Original Research ARTICLE
The sero-epidemiology of Neospora caninum in cattle in northern Tanzania
- 1Nelson Mandela African Institution of Science and Technology, Tanzania
- 2Moredun Research Institute, United Kingdom
- 3School for Global Animal Health, College of Veterinary Medicine, Washington State University, United States
- 4Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, United Kingdom
- 5Centre for International Health, Department of Preventive and Social Medicine, Dunedin School of Medicine, University of Otago, New Zealand
- 6Ministry of Livestock and Fisheries Development, Tanzania
- 7University of Glasgow, United Kingdom
Neospora caninum is a protozoan intracellular parasite of animals with a global distribution. Dogs act as definitive hosts, with infection in cattle leading to reproductive losses. Neosporosis can be a major source of income loss for livestock keepers, but its impacts in sub-Saharan Africa are mostly unknown. This study aimed to estimate the seroprevalence and identify risk factors for N. caninum infection in cattle in northern Tanzania, and to link herd-level exposure to reproductive losses. Serum samples from 3015 cattle were collected from 380 households in 20 villages between February and December 2016. Questionnaire data were collected from 360 of these households. Household coordinates were used to extract satellite derived environmental data from open-access sources. Sera were tested for the presence of N. caninum antibodies using an indirect ELISA. Risk factors for individual-level seropositivity were identified with logistic regression using Bayesian model averaging (BMA). The relationship between herd-level seroprevalence and abortion rates was assessed using negative binomial regression. The seroprevalence of N. caninum exposure after adjustment for diagnostic test performance was 21.5% (95% Credibility Interval (CrI) 17.9 – 25.4). The most important predictors of seropositivity selected by BMA were age greater than 18 months (Odds ratio (OR) = 2.17, 95% CrI 1.45 – 3.26), the local cattle population density (OR = 0.69, 95% CrI 0.41 – 1.00), household use of restricted grazing (OR = 0.72, 95% CrI 0.25 – 1.16) and an increasing percentage cover of shrub or forest land in the environment surrounding a household (OR = 1.37, 1.00 – 2.14). There was a positive relationship between herd-level N. caninum seroprevalence and the reported within-herd abortion rate (Incidence Rate Ratio = 1.03, 95% CrI 1.00 – 1.06). Our findings suggest N. caninum is likely to be an important cause of abortion in cattle in Tanzania. Management practices, such as restricted grazing, are likely to reduce the risk of infection and suggest contamination of communal grazing areas may be important for transmission. Evidence for a relationship between livestock seropositivity and shrub and forest habitats raises questions about a potential role for wildlife in the epidemiology of N. caninum in Tanzania.
Keywords: Tanzania, Neospora caninum, Livestock husbandry, Prevalence, Risk factors, Reproductive losses
Received: 07 Jun 2019;
Accepted: 11 Sep 2019.
Copyright: © 2019 Semango, Hamilton, Kreppel, Katzer, Kibona, Lankester, Allen, Thomas, Claxton, Innes, Swai, Buza, Cleaveland and de Glanville. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Dr. William A. de Glanville, University of Glasgow, Glasgow, United Kingdom, email@example.com