Your Family Physician

May 12, 2009 — The World Health Organization (WHO) is developing clinical management guidelines for the use of antivirals in the treatment of the novel influenza A (H1N1) strain, and both WHO and the Centers for Disease Control and Prevention (CDC) are advising against overuse except in higher-risk cases, the agencies announced today.

Dr. Nikki Shindo, medical officer in the WHO Global Influenza Programme and leader of the clinical team of the WHO response to the H1N1 influenza outbreak, noted during a media briefing that the new guidance will highlight "the fact that most of the patients will not require hospitalization or antiviral therapy."

The latest WHO estimate of confirmed H1N1 influenza cases is 5251 cases in 30 countries.

According to Dr. Shindo, simple supportive therapy, such as antipyretics and hydration are "sufficient" for many cases. Other supportive therapies include oxygen and antibiotics. The guidelines recommend against using aspirin due to the risk of Reye's syndrome.

"We have seen a spectrum of disease from mild, typically what you call influenza-like illness...to very severe form of this disease, this is pneumonia sometimes requiring mechanical ventilation," she said. Many of the severe illnesses and deaths occurred in persons with underlying chronic medical conditions, but it is still unknown why many severe cases were also occurring in healthy adults and children, she said.

Dr. Shindo pointed out that European countries have been using antivirals aggressively compared with countries such as Mexico and the United States, and while it remains to be confirmed, this "could be the reason why we are seeing less severe cases in European countries." She noted that in seasonal influenza, emergence of resistance does not seem to be directly related to use of antivirals in a given country.

As of today, the CDC is reporting about 3600 probable and confirmed cases in 46 states and Washington, DC, with 3002 confirmed cases in 44 states and Washington, DC, with 3 reported fatalities. A total of 116 hospitalizations have been reported. Currently, 29 states are doing their own confirmatory testing for the novel H1N1 influenza strain.

Pregnant Women at Higher Risk for Complications

Today's media briefing at the CDC was led by Anne Schuchat, MD, the interim deputy director for Science and Public Health Program, and focused on the effects of H1N1 influenza on pregnant women.

"Pregnant women are at higher risk of complications with influenza...and we are also seeing some severe complications among pregnant women in this year's novel H1N1 virus problem," Dr. Schuchat said. "We have about 20 cases under investigation" in pregnant women.

According to Dr. Schuchat, a few of the pregnant patients have had severe complications, including 1 fatality. Influenza can cause worse complications in pregnancy, including pneumonia, and dehydration and problems for newborns.

"We think it's very important when doctors are caring for pregnant women who they suspect may have influenza, that they issue prompt treatment with antiviral medicines," she said. "Sometimes physicians are reluctant to treat pregnant women with medicines and pregnant women are reluctant to take medicines..." but "the benefits of using antiviral drugs to treat influenza in a pregnant woman outweigh the theoretical concerns about the drug."

Oseltamivir or zanamivir can both be used in pregnancy.

It remains unclear how the virus will spread during the fall, Dr. Schuchat told Medscape Infectious Diseases during the press conference. The simultaneous circulation of the highly transmissible novel H1N1 strain, the very virulent H5N1 avian strain, and the oseltamivir-resistant H1N1 seasonal influenza strain is an "unfortunate circumstance," she added.

Source : http://www.medscape.com/viewarticle/702730?sssdmh=dm1.470812&src=nldne