Diagnosis and epidemiology of chicken infectious anemia in Africa

Abstract

Chicken infectious anemia (CIA) has recently emerged as an important disease problem in some of Africa’s major poultry-producing countries. Economic losses due to this disease arises from poor growth, increased mortality, carcass condemnations and the cost of antibiotics used to control secondary bacterial infections. Thus, it constitutes a significant threat to the continent’s food security efforts. Published studies were reviewed to obtain data on techniques used for serological detection as well as biological and molecular diagnosis of CIA virus (CIAV) in Africa. In the African countries where CIAV has been reported, diagnosis involved the use of serological, biological and nucleic acid-based detection techniques. While serological investigations detected CIAV antibodies in chickens in South Africa, Egypt and Nigeria, monoclonal antibody reactivity showed that CIAV isolates from Nigeria were antigenically related to the reference Cuxhaven-1 virus. The polymerase chain reaction detected CIAV DNA in tissues, blood and sera of infected chickens while restriction endonuclease analysis indicated the circulation of a mixed population of CIAV strains among chickens in Africa. Analysis of sequenced isolates revealed that the amino acid composition of African CIAV strains was highly conserved. The implications of these findings for the epidemiology and control of CIA in African poultry are discussed.