New Castel Disease In Ethiopia: A Review

Livestock production is a major component of Ethiopian economy. In developing countries like Ethiopia, livestock production goes well beyond food production; sales of livestock and their products provide immediate cash income to farmers and foreign exchange for the countries (FAO, 1990). Poultry production will assist in poverty alleviation and the improvement of food security. The increased availability of village chickens and eggs should result in an improved intake of protein by the population and increased access to cash and other sources. Chickens are often essential elements of female-headed and poor households. This is particularly important contribution in areas where child malnutrition is common. Malnutrition wider implications for development because protein-energy malnutrition in children inhibits their growth, increase their risk of morbidity, affect their mental development, and reduce their subsequent school performance and labour productivity (Alders and Spradbrow, 2001). Chickens in traditional village poultry systems provide scarce animal protein in the form of meat and eggs, and are available for sale or barter in societies where cash is not abundant. They are generally owned and managed by women and children. Chickens also fulfill a range of other functions for which it is difficult to assign monetary value. They are active in pest control, provide manure, are required for special festivals and to meet social obligations, they are essential for many traditional ceremonies and traditional treatment of illness (Robyn and Spreadbrow, 2001). Raising poultry has along line of tradition in Ethiopia and the production system shows a clear distinction between the traditional subsistence, low input system compared with small and large-scale commercial systems, which use relatively advanced technology. Indigenous birds are raised under traditional; or ‘’backyard’’ conditions without any input and are difficult to monitor. They comprise up to 99% of the total estimated, 56.6 million chickens in Ethiopia, while 1% are an exotic breed maintained under intensive management system (Hagos et al ., 2003). Most poultry improvement programs in developing countries including Ethiopia have been directed towards the introduction of specialized exotic breeds or cross breeding and management intensification. Genetic improvement could be achieved either through selection and controlled mating or by introducing exotic chickens (Aklilu, 2000). There are many constrains to village chicken production including a range of bacteria and other viral disease, internal and external parasites, poor nutrition and predation (Robyn and spradbrow, 2001). The major constraint to productions of village chickens in many developing countries is Newcastle disease. In these countries circulating strains of NCD virus are capable of causing 100% mortality in unprotected flocks, outbreaks of NCD are unpredictable and discourage villagers from paying proper attention to the husbandry and welfare of their chickens. The Importance of NCD is indicated by the fact that NCD has a local name in many countries. Newcastle disease is a serious and commonly fatal viral poultry disease, which is present all over the world. In many tropical and subtropical countries, virulent strains of NCD virus are endemic (Barman, 2002). In most developing countries, NCD is the most important infections disease affecting village chickens and causes great economic losses (Alders and Spradbrow, 2001). The disease is caused by a paramyxovirus, which is readily inactivated by formaline, alcohol, merthiolate. NCD virus may persist in undispersed chicken faeces for more than six months but under village conditions the virus can survive outside the host for more than one month. NCD viruses occur in three pathotypes: Lentogenic, mesogenic, and velogenic. The most virulent (velogenic) isolates are further sub-divided into neurotropic and viscerotropic. In chickens NCD is characterized by lesions in the brain or gastrointestinal tract, morbidity rates near 100%, and mortality rates as high as 90% in susceptible chickens. Neurological symptoms or severe depression are the most obvious clinical signs of NCD Such as loss of appetite, anorexia, yellowish or greenish diarrhea and paralysis and some unvaccinated birds may be found dead with no detected sign of prior illness (Serkalem et al., 2005). The prevailing management system, which involves exposure to wild birds, selling or giving away of sick birds, absence of vaccination programs and unrestricted contact between the different flocks are believed to facilitate the rapid spread of infection and persistence of the disease among the village chickens (Tadelle and Yelma, 2004). NCD virus possesses two surface proteins that are important to the identification and behavior of the virus. The first, hemagglutinin /neuraminidase (HN) is important in the attachment and release of the virus from the host cells, in addition to its serologic identification. The other very important surface protein is the fusion (F) protein, which has a critical role in the pathogenesis of the disease. Vaccination against NCD is routinely practiced throughout the world. In Ethiopia, intensive poultry farms vaccinate their poultry routinely, but poultry in extensive production systems are not vaccinated routinely due to lack of proper knowledge and it is difficult to transport and maintain conventional thermolabile vaccines in ambient temperatures ranging from 24 0 c to 36 0 c (Alders and Spradbrow, 2002). Reports from six African countries, indicated that the mortality caused by NCD ranges from 50 – 100%. In addition, Spreadbrow (1991) indicated that NCD is the most devastating disease of village poultry responsible for heavy losses. It seriously interferes with the development of the poultry industry since farmers consider the disease as a serious constraint to investing in poultry (Tadelle and Yilma, 2004). In Ethiopia, poultry diseases are considered to be the most important factor responsible for reducing both the number and productivity of chickens. Poultry diseases such as New castle disease, coccidiosis, and nutritional deficiency are considered to be the most endemic and the ones to incur huge economic losses. Study was conducted in 5 selected sites in central Ethiopia ( Jeldu, sebeta, Awash-melka-kontire, Debreberhan and Nazareth.) has shown that is one of the major infectious disease which constrain poultry production (Hagos et al .,2003; Serkalem et al .,2005).