Prospective cohort study reveals unexpected aetiologies of livestock abortion in northern Tanzania

Abstract

Livestock abortion is an important cause of productivity losses worldwide and many infectious causes of abortion are zoonotic pathogens that impact on human health. Little is known about the relative importance of infectious causes of livestock abortion in Africa, including in subsistence farming communities that are critically dependent on livestock for food, income, and wellbeing. We conducted a prospective cohort study of livestock abortion, supported by cross-sectional serosurveillance, to determine aetiologies of livestock abortions in livestock in Tanzania. This approach generated several important findings including detection of a Rift Valley fever virus outbreak in cattle; high prevalence of C. burnetii infection in livestock; and the first report of Neospora caninum, Toxoplasma gondii, and pestiviruses associated with livestock abortion in Tanzania. Our approach provides a model for abortion surveillance in resource-limited settings. Our findings add substantially to current knowledge in sub-Saharan Africa, providing important evidence from which to prioritise disease interventions.

Economic Burden of Livestock Abortions in Northern Tanzania

“…The SEBI-TZ study was undertaken between October 2017 and September 2019 in 13 randomly selected wards in Arusha, Kilimanjaro and Manyara. Full details of sampling are described elsewhere (Thomas et al, 2021). Briefly, sensitization meetings were held with livestock owners in each ward within the study area.…”

“…Whilst noninfectious causes include genetics, nutrition, and other environmental factors, (NADIS, 2022), infections are thought to be a major cause of abortion (Mark L. Anderson, 2007), although determination of attribution to a specific pathogen is challenging and only occurs in approximately 20%-45% of cases (Anderson et al, 1990;Amouei et al, 2019;Campero et al, 2003;Derdour et al, 2017). Common pathogens that result in livestock abortions worldwide include Neospora caninum, Toxoplasma gondii, Chlamydia abortus, Coxiella burnetii, Brucella abortus, Rift Valley Fever Virus and Blue Tongue Disease Virus, (Akoko et al, 2021;Mohabati et al, 2021;Odendaal et al, 2020;Semango et al, 2019), with several of these pathogens also detected as the cause of livestock abortion in northern Tanzania (Thomas et al, 2021).…”