New subtype of influenza virus - Swine influenza

The Centers for Disease Control and Prevention (CDC) report laboratory-confirmed human cases of swine influenza A/H1N1. Human cases of swine influenza A/H1N1 virus infection also have been identified internationally.

Based on preliminary testing, the virus is being described as a new subtype of A/H1N1 not previously detected in swine or humans.

Laboratory testing has found the swine influenza A/H1N1 virus is susceptible to the prescription antiviral drugs oseltamivir and zanamivir. According to Anne Schuchat, MD, the CDC's Interim Deputy Director for Science and Public Health Program, treatment should begin within 48 hours of onset. Vaccine development is in process, but it will take several months to prepare a vaccine.

CDC has issued interim recommendations for diagnostic testing and antiviral use, but local and state circumstances may vary and individual protocols may be put in place.

The CDC also has prepared interim guidance on how to care for people who are sick and interim guidance on the use of face masks in a community setting where spread of this swine flu virus has been detected. This is a rapidly evolving situation and CDC will provide new information as it becomes available.

The World Health Organization (WHO) reports that the government of Mexico also has reported several laboratory-confirmed cases of swine influenza A/H1N1. In a media briefing today, the CDC confirmed several swine influenza-related deaths as well. Investigation is continuing to clarify the spread and severity of the disease in Mexico. Suspect clinical cases have been reported in 19 of the country's 32 states.

Investigations are ongoing to determine the source of the infection and whether additional people have been infected with swine influenza viruses.

CDC is working very closely with officials in states where human cases of swine influenza A/H1N1 have been identified, as well as with health officials in Mexico, Canada, and WHO. This includes deploying staff domestically and internationally to provide guidance and technical support. CDC has activated its Emergency Operations Center to coordinate this investigation.

WHO and the Global Alert and Response Network (GOARN) are sending experts to Mexico to work with health authorities. WHO and its partners are actively investigating reports of suspect cases in other Member States as they occur and are supporting field epidemiology activities, laboratory diagnosis and clinical management.