Parasites burden in peri-urban free-roaming pigs in Gert Sibande District Municipality, Mpumalanga Province, South Africa.

BACKGROUND: Parasite infections, unlike regulated animal diseases, do not often receive attention. In fact, parasites are major sources of financial losses in pig enterprises, particularly in subsistence and small-scale pig production systems. OBJECTIVE: To identify and quantify the prevalence of ecto- and endo-parasites among peri-urban free-roaming pigs (FRP) in Gert Sibande District Municipality (GSDM), Mpumalanga. METHODS: Pig owners were identified using the snowball sampling method since no sampling frame for FRP farmers exists. Stratified sampling was used to select pigs for sampling for ecto- and endo-parasites. A form was used to record the observations. Pairwise correlation analysis was performed using Stata 15.0. The SPSS V28.0 statistical package was used to perform the chi-square test (X2) to assess the distribution of parasites in different age groups. The prevalence of parasites was assessed in different age groups of pigs using multi-response crosstabs. Multivariate analysis of variance (MANOVA) was used to estimate the marginal mean of parasites according to municipality. Statistical significance was assessed at α ≤ 0.05. RESULTS: Over 90% (91.2%) of the pigs examined were infested with at least one parasite, including Haematopinus suis, Sarcoptes scabiei, Ascaris suum, Fasciola hepatica, Trichuris suis, Strongylids, Coccidia spp, Moniezia expansa, and Siphonaptera spp. The correlation between Ascaris suum and body condition was weak but statistically significant (r = 0.24; p < 0.05). CONCLUSION: Policy makers, animal researchers and veterinary services must focus on developing policies, risk communication and community engagement materials, which target pig farmers in peri-urban areas such as Gert Sibande District Municipality, Mpumalanga Province.

Evaluation of antimicrobial usage in companion animals at a Veterinary Teaching Hospital in Nigeria.

This study investigated various qualitative and quantitative indices of antimicrobial use (AMU) in companion animals (CAs) at a Veterinary Teaching Hospital (VTH-A) and its annex (VTH- B) from 2019 to 2021. For 694 documented animals, antimicrobial administrations (AADs) were 5, 278 times, of which 98.8% (5217) and 1.2% (61) were in dogs and cats respectively. At the VTH- A, oxytetracycline (1185 times, 22.5%) was mostly administered in dogs and metronidazole (26 times, 0.5%) in cats. Similarly, at VTH- B, oxytetracycline was administered 895 times (17.0%) in dogs while amoxicillin was given 7 times (0.1%) in cats. The prescription diversity (PD) was estimated at 0.73 and 0.82 in VTH-A and VTH-B respectively. The quantity of antimicrobials (AMs) used was 10.1 kg (A, 6.2 kg and B, 3.9 kg). Oxytetracycline administrations and quantity of metronidazole (P < 0.0001) were higher than other Active Ingredients (AIs). Furthermore, 16.5% of AIs were classified as Critically Important Antibiotics (CIA) with the highest priority, while enrofloxacin, ciprofloxacin, and azithromycin fell under the World Health Organisation (WHO) Watch group. The In-Depth Interview (IDI) indicated that the high frequency of oxytetracycline administrations was linked with being the first choice for blood parasite treatment by the clinicians at the hospital. The quantity of metronidazole used was perceived to be higher due to the clinicians' preference for the treatment of acute gastroenteritis, its wider dose range, and the frequency of administration (bi-daily). The study provides baseline data on AMU indices in CAs, for the development of antimicrobial stewardship (AMS) and communication training, and policy modifications to enhance antimicrobial therapy optimization in tertiary veterinary hospital care in Nigeria.

Assessing complexity and dynamics in epidemics: geographical barriers and facilitators of foot-and-mouth disease dissemination.

Introduction: Physical and non-physical processes that occur in nature may influence biological processes, such as dissemination of infectious diseases. However, such processes may be hard to detect when they are complex systems. Because complexity is a dynamic and non-linear interaction among numerous elements and structural levels in which specific effects are not necessarily linked to any one specific element, cause-effect connections are rarely or poorly observed. Methods: To test this hypothesis, the complex and dynamic properties of geo-biological data were explored with high-resolution epidemiological data collected in the 2001 Uruguayan foot-and-mouth disease (FMD) epizootic that mainly affected cattle. County-level data on cases, farm density, road density, river density, and the ratio of road (or river) length/county perimeter were analyzed with an open-ended procedure that identified geographical clustering in the first 11 epidemic weeks. Two questions were asked: (i) do geo-referenced epidemiologic data display complex properties? and (ii) can such properties facilitate or prevent disease dissemination? Results: Emergent patterns were detected when complex data structures were analyzed, which were not observed when variables were assessed individually. Complex properties-including data circularity-were demonstrated. The emergent patterns helped identify 11 counties as 'disseminators' or 'facilitators' (F) and 264 counties as 'barriers' (B) of epidemic spread. In the early epidemic phase, F and B counties differed in terms of road density and FMD case density. Focusing on non-biological, geographical data, a second analysis indicated that complex relationships may identify B-like counties even before epidemics occur. Discussion: Geographical barriers and/or promoters of disease dispersal may precede the introduction of emerging pathogens. If corroborated, the analysis of geo-referenced complexity may support anticipatory epidemiological policies.

Seroepidemiology of Leptospira infection in slaughtered cattle in Gauteng province, South Africa.

Leptospirosis is an important economical disease of livestock globally, especially in Asia, the Caribbean, and the African continent. Its presence has been reported in a wide range of livestock. However, information on leptospirosis in South Africa is scanty. We conducted a cross-sectional study in 11 randomly selected abattoirs to determine the seroprevalence and risk factors for leptospirosis in slaughtered cattle in Gauteng province, South Africa. During abattoir visits to selected abattoirs, blood samples were collected from 199 cattle and demographic data obtained on the slaughtered animals. The microscopic agglutination test (MAT) was performed on all sera using a 26-serotype panel using cutoff titer ≥ 1:100. Animal- and abattoir-level risk factors were investigated for their association with seropositivity for leptospirosis. The seroprevalence of leptospirosis in the cattle sampled was 27.6% (55/199). The predominant serogroups detected in seropositive cattle were Sejroe (sv. Hardjo) (38.2%) and Mini sv. Szwajizak) (14.5%) but low to Canicola (sv. Canicola) (1.8%) and Pomona (sv. Pomona) (1.8%). The differences were statistically significant (P < 0.05). Of the five variables investigated, only one (abattoirs) had statistically significantly (P < 0.001) differences in the seroprevalence of leptospirosis among abattoirs. The study documented for the first time in South Africa, the occurrence of serogroups Sejroe (Hardjo bovis strain lely 607), Tarassovi, Hebdomadis, and Medanensis in slaughtered cattle. It was concluded that six of the nine serovars (representing seven serogroups) of Leptospira spp. circulating in cattle population in South Africa are not vaccine serogroups. The clinical, diagnostic, and public health importance of the findings cannot be ignored.

Expanding beyond zoonoses: the benefits of a national One Health coordination mechanism to address antimicrobial resistance and other shared health threats at the human-animal-environment interface in Kenya.

In order to manage global and transnational health threats at the human- animal-environment interface, a multisectoral One Health approach is required. Threats of this nature that require a One Health approach include, but are not limited to, emerging, endemic and re-emerging zoonotic diseases, food safety, antimicrobial resistance (AMR), vector-borne and neglected infectious diseases, toxicosis and pesticides. Relevant Kenyan authorities formally institutionalised One Health in 2011 through the establishment of the Zoonotic Disease Unit (ZDU) and its advisory group, the Zoonoses Technical Group. At that time, the One Health agenda focused on zoonotic diseases. As the issue of AMR began to gain traction globally, a One Health approach to its management was advocated in Kenya in 2015. This paper summarises a series of interviews (with respondents and key informants) that describe how AMR institutionalisation evolved in Kenya. It also examines how responses to other health threats at the human-animal- environment interface were coordinated and used to identify gaps and make recommendations to improve One Health coordination at the national level in Kenya. Results showed that the road to the institutionalisation of AMR through the National Action Plan on Prevention and Containment of Antimicrobial Resistance, 2017-2022 and a formally launched One Health coordination mechanism, the National Antimicrobial Stewardship Interagency Committee (NASIC), took ten years. Moreover, supplementary actions are still needed to further strengthen AMR coordination. In addition to the ZDU and NASIC, Kenya has established two other formal multisectoral and multidisciplinary coordination structures, one for aflatoxicosis and the other for health threats associated with pesticide use. The country has four distinct and separate One Health coordination mechanisms: for zoonoses, for AMR, for aflatoxicosis and for the health threats associated with pesticide use. The main gap lies in the lack of overall coordination between these topic-specific structures. An overall coordination mechanism for all One Health issues is therefore needed to improve synergy and complementarity. None of the topic-specific mechanisms plays a critical role in the policy development process, institutionalisation or implementation of activities related to the other topic areas. The authors recommend renaming the ZDU as the One Health Office, and expanding it to include AMR and food safety teams, and their associated technical working groups. Through this restructuring, the One Health Office would become an umbrella organisation dealing with all four issues mentioned above. Based on Kenya's experience, the authors recommend that other countries also consider expanding the scope of multisectoral One Health coordination mechanisms to include other shared health threats.

La gestion des menaces sanitaires mondiales et transnationales à l'interface homme­animal­environnement nécessite de faire appel à une approche Une seule santé multisectorielle. Les menaces de cette nature appelant une approche Une seule santé sont notamment (mais ne s'y limitent pas) les maladies zoonotiques émergentes, endémiques et réémergentes, la sécurité sanitaire des aliments, la résistance aux agents antimicrobiens, les maladies à transmission vectorielle, les maladies infectieuses négligées, les toxicoses et les pesticides. Les autorités kényanes ont institutionnalisé formellement l'approche Une seule santé en 2011 en mettant en place l'Unité Maladies zoonotiques (ZDU : Zoonotic Disease Unit) et son groupe consultatif, le Groupe technique Zoonoses. Le programme d'activités Une seule santé était alors centré sur les maladies zoonotiques. La problématique de l'antibiorésistance ayant gagné du terrain à l'échelle mondiale, en 2015 il a été préconisé de recourir à l'approche Une seule santé pour y faire face au Kenya. Les auteurs résument une série d'entretiens conduits auprès d'interlocuteurs et d'acteurs clés concernant l'évolution de l'institutionnalisation de la lutte contre la résistance aux agents antimicrobiens au Kenya. Ils mettent également en lumière le déroulement de la coordination des réponses mises en place pour contrer d'autres menaces sanitaires à l'interface homme­animal­environnement et l'éclairage que ces réponses ont permis d'apporter afin d'identifier les lacunes et de formuler des recommandations pour améliorer la coordination Une seule santé à l'échelle nationale. Il ressort de cette analyse qu'il a fallu dix ans pour que le Kenya institutionnalise le domaine de l'antibiorésistance à travers le Plan d'action national pour la prévention et la maîtrise de l'antibiorésistance (2017­2022) et pour qu'il mette en place un mécanisme officiel de coordination Une seule santé, le Comité national inter-agences de gestion concertée des agents antimicrobiens (NASIC : National Antimicrobial Stewardship Interagency Committee). Il est également apparu que des mesures complémentaires devaient être prises pour renforcer la coordination en matière d'antibiorésistance. Outre le ZDU et le NASIC, deux autres structures officielles de coordination multidisciplinaires et multisectorielles ont été créées au Kenya, chargées respectivement de l'aflatoxicose et des menaces sanitaires en lien avec l'utilisation de pesticides. Le pays dispose donc de quatre mécanismes de coordination distincts portant respectivement sur les zoonoses, l'antibiorésistance, l'aflatoxicose et les menaces sanitaires liées à l'utilisation de pesticides. La faille centrale est l'absence de coordination d'ensemble entre ces structures thématiques. Il faut donc instituer un mécanisme de coordination général pour toutes les questions relevant de l'approche Une seule santé, afin d'améliorer les synergies et la complémentarité. Aucun des mécanismes thématiques ne joue de rôle déterminant dans le processus d'élaboration des politiques, l'institutionnalisation ou la mise en œuvre de mesures relevant des autres thématiques. Les auteurs recommandent de modifier le nom du ZDU en Bureau Une seule santé et d'en élargir les compétences pour intégrer les équipes chargées de l'antibiorésistance et de la sécurité sanitaire des aliments ainsi que leurs groupes de travail techniques respectifs. Suite à cette restructuration, le Bureau Une seule santé pourrait devenir l'organisation transversale traitant des quatre thèmes précités. En se basant sur l'expérience du Kenya, les auteurs recommandent que d'autres pays s'engagent à leur tour sur la voie d'un élargissement de la portée des mécanismes de coordination multisectoriels Une seule santé afin d'inclure d'autres menaces sanitaires communes.

Para lidiar con las amenazas sanitarias mundiales o transnacionales en la interfaz de personas, animales y medio ambiente es preciso trabajar desde la óptica multisectorial de Una sola salud. Este tipo de amenazas que apelan al concepto de Una sola salud son, entre otras, las enfermedades zoonóticas emergentes, endémicas o reemergentes, los factores que afectan a la inocuidad de los alimentos, las resistencias a los antimicrobianos, las enfermedades infecciosas de transmisión vectorial o desatendidas, las toxicosis y los efectos del uso de plaguicidas. En 2011, con la creación de la ZDU (Zoonotic Disease Unit: unidad de enfermedades zoonóticas) y de un grupo técnico sobre zoonosis encargado de asesorarla, las autoridades competentes kenianas pusieron en práctica oficialmente la noción de Una sola salud. En aquel momento los programas de Una sola salud se centraban sobre todo en las enfermedades zoonóticas. A partir de 2015, cuando las resistencias a los antimicrobianos empezaron a ganar terreno en todo el mundo, en Kenia se apostó por combatirlas desde la óptica de Una sola salud. Los autores, sintetizando la información obtenida con una serie de encuestas y entrevistas con informadores clave, describen la progresiva institucionalización en Kenia de la lucha contra esas resistencias. También explican cómo se coordinaron las actividades de respuesta a otras amenazas sanitarias surgidas en la interfaz de personas, animales y medio ambiente y cómo ello sirvió para detectar deficiencias y formular recomendaciones encaminadas a mejorar la coordinación en clave de Una sola salud en todo el territorio nacional. Los resultados demuestran que hicieron falta diez años para institucionalizar la lucha contra la resistencia a los antimicrobianos, materializada en un plan nacional de acción sobre prevención y contención de antibiorresistencias para 2017­2022 y en la creación oficial de un mecanismo de coordinación de Una sola salud, el NASIC (National Antimicrobial Stewardship Interagency Committee: comité nacional interinstitucional de gestión de antimicrobianos). No obstante, aún hacen falta más medidas para mejorar la coordinación en todo lo relativo a las antibiorresistencias. Además de la ZDU y el NASIC, Kenia ha creado otras dos estructuras oficiales de coordinación multisectorial y multidisciplinar, una para la aflatoxicosis y otra para las amenazas sanitarias derivadas del uso de plaguicidas. El país cuenta así con cuatro mecanismos distintos e independientes de coordinación en clave de Una sola salud, centrados en las zoonosis, las antibiorresistencias, la aflatoxicosis y los riesgos sanitarios ligados a los plaguicidas. La principal deficiencia estriba en la falta de coordinación global entre estas estructuras de carácter temático. Para lograr mayores cotas de sinergia y complementariedad, por lo tanto, se requiere un mecanismo de coordinación general de todos los ámbitos de trabajo que tocan a la noción de Una sola salud. Ninguno de los mecanismos temáticos cumple una función decisiva en el proceso de formulación de políticas o de institucionalización y ejecución de actividades relacionadas con los demás ámbitos temáticos. Los autores recomiendan que la ZDU pase a denominarse Oficina de Una sola salud y que sea ampliada para integrar en ella a los equipos encargados de las antibiorresistencias y la inocuidad de los alimentos y a los correspondientes grupos de trabajo técnicos. Con semejante reestructuración, la Oficina de Una sola salud pasaría a ser una supraentidad que abarcaría los cuatro temas ya mencionados. Teniendo en cuenta la experiencia de Kenia, los autores recomiendan que otros países se planteen también la posibilidad de ampliar la cobertura de los mecanismos de coordinación multisectorial de Una sola salud para que incluyan otras amenazas sanitarias que tengan elementos en común.

The African swine fever epidemic in West Africa, 1996-2002.

African swine fever (ASF) is a contagious, highly fatal, haemorrhagic viral disease that only affects members of the Suidae family. Currently, no vaccine or treatment exists, so the disease has potentially devastating consequences for the pig industries, availability of affordable protein livelihoods and trade. This study aimed to consolidate historical information generated by working towards the control and eradication of ASF in previously unaffected countries in West Africa during 1996-2002. This descriptive analysis entailed the evaluation and review of archived records and reports of outbreaks, data from veterinary services, veterinary consultants and peer-reviewed publications. Specifically, the analysis focused on establishing the sequence of events in the spread of the disease throughout the region, as well as the possible sources and pathways (mostly human-driven, i.e., movement of pigs and swill feeding). The socio-economic aspects of the epidemic were also assessed. Finally, the prevention and control measures applied were described and evaluated. Major challenges for control that were identified involved lack of capacity to respond to an outbreak of animal disease and the nature of the pig sector in the affected countries. Most of the pigs were produced in low biosecurity subsistence husbandry systems. Actions taken by producers to limit economic losses due to the epidemic (e.g., illegal selling of pigs and infected pork, hiding of outbreaks) increased the risk of spread and frustrated control efforts. The disease has persisted in an endemic state ever since and has negatively affected pig production and marketing in most of these countries. The analysis of this information will allow a better understanding of the disease dynamics in a region infected for the first time, and learning how the prevention and control interventions that were implemented worked or failed. This will help the development of better tailored, sustainable and locally sound interventions. The authors provide a set of recommendations for ASF prevention and control.

Avian Influenza H5N1 Surveillance and its Dynamics in Poultry in Live Bird Markets, Egypt.

H5N1, a highly pathogenic avian influenza (H5N1 HPAI), is an endemic disease that is significant for public health in Egypt. Live bird markets (LBMs) are widespread in Egypt and play an important role in HPAI disease dynamics. The aim of the study was to evaluate the H5N1 HPAI prevalence in representative LBMs from 2009 to 2014, assess the effects of other variables and evaluate past outbreaks and human cases. It was found that ducks and geese are high-risk species and that the prevalence of H5N1 HPAI was higher immediately after the political crises of 2011. The end of a calendar year (June to December) was a high-risk period for positive samples, and the risk in urban LBMs was twice the risk in rural LBMs. Winter and political unrest was associated with higher H5N1 HPAI prevalence. Both human and poultry populations will continue to rise in Egypt, so continued poultry outbreaks are likely to be linked to more human cases. LBMs will continue to play a role in the dynamics of poultry disease in Egypt, and there is a need to reorganize markets in terms of biosecurity and traceability. It may also be beneficial to reduce inter-governorate inter-regional movements associated with poultry trade through promotion of regional trade or in the alternative provide sanitary features along the poultry market chain to reduce the speed of H5N1 HPAI infections. Policy formulation, design and enforcement must be pro-poor, and consideration of the sociocultural and economic realities in Egypt is important. The LBMs provide ideal platforms to carry out sound surveillance plans and mitigate zoonotic risks of H5N1 HPAI to humans.

Development of Disease-specific, Context-specific Surveillance Models: Avian Influenza (H5N1)-Related Risks and Behaviours in African Countries.

Avian influenza virus (H5N1) is a rapidly disseminating infection that affects poultry and, potentially, humans. Because the avian virus has already adapted to several mammalian species, decreasing the rate of avian-mammalian contacts is critical to diminish the chances of a total adaptation of H5N1 to humans. To prevent the pandemic such adaptation could facilitate, a biology-specific disease surveillance model is needed, which should also consider geographical and socio-cultural factors. Here, we conceptualized a surveillance model meant to capture H5N1-related biological and cultural aspects, which included food processing, trade and cooking-related practices, as well as incentives (or disincentives) for desirable behaviours. This proof of concept was tested with data collected from 378 Egyptian and Nigerian sites (local [backyard] producers/live bird markets/village abattoirs/commercial abattoirs and veterinary agencies). Findings revealed numerous opportunities for pathogens to disseminate, as well as lack of incentives to adopt preventive measures, and factors that promoted epidemic dissemination. Supporting such observations, the estimated risk for H5N1-related human mortality was higher than previously reported. The need for multidimensional disease surveillance models, which may detect risks at higher levels than models that only measure one factor or outcome, was supported. To develop efficient surveillance systems, interactions should be captured, which include but exceed biological factors. This low-cost and easily implementable model, if conducted over time, may identify focal instances where tailored policies may diminish both endemicity and the total adaptation of H5N1 to the human species.

Transmission dynamics and control of Ebola virus disease outbreak in Nigeria, July to September 2014.

We analyse up-to-date epidemiological data of the Ebola virus disease outbreak in Nigeria as of 1 October 2014 in order to estimate the case fatality rate, the proportion of healthcare workers infected and the transmission tree. We also model the impact of control interventions on the size of the epidemic. Results indicate that Nigeria's quick and forceful implementation of control interventions was determinant in controlling the outbreak rapidly and avoiding a far worse scenario in this country.

Drivers and risk factors for circulating African swine fever virus in Uganda, 2012-2013.

We explored observed risk factors and drivers of infection possibly associated with African swine fever (ASF) epidemiology in Uganda. Representative sub-populations of pig farms and statistics were used in a case-control model. Indiscriminate disposal of pig viscera and waste materials after slaughter, including on open refuse dumps, farm-gate buyers collecting pigs and pig products from within a farm, and retention of survivor pigs were plausible risk factors. Wire mesh-protected windows in pig houses were found to be protective against ASF infection. Sighting engorged ticks on pigs, the presence of a lock for each pig pen and/or a gate at the farm entrance were significantly associated with infection/non-infection; possible explanations were offered. Strict adherence to planned within-farm and community-based biosecurity, and avoidance of identified risk factors is recommended to reduce infection. Training for small-scale and emerging farmers should involve multidimensional and multidisciplinary approaches to reduce human-related risky behaviours driving infection.

Comparative evaluation of novel African swine fever virus (ASF) antibody detection techniques derived from specific ASF viral genotypes with the OIE internationally prescribed serological tests.

The presence of antibodies against African swine fever (ASF), a complex fatal notifiable OIE disease of swine, is always indicative of previous infection, since there is no vaccine that is currently used in the field. The early appearance and subsequent long-term persistence of antibodies combined with cost-effectiveness make antibody detection techniques essential in control programmes. Recent reports appear to indicate that the serological tests recommended by the OIE for ASF monitoring are much less effective in East and Southern Africa where viral genetic and antigenic diversity is the greatest. We report herein an extensive analysis including more than 1000 field and experimental infection sera, in which the OIE recommended tests are compared with antigen-specific ELISAs and immuno-peroxidase staining of cells (IPT). The antibody detection results generated using new antigen-specific tests, developed in this study, which are based on production of antigen fractions generated by infection and virus purification from COS-1 cells, showed strong concordance with the OIE tests. We therefore conclude that the lack of success is not attributable to antigenic polymorphism and may be related to the specific characteristics of the local breeds African pigs.

Molecular diagnosis of African Swine Fever by a new real-time PCR using universal probe library.

A highly sensitive and specific real-time PCR method was developed for the reliable and rapid detection of African swine fever virus (ASFV). The method uses a commercial Universal Probe Library (UPL) probe combined with a specifically designed primer set to amplify an ASFV DNA fragment within the VP72 coding genome region. The detection range of the optimized UPL PCR technique was confirmed by analysis of a large panel (n = 46) of ASFV isolates, belonging to 19 of the 22 viral p72 genotypes described. No amplification signal was observed when closely clinically related viruses, such as classical swine fever, or other porcine pathogens were tested by this assay. The detection limit of the UPL PCR method was established below 18 DNA copies. Validation experiments using an extensive collection of field porcine and tick samples (n = 260), coming from Eastern and Western African regions affected by ASF, demonstrated that the UPL PCR technique was able to detect over 10% more positive samples than the real-time TaqMan PCR test recommended in the OIE manual, confirming its superior diagnostic sensitivity. Clinical material collected during experimental infections with different ASFV p72 genotypes was useful for assuring both the capacity of the UPL PCR for an early viral DNA detection and the competence of the technique to be applied in any ASF diagnostic target sample. The reliability and robustness of the UPL PCR was finally verified with a panel of ASFV-infected clinical samples which was repeatedly tested at different times. Additionally, an internal control PCR assay was also developed and standardized using UPL probes within the endogenous ß-actin gene. Finally, the complete study offers a new validated real-time PCR technique, by means of a standardized commercial probe, providing a simple, rapid and affordable test, which is ready for application in the routine diagnosis of ASF.

Risk factors for farm-level African swine fever infection in major pig-producing areas in Nigeria, 1997-2011.

African swine fever (ASF) is an economically devastating disease for the pig industry, especially in Africa. Identifying what supports infection on pig farms in this region remains the key component in developing a risk-based approach to understanding the epidemiology of ASF and controlling the disease. Nigeria was used for this matched case-control study, because there is perpetual infection in some areas, while contiguous areas are intermittently infected. Risk factors and biosecurity practices in pig farms were evaluated in association with ASF infection. Subsets of farms located in high-density pig population areas and high-risk areas for ASF infection were randomly selected for analysis. Most plausible risk factor variables from the univariable analysis included in the multivariable analysis include: owner of farm had regular contact with infected farms and other farmers, untested pigs were routinely purchased into the farm in the course of outbreaks, there was an infected neighbourhood, other livestock were kept alongside pigs, there was a presence of an abattoir/slaughter slab in pig communities, wild birds had free access to pig pens, tools and implements were routinely shared by pig farmers, there was free access to feed stores by rats, and feed was purchased from a commercial source. Only the presence of an abattoir in a pig farming community (OR=8.20; CI(95%)=2.73, 24.63; P<0.001) and the presence of an infected pig farm in the neighbourhood (OR=3.26; CI(95%)=1.20, 8.83; P=0.02) were significant. There was a marginally significant negative association (protective) between risk of ASF infection and sharing farm tools and equipment (OR=0.35; CI(95%)=0.12, 1.01; P=0.05). Of the 28 biosecurity measures evaluated, food and water control (OR=0.14; CI(95%)=0.04, 0.46; P<0.001), separation/isolation of sick pigs (OR=0.14; CI(95%)=0.04, 0.53; P=0.004) and washing and disinfection of farm equipment and tools (OR=0.27; CI(95%)=0.10, 0.78; P=0.02) were negatively associated (protective) with ASF infection. Consultation and visits by veterinarian/paraveterinarians when animals were sick (OR=8.11; CI(95%)=2.13, 30.90; P=0.002), and pest and rodent control were positively associated with ASF infection of Nigerian farms (OR=4.94; CI(95%)=1.84, 13.29; P=0.002). The presentation of sick and unthrifty pigs for slaughter at abattoirs, farmers' inadvertent role, an infected neighbourhood, a pig to pig contact, rodents and wild birds may contribute to infections of farms, whereas washing, disinfection of tools, food and water control, and separation of sick pigs reduces the likelihood of infections. Underlying reasons for these observations and strategies for control are discussed.

Epidemic protection zones: centred on cases or based on connectivity?

When an exotic infectious disease invades a susceptible environment, protection zones are enforced. Historically, such zones have been shaped as circles of equal radius (ER), centred on the location of infected premises. Because the ER policy seems to assume that epidemic dissemination is driven by a similar number of secondary cases generated per primary case, it does not consider whether local features, such as connectivity, influence epidemic dispersal. Here we explored the efficacy of ER protection zones. By generating a geographically explicit scenario that mimicked an actual epidemic, we created protection zones of different geometry, comparing the cost-benefit estimates of ER protection zones to a set of alternatives, which considered a pre-existing connecting network (CN) - the road network. The hypothesis of similar number of cases per ER circle was not substantiated: the number of units at risk per circle differed up to four times among ER circles. Findings also showed that even a small area (of <115 km(2) ) revealed network properties. Because the CN policy required 20% less area to be protected than the ER policy, and the CN-based protection zone included a 23.8% greater density of units at risk/km(2) than the ER-based alternative, findings supported the view that protection zones are likely to be less costly and more effective if they consider connecting structures, such as road, railroad and/or river networks. The analysis of local geographical factors (contacts, vectors and connectivity) may optimize the efficacy of control measures against epidemics.

The cost-benefit of biosecurity measures on infectious diseases in the Egyptian household poultry.

Increased animal intensification presents with increasing risks of animal diseases. The Egyptian household poultry is peculiar in its management style and housing and this present with particular challenges of risk of infection to both the flock and humans. Biosecurity remains one of the most important means of reducing risks of infection in the household poultry, however not much information is available to support its feasibility at the household level of production. In this study financial feasibilities of biosecurity were modeled and evaluated based on certain production parameters. Risks of particular importance to the household poultry were categorized and highly pathogenic avian influenza H5N1 was the most risky disease while people-related risk was the most important risk category. It was observed that basic biosecurity measures were applicable in the household poultry and it would be 8.45 times better to implement biosecurity than to do nothing against HPAI H5N1; 4.88 times better against Newcastle disease and 1.49 times better against coccidiosis. Sensitivity analyses proved that the household poultry project was robust and would withstand various uncertainties. An uptake pathway for basic biosecurity was suggested. The outcome of this work should support decisions to implement biosecurity at the household sector of poultry production.

Cost implications of African swine fever in smallholder farrow-to-finish units: economic benefits of disease prevention through biosecurity.

African swine fever remains the greatest limitation to the development of the pig industry in Africa, and parts of Asia and Europe. It is especially important in West and Central African countries where the disease has become endemic. Biosecurity is the implementation of a set of measures that reduce the risk of infection through segregation, cleaning and disinfection. Using a 122-sow piggery unit, a financial model and costing were used to estimate the economic benefits of effective biosecurity against African swine fever. The outcomes suggest that pig production is a profitable venture that can generate a profit of approximately US$109,637.40 per annum and that an outbreak of African swine fever (ASF) has the potential to cause losses of up to US$910,836.70 in a single year. The implementation of biosecurity and its effective monitoring can prevent losses owing to ASF and is calculated to give a benefit-cost ratio of 29. A full implementation of biosecurity will result in a 9.70% reduction in total annual profit, but is justified in view of the substantial costs incurred in the event of an ASF outbreak. Biosecurity implementation is robust and capable of withstanding changes in input costs including moderate feed price increases, higher management costs and marginal reductions in total outputs. It is concluded that biosecurity is a key to successful pig production in an endemic situation.

Surveillance for African swine fever in Nigeria, 2006-2009.

African swine fever (ASF) has had significant economic and social impact in Nigeria since 1997. However, there has been no effective national response to bring it under control. In this report, we confirm that ASF is still prevalent and widespread in Nigeria. Results from both serosurveillance and virological analyses indicated that ASF is present in most of the agro-ecological zones of the country. Nine per cent (9%) of serum samples and 48% of tissue samples were positive for ASF virus antibody and genome, respectively. Areas with high pig-related activities (marketing, consumption and farming) have higher prevalences compared with areas with less pig activities. Farm-gate buyers, marketing systems and transport of untested pigs within the country assist with the circulation of the virus. Only by putting in place a comprehensive routine surveillance and testing system, reorganizing the market and transportation systems for pigs, implementing on-farm bio-security protocols and considering the option of compensation will it be possible to achieve a significant reduction in ASF prevalence in Nigeria.

Avian influenza A(H5N1) in humans: lessons from Egypt.

Highly pathogenic avian influenza A(H5N1) has ravaged the Egyptian poultry population. Ninety human cases, including 27 fatalities have been recorded by 30 December, 2009. However, epidemiological information on the infection in humans in Egypt is scarce. We analysed the first three years of highly pathogenic avian influenza A(H5N1) in Egypt between 20 March 2006 and 31 August 2009) and found that more cases occurred in females than males, especially in 2006 and 2007. Women in the age group 20-39 years had the greatest tendency to be infected. It took an average of one day and 18 hours to seek medical assistance in patients who recovered and of six days in fatal cases. Children sought treatment much earlier than adults. On average, a patient died 11 days after the onset of symptoms. Exposure to infected poultry remained the most important risk factor.

Lessons from Nigeria: the role of roads in the geo-temporal progression of avian influenza (H5N1) virus.

The daily progression of the 2006 (January-June) Nigerian avian influenza (AI H5N1) epidemic was assessed in relation to both spatial variables and the generation interval of the invading virus. Proximity to the highway network appeared to promote epidemic dispersal: from the first AI generation interval onwards > 20% of all cases were located at < 5 km from the nearest major road. Fifty-seven per cent of all cases were located 31 km from three highway intersections. Findings suggest that the spatial features of emerging infections could be key in their control. When the spatial location of a transmission factor is well known, such as that of the highway network, and a substantial percentage of cases (e.g. > 20%) are near that factor, early interventions focusing on transmission factors, such as road blocks that prevent poultry trade, may be more efficacious than interventions applied only to the susceptible population.

Molecular characterization and epidemiology of the highly pathogenic avian influenza H5N1 in Nigeria.

Avian influenza caused infection and spread throughout Nigeria in 2006. Carcass samples (lung, liver, spleen, heart, trachea and intestine) from the different regions of Nigeria were processed for virus isolation. Infective allantoic fluids were tested for avian influenza viruses (AIV) and Newcastle disease virus using monospecific antisera. Thirty-five isolates were generated and characterized molecularly using the haemagglutinin gene. The molecular analysis indicated that different sublineages of the highly pathogenic avian influenza (HPAI) H5N1 viruses spread throughout Nigeria. We compared the Nigerian isolates with others from Africa and results indicated close similarities between isolates from West Africa and Sudan. Some of the analysed viruses showed genetic drift, and the implications of these for future epidemiology and ecology of avian influenza in Africa require further evaluation. The spread of primary outbreaks was strongly linked to trade (legal and illegal), live bird markets, inappropriate disposal, and poorly implemented control measures. No strong correlation existed between wild birds and HPAI H5N1 in Nigeria.