

Editorial Note

Editorial Note: THS is characterized by acute onset of profuse vomiting, convulsions, coma, and sometimes death. Profound hypoglycemia (blood glucose levels as low as 3 mg/dL (1)) is observed in most cases. This problem is endemic in Jamaica, with 271 cases reported to the JMH since 1980.

An association between ackee poisoning and Jamaican vomiting sickness was first noted in 1875 and documented in 1904 (2). Ackee, the national fruit of Jamaica, is a food staple in many Jamaican diets. The ackee tree was imported from West Africa to Jamaica in 1778; ubiquitous in Jamaica, it is also found in the Antilles, Central America, and southern Florida (2). In Jamaica, fresh ackee are consumed directly following harvesting or can be obtained in markets when in season (December-March) (3). Canned ackee fruit is available throughout the year.

Unripe ackee contains hypoglycin A, a water-soluble liver toxin that induces hypoglycemia by inhibiting gluconeogenesis secondary to its limiting of cofactors (CoA and carnitine) essential for oxidation of long-chain fatty acids (1,4). Potential risk behaviors for ackee poisoning include 1) selection and cooking of unripe ackee; 2) purchase of tampered, forcibly opened ackee; and 3) reuse of the water in which unripe ackee has been cooked (3). Undernutrition is also thought to be associated with both susceptibility to and severity of THS, particularly among children in Jamaica (2).

In Jamaica, the epidemiology of ackee poisoning has not been well characterized, and the true incidence and mortality are believed to be underreported. In this investigation, retrospective case-finding of ackee poisoning using an explicit case definition identified 38 cases in the eight hospitals -- 32 more than had been reported to the JMH through routine surveillance for the same period. Because of this underreporting, determining whether an outbreak occurred or whether the eight cases of THS in the parish of St. Ann were associated with a specific event is not possible. In addition, because the medical officers in St. Ann had a special interest in THS, surveillance for this problem may have been heightened in the parish.

The JMH is reviewing the feasibility of introducing enhanced passive surveillance of THS. In addition, through public health inspectors, the JMH continues to monitor ackee fruit that is either sold fresh or canned. No cases of THS are known to have been reported among persons from the United States visiting Jamaica, nor have cases been reported in the United States.


  1. Tanaka K, Kean EA, Johnson B. Jamaican vomiting sickness. N Engl J Med 1976;295:461-7.

  2. Hill KR. The vomiting sickness of Jamaica: a review. West Indian Med J 1952;1:243-64.

  3. Ashcroft MT. Some noninfective diseases endemic in the West Indies. Trop Geogr Med 1978;30:5-21.

  4. Bressler R. The unripe ackee -- forbidden fruit. N Engl J Med 1976;295:500-1.

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