Abstract:
Leptospirosis is an emerging zoonotic infectious disease which affects humans and
animals worldwide as it causes febrile illness in humans. The disease has been reported in
a number of human-livestock-wildlife interfaces of Northern and Eastern Tanzania. Very
little is known of many zoonotic disease conditions in the research naive areas of Western
and Southern Tanzania. This study aimed at detecting the prevalence of Leptospira species
among agro-pastoralists at the human-animal interface areas of Katavi-Rukwa ecosystem.
Microscopic agglutination test (MAT) was used to detect antibody against six Leptospira
antigens including local serogroups Icterohaemorrhagiae, Ballum, Grippotyphosa, Sejroe
and reference serogroups Hebdomadis and Lora. Samples with MAT titers ≥ 1:160 were
scored as positive while MAT titers between 1:20 and 1:80 were scored as exposed to
Leptospira and absence of agglutination titers was scored as negative. Of the 267 samples
tested 80 (30%) were positive, 57 (21.3%) were negative and 130 (4 8.6%) were exposed
to leptospiral infection. Infection rate in adults was higher 51 (63.75%) compared to
children 29 (36.25%), P<0.05. Circulating serogroups were; Hardjo (15.7%);
Icterohaemorrhagiae (8.98%), Grippotyphosa (4.87%), Hebdomadis (3.37%), Australis
(1.49%) and Ballum (1.12%). Samples that were positive or scored as exposed by MAT
were further tested using polymerase chain reaction (PCR) targeting 16S ribosomal gene.
Pathogenic Leptospira was detected in 33 (15.5%) out of 212 while no saprophytic
Leptospira species was detected. Sequencing alignment based on 16S ribosomal gene
suggested Leptospira interrogans, kirshinei and uncultured Leptospira clone species as
circulating species among agro-pastoralists of Katavi-Rukwa ecosystem. These findings
suggest that in the Katavi leptospirosis in man is likely acquired from environment,
probably by indirect contact with contaminated water or soil. This study also revealed that
serological diagnosis of leptospirosis should be considered in the diagnosis on non-
malarial febrile illness in agro-pastoralists living in Katavi-Rukwa ecosystem, Tanzania.
