Charles N Edwards

Evaluation of the polymerase chain reaction for early diagnosis of leptospirosis

Early diagnosis of leptospirosis is important because severe leptospiral infection can run a fulminant course. The polymerase chain reaction (PCR) was evaluated for the detection of leptospires in clinical samples from patients with acute leptospiral infection. Blood and urine samples from 71 patients with leptospirosis were examined by PCR, culture or serology. Samples from 44 (62%) patients with the diagnosis of leptospirosis were positive by PCR as compared to 34 (48%) by culture. The presence of leptospires was demonstrated by PCR in 13 patients before the development of antibodies, as well as in two patients who were seronegative during their illness and at autopsy. Samples from 16 patients without leptospirosis were seronegative and culture negative, and also negative by PCR. We conclude that PCR is a rapid, sensitive and specific means of diagnosing leptospiral infection, especially during the first few days of the disease.

Leptospiral infection in school-children from Trinidad and Barbados

A serological survey for leptospiral agglutinins was undertaken between 1980 and 1983 in over 500 Barbadian and 500 Trinidadian school-children aged 7-14 years. The children were selected randomly from urban and rural schools, and examined three times at approximately annual intervals. A total of 12.5% of the Barbadian children and 9.5% of the Trinidadian children were seropositive at a titre of 50 using the microscopic agglutination test. On both islands, seroprevalence was higher in males than females, the difference being significant in rural schools. There was no evidence of a difference in prevalence between urban and rural schools, or between junior and secondary age-ranges. Analysis of the association of serology with socio-economic and behavioural factors showed a significant association in Trinidad with fathers occupation, but most other variables on both islands showed only weak non-significant associations. Fourteen children in Trinidad and three in Barbados seroconverted. Seroconversion in Trinidad occurred at a rate of 1.6% per annum and was significantly associated with livestock contact and with absence of a tapped water supply. In Trinidad, Autumnalis was the most commonly recorded serogroup, but this accounted for less than a quarter of seropositives. In Barbados, Panama accounted for over half the seropositives and was about four times more common than the next most common serogroup, Autumnalis. In Barbados, 39 persons aged 19 or less were hospitalized with leptospirosis between November 1979 and December 1986. Average annual incidence rates were 2.2, 4.9 and 13.3 per 100,000 in the 5-9, 10-14 and 15-19 age-groups, respectively.

Prevention and treatment of leptospirosis.

Leptospirosis is a common zoonosis acquired by exposure to body fluids, to tissues of infected animals, or to contaminated soil or fresh water. Large outbreaks of leptospirosis have occurred following excess rainfall or in tourists following exposure to fresh water during adventure activities. Prevention may be achieved through the use of protective clothing or by changes in animal husbandry. Immunization is not widely used in human populations but has a role in agriculture. Oral administration of doxycycline (Periostat® , CollaGenex) once-weekly can give short-term protection in high-risk environments. The disease in humans has a broad range of symptoms. Treatment may be symptomatic or may require administration of antibiotics, such as doxycycline or penicillin.

Severe primary HIV-1 infection among black persons in Barbados.

Descriptions of primary HIV-1 infection have so far been based on Caucasians living in industrialized nations. Due to studies of leptospirosis in the predominantly black population of Barbados, serum was available for patients admitted with acute febrile illnesses to the Queen Elizabeth Hospital (QEH). By searching the medical records of 510 adult patients with known HIV-1 infection we identified 10 patients who had stored serum from an admission for an acute febrile illness that predated or coincided with their first HIV-1-positive test. Serological testing confirmed primary HIV-1 infection in 9 and was suggestive in the 10th patient. The clinical features of these 10 patients were in keeping with previous descriptions of primary HIV-1 infection but differed from leptospirosis cases seen at the QEH. One patient died during his seroconversion illness and another died 3 months after seroconversion. The findings suggest that severe primary HIV-1 infection could be a relatively uncommon occurrence, that the condition may be misdiagnosed, and that cases may not occur until the AIDS epidemic is established.