MUGHIS UDDIN AHMED*

ABSTRACT

Influenza A Virus or Avian Influenza Virus subtype H5N1 that occurs mainly in birds is mainly responsible for Bird Flu. Influenza virus belongs to family of Orthomyxovirus and it has three types Influenza virus A, B and C. Influenza A was responsible for epidemics & pandemics and it has subtypes: H-16 types (H 1-16) & N-9 types(N 1-9)1-10. Influenza B was involved in localized mild outbreaks (camps, conferences & schools etc) and Influenza C has been rarely associated with disease in human (doubtful pathogencity).

Infectious Agents of Bird Flu or Avian Influenza is from Influenza A responsible for epidemics & pandemics in birds mostly by its subtype known as H5N1 which is highly pathogenic beside H7N7, mildly pathogenic are H7N3, H7N7 and H5N7, H9N2, H7N2 are of low pathogencity11-16.
Historical Background is that the Bird Flu was first reported from poultry in early 1900 in Italy. Bird Flu was first time reported from poultry & human in 1997 in Hong Kong. From that time till 2006 it has been reported from different places. It has been reported from >44 counties around the world17-20 .

Some animals and birds are reservoir for infection. From infected bird to other bird but very rarely to human. Person to person transmission is rare and in those working in poultry farms21-27. High Risk individual are poultry workers and poultry butchers, Backyard farmers, Birds hunters, Birds handlers as pets, half cooked birds eaters and egg handlers. Incubation Period is one to four (1-4) days. Primary site for viral multiplication is the Respiratory Tract Epithelium (Tropism). Superficial epithelium of lower respiratory tract involvement results in damage to the cilia and desquamation of the epithelium27-31.

Signs and Symptoms are sudden onset of the high-grade fever, myalgia, sore throat, pharyngitis, non-productive cough, headache, cervical lymphadenopathy, chills, malaise, nasal congestion, sneezing, rhinorrhoea, sinusitis and conjunctivitis. Complications are primary and secondary Pneumonias. Communicability of infection is that the virus is excreted from the body secretions. Birds are susceptable, rarely human and wild birds are resistant to it. Mortality or fatality rate is very high (50-55%).

For Full text contact to:
Prof. Dr. Farah Mansuri
editor@annals-ashkmdc.org

*Professor Pathology, KMDC & Abbasi Shaheed Hospital, Karachi.