Veterinary Medicine
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- ItemPopulation genetic structure of ixodid ticks and phylogenetic analysis of rickettsia in Chongwe and Chisamba districts of Zambia.(The University of Zambia, 2024) Khumalo, Cynthia SiphoTicks are known vectors of various disease-causing pathogens worldwide. The distribution of ticks, their genetic makeup and relations has not been fully explored. This study focused on the population genetics of Ixodid ticks and the molecular epidemiology of Rickettsia species infecting them. Population genetics is vital to understanding the vectorial capacity of the ubiquitous Amblyomma, Hyalomma, and Rhipicephalus tick species that can transmit various disease-causing organisms including Rickettsia which cause a group of re-emerging diseases known as Rickettsioses. This study was conducted on ticks that were collected from Chongwe and Chisamba districts of Zambia in November 2020 and June 2021 respectively. Ticks collected were morphologically identified, homogenised, DNA extracted and polymerase chain reaction (PCR) run using primers to amplify the cytochrome subunit I (CO1), 12SrDNA and 16SmRNA for tick species verification and population genetics as well as ompA, ompB and gltA genes for Rickettsia molecular epidemiology followed by sequencing. Sequences obtained were blasted then edited using ATGC plug in Genetyx ver.12 and aligned using clustalw. For Rickettsia, phylogeny was established using Mega version XI. Comparison of population genetics was by MEGA XI, DnaSP, Arlequin (Fst), NETWORK and GENAlex (to measure diversity). It was found that tick populations in Chongwe and Chisamba district were identified as belonging to Amblyomma, Hyalomma and Rhipicephalus genus. These tick populations were high in genetic diversity and low in genetic differentiation. The tick populations were observed to carry Rickettsia species with Amblyomma and Hyalomma carrying over 95% of the Rickettsia detected. Rickettsia species detected were R. africae and R. aeschlimannii-like are both zoonotic known to cause febrile diseases of varying morbidities and mortalities. The study accounts for the low genetic differentiation to the free movement of animals that act as carriers for the ticks across the two districts. Due to this effective vector control methods can be extrapolated between the two districts. The high genetic diversity is an indication of an expanding population and hence potential occurrence of diseases carried by the ticks such as Rickettsia. The Rickettsia species detected are all zoonotic species and hence pose a risk of the outbreak of Rickettsioses in the areas the vectors are expanding to. This warrants surveillance of Rickettsioses and further research on vector populations, factors attributed to their expansion and the pathogens they carry around the country.
- ItemEscherichia coli contamination and risk exposure assessment of humans consuming water from unprotected wells in Chaona community, Mwachisompola area of Chibombo district of Zambia.(The University of Zambia, 2023) Zgambo, DorisA quantitative cross-sectional study was conducted to detect the presence of E. coli in unprotected water wells of Chaona community in Mwachisompola area, Chibombo District. A total of 48 wells drawn from four villages were sampled from the study area and an exposure assessment was done by use of add-in Model risk app in excel for risk assessment. The occurrence of the bacterium in well water was confirmed by laboratory processes of culturing, isolation and identification of E. coli. The identified E. coli was subjected to microbial resistance testing and the resistant genes were further detected by use of PCR. Out of 48 unprotected wells tested, 38 were indicative of E. coli presenting 79% (95% CI: 77.3 – 80.7%). The individual variation results that were positive to E. coli are Chilumbwa 5/38 (32%) (95% CI: 2.3 – 23.7%), Chabwa village 10/38 (26%) (95% CI: 12.1– 39.9%), Kafwilo 11/38 (29%) (95% CI: 14.6 – 43.4%) and Katobole12/38 (32%) (95% CI: 17.2 – 46.9%). Meanwhile, 16/48 (33.3%; CI: 31.4 – 35.2%) samples were found with an average number of CFU of between 1000 and 10,000 which was the highest range. E. coli isolates were also tested for Multi Drug Resistance (MDR) of which one isolate was indicative of being resistant to eight antibiotics and another to five antibiotics presenting (5.88%; CI: 3.2 – 8.6%) for each. Meanwhile, seven isolates were resistant to four antibiotics (41.2%; CI: 35.5 – 46.9%) and eight isolates were resistant to three antibiotics (41.1%) (CI: 35.4 – 46.9%). In addition, 30.9% (17/55) of the isolated E. coli organisms were found to be resistant to three or more classes of antibiotics primarily ampicillin, streptomycin, tetracycline, cefotaxime, nalidixic acid, norfloxacin and ciprofloxacin. The probability to be exposed to E. coli was revealed to be at 79.5% (95%; CI: 66.5 – 86.7%) when consuming water from unprotected wells in the study area. In conclusion, the study revealed that E. coli contamination was highly possible and it is recommended that water be boiled and or treated with chlorine before use at household level.
- ItemImpact of lockdown on COVID-19 transmission dynamics in Botswana : a mathematical modeling study.(The University of Zambia, 2024) Matokwane, Lebang JanetThe COVID-19 pandemic is the biggest public health and economic challenge the world has faced for the past three years. Since there was no vaccine during the early phase of the pandemic, Botswana imposed lockdown as one of the non-pharmaceutical interventions to mitigate the COVID-19 burden. Various mathematical models have been used in the current and previous epidemics for analysis of disease spread, forecasting and identifying trajectories as well as assessing effect of imposed mitigation strategies to aid policy makers in making informed decisions. In this study, a deterministic mathematical model was formulated to assess transmission dynamics of COVID-19 and impact of control measures undertaken in Botswana to deal with the pandemic. This study aimed at informing future decisions about lockdown by retrospectively examining its impact of implementation using a mathematical modeling approach. The proposed model was fitted to actual COVID-19 data obtained from the Ministry of Health and Wellness. Publicly available COVID-19 data for the period of 23rd June till 22nd September 2020 was used to validate the model. Model simulations were conducted to estimate the number of cumulative cases without intervention, with lockdown alone as well as in combination with contact tracing. Furthermore, the model was used to estimate the impact of lockdown on reproduction number. According to the model projections, 4362 cumulative confirmed cases would have been recorded after a year in the worst-case scenario of no interventions. After inclusion of interventions in the proposed model, model simulation results showed that lockdown yielded a significant reduction in number of cumulative confirmed cases by a range of 37.28% to 77.94%. In addition, a combination of lockdowns and contact tracing was also found effective in reducing number of cumulative cases by 42.62% to 70.99% (lockdown and medium contact tracing) and by 47.33% to 65.55% (lockdown and high contact tracing). Furthermore, difference in reproduction numbers were noted with a significant reduction noticed after enforcing of lockdown when the reproduction number dropped from 3.9 before lockdown down to 0.4 after full lockdown was implemented. Among all scenarios, lockdown measure was evaluated as the most effective control strategy. These study findings suggest that in the absence of vaccination, lockdown (especially full lockdown) can be used as a possible control measure to culminate SARS-CoV-2 transmission and effectively reduce number of cumulative cases in Botswana. Additionally, combination of intervention strategies; lockdown and contact tracing, alongside other NPIs, is likely to be the most robust means of controlling COVID-19 transmission and spread.
- ItemDevelopment of an in-house serological test to detect severe acute respiratory syndrome coronavirus-2 (SARS COV-2) using recombinant nucleocapsid protein.(The University of Zambia, 2024) Chiyumbabeenzu, MuubaCoronavirus disease-19 (COVID-19) is a major global concern for public health. This laboratorybased study was conducted at the University of Zambia, School of Veterinary Medicine (UNZAVet) laboratory. The study aimed at developing an in-house test to detect SARS-CoV-2 using the recombinant SARS-CoV-2 nucleocapsid gene. Recombinant based protein immunoassays are frequently used in veterinary medicine to detect antibodies against different viruses. There is no in-house recombinant protein-based immunoassay (IFA/ELISA) for detection of SARS-CoV-2 antibodies in Zambia. The N gene from the full SARS-CoV-gene was obtained by PCR using N gene primers tagged with SacI and SphI restriction ends. The N gene was cloned into a vector plasmid pCAGGS-MCS. The cloned N gene was transformed into competent DH5α cells. The N gene was purified and sequenced to ensure that there were no mutations within the gene and then transfected into VERO-E6 cells for protein expression. Archived serum samples (ten samples) of individuals previously infected with COVID-19 were tested for COVID-19 using OnSite® Rapid Test. The recombinant NP expressing cells were used as an antigen for an in-house immunofluorescent antibody test (IFA). The serum samples that tested positive on the rapid test were subjected to IFA using the recombinant N antigen prepared. None of the positive testing sera showed positive results on the assay. This could have been due to the expression system used which expressed a non-reactive protein. Another possible reason could have been the serum samples having low reactivity to the recombinant protein because the time frame between infection and when the samples were collected was not known. Hence, validation of this assay could not be conducted. The techniques used in recombinant antigen development, for detection of antibodies can potentially be applied in manufacturing of serological diagnostic kits. The findings of this study indicate that there is need for further investigations into the development of serological tests for sero-surveillance of COVID-19.
- ItemEffect of atmospheric temperature and rainfall on malaria incidence rates in selected districts of the three ecological zones of Zambia, over a seven- year period : retrospective study.(The University of Zambia, 2023) Silombe, MwenyaIn 2020, it was estimated that 241 million malaria cases were recorded globally, increasing from 227 million in 2019, with African countries contributing most to the increase. Studies have indicated that malaria is influenced by climate. Climate factors such as temperature and rainfall affect malaria incidences through changes in the mosquito life cycle and duration or parasite behavior such as fertilization and breeding of mosquito’s eggs. This study was conducted to determine the influence of atmospheric temperature and rainfall on confirmed malaria incidences in six selected districts of the three ecological zone of Zambia between the period of 2014 to 2020. Retrospective analytical comparative study design was used in this research. The first stage involved identifying the three ecological zones in Zambia; followed by randomly selecting two districts from each ecological zone. A total of six districts were selected and considered in the study. The second stage involved the collection of quantitative (secondary) data from the Ministry of Health and Meteorological Department both at district level. Confirmed malaria cases from 2014 to 2020 were used in this study. Microsoft® excel ® 2020 version was used to create graphs to show the annual trends of rainfall, atmospheric temperature and confirmed malaria incidences in six selected districts of the three ecological zones. Pearson’s correlation analysis was used to measure the relationship between annual atmospheric temperature, rainfall (independent variables) and confirmed malaria incidences (dependent variable). The results showed a low positive Pearson correlation of statistical significance between annual rainfall and confirmed malaria incidences in the three ecological zones of Zambia from 2014 to 2020 (r= 0.476, p < 0.001). This entails that; annual confirmed malaria incidences and rainfall had a direct relationship. The Pearson correlation between annual atmospheric temperature and confirmed malaria was low negative relationship but statistically significant (r= -0.451, p< 0.003). This entails that; an increase in the independent variable (temperature) leads to a decrease in the dependent variable (malaria incidences). Districts of the ecological zone 3 received the highest amount of rainfall and also recorded the highest number of confirmed malaria incidences. The districts of the ecological zone 1 recorded the highest annual atmospheric temperature but lowest numbers of confirmed malaria incidences. This study conclusively reports that there was a direct relationship between annual rainfall and confirmed malaria in the three ecological zones. Further, there was an inverse relationship (low negative correlation) between annual atmospheric temperature and confirmed malaria incidences but this relationship was statistically significant. Future studies should consider increasing number of sampling districts from each ecological zone.