Seroprevalence and molecular detection of toxoplasma gondii infection in rodents and pigs and risk factors for human exposure in Iringa municipality, Tanzania
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Date
2024-04
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Sokoine University of Agriculture
Abstract
Toxoplasma gondii is one of the protozoan parasites of worldwide
distribution causing infection to various warm-blooded animals. The
parasite's life cycle requires both primary and intermediate hosts.
Notably, rodents and pigs are significant intermediate hosts due to
their frequent contact with humans, thereby assuming a pivotal role
in the public health implications of the disease. Mortalities due to
Toxoplasmosis have been documented in southern highland regions
including the Iringa region. However, there is a lack of information on
the disease status in rodents and pigs and risk factors for human
transmission in the Iringa region. This study aimed at establishing
the seroprevalence and molecular detection of T. gondii infection in
rodents and pigs and risk factors associated with human exposure in
Iringa municipal in Tanzania. A cross-sectional study design was
adopted. The study wards were randomly for rodent sampling and
questionnaire survey. Blood samples were collected from both
rodents and pigs; in addition, brain samples were obtained from
rodents. The antibody ELISA technique was employed on rodent
and pig samples and seropositive samples were subsequently
subjected to molecular detection. The rodent brain samples were
also used in molecular analysis which is considered the most
susceptible part of infection for the parasite and pig blood samples
were used targeting the B1 gene at 530bp by nested PCR. Obtained
T. gondii DNA was further sent for sequencing. A total, of 127
rodents and 240 pigs were sampled, while the questionnaire survey
involved 143 participants who either reported complaints of rodent
infestation in their homes or kept pigs. The overall T. gondii infection
seroprevalence for rodents and pigs was 1.57% and 26.25%,
respectively. Seropositive rodents originated from Kitwiru ward,
seropositivity was predominantly associated with Mastomys
natalensis, while seropositive results were found across all surveyed
wards for pigs. The statistical analysis showed a significant
correlation between seropositivity and rodent species (df= 2,
χ2=6.2926, p=0.043). However, no significant correlation was found between seropositivity and sex in either rodents or pigs. T. gondii
DNA was detected from all two seropositive rodents and two out of
the sixty-three seropositive pigs. Sequences from this study formed
phylogenetic linkage when compared with other sequences from
different animals including humans from other parts of the globe with
the highest homology percentage of 99.15%. However, the
questionnaire survey showed an inadequate level of awareness of
about 30.1%, exposure to cat feces without gloves, keeping cats at
their homes, and mishandling of abortion cases in livestock were
identified as risk factors for disease transmission in humans in the
study area. Detection of antibodies against T. gondii infection in a
notable proportion of rodents and pigs, coupled with the subsequent
identification of its DNA within both animal species samples,
indicates the potential public health implications of these animals in
the study area. Moreover, the observed inadequate awareness
about toxoplasmosis amplifies the risk of disease transmission
among the community. Consequently, it is crucial to implement
effective strategies to safeguard the community from this neglected
but serious disease.
Description
MSc. Dissertation
Keywords
Toxoplasma gondii, Rodents, Pigs, Risk Factors