Prevalence of avian influenza in domestic scavenging ducks of some selected areas (Sylhet and Savar, Dhaka) in Bangladesh

Abstract

Avian Influenza is an infection and/or disease syndrome of birds as well as in humans and lower mammals caused by Type A influenza virus, a member of the family Orthomyxoviridae that is more than 100 years old (1 recogninized in 1878 in Italy) and now is of sparked concern due to its fatality and zoonosis. Type A influenza viruses are further divided into subtypes based on antigenic relationship of the haernagglutinin (HA) and neuraminidase (NA) surface glycoprotein. To-date sixteen (16) unique HA subtypes (HI-H16) and nine (9) unique NA subtypes (N1-N9) have been recognized. Each virus has one HA and one NA protein, potentially in any combination. Influenza A virus infecting poultry can be divided into two distinct groups on the basis of their ability to cause disease. All highly pathogenic avian influenza (HPAI) viruses that cause generalized fatal disease belong to either the H5 or H7 subtypes. However, H5 and H7 virus may circulate in the nature as low pathogenic avian influenza (LPAI) strains for certain period of time before they mutate into highly pathogenic strains. Therefore, irrespective of pathogenicity, all H5 and H7 Al viruses are considered as Notifiable Avian Influenza (NAI) viruses. The present study was therefore undertaken with the following specific objectives and the ultimate goal of this study is to know the status of AIV in domestic scavenging ducks to find out their role in Al transmission from migratory birds to chickens-isolation and identification of Avian Influenza Virus (AIV) type A from domestic scavenging ducks in some selected areas of Bangladesh like Sylhet and Savar, Dhaka. Bangladesh and detection of Sero-prevalence of Avian Influenza Virus (AIV) type A within the selected study areas. For the detection of seroprevalence of avian influenza virus (AIV) type A and isolation and identification of this virus, samples were collected randomly from the two areas the different locations in Sylhet District of Bangladesh (area-1) and Savar, Dhaka, Bangladesh (area-II) during the period of July 2009 to December 2009 Convert For seroprevalence, 92 sera samples were collected and preserved at -20°C & ELISA test was performed for the detection of antibody of avian influenza virus (AIV) type A. The overall seroprevalence of Al in domesticdetection of antibody of avian influenza virus (AIV) type A. The overall seroprevalence of Al in domestic scavenging ducks within the both study areas was 35.9% (33/92). The lowest seroprevalence was 27.5%

(11/40) in study area-1 and the highest seroprevalence was 42.3% (22/52) in study area-II. For the isolation and identification of avian influenza virus (AIV) type A, a total of 533 cloacal swabs were collected from domestic scavenging ducks and investigated for virus isolation through chicken embryo inoculation and HA teskond the virus was identified by the molecular technique, RT-PCR (Reverse Transcription Polymerase Chain Reaction). In this study, 3.6% samples (19/533) of harvested AF were found to be positive to hemagglutinating viruses.

The overall prevalence of hemagglutinating viruses in this study was 3.6%, whereas the lowest prevalence was found 3.3% (7/210) in area-I and the highest prevalence was found 3.7% (12/323) in area-II. In the present study, Molecular technique RT-PCR was performed to detect AIV type A from those HA positive Allantoic fluids (AF). A total of 0.6% (3/533) samples were positive by RT-PCR with the AIV NP specific primer set. Finally it can be concluded that as highly pathogenic avian influenza (HPAI) has been emerged as a great global concern for its socio-economic and public health impact. The disease has been posing a serious threat to the poultry sector all over the World including Bangladesh. For effective control, proper and early diagnosis is the key point