Newcastle disease in family poultry: prospects for its control through ethnoveterinary medicine

E F Guèye

Senegalese Institute of Agricultural Research (ISRA),
BP 2057, Dakar-Hann, Senegal,
efgueye@refer.sn
(Paper presented at the 27th World Veterinary Congress, 25-29 September 2002, Tunis, Tunisia)

Abstract

Family poultry (FP) are still very important in low-income food-deficit countries (LIFDCs). However, the high incidence of diseases is one of the major constraints to smallholder poultry production systems. Newcastle disease, the most serious epizootic poultry disease in most LIFDCs, occurs every year and kills on average 70 to 80% of the unvaccinated rural family poultry flocks. Ethnoveterinary medicine is widely used by resource-poor FP-keeping farmers, especially women. Natural products, especially plant products that are locally available, are generally used. Although FP-keeping farmers claim that these practices are effective, there is an urgent need for applied research to substantiate their findings.

Keywords: Ethnoveterinary medicine, family poultry, low-income food-deficit country, Newcastle disease, plants

Introduction

The growth of the world human population, which is expected to increase from 5,282 million in 1990 to 7,286 million in the year 2015 (Anonymous 1999), will take place largely in low-income food-deficit countries (LIFDCs) of Africa, Asia, the Near East, Latin America, Europe and the South Pacific. LIFDCs are defined by the Food and Agriculture Organization of the United Nations (FAO) (http://www.fao.org/) as nations that are poor, with mean net income per person amounting to less that US$ 1,505 per annum, and are net importers of food. In 1998, 83 nations were defined as LIFDCs (42 in Africa, 24 in Asia, 7 in Latin America and the Caribbean, 7 in Oceania and 3 in Europe). Most of the 826 million people still suffering from malnutrition, and approximately 1.2 billion people living on less than US$ 1 a day (Anonymous 2001) live in LIFDCs, especially in the arid zones of Africa and Asia. Family poultry (FP) are still very important in LIFDCs (Branckaert and Guèye 2000; Guèye 2000). Through using available natural resources efficiently, FP constitute an important component of the agricultural and household economy in LIFDCs, a contribution that goes beyond direct food production for the fast growing human population as well as employment and income generation for resource-poor small farmers, especially women (Guèye 2002a). They also serve as a means of capital accumulation and as a barter product in societies where there is no circulation of currency. Furthermore, they are closely linked to the religious and socio-cultural lives of several million resource-poor farmers for whom poultry ownership ensures varying degrees of sustainable farming and economic stability. Additionally FP have medicinal and environmental functions. Therefore, the overall contribution provided by FP at household, community and country levels is generally underestimated since the multitude of roles played by poultry in LIFDCs are generally ignored, in part because they are extremely difficult to assess (Guèye 2002b).

FP poultry production systems which are practised in LIFDCs have been previously described by various workers (Bessei 1987; Aini 1990; Guèye and Bessei 1996; Kitalyi 1998; Branckaert and Guèye 2000; Guèye 1998 2002a, 2002b; Guèye and van’t Hooft 2002). Birds, kept under these husbandry systems are subject to high mortality resulting from accidents, predation or diseases. Newcastle disease (ND) is one of the worst enemies of FP. Ethnoveterinary medicine (EVM) is widely used by FP-keeping farmers in LIFDCs to control this disease. Only ethnoveterinary practices that are considered by FP-keeping farmers as being common and effective are highlighted. Although poultry keepers claim that EVM is effective, there is still a need to conduct experiments under controlled conditions in order to test these traditional remedies.

Newcastle disease – a world challenge

ND or Ranikhet disease or avian pneumoencephalitis or pseudo fowl pest constitutes the most serious epizootic poultry disease throughout the world, particularly in LIFDCs (Chu and Rizk 1972; Aini 1990; Demey 1990; Spradbrow 1994, 1996; Bell 1996; Guèye 1998 2002b; Branckaert and Guèye 2000). It is a highly contagious disease of the respiratory and nervous systems, mostly affecting chickens, but sometimes also affecting other poultry species, such as guinea fowls, ducks, turkeys, etc. It often devastates unvaccinated FP flocks in periodic outbreaks. The disease is caused by a paramyxovirus, with the most virulent strains isolated in Africa (Bell 1996; Spradbrow 1996; Verwoerd 1996). ND is the one disease which is well known by most FP-keeping farmers. They often can even predict the period in which it generally occurs, although they do not usually know the causes of the disease. In many local communities, FP-keeping farmers have names for the disease in their local languages/dialects. FP-keeping farmers are at least usually well aware of the virulence of ND, especially in chickens; the disease frequently leaves no survivors in unvaccinated flocks. Village farmers in western regions of the Democratic Republic of Congo therefore call this disease ‘the bomb’, as it causes a huge number of victims in their poultry flocks after its occurrence, as a bombshell would do.

Typically, there is an annual passage of ND in rural areas of most LIFDCs, and the survivors have a high level of antibodies, which are initially passed on to the next generation in the form of maternal antibodies. These gradually decline, and at the next viral challenge the antibody levels of those with some antibodies are boosted, whereas those with no protection succumb, and so the cycle is repeated (Bell 1996). Serological surveys are mostly conducted on chickens, which represent the most important poultry species kept in rural areas of most LIFDCs. For example, in Africa, studies of unvaccinated but apparently healthy village chickens showed that ND is very widespread, with percentages of seropositive chickens ranging from 5 to 98 % (Guèye 1999a). Poultry species seem to be differently susceptible to ND. According to most farmers, ducks and geese and, to a smaller extent, guinea fowls are more resistant to the disease. Moreover, the season has an effect on the severity of ND, as it seems to flare up in village chicken flocks during the rainy seasons in two East African countries, i.e. Kenya (Anonymous 1996) and Ethiopia (Sonaiya et al 1999), while in West and Central Africa major outbreaks seem to occur generally during the dry seasons (Grundler et al 1988; Mukiibi Muka 1992; Yongolo 1996; Bonfoh 1997; Guèye 1998). In India, the ND outbreak is during the summer months when it is hot and dry (E J Raymond, personal communication). On the whole, it is the bad weather that tends to favour ND outbreaks.

No progress has been made in controlling ND in free-ranging village flocks, which represent more than 80 percent of the total poultry population in LIFDCs (Branckaert and Guèye 2000). In most LIFDCs, ND occurs every year and kills on average 70 to 80 percent of the unvaccinated rural FP (Branckaert and Guèye 2000). Therefore, ND control can appropriately be used as an entry-point for developing the FP sub-sector as a whole (Guèye 2002b).

It is however extremely difficult to organize vaccination campaigns covering free-range birds, and the main constraints are related to the characteristics of the husbandry systems practised (i.e. small flock sizes, multi-age birds, scattered flocks over a vast area, birds not usually housed, etc.). Moreover, conventional vaccines are not available either in small-doses or in small-lot ampoules. Cold storage, which these thermolabile vaccines require, is not available in rural areas in LIFDCs. The heat-resistant vaccines against ND (i.e. V4 and I-2 strains) developed by Peter B. Spradbrow and his colleagues at the University of Queensland in Australia appear to offer considerable prospects for controlling ND in rural FP (Spradbrow 1996, 1999, 2000; Guèye and van’t Hooft 2002). For instance, a trial carried out under village conditions in central Tanzania revealed that about 70-80 % of the birds vaccinated using the V4 vaccine were protected again ND (Spradbrow and Foster 1997). One of the greatest advantages of these vaccines is paradoxically that not all vaccinated birds are protected (although the level of protection is high). This gives enough time to FP-keeping farmers to upgrade their skills in overall poultry management gradually, especially as other constraints may arise after the control of ND (e.g. other diseases, feeding, housing, marketing, etc.) (Guèye 2002b).

It should be kept in mind that, besides vaccination, other general approaches can be used to control ND. These include hygiene, slaughter of infected birds and selection for resistance to the disease or for a better immunological response (Branckaert and Guèye 2000). Moreover, once ND is controlled, other diseases (i.e. fowl pox, fowl cholera, Gumboro, coccidiosis, ecto- and endoparasites, etc.) will become relatively more important, and the resulting larger flock sizes will also most likely exacerbate other management-related problems. Biosecurity issues will then become more acute (Aini 2000). The following activities are recommended with regard to the control of important diseases,  including ND, in LIFDCs:

·         Methods of disease diagnosis, monitoring and control that are specifically applicable to FP systems should be developed and validated.

·        Epidemiological surveys at national, regional and continental levels should be conducted.

·        Based on the survey results, appropriate and low-cost vaccination schemes should be proposed.

·        Identification of more robust and effective vaccines and more efficient delivery routes should be pursued.

·        Programmes for FP disease control should be devised and implemented at regional or continental levels.

·        Training and use of paravets, preferably women, should be undertaken to carry out vaccination at group level. They must work in tandem with private or governmental veterinarians, whenever possible.

·        More research on the efficacy of alternative methods of disease prevention and treatment (i.e. EVM) under controlled conditions must be carried out (Danø and Bøgh 1999; Guèye 1997, 1999a, 1999b; Mathias and Perezgrovas 1999).

Significance of EVM

The high incidence of diseases, especially ND, is one of the principal constraints to FP production systems in LIFDCs. The generally resource-poor FP-keeping farmers in LIFDCs do not have money for, or access to, cost-intensive management systems, including chemical medicines. With the aim to controlling important poultry diseases, including ND, and thus to prevent high mortality rates, FP-keeping farmers rely on their ancestral indigenous knowledge (old traditions), by regularly making use of EVM (Table 1). In EVM, traditional natural products, especially plant products, are generally used for the treatment and/or, in some cases, for the prevention of ND. This ethnoveterinary knowledge is in the custody of older men and women, who pass on it to younger generations by word-of-mouth, which is still an important means of communication in LIFDCs. This means that modifications may have been introduced at various stages, and the surviving information may dwindle due the advance of the ‘modern’ medicine and the decline of the tradition. According to Bizimana (1994), part of this knowledge is available to all poultry keepers and another part is a jealously guarded family secret.

EVM is usually the only alternative for most of these resource-poor FP-keeping farmers, especially in remote, rural and hill areas, as there are almost no veterinarians working in such regions. In the absence of severe droughts, plant products with recognised medici­nal properties can be collected either at no cost or obtained very cheaply (Guèye 1997). These locally available plant products are suitable for use by FP-keeping farmers who can prepare their own remedies for their poultry. Given the foregoing considerations, it can be stated that, on the one hand, the use of EVM is obviously sustainable as it is culturally acceptable and accepted, and financi­ally and ecologically sound; on the other hand, much of this precious knowledge is in danger of being lost or suppressed (Guèye 1999b).

FP-keeping farmers tend to use the same traditional medicinal remedies for treating related disease conditions in both humans and poultry. This fact is not surprising as most diseases that affect poultry induce symptoms that are similar to those caused by some ailments in human beings (e.g. pest, pox, cholera, etc.), although the farmers do not often known the causes of diseases. Additionally, there are often ‘humanized’ relationships between humans and poultry. This arises from the fact that, firstly, small poultry flocks are usually kept by producers, and secondly, in many cases, humans and poultry live within the same house. For example, it is not uncommon for village farmers in Senegal to name their birds after people (Figure 1).

 Figure 1. Use of traditional medicinal remedies in humans and family poultry in LIFDCs

Furthermore, Islam and Kashem (1999) suggest the following formula to ascertain the extent of use of EVM: 

EVMUI = N1 x 3 + N2 x 2 + N3 x 1 + N4 x 0

where, EVMUI = Ethnoveterinary Medicine Use Index

N1 = Number of farmers who use the EVM frequently

N2 = Number of farmers who use the EVM occasionally

N3 = Number of farmers who use the EVM rarely

N4 = Number of farmers who do not use the EVM at all

For example, in a study carried out in 110 households in Bangladesh, the score 132 was obtained for EVMUI when an EVM practice (feeding ripe chilli blended with kerosene and warm boiled rice to cure the ND in poultry) was considered.

Control of ND

Prevention of ND

In most LIFDCs, rural FP are almost never vaccinated against ND with standard Western-type vaccines. Very occasionally these birds are given antibiotics originally intended for human use. FP-keeping farmers, especially in rural areas, tend to start dealing with disease control once the symptoms appear in their flocks. They therefore treat symptoms instead of diseases and link specific therapeutic preparations to specific disease symptoms. However, in The Gambia, one preventive measure (‘vaccination’) traditionally used by FP-keeping farmers against ND consists of blending the excreta from any wild birds with goat’s milk and giving the resulting mixture to village chickens to drink (Bonfoh 1997). A similar use of the entrails of chickens that have died of ND has also been reported. The chickens’ entrails are soaked in goat’s milk and then the resulting infusion is given orally to the birds. These practices may have some protective effect but cannot be recommended because the entrails are very likely to contain the virulent ND virus (Guèye 1999b). The use of the milk is scientifically well-founded, as it generally serves as stabilizer for inactivated viruses in vaccine preparations (Guèye 1998, 1999a, 1999b).

Chicken farmers in rural Botswana argue that, before ND attacks, they feed their chickens on green mulberry leaves to induce diarrhoea and claim that chickens that have been subject to this treatment do not contract the disease (Moreki 1997). In Zambia, Kaoma and Chiteta (2001) reported that mortality was reduced by 100% when Euphorbia ingens (Giant Cactus) was given to local chickens before the occurrence of ND (mode of preparation: the branches of the cactus were pounded, mixed with water and thereafter left overnight; the mixture was then sieved and the liquid solution given to chickens). It can be assumed that village poultry farmers are aware of the fact that the principle of the vaccination consists of producing a mild form of the disease, and they recognise the diarrhoea as being one of the symptoms of this disease.

Treatment of ND

To treat ND, which is an infectious disease affecting several organs, many plant-based products are used by FP-keeping farmers in Africa (Table 2). The application form con­sists usually of soaking plant products (i.e. bark, leaves, latex, stems, fruits, seeds and flowers) in drinking water. In this case, poultry should be prevented from drinking any other water (Guèye 1999b).

FP-keeping farmers living in the same location may use different preparations to treat a specific poultry disease. For example, a survey of 150 households recently conducted in the peri-urban area of Dakar, Senegal, revealed  that the following traditional remedies are used against ND in chicken flocks: fruits of Capsicum sp. (in 38% of the surveyed households), barks of Khaya senegalensis (in 25% of households), barks or leaves of Azadirachta indica (‘niim’) (in 8% of households) and other plant-based products (Anacardium sp., boiled leaves of Mangifera sp. and fruits of Capsicum sp. + Pipper nigrum) (in 7% of households).

Although FP-keeping farmers claim that EVM used against important poultry diseases, including ND, is effective, there are only very few experiments carried out under controlled conditions in order to test these traditional remedies. These experiments conducted for poultry diseases other than ND have scientifically validated traditional remedies (Guèye 1999b). Yet, a recent study carried out in Zambia revealed that the use of Euphorbia ingens in a experiment reduced mortality in local chickens by 38.4% when given during an outbreak of ND (Kaoma and Chiteta 2001). However only 20 local chickens were used in the study.

 It is necessary to test more extensively the efficacy of the various concoctions used by FP-keeping farmers to treat ND. Although all traditional remedies currently used are not likely to be effective, it is reasonable to expect that some local therapies work effectively. The aim of the experiments to be conducted is to identify those local therapies which are working effectively, before their extensive recommendation to FP keepers. One positive point in favour of this expectation is that some traditional remedies are used by FP-keeping farmers living in regions that are sometimes geographically very isolated. For example, the use of Aloe sp. leaf extract is a local therapy that is reported to be used in a Western African country (i.e. The Gambia), in Eastern African countries (i.e. Kenya and Tanzania) and in Southern African countries (i.e. Botswana, Zimbabwe and Mozambique). Even 8% of the 25 small-scale broiler farms in the commercial poultry sub-sector surveyed in Botswana used Aloe sp. leaf extracts to treat their birds against ND (Aganga et al 2000). Moreover, Capsicum sp. is reported to be widely used to treat various unknown diseases, including ND. Capsaicin, the pungent agent in Capsicum sp. was indeed found to increase bird’s resistance against major health threats (Guèye 1998).

Ethnoveterinary plant products involved in the treatment of ND are of various botanical families (Table 2); such as Mimosaceae (Parkia sp.), Caesalpiniaceae (Cassia sp.), Euphorbiaceae (Euphorbia sp.), Solanaceae (Capsicum sp.), Cucurbitaceae (Lagenaria sp.), Meliaceae (Khaya sp.), Anacardiaceae (Mangifera sp.), Liliaceae (Aloe sp.) and Agavaceae (Agave sp.). This list, which is far from being exhaustive, demonstrates that a great number of plants, including those that are used to treat other poultry diseases (Guèye 1999b), have to be protected and/or conserved to enable FP keepers to make good use of their products. Thus, the concern of the poultry specialists joins that of the people concerned with the protection of plant biodiversity. These people must then work together within multidisciplinary teams, which must include other specialists such as farmers, pharmacists and other professionals (i.e. extension workers, communicators, socio-economists, human geographers, sociologists and social anthropologists, planners, policy makers, etc.).

Prospects for the use of EVM for the control of ND

In LIFDCs, there are many medicinal plants which are, and might be, suitably used for the treatment of ND, although there is generally a scarcity of information on application rates. However, some plants regarded by FP-keeping farmers as being of medicinal value to poultry are in danger of extinction, especially in arid zones. It is therefore important that these plants are listed, with a view to ensuring their protection and/or genetic conservation. Besides this, ethnoveterinary knowledge is gradually being lost. Thus, field observations on the current use of EVM should be more broadly published in the literature and/or extended in order to help meet poultry healthcare needs among farmers. With regard to the ND control, future field experiences to be reported should include, at least, the following relevant para­meters:

•  Poultry species that are concerned: chickens, turkeys, guinea fowls, ducks, pigeons, etc.

• Plant product to be used: barks, leaves, roots, stems, fruits, bulbs, juice, latex, etc.

•  Other products to be associated with the main plant products used: soot, salt, soap, other plant products, etc.

•  Application form: drinking water, decoction, infusion, pulverisation, etc.

• Application rate: e.g. for plant products to be administered through drinking water: g (sun-dried) powdered plant product per litre of water per kg of bird live weight

Scientific validation of EVM, through experiments on the efficacy of these traditional remedies under controlled conditions, is necessary for a significantly increased use of many such remedies, as they will be more feasible, and the results obtained would be more comparable. Consequently, the value of EVM will become more easily recognised by scientists, veterinarians, pharmacists and other professionals concerned with poultry health.

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Received14 October 2002

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