The recent occurrences of Avian Influenza, or bird flu, in humans in India and China have raised global concerns. In India, the first human fatality was documented this year due to the H5N1 strain, while China announced its first human infection of the H10N3 strain. This article discusses the key aspects and impacts of this disease, as well as the necessary preventative and eradication measures.
Understanding Avian Influenza
Avian Influenza (AI) is a disease caused by Type A viruses that are found naturally in wild birds across the globe. The AI viruses can be either Low Pathogenic AI (LPAI) or Highly Pathogenic AI (HPAI), categorized based on their pathogenicity. The H5N1 strain belongs to the HPAI group. Besides affecting poultry such as chickens, ducks, and turkeys, the H5N1 virus has also been reported in pigs, cats, and even tigers in Thai zoos.
Impact on Agriculture and Livestock
An outbreak of the AI virus can lead to catastrophic consequences, particularly for the poultry industry. Farmers may witness mortality rates in their flocks of about 50%.
Transmission and Effects in Humans
The primary route of transmission in humans is through direct contact with infected birds, whether dead or alive, or exposure to contaminated surfaces or air near the infected poultry. Human-to-human transmission of the H5N1 virus is extremely rare. Individuals under the age of 40, especially those aged 10-19, are the most vulnerable, and cases can result in high mortality rates. Symptoms range from mild to severe flu-like illnesses, which may develop into serious respiratory conditions and other severe health issues.
Prevention and Control Measures
Implementing strict biosecurity measures and good hygiene practices is essential to protect against disease outbreaks. If an infection is detected in animals, a usual policy is to cull the infected and contact animals to rapidly contain, control, and eradicate the disease. The Global Influenza Surveillance and Response System (GISRS), a global laboratory system established by WHO, identifies and monitors circulating influenza viruses and advises countries on health risks and available treatments.
Status of Bird Flu in India
Between December 2020 and January 2021, fresh cases of bird flu were reported across various Indian states. This was alarming because India had been declared free from Avian Influenza (H5N1) in 2019, a notification that was relayed to the World Organisation for Animal Health (OIE), headquartered in Paris, France.
Understanding Different Types of Influenza Viruses
Four types of influenza viruses exist: A, B, C, and D. Types A and B cause epidemic seasonal infections almost every year, while Type C mainly affects humans, dogs, and pigs. Type D is primarily found in cattle and is not known to infect or cause illness in humans. Type A viruses are further classified based on two proteins on their surfaces – Hemagglutinin (HA) and Neuraminidase (NA). There are about 18 HA subtypes, 11 NA subtypes, and several possible combinations of these two proteins, such as H5N1, H7N2, H9N6, etc.
Future Prospects
Monitoring wild bird and animal diseases could serve as an early warning system for potential diseases. There’s a requirement for a comprehensive study to screen poultry and domestic waterfowl for low pathogenic viruses. Research indicates that blocking the mixed-use of surface water by domestic poultry and wild waterfowl could interrupt the Avian Influenza cycle. As a result, monitoring multiple waterbird sites of local, national, and international significance should be emphasized.