Leptospirosis in Barbados - abstract

ABSTRACT

Leptospirosis was first documented in Barbados by Bayley in 1939. Since that time it has continued to be a major cause of jaundice on the island, accounting for approximately fifty percent of the cases admitted to the medical wards. In 1979, the Government of Barbados in collaboration with the Medical Research Council (MRC) of the UK set up a laboratory for the diagnosis and study of the disease. In serological surveys carried out on the Island, Everald showed that 18.5 percent of 529 individuals tested from urban and rural areas had significant titres indicating previous exposure. Likewise, in a survey of school childern, he showed that 7.6 percent of 538 samples tested had significant titres. The majority of cases were exposed to the serovar Autumnalis. Autumnalis bim was first isolated by Jones from a stray dog in Bridgetown. It has subsequently been shown that bim is the most frequent cause of severe disease in man in Barbados. Two hundred and seventy-six hospital cases of leptospirosis have been confirmed since the inception of the laboratory in late 1979 to the end of December 1987. The cases seen in hospital have varied from 25 to 57 in any one year. On average, 15 cases per 100,000 population are admitted each year. The overall mortality rate has been 14.1 percent; however, since the inception of clinical research studies and aggressive supportive care in 1983 the mortality rate has been reduced to 9.4 percent. In 1981, a retrospective study of the incidence of thrombocytopenia in leptospirosis confirmed our published retrospective study showing that 30 of 49 (61.2 percent) patients had a platelet count of 100,000 or less. The association of thrombocytopenia and renal failure was also confirmed. In a study of twenty-four patients at the end of the first year of our MRC/UK-sponsored research programme, thrombocytopenia was demonstrated in 14 of these pateints. The only additional laboratory evidence suggestive of a disseminated intravascular coagulation lay in a mild elevation of the fibrinogen degradaton products, but this occurred with equal frequency in the non-thrombocytopenic patients. There was thus no casual relationship between the DIC and thrombocytopenia of leptospirosis. A randomized control study of high dose intravenous pencillin in icteric leptospirosis was conducted over a three-year period ending in December 1986. Thirty-eight patients were randomised to antibiotic therapy and forty-one to recieve intravenous fluids only. The two groups showed no significant difference in the time to defervence, return of biochemical parameters to normal, incidence of iritis or mortality in the two groups. Three patients (7.3 percent) died in the control group and one (2.6 percent) in the treatment group. The overall mortality for the study was 5.9 percent. Leptospires were recovered from urine cultures in six patients from the control gorup and none in the antibiotic group. It was concluded that while intravenous penicillin may sterilise the urine, it had little effect on the overall clinical outcome of jaundiced patients with leptospirosis. Twenty-four percent of patients had a cardiac arrhythmia, pericarditis or mycarditis when monitored by electrocardiagrams, halter monitor and echocardiagrams. Studies on the high incidence of hyperamylasemia (65 percent) in our leptospirosis patients are now in progress. The laboratory is continuing studies on the early diagnosis of the disease, looking at the application of common and specific DNA sequences from serovars of Leptospira interrogans for the diagnosis and distribution of leptospirosis, with the help of a new grant from the EEC (AU)