Seropositivity to Coxiella burnetii in primiparous and multiparous ewes from southern Australia: A cross-sectional study

Tom Clune,Amy Lockwood,Serina Hancock,Andrew N Thompson,Sue Beetson,Mieghan Bruce,Angus J Campbell,Elsa Glanville,Daniel Brookes,Colin Trengove,Ryan O’Handley,Caroline Jacobson

doi:10.1016/j.cimid.2021.101727

Abstract

The role of infectious diseases including coxiellosis in causing poorer reproductive performance of primiparous ewes are not well studied. The aims of this study were to determine if natural exposure to Coxiella burnetii is widespread in breeding ewes and whether seropositivity is associated with poor reproductive performance of primiparous ewes. Seropositivity to Coxiella burnetii was 0.08% (CI95% 0.01, 0.36) in primiparous ewes and 0.36% (CI95% 0.07, 1.14) in mature ewes. Coxiella burnetii was not detected in aborted or stillborn lambs using qPCR. These findings suggest C. burnetii infection was unlikely to be an important contributor to abortion and perinatal mortalities observed for primiparous ewe flocks, and exposure to C. burnetii was not widespread in ewes on farms located over wide geographical region of southern Australia. Whilst ewes on these farms were not an important reservoir for C. burnetii, sporadic zoonotic transmission from sheep is reported and has public health implications.

Highlights

The reproductive performance of primiparous ewes is often lower than that observed for multiparous ewes [1,2,3]
The aims of this study were to (i) determine if natural C. burnetii exposure is associated with poor reproductive performance of primipa rous ewes in southern Australia, (ii) determine if natural exposure to C. burnetii is widespread in primiparous and multiparous ewes, and (iii) determine if ewes represent an important reservoir for C. burnetii infection in humans
Foetal and lamb mortality between scan 1 and lamb marking for primiparous ewe lambs was 36% (1567/4351 foetuses identified at scan 1; range 14–71%) and for primiparous year lings was 29% (582/2103 foetuses identified at scan 1; range 20–53%)

Summary

Introduction

The reproductive performance of primiparous ewes is often lower than that observed for multiparous ewes [1,2,3]. Higher incidence of foetal or lamb mortality from pregnancy diagnosis to lamb marking has been reported for primiparous ewes compared to multiparous ewes [2,3,4]. A number of endemic diseases may cause abortion and poor viability of lambs in Australia [5,6]. It is not clear if infectious diseases are an important contributor to foetal and lamb mortality for primiparous ewes in Australia. Abortions are more likely to occur during gestation following primary infection, with no lasting impacts on reproduction in subsequent pregnancies [10,14]. Younger ewes that are immunologically naïve are at risk of abortion if infection occurs during pregnancy

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