Tamiflu Resistance in H1N1 Flu Virus [Updated]

The World Health Organization has raised its pandemic alert for swine flu by one level to phase 4, two steps short of declaring a full-blown pandemic. WHO says the phase 4 alert means sustained human-to-human transmission is causing outbreaks in at least one country.

Current WHO phase of pandemic alert

The data on the current flu season, 2008-2009 is obviously not complete since the season is not yet finished, but an analysis on that which has been gathered so far shows that Tamiflu resistance in H1N1 type A strains continue at a high level. Up to 19 February 2009, Tamiflu resistance was found in 264 of 268 (98.5 per cent) of the H1N1 type A viruses tested by the CDC.

The authors wrote that:

“The emergence of oseltamivir resistance has highlighted the need for the development of new antiviral drugs and rapid diagnostic tests that determine viral subtype or resistance, as well as improved representativeness and timeliness of national influenza surveillance for antiviral resistance.”

In December last year the CDC issued draft guidelines for the use of antiviral flu medications in line with what they found after analyzing the data coming in for the current season. They recommended that doctors and other health professionals:

“Consider the results of patient testing and local influenza surveillance data on circulating types and subtypes of influenza viruses in deciding whether oseltamivir [tamiflu] alone could be used. These guidelines provide options, including preferential use of [the anti-viral drug] zanamivir or a combination of oseltamivir and [the anti-viral drug] rimantadine, which might be more appropriate in treating patients who might have influenza caused by an oseltamivir-resistant virus.”

Human cases of swine influenza A (H1N1) virus infection have been identified in the United States. Human cases of swine influenza A (H1N1) virus infection also have been identified internationally.

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 the World Health Organization. CDC has activated its Emergency Operations Center to coordinate this investigation.

Laboratory testing has found the swine influenza A (H1N1) virus susceptible to the prescription antiviral drugs oseltamivir and zanamivir and has issued interim guidance for the use of these drugs to treat and prevent infection with swine influenza viruses.

[NOTE: European specialists have voiced their opinion that this virus quickly adapts and have great concern to forms of resistant strains H1N1-virus to Tamiflu medication – Oui]  

Checks at air and sea ports stepped up; public urged to be on guard.

(Straits Times) – Asian nations have started taking measures, including quarantines and screening passengers at airports, to combat the the threat of a deadly swine flu which has killed 103 in in Mexico and stoked fears of a global epidemic as new cases cropped up in the United States and Canada.

Tokyo’s Narita airport installed a thermographic imaging device to test the temperatures of passengers arriving from Mexico.

Hong Kong and Taiwan said visitors who came back from flu-affected areas with fevers would be quarantined. China said anyone experiencing flu-like symptoms within two weeks of arrival from an affected area had to report to authorities. A Russian health agency said any passenger from North America running a fever would be quarantined until the cause of the fever is determined.

Symptoms of the flu-like illness include a fever of more than 37.8 deg C, body aches, coughing, a sore throat, respiratory congestion and, in some cases, vomiting and diarrhoea.