Seroprevalence and risk factors for brucellosis in cattle and rodents in Kilosa district, Morogoro, Tanzania

Background: Brucellosis is a global zoonosis caused by gram-negative bacteria that affects a diverse array of hosts including humans, domestic animals as well as wild animals such as cattle (B. abortus), goats, and sheep (B. melitensis), pigs (B. suis), and rodents (B. neotomae), and results in financial setbacks in the livestock industry. This study aimed to identify risk factors and estimate the seroprevalence of brucellosis in cattle and rodents in Kilosa district, Tanzania. Methods: A cross-sectional study was conducted from January 2023 to March 2023, cattle were randomly selected and rodents were trapped using Sherman, wire cages, and havahart traps. Blood samples were collected from the jugular vein and heart of the cattle and rodents, respectively. Sera were harvested from the collected blood and stored at – 20 ºC. All the sera were screened for brucella antibodies using the Rose Bengal Plate Test (RBPT) and confirmed by competitive Enzyme Linked Immuno Sorbent Assay (c-ELISA). The risk factors were captured using a structured questionnaire and analyzed by computing the Chi-square test and generalized linear model. Results: The seroprevalence of brucellosis was found to be 5.31% in cattle (95% CI: 0.0286-0.089) and 0.72% in rodents (95% CI: 0.0002-0.0397). A significant association was observed between grazing style and brucellosis seropositivity in cattle, with cattle that grazed together with sheep and goats having significantly higher odds of seropositivity (OR=6.5; 95% CI: 1.74-42.17, **p < 0.01). Conclusion: The detection of Brucella antibodies in both species indicates ongoing transmission and potential risk to public health. Our findings suggest that rodents may serve as reservoirs of brucellosis, contributing to its persistence and spread. Further research is essential to characterize the specific brucella species circulating among cattle and rodents and to understand the dynamics of interspecies transmission

knowledge, attitude, and practice on brucellosis among livestock keepers in Kilosa district, Tanzania

Background: Brucellosis is a contagious bacterial zoonotic disease that is primarily caused by Brucella species. The current study aims to assess knowledge, attitude, and practice towards brucellosis among livestock keepers in Kilosa District-Tanzania.  Methods: The cross-sectional study design was employed from February to March 2023 in Kilosa district, Tanzania. A semi-structured questionnaire was employed to evaluate participants\u27 knowledge, attitudes, and practices related to brucellosis. Collected data were analyzed by using (Microsoft) MS Excel, and the chi-squared test. Results: A total of 150 randomly selected livestock keepers participated in the study, with the majority being male. Participants’ ages ranged from 20 to 70 years. While 138 out of 150 (92%) had heard about brucellosis, only 18 (12%) demonstrated good knowledge of its transmission between livestock and from livestock to humans. Most respondents (80%) were aware of the disease\u27s clinical signs, identifying abortion in animals and headaches in humans as primary symptoms. Regarding attitudes and practices, 52 (34.7%) strongly agreed that brucellosis is a serious disease in livestock, but only 20 (13%) considered it a significant health threat to humans. Alarmingly, 138 (92%) reported consuming unboiled raw or soured milk. A statistically significant difference was observed in knowledge levels based on sex and education, with a p-value (**p < 0.01) for each variable. These findings highlight gaps in knowledge and risky practices that may contribute to the spread of brucellosis among livestock and humans. Conclusion: This study has shown that there is little understanding and poor attitudes and practices towards brucellosis among livestock keepers in the Kilosa district. This can be addressed by providing community awareness campaigns about zoonotic diseases including brucellosis

Prevalence and molecular characterization of Bartonella species from rodents and their associated ectoparasites in Kilwa District, Lindi region, Tanzania

Background: Bartonella are facultative Intracellular gram-negative bacteria from the Bartonellaceae family. Several rodents associated with Bartonella species have been known to be transmitted by ectoparasites to animals and humans however, limited information is available about their epidemiology, host, vector, and species specificity, particularly in southern Tanzania. This study aimed to investigate the prevalence and molecular characterization of Bartonella species in rodents and their associated ectoparasites in Kilwa district, Southern part of Tanzania. Methods: A cross-sectional study was conducted to capture rodents using Sherman and Wire cage traps. Captured rodents were anesthetized using diethyl ether and dissected to extract spleen tissue. Ectoparasites were identified by examining their morphological features with a stereo microscope aided by ectoparasites identification keys. A total of 138 rodent spleen tissue and 93 pools of ectoparasites were subjected to conventional polymerase chain reaction (PCR) and sequencing targeting the gltA gene of Bartonella species. Results: The overall prevalence of Bartonella species in rodents was 3.62% with a statistically significant difference in prevalence among species (χ² = 12.951, df = 5, p < 0.01) compared to 3.23% in ectoparasites with no significant differences across species (p > 0.05). Bartonella infections were 3.37% in M. natalensis, 3.27% in R. rattus and 50.0% in G. dolichurus. The Laelaps species and Xenopsylla cheopis were found infected by 6.67% and 2.70%, respectively, while Rhipicephalus appendiculatus was not infected by Bartonella species. Sequence analysis of rodents and ectoparasites showed that the obtained sequences in the current study were genetically closely related to Bartonella mastoids from Turkey, Bartonella species from Kenya, and uncultured Bartonella species from South Africa (99.50–99.75% identity). Conclusion: The detection of Bartonella species in rodents and their associated ectoparasites implies the reservoir role of rodents and vectors in transmitting Bartonella species to humans and animals. The results suggest that further epidemiological studies need to be done to determine whether the identified Bartonella species could be responsible for animal and human cases of febrile illness in an area

A Study on the Ectoparasites and Hemoparasites Infections in Rodents from the Kilwa district, Tanzania

Background: Ectoparasites play a significant role in facilitating the transmission of disease pathogens and parasites that affect animals and humans. Purpose:  This study aims to assess the prevalence of ectoparasites and hemoparasites in rodents from the Kilwa district, Tanzania. Method: A cross-sectional study was conducted to trap 138 rodents using Sherman and wire cage traps. Ectoparasites were removed from rodents by using fine brushes and identified based on morphological features using a Stereo microscope with the assistance of dichotomous taxonomic keys. Blood samples were collected from supraorbital veins in captured rodents, and thick and thin smears were made, stained and examined using a Compound Microscope for screening hemoparasite. Results: The overall prevalence of ectoparasites in rodents was 57.87 % with a high infestation of rodents by Echinolaelaps (Laelaps) echidninus (44.20%) than Laelaps nuttalli (10.87%), Xenopsylla cheopis (12.32%), and Rhipicephalus appendiculatus (2.90%). Most ectoparasites were found in M. natalensis 76.40% followed by R. rattus 25.81%, and G. leucogaster 36.36%. Adult rodents recorded 63.41% of ectoparasites prevalence higher than juveniles 13.33% (p< 0.05). The overall prevalence of hemoparasites in rodents was 18.12%. The identified hemoparasites were Anaplasma sp. (13.04%), Babesia sp. (3.62%), and Trypanosoma sp. (1.45%) observed only in adult rodents. Conclusion: The study recommends engaging and encouraging the community to use integrated pest management practices for rodents and ectoparasite control and prevention to safeguard both human and animal health

Population dynamics of the Multimammate rat (Mastomys natalensis) and Makundi’s brush fur rat (Lophuromys makundii) and their implications in disease …

This research article was pulished by Springer,In 2024Understanding host population dynamics in connection to disease persistence is important for determining the epizootic risks present in plague foci. We used a capture-mark-recapture method to investigate the population dynamics of Mastomys natalensis and Lophuromys makundii in an active plague focus, in Mbulu District, Tanzania. We hypothesized higher abundance in plague-persistent locality and between habits and seasons. We found distinct patterns of abundance in M. natalensis between farm and forest habitats. The abundance was significantly higher in farms in plague persistent than non-plague persistent areas. The dry season showed a significant increase of abundance compared to the long rain season and the short rain season. A significant increase in breeding females was observed in farms in plague persistent than non-plague persistent localities while farms showed a significant decrease compared to forests. Dry season was associated with an increase in breeding females compared to the long rain season and the short rain season. Furthermore, the abundance of L. makundii showed a significant increase in forest in plague persistent than non-plague persistent localities. The abundance increased significantly during the dry season and long rain season compared to the short rain season. The proportion of breeding females was significantly higher in forests in plague persistent than non-plague persistent localities. The breeding females significantly increased during the dry and the short rain season than the long rain season. These findings contribute to our understanding of the ecological factors shaping the population dynamics of these species and their potential roles in plague persistence

Rodent abundance, diversity and community structure in a bubonic plague endemic area, northern Tanzania

A research article was submitted to journal MammaliaRodent-borne diseases such as bubonic plague remain a significant threat to public health in tropical countries. In plague-endemic areas, little information exists on the factors triggering periodic bursts, thus rendering preparedness strategies for preventing the negative impacts of the deadly zoonosis difficult. In this study, we assessed how species richness, diversity, and community structure of rodents are associated with plague persistence in Mbulu District, Tanzania. Rodent data were collected using the removal trapping technique. We captured 610 rodents belonging to 12 species, with Mastomys natalensis recording highest abundance. There was significantly higher abundance and species richness in persistent than non-persistent plague locality. Also, house premises recorded significantly lower species richness than farm and forest habitats. Additionally, we found three broad rodent community structures that varied significantly between studied habitat types suggesting high rodent populations interaction at fine-scale resource abundance. The high abundance and diversity of plague-susceptible rodent reservoirs suggestively contribute to the plague persistence in the foci. These results may be useful to developing preparedness strategies in these areas to control plague outbreaks

Mopeia Virus–related Arenavirus in Natal Multimammate Mice, Morogoro, Tanzania

A serosurvey involving 2,520 small mammals from Tanzania identified a hot spot of arenavirus circulation in Morogoro. Molecular screening detected a new arenavirus in Natal multimammate mice (Mastomys natalensis), Morogoro virus, related to Mopeia virus. Only a small percentage of mice carry Morogoro virus, although a large proportion shows specific antibodies

Density-dependent network structuring within and across wild animal systems

Theory predicts that high population density leads to more strongly connected spatial and social networks, but how local density drives individuals' positions within their networks is unclear. This gap reduces our ability to understand and predict density-dependent processes. Here we show that density drives greater network connectedness at the scale of individuals within wild animal populations. Across 36 datasets of spatial and social behaviour in >58,000 individual animals, spanning 30 species of fish, reptiles, birds, mammals and insects, 80% of systems exhibit strong positive relationships between local density and network centrality. However, >80% of relationships are nonlinear and 75% are shallower at higher values, indicating saturating trends that probably emerge as a result of demographic and behavioural processes that counteract density's effects. These are stronger and less saturating in spatial compared with social networks, as individuals become disproportionately spatially connected rather than socially connected at higher densities. Consequently, ecological processes that depend on spatial connections are probably more density dependent than those involving social interactions. These findings suggest fundamental scaling rules governing animal social dynamics, which could help to predict network structures in novel systems