Case of clinical canine leptospirosis in Uganda

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

Despite evidence of both human and animal Leptospira exposures in Uganda, the epidemiology of the disease is still not well-investigated. Contact with animals and their environments have been pointed out as potential source of infection with Leptospira species in humans; and cattle may be an important reservoir in Uganda. In this cross-sectional study, we estimated the prevalence of anti-Leptospira antibodies by the standard microscopic agglutination test (MAT); and associated risk factors among slaughtered cattle. We also compared the performance of the MAT used in this study against a lipL32 based real time PCR (qPCR) assay previously conducted on the kidneys and urine of the same slaughter cattle as tested in this reported study. Of 500 cattle sampled, 27.8% (95% CI 23.9-32.0) tested positive (titer ≥ 100) to at least one Leptospira serovar, with the majority of seropositive cattle reacting to serovars Tarassovi (sg Tarassovi) (11.6%), Sejroe (Sg Sejroe) (7.8%), and Australis (Sg Australis) (5.2%). Older animals had 2.8 times (95% CI 1.0-8.2, p-value 0.055) greater odds of being seropositive than younger ones (<1.5 years). The sensitivity and specificity of the MAT over the qPCR were 65.9% (95% CI 50.1-79.5) and 75.9% (95% CI 71.7-79.7), respectively; with a negative predictive value of 95.8% and positive predictive value of 20.9%. In conclusion, slaughter cattle in this study were significantly exposed to pathogenic Leptospira species of mainly the Tarassovi, Sejroe, and Australis serogroups, with seroprevalence being higher among older cattle. The high specificity and negative predictive value of MAT as used in this study when compared to the qPCR assay may imply a rather strong association between seronegativity and absence of renal Leptospira infection. However, MAT predictability for renal Leptospira infection may be interpreted cautiously since predictive values of diagnostic tests are dependent on prevalence.

Bovine leptospirosis in abattoirs in Uganda: Molecular detection and risk of exposure among workers

Leptospirosis is a zoonotic bacterial disease reported worldwide. In Uganda, seropositivity has been reported in both humans and domesticated animals, including cattle. However, it remains unknown whether cattle are shedding leptospires and thus acting as potential source for human leptospirosis. We conducted this cross-sectional study in two cattle abattoirs in Kampala, Uganda between June and July 2017. Kidney and urine samples from 500 cattle sourced from across the country were analysed by real-time PCR to establish the prevalence of Leptospira-positive cattle and risk of exposure to abattoir workers. The species of infecting Leptospira was determined by amplification of secY gene and compared to reference sequences published in GenBank. Of 500 cattle tested, 36 (7.2%) had Leptospira DNA in their kidneys (carriers), 29 (5.8%) in their urine (shedders); with an overall prevalence (kidney and/or urine) of 8.8%. Leptospira borgpetersenii was confirmed as the infecting species in three cattle and Leptospira kirschneri in one animal. Male versus female cattle (OR = 3, p-value 0.003), exotic versus local breeds (OR = 21.3, p-value 0.002) or cattle from Western Uganda (OR = 4.4, p-value 0.001) and from regions across the border (OR = 3.3, p-value 0.032) versus from the central region were more likely to be Leptospira-positive. The daily risk of exposure of abattoir workers to ≥1 (kidney and/or urine) positive carcass ranged from 27% (95% credibility interval 18.6-52.3) to 100% (95% CI 91.0-100.0), with halal butchers and pluck inspectors being at highest risk. In conclusion, cattle slaughtered at abattoirs in Uganda carry and shed pathogenic Leptospira species; and this may pose occupation-related risk of exposure among workers in these abattoirs, with workers who handle larger numbers of animals being at higher risk.