The prevalence and risk factors for human Brucella species infection in a cross-sectional survey of a rural population in Punjab, India

Hannah R Holt,Manmeet Kaur,Javier Guitian,Satinder Bharti,Gagandeep Singh Grover,Vivek Sagar,Patrick Nguipdop-Djomo,Paviter Kaur,Isha Berry,Jasbir Bedi,Wendy Beauvais,Amit Kulashri,John Mcgiven,Punam Mangtani,Jatinder P Singh Gill,Rajesh Kumar

doi:10.1093/trstmh/trz133

Abstract

Brucellosis is an important neglected zoonosis. Effective cattle vaccines are available but are infrequently used in India, where rural households commonly own one or two cattle as sources of protein and income. We assessed the prevalence of infection and risk factors in humans. We conducted a cross-sectional sero-survey in randomly selected individuals in 60 villages in Punjab. Infection prevalence was assessed by positive Rose Bengal testing or immunoglobulin G enzyme-linked immunosorbent assay. Risk factors were adjusted for potential confounding using multivariable analyses. Of the 1927 subjects who were approached, 93% agreed to participate. Age-standardised prevalence for Brucella infection was 2.24% (95% confidence interval [CI] 1.61 to 3.11). More than 60% of households kept cattle and 10% assisted with calving or abortions. Nearly all individuals consumed boiled cow/buffalo milk from their own or neighbours' cattle and 3.3% consumed goat's milk. There was a 2.18 times increased odds (95% CI 0.96 to 4.95) of infection with calving/abortions and a 4.26 times increased odds (95% CI 1.33 to 13.6) with goat's milk but not bovine milk consumption. An association with calving/abortions and goat's milk consumption was seen. Brucella vaccination of household livestock would reduce the risk to humans in such settings. Additional measures include biosecurity training around calving/abortions, education to boil all milk and for healthcare workers to test for brucellosis.

Highlights

Brucellosis is a globally important zoonotic disease [1, 2] but not prioritized by international health-systems despite significant impacts on human and animal health. 1 The Gramnegative intracellular bacteria of the Brucella genus are endemic in livestock in low income settings, and transmitted to humans via direct contact with ruminants, or via raw dairy products 3
Brucellosis is often not recognised by health workers, and laboratory tests often unavailable [5, 6]
Of the 1801 individual serological samples tested, 41 had evidence of Brucella infection based on either Rose Bengal testing (RBT) and/or IgG positivity (11 by RBT alone, 23 by enzyme-linked immunosorbent assays (ELISA) alone, and 7 by both tests; a further 25 had inconclusive ELISA tests and were classified as seronegative for Brucella)

Summary

Introduction

Brucellosis is a globally important zoonotic disease [1, 2] but not prioritized by international health-systems despite significant impacts on human and animal health. 1 The Gramnegative intracellular bacteria of the Brucella genus are endemic in livestock in low income settings, and transmitted to humans via direct contact with ruminants, or via raw dairy products 3. Brucellosis is a globally important zoonotic disease [1, 2] but not prioritized by international health-systems despite significant impacts on human and animal health. In livestock Brucellae cause abortions and reduced milk yields 4. In humans they cause debilitating non-specific illness, including fever, fatigue, weight loss, headaches, and arthralgia persisting for months to years if untreated. Focal joint involvement such as sacroilitis causing disability is common 3. Brucellosis is often not recognised by health workers, and laboratory tests often unavailable [5, 6]. We assessed prevalence of infection and risk factors in humans

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Conclusion