Differential Diagnosis of Chlamydia psittaci and Avian Influenza H9N2 in Poultry of Pakistan

Abstract

Poultry contributes 2.41% to total GDP of Pakistan and is affected by various viral and bacterial infections. Avian influenza (AI) pathotype H9N2 and Chlamydia psittaci (C. psittaci) infect wide variety of poultry and result in influenza like symptoms with acute respiratory distress and loss in egg production. It is also known for the zoonotic importance. Viral-bacterial cooccurrence increases disease intensity. C. psittaci are known to enhance the AIV H9N2 infection by suppressing the host immunity. The present study was conducted on poultry of Pakistan for isolation and detection of H9N2 and C. psittaci, and to determine their co-occurrence. Total 550 samples containing 491 tissue and swab samples, and 247 serum samples were processed for isolation of H9N2 by hemagglutination (HA) and virus neutralization (VN). Conventional PCR and real time PCR were used for the detection of both AIV H9N2 and C. psittaci. Seroprevalence of serum samples for AIV and Chlamydia psittaci were checked by ELISA and confirmed by hemagglutination inhibition (HI). A total of 184 samples showed positive HA and 132 were confirmed as H9N2 by VN; 175 samples showed seroconversion for H9N2. Maximum seroconversion was observed from commercial poultry of KPK in spring season. 148 samples were found positive for H9N2 by PCR and maximum detections were from commercial poultry of Sindh in winter. Only 52 sera samples were found positive by ELISA for C. psittaci belonging to domesticated birds of Punjab in summer. Similarly, only 60 samples showed C. psittaci detection by PCR mostly from domesticated poultry of Punjab in summers. Coinfection of both was observed in 32 tissue and swabs, and 26 serum samples. It was also found that PCR was more specific as compared to in-ova inoculations. It is concluded that the chlamydial infection prevails in Pakistan alone and along with coinfection of H9N2, thus adversely affecting poultry. Proper vaccination and preventive measures must be taken to curtail their growth.