June 30, 2009
Drug-Resistant Flu Strain Turns Up In Denmark but Doesn't Last Long
By DONALD G. McNEIL Jr.
The first case of swine flu resistant to the antiviral drug Tamiflu has been found in Denmark, according to Danish health officials.
The patient appears to have recovered without infecting anyone else, and experts said the recent history of Tamiflu resistance made it unlikely that the short-lived Danish strain would have been good at spreading to others.
An executive of Roche, the Swiss maker of Tamiflu, held a telephone news conference to describe the progress of the Danish patient, who apparently developed the resistant strain while being protectively treated with a low Tamiflu dose because a close contact had the swine flu. Doctors switched treatment to a different but related drug, Relenza, and the patient recovered.
In the past, Tamiflu-resistant strains of the seasonal flu have been found in Japan, which has used more than half the world's supply of the drug each year. But those strains were weak and did not spread. A Tamiflu-resistant strain of the H5N1 bird flu was also isolated from a Vietnamese patient being treated with low-dose Tamiflu in 2005, but it also died out.
Tamiflu resistance that did spread in seasonal flu emerged last year from a spontaneous mutation known as H274Y on the N gene. The mutant strain dominated the seasonal H1N1 flu during the past flu season in the United States, before swine flu was discovered in Mexico.
Virologists fear swine flu will soon pick up resistance by merging with seasonal H1N1 flu, perhaps in the Southern Hemisphere, where the flu season is just beginning.
Jun 30, '09
dr. niman continues to defend his position. it is too soon to say if he is right. only time will tell, but in the meantime we will be watching for these expected changes to occur. remember that tamiflu drug resistant strains occurred in people infected with seasonal flu, h1n1, that were not even taking this drug.
the strains were already resistant.
i corrected his typos because they drive me nuts.
Quote from www.flutrackers.com
originally posted by mamabird
please carefully read the ecdc assessment of the danish resistant virus, appended to their daily swine flu update:
this has been categorized as a secondary resistant virus due to the use of tamiflu administered to the patient. it is not a primary virus, ie., one that was acquired from another infected person. this is based on the isolation of the viruses in the cluster of contacts around the danish woman. none of those sequences revealed the na mutation causing tamiflu resistance.
the report is rather vague on who and how many were in the cluster, as well as how hard they looked. if the overseas traveler had a mixture, the tamiflu may have selected h274y in the patient who developed symptoms after being on tamiflu for 5 days, while the other isolates may have been collected prior to treatment, keeping the resistant sequence at a low level.
this is somewhat like the data for s227n in h5n1 in turkey. the index case had s227n, but his sister didn't. webridge said the s227n developed in the index case but subsequently two more sequences were release[d] from others in turkey (they would [not] say from who) and one had s227n while the other didn't. in all likelihood all four had s227n and the published sequence represented what grew out in cluture. of the four sequences two had s227n and two didn't.
the same thing happened in the sars outbreak. all of the polymorphisms really originated with the index case, but many were absent from the sequence from the index case and many jumped contacts
i will still predict that h274y will soon start appearing in swine h1n1, including patients who are not taking tamiflu.
notice that this group still can't explain how h274y in seasonal flu managed to jump from genetic background to genetic background in the absence of tamiflu and just calls it "complex".
Quote from www.flutrackers.com
originally posted by mamabird
i guess we can expect the release of all the related danish genetic sequences in very short order, expecially since this case apparently resolved itself earlier in the month.
the tracing will likely be more informative than the sequence, unless the sequence has mixed signals. it is of note that this incident apparently happened some time ago, but to date there is a total of one sequence, collected in april, that is public.
Last edit by indigo girl on Jun 30, '09
Jul 2, '09
Japan Finds Tamiflu Resistant Case Of H1N1
WHO must have known about this when the Danish case was made public, surely.
Quote from afludiary.blogspot.com
A second case of Tamiflu resistant H1N1- this time from Japan - has made the news. On Monday,the media reported the first known case - in Denmark.
What is a bit surprising is that this case occurred sometime in May, and we are just now learning about it.
Last edit by indigo girl on Jul 2, '09
Jul 3, '09
Hong Kong: Detection of human swine influenza virus resistant to Tamiflu
This is the third case we are finding out about. Notice the dates of discovery of all of these cases.
This article makes note of the other two cases,"Denmark and possibly Japan."There is no possibly. The Japanese case is documented. This latest case flew in from San Francisco, and was never on Tamiflu, but she already had a resistant strain of the virus.
None of these sequences are available for viewing, btw, so none but a few select scientists who are not talking, can say if H274Y appears in any of these viruses.
Quote from www.flutrackers.com
A spokesman for the Department of Health (DH) said the department's Public Health Laboratory Services Branch (PHLSB) today (July 3) detected a strain of human swine influenza (HSI) virus which was resistant to oseltamivir (Tamiflu).
The virus was identified during PHLSB's routine sensitivity test of HSI virus to oseltamivir and zanamivir, the spokesman said.
"This is the first time Tamiflu resistance in HSI virus found in Hong Kong," he said, adding that similar cases were also reported in Denmark and possibly Japan.
"Tests showed that this strain is sensitive to zanamivir (Relenza)," he said.
The virus was isolated from the specimen taken from a 16-year-old girl coming from San Francisco. She was intercepted by Port Health Office at the Hong Kong International Airport on June 11 upon arrival. The girl was then admitted to Queen Mary Hospital for isolation. She was tested positive to HSI but opted not to take tamiflu. She had mild symptoms and was eventually discharged upon recovery on June 18.
The spokesman noted that PHLSB conducted routine sensitivity tests on specimens taken from confirmed HSI patients.
"This is the only Tamiflu-resistant strain so far among some 200 HSI samples tested in Hong Kong. Further tests are underway," he said.
Hong Kong has maintained an antiviral stockpile of both Tamiflu and Relenza.
The case will be reported to the World Health Organization (WHO), the spokesman said. He reiterated that Hong Kong had an intensive influenza surveillance system on antiviral resistant influenza viruses.
"We will closely liaise with WHO and overseas health authorities and monitor the global development of antiviral resistant HSI virus," he said.
Last edit by indigo girl on Jul 3, '09
Jul 4, '09
Possible case of “resistant” A (H1N1) virus
This is the 3rd case of a person who had flown in from the states, demonstrating Tamiflu resistance.
Quote from www.thehindu.com
The State health authorities have been asked to send a blood sample of the infected person to the National Institute of Virology (NIV), Pune.
The patient, a man who had flown in from the U.S. in the third week of June, had tested positive along with his wife.
They were quarantined at the Communicable Diseases Hospital (CDH) here and started on a course of Tamiflu. “This was through the Directly Observed Treatment Short-course method, which means we know he took every tablet and did not miss out on even a single dose. Missing on doses can lead to resistance, but that is not the case with this patient,” Director of Public Health S. Elango said.
While his wife recovered and tested negative for A (H1N1) after about 10 days, the husband continued to test positive even after the treatment was completed.
Though he showed no symptoms, his tests kept coming back positive, Dr. Elango said.
“This is a case to be studied, definitely. The virus should not remain in his blood after the treatment. It is possible that it is a mutation of the virus. I have instructed the officials at the NIV to sequence the strain [from the samples] as soon as possible. Once we have that, we can have the alternative drugs to treat the patient,” Dr. Katoch explained.
He said the patient at the CDH could be treated on recommended doses of the drug ‘Relenza’ available in India.
When told that the patient was anxious to go home, Dr. Katoch categorically said that he could not be discharged as long as he continued to test positive, even if he was not symptomatic.
“He is certainly a carrier and can spread the virus to members of his family, and thereby take it into the community. That should not be allowed to happen. Indigenous transmission of the virus from this person will lead to a huge public health problem,” Dr. Katoch said.
The issue would be sorted out as soon as the sequence was drawn up. “That way we will also be ready for any future occurrences.”
[hat tip Avian Flu Diary]
Last edit by indigo girl on Jul 4, '09