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.

An outbreak of Rift Valley fever among peri-urban dairy cattle in northern Tanzania

“…Samples were collected from 215 abortion events from November 2017 through October 2019. 9 Of the investigated abortions, 71 (33%) involved cattle, 100 (47%) goats and 44 (21%) sheep. Additional details on the breeds of affected animals are given in the supplementary materials .…”

“…This study and its principal findings are described in detail elsewhere. 9 Briefly, the study population included all livestock-keeping households in 13 wards in Arusha, Manyara and Kilimanjaro Regions. Livestock keepers in these regions have been classified as engaging in a mixture of agropastoral, pastoral and smallholder-based livelihoods.…”

“…A case of RVF-associated livestock abortion was defined as an abortion event with RVFV detected by one-step reverse transcription quantitative polymerase chain reaction (RT-qPCR) in any of the vaginal swab, foetal swab or placental tissues and evidence of RVFV antibodies by enzyme-linked immunosorbent assay (ELISA) on a blood sample collected on an acute or convalescent serum sample from the dam. 9 …”

“…RNA was extracted from swab, tissue and milk samples using a RNeasy Mini Kit (Qiagen, Hilden, Germany) as described by Thomas et al 9 Details on extraction from milk samples are given in the supplementary materials . Detection of RVFV by RT-qPCR on extracted RNA was performed using published protocols.…”

Leptospirosis outbreak in Tanzania: An alarming situation

“…This will be important in the early identification of leptospirosis cases for quick intervention to prevent adverse outcomes. To assess and comprehend leptospirosis case fatality and disease burden across the nation in highly susceptible communities and healthcare facilities, strategies to enhance surveillance and monitoring systems of infectious illnesses in people and animals are also crucial [ 18 ]. Leptospirosis can be prevented by proper use of personal protective equipment, such as protective eyewear, rubber boots and gloves, for those working in farming and livestock keeping activities, which are potentially high-risk environments for leptospirosis transmission [ 16 , 26 , 27 ].…”