Outbreak of highly pathogenic avian influenza subtype H5N8 in two multi-age chicken farms in Jos, Plateau State, Nigeria

Abstract

An outbreak of highly pathogenic avian influenza (HPAI) subtype H5N8 in two multi-age chicken flocks in Jos, Plateau State, Nigeria, is described. Diagnosis was made using tissue samples from the affected farms that were submitted to the Regional Lab for Animal Influenza and other Transboundary Animal Diseases, National Veterinary Research Institute, Vom. Pullets with broilers of 9 and 4 weeks of age respectively, from farm A (fA) and broilers, 4 weeks of age from farm B (fB) were submitted from flocks experiencing a drastic increase in mortality. The February 2019 outbreak resulted in10 – 60 % and 60 % mortality on fA and fB respectively. Clinical signs included anorexia, depression, hock sitting and sudden onset of increasing mortality. Gross lesions included edema of the head with cyanosis of comb and wattle; swollen abdomen due to ascites; generalized congestion of visceral organs with frank blood in the abdomen; congested mesenteric vessels with haemorrhages in the mucosa of small and large intestines; congested and frothy lungs with severe hemorrhagic tracheitis among others. In view of the clinical and gross pathology, HPAI was considered as the tentative diagnosis. Diagnosis of HPAI subtype H5N8 was confirmed by reverse transcriptase polymerase chain reaction and viral isolation in embryonated chicken eggs. The current outbreak has shown the presence of HPAI H5N8 in the country different from the H5N1 subtype that was introduced since 2006 in Nigeria. The co-circulation of these two subtypes if the current wave of infection is left unchecked will have adverse effects on poultry production, international trade and human health. Hence, the need for the re-evaluation and strengthening of the Government control policy to save the poultry industry from perennial economic loses.

Keywords: Broilers, Highly pathogenic avian influenza (HPAI H5N8), Jos, Nigeria, Outbreaks, Pullets