A preliminary analysis of occupation and animal contact as risk factors for severe human leptospirosis in Barbados - abstract

ABSTRACT

Leptospirosis was confirmed in 242 of 433 (56 percent) febrile patients, aged 12 years and over, who were admitted to the Queen Elizabeth Hospital between November 1979 and December 1986; 133 (31 percent) of the patients had another cause of illness; 21 (5 percent) died before tests for leptospirosis could be completed; and 37 (8 percent) were positive for HBsAg. Questionnaires were completed for 199 of the 242 cases and 107 of the 133 with other febrile illnesses (controls). There was a higher proportion of males (74 percent) among cases than controls (57 percent), particularly young males. Compared to females in the 12-24 yr. age group, males aged 12-24 yrs. had a 261 chance of contracting leptospirosis and females in the 45-64 yr. age group had a 101 chance. Questions were asked, inter alia, about occupation and contact with animals. Non-manual indoor workers (considered to be a low-risk group) were given a value of 1.0, and the risks associated with other occupations were compared with them. The relative adjusted risks for cane or other agricultural workers (the largest group with 48 subjects), and labourers or other manual outdoor workers (the next largest with 35 subjects), were 13 and 116, respectively. These risks were statistically significant (p=<0.01) in the latter group, but of only borderline significance (0.05 < p > 0.10) in the agricultural workers. Patients who kept livestock had a 2.5 times greater risk of contracting leptospirosis than those who did not (p<0.001), but the increased risks associated with individual livestock species were not statistically significant in themselves. Higher proportions of cases than controls reported seeing rats, mice or wild animals, undertaking gardening or agricultural cultivation, digging ditches, clearing drains or walking barefoot outdoors, but none of these factors alone led to a statistically significant increase in the risk once allowance had been made for age, gender and sector (AU)