Bernard Mudenda Hang’ombe

This study examines the performance of six dairy co-operatives in Namwala District, Zambia, over a decade (2014–2023) using a convergent mixed-methods design. Quantitative analysis employed descriptive statistics and OLS regression on a balanced panel of 40 co-operative-year observations, while qualitative insights were derived from five focus group discussions with 75 participants (25 female, 50 male). Membership grew from 412 to 2,000 (CAGR 19.2%), yet milk production exhibited marked volatility, ranging from 389,000 to 1,910,000 litres annually. Regression analysis reveals a significant negative relationship between membership and per-farmer productivity (β = −3.48, p < 0.001), indicating a dilution effect whereby membership expansion outpaces productive capacity. Milk price positively predicted total production (β = 14.48, p = 0.035), while the revenue model (adjusted R² = 0.941) confirms that production volume and price, not membership size, drive co-operative income. Focus group discussions identified drought, feed scarcity, governance instability, and inadequate veterinary services as principal constraints, while also documenting the emergence of informal milk trading networks as adaptive institutional responses. The study concludes that membership-driven scaling without parallel investment in productive capacity undermines individual farmer returns, and recommends productivity-first growth strategies, governance strengthening, climate-resilient infrastructure, and quality-based pricing to sustain co-operative performance.

Background and Aim: Non-typhoidal Salmonella remains a significant zoonotic pathogen with substantial implications for animal and public health, particularly in regions where domestic animals and wildlife share ecological interfaces. The invasion protein A (invA) gene is widely used as a molecular marker for detecting Salmonella; however, its sequence variability across host species in sub-Saharan Africa remains poorly understood. This study aimed to characterize nucleotide diversity and phylogenetic relationships of the invA gene among Salmonella isolates obtained from domestic animals and free-ranging wildlife in selected regions of Zambia. Materials and Methods: A total of 12 invA gene amplicons derived from previously confirmed Salmonella isolates from domestic animals (n = 10) and wildlife (n = 2) were selected for sequencing. Polymerase chain reaction products were purified and sequenced using BigDye terminator chemistry on a 3500 Genetic Analyzer. Sequence assembly and editing were performed using GENETYX software. Multiple sequence alignment was performed with ClustalW, and phylogenetic relationships were inferred using maximum-likelihood with the Tamura–Nei model in MEGA7. Comparative analysis included eight reference sequences retrieved from GenBank. Results: The invA gene sequences demonstrated high nucleotide similarity (98.0%–100.0%) among isolates from domestic animals and wildlife, while showing broader variability (74.0%–100.0%) when compared with global reference strains. Six distinct sequence types were identified, with the majority originating from chicken isolates. Nucleotide substitutions were predominantly observed between positions 40 bp and 250 bp, indicating a potential hotspot for genetic variation. Some substitutions resulted in amino acid changes, suggesting possible structural and functional implications for the invasion protein. Phylogenetic analysis revealed that all Zambian isolates clustered within a single major lineage (Clade A), indicating close genetic relatedness across host species. Conclusion: This study provides the first evidence of invA gene sequence polymorphism among Salmonella isolates from domestic animals and wildlife in Zambia. The findings highlight the dynamic evolution of Salmonella at the wildlife–livestock interface and underscore the importance of molecular surveillance in understanding zoonotic transmission. The identified sequence variations may have implications for diagnostic accuracy and the development of region-specific detection tools, reinforcing the need for continuous genomic monitoring under a One Health framework. Keywords: domestic animals, invA gene, molecular diversity, non-typhoidal Salmonella, phylogenetic analysis, wildlife interface, Zambia, zoonotic transmission.

Fish production is threatened by frequent disease outbreaks, especially bacterial diseases that cause significant economic losses. This study characterized the key virulence gene profiles of Aeromonas hydrophila and Lactococcus garvieae isolated from diseased Nile tilapia in southern Zambia and assessed genotype–lesion associations. A total of 163 clinically affected tilapia were examined, from which A. hydrophila (43%) and L. garvieae (22%) were recovered predominantly from brain and kidney tissues. Virulence gene screening showed that A. hydrophila exhibited low-frequency profiles dominated by hemolysin A (hlyA) (20.5% in broodstock) and elastase (ela) (11.5% in grow-out), while aerolysin (aerA) and enterotoxin (act) were infrequently detected. L. garvieae displayed a hemolysin-skewed profile, with hly2 being most prevalent (27.3% in broodstock; 21.4% in grow-out), hly2 detected only in broodstock, and capsule gene cluster (CGC) and fibronectin-binding protein (fbp) genes occurring rarely. Significant gene–lesion associations linked aerA and ela with pale gills (r = 0.41, p < 0.01; r = 0.24, p = 0.05, respectively), act with skin discoloration (r = 0.27, p =0.02), and demonstrated inverse correlations between hlyA and fins (r = −0.4, p < 0.001) or hepatic hemorrhages (r = −0.27, p = 0.02) in A. hydrophila. In L. garvieae, hly3 correlated with enlarged liver (r = 0.23, p < 0.001), corneal opacity (r = 0.15, p = 0.05), and gill necrosis (r = 0.21, p = 0.01), while hly2 and capsule genes were associated with skin discoloration (r = 0.18, p = 0.02; r = 0.24, p < 0.001, respectively). Overall, virulence determinants occurred at low frequencies and in limited combinations, suggesting the circulation of less virulent strains and underscoring the value of genotype-informed surveillance for improving disease control in tilapia aquaculture.

Background. Carbapenem and third-generation cephalosporin (3GC) resistance among Gram-negative bacteria poses a serious threat to human and animal health. This study aimed to identify and characterize carbapenem- and 3GC-resistant Enterobacterales isolated from poultry in Lusaka Province, Zambia. Methods. Ninety pooled cloacal samples were collected from market-ready broiler chickens in the Chongwe and Chilanga districts of Lusaka Province. The isolates were screened for 3GC and carbapenem resistance using the disc diffusion and broth microdilution methods. PCR and Sanger sequencing were performed for species identification and detection of β-lactamase-encoding ( bla ) genes, including bla _CTX-M , bla _TEM , bla _OXA-1 and bla _SHV . Hierarchical clustering was used to assess phenotypic and genotypic relationships. Results. A total of 83 3GC-resistant Gram-negative isolates were recovered, of which 12% were also carbapenem resistant. Escherichia coli was the most prevalent species, followed by Klebsiella pneumoniae and Enterobacter spp., then Pseudomonas aeruginosa, other Pseudomonas spp., Acinetobacter baumannii , Citrobacter freundii and Aeromonas caviae . Multidrug resistance occurred in 84.3% of the isolates, with the highest resistance to ampicillin, tetracycline and co-trimoxazole. Overall, 80.7% of the isolates harboured at least one of the four tested bla genes, with bla _CTX-M and bla _TEM being the most common. Hierarchical clustering revealed that isolates from both districts shared similar phenotypic and genotypic resistance patterns. Conclusions. The presence of multidrug- and carbapenem-resistant Enterobacterales from poultry highlights the emergence of carbapenem resistance in Zambia’s food production sector. The detection of imipenem-resistant isolates indicates the potential for transmission of resistance genes between animals and humans. These findings underscore the need for prudent antimicrobial use, strengthened stewardship and a One Health surveillance approach to contain the spread of carbapenem resistance genes.

Background/Objectives: The deposition of antibiotic residues in animal source foods has become a global public health threat. This study aimed to assess antibiotic class residues in raw cow milk from smallholder dairy farms in Mbala and Kasama, Zambia. Methods: A cross-sectional study was conducted, in which 93 milk samples (54 from Mbala and 39 from Kasama) were randomly collected from lactating cows on 56 farms between May and June, 2025. The samples were analyzed using the Charm II assay for beta-lactams, tetracyclines, macrolides, sulfonamides, and aminoglycosides. A total of 100 mL of milk was collected in sterile plain tubes, placed in a cooler box with ice packs, and transported to the district laboratory’s freezer and then delivered to the Central Veterinary Research Institute at (−18 to −20 °C), where they were stored at −20 °C. Statistical significance between districts was determined using Pearson’s chi-square, and associations between a district and the occurrence of antibiotic residues in milk were evaluated using logistic regression. Data were analyzed using Stata 14.2 at a 95% confidence level (p = 0.05). Results: A total of 91.4% (n = 85) of samples had antibiotic residues above EU/MRLs, with mean positive samples being 0.91 ± 0.28 and a significant association between a district and residue occurrence (OR = 0.086; p = 0.025). Approximately 44.1% of the samples had multiple antibiotic residues. Approximately 82.1% of samples from Kasama and 98.1% from Mbala had antibiotic residues (p = 0.006). Approximately 68.8% of samples had sulphonamides, and 58.1% macrolides, indicating their widespread use. Tetracyclines were 12.9%, beta-lactams 9.7%, and aminoglycosides 2.2%. Conclusions: A majority of milk samples had antibiotic residues above EU/MRLs, raising public health threats and necessitating the development and implementation of policies.

The capsaicin was extracted in-house from locally purchased chili pepper (Capsicum annum). Varying concentration of capsaicin was 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 protect tilapia against L. garvieae infection.

This study underscored the public health implications of antibiotic use in poultry pro-duction by evaluating antimicrobial susceptibility of ESBL-producing Escherichia coli isolated from intensively reared and free-range chickens in selected Zambian districts. A cross-sectional study analysed 112 faecal samples (56 from free-range and 56 from in-tensively reared chickens) collected from seven veterinary camps, of which five (5) were from Kabwe and two (2) from Kapiri Mposhi Districts. E. coli from the samples were cultured on MacConkey agar containing Cefotaxime, and analyzed by PCR for the presence of blaCTX-M, blaSHV, and blaTEM resistance genes. ESBL-producing E. coli were found in 11.61% of samples (5.35% free-range; 6.25% intensively reared). Overall, of the thirteen samples that yielded isolates resistant to the panel of antibiotics used, 58.9% of isolates showed resistance to β-lactams and other antibiotics. Chi-Square analysis at α=0.05, revealed no statistically significant difference in the carriage of Extended Beta Lactama-se-producing E. coli between intensively reared and free-range chickens. Both intensively reared and free-range chickens in Zambia harbour ESBL-producing E. coli, indicating widespread antimicrobial resistance. The absence of a statistically significant difference in ESBL producing E. coli between intensive and free-range production systems indicates that free-range birds are comparably exposed to antimicrobial-resistant pathogens. This demonstrates an urgent need to reinforce antimicrobial stewardship, implement surveillance strategies, and promote responsible antibiotic use across poultry production systems.

Cage aquaculture in Lake Kariba, Zambia, is critical to the region’s fish production but faces significant challenges in disease outbreaks. This study assessed the Knowledge, Attitudes, and Practices (KAP) of aquaculture producers in Siavonga concerning fish health and disease risk management. Data were collected through structured interviews with 14 producers, representing small, medium, and large-scale farms. The study aimed to identify gaps in biosecurity awareness and practices, particularly in relation to disease prevention and control. The results showed that knowledge of biosecurity and disease risks was predominantly low across all farm scales. Specifically, 90% of small-scale producers and 100% of medium-scale producers exhibited low knowledge, while 50% of large-scale producers showed low knowledge. Attitudes toward biosecurity were generally negative, with 90% of small-scale producers holding negative attitudes, compared to 50% of large-scale producers who demonstrated positive attitudes. The implementation of disease management practices was more consistent in medium- and large-scale operations, with 100% of large-scale farms following moderate to good practices, compared to 100% poor practices in small-scale farms. Significant gaps in adherence to best biosecurity practices were observed, particularly in small-scale farms. For instance, 60% of small-scale farms did not follow quarantine procedures, and only 20% assessed disease risks pre-movement. In contrast, 100% of large-scale farms implemented quarantine measures and assessed disease risks before moving fish. This study highlights the need for targeted interventions to improve biosecurity knowledge and practices, especially among small-scale producers, who constitute 71.4% of the respondents. Training, resource allocation, and policy enforcement are crucial to addressing these gaps and mitigating the risk of disease outbreaks that threaten the aquaculture sector’s sustainability in Lake Kariba.

The authors wish to make the following correction to this paper