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We detected West Nile virus (WNV) nucleic acid in crocodiles (Crocodylus niloticus) in Zambia. Phylogenetically, the virus belonged to lineage 1a, which is predominant in the Northern Hemisphere. These data provide evidence that WNV is circulating in crocodiles in Africa and increases the risk for animal and human transmission.

The study investigated the management practices that contribute to disease outbreaks in farmed tilapia in Lusaka and central and southern provinces in Zambia. It was a cross-sectional qualitative study undertaken from January to March 2021 in which questionnaires were administered to 49 farmers to assess their fish health management and biosecurity competence. Data were analysed using means, percentages, ratios, and logistical regression. The results showed that the majority of the farms had high stocking densities (>8 fish/m2, 44.4%), reared Nile tilapia (67.7%), and sourced water for farming from rivers and streams (45.7%). A few farmers measured water quality parameters daily (16.7%) and removed dead fish from ponds daily (20.8%). The stocking density (p = 0.013), fish species (p = 0.031), dead fish disposal methods (p = 0.023), and control of predator birds (p = 0.016) influenced the total mortality recorded on farms, while pond type (p = 0.031 and p = 0.045), water source (p = 0.023), and stocking density (p = 0.027) influenced the duration of a mortality episode. It is evident that some fish health management practices and biosecurity concepts among tilapia farmers in the study area are inadequate and may not contain disease outbreaks or the spread of pathogens.

The Coronavirus disease 2019 (COVID-19) pandemic has killed over two hundred thousand people by end of April, 2020. America and Europe top in deaths from COVID-19 whereas the numbers are lower in Africa for unclear reasons. Emerging evidence suggests the role of hyperactive immune responses characterised by high pro-inflammatory cytokines in severe cases of COVID-19 and deaths. In this perspective, we explore the possible factors that may contribute to mild inflammatory responses in some cases of COVID-19 by focusing on immune education, parasites, sex hormones and chronic diseases, as well as genetic tolerance. To build our perspective, evidence is also extracted from wild rodents due to their multi-tasking immune responses as a result of constant exposure to pathogens.

This study investigated disease outbreaks in farmed Oreochromis niloticus (Nile tilapia) in Siavonga among small-scale cage culture farms on Lake Kariba in order to establish bacterial etiological agents associated with fish mortality and to determine their antibiotic susceptibility. A total of 300 fish samples from 11 farms were aseptically collected and bacteria were isolated from the kidney, liver, brain, and spleen. The isolates were identified using their morphological characteristics and conventional biochemical tests. The antibiotic susceptibility of selected bacteria was determined by the Kirby–Bauer disc diffusion method. The following well-known fish pathogens were identified at a prevalence of Aeromonas spp. (13%), Pseudomonas spp. (10.3%), Micrococcus spp. (9.7%), Klebsiella spp. (8.7%), Lactococcus spp. (7.3%), Streptococcus spp. (7.0%), and Acinetobacter spp. (7.0%). All the isolates tested were susceptible to doxycycline, and complete resistance to ciprofloxacin, co-trimoxazole, and cephalothin was recorded in the Bacillus spp. The observed resistance could be attributed to bacteria from terrestrial sources as fish farmers do not administer antibiotics to fish. To our knowledge, this is the first study to establish the occurrence of several bacterial species infecting tilapia in Zambia and the first to determine the antibiotic susceptibility of fish bacteria among small-scale farms on Lake Kariba. The current study provides baseline information for future reference and fish disease management on Lake Kariba and in Zambia.

Infectious bursal disease (IBD) is an acute, highly contagious, and immunosuppressive viral disease of young chickens and remains one of the economically most important diseases threatening the poultry industry worldwide. In this study, 16 and 11 nucleotide sequences of the VP2 hypervariable region (VP2-HVR) and part of VP1, respectively, of IBD virus (IBDV) detected in vaccinated broiler chickens in Lusaka in 2012 were determined. Phylogenetic analysis revealed that these Zambian IBDVs separated into three genotypes of very virulent (VV) IBDVs. Although the majority of these viruses belonged to the African VV type (VV1), which consisted of viruses from West Africa, South Africa and Zambia, one virus belonged to the East African VV type (VV2). Interestingly, a Zambian IBDV belonging to the VV3 genotype (composed of viruses from several continents) clustered with attenuated vaccine strains. Although sequence analysis of VP2-HVR showed that all detected Zambian IBDVs had conserved putative virulence marker amino acids (i.e., 222A, 242I, 256I, 294I and 299S), one virus had two unique amino acid substitutions, N280S and E300A. This study demonstrates the diversity of Zambian IBDVs and documents for the first time the possible involvement of attenuated vaccine strains in the epidemiology of IBD in Zambia. Strict biosecurity of poultry farms, monitoring of live vaccine use in the field, surveillance and characterization of IBDV in poultry and development of a vaccine from local or regional IBDV field strains are recommended for improved IBD control in Zambia.

The capsaicin was extracted in-house from locally purchased chili pepper (Capsicum annum) using the conventional solvent extraction method. Varying concentrations of capsaicin were mixed with Lactococcus garvieae each and inoculated on Mueller Hinton agar to determine the minimum bactericidal concentration. Four groups of 100 fish each were injected with either 1) Capsaicin, 2) bacteria and capsaicin, 3) bacteria and 4) normal saline (negative control). The fish were observed for 7 days post treatment and experiment was repeated three times. Protection against infection was measured by the lack of clinical disease and survivability of the fish during period of experimentation. The minimum bactericidal concentration of capsaicin on growth of Lactococcus garvieae was 0.1967mg/ml. Significantly, more fish in the bacteria and capsaicin group survived (p<0.0001) compared to those injected with bacteria only. The findings suggest that chili pepper extract can prevent Lactococcus garvieae infection in tilapia. Competing Interest Statement The authors have declared no competing interest.

Antibiotic resistant Campylobacter spp causing campylobacteriosis continue to cause challenges in treatment of the infection. Poultry remains the main source of the foodborne disease. This study was undertaken to isolate and identify antibiotic resistant Campylobacter spp. A total of 160 cloacal swabs were taken from broilers at a poultry abattoir in Lusaka. The samples were analyzed using standard bacteriological test. Antimicrobial susceptibility test was conducted following Clinical and Laboratory Standard Institute guideline and three antibiotics were used ciprofloxacin, tetracycline and erythromycin. Results indicated that Campylobacter spp was isolated from 18.75% of the sample population, furthermore the isolates were resistant to erythromycin and tetracycline and susceptible to ciprofloxacin. The results highlight the growing concern of poultry being a source of multi-drug resistant pathogenic bacteria.

Aquaculture in Zambia is rapidly growing, contributing significantly to food security and income generation. However, the intensification of fish farming raises concerns about antimicrobial use (AMU) and the emergence of antimicrobial resistance (AMR). This study assessed the knowledge, attitudes, and practices (KAP) of fish farmers regarding AMU and AMR across 25 districts in Zambia’s ten provinces. Data were collected from fish farmers using a structured questionnaire distributed via district fisheries officers and analyzed through descriptive and inferential statistics, including logistic regression. The results revealed significant gaps in knowledge, with only 17.4% of farmers classified as knowledgeable about AMU and AMR. Attitude assessments showed that 60.5% exhibited positive attitudes toward responsible AMU practices, while the remaining 39.5% displayed negative perceptions. In terms of practices, 76.5% adhered to good practices, including consulting veterinary professionals and responsible antibiotic use, whereas 23.5% engaged in poor practices. Key factors influencing KAP outcomes included age, farming experience, and annual production capacity. Farmers aged 30–39 years and those with 1–5 years of experience demonstrated significantly more positive attitudes (p < 0.05), while those with higher production capacities (501–1000 kg) exhibited better practices (p < 0.001). The findings highlight critical knowledge gaps and inconsistent practices regarding AMU and AMR among Zambian fish farmers. Targeted interventions, including education programs, enhanced access to veterinary services, and strengthened regulatory frameworks, are essential to promote responsible AMU, mitigate AMR risks, and ensure the sustainability of aquaculture in Zambia.

This study aimed to determine the pathogenicity of bacteria (Aeromonas spp., Lactococcus garvieae, Acinetobacter spp., and Klebsiella spp.) isolated from Nile tilapia (Oreochromis niloticus) in small-scale aquaculture establishments on Lake Kariba through experimental infections. Healthy fish (50g ± 5g) were distributed among six transparent fish tanks labeled A to F. Fish in tanks A, B, C, and D were exposed to Aeromonas spp., Lactococcus garvieae, Acinetobacter spp., and Klebsiella spp., respectively, through intraperitoneal inoculation. Tank E received a co-infection of all isolates, while tank F served as the control group with an injection of normal saline. Clinical signs, mortalities and post-mortem lesions were recorded in all experimental groups, with histopathological examinations performed on liver, kidney, and spleen tissues. The findings indicate that Acinetobacter spp. and Klebsiella spp. exhibit low pathogenicity, evidenced by few clinical signs such as lethargy, pale skin, and fin erosion. The study further highlighted Aeromonas spp. and Lactococcus garvieae as the bacterial isolates causing significant clinical symptoms in Nile tilapia compared to Acinetobacter spp. and Klebsiella spp. following experimental infection. Co-infection with all bacterial pathogens demonstrated very high pathogenicity, with 100% mortality reported within seven days post-infection. The study proposes the development of a polyvalent vaccine to control fish disease outbreaks in small-scale aquaculture operations on Lake Kariba, thereby sustaining aquaculture production in Zambia.