CDC Issues Avian Influenza A Advisory

The first confirmed case of avian influenza A (H5N1) in North America this year has led the CDC to issue a health advisory reminding physicians about the symptoms and treatment of influenza A viral infections.

Although this is an isolated case with no sign of further spread, the potential exists for more novel flu cases imported into North America. Therefore, the CDC urged clinicians to consider the possibility of the infection among recent travelers presenting with severe respiratory illness.

The health advisory comes soon after the report of the first confirmed case of H5N1 in North America on January 8, 2014, by the Public Health Agency of Canada. The Canadian patient, who had recently traveled to Beijing, China, was hospitalized on New Year’s Day and died 2 days later.

To date, no cases of human infection with H5N1 viruses have been reported in the United States.

The H5N1 virus is rarely transmitted from person to person, but the CDC used this case as a reminder that “novel influenza A viruses, including the H5N1 virus, can infect and cause severe respiratory illness in humans. The clinical presentation of human infection with avian influenza A viruses varies considerably. Most reports of H5N1 in humans, however, have described severe illness, including fulminant pneumonia leading to respiratory failure, acute respiratory distress syndrome, and death. Other reported H5N1 complications include encephalitis, septic shock, and multi-organ failure.”

The health advisory suggested that clinicians consider the possibility of H5N1 virus infection among those exhibiting symptoms of severe respiratory illness who have recently traveled (within 10 days of illness onset) to areas where human cases of H5N1 virus infection have been detected or where the viruses are known to be circulating in animals.

“Rapid detection and characterization of novel influenza A viruses remain critical components of national efforts to prevent further cases, evaluate clinical illness associated with them, and assess any ability for these viruses to spread among humans,” stated the health advisory.

The CDC urges state health departments to investigate potential human cases of H5N1 and notify the agency within 24 hours of identifying a probably or confirmed case. Patients meeting clinical and exposure criteria should be tested for H5N1.

Treatment and Chemoprophylaxis

Patients hospitalized with suspected novel influenza A virus infections, including H5N1, should receive empiric treatment with oseltamivir (Tamiflu) as soon as possible. Early initiation of treatment provides a more optimal clinical response, although treatment of moderate, severe, or progressive disease begun after 48 hours of the onset of symptoms may still provide clinical benefit.

Those who are suspected of having been exposed to H5N1 should be monitored daily for 10 days for fever and respiratory symptoms. Antiviral chemoprophylaxis should be provided to close contacts, according to risk of exposure.

The CDC offers additional guidance on antiviral treatment of patients under investigation for H5N1 virus infection with antiviral medications, as well as guidance on antiviral chemoprophylaxis of exposed contacts. Guidance on testing, treatment, and infection control will be updated by the CDC as more information becomes available.