Predominant Leptospiral Serogroups Circulating among Humans, Livestock and Wildlife in Katavi-Rukwa Ecosystem, Tanzania

Abstract

BackgroundLeptospirosis is a worldwide zoonotic disease and a serious, under-reported public health problem, particularly in rural areas of Tanzania. In the Katavi-Rukwa ecosystem, humans, livestock and wildlife live in close proximity, which exposes them to the risk of a number of zoonotic infectious diseases, including leptospirosis.Methodology/Principal FindingsA cross-sectional epidemiological study was carried out in the Katavi region, South-west Tanzania, to determine the seroprevalence of Leptospira spp in humans, domestic ruminants and wildlife. Blood samples were collected from humans (n = 267), cattle (n = 1,103), goats (n = 248), buffaloes (n = 38), zebra (n = 2), lions (n = 2), rodents (n = 207) and shrews (n = 11). Decanted sera were tested using the Microscopic Agglutination Test (MAT) for antibodies against six live serogroups belonging to the Leptospira spp, with a cutoff point of ≥ 1:160. The prevalence of leptospiral antibodies was 29.96% in humans, 30.37% in cattle, 8.47% in goats, 28.95% in buffaloes, 20.29% in rodents and 9.09% in shrews. Additionally, one of the two samples in lions was seropositive. A significant difference in the prevalence P<0.05 was observed between cattle and goats. No significant difference in prevalence was observed with respect to age and sex in humans or any of the sampled animal species. The most prevalent serogroups with antibodies of Leptospira spp were Sejroe, Hebdomadis, Grippotyphosa, Icterohaemorrhagie and Australis, which were detected in humans, cattle, goats and buffaloes; Sejroe and Grippotyphosa, which were detected in a lion; Australis, Icterohaemorrhagie and Grippotyphosa, which were detected in rodents; and Australis, which was detected in shrews. Antibodies to serogroup Ballum were detected only in humans.ConclusionsThe results of this study demonstrate that leptospiral antibodies are widely prevalent in humans, livestock and wildlife from the Katavi-Rukwa ecosystem. The disease poses a serious economic and public health threat in the study area. This epidemiological study provides information on circulating serogroups, which will be essential in designing intervention measures to reduce the risk of disease transmission.

Leptospira Seroprevalence Among Ugandan Slaughter Cattle: Comparison of Sero-Status With Renal Leptospira Infection

“…The microscopic agglutination test (MAT) was used to determine presence of anti-Leptospira antibodies; in accordance with the OIE standards (13). A panel of 11 serovars ( Table 1) representing 11 serogroups previously described as prevalent in Uganda (9) and those shown to be prevalent or maintained in cattle elsewhere in East Africa (14,15) was employed. Briefly, seven day old live Leptospira cultures were used to screen the serum samples at an initial dilution of 1:50.…”

Seroprevalence of canine leptospirosis, in Urban and Periurban, Morogoro, Tanzania

“…These findings are consistent with those of Moch et al (1975), who found seroprevalence of 8.3% in Ethiopia but differ from those of Mgode et al (2015) who reported 39% prevalence in dogs. A possible explanation to the findings by Mgode et al (2015) is that, all the reactors at titres 1: 20 were considered positive while in this study, only reactors with a titre 1:160 were considered positive (Cole et al, 1973;Assenga et al, 2015). According to Miller et al (2011), there is no consensus on cut off titre that constitutes seropositivity by MAT in leptospirosis.…”

“…Further doubling dilutions (1:20 to 1:160) were prepared in subsequent wells and then 50 μl of the fully-grown serovars in EMJH medium was added to the sera in the microtiter plate wells and mixed gently and then incubated at 30°C for 2 h. The serum antigen mixture was then visualized by DF microscopy for the presence of agglutination and the titres recorded. A sample was considered positive if 50% or more of the microorganisms in the microtiter well agglutinated at the titre 1:160 (Assenga et al, 2015). This was determined by comparing 50% of spirochaetes, which remained free with a control culture diluted 1:2 with PBS (Korver, 1992).…”

“…In Tanzania, early studies by Machang"u et al (1997) showed that 37% of dogs were seropositive to serogroup Icterohaemorrhagiae; this was higher than that of cattle, rodents and humans. Subsequent investigations provided further evidence of seroprevalence in African giant rats (Machang"u et al, 2004), pigs (Kessy et al, 2010) and cattle (Assenga et al, 2015). The reported seroprevalence data exhibits widespread exposure to Leptospira species in humans and animals in Tanzania, with dogs ranking highest, however, no clear link to the clinical disease in dogs has been established.…”

Rotavirus Burden, Genetic Diversity and Impact of Vaccine in Children under Five in Tanzania

“…Therefore, understanding the zoonotic potential of livestock RVA is of particular interest in Tanzania as, currently, the potential sharing of RVA genotypes between humans and animals remains unknown. In the rural areas of developing countries, including Tanzania, people live in close proximity to animals and sanitation, and hygiene may be poor, thus increasing the risk of zoonotic rotavirus infection [68]. Infected animals or humans shed over 10 billion infectious rotavirus particles per gram/milliliter stool [69], thus contaminating environmental objects.…”