Quick Guide To H1N1 Flu Virus and Symptom List

The flu virus and associated symptoms of infection have been a focus of much media coverage over the past several months. It started, in April 2009, when a new strain of the H1N1 swine flu virus was isolated near the Mexican-US border. There are few studies available that investigate the diagnosis of H1N1 2009 symptom by symptom. But these are the facts, we know now that may help. We anticipate more information from doctors and scientists at the CDC, in the coming months.

Why was this strain thought to be so important?

The new H1N1 2009 flu strain gained much attention when experts discovered it carried genes similar to the 1918 swine flu, which caused a world wide pandemic with millions of deaths. On June 11, 2009, the World Health Organization declared this as the first pandemic of the 21st century to prevent another catastrophic world disaster. By June 12, 2009, this virus had already spread to 74 countries, with over 29,000 infected people. It already accounted for a loss of 145 patients who died.

What were the symptoms of H1N1 2009 in the first cases?

To gather data on flu prevention, health care professionals studied 642 confirmed people with H1N1 2009 virus infections, in the US. The diagnosis in these individuals was made using sensitive immune based techniques and nasal secretions. These people ranged in age from 3 years to 81 years old.

Typically the symptoms associated with H1N1 2009 were similar to seasonal influenza and other respiratory viral conditions. Seasonal influenza is characteristically an illness consisting of a low grade fever, sore throat, cough, rhinorrhea (runny nose), headache and myalgias (muscle aches). Although the symptoms of respiratory viral infections such as the common cold and seasonal flu are similar; the list below characterizes our early understanding of the symptom distribution among those infected with H1N1 2009.

Quick 5 Symptom List:

• 1. 94% presented with fever
• 2. 92 % were coughing
• 3. 66% had a sore throat
• 4. 25 % had diarrhea
• 5. 25% had vomiting

H1N1 2009 causes symptoms similar to the seasonal flu. However, 25 percent of those infected also experience vomiting and diarrhea, unlike the seasonal flu. Information on sneezing, sinusitis, bronchitis and other disease related complications was not available.

Approximately 9% were thought to require hospitalization with severe systemic flu complications. People who were admitted to hospital had high rates of pneumonia (approximately 50%). Keep in mind that this data was derived from a very small sample of patients. Due to the severity of the illness in some patients, intensive care treatment was required.

Who is susceptible to H1N1 2009?

Younger individuals were found to be more susceptible to this strain of flu virus. Of these cases 60% were less than 18 years old, 40% were between 10-18 years and only 5% of cases were over 51 years old. The child appeared more susceptible than the adult to H1N1 2009.

Why are older individuals less susceptible to H1N1

It was felt that older patients had cross protection from a previous flu infection, in life. Cross reacting antibodies to the H1N1 were found in:

1. 6-9% of those aged 18-64 years

2. 33% of those aged greater than 60 years.

Scientists concluded that children and young adults were more susceptible because 60% of initial patients were? 18 years. This delay of transmission to older people may also be explained by the fact that the young and old live in differences in social networks. Transmission occurs faster in social networks of younger individuals. Another possibility that may explain this difference in susceptibility to H1N1 2009 is that elderly persons may have had some level of cross- protection from pre-existing antibodies against other influenza A (H1N1) viruses. These theories require further study. Apparently, vaccinations to previous influenza strains may not afford prevent infection by H1N1 2009.

Overall, most confirmed cases of H1N1 2009 viral infections have been typically self-limited, uncomplicated febrile respiratory illnesses. The symptoms are similar to those of seasonal influenza (a cough, a sore throat, rhinorrhea, headache, and myalgia). Approximately 38% of cases have also developed vomiting or diarrhea, neither of which is typical of seasonal influenza. Some infected individual’s develop severe illness and required hospitalization, and few patients die.

For effective prevention learn about the K.I.S.S. Method and consult your family doctor.