Veterinary Medicine

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    Estimating the basic reproduction number for the 2015 Nyimba district bubonic plague outbreak.
    (The University of Zambia, 2018) Sichone, Joseph
    Plague is a re-emerging flea-borne infectious disease of global importance and in recent years Zambia has periodically experienced increased incidence of bubonic plague outbreaks. However, there are currently no studies in the country that provide a quantitative assessment of the ability of the disease to spread during these outbreaks. This limits our understanding of the epidemiology of the disease especially for planning and implementing quantifiable and cost-effective control measures. To fill this gap, the basic reproduction number, Ro, for bubonic plague was estimated in this study. Ro is the average number of secondary infections arising from a single infectious individual during their infectious period in an entirely susceptible population. It gives a quantitative measure of the transmissibility of an infectious disease in the population and it is used to estimate the expected magnitude and extent of spread for an infectious disease outbreak. More importantly, Ro is used to guide the magnitude of control measures that will be required to control the disease. Secondary epidemic data from the most recent 2015 Nyimba district bubonic plague outbreak in Zambia was analyzed. Ro was estimated as a function of the average epidemic doubling time based on the initial exponential growth rate of the outbreak and the average infectious period for bubonic plague. Ro was estimated to range between 1.5599 [95% CI: 1.382 - 1.7378] and 1.9332 [95% CI: 1.6366 - 2.2297], with average 1.7465 [95% CI: 1.5093 - 1.9838]. Further, an SIR deterministic mathematical model was derived for this infection and this estimated Ro to be about 1.4 to 1.5, which was within the range estimated above considering the 95% confidence interval. This estimated Ro for bubonic plague is an indication that each bubonic plague case can typically give rise to almost two new cases during these outbreaks. This Ro estimate can now be used to quantitatively analyze and develop measurable interventions against future plague outbreaks in Zambia. For example, based on the average Ro estimate in this study, a minimum mass treatment rate of about 43% would be enough to prevent the disease spread in such high risk populations in the country.
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    Detection of hatavirus in mice and the assessment of knowledge, attitudes and practices on hantavirus disease in mice consuming societies in eastern province, Zambia.
    (The University of Zambia, 2022) Chipinga, Jones
    Hantavirus is a zoonosis which can be rodent borne and recently the global scene has seen the expansion of its geographical distribution. Hantavirus disease is notifiable in America, Europe and Asia but it is underreported in Africa despite recent studies revealing the seroprevalence of Hantavirus both in humans and animals in Mozambique and Zambia respectively. Thus far, significant knowledge gaps remain and relatively little information is available for most rodent- borne Hantaviruses in Zambia. Therefore, we conducted a cross-section study to determine the presence of Hantaviruses in mice (n = 160) in Katete district Eastern of Province-Zambia. Using pan Hanta primers, Hantavirus was detected via RT PCR at a prevalence of 2.5% (4/160) (95% CI: 1.16-7.52) in Mastomys natalensis rodents collected from Katete district Eastern Province-Zambia. In parallel to laboratory analysis of samples, a cross-section survey using a semi-structured questionnaire (n = 160) was also carried out to capture information on knowledge, attitude and practices (KAP) regarding Hantavirus in mice consuming communities of Katete district Eastern Province. The average KAP score was calculated from total scores for knowledge, attitude, and practices and then assessed. The association between the level of knowledge and factors of knowledge, factors of attitude, and factors of practices was determined using Pearson chi-square. Multivariate analysis was used to determine the predictors of knowledge. Participants had an overall moderate knowledge (score = 59.57%), fair attitude (score = 51.40%), and good practices (score = 73.00%) towards Hantavirus. Only 48.72% (38/78) of participants had sufficient knowledge of Hantavirus. The study found that level of education (Secondary (OR: 0.69 (95% CI: 0.47–0.97)) (p = 0.047), not trapping mice (OR: 0.34 (95% CI: 0.16–0.82)) (p = 0.025), and consuming mice (OR: 6.05 (95% CI: 1.26–24.22)) (p = 0.034) were predictors of moderate knowledge on disease transmission from rodents. The current study reported that participants had moderate knowledge and fair attitude on top of displaying good practices towards reducing the transmission of diseases. Therefore, this study recommends community sensitization on Hantavirus and advocates for the importance of reporting suspected cases to relevant authorities for proper management
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    Antiviral potential of hadjod (Cissus quadrangularis) extract against newcastle disease virus.
    (The University of Zambia, 2023) Machamacha, Alberto Filipe
    Newcastle Disease (ND) is a highly contagious viral disease that has a devastating global impact on the poultry industry. Ethanol (EtOH) crude extract from the stem of Cissus quadrangularis (CQL) was prepared and tested against Newcastle Disease Virus (NDV) replication using an in- ovo assay in embryonic chickens. Cissus quadrangularis L, is a perennial plant of the Vitaceae family, with high in active ingredients that have been proved to act against a variety of diseases and disorders. The study aimed to evaluate the antiviral activity of crude extracts of C. quadrangularis against NDV. Nine-day-old embryonated chicken eggs were divided into ten groups (n=10) and received various treatments. Six groups were inoculated with Velogenic NDV (vNDV) isolate AF2 and used for testing antiviral efficacy. Five groups of ten (10) were treated with different concentrations of the working stock extracts solution. The phytochemicals such as alkaloids, tannins, saponins, flavonoids, phenols, steroids, and glycosides were revealed in stem crude extract in the phytochemical tests. Cytotoxicity studies, on the other hand, showed that embryonated eggs could tolerate the all-plant extract at concentrations of 100 mg/mL. Highest chick embryo mortality (73.7%) was observed in the control group (virus only) and lower (11%) in the high extract concentration (75 mg/mL). The tested extract exhibited in ovo antiviral activity against NDV, showing viral titre reduction at a range of 1:64 in the haemagglutination test, indicating 4-times viral load decline compared with untreated embryo (positive control; 1:512) The current findings have clearly demonstrated that the crude EtOH extract from stem of CQL has strong antiviral activity against NDV in ovo. The mortality was lower when the extract was applied and antiviral significant statistical efficacy was observed. In order to further validate the efficacy of the plant extract as anti-NDV, an in vivo study using live chickens and use of standard for fractionations to isolate individual constitutes are recommended. Keywords : Antiviral Activity, Newcastle disease, Crude extract, Cissus quadrangularis
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    Assessment of antibacterial properties of dried garlic and onion against common bacterial pathogens.
    (The University of Zambia, 2023) Kalyati, Constance
    According to the World Health Organization, the extensive and sometimes indiscriminate use of antibiotics for treatment and as growth promoters in the animal production industry has resulted in the widespread development of antibiotic resistance. As such, antimicrobial resistance cannot be overemphasized as the discovery trend of resistant strains has continued. Thus, the pursuit of new natural plant-based antibiotics is a call to action for scientists to save the world. Garlic and onions are traditional herbs that have been used since ancient times in the preparation of not only food but medicines as well. In this study, the aim was to assess if dried garlic, red, and yellow onions possess antibacterial properties and the effect evaporation procedures and temperatures used have on their activity. Cured Allium sativum (garlic) and Allium cepa (onion) were bought from the local market. The plants were dried, coarsely crushed, and macerated using solvents: ethyl acetate, ethanol, and water. To obtain the crude extracts, two evaporation procedures were used: water bath and oven evaporation; water bath evaporation was at a temperature of 95ºC, whereas oven evaporation was at 35ºC. To test for antibacterial activity, agar dilution method was used against standard American Type Culture Colony strains of Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Salmonella typhi all of which are of public health significance. The activity was then graded as susceptible, intermediate, or resistant. Among the extracting solvents used, water extracts had the highest yield potential, which was followed by ethanol and finally ethyl acetate in order of decreasing polarity. Results showed that extracts from the oven evaporating procedure were more efficacious compared to those of water bath evaporation procedure indicating that the active ingredient is heat labile to high temperatures and in this case 95ºC. The best antibacterial extracting solvent from the oven evaporating procedure was the water extracting solvent, which was effective against all four test organisms. The activity was followed by ethanol, with ethyl acetate being the least effective. Based on the water bath evaporating procedure, extracts obtained from ethanol were more efficacious compared to the two extracting solvents, which showed a higher percentage of bacteria resistance. Following the individual antibacterial assessment of garlic, red onion, and yellow onion with respect to the two evaporating procedures used, observations were made that the percentage of susceptible bacteria to the plant extracts subjected to oven evaporation was higher than the percentage susceptibility of the bacteria to the plant extracts subjected to water bath evaporation. Therefore, based on the findings, it can be said that dried garlic and onions do have antibacterial properties against bacterial pathogens under study and that the plants have a higher potency when exposed to a low evaporation temperature like 35ºC as opposed to a high temperature of 95ºC. However, evaporation at temperature 35ºC and below is recommended so as to minimize the exposure of these plants to heat, thereby raising their antibacterial activity.
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    Genomic epidemiology and zoonotic potential of staphyloccus aureus from pigs and humans in Lusaka province of Zambia.
    (The University of Zambia, 2023) Samutela, Mulemba Tillika
    Pigs have been shown to be a reservoir for Staphylococcus aureus (S. aureus) including methicillin resistant strains which are collectively called Livestock- associated S. aureus (LA-SA) and Livestock-associated Methicillin-resistant S. aureus (LA-MRSA), respectively. These strains significantly colonise and cause infection in farmworkers and other individuals in contact with pigs. These persons are presumably the source of LA-SA transmission to household members and their associates. However, there is sparse information about LA-SA strains circulating in most African countries, including Zambia. This study aimed at determining the genomic epidemiology and zoonotic potential of S. aureus from pigs, farm and abattoir workers in selected districts of Lusaka province of Zambia. It was a cross-sectional study in which a total of 493 pig nasal swabs, 53 hand and nasal swabs each were collected from farm and abattoir workers. Forty-four human clinical isolates from a previous study were also included for selected genotypic investigation. Conventional microbiological methods were used to detect and identify S. aureus while the disc diffusion method was used to determine the antimicrobial susceptibility patterns. Polymerase chain reaction (PCR) with gene specific primers was used to confirm the species identity of S. aureus and detection of antimicrobial resistance and virulence genes. Genetic diversity of the strains was done using spa typing and whole genome sequencing (WGS). The overall prevalence of S. aureus in the study was 33.1%, specifically 37.8% for pigs and 11.8% for humans. The isolates were resistant to several anti-staphylococcal antibiotics including penicillin, tetracycline, and ciprofloxacin, with resistance rates ranging from 18% to 98%. However, the isolates showed considerable susceptibility to chloramphenicol, gentamicin, and co- trimoxazole. All isolates were susceptible to vancomycin. Although the mecA and mecC genes which encode resistance to methicillin were not detected, other resistance genes encoding resistance to tetracyclines (tetM, tetK, and tetL) and to erythromycin (ermB and ermC) were detected using PCR, while WGS showed the presence of other resistance genes which encode resistance to beta-lactams (blaZ), macrolides (vga(A)V), and fluroquinolones (gryA and gyrlA). More virulence genes were detected in silico via WGS compared to using PCR. These virulence genes included the aureolysin gene (aur), hemolysin genes (hlgA, hlgB, and hlgC) and enterotoxin genes (seg, sei, sem, sen, seo and seu). Immune evasion cluster genes (sak and chp) were also detected in some of the isolates from pigs. While several serine like protease genes (splA to F) were detected in both human and pig isolates. Spa typing by both PCR and WGS revealed that most of the isolates belonged to the typical livestock- associated spa types (t1430 being the most common). Typical livestock-associated sequence types ST753 and ST9 were detected in two of the isolates. Novel spa and sequence types were detected among the isolates. Mobile genetic elements (plasmid, transposon and several insertion sequences) associated with the aforementioned resistance and virulence genes were also detected in silico in the isolates. Phylogenetic analysis based on WGS revealed that the isolates clustered together with typical livestock-associated ST398 MRSA isolates and were clonally related. The findings of our study show that LA-SA is present among pigs and workers who work closely with pigs in Zambia and there may be both zoonotic and anthropogenic transmission going on. Furthermore, these isolates pose a high risk to human health as they harbour both resistance and virulence genes which are possibly carried on mobile genetic elements and may thus spread easily. Therefore, continuous monitoring of S. aureus in this sector using a “One health” approach to combat S. aureus infections and prevention of the emergence and spread of antibiotic resistant strains is recommended.