Pregnant women, elderly population, immunocompromised individuals, those with underlying multiple comorbidities and lung diseases, as well as cardiac patients are at heightened risk, inform health experts
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The onset of winter has brought with it a novel threat of influenza virus. Known as the H9N2 virus – it primarily affects birds, particularly poultry. The virus is a subtype of the influenza A virus and has been identified in various avian species globally, informs Dr Aniket Mule, consultant internal medicine, Wockhardt Hospitals, Mira Road.
Regarding Mumbai's readiness to handle an emergency related to H9N2, Mule notes that public health preparedness is a dynamic and ongoing process. “Local health authorities would need effective surveillance, diagnostic capabilities and communication systems to respond promptly to any potential outbreak,” remarks Mule.
As the virus spreads wide in China, Midday.com spoke to health experts who delve into the characteristics of the H9N2 virus, its symptoms in humans, transmission, preventive measures and specifically, its potential impact in India.
Overview of the H9N2 virus
This viral subtype has been identified in avian species worldwide, posing a notable risk to animal and human health. While human cases are relatively uncommon, instances have been reported, typically resulting from close contact with infected poultry. The virus's global presence and its ability to affect various avian hosts underscore the importance of vigilance and monitoring to mitigate potential health risks posed by the virus.
Within the influenza A virus family, the H9N2 subtype plays a distinctive role as a major host in poultry. The virus's prevalence across diverse avian species emphasises its adaptability and potential transmission risks. Monitoring and preventive measures are crucial to limit the spread of the H9N2 virus. Also, decoding the dynamics of this influenza subtype is essential for implementing effective strategies to safeguard both animal and human health globally.
How does the virus spread?
The causes of H9N2 transmission primarily revolve around contact with infected birds and their secretions. Experts lay out a detailed analysis of the causes of H9N2 transmission:
Direct contact with infected birds:
The primary mode of transmission for H9N2 is direct contact with birds that are infected with the virus. Birds, particularly poultry, serve as the primary reservoir for the H9N2 virus. Proximity to infected birds or handling them without proper protective measures can lead to transmission.
Human cases through close contact with infected poultry:
While human cases of H9N2 are relatively rare, they can occur through close contact with infected poultry. Individuals involved in the poultry industry, such as farmers, poultry workers and those engaged in live bird markets, are at a higher risk of exposure to the virus.
Respiratory droplet transmission from infected birds:
The H9N2 virus can be transmitted through respiratory droplets from infected birds, informs Dr. Rupkatha Sen, Chief Intensivist, SRV Hospitals – Chembur. When infected birds sneeze, cough or release respiratory secretions, the virus can be present in the droplets, posing a risk to individuals nearby. The bird flu is known to cause respiratory symptoms in the chicken and turkeys, added Sen.
Rare instances of human-to-human transmission:
In some rare instances, human-to-human transmission of the H9N2 virus has been documented. While the virus generally does not have efficient human-to-human transmission capabilities, isolated cases have raised concerns about the potential for adaptation and further spread.
Symptoms
The symptoms of the H9N2 virus in humans are generally mild, encompassing fever, cough and respiratory distress, informs Mule. However, the severity of cases can escalate, particularly in individuals with pre-existing health conditions. It is worth noting that the number of people affected by H9N2 is challenging to determine precisely due to underreporting and variations in surveillance efforts.
In cases of bird flu infection, symptoms can vary widely and patients may even remain asymptomatic. In severe instances, individuals may develop lung injury or severe respiratory distress syndrome. Initial symptoms often include high-grade fever, a runny nose, throat pain, dry cough, diarrhea and nausea.
Additionally, patients may experience vomiting, extreme fatigue and lethargy. This diverse range of symptoms highlights the complexity of H9N2 infections and the importance of prompt medical attention, particularly for those exhibiting severe respiratory distress or other alarming signs.
Ways to prevent virus transmission
Mule shares that preventing the transmission of the H9N2 virus involves a dual approach, encompassing stringent biosecurity measures in poultry farms and adherence to standard precautions in humans. In poultry farms, it’s crucial to implement strict biosecurity protocols. This includes separating different bird species to minimise the risk of cross-contamination, maintaining proper sanitation practices and limiting exposure to wild birds, which can serve as potential carriers of the virus.
Regular sanitisation of poultry facilities is essential to reduce the environmental persistence of the virus and mitigate the risk of transmission among bird populations, remarks Sen. Additionally, proper hand hygiene among poultry workers is paramount, particularly those handling the feces and fluids of birds. Workers should exercise utmost care, ensuring that they change their clothing after leaving the poultry premises to prevent the inadvertent spread of the virus.
In the human context, standard precautions play a pivotal role in reducing the risk of H9N2 infection. Frequent handwashing is a fundamental preventive measure, as the virus can be transmitted through respiratory droplets or by touching contaminated surfaces. Individuals, especially those working with poultry, should avoid direct contact with sick birds and prioritise the use of personal protective equipment (PPE) such as masks and gloves to minimise exposure.
Sen emphasises that during an epidemic, the consumption of raw meat is strongly discouraged to avoid any risk of contracting the virus. Cooking meat thoroughly is recommended to ensure the inactivation of the virus and reduce the likelihood of transmission through consumption.
How severe is the H9N2 virus?
The severity of H9N2 infection exhibits a spectrum, with the majority of cases being mild, but there have been instances of severe outcomes. According to Mule, while most individuals infected with H9N2 experience mild symptoms, the virus has the potential to lead to severe complications and fatal outcomes have been reported.
The potential for the H9N2 virus to become endemic is contingent on several factors, as outlined by Mule. The adaptability of the virus, the effectiveness of control measures and the presence of susceptible hosts all play crucial roles in determining whether the virus establishes a continuous cycle within a population.
Certain populations are identified as more vulnerable to severe outcomes from H9N2 infection, as mentioned by Sen. The elderly population, immunocompromised individuals, those with underlying multiple comorbidities and lung diseases, as well as cardiac patients with uncontrolled sugars, are at heightened risk.
Pregnant women should also exercise caution, as the disease tends to progress more severely in this group. This underscores the importance of targeted protective measures, surveillance, and early medical intervention for these high-risk populations to minimise the impact of H9N2 infection.
Continuous monitoring and intervention efforts are deemed crucial in preventing the establishment of an endemic cycle, emphasising the need for sustained vigilance and proactive measures to curb the virus's spread.
However, Sen suggests that, despite its capacity to cause illness, the H9N2 virus is not highly lethal. Sen notes that the virus's concern lies in its potential to create an epidemic, driven by various mutations occurring in zoonotic diseases. While not inherently deadly, the virus's ability to undergo mutations poses challenges in predicting and controlling its behaviour, contributing to its potential epidemic potential.
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