DISCUSSION
This study provides crucial insights into the zoonotic transmission
cycle of leptospirosis in the Muheza District. The detection of
leptospirosis in both livestock and humans indicates that agricultural
and livestock practices contribute to the endemicity of the disease. The
high seroprevalence in rodents, particularly Rattus rattus ,
underscores their role as a significant reservoir, while cattle likely
act as incidental hosts, furthering the transmission to humans.
(Schoonman & Swai, 2009, 2010; Swai & Schoonman, 2012a; Motto et
al ., 2023;).
In the present study, the seroprevalence of antibody-specific
leptospiral antigens among humans, rodents, and cattle was examined by
using MAT as the reference serological method (Niloofa et al.,
2015). The overall seroprevalence in rodents, humans, and cattle was
5.97%, 13.13% and 12.5% respectively. The difference could be due to
the previous exposure to prophylactic use of antibiotics such as
amoxicillin and ampicillin to treat dry cough and the use of doxycycline
to treat stomach pain, explicitly patients attending hospitals within
the study locality which acts as an antibacterial lowering prevalence of
leptospirosis.
These findings revealed that the Rattus rattus is a potential
reservoir of leptospirosis in Muheza district, as evidenced by the high
infection rate among the rodents collected from various habitat types
within study sites. This can be attributed to the high population in the
area. But also, the fact that the species cohabits with humans and
cattle, as it is mostly found in houses and peri-domestic could be
another reason for being a potential reservoir of leptospirosis.
Comparison of the seroprevalence of Leptospira serovars among
rodent species showed statistical differences for habitat types and
locations. The current finding resembles other studies conducted
elsewhere in Tanzania, which also, unveiled the existence of leptospiral
antibodies in Rattus rattus ( Katakweba et al., 2012; Assenga et
al., 2015; Mgode et al., 2019; Motto et al., 2021; Mlowe et al.,
2023) . Moreover, in rodents, the predominant serovar was
Sokoine at 3.48% (n=7). The predominant of the serovar Sokoine in
rodents may be attributed to their potential role as a source of
leptospiral infection in humans and animals.
The variation in seroprevalence among different species and habitat
types highlights the need for targeted interventions based on ecological
and occupational factors. The finding that farmers are at the highest
risk reinforces the importance of occupational health measures, such as
protective clothing and improved hygiene practices, to reduce exposure.
(Nthiwa et al., 2019). This is in line with other previous
studies that have highlighted farmers as being the highest risk groups
for leptospirosis in parts of Tanzania and elsewhere (Schoonman & Swai,
2009; Hashemi et al ., 2021; Maze et al ., 2023). Other
researchers highlighted various groups including dog keepers (Msemwa et
al., 2021), livestock keepers (Motto et al., 2023), fishing
communities (Mgode et al., 2019), slaughter pigs (Ngugi et
al., 2019), slaughtered cattle (Swai & Schoonman, 2012b) as well as
miners and sewage workers (Hashemi et al., 2021) being the
highest risk group for contracting leptospirosis.
Interestingly, in humans, the predominant serovar was Grippotyphosa
followed by Sokoine. Other prevalent serovars included Hebdomadis,
Pomona, and Lora, with none detected in Canicola. The predominant of
Grippotyphosa in humans could be due to the high contact rate between
humans and cattle within the study locality, especially during the
milking stage. The predominance of Grippotyphosa in cattle may be due to
their role as maintenance hosts for this serovar. Cattle are recognized
as natural and maintenance hosts for serovar Grippotyphosa (Soareset al., 2020). (Assenga et al., 2015; Mgode et al .,
2021; Msemwa et al., 2021; Majawa et al., 2023; Mloweet al., 2023).
The study’s identification of co-agglutination between rodents, cattle,
and humans for multiple serovars further emphasizes the complex dynamics
of leptospirosis transmission in multi-host systems. The shared
environment, particularly water sources, likely plays a key role in
maintaining the infection cycle between these species. Mgode et
al ., 2021; Msemwa et al., 2021; Majawa et al., 2023).
The seroprevalence data for rodents, cattle, and humans in Muheza
District is consistent with other studies conducted in Tanzania, such as
in Katavi, where a high prevalence was reported in humans (29.96%), and
in Tanga, where bovine leptospirosis was also prevalent (Motto et
al ., 2023). These results underscore the importance of considering
local environmental and socio-economic factors when developing control
measures.