The poultry sector in Pakistan is the second largest industry that contributes to the national gross domestic products (GDP) and remains a major source of nutrition (protein and energy) for human population in Pakistan. Highly Pathogenic Avian Influenza (HPAI) outbreaks due to H5N1 virus in poultry have been recorded in over 62 countries, indicating the contagious nature of the disease and its potential to infect various avian species. These HPAI outbreaks in poultry have lead to killing/culling of around 120 million birds in various countries. During 2009, the Avian Influenza continues to occur in poultry in China, Hong Kong, India, Egypt, Nepal, Bangladesh and Canada . In Pakistan, an HPAI outbreak due to H7N3 virus was first observed in 1994-95 and those due to H9N2 virus in broiler and layer chickens were recorded between late 1990’s and early 2000. During the period between 2006 and 2008, poultry heavily suffered due to multiple outbreaks caused by H5N1 virus.
The country experienced several and severe HPAI subtype H5N1 outbreaks during 2006-2008 in commercial poultry farms mostly, causing mass economic losses. In Pakistan all the four poultry production system exists being identified by FAO. The present study was conducted in peri-urban areas of ICT Islamabad, capital of Pakistan. The objectives of the present study were to investigate the outbreaks due to HPAIV H5N1 in 2006-2007 in ICT and identify the pattern and trends of these outbreaks. For this purpose descriptive epidemiological study was conducted and data was collected on a predesigned questionnaire regarding farm demography, culling, morbidity and mortality. The result statistical analysis showed a significantly (P< 0.05) higher morbidity, mortality, case fatality and culling rate in layers farms than breeders and broilers respectively. Layers and breeders of old ages were mostly affected with having higher mortality and culling in comparison to younger age layer and breeder commercial farms. The mean morbidity and mortality rates ranged 57–95% and 5-43% correspondingly.
After the HPAIV H5N1 first reported outbreak in Pakistan in 2006 culling strategy was adopted after devastating outbreaks regularly reported from throughout the country. The reasons behind these emerging epidemics were unknown and several hypotheses were given birth after these outbreaks. Knowledge regarding potential risk factors responsible for HPAIV H5N1 epidemics in commercial poultry farms in Pakistan was lacking. Therefore we conducted a longitudinal cross sectional survey (1:1 matched case control study) to identify potential risk factors at farm level responsible for 2006-2007 HPAIV H5N1 infection in poultry in ICT. Information on farm characteristics, biosecurity practices and farm management were collected. Logistic regression model on data was used to unveil the potentially associated risk factors with cases (farms confirmed HPAI H5N1 Positive). Several candidate variables were studied and investigated for association. The results multivariable logistic regression showed that farm location such as in urban area (P<0.05: OR=18.50), wild birds entry (P<0.05: OR= 12.66) and farms situated in highly dense poultry populated area (P<0.05:OR=4.50) were found significantly associated with outbreaks of HPAIV H5N1 infection in commercial poultry farms during 2006-2007 epidemics in the study area.
Live bird markets (LBMs) are essential for poultry marketing in developing countries like Pakistan. One year active disease surveillance for influenza viruses in avian species in LBMs in ICT area was conducted in 2011. LBMs in Pakistan are typically urban that brings together many avian species produced by different suppliers. Which make LBMs in Pakistan a potential source of HPAIV viruses as well as other emerging poultry pathogens i.e. new castle disease virus,infectious bronchitis etc. The results of the present surveillance data showed that seroconversion against H5N1 and H9N2 is present in LBMs bird species which were isolated from different samples like serum, cloacal, nasal samples and organ samples.This indicates the continuous threat of AIV viruses circulating in the live bird markets set up of Pakistan.
Findings of these studies will help to tailor control and prevention measure against devastating outbreaks in future regarding the local circumstances of commercial poultry farms as well as in LBMs. These studies also succeeded to unveil the true reasons behind these devastating outbreaks and their higher impact on poultry industry. Such type of surveillance programs will be useful in future to investigate several emerging diseases and outbreaks in Pakistan and other developing countries.