The prevalence of serum antibodies to Ehrlichia ruminantium infection in ranch cattle in Tanzania : a cross-sectional study

Abstract

Serum samples collected in a cross-sectional survey of grazing cattle on Manyara Ranch, Monduli district, Tanzania, were tested by indirect major antigenic protein 1 fragment B (MAP 1-B) ELISA to determine the seroprevalence of Ehrlichia ruminantium and to assess ranch-level risk factors for heartwater. Heartwater-exposed cattle were widespread on the ranch and overall seroprevalence was 50.3 % (95% CI, 44.9 -55.6), enough to indicate an endemically unstable situation. Multivariate logistic regression modelling was used to identify risk factors associated with seropositivity. Two factors appeared to increase the herd's risk for contracting heartwater. Seroprevalence increased significantly with age (β= 0.19 per year of age, P < 0.001) and animals carrying ticks of any species were associated with an increased risk of infection with E. ruminantium (Odds ratio, OR = 3.3, P < 0.001). The force of infection based on the age seroprevalence profile was estimated at 18 per 100 cattle year-risk. The current tick control measures on the ranch were associated with a decreased risk of infection with E.ruminantium (OR=0.25 for no dipping and OR=0.31 for low dipping, P < 0.001). Six tick species were identified; in order of frequency these were: Ambylomma variegatum 59.9 %, Rhipicephalus evertsi evertsi 13.9 %, Rhipicephalus pulchellus 12.5 %, Hyalomma truncatum 7.03 % and Rhipicephalus appendiculatus 6.07 %. The least encountered tick was Rhipicephalus simus, which accounted for 0.38 %. The cattle seemed well adapted to their environment and capable of resisting the tick burden under this extensive wildlife / livestock grazing and interaction system

Tick-Borne Rickettsioses, Neglected Emerging Diseases in Rural Senegal

“…Seven different tick species of 33 known in Senegal were collected in the studied regions. The most abundant species, Rhipicephalus evertsi evertsi , is one of the most common ticks that feed not only on domestic animals, but also many species of wild animals in Africa [41], [55]. The species is confined to the Afrotropical zoogeographical region in sub-Saharan Africa [44].…”

Prevalence and risk factors associated with Ehrlichia infections in smallholder dairy cattle in Nairobi City County, Kenya

“…This wide variability may suggest differences in factors related to cattle management across various areas. The prevalence recorded in the present study is sufficiently high; however, to warrant the implementation of appropriate control strategies since there may be a risk of clinical disease if susceptible animals are present [29]. The herd prevalence was 35.5%, at nearly twice the animal prevalence, possibly indicating that E. ruminantium infection in this area represents a herd health concern rather than an individual animal’s problem [29].…”

“…The overall prevalence of E. ruminantium in cattle reported in this study was 18.6%, similar to the 15% reported in Mozambique [27], though lower than 50% reported by Swai et al . [29] in Tanzania and 33% in Zimbabwe [26] and higher than 4.5% in Uganda [21] and 4.1% in Ethiopia [25]. This wide variability may suggest differences in factors related to cattle management across various areas.…”

Serological evidence of exposure to some zoonotic microorganisms in cattle and humans with occupational exposure to livestock in Antioquia, Colombia

“…In addition, mechanical transmission has been reported through fomites contaminated with infected blood 29 On the other hand, there is currently little evidence recording the circulation of the Ehrlichia species related to cattle or to the livestock context in Colombia, which contrasts with the exposure to Ehrlichia genus found in this study. However, literature reports exposure to Ehrlichia ruminantium in bovines from cattle systems in Tanzania 31 and molecular detection of this microbial agent in cattle systems in Turkey 32 . In Colombia, Ehrlichia species has been detected in hosts such as dogs, and Ehrlichia canis infection has been identified as the cause canine monocytic ehrlichiosis 33 ; also, its relation to infections in human cases has been suggested.…”