Differentiating H3N2v From Common Illnesses In Individuals

Introduction

What is the H3N2v virus?

Have you ever heard or read those initials and couldn’t understand what they mean? These are initials given to subtypes of Influenza, the flu virus. H3N2 is a subtype that infects and spreads in pigs (one of the so-called swine flu viruses), but when it spreads from pigs to humans they call it a variant of H3N2 (H3N2v). Other types of flu have been reported such as H1N1v and H1N2v viruses.

When did the H3N2v virus start spreading and how did the biggest epidemics happen?

The H3N2v virus, which shares the same matrix (M) gene as the H1n1 virus, started originally to spread in 2010 in the United States of America. That year, the viruses were initially discovered in U.S. pigs. Later on, twelve cases of H3N2v infection were found in the US in 2011 (in West Virginia, Pennsylvania, Maine, Iowa, and Indiana). The greatest H3N2v outbreaks were recorded in 2012 when 309 cases of the virus were found in 12 states. One person died and sixteen were admitted to hospitals in that year, the majority of which were children.¹ 

But if you are wondering about the spread in the past year, a recent outbreak in India in 2023 has been reported which was associated with more severe illness and higher mortality rates, particularly among young children, the elderly, and others with various health conditions.²

How is the H3N2 virus spreading?

Originally, the H3N2 virus was transmitted between pigs while the variant form is transmitted from pigs to humans. According to the Centres for Disease Control and Prevention (CDC), it was reported that the early cases of the variant form from pigs were in an animal environment (children exposed to pigs at an agricultural fair, people who raise pigs, or workers in the swine industry).³ This is believed to occur mostly when:

1. An infected pig sneezes or coughs, causing airborne droplets containing the flu virus to spread. You may become infected if these droplets enter your mouth or nose or if you breathe them in. 
2. There is evidence that you could contract a virus by touching your mouth or nose after coming into contact with something that has a virus on it. 
3. Inhaling influenza virus particles is a third potential method of infection. 

The most frequent of these modes of dissemination is unknown to scientists. It has not been demonstrated that consuming properly handled and prepared pork or other items generated from pigs can spread the swine flu to humans.

H3N2v symptoms and complications

The majority of variant virus infections have been moderate, with symptoms resembling the seasonal flu in humans. These symptoms are:^1,4

• Fever that ranges between 37.2℃ - 38℃
• Exhaustion, lethargy, and body aches
• Decreased appetite
• Gastrointestinal symptoms such as nausea, vomiting, or diarrhoea, especially in children
• Runny noses, sore throats, and cough
• Eye irritation

Complications could occur when this variant affects age groups that are above 65 years old or children. Additionally, individuals who are immunologically compromised or have chronic illnesses are at high risk of infection. Hospitalisation is usually due to respiratory manifestations such as breathing difficulty, decreased oxygenation, and decreased consciousness level.

Differentiating H3N2v from common illnesses

When you skim through the variant symptoms, it is difficult to differentiate them from flu symptoms. Symptoms of H3N2v are very difficult to distinguish from other common colds or other flu types. 

However, the CDC is particularly concerned about H3N2 for the following reasons: 

• Even healthy people can develop a severe form of the disease, for example, hospitalization due to severe pneumonia or even death
• H3N2 seems to have high infectivity among humans i.e it spreads more between humans than any other swine flu variant
• The influenza virus is always changing, so it is possible that it changes and soon spreads between individuals
• Immunity against H3N2 has not yet developed in those born before the first pandemic, as they were not exposed to the virus at the beginning of its spread, while adults could have probably acquired immunity

Other conditions like Influenza B or C, H1N1, allergies, and pneumonia have key differences compared to H3N2. Among these differences are:⁵

• Cough with sputum along with fatigue are more common in H3N2 but not specific to it
• Headache, body aches, and coughing of blood occur close to the H1N1 sickness uniquely characterise it
• The symptoms of pneumonia included nausea, rash, sputum, and cough 
• Allergies would have a strong previous allergic history or family history, rash or eczema and there should be a correlation to a causative agent that led to the allergic reaction
• Influenza B and C are milder and do not lead to many complications

What should be done if I suspected H3N2v infection?

• Stay at home and preferably avoid contacting vulnerable people such as children, pregnant people, elderly above 60 years, or people with chronic diseases. However, if you are from these risk groups consult your physician immediately. The CDC advises individuals who are more likely to experience problems to begin antiviral therapy as soon as feasible because the benefits increase if treatment begins within two days of the onset of the illness.⁶
• Monitor your symptoms closely, if severe manifestations occur such as coughing of blood, lightheadedness, or difficulty breathing, call the emergency services immediately.
• Keep yourself hydrated, use paracetamol for fever, and try to rest in bed as much as you can.
• Take precautions to prevent the spread of illness by staying at home and wearing face masks and gloves if going outside.

Summary

H3N2v is a variant of the influenza virus that originally infects pigs but can spread to humans. The origin of the virus emerged in 2010 in the United States and subsequent outbreaks occurred, including a recent one in India in 2023. The transmission modes are explored, primarily through contact with infected pigs or their environments.

Symptoms of H3N2v closely resemble those of seasonal flu, making it challenging to differentiate without proper testing. However, the article highlights the importance of recognising the virus due to its potential severity, particularly in high-risk groups such as the elderly and immunocompromised individuals. Differentiating H3N2v from other illnesses like H1N1, influenza B or C, allergies, and pneumonia is discussed, emphasizing key distinguishing factors.

Preventive measures and actions to take if one suspects H3N2v infection are outlined, including staying at home, seeking medical advice, and monitoring symptoms closely. Prompt antiviral treatment is recommended, especially for high-risk individuals, and general precautions such as staying hydrated, resting, and preventing further spread through hygiene practices are encouraged. Overall, the article is a comprehensive guide for understanding, identifying, and managing H3N2v infections.

FAQs

Is there a vaccine for H3N2v infection?

Currently, there is no vaccine against H3N2v, and the seasonal flu vaccine will not protect against it. However, there is no H3N2v protection provided by the seasonal flu vaccine. Seasonal influenza viruses are defended against by seasonal flu vaccinations. Everybody six months of age and older is advised by the CDC to receive a seasonal flu shot every year.

What is the treatment for H3N2v?

Antiviral medications such as oseltamivir and zanamivir can be used to treat influenza infections in humans, including swine influenza, although there is evidence that some strains of influenza are more likely to develop resistance to oseltamivir.⁷

Whenever necessary, local infection specialists can provide expert advice on managing influenza for specific individuals.

What can I do to reduce my risk of getting H3N2v?

First of all, if you are one of the risk groups then you should seek advice on getting vaccinated as soon as it is available after consulting your physician. The CDC advises using seasonal vaccinations, even if their efficacy against H3N2v virus infections may be lower than that against seasonal influenza.⁸

Other simple measures such as adopting proper hand hygiene, wearing facemasks, and using a tissue to cover your mouth while coughing and sneezing can be very useful and important to break the cycle of the virus spreading. Nevertheless, if you know someone who is having flu-like symptoms then you should stay away and avoid contact. Last, but not least, avoid contacting pigs who have symptoms of flu and if you must be near them, wear gloves and a facemask. If you experience flu symptoms after contacting ill pigs, please contact your doctor.