A review of pig and poultry diseases in the Eastern Cape Province of South Africa, 2000-2020.

ABSTRACT: The informal poultry and pig sector in the Eastern Cape Province (ECP) of South Africa is of significant socio-economic importance as it sustains livelihoods and ensures food security; yet little is known about the distribution and prevalence of infectious and zoonotic diseases in this region. This paper reviews data published for pig and poultry diseases in the province during the last 20 years (2000-2020). The review included relevant published papers identified by a computerised literature search from Web of Science; provincial animal health reports; the national database from the Department of Agriculture, Land Reform and Rural Development (DALRRD); animal health reports submitted by DALRRD to the World Organisation for Animal Health (OIE) via the World Animal Health Information Database (WAHID) interface and laboratory records. A publication was considered eligible if it included qualitative or quantitative information on any disease affecting pigs and poultry including zoonosis. The search retrieved 174 publications, of which 26 were relevant. The review found that Newcastle disease (ND), coccidiosis and fowl pox (FP) were the most reported avian diseases in the national database, whereas avian infectious bronchitis (AIB), ND and highly pathogenic avian influenza (HPAI) were the most reported diseases in the OIE database. Classical swine fever (CSF) was the most reported pig disease in both databases. The retrieved literature on pig and poultry diseases was scarce and no longer up to date, providing decision makers with little information. The review identified important zoonotic diseases that require further studies yet failed to find information on important neglected diseases like leptospirosis.

Using value chain and trade networks in the Eastern Cape Province of South Africa, as a basis for targeted rural chicken surveillance.

Despite the benefits of rural chickens in the Eastern Cape Province (ECP) of South Africa, this sector is still underdeveloped and poorly surveyed for poultry diseases. The lack of a sustainable poultry disease surveillance system coupled with communities and practices where the interactions between birds are high, emphasize the need for targeted surveillance of chicken diseases in the province. However, to set up such a system requires knowledge of the value chain and trade networks. Consequently, a survey, which involved a rural chicken value chain analysis that also included an assessment of trading practices to identify biosecurity hotspots and an identification of barriers to market entry for rural farmers was conducted. Secondly, a social network analysis of chicken movements in the province was carried out to identify trade hubs that could be targeted for disease surveillance based on their centrality within the network and their size and influence within their ego networks. Traders and their transport vehicles were identified as biosecurity hotspots that could be targeted for disease surveillance within the chain. Social network analysis identified three municipalities viz. Umzimvubu, King Sabata Dalindyebo (KSD) and Enoch Mgijima as trade hubs where interaction between rural chickens occurs and resources can be focused. The movement of spent hens from commercial operations that are transported over long distances and distributed in the rural areas and townships were a major risk for spread of poultry diseases. This is the first study to formally describe chicken trade networks within the province and the surrounding region. Its findings provide a model for cost effective targeted surveillance in the ECP and similar resource poor regions of the world. The study also provides insight into the profitability of rural chickens and a possible contribution to job creation and poverty alleviation once the barriers to market entry are lifted.

A study of rural chicken farmers, diseases and remedies in the Eastern Cape province of South Africa.

The source of emerging diseases and antimicrobial resistance is of increasing interest to epidemiologists. This paper looks at village chickens as such a source. In addition, infectious diseases constitute a major challenge to the growth and profitability of the rural poultry sector in Sub-Saharan Africa. A serological survey was conducted to estimate the apparent seroprevalence of selected chicken diseases in the Eastern Cape Province of South Africa alongside a sociological survey of poultry farmers and the remedies most commonly used to prevent diseases in their flocks. Sera collected from village chickens (n = 1007) in the province were screened for specific antibodies against Newcastle disease (ND), avian influenza (AI), avian infectious bronchitis (IB) and Mycoplasma gallisepticum (MG). The overall seroprevalence of ND, AI, IB and MG in the province was found to be 69.2 % (95 % CI 51.9-86.5%); 1.8 % (95 % CI 0.2-3.4%); 78.5 % (95 % CI 74.9-82%) and 55.8 % (95 % CI 41.3-70.3%) respectively with clustering found at the District level. Cross hemagglutination inhibition (HI) tests indicated that the chickens were exposed to the ND vaccine. AI ELISA-positive samples were tested using HIs against the H5, H6 and H7-subtypes, but only H6-specific antibodies were detected. Avian influenza strains shared the common ancestor responsible for the 2002 chicken outbreak in KwaZulu-Natal Province. The majority of chicken farmers were females and pensioners (69 % and 66.1 % respectively) and had a primary school education (47.1 %). Traditional remedies were commonly used by farmers (47.15 %) and among the remedies, Aloe plant (Aloe ferox Mill.) or ikhala (Xhosa) was the most commonly used product (28.23 %) for preventing and reducing mortalities among village chickens. The findings stress the importance of village chickens as a substitute for social welfare and highlight the exposure of village chickens to important chicken pathogens. The economic impact of these pathogens on the development of this sub-sector needs further investigation. Village chickens are a potential source of virulent Newcastle disease virus (NDV) because of the lack of vaccination and biosecurity. They may serve as amplification hosts which increases the probability that virulent NDV could spill over into commercial poultry flocks due to large amounts of circulating virus. The zoonotic threat of circulating H6N2 viruses raise concern due to their mutation and reassortment among chickens and a potential movement of infected birds within the province. Finally, the use of antibiotics by untrained chicken farmers constitute another major concern as it could serve as a source of antimicrobial resistance (AMR).

Analysing production and financial data from farmers can serve as a tool for identifying opportunities for enhancing extension delivery among the rural poultry sub-sector in Zambia.

There are limited data on production and financial performance of the rural poultry sector in developing countries like Zambia that could be used by extension services as a feedback loop to enhance service delivery in the sector. Thus, a study that used production and financial data obtained from poultry farmers of Eastern Zambia was conducted to describe the rural poultry sub-sector and conduct financial analysis. It compared the financial performance of indigenous chicken production to broiler and layer production. The aim of the study was to identify opportunities and knowledge gaps among poultry farmers that could be used to initiate and enhance a participatory extension approach and build capacity of farmers in the sector. Descriptive, spatial, gross margin and breakeven analysis was used to analyse data obtained from 459 rural poultry farmers and expert opinion from 5 local extension workers. Poultry ranked highest in terms of popularity and numbers when compared with other animals kept by respondents (median = 20). Most poultry were kept under free-range and brood an average of 3.1 clutches. Except for annual set up costs, some variable costs and household poultry consumption, the study could obtain data on most production costs and income generated from poultry farmers. Nevertheless, gross margin analysis conducted using costing data from poultry farmers and expert opinion of extension workers revealed that indigenous chicken enterprises had the highest gross margin percentage of 72% compared to commercial broilers and layers which had gross margin percentages of 53% and 56% respectively. Breakeven analysis revealed that indigenous chickens required the lowest number of products to be sold (27) to realise profit compared to broilers (1011) and layers (873). The study justifies investment into the rural poultry sub-sector and discusses the use of gross margin templates as a means of incentivising rural farmers to participate in extension programmes.

Is syndromic data from rural poultry farmers a viable poultry disease reporting tool and means of identifying likely farmer responses to poultry disease incursion?

Syndromic surveillance is a well described tool used in developed countries for alerting authorities to livestock disease incursions. However, little work has been done to evaluate whether this could be a viable tool in countries where disease reporting infrastructure and resources is poor. Consequently, a syndrome-based questionnaire study in Eastern Zambia was designed to gather data on previous encounters farmers had with poultry diseases, as well as control measures they use to mitigate them. Descriptive statistics and logistic regression were used to analyse the data. Farmers reported an overall annual disease incidence in rural poultry for eastern Zambia of 31% (90% CI 29-32%). Occurrence of poultry disease in the last 12 months was associated with use of middlemen to purchase poultry products (p = 0.05, OR = 7.87), poultry products sold or given away from the farm (p = 0.01, OR = 1.92), farmers experiencing a period with more trade of poultry and its products (p = 0.04, OR = 1.70), presence of wild birds near the farm or village (p = 0.00, OR = 2.47) and poultry diseases being reported from neighbouring farms or villages (p = 0.00, OR = 3.12). The study also tentatively identified three poultry diseases (Newcastle Disease, Gumboro Disease and Fowl Pox) from the thirty-four disease syndromes provided by farmers. Farmers reported an incidence of 27% for Newcastle Disease in 2014. When compared with the state veterinary services data which reported Newcastle Disease incidence at 9% in 2014, it seems syndromic data obtained from farmers may be more sensitive in identifying disease incursion. Thirty-six remedies and strategies farmers use to treat and control these diseases were revealed. The main control strategy for identified diseases was vaccination and the main treatment was unspecified herbs, which warrants further investigation and presents an opportunity for further research in ethno-veterinary medicine. More still, this study identified chilli, Aloe Vera, garlic onion, moringa, and ash as traditional remedies that are commonly being used in Eastern Zambia, and which are also used to treat poultry diseases in Zimbabwe and Botswana. Only fourteen remedies described are conventionally accepted by veterinarians as remedies and disease control measures for poultry diseases. This study shows that syndromic data obtained from farmers is a useful disease reporting tool and could be used as an effective means of alerting authorities to disease incursion. In addition, it shows that these data may give a more accurate estimate of incidence for certain diseases than current surveillance methods and could be useful in assessing significant risk factors associated with disease occurrence.

Tracing the origins of genotype VIIh Newcastle disease in southern Africa.

It is widely accepted that Newcastle disease is endemic in most African countries, but little attention has been afforded to establishing the sources and frequency of the introductions of exotic strains. Newcastle disease outbreaks have a high cost in Africa, particularly on rural livelihoods. Genotype VIIh emerged in South-East Asia and has since caused serious outbreaks in poultry in Malaysia, Indonesia, southern China, Vietnam and Cambodia. Genotype VIIh reached the African continent in 2011, with the first outbreaks reported in Mozambique. Here, we used a combination of phylogenetic evidence, molecular dating and epidemiological reports to trace the origins and spread of subgenotype VIIh Newcastle disease in southern Africa. We determined that the infection spread northwards through Mozambique, and then into the poultry of the north-eastern provinces of Zimbabwe. From Mozambique, it also reached neighbouring Malawi and Zambia. In Zimbabwe, the disease spread southward towards South Africa and Botswana, causing outbreaks in backyard chickens in early-to-mid 2013. In August 2013, the disease entered South Africa's large commercial industry, and the entire country was infected within a year, likely through fomites and the movements of cull chickens. Illegal poultry trading or infected waste from ships and not wild migratory birds was the likely source of the introduction to Mozambique in 2011.

A retrospective study and predictive modelling of Newcastle Disease trends among rural poultry of eastern Zambia.

Newcastle Disease (ND) is a highly infectious disease of poultry that seriously impacts on food security and livelihoods of livestock farmers and communities in tropical regions of the world. ND is a constant problem in the eastern province of Zambia which has more than 740 000 rural poultry. Very few studies give a situational analysis of the disease that can be used for disease control planning in the region. With this background in mind, a retrospective epidemiological study was conducted using Newcastle Disease data submitted to the eastern province headquarters for the period from 1989 to 2014. The study found that Newcastle Disease cases in eastern Zambia followed a seasonal and cyclic pattern with peaks in the hot dry season (Overall Seasonal Index 1.1) as well as cycles every three years with an estimated provincial incidence range of 0.16 to 1.7% per year. Annual trends were compared with major intervention policies implemented by the Zambian government, which often received donor support from the international community during the study period. Aid delivered through government programmes appeared to have no major impact on ND trends between 1989 and 2014 and reasons for this are discussed. There were apparent spatial shifts in districts with outbreaks over time which could be as a result of veterinary interventions chasing outbreaks rather than implementing uniform control. Data was also fitted to a predictive time series model for ND which could be used to plan for future ND control. Time series modelling showed an increasing trend in ND annual incidence over 25 years if existing interventions continue. A different approach to controlling the disease is needed if this trend is to be halted. Conversely, the positive trend may be a function of improved reporting by farmers as a result of more awareness of the disease.

The red cell 3 phosphoglycerate kinase polymorphism. Report of a new allele.

Blood samples from 778 Burundian, Rwandan, and Zairan negroes were examined by electrophoresis on cellulose acetate for phosphoglycerate kinase polymorphism. PGK 1 was observed in all but 6 hemolysates; in these cases a new allele was detected, having a frequency of about 0.018 in Rwandans.

[Determination of the phenotypes of several erythrocytic enzymes by cellulose acetate electrophoresis]. / Détermination des phénotypes de quelques enzymes érythrocytaires par électrophorèse sur acétate de cellulose

The authors describe simple and rapid separation technics by electrophoresis on cellulose acetate of glucose-6-phosphate dehydrogenase isoenzymes, 6-phosphogluconate dehydrogenase, phosphoglucomutase, adenosine deaminase, adenylate kinase, phosphohexose isomerase, lactate dehydrogenase iosenzymes in the red cells. These technics are derived from those of Rattazi et al. for glucose-6-phosphate dehydrogenase and Sonneborn for 6-phosphogluconate dehycrogenase, phosphoglucomutase, adenosine deaminase, adenylate kinase and acid phosphatase.