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Influenza A/Brazil/78(H1N1) infection in the elderly
Abstract:
Although influenza A/H1N1 virus has caused both sporadic illness and epidemics throughout the world, there have been few cases and no outbreaks reported in older persons. Using a surveillance program for detection of viral respiratory tract illness, we documented an outbreak of influenza (A/Brazil/78(H1N1) infection in one floor of a chronic disease hospital. We prospectively studied all 32 patients and 16 personnel on that floor. Infection was proved in 11 subjects by serology and/or virus isolation, including 9 patients (median age, 84 yr) and 2 personnel (36 and 58 yr of age), for attack rates of 28% and 12.5%, respectively. Six patients had fever, 38 degrees C to 39 degrees C, lasting for 1 to 5 days (median, 4), and/or respiratory and constitutional symptoms lasting for 2 to 17 days (median, 13). Bacterial pneumonia occurred in 1 patient 12 days after the onset of upper respiratory tract illness. Risk factors for acquisition of infection in patients included a nonvaccinated state (p = 0.03) and a preinfection antibody titer of less than or equal to 32 (p = 0.02). These findings indicate that older persons are at risk for infection with influenza A/H1N1 virus, which may also cause outbreaks of respiratory illness in the elderly institutionalized population similar to other influenza viruses.
Insights
Influenza A/H1N1 outbreaks can affect older individuals in chronic care facilities. Vaccination and adequate antibody titers are crucial for preventing infection in this vulnerable population.
Area of Science:
- Virology
- Epidemiology
- Geriatrics
Background:
- Influenza A/H1N1 virus is a known cause of sporadic illness and epidemics globally.
- Few cases and no outbreaks of influenza A/H1N1 have been reported in older populations.
- The elderly, particularly those in institutional settings, may be susceptible to influenza A/H1N1.
Purpose of the Study:
- To document an outbreak of influenza A/H1N1 infection in a chronic disease hospital.
- To investigate the clinical characteristics and risk factors associated with influenza A/H1N1 infection in elderly patients and hospital personnel.
- To determine the susceptibility of older persons to influenza A/H1N1 virus.
Main Methods:
- A surveillance program for viral respiratory tract illness was utilized.
- A prospective study was conducted on all 32 patients and 16 personnel on one floor of a chronic disease hospital.
- Infection was confirmed through serology and/or virus isolation.
Main Results:
- An outbreak of influenza A/Brazil/78(H1N1) infection occurred on one floor of a chronic disease hospital.
- Eleven individuals (9 patients, 2 personnel) were confirmed infected.
- Patient attack rate was 28% (9/32), with a median age of 84 years. Personnel attack rate was 12.5% (2/16).
- Symptoms included fever and respiratory/constitutional issues. One patient developed bacterial pneumonia.
- Risk factors for patient infection included non-vaccination (p = 0.03) and low preinfection antibody titers (p = 0.02).
Conclusions:
- Older persons are at risk for influenza A/H1N1 virus infection.
- Influenza A/H1N1 can cause outbreaks of respiratory illness in institutionalized elderly populations.
- Findings suggest that influenza A/H1N1 may behave similarly to other influenza viruses in the elderly.