Disease control tools to secure animal and public health in a densely populated world

Improve animal health to reduce livestock emissions: quantifying an open goal

Greenhouse gas (GHG) emissions from livestock production must be urgently tackled to substantially reduce their contribution to global warming. Simply reducing livestock numbers to this end risks impacting negatively on food security, rural livelihoods and climate change adaptation. We argue that significant mitigation of livestock emissions can be delivered immediately by improving animal health and hence production efficiency, but this route is not prioritized because its benefits, although intuitive, are poorly quantified. Rigorous methodology must be developed to estimate emissions from animal disease and hence achievable benefits from improved health through interventions. If, as expected, climate change is to affect the distribution and severity of health conditions, such quantification becomes of even greater importance. We have therefore developed a framework and identified data sources for robust quantification of the relationship between animal health and greenhouse gas emissions, which could be applied to drive and account for positive action. This will not only help mitigate climate change but at the same time promote cost-effective food production and enhanced animal welfare, a rare win-win in the search for a sustainable planetary future.

Control of companion animal parasites and impact on One Health

The last decades have witnessed an increase in the global population and movements of companion animals, contributing to changes in density and distribution of pet parasites. Control of companion animal parasites (CAPs) becomes increasingly relevant because of the intensifying human-animal bond. Parasites impact on the health of humans and their pets, but also of wildlife and the environment. We conducted a qualitative review on the current advancements, gaps and priorities for the monitoring and treatment of CAPs with a focus on securing public health. There is a need to raise awareness, coordinate global surveillance schemes and better quantify the impact of companion animal parasites on One Health.

Inactivation of highly transmissible livestock and avian viruses including influenza A and Newcastle disease virus for molecular diagnostics

There is a critical need for an inactivation method that completely inactivates pathogens at the time of sample collection while maintaining the nucleic acid quality required for diagnostic PCR testing. This inactivation method is required to alleviate concerns about transmission potential, minimize shipping complications and cost, and enable testing in lower containment laboratories, thereby enhancing disease diagnostics through improved turn-around time. This study evaluated a panel of 10 surrogate viruses that represent highly pathogenic animal diseases. These results showed that a commercial PrimeStore® molecular transport media (PSMTM) completely inactivated all viruses tested by >99.99%, as determined by infectivity and serial passage assays. However, the detection of viral nucleic acid by qRT-PCR was comparable in PSMTM and control-treated conditions. These results were consistent when viruses were evaluated in the presence of biological material such as sera and cloacal swabs to mimic diagnostic sample conditions for non-avian and avian viruses, respectively. The results of this study may be utilized by diagnostic testing laboratories for highly pathogenic agents affecting animal and human populations. These results may be used to revise guidance for select agent diagnostic testing and the shipment of infectious substances.

Diet composition drives tissue-specific intensity of murine enteric infections

Diet composition plays a large role in regulating gut health and enteric infection. In particular, synthetic "Western-style" diets may predispose to disease, while whole-grain diets containing high levels of crude fiber are thought to promote gut health. Here, we show that, in contrast to this paradigm, mice fed with unrefined chow are significantly more susceptible to infection with Trichuris muris, a caecum-dwelling nematode, than mice fed with refined, semi-synthetic diets (SSDs). Moreover, mice fed with SSD supplemented with inulin, a fermentable fiber, developed chronic T. muris burdens, whereas mice fed with SSD efficiently cleared the infection. Diet composition significantly impacted infection-induced changes in the host gut microbiome. Mice infected with the bacterium Citrobacter rodentium were also more susceptible to pathogen colonization when fed with either chow or inulin-enriched SSD. However, transcriptomic analysis of tissues from mice fed with either SSD or inulin-enriched SSD revealed that, in contrast to T. muris, increased C. rodentium infection appeared to be independent of the host immune response. Accordingly, exogenous treatment with interleukin (IL)-25 reduced T. muris burdens in inulin-fed mice, whereas IL-22 treatment was unable to restore resistance to C. rodentium colonization. Diet-mediated effects on pathogen burden were more pronounced for large intestine-dwelling pathogens, as effects on small the intestinal helminth (Heligmosomoides polygyrus) were less evident, and protozoan (Giardia muris) infection burdens were equivalent in mice fed with chow, inulin-enriched SSD, or SSD, despite higher cyst excretion in chow-fed mice. Collectively, our results point to a tissue- and pathogen-restricted effect of dietary fiber levels on enteric infection intensity.IMPORTANCEEnteric infections induce dysbiosis and inflammation and are a major public health burden. As the gut environment is strongly shaped by diet, the role of different dietary components in promoting resistance to infection is of interest. While diets rich in fiber or whole grain are normally associated with improved gut health, we show here that these components predispose the host to higher levels of pathogen infection. Thus, our results have significance for interpreting how different dietary interventions may impact on gastrointestinal infections. Moreover, our results may shed light on our understanding of how gut flora and mucosal immune function is influenced by the food that we eat.

Antimicrobial use and resistance in food animal production: food safety and associated concerns in Sub-Saharan Africa

The use of antimicrobials in food animal (FA) production is a common practice all over the world, with even greater usage and dependence in the developing world, including Sub-Saharan Africa (SSA). However, this practice which serves obvious economic benefits to producers has raised public health concerns over the last decades, thus driving the selection and dissemination of antimicrobial resistance and adversely impacting food safety and environmental health. This review presents the current and comprehensive antimicrobial usage practices in food animal production across SSA. We further highlighted the overall regional drivers as well as the public health, environmental, and economic impact of antimicrobial use in the production of food animals. Antimicrobial use is likely to increase with even exacerbated outcomes unless cost-effective, safe, and sustainable alternatives to antibiotics, especially probiotics, prebiotics, bacteriocins, antimicrobial peptides, bacteriophages, vaccines, etc. are urgently advocated for and used in food animal production in SSA. These, in addition to the implementation of strong legislation on antimicrobial use, and improved hygiene will help mitigate the public health concerns associated with antimicrobial use in food animals and improve the well-being and safety of food animals and their products.

Rift Valley fever in West Africa: A zoonotic disease with multiple socio-economic consequences

Rift Valley fever virus (RVFV) is an arbovirus that causes Rift Valley fever (RVF), a zoonotic disease that mainly affects domestic and wildlife ruminants and humans. The first epidemic in North-Western and West Africa occurred in Senegal and Mauritania in 1987, two countries where RVF is now endemic. Slaughterhouse workers, farmers, herders and veterinarians are at high risk of exposure to RVF. Beyond the health threat, RVF is considered to cause major socio-economic problems, specifically in developing countries where livestock farming and trade are important economic activities. Indeed, the mortality rate linked to RVF infection can reach 95-100% in newborns and young animals. In West Africa, livestock production is a key factor for food production and for national economics. Epizootics caused by RVF can therefore have serious socio-economic consequences by impacting multisectoral economics, the psycho-social health of pastoral communities, and food security. Improving prevention strategies against RVF, including vaccination, enhancing knowledge of RVF and correcting any inappropriate behaviors by populations of endemics areas, as well as better monitoring of RVF ecological factors are effective ways to better foresee and control outbreaks of RVF and its socio-economical side-effects in countries at high risk of occurrence of the disease.

Management of diseases in a ruminant livestock production system: a participatory appraisal of the performance of veterinary services delivery, and utilization in Ghana

INTRODUCTION

Sustainable livestock production remains crucial for attainment of food security globally and for safeguarding the livelihoods of many households in low- and -middle income countries. However, the high prevalence of infectious livestock diseases, coupled with inadequate provision and adoption of effective control measures, leads to reduced livestock productivity, increased animal mortalities, and emergence of antimicrobial resistant pathogens. This study sought to assess the management strategies employed by farmers for priority diseases affecting their animals and the utilization and performance of veterinary services.

METHODS

We conducted the study in three districts, namely, Mion, Pru East, and Kwahu Afram Plains South Districts, which represent the main livestock production belts in Ghana. We used questionnaires in surveys, to collect pertinent data from 350 ruminant livestock farmers and 13 professional veterinary officers (VOs) in the study districts. Additionally, we conducted seven focus group discussions (FGDs) with 65 livestock farmers in the study districts. The survey data was analyzed, and we describe the distribution of the priority livestock diseases, the disease management strategies employed, and the performance of veterinary services in Ghana. We also analyzed the raw FGD transcript texts deductively based on the study objectives. To validate findings across the different datasets, we used triangulation.

RESULTS

Almost all the farmers (98%) reared small ruminants, with about 25% also rearing cattle. The main priority livestock diseases identified includes pestes-des-petits-ruminants and mange infection in sheep and goats, as well as contagious bovine pleuropneumonia and foot-and-mouth-disease in cattle. We found that majority (82%) of the farmers relied on treatment, while only 20% opted for vaccination services. Additionally, the veterinary system in Ghana did not adequately regulate the antimicrobial medications employed by farmers to manage diseases. Thus, in most of the cases, the medicines applied by farmers were not useful for the target diseases. Although our findings show the farmers perceived VOs to perform highly compared to informal providers on most of the attributes evaluated including medicine availability and quality, treatment effectiveness, advisory services, service affordability, and competence, only 33% utilized VOs services. The majority of the farmers (51%) used the services of informal providers, who were better in proximity and popularity with farmers.

CONCLUSIONS

The livestock sector in Ghana faces a substantial challenge due primarily to vaccine-preventable diseases. Even though VOs demonstrated superior performance on key veterinary service performance indicators, their services are underutilized by livestock farmers. Additionally, the absence of regulatory oversight by the veterinary system over antimicrobials utilized in animal production contributes to their misapplication by livestock farmers, posing a considerable risk to both public health and food security. It is thus imperative to introduce new initiatives that enhance the uptake of animal vaccines and better antimicrobial stewardship to ensure sustainable livestock production.

Host-pathogen interactions under pressure: A review and meta-analysis of stress-mediated effects on disease dynamics

Human activities have increased the intensity and frequency of natural stressors and created novel stressors, altering host-pathogen interactions and changing the risk of emerging infectious diseases. Despite the ubiquity of such anthropogenic impacts, predicting the directionality of outcomes has proven challenging. Here, we conduct a review and meta-analysis to determine the primary mechanisms through which stressors affect host-pathogen interactions and to evaluate the impacts stress has on host fitness (survival and fecundity) and pathogen infectivity (prevalence and intensity). We assessed 891 effect sizes from 71 host species (representing seven taxonomic groups) and 78 parasite taxa from 98 studies. We found that infected and uninfected hosts had similar sensitivity to stressors and that responses varied according to stressor type. Specifically, limited resources compromised host fecundity and decreased pathogen intensity, while abiotic environmental stressors (e.g., temperature and salinity) decreased host survivorship and increased pathogen intensity, and pollution increased mortality but decreased pathogen prevalence. We then used our meta-analysis results to develop susceptible-infected theoretical models to illustrate scenarios where infection rates are expected to increase or decrease in response to resource limitations or environmental stress gradients. Our results carry implications for conservation and disease emergence and reveal areas for future work.

Nipah Virus: An Overview of the Current Status of Diagnostics and Their Role in Preparedness in Endemic Countries

Nipah virus (NiV) is a paramyxovirus responsible for a high mortality rate zoonosis. As a result, it has been included in the list of Blueprint priority pathogens. Bats are the main reservoirs of the virus, and different clinical courses have been described in humans. The Bangladesh strain (NiV-B) is often associated with severe respiratory disease, whereas the Malaysian strain (NiV-M) is often associated with severe encephalitis. An early diagnosis of NiV infection is crucial to limit the outbreak and to provide appropriate care to the patient. Due to high specificity and sensitivity, qRT-PCR is currently considered to be the optimum method in acute NiV infection assessment. Nasal swabs, cerebrospinal fluid, urine, and blood are used for RT-PCR testing. N gene represents the main target used in molecular assays. Different sensitivities have been observed depending on the platform used: real-time PCR showed a sensitivity of about 103 equivalent copies/reaction, SYBRGREEN technology's sensitivity was about 20 equivalent copies/reaction, and in multiple pathogen card arrays, the lowest limit of detection (LOD) was estimated to be 54 equivalent copies/reaction. An international standard for NiV is yet to be established, making it difficult to compare the sensitivity of the different methods. Serological assays are for the most part used in seroprevalence studies owing to their lower sensitivity in acute infection. Due to the high epidemic and pandemic potential of this virus, the diagnosis of NiV should be included in a more global One Health approach to improve surveillance and preparedness for the benefit of public health. Some steps need to be conducted in the diagnostic field in order to become more efficient in epidemic management, such as development of point-of-care (PoC) assays for the rapid diagnosis of NiV.

Global Burden of Lumpy Skin Disease, Outbreaks, and Future Challenges

Lumpy skin disease (LSD), a current global concern, causes economic devastation in livestock industries, with cattle and water buffalo reported to have higher morbidity and lower mortality rates. LSD is caused by lumpy skin disease virus (LSDV), a member of the Poxviridae family. It is an enzootic, rapidly explorative and sometimes fatal infection, characterized by multiple raised nodules on the skin of infected animals. It was first reported in Zambia in 1929 and is considered endemic in Africa south of the Sahara desert. It has gradually spread beyond Africa into the Middle East, with periodic occurrences in Asian and East European countries. Recently, it has been spreading in most Asian countries including far East Asia and threatens incursion to LSD-free countries. Rapid and accurate diagnostic capabilities, virus identification, vaccine development, vector control, regional and international collaborations and effective biosecurity policies are important for the control, prevention, and eradication of LSD infections. This review critically evaluates the global burden of LSD, the chronological historical outbreaks of LSD, and future directions for collaborative global actions.

Antimicrobial Resistance of Campylobacter coli Isolated from Caecal Samples of Fattening Pigs at Slaughter

Pigs are known as the main Campylobacter coli reservoirs. Campylobacteriosis, the most commonly reported gastrointestinal disease in humans, is mainly caused by the consumption of poultry meat, and little is known about the role of pork. Pigs are often associated with C. coli, including antimicrobial-resistant isolates. Therefore, the entire pork production chain must be considered as an important source of antimicrobial-resistant C. coli. This study aimed to determine the antimicrobial resistance of Campylobacter spp. isolated from caecal samples of fattening pigs at the Estonian slaughterhouse level over a five-year period. The proportion of Campylobacter-positive caecal samples was 52%. All Campylobacter isolates were identified as C. coli. A high proportion of the isolates were resistant to most of the studied antimicrobials. The resistance to streptomycin, tetracycline, ciprofloxacin and nalidixic acid was 74.8%, 54.4%, 34.4% and 31.9%, respectively. In addition, a high proportion (15.1%) of the isolates were multidrug-resistant and, in total, 93.3% were resistant to at least one antimicrobial.

Access to vaccination services for priority ruminant livestock diseases in Ghana: Barriers and determinants of service utilization by farmers

INTRODUCTION

Livestock diseases are a major constraint to agricultural productivity, frequently causing significant livelihood losses for farmers, and negatively affecting public food safety and security. Vaccines provide an effective and profitable means for controlling most infectious livestock diseases, but remain underutilized. This study sought to assess the barriers and determinants of vaccination utilization for priority livestock diseases in Ghana.

METHODS

We conducted a mixed-method study involving a quantitative survey with ruminant livestock farmers (N = 350) and seven focus group discussions (FGD) involving 65 ruminant livestock farmers. The survey data were analyzed, and distribution of barriers to vaccination access described. We evaluated the determinants of vaccination utilization (any use of vaccination against contagious-bovine-pleuropneumonia (CBPP) and peste-des-petits-ruminants (PPR) in 2021) using logistic regression analyses at the 0.05 significance level. FGD transcripts were analyzed deductively. We used triangulation to achieve convergence across the different datasets and analyses.

RESULTS

The farmers kept an average (median) of 5 tropical livestock units (TLUs) of ruminant livestock (IQR=2.6-12.0) that were on average 8 kilometers (IQR=1.9-12.4) away from veterinary officers (VOs). Only 16% (56/350) of herds were vaccinated against the diseases. Most farmers (274/350) had limited knowledge on vaccines against CBPP and PPR infections, 63% (222/350) perceived low risk of these diseases to their herds. About half of farmers reported experiencing outbreaks of either disease in the study year (2021). Farmers scored on average 80.5 out of 98 (IQR=74-85) on the RS-14 resilience scale. After adjusting for farmers' livestock rearing experience, herd size, sex, wealth status, distance to VOs, previous disease outbreaks, and perceived risk of the diseases, vaccination utilization was negatively associated with limited knowledge (aOR=0.19, 95%CI=0.08-0.43), and positively associated with personal exposure to outbreaks in the study year (aOR=5.26, 95%CI=2.01-13.7) and increasing resilience (aOR=1.13, 95%CI=1.07-1.19). FGDs revealed farmer misconceptions about vaccines, costs of vaccines, and timely access to vaccines from VOs as additional barriers.

CONCLUSIONS

Acceptability, affordability, accessibility, and availability of vaccine services represent the main barriers to vaccines utilization by ruminant livestock farmers in Ghana. Given that limited knowledge regarding the value of vaccination and shortfalls in veterinary service supply are of central importance for both the demand and supply side, more collaboration between the different stakeholders in a transdisciplinary manner to effectively address the low vaccination utilization problem is needed.

Potential Mammalian Vector-Borne Diseases in Live and Wet Markets in Indonesia and Myanmar

Vector-borne diseases spread from wild animals and their associated ectoparasites to humans and domesticated animals. Wildlife markets are recognized as important areas where this transfer can take place. We assessed the potential for spreading vector-borne diseases in two live and wet markets in Myanmar (Mong La, on the Myanmar-China border) and Indonesia (Sukahaji in Bandung on the island of Java) by making an inventory of all live and freshly killed wild mammals for sale. For eight mammal families, we quantified the number of animals on offer, and we used a heatmap cluster analysis to map vector-borne diseases that these families may carry. In Myanmar, we observed large numbers of wild pigs and deer (potentially carrying West Nile and various encephalitis viruses) whereas in Indonesia we observed Old World fruit bats (potentially carrying Chikungunya and encephalitis viruses) and squirrels (potentially carrying West Nile and encephalitis viruses). The trade in Indonesia was dominated by live mammals offered for sale as pets, and only Old World fruit bats and squirrels traded for traditional Asian medicine were killed in the markets. The trade in Myanmar was more geared towards wild meat (e.g., wild pigs, deer, primates) and traditional Asian medicine (squirrels). The combined risks of vector-borne diseases spreading from traded animals to human health highlight the need for an integrated approach protecting public health, economic interests and biodiversity.

Technology Readiness Levels for vaccine and drug development in animal health: From discovery to life cycle management

Public research and innovation initiatives in animal health aim to deliver key knowledge, services and products that improve the control of animal infectious diseases and animal welfare to deliver on global challenges including public health threats, environmental concerns and food security. The Technology Readiness Level (TRL) is a popular innovation policy instrument to monitor the maturity of upcoming new technologies in publicly funded research projects. However, while general definition of the 9 levels on the TRL-scale enable uniform discussions of technical maturity across different types of technology, these definitions are very generic which hampers concrete interpretation and application. Here, we aligned innovation pipeline stages as used in the animal health industry for the development of new vaccines or drugs with the TRL scale, resulting in TRL for animal health (TRLAH). This more bespoke scale can help to rationally allocate funding for animal health research from basic to applied research, map innovation processes, monitor progress and develop realistic progress expectations across the time span of a research and innovation project. The TRLAH thus become an interesting instrument to enhance the translation of public research results into industrial and societal innovation and foster public-private partnerships in animal health.

Risk of Viral Infectious Diseases from Live Bats, Primates, Rodents and Carnivores for Sale in Indonesian Wildlife Markets

Southeast Asia is considered a global hotspot of emerging zoonotic diseases. There, wildlife is commonly traded under poor sanitary conditions in open markets; these markets have been considered 'the perfect storm' for zoonotic disease transmission. We assessed the potential of wildlife trade in spreading viral diseases by quantifying the number of wild animals of four mammalian orders (Rodentia, Chiroptera, Carnivora and Primates) on sale in 14 Indonesian wildlife markets and identifying zoonotic viruses potentially hosted by these animals. We constructed a network analysis to visualize the animals that are traded alongside each other that may carry similar viruses. We recorded 6725 wild animals of at least 15 species on sale. Cities and markets with larger human population and number of stalls, respectively, offered more individuals for sale. Eight out of 15 animal taxa recorded are hosts of 17 zoonotic virus species, nine of which can infect more than one species as a host. The network analysis showed that long-tailed macaque has the greatest potential for spreading viral diseases, since it is simultaneously the most traded species, sold in 13/14 markets, and a potential host for nine viruses. It is traded alongside pig-tailed macaques in three markets, with which it shares six viruses in common (Cowpox, Dengue, Hepatitis E, Herpes B, Simian foamy, and Simian retrovirus type D). Short-nosed fruit bats and large flying foxes are potential hosts of Nipah virus and are also sold in large quantities in 10/14 markets. This study highlights the need for better surveillance and sanitary conditions to avoid the negative health impacts of unregulated wildlife markets.