Research Articles (Veterinary Tropical Diseases)

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Sequence- and structure-based bioinformatic screening for potential Theileria parva transport-related proteins
(Elsevier, 2026-02) Kotsovolos, Nikolaos; Schnittger, Leonhard; Sibeko-Matjila, Kgomotso Penelope; u14196973@tuks.co.za
As an obligate intracellular parasite, Theileria parva is strictly dependent on its host for nutrient acquisition. Transport proteins are expected to play a crucial role in the influx of essential nutrients to sustain the parasite’s rapid growth. Unfortunately, the T. parva transportome is still not comprehensively elucidated, and plagued by the presence of uncharacterized proteins. In this study, we employed a combination of approaches including sequence orthology and structural similarity to identify 188 proteins predicted to be involved in transport-related processes. Among these, 24 were uncharacterized proteins, and 17 of them could be assigned a tentative annotation. Furthermore, the localization of these 188 proteins was investigated, resulting in their assignment to seven cellular compartments. Screening of the proteomes of other Theileria species, T. annulata, T. orientalis, and T. equi revealed that all 188 proteins were present in both transforming and non-transforming Theileria parasites. Among the 188 potential transport-related proteins, 45 were associated with transmembrane transport and most of them (87 %) are conserved across phylum Apicomplexa. HIGHLIGHTS • A set of 188 potential transport-related proteins were identified in Theileria parva • Tentative annotations assigned to 17 transport-related uncharacterized proteins • Subcellular localization predicted for 153 of 188 proteins
Prioritising intervention areas for antimicrobial resistance in Nigeria's human and animal health sectors using a mixed-methods approach
(Elsevier, 2025-06) Awulu, Oche A.; Jenkins, Akinbowale; Balogun, Babatunde A.; Chukwu, Emelda E.; Fasina, Folorunso Oludayo; Egwuenu, Abiodun; Oduyebo, Oyinlola O.; Bamidele, Tajudeen A.; Cadmus, Simeon; Aworh, Mabel K.; Adekola, Adewole A.; Desbois, Andrew P.; Chah, Kennedy F.; Brunton, Lucy A.
A One Health approach is essential to prioritise intervention areas to tackle antimicrobial resistance (AMR). This study aimed to identify and evaluate critical drivers and antimicrobial stewardship (AMS) challenges within Nigeria's human and animal health sectors. Human (22) and animal (33) health professionals in Nigeria were asked via an online questionnaire to rank priority pathogens, AMS challenges, and AMR drivers identified by subject matter experts. Descriptive statistics and the Fisher's exact test were used to evaluate differences in rankings between sectors. Subsequently, a scoping literature review of peer-reviewed research and grey literature was conducted to evaluate the evidence supporting the rankings. Salmonella spp. (28.5 %) and Escherichia coli (28.2 %) were selected as the top-ranked priority pathogens for AMR. The Fisher's exact test showed a significant association (p = 0.049) between profession and ranking of Salmonella, which was ranked higher by animal health professionals than their human health counterparts. Priority AMS challenges in both human and animal health sectors were “ease of access to over-the-counter antimicrobials” (14.9 % and 20.1 %, respectively) and “lack of awareness of AMR/AMS” (14.1 % and 20.4 %, respectively). “Lack of infection prevention and control (IPC)” (24.5 %) was the highest-ranked AMR driver across sectors. Differences were observed between the rankings human and animal health professionals gave to the challenge of access to veterinary expertise (p = 0.011), as medical doctors ranked this component higher than veterinarians. “Lack of IPC” (p = 0.022) and “environmental degradation” (p = 0.048) were ranked higher by medical doctors than veterinarians. Conversely, “unsanitary processes in the abattoir(s)” was ranked higher among veterinarians (p = 0.032). Of the 84 articles reviewed, 62 supported the rankings of AMS challenges in both sectors, while 24 captured relevant AMR drivers. Our findings underscore the need for a One Health approach in Nigeria to improve AMS and curb AMR.
Antibiotic resistance profiles of oral flora in hippopotami (Hippopotamus amphibius) : implications for treatment of human bite wound infections
(BioMed Central, 2025-04) Michel, Anita Luise; Engelbrecht, Maralize; Roux, Francois; Wentzel, Jeanette Maria; Jonker, Annelize; anita.michel@up.ac.za
BACKGROUND : The common hippopotamus (Hippopotamus amphibius) is found in aquatic environments throughout sub-Saharan Africa and is known to cause attacks on humans living or working close to water bodies. Victims surviving an attack often suffer from the consequences of severe wound infections caused by the animal’s sharp canine teeth. OBJECTIVE : Isolation of normal flora bacteria from the oral cavity of common hippopotami (Hippopotamus amphibious) followed by antibiotic susceptibility testing to aid in the identification of a targeted antibiotic treatment regimen for hippopotamus attack victims. METHODS : Oral swabs were collected from 34 free-ranging hippopotami in three reserves within the Greater Kruger National Park Complex in South Africa and cultured for aerobic and anaerobic bacteria. Antibiotic susceptibility testing was conducted using the disc diffusion method (Kirby-Bauer method) and a panel of 16 antibiotic drugs representing 10 antibiotic categories. RESULTS : Culturing of 50 oral swab samples from 34 hippopotami yielded 188 aerobic isolates belonging to 30 bacterial genera and 41 bacterial species (Gram-negative: 70.7%; Gram-positive: 29.3%) and 16 obligate anaerobic isolates from two genera. Three bacterial species, namely Aeromonas hydrophila, Aeromonas sobria and Shewanella putrefaciens accounted for 52% of the aerobic isolates. The anaerobic isolates were identified as Prevotella melaninogenica and Clostridium spp. Antimicrobial susceptibility testing was performed for 112 aerobic isolates (Gram-negative: 93 (83%); Gram-positive: 19 (17%)) representing all isolated bacterial species. High levels of antibiotic resistance were observed among the Gram-negative species especially to most beta-lactam antibiotics (50.5% to 80.7%). Multidrug resistance was detected in 22.6% of Gram-negative isolates and in 24.1% of all isolates. CONCLUSIONS : This study provides the first investigation of the oral flora bacteria of the common hippopotamus. Among the 32 mostly aerobic bacterial genera the most abundant bacterial species were A. hydrophila, A. sobria and S. putrefaciens. They are typical inhabitants of the aquatic habitat of the hippopotamus and of zoonotic importance as opportunistic human pathogens. The antibiotic susceptibility profiles demonstrated that quinolones, aminoglycosides, and tetracyclines were highly efficacious against these bacterial species which otherwise showed moderate to high levels of resistance to the traditional bite wound treatment with amoxicillin/clavulanate and 1st and 2nd generation cephalosporins.
Perceptions on anthelmintic use and resistance development in goats under communal production systems
(BioMed Central, 2025-07) Ndwandwe, Khanyisani Cyril; Chimonyo, Michael; Tsotetsi-Khambule, Ana; Marufu, Munyaradzi Christopher; chris.marufu@up.ac.za
For decades, farmers relied on anthelmintic drug treatments to control gastrointestinal nematode (GIN) infections, which has led to the development of anthelmintic resistance (AR). The objective of this study was to investigate the perceptions of communal goat farmers regarding anthelmintic resistance in communal goat flocks. A structured, close-ended questionnaire was used to carry out face-to-face interviews with communal goat farmers (n = 384) across four local municipalities in the uMkhanyakude district. The results showed that elderly farmers were 1.4 times more likely to underdose compared to younger farmers (p < 0.05). Educated farmers were aware of the negative influence on AR development brought by using substandard drugs (p < 0.01) and repetitive use of one drug (p < 0.05). However, lack of professional veterinary assistance (p < 0.01) resulted in more than 65% of elderly farmers underdosing the anthelmintic drugs (p < 0.05) while 68% were using expired drugs (p < 0.05). Despite varying levels of education, most farmers treated goats only showing GIN infection signs (p < 0.05) in their flocks which can potentially delay the AR development. The elderly farmers are less likely to delay the development of AR due to their inability to adhere to the recognized principles of responsible and sustainable drug use. Despite reasonable awareness of AR as a problem in their flocks, communal farmers proved to have poor perceptions regarding the development of AR. This was attributed to old age, illiteracy and under dosing. Engaging veterinarians, farmers and animal health technicians could achieve sustainable management of GIN infections.
Temporal and spatial analysis of rabies virus lineages in South Africa
(MDPI, 2025-02) Viljoen, Natalie; Sabeta, Claude Taurai; Markotter, Wanda; Weyer, Jacqueline
Rabies virus (RABV; species Lyssavirus rabies) causes rabies, a disease of the central nervous system that invariably results in the death of the host. In South Africa, studies have indicated that RABV is maintained by animal species that include four wildlife carnivore species—the black-backed jackal (Canis mesomelas), bat-eared fox (Otocyon megalotis), yellow mongoose (Cynictis penicillata), and aardwolf (Proteles cristatus)—and domestic dogs (Canis lupus familiaris). The complex natural ecology holds significant implications for the control and elimination of rabies. In this study, confirmed animal rabies case data, including geospatial features, were analyzed for 12,879 laboratory-confirmed animal cases reported on a database managed by the Department of Agriculture, Land Reform and Rural Development (DALRRD). Sequence data generated from animal rabies cases in South Africa were also analyzed, which included 1374 cytoplasmic domain of the glycoprotein and the G-L intergenic sequences using maximum likelihood (ML) and Bayesian inference. The analysis provides insights into the transmission dynamics involving several wildlife species and domestic dogs in South Africa. This information is crucial for the strategic planning for rabies control and elimination programs, and particularly in understanding the interlinked nature of some lineages and the importance of the cross-border spread of rabies. This analysis provided an improved understanding of the distribution of the RABV lineages in South Africa and identified areas that can be targeted for rabies control strategies to limit future spread of RABV, which is important due to the limited available resources that must be carefully managed to allow optimal control.
A multi-modal investigation into the prevalence and diagnostic evaluation of vector-borne pathogens and retroviruses in domestic cats throughout Namibia
(Elsevier, 2025-08) De Villiers, Lourens; Penzhorn, Barend Louis; Schoeman, Johan P.; Molini, Umberto; De Villiers, Mari; Byaruhanga, Charles; Makgabo, Sekgota Marcus; Collins, Nicola E.; Zealand, Samantha; Baines, Ian J.M.; Stoltsz, Wilhelm Heinrich; Thompson, P.N. (Peter N.); Oosthuizen, Marinda C.
Neglected, but economically significant, tropical diseases may be prevalent in domestic cats of Namibia. A multi-centre prevalence field study was conducted across Namibia to assess the distribution of vector-borne pathogens and retroviruses from domestic cats. Samples of blood and serum from 280 cats in 15 towns across eight regions (22–51 cats per region) were analysed. Screening for Ehrlichia, Anaplasma, Babesia, and Hepatozoon species, as well as feline leukaemia virus (FeLV) and feline immunodeficiency virus (FIV), was conducted using light microscopy, point-of-care serology, and quantitative real-time polymerase chain reaction (qPCR) assays. Haematology and serum biochemistry analyses were also performed. Several pathogens were identified in Namibian cats using these diagnostic tools. Comparatively, pathogen detection rates varied by modality, namely light microscopy (5 %), serology (42 %), and qPCR (27 %). More specifically, microscopy revealed an overall prevalence (3 %) for inclusions resembling large Babesia parasites, serology indicated a seroprevalence for FIV antibodies (4 %) and FeLV antigen (40 %), and an overall prevalence determined by qPCR for E. canis (2 %) and H. canis (26 %). The investigation also demonstrated the associations between tick presence, pathogen infection, and disease manifestations in Namibian cats. A particular significant positive association was found between H. canis infection and FeLV antigen seroprevalence (P = 0.005). Overall, the study highlighted the difference of various diagnostic tools for detecting pathogen prevalence in cats. Appropriate diagnostic testing - informed by known associations with disease manifestation - should be key in guiding responsible treatment strategies and evaluating potential zoonotic risks linked to domestic cats of Namibia. HIGHLIGHTS • First comprehensive survey of vector-borne diseases and retroviruses in domestic cats across several Namibian regions. • First confirmed detection of Ehrlichia canis and Hepatozoon canis in domestic feline blood across several regions of Namibia. • Demonstrated significant associations between pathogen infection, tick presence, and disease manifestation.
Ehrlichia ruminantium (Ehrlichiaceae) infection rates and genotyping in Amblyomma species from southern Africa
(Elsevier, 2025-05) Smit, Andeliza; Mulandane, Fernando C.; Wojcik, Stephane H; Malabwa, Choolwe; Sili, Gourgelia; Mandara, Stephen; Pineau, Kaissa Plaisir; Lecollinet, Sylvie; Exbrayat, Antoni; Rodrigues, Valerie; Vineer, Hannah Rose; Dlamkile, Zinathi; Stoltsz, Wilhelm Heinrich; Meyer, Damien F.; Morar-Leather, Darshan; Makepeace, Benjamin L.; Neves, L.C.B.G.D. (Luís); u14023190@tuks.co.za
Ticks are haematophagous ectoparasites of domestic and wild animals. With their vast geographical distribution and aptitude as vectors of a large variety of pathogens, they are ranked amongst the top two arthropod families of veterinary and medical concern. Amblyomma, the third largest genus in the Ixodidae, is important in southern Africa due to its vector competence for Ehrlichia ruminantium and other pathogens. Ehrlichia ruminantium, the causative agent of heartwater, a potentially lethal disease in ruminants, is classified as a notifiable disease by the World Organisation for Animal Health. Amblyomma species ticks were collected in five southern African countries from livestock and wildlife. They were morphologically identified to species level with taxonomic keys, and species identity was confirmed with molecular assays. Preliminary screening for E. ruminantium was conducted by targeting the pCS20 gene fragment. Genotyping of 39 E. ruminantium positives was obtained using Ampliseq technology. In total, 7,734 Amblyomma ticks were collected and identified as belonging to four species: Amblyomma eburneum, Amblyomma hebraeum, Amblyomma pomposum and Amblyomma variegatum. Ehrlichia ruminantium infection rates per country ranged from 7.1 % to 34.1 %. The genotyping analysis indicated the clustering of our sequences with strains Gardel, Welgevonden, Um Banein, Springbokfontein 4 and 2, Kwanyanga, and Blaauwkrans. The Ampliseq analysis was not effective in differentiating between strains found in southern Africa. This large study documents the genetic diversity and prevalence of E. ruminantium in ticks across southern Africa, highlighting implications for disease control and vaccine development.
In vitro infection of bovine erythrocytes with Theileria annulata merozoites as a key step in completing the T. annulata life cycle in vitro
(Nature Research, 2024-02-13) Elati, Khawla; Tajeri , Shahin; Mugo , Robert M.; Obara , Isaiah; Darghouth, Mohamed Aziz; Zweygarth, Erich; Nijhof, Ard Menzo
Theileria annulata is a protozoan parasite with a complex life cycle involving a bovine host and a tick vector. It is transmitted by Hyalomma ticks and is the causative agent of tropical theileriosis, a debilitating and often fatal disease in southern Europe, northern Africa and large parts of Asia. Understanding the biology of different life cycle stages is critical for the control of tropical theileriosis and requires the use of experimental animals which poses an ethical concern. We present for the first time the in vitro infection of red blood cells (RBCs) with T. annulata differentiated schizonts. The Ankara cell line of T. annulata was cultured at 41 °C for nine days to induce merogony and subsequently incubated with purified RBCs for one to three days. Percentage of parasitized erythrocyte (PPE) over the short culture period was estimated by Giemsa staining (0.007–0.01%), Flow cytometry activated sorting (FACS) (0.02–1.1%) and observation of FACS sorted cells by confocal microscopy (0.05–0.4%). There was a significant difference in the PPE between FACS and the two other techniques (one-way ANOVA followed by Tukey test, P = 0.004) but no significant difference was observed between the confocal imaging and Giemsa staining methods (ANOVA one-way followed by Tukey test, P = 0.06). Importantly, all three complementary methods confirmed the invasion of RBCs by T. annulata merozoites in vitro. Although the experimental conditions will require further optimization to increase the PPE, the in vitro infection of RBCs by T. annulata merozoites is pivotal in paving the way for the eventual completion of the T. annulata life cycle in vitro when combined with artificial tick feeding.
Indigenous ethno-nutraceutical plants : potential game-changers for the dual management of ruminant helminths and undernutrition in sub-Saharan Africa
(Elsevier, 2025-07) Mapiye, Cletos; Semwogerere, Farouk; Mahachi, Leo Nyikadzino; Mwale, Marizvikuru; Marufu, Munyaradzi Christopher
ETHNOPHARMACOLOGOCAL RELEVANCE : Ruminant productivity in sub-Saharan Africa (SSA) remains low largely due to helminth infections coupled with undernutrition. To jointly boost ruminant health and nutritional status, rural farmers in SSA often resort to indigenous ethno-nutraceutical plants (iENPs), which form part of folkloric practices perceived to be more accessible, affordable and effective compared with chemotherapy which is challenged by helminth resistance. However, these perceived advantages are largely unsubstantiated. AIM OF THE STUDY : The current review aimed to 1) identify iENPs used as ruminant anthelminthic and undernutrition remedies in SSA, 2) document their bio-efficiency, mode of action, safety, and optimal application conditions and 3) highlight priority areas for further research. MATERIALS AND METHODS : A PRISMA approach-based search of literature from the past three decades was performed in several electronic academic research databases and accredited scholarly repositories. RESULTS : The review identified 15 iENPs from 88 scientific articles. The Vachellia and Vernonia species possessing polyphenols, saponins and essential oils as the dominant phytochemicals demonstrated the highest anthelminthic and nutritional potency. However, for most iENPs, nutrients and phytochemicals have not been fully profiled, optimal conditions of application are not yet ascertained, bio-efficiency is highly variable, mode of action remains unclear, and safety limits are unknown. CONCLUSION : To exploit the full potential of SSA's iENPs as anthelminthic and undernutrition remedies for ruminants, the review advocates for a holistic, transdisciplinary regional approach focusing on identifying key phytochemicals in indigenous plants, validating their bio-efficacy and mechanisms of action, determining safety limits, and optimizing application conditions using least-cost technologies.
UP maak deurbraak met beesaborsie-diagnose
(Plaas Publishing, 2025-03) Marais, Susan; melvyn.quan@up.ac.za
Navorsers aan die Universiteit van Pretoria (UP) is positief dat hulle 'n deurbraak gemaak het om een van die beeswêreld se grootste probleme te help oplos, naamlik die redes waarom koeie aborteer.
Decoding the anomalies : a genome-based analysis of Bacillus cereus group strains closely related to Bacillus anthracis
(Frontiers Media, 2025-02) Magome, Thuto Gomolemo; Surleac, Marius; Hassim, Ayesha; Bezuidenhout, Cornelius Carlos; Van Heerden, Henriette; Lekota, Kgaugelo Edward
INTRODUCTION : The Bacillus cereus group encompasses a complex group of closely related pathogenic and non-pathogenic bacterial species. Key members include B. anthracis, B. cereus, and B. thuringiensis organisms that, despite genetic proximity, diverge significantly in morphology and pathogenic potential. Taxonomic challenges persist due to inconsistent classification methods, particularly for B. cereus isolates that resemble B. anthracis in genetic clustering. METHODS : This study investigated B. cereus group isolates from blood smears of animal carcasses in Kruger National Park, uncovering an unusual isolate with B. cereus features based on classical microbiological tests yet B. anthracis-like genomic similarities with an Average Nucleotide Identity (ANI) of ≥95%. Using comparative genomics, pan-genomics and whole genome Single Nucleotide Polymorphism (wgSNP) analysis, a total of 103 B. cereus group genomes were analyzed, including nine newly sequenced isolates from South Africa and a collection of isolates that showed some classification discrepancies, thus classified as “anomalous.” RESULTS AND DISCUSSION : Of the 36 strains identified as B. anthracis in GenBank, 26 clustered phylogenetically with the four confirmed B. anthracis isolates from South Africa and shared 99% ANI. Isolates with less than 99% ANI alignment to B. anthracis exhibited characteristics consistent with B. cereus and/or B. thuringiensis, possessing diverse genetic profiles, insertion elements, resistance genes, and virulence genes features, contrasting with the genetic uniformity of typical B. anthracis. The findings underscore a recurrent acquisition of mobile genetic elements within B. cereus and B. thuringiensis, a process infrequent in B. anthracis. CONCLUSION : This study highlights the pressing need for standardized taxonomic criteria in B. cereus group classification, especially as anomalous isolates emerge. This study supports the existing nomenclature framework which offers an effective solution for classifying species into genomospecies groups. We recommend isolates with ANI ≥99% to standard reference B. anthracis be designated as typical B. anthracis in GenBank to maintain taxonomic clarity and precision.
Rhinoceromics : a multi-amplicon study with clinical markers to transferrin saturation levels in ex-situ black rhinoceros (Diceros bicornis michaeli)
(Frontiers Media, 2025-05) Bruins-van Sonsbeek, Linda G.R.; Verschuren, Martie C.M.; Kaal, Sonja; Lindenburg, Peter W.; Rodenburg, Kees (C.) W.; Clauss, Marcus; Speksnijder, Arjen G.C.L.; Rutten, Victor P.M.G.; Bonnet, Bas F.J.; Wittink, Floyd
Iron overload disorder (IOD) is a common condition in ex-situ black rhinoceroses (Diceros bicornis), although it has not been reported in the wild. This study aimed to gain a deeper understanding of the relationship between 25-hydroxy vitamin D [25(OH)D], inflammatory markers, insulin levels, the gut microbiome, dietary components, and transferrin saturation (TS) in ex-situ black rhinoceroses. Blood and fecal samples from 11 black rhinoceroses at five different European zoological institutions were monitored over a 1-year period. Inflammatory markers such as interleukin 6 (IL-6), serum amyloid A (SAA), interferon γ (IFN-γ), and tumor necrosis factor α (TNF-α) were analyzed. Our study corroborates the findings of previous research, which demonstrated that insulin, inflammatory markers, and TS% are higher in ex-situ black rhinoceroses compared to published wild ranges. Our data show no correlations between insulin, 25(OH)D, TS%, inflammatory markers, or short-chain fatty acids (SFCAs). Serum 25(OH)D exhibited significantly higher levels in summer than in winter. Transferrin saturation was influenced by age, which is consistent with previous studies. The microbiome did not differ significantly among individuals, institutions, sex, or season, unlike the mycobiome, which exhibited significant differences across institutions. The impact of the mycobiome differences on the physiology of the animals could not be determined from this study.
Evaluating the efficacy of bioelectrical impedance analysis using machine learning models for the classification of goats exposed to Haemonchosis
(Frontiers Media, 2025-05) Siddique, Aftab; Batchu, Phaneendra; Shaik, Arshad; Gurrapu, Priyanka; Erukulla, Tharun Tej; Ellington, Cornileus; Villa, Andrea L. Rubio; Brown, Davia; Mahapatra, Ajit; Panda, Sudhanshu; Morgan, Eric; Van Wyk, Jan Aucamp; Shapiro-Ilan, David; Kannan, Govind; Terrill, Thomas H.
Rapid identification and assessment of animal health are critical for livestock productivity, especially for small ruminants like goats, which are highly susceptible to blood-feeding gastrointestinal nematodes, such as Haemonchus contortus. This study aimed at establishing proof of concept for using bioelectrical impedance analysis (BIA) as a non-invasive diagnostic tool to classify animals at different levels of Haemonchosis. A cohort of 94 intact Spanish bucks (58 healthy; 36 Unhealthy; naturally infected with H. contortus) was selected to evaluate the efficacy of BIA through the measurement of resistance (Rs) and electrical reactance (Xc). Data were collected from live goats using the CQR 3.0 device over multiple time points. The study employed several machines learning models, including Support Vector Machines (SVM), Backpropagation Neural Networks (BPNN), k-Nearest Neighbors (K-NN), XGBoost, and Keras deep learning models to classify goats based on their bioelectrical properties. Among the classification models, SVM demonstrated the highest accuracy (95%) and F1-score (96%), while K-NN showed the lowest accuracy (90%). For regression tasks, BPNN outperformed other models, with a nearly perfect R2 value of 99.9% and a minimal Mean Squared Error (MSE) of 1.25e-04, followed by SVR with an R2 of 96.9%. The BIA data revealed significant differences in Rs and Xc between lightly and more heavily Unhealthy goats, with the latter exhibiting elevated resistance values, likely due to dehydration and tissue changes resulting from Haemonchosis. These findings highlight the potential of BIA combined with machine learning to develop a scalable, rapid, and non-invasive diagnostic tool for monitoring small ruminant health, particularly in detecting parasitic infections like H. contortus. This approach could improve herd management, reduce productivity losses, and enhance animal welfare.
Factors influencing the frequency, knowledge, attitudes and practices of antibiotic use in commercial layer chicken farms, Tanzania
(Frontiers Media, 2025-04) Mdemu, Siha; Matondo, Augustine B.; Christensen, Jens Peter; Amasha, Ahmed E.; Ngowi, Helena A.; Westwood, Erica; Ochai, Sunday Ochonu; Nonga, Hezron E.; Osbjer, Kristina; Mdegela, Robinson H.
INTRODUCTION : Indiscriminate use of veterinary antibiotics significantly contributes to the current antibiotic resistance in the world. The primary objective of this study was to explore the factors that could influence knowledge, attitudes and practices of antibiotic use in commercial layer farms. METHODS : A cross-sectional study was conducted to evaluate antibiotic use patterns and their associated factors among layer chicken farmers in Tanzania. The study surveyed 205 farmers randomly selected from three regions: Unguja, Morogoro, and Dar es Salaam. Data were analysed using descriptive statistics, while negative binomial and multiple linear regression models were employed to identify factors influencing antibiotic usage patterns. RESULTS : A widespread use of antibiotics was revealed, with 97.1% of farmers using antibiotics for treatment, prophylaxis and/or increasing egg productivity. The most commonly used antibiotics were oxytetracycline (63%), doxycline-tylosin combination (29.8%) and enrofloxacin (22.4%). Notably, 95.6% of farmers reported that they do not observe withdrawal periods. Assessment of farmers' knowledge, attitudes, and practices yielded mean scores of 55.5%, 69.1% and 50.9% respectively. Furthermore, older adults and individuals with primary education were more likely to have higher attitude scores. Geographic location and flock size are among other factors that are likely to influence knowledge and attitudes towards antibiotic use. Higher frequency of antibiotic use was significantly associated with young adults, medium-scale farm operators, and farmers in Morogoro region (compared to the other two regions). CONCLUSION : The frequency, knowledge, attitude and practices related to the use of antibiotics were affected by scale of production, location, age, and education. These findings provide insights into antibiotic stewardship among layer farmers that could suggest future multifaceted interventions to promote prudent use of antibiotics, hence mitigating risk of antibiotic resistance.
First detection of Amblyomma lepidum (Dönitz, 1909) in Zimbabwe
(Springer, 2025-04) Smit, Andeliza; Mandara, Stephen; Dlamkile, Zinathi; Morar-Leather, Darshana; Bosman, Anna-Mari; Neves, Luís C.B.G.
Herewith we present the first detection of Amblyomma lepidum (Dönitz, 1909) on cattle in Zimbabwe. Zimbabwe’s smallholder farmers rely heavily on their livestock, mainly cattle and goats. Even though great importance is placed on cattle farming, no systematic surveillance of tick and tick-borne diseases is currently being conducted in the country. Forming part of the Amblyomma genus, A. lepidum is a brightly ornate tick with great vector potential, which could have harmful effects on cattle and cattle farming in Zimbabwe. This report documents the presence of both male and female A. lepidum ticks that were morphologically identified, and with the use of two ribosomal genes, were molecularly characterised as A. lepidum. Hypotheses can be made as to how this tick was introduced into Zimbabwe; however, its presence highlights the need for a systematic surveillance programme to track not only new introductions, such as the aforementioned, but the current distribution of this tick population in Zimbabwe.
Elimination of dog-mediated human rabies : scientific tools, one health and partnerships
(Office International des Epizooties, 2024-12) Blumberg, Lucille Hellen
A world free of dog-mediated human rabies by 2030 would be an outstanding achievement. This ambitious goal for a neglected tropical disease, set by the World Organisation for Animal Health (WOAH), the World Health Organization, the Food and Agriculture Organization of the United Nations and the Global Alliance for Rabies Control together with partners and countries, has a clear and achievable pathway to success. In the 100 years since the inception of WOAH, many scientific tools have been developed to support the elimination of dog-mediated rabies. In addition to these tools, engaging communities and health workers to build awareness to prevent bite exposures, managing dog populations and ensuring herd immunity through dog vaccination are key to achieving the elimination goals. The provision of post-exposure prophylaxis and care for exposed victims are important interventions on the human side. Success in eradicating rabies will require applying a One Health approach, an integrative and systemic approach to health grounded in the understanding that human health is closely linked to animal and environmental health. Political commitment and availability of adequate resources are key to achieving the Zero by 2030 goal.
A One Health perspective on Salmonella enterica Serovar Infantis, an emerging human multidrug-resistant pathogen
(Centers for Disease Control and Prevention (CDC), 2024-04) Mattock, Jennifer; Chattaway, Marie Anne; Hartman, Hassan; Dallman, Timothy J.; Smith, Anthony Marius; Keddy, Karen H.; Petrovska, Lilijana; Manners, Emma J.; Duze, Sanelisiwe T.; Smouse, Shannon; Tau, Nomsa; Timme, Ruth; Baker, Dave J.; Mather, Alison E.; Wain, John; Langridge, Gemma C.
Salmonella enterica serovar Infantis presents an ever increasing threat to public health because of its spread throughout many countries and association with high levels of antimicrobial resistance (AMR). We analyzed whole genome sequences of 5,284 Salmonella Infantis strains from 74 countries, isolated during 1989–2020 from a wide variety of human, animal, and food sources, to compare genetic phylogeny, AMR determinants, and plasmid presence. The global Salmonella Infantis population structure diverged into 3 clusters: a North American cluster, a European cluster, and a global cluster. The levels of AMR varied by Salmonella Infantis cluster and by isolation source; 73% of poultry isolates were multidrug resistant, compared with 35% of human isolates. This finding correlated with the presence of the pESI megaplasmid; 71% of poultry isolates contained pESI, compared with 32% of human isolates. This study provides key information for public health teams engaged in reducing the spread of this pathogen.
Identification of ticks and tick-borne pathogens of wildlife necropsy cases submitted to the SANBI National Zoological Gardens, South Africa
(Elsevier, 2024-10) Khumalo, Nozipho; Ledwaba, Maphuti Betty; Labuschagne, Kim; Vorster, Ilse; Oosthuizen, Marinda C.; Mwale, Monica; Chaisi, Mamohale E.
Ticks are arachnid blood-feeding parasites, which infest livestock, wildlife, and humans, transmitting medically and veterinary significant pathogens. Their biodiversity and distribution in wild animals remains complex. This study analysed archived tick samples (n = 48) from the South African Biodiversity Institute (SANBI) Wildlife Biobank utilizing morphology and genetic analyses of the 16S rRNA and COI (DNA barcoding) mitochondrial genes to identify ticks collected among 13 vertebratesavian, reptilian, and mammalian host species. The specimens came from nine localities including nature reserves and captive facilities (zoological garden) in South Africa, Namibia, and Botswana. These ticks were also assessed for associated pathogens with the reverse line blot (RLB) hybridization assay. Seven tick genera, Amblyomma, Hyalomma, Haemaphysalis, Ixodes, Rhipicephalus, Rhipicentor, and Otobius were identified, with Amblyomma being the most prevalent (22.9 %) in our sample set. Obtained sequences were 95–100 % similar to published records of tick species collected from wild and domestic animals, as well as those collected from vegetation, from different southern African areas. However, tick specimens (n = 3) identified morphologically as Hyalomma truncatum, Rhipicephalus e. evertsi, and R. simus, were, on a molecularly level, more closely related to their sister taxa (H. glabrum, R. e. mimeticus, and R. gertrudae, respectively) suggesting a need for taxonomic verification. With the RLB hybridization assay, six samples reacted with the Ehrlichia/Anaplasma genus-specific probe, while two reacted with the Theileria/Babesia genus-specific probe. Sequencing of the RLB amplicons targeting the 18S rRNA gene (n = 2) indicated 100 % similarity to Hepatozoon fitzsimonsi, while one was closely related to He. ingwe with 99.39 % similarity. The results show that wildlife harbour different tick species, and pathogen detection identified novel genotypes, indicating wildlife as potential pathogens reservoirs. This study enhances our understanding of tick biodiversity, distribution and highlights wildlife's role in harbouring diverse tick species and novel pathogens.
Development and validation of a real-time PCR assay, and phylogenetic analysis of Anaplasma platys
(Elsevier, 2025-07) Nkosi, Nokuzola Faith; Byaruhanga, Charles; Arega, Sintayehu M.; Conan, Anne; Knobel, Darryn Leslie; Oosthuizen, Marinda C.; Quan, Melvyn; melvyn.quan@up.ac.za
Anaplasmosis is a tick-borne disease caused by species of the genus Anaplasma. In dogs anaplasmosis is caused by Anaplasma phagocytophilum and Anaplasma platys. These bacteria are in the family Anaplasmataceae in the order Rickettsiales. Anaplasma platys is a Gram-negative bacterium that is of public health and veterinary importance. This pathogen exclusively infects platelets and causes infectious cyclic thrombocytopenia in dogs. Infection occurs through the bite of an infected ixodid tick, Rhipicephalus sanguineus, which is the principal vector and is also known to transmit Ehrlichia canis, another bacteria of veterinary importance. Our group recently reported on the developed group-specific Ehrlichia/Anaplasma primers and the A. platys-specific TaqMan® Minor Groove Binder probe for multiplexing purposes. This study validated the A. platys TaqMan® PCR assay targeting the 16S rRNA gene. Furthermore, phylogenetic analysis was used to characterize A. platys. The assay efficiency was 94.9 %, and the 95 % limit of detection (LOD) was 5.08 A. platys plasmid copies/μl blood with a 95 % confidence interval of 3.1–10.2. The assay did not cross-react when tested against other haemoparasites. The phylogenetic characterization of the Mnisi community samples revealed that the A. platys sequences from this area grouped with other A. platys sequences from South Africa and other countries, including India, Zambia, Taiwan, Thailand, and Croatia. The developed TaqMan® qPCR assay will be a valuable tool for the early diagnosis of A. platys by preventing inappropriate use of antibiotics and alleviating potential emerging antimicrobial resistance. Additionally, early detection and administration of the correct antibiotics speed recovery time.
Roles of host and environment in shift of primary anthrax host species in Kruger National Park
(Public Library of Science, 2024-12-06) Ochai, Sunday Ochonu; Snyman, Lourens Fourie; Dolfi, Amelie C.; Ramoelo, Abel; Reilly, Brian K.; Botha, Judith M.; Dekker, Edgar H.; Van Schalkwyk, Ockert Louis; Kamath, Pauline L.; Archer, Emma Rosa Mary; Turner, Wendy C.; Van Heerden, Henriette
Environmental and climatic factors, as well as host demographics and behaviour, significantly influence the exposure of herbivorous mammalian hosts to pathogens such as Bacillus anthracis, the causative agent of anthrax. Until the early 1990s in Kruger National Park (KNP), kudu (Tragelaphus strepsiceros) was the host species most affected by anthrax, with outbreaks occurring predominantly in the dry season, particularly during drought cycles. However, the most affected host species has shifted to impala (Aepyceros melampus), with more frequent anthrax outbreaks during the wet season. This study investigates the roles of environmental variation and other host species in this shift. Temporal trends in environmental variables such as precipitation, soil moisture, temperature, and normalised difference vegetation index (NDVI) were analyzed in relation to anthrax occurrence (presence/ absence and counts). Additionally, correlations between host species' densities and anthrax mortalities over time were examined. Anthrax cases in 1990 were concentrated in the central and northern regions of KNP (excluding Pafuri), primarily affected kudus; while subsequent mortalities affected mostly impala and were restricted to the far north, in Pafuri. Significant correlations were found between kudu anthrax mortality and a decrease in NDVI, average temperature, SPI-6 and SPI-12 (Standardised Precipitation Index in various time intervals. Conversely, anthrax occurrence in impalas was associated with a decline in SPI-3, and temperature rise, with increased mortality during the rainy season. Elephant density correlated negatively with kudu mortality, but a positive correlation with both impala mortality and impala density. The study concludes that environmental variables and species' densities may alter the diversity and frequency of hosts exposed to B. anthracis. Climate extremes and alterations therein may exacerbate anthrax severity by modifying species susceptibility and their probability of exposure over time.

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