Veterinary Medicine
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- ItemApplication of recombinant nucleocapsid protein-immunofluorescence assay (IFA) in hospital-based serological surveillance of rift valley fever in humans.(The University of Zambia, 2025) Mwansa, Peter ChibaleRift Valley fever (RVF) is a mosquito-borne viral zoonosis caused by the Rift Valley fever virus (RVFV), a negative-sense RNA virus belonging to the genus Phlebovirus in the family Phenuiviridae. Transmission to humans and animals occurs through mosquito bites (Culex and Aedes spp.), direct contact with infected animal blood or organs, ingestion of contaminated animal byproducts, or inhalation of aerosols from infected animals. In this study, analysis of human serum was conducted at the Virology Laboratory at the University of Zambia in Lusaka. Human serum samples were screened using a locally prepared recombinant Nucleocapsid-based Immunofluorescence Assay (IFA), where Vero E6 cells were transfected with a plasmid encoding the RVFV N gene and cultured on glass slides to express the recombinant protein. After incubation, the cells were fixed, preserved, and stored for later use. The commercial ID Screen® Rift Valley Fever Competition Multi-species enzyme-linked immunosorbent assay (ELISA) was used as confirmatory test; the tests were analysed according to the manufacturer’s guidelines. From previous studies a prevalence of 9.43% of RVF antibodies was recorded in Lusaka abattoir workers dealing with cattle, while in Mazabuka district 18.63% tested were sero-positive of RVFV antibodies. However, Zambia has not recorded an outbreak of RVF for over 30 years. The current sero-prevalence and risk factors associated with RVFV in human populations is not known. This study utilized convenience sampling, obtaining archived human serum samples from selected hospitals. Sample selection was based on availability, patient records, and storage conditions at -30°C. A total of 593 archived human serum samples were analysed, revealing an overall seroprevalence of 1.7% (10/593) on both IFA and ELISA. Lukulu District Hospital had the highest prevalence 0.84% (5/593); Choma General Hospital and Kanyama Hospital both had 0.34% (2/593), while Kalabo had the lowest 0.17% (1/593). Occupation was significantly associated with RVF seropositivity (p = 0.000), with farmers accounting for 1.35% (8/593) of cases. The highest seroprevalence was among farmers, individuals from Western Province, and patients attending Lukulu District Hospital. The aim of the study focused on the application of the Recombinant Nucleocapsid Protein (rNP) - IFA for hospital-based serological surveillance of RVFV in humans. IFA was successfully applied for the detection of RVF-specific antibodies in human serum samples, demonstrating high sensitivity and specificity in identifying seropositive cases. These findings highlight the potential of IFA as a valuable method for hospitalbased surveillance for further development of rapid, point-of-care diagnostic tests based on the recombinant RVFV Nucleocapsid protein (NP) could improve early detection in rural or resourcelimited areas.
- ItemGenetics diversity of theileria parva and muguga cocktail vaccine efficacy in cattle in Kabasha village in eastern Democratic Republic of Congo.(The University of Zambia, 2025) Simbuwa, MulongaEast Coast Fever (ECF), caused by the protozoan Theileria parva, is a major constraint to cattle health and productivity in Eastern, Central, and Southern Africa. In Eastern Democratic Republic of Congo (DRC), where the disease is endemic, control efforts are challenged by limited knowledge on the genetic diversity of circulating T. parva strains and their relationship to vaccine stocks. The Muguga Cocktail (MC), the most widely used live vaccine, may offer only partial protection in this region due to potential genetic divergence between local field strains and vaccine strains. This study was therefore conducted to characterize the genetic diversity and antigenic similarity of T. parva strains in Eastern DRC, to inform immunization strategies and guide effective deployment of the Infection and Treatment Method (ITM). The main objective was to determine the population structure and diversity of T. parva in vaccinated, unvaccinated, and sentinel cattle. Blood samples from Kabasha village were analysed using PCR targeting the Tp1 and Tp2 antigen coding genes. Sequences were aligned and compared with those of the Muguga Cocktail using phylogenetic trees, haplotype networks, and similarity scoring. Microsatellite and minisatellite genotyping covering six loci provided data on population structure assessed using allele diversity, Principal Component Analysis (PCA), and Fst statistics. The Tp1 gene was found to be relatively conserved. Out of 43 sequences analysed, 33 had 100% amino acid homology with the Muguga Cocktail epitope. Phylogenetic and haplotype analyses grouped most sequences closely with MC strains, indicating potential coverage by the current vaccine. In contrast, the Tp2 gene was highly polymorphic, with 235 of 258 epitopes being unique. These sequences formed distinct clusters, most of which were divergent from the vaccine strains. Microsatellite analysis revealed 91 unique alleles and 38 shared alleles among the three cattle groups. PCA showed partial clustering of field samples with MC stocks, while some samples formed distinct sub-populations. Fst values ranging from 0.096 to 0.119 indicated moderate genetic differentiation. These findings reveal the presence of multiple T. parva populations in Eastern DRC, some closely related to the Muguga Cocktail and others genetically distinct. The conserved nature of Tp1 epitopes suggests partial vaccine coverage, while the high diversity in Tp2 epitopes and microsatellite loci suggests the existence of local strains not fully protected by the current vaccine.
- ItemPhenotypic and molecular characterization of coagulase negative staphylococci from pigs and humans in Lusaka province, Zambia.(The University of Zambia, 2025) Chiyomba, LiswanisoCoagulase-negative staphylococci (CoNS) are normal inhabitants of human and animal skin as well as mucous membranes, yet they have emerged as significant pathogens in healthcare settings, causing serious infections. Initially described as avirulent in 1884, CoNS, particularly Staphylococcus epidermidis, are now recognized for their role in healthcare-associated infections contributing to 30-40% of nosocomial infections. Recent studies have highlighted the public health implications of CoNS as they can transfer antibiotic resistance genes and cause infections such as urinary tract infections, endocarditis and surgical site infections. While CoNS have been primarily studied in hospital environments, data from community settings, particularly in Africa, remain scarce. This gap in knowledge hinders a comprehensive understanding of the epidemiology and challenges associated with CoNS infections in the region. The objective of this study was to characterize CoNS isolated from pigs and humans working with pigs on selected farms in Lusaka Province using phenotypic and molecular techniques including the prevalence and resistance profiles of CoNS in Zambia. This was a cross-sectional study which involved archived CoNS isolates from pigs and humans working with pigs on selected farms in Lusaka Province. Species identification of the CoNS was done using traditional microbiological techniques such as culture and molecular methods like polymerase chain reaction (PCR). Antibiotic susceptibility testing was performed using the Kirby-Bauer disc diffusion method, while data was analyzed using SPSS version 28 (IBM Corp, Armonk, NY, USA). Common species identified were S. captis, S. warneri, S. xylosus, S. sciuri and S. caprae. The isolates were generally susceptible to antibiotics especially gentamycin (97%), chloramphenicol (96.3%) and ciprofloxacin (93.3%). Despite being susceptible, they also expressed a high prevalence of multidrug resistance at 60.7% to beta-lactams, tetracyclines, phenicols, sulfonamides, lincosamides and aminoglycosides. While, Methicillin Resistant-CoNS were prevalent when tested using phenotypic methods, none of the MR-CoNS tested positive for the mecA gene using PCR, suggesting other resistance mechanisms may be at work. These findings are significant to both animal and human health and suggest the importance of increased surveillance, antimicrobial stewardship (AMS) and research into resistance mechanisms of CoNS.
- ItemPrevalence and factors associated with malaria amongst under-five children in Senga hill district, Northern province Zambia.(The University of Zambia, 2025) Santu, Arthur ShabaMalaria is one of the major public health problems in developing countries like Zambia. Under-five years of age children are the most vulnerable group affected by malaria, accounting for 61% of all malaria deaths worldwide. Despite efforts to reduce the mortality and morbidity, the disease is still a prominent health problem in Senga Hill District. The District is described as a high risk area for malaria in the country. Knowledge of malaria prevalence and associated risk factors among under-five children in the district is insufficient. This study, therefore, was undertaken to assess the prevalence of malaria and associated risk factors amongst Under-Five Children in Senga Hill District, Northern Province, Zambia. Community-based cross-sectional study was conducted among under-five children in Senga Hill District from November 2022 to August, 2023. A structured questionnaire was used to collect data on hypothesised risk factors from the guardians or parents of children through face to face interview. A Care StartTM Malaria Rapid diagnostic test which can detect histidine-rich protein 2 of Plasmodium falciparum and Plasmodium lactate dehydrogenase of P. vivax was used to diagnose malaria. Bivariate analysis was used to determine associations between categorical variables, while for multivariable, binary logistic regression analysis was used to identify predictors of malaria among under-five children in the district. A total of 216 under-five children took part in the study. The overall prevalence of malaria was 31.9%. Correct use of ITNs (OR = 0.089, 95% CL = 0.034, 0.232, p = <0.001), those households that reported IRS had been done (OR = 0.375, 95% CL = 0.178, 0.789, p = 0.010) and those that reported having a single mosquito net (OR = 0.137, 95% CL = 0.141, 0.891, p = 0.003) had significantly reduced odds of underfive children being positive to malaria, than those that had not. Male children had significantly higher odds (OR = 3.035, 95%CL = 1.518, 6.068, p = 0.028) of being malaria positive than females. The local authorities and other concerned bodies should focus on the regular and proper use of ITNs and changing attitudes towards ITNs as malaria prevention and control measures.
- ItemDolutegravir-associated resistance gene mutations among people living with human immunodeficiency virus in Malawi.(The University of Zambia, 2024) Hussein, Felistus Zumazuma KanjiraThe emergence of drug resistance among Human Immunodeficiency Virus (HIV) patients poses a significant challenge to the success of antiretroviral therapy (ART) programs globally. In Malawi, where HIV prevalence remains a major public health concern, the incorporation of Dolutegravir (DTG) into first-line ART regimens has demonstrated significant promise in improving treatment outcomes. However, the development of resistance to DTG threatens these advancements, necessitating continuous monitoring and adjustments in treatment strategies. This retrospective study identified HIV drug resistance mutations associated with DTG use among individuals living with HIV in Malawi. Data from HIV-positive individuals aged 15 to 60 years, undergoing routine ART monitoring, were evaluated. Patients with high viral loads (≥ 1000 copies/ml) were included, and HIV-1 pol gene sequences were examined to identify mutations linked to DTG resistance. Phylogenetic analysis was performed to assess the relatedness of samples with resistance mutations. A total of 91 sequences from various districts in Malawi were reviewed, comprising 60.4% females and 39.6% males. DTG resistance mutations were found 15.4% of samples, with females accounting for 57.1% and males for 42.9% of those affected. G118R/R, G140A, Q148H/R, and R263K mutations associated DTG resistance, to varying levels, were identified. Among the 14 cases, 50% exhibited high-level resistance, 28% intermediate resistance, and 14.3% low resistance potential. The findings indicate a widespread distribution of DTG resistance mutations across Malawi, with evidence of both isolated and clustered patterns of resistance mutation from different districts emergence suggesting transmission of resistance within the communities. These DTG resistance mutations impact treatment outcomes by reducing the drug's binding efficiency to the integrase enzyme, which is essential for HIV replication inhibition. Mutations such as G118R and Q148H/R significantly impair DTG’s potency, potentially leading to treatment failure, virological rebound, and an increased risk of onward transmission of drug-resistant HIV strains. Additionally, these mutations can limit future ART options by conferring cross-resistance to other Integrase Strand Transfer Inhibitors (InSTIs), complicating treatment regimens and increasing healthcare costs.