People with HIV are at high risk from the new flu strain that the World Health Organization said is on the verge of a pandemic, the WHO said on Saturday.

The United Nations agency said people with immunodeficiency diseases - including the AIDS virus - will most likely be vulnerable to health complications from the H1N1 strain, as they are from regular seasonal flu, which kills between 250,000 and 500,000 people a year.

HIV and the new flu strain could also mix together in a dangerous way, as has occurred with HIV and tuberculosis, the WHO said in guidance for health workers on its website.

“Although there are inadequate data to predict the impact of a possible human influenza pandemic on HIV-affected populations, interactions between HIV/AIDS and A(H1N1) influenza could be significant,” it said.

“HIV-infected persons should be considered as a high risk and a priority population for preventive and therapeutic strategies against influenza including emerging influenza A(H1N1) virus infection,” it said.

The virus widely known as “swine flu” has been most severe in Mexico, where government authorities say it has killed more than 100 people, and caused more mild symptoms as it spread around the world to countries including the United States, Austria, Israel, New Zealand and South Korea.

Although the outbreak remains tiny in scale compared to other epidemics such as malaria, hepatitis, and meningitis, the WHO has raised its pandemic alert level to 5 out of 6 due to its rapid spread as well as the possibility that the flu could cause more devastation in poor and disease-prone communities.

Countries with high rates of HIV - most of which are in Africa - should work to ensure that vulnerable people get the drugs they need to fight off the flu infection, the WHO said.

Antiviral medicines such as Tamiflu and Relenza decrease the duration of virus excretion and the severity of illness when used for treatment of ill patients, and may also prevent illness when used for prophylaxis.

“Patients at higher risk for complications of influenza including those with HIV infection should be among those prioritized for antiviral treatment with oseltamivir or zanamivir which shortens illness duration and severity in seasonal influenza,” the WHO guidance read.

It is best if people infected with the flu strain start to take the antivirals within 48 hours of the onset of symptoms, according to the WHO. There are no known problems with taking those drugs alongside the anti-retrovirals that HIV patients take to suppress their virus.

According to WHO estimates, there are 33 million people infected with immune-weakening HIV worldwide.

By Laura MacInnis
GENEVA (Reuters)