Zoonotic risks for human leptospirosis in Kaski District, Nepal

Leptospirosis is predominantly an occupational disease in humans, with animals representing the major sources of infection. While leptospirosis is a recognised problem in Nepal, very little information currently exists about the extent of this disease in Nepalese human and animal populations.

Twenty four serovars of Leptospira have been described and attributed to animal reservoirs in Nepal, but the extent to which each serovar contributes to the human leptospirosis disease burden in the country is unknown.

View preliminary results.

Aims

This study aims to evaluate the major mammalian and environmental sources of infection for people by determining the distribution of Leptospira serovars in people and animals in Kaski district Nepal, where the disease is known to occur regularly.

Study design

This project consists of two studies that are being conducted simultaneously.

  • A prospective case-control study of hospital patients with (cases) and without leptospirosis (controls).
  • A cross-sectional study of Leptospira serovars in livestock, pets, and rodents in households of human patients with febrile illness, and an assessment of the risk factors for human infection.

Intended outcomes

  • Baseline information on the seroprevalence of leptospirosis in febrile human patients and their sympatric animals, which will inform the development of a national leptospirosis control program.
  • Establishment of a serum bank which can provide information on the occurrence of other endemic diseases of national importance.

Sampling methods

Blood samples will be collected from 412 patients presenting with acute febrile illness to hospitals or Primary Health Care Centres (PHC) in Kaski district.

Three to ten weeks after initial presentation, a household visit will be conducted in order to collect repeat blood samples from the human patients. During this visit a questionnaire survey will be conducted, and blood samples will be obtained from the family's domestic animals and from rodents that have been trapped in the house.

Laboratory methods

All blood samples will be sent to the Department of Immunology, Mahidol University, Thailand, to be tested using the Microscopic Agglutination (MAT) serological test. The initial 100–200 human samples will be tested for the full 24 serovars, the remaining samples will be tested using a panel of the 12 most frequently occurring serovars.