Studies on Avian Influenza in Khartoum State

Abstract

The present work was carried out on avian influenza in Khartoum State. The aim of the work was to make field observations on the disease, carry out a serological survey to detect antibodies against the virus and to isolate and identify the virus. An outbreak of the disease occurred in a farm in Khartoum North area during winter in February 1998. This was the only outbreak in the area during the period of this study. The farm had a population of 10000 (four to eight months old) white Bovan birds. Seventy per cent of the birds showed clinical signs, but the mortality rate was 5%. Clinical signs were ruffled feathers, oedema of the head, cyanosis of combs and wattles, respiratory signs such as nasal discharge, lachrymation and diarrhoea. A total of 31 isolates were recovered from 22 cloacal swabs, 33 tracheal swabs and 42 tissues (trachea, lung, liver, spleen and heart) in the allantoic fluid of 11 - day - old embryonated chicken eggs. Twenty of embryos died within 36 to 96 hours post inoculation. Eighteen of the isolates was recovered from tactical swabs, 12 from tissues and one from cloacal swabs. Examination of the chorioallantoic membrane showed haemorrhage and thickening. All 31 isolates agglutinated chicken RBCs, indicating that they might be influenza viruses. Negative haemagglutination inhibition (HI) test established the absence of Newcastle disease. Agar gel precipitation test (AGPT) was used to identify influenza virus type A. 6.5% of the isolates were inhibited using influenza antiserum (H3N2) using HI test. Enzyme - linked immunosorbant assay (ELISA) and AGPT were used to detect antibodies in chicken sera. Eighteen per cent of the sera were found positive by AGPT and 28.4% were positive by ELISA. This work reports for the first time in the Sudan isolation of AIV and the presence of antibodies in sera from chickens.