More dangerous, oseltamivir-resistant H1N1 swine flu strain reported in EU, US

A more dangerous strain of H1N1 swine flu virus is reportedly emerging.

H1N1 swine flu virus strain could have mutated into a new form which is capable of causing a more severe disease and also resistant to the available drugs including oseltamivir and zanamivir, reports said.

The new mutated strain of the H1N1 virus is being investigated by by European and U.S. public health officials.

Several cases of H1N1 infections showing resistance to the lead drug oseltamivir which is marketed under the brand name Tamiflu have been reported in European and US hospitals.

Five patients at a hospital in Wales had H1N1 swine flu that resisted treatment with Tamiflu, and three more infections were being analyzed, the U.K. Health Protection Agency said.

All the five patients had other medical conditions making them more vulnerable to flu. Two have been discharged, and one is in intensive care, while the other two remain in the hospital.

“The Tamiflu-resistant virus has emerged in a group of particularly vulnerable individuals,” a Department of Health spokesman said.

These patients are known to be at increased risk of developing resistance to the drug. The health authority’s strategy to offer antivirals to all patients with swine flu is the right one — to help prevent complications and reduce the severity of the illness, he commented.

The Norwegian Institute of Public Health reported another H1N1 mutation, found in three patients, including the first two to die from H1N1 in Norway.

H1N1 swine flu virus mutation has been found in a few previous cases in April and in widely scattered countries, The Wall Street Journal reported.

The World Health Organization in Geneva said H1N1 vaccine and antiviral drugs used against H1N1 are effective with the mutation.

Another, four patients were reportedly shown resistance to Tamiflu in a North Carolina hospital.

Health authorities and experts are monitoring the new clusters closely, according to health officials from the U.S. Centers for Disease Control and Prevention and the World Health Organization.

H1N1 influenza cases went down recently in the U.S. and was widespread in 43 states compared with 46 states the week earlier, the CDC officials said.

Since swine flu was identified in April, there have been 57 U.S. cases of Tamiflu resistance and sporadic reports of mutations similar to those in Norway.

H1N1 infection also known as swine flu, has already infected about 22 million people in the U.S. and killed 3,900 people from April to Oct. 17, according to the CDC’s most recent estimate.

H1N1 swine flu has killed at least 6,770 people worldwide, according to an estimate from the Geneva-based WHO.

WHO no longer keeps an up-to-date numbers of global cases of H1N1 infections.

Norway has an estimated 700,000 infections, with 21 reported deaths.

The swine flu mutation discovered in Norway is difficult to pass from person to person, said David Mercer, acting head of the communicable diseases unit of the WHO’s European region, and Geir Stene-Larsen, the head of the Oslo-based Institute of Public Health. The mutation was found in 3 of 70 patients tested, the institute said.

It is most likely that H1N1 virus’ capability to mutate is not just specific to Norway, it will occur in other countries as well, experts said.
Tamiflu, whose generic name is oseltamivir, is one of two main antivirals in the arsenal against swine flu as the world awaits the widespread availability of a vaccine against the disease.

Roche’s studies concluded that 0.32 percent of adults and 4 percent of children who took oseltamivir (Tamiflu) developed resistance.

The 13 cases were scattered around the world in Europe, the United States and Asia.

The oseltamivir resistant variety also produces only mild symptoms as it is typical widespread version of the H1n1 virus.

Roche was not quite certain why the 13 patients developed the resistance while taking the drug. Possibly, patients who were taking inadequate doses – only half a dose – of the prescribed dosage of the drug were developing oseltamivir resistance, Roche said.

“If they were actually infected with the virus, the dosage of the drug may have been too low,” Roche sources were quoted as saying in media reports.

The Tamiflu supplier was also taking a closer view on H1n1 virus’ interaction with oseltamivir.

Oseltamivir can be taken as a preventive at the half-dose strength if taken for up to six weeks.

But in case of the patients presenting with symptoms, medical practitioners should prescribe the full treatment dose and not the prevention dose which half-doze strength.

Denmark, Japan, Hong Kong, Canada & Thailand are among the nations that reported cases of oseltamivir-rasistant strains of H1N1 virus.

Among the Asian countries, Japan has confirmed two cases of A/H1N1 resistance to oseltamivir (Tamiflu).

Thailand, China, Singapore reportrd atleast one case of oseltamivir resistance.
In Hong Kong, Tamiflu-resistant swine flu was found in a teenager who did not take Tamiflu.

Influenza virus shares similar features as HIV-1 including high replication rates in many hosts, and the generation of large numbers of viral mutants. The difference with influenza is that a vaccine is available.

However, antiviral compounds like osetamivir (Tamiflu) and Zanamavir (Relenza) – an alternative inhalable anti-viral from GlaxoSmithKline–should only be used with caution, experts alert.