Brucellosis in humans, livestock and rodents in Unguja, Zanzibar
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Date
2023-05
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Sokoine University of Agriculture
Abstract
Brucellosis is a globally significant zoonotic disease with profound
economic and public health implications. Brucellosis in humans is
characterized by intermittent fever. In Zanzibar, despite the decline
in malaria, fever cases persist in human population. However,
limited information exists regarding brucellosis in Unguja,
encompassing both humans and animals. A cross sectional study
was conducted at Unguja Island between July and November, 2022
to determine the seroprevalence of brucellosis in humans and
animals and assess knowledge, awareness, and community
practices related to its transmission and control. Prevalence of
human brucellosis was determined by analyzing 405 human serum
samples from three hospitals. Seroprevalence of animal brucellosis
was determined using 247 cattle, 130 goats, and 32 sheep serum
samples collected from farms across five districts, alongside 384
rodent serum samples from farms, households, and marketplaces in
seven districts of Unguja. The sera were screened using the Rose
Bengal Test (RBT), and confirmed by indirect ELISA (i-ELISA).
A structured questionnaire was used, on a purposively selected
population (n=236) based on willingness of participants and their
close association with keeping livestock in all seven districts of
Unguja who were residents for their knowledge, awareness and
practices related to occurrence and transmission of the disease. For
human brucellosis, 153 participants were assessed for their
knowledge, awareness and control measures towards the disease
by using the structured questionnaire. The study found a lower
prevalence of human brucellosis (0.74% n=3/405) based on iELISA.
Seroprevalence in cattle were 1.62% (n=4/247), goats (0%
n=0/130), sheep (12.5% n=4/32), and rodents (0.26% n=1/384).
From questionnaire survey, findings revealed that there is high
consumption of dairy milk (92.2% n=141) with relatively low (2%
n=3/153) raw milk consumption since most consume it boiled (82%
n=126). Few respondents were aware of human brucellosis (28.8%
n=44), and fewer identified it as a zoonosis (22.9% n=35).
For the animal brucellosis questionnaire, that had a total of 83 livestock
keepers, majority were male (75.9% n=63), farmers (50.6% n=42),
with secondary education (39% n=47) and an age range of 18-45
years (71.1% n=59). Cattle were the predominant livestock (41%
n=34), most animals (65.1% n=54) were reared under open housing
system and tethering (56.6% n=47); and family members (72.3%
n=60) primarily cared for the animals. The survey revealed that
awareness of brucellosis was evenly distributed, with 52% (n=43) of
respondents being unaware. Knowledge was primarily sourced from
mass media (40%) and veterinarians (32%). Clinical signs on
animals such as abortion (13% n=11) were observed. Veterinary
officers played a vital role in calving/kidding assistance (55.4%
n=46), and many respondents (60.2% n=50) reported using
protective gear when handling sick/calving animals. Reproductive
outcomes highlighted stillbirths (36.1% n=30) and abortions (33.7%
n=28), with placenta retention mostly in normal deliveries (32.5%
n=27) compared to abortions/stillbirths. Moreover, abortion took
place at different stages of pregnancy. Most animals were also not
vaccinated against brucellosis (90.4% n=75). This study concluded
that human and livestock brucellosis prevalence was low in Unguja
Island. Despite its rarity, the potential impact on animal productivity
and human heath underscores the need for persistent surveillance
and increased efforts in raising community awareness to interrupt
transmission and mitigate risks to livestock and public health.
Further research is also required to explore other potential causes of
fever in humans, abortion in livestock and the role of rodents in
disease occurrence and transmission.
Description
MSc Dissertation
Keywords
Brucellosis-humans, livestock, rodents, Unguja, Zanzibar