Experts believe that relying too heavily on a specific medication during an outbreak is a significant mistake.
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Relenza |
Recently, the H5N1 avian influenza virus, which has killed 60 people in Southeast Asia, was identified as the cause of the deaths of over 1,000 poultry in Turkey.
British experts have also analyzed samples taken from the carcasses of wild birds sent from Romania and concluded that H5N1 was responsible for the deaths of these birds. In both countries, thousands of poultry have been culled to prevent the further spread of the virus.
During a Senate inquiry into the risk of an avian influenza outbreak in the UK, Mr. Jan Slingenberg, an official from the Food and Agriculture Organization (FAO), stated that “the H5N1 avian influenza virus has now infiltrated Europe.”
In response, countries have ramped up their reserves of Tamiflu, the primary antiviral medication recommended by the World Health Organization for avian influenza. Turkey has asked Swiss pharmaceutical company Roche Holding AG to supply 500,000 doses immediately. Romania has also reported that it is stockpiling tens of thousands of doses of this medication. This stockpile will be used in case the H5N1 virus undergoes genetic mutation and becomes capable of human-to-human transmission.
Tamiflu is currently an effective treatment against H5N1 in humans, but a new study published in Nature indicates that the situation may change. An analysis of the H5N1 virus from a Vietnamese patient treated with Tamiflu showed that some viruses had developed partial resistance to this medication. The patient recovered after being treated with high doses of Tamiflu, and the emergence of drug-resistant viruses is not surprising. However, the study indicates that this drug resistance could become a serious issue that scientists need to examine more closely.
Mr. Yoshihiro Kawaoka, a virologist from the University of Tokyo in Japan and the lead researcher, stated: “We do not know how frequently this type of genetic mutation occurs. We are too dependent on Tamiflu; we need additional medications.”
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| More new medications are needed to guard against H5N1 drug resistance |
According to him, ideally, countries should continue to stockpile Tamiflu. However, there should be multiple other medications available to combat the avian influenza virus as a secondary line of defense. In addition to Tamiflu, another medication known to be effective against drug-resistant viruses is Relenza. However, very few countries currently stockpile this medication. Only Germany has a large stockpile, with some other European countries and the United States having a small amount.
Mr. Albert Osterhaus, a virologist at Erasmus Medical Center in Rotterdam, Netherlands, also agreed that pharmaceutical companies have been slow to develop antiviral medications that can treat avian influenza. He noted that while Relenza could serve as a good alternative to Tamiflu, it also has limitations. He stated, “Tamiflu can be stockpiled in large quantities and for extended periods, but Relenza is difficult to store.” This medication is administered via an inhaler, making it unsuitable for young children and severely ill patients. However, both Mr. Kawaoka and Mr. Osterhaus agree that additional medications need to be developed.
Mr. James Robertson, a virologist at the UK National Institute for Biological Standards and Control, concurred that H5N1 viruses resistant to Tamiflu are likely to become a major issue. “This will happen. Once you begin using Tamiflu in large quantities, drug resistance will emerge.”
However, he added that recent studies have found that partially drug-resistant viruses in this case are not as dangerous as typical H5N1 viruses. He explained: “The drug-resistant viruses seem to be weaker; they do not replicate well.” Yet, a drug-resistant virus could undergo a second mutation, which could make them stronger. Improper use of medication could also lead to the emergence of drug-resistant viruses. Mr. Kawaoka noted that Tamiflu can relieve avian influenza symptoms in humans within two days, leading people to stop taking the medication; this can facilitate the development of drug-resistant viruses. He stated: “To reduce the chances of drug resistance, a full five-day treatment course should be completed.”
Nature, People’s Daily
