New lab test to detect bird flu virus on anvil

The Indian Council for Medical Research (ICMR) has developed a novel method by which Avian Influenza (AI), commonly known as Bird Flu virus, can be detected from environmental specimens such as droppings of birds (wild and migratory) and water bodies.

The test, which has been made by ICMR's virology institute- National Institute of Virology (NIV) in Pune, is going through a trial run in the institute and will soon be made available for the public.

This is a novel, sensitive, user-friendly and cost-effective method for the detection of AI viruses from environmental water specimens, which has the potential of its use for the detection of AI viruses during outbreak investigations.

In the laboratory, this method has been tested on fresh water specimens from dams and salt water samples drawn from the Arabian Sea. AI viruses were found to be present in majority of the water samples.

There are very few methods available for the detection of AI viruses from water; filtration method based on adsorption-elution; virus concentration by binding influenza virus onto erythrocytes and filtration-elution and polyethylene glycol (PEG) concentration. However, these methods are cumbersome and time-consuming, said the experts.

"This is for the first time that such a test has been developed. Earlier, we used to face difficulty in looking at the virus in water samples. This will help in monitoring the water bodies as well. The test has been developed by NIV and it has been sent for the final publication. Once it is published, we will be using it in other centres," said Dr Soumya Swaminathan, director-general, ICMR.

"Experimentally, avian influenza viruses have been shown to persist in water. It is also known that the highly pathogenic H5N1 virus may remain viable in feces at low temperatures and may act as a long-term source of influenza virus in the environment. Therefore, monitoring water and other environmental specimens is necessary for detection and characterization of AI viruses," said Dr Shailesh D. Pawar, a scientist from NIV involved in the trials.

Wild aquatic birds such as geese, shorebirds, wild ducks and bats are the natural reservoirs of influenza-A viruses. The Bird flu virus transmission occurs by contact between infected and susceptible hosts. The new method was developed six months back and the team has worked on it for almost nine months.

"Water-borne transmission of AI viruses has been suggested as an important transmission mechanism in domestic ducks and wild birds. There are earlier reports of AI viruses isolations from water bodies where waterfowl gather and the virus can persist for a longer period of time. Areas such as lake, ponds, dams where aquatic and migratory birds rest during their migration may be contaminated with AI viruses," said Dr DT Mourya, director, NIV.

The national capital has recently witnessed few cases of bird flu, after which few birding places- Delhi zoo and Deer park were shut to prevent further spread of the disease. In wake of increasing cases, Delhi government had also decided to monitor all the parks, forest areas and water bodies in the national capital.

In 2011, the research institute had done a surveillance of wild, poultry, migratory and residential birds in six states. It was found that some migratory birds had H11N1 and H4N6 virus in them.

According to the experts, higher rate of AI virus isolation from drinking water containers of poultry in live poultry markets were reported as compared with droppings, tracheal and cloacal swab specimens.

"One of the advantages of this method is easy concentration of AI viruses from the large volume of water," said Dr Mourya.

KNOW THE VIRUS

• Avian influenza (AI), commonly called bird flu, is an infectious viral disease of birds.
   
• Most avian influenza viruses do not infect humans; however some, such as A(H5N1) and A(H7N9), have caused serious infections in people.
   
• The majority of human cases of A(H5N1) and A(H7N9) infection have been associated with direct or indirect contact with infected live or dead poultry. There is no evidence that the disease can be spread to people through properly cooked food.
   
• Controlling the disease in animals is the first step in decreasing risks to humans.
   
• The A(H5N1) virus subtype, a highly pathogenic AI virus, first infected humans in 1997 during a poultry outbreak in Hong Kong SAR, China
   
• Since its widespread re-emergence in 2003 and 2004, this avian virus has spread from Asia to Europe and Africa and has become entrenched in poultry in some countries.