A strain of human swine flu found in Hong Kong was detected to be resistant to Tamiflu, the sixth such case in the city, the Department of Health said in a statement today.

A department spokesman said the virus was identified during a routine sensitivity test to antiviral drugs. The virus specimen was taken from a three-year-old boy who hadn’t been prescribed Tamiflu, the statement said.

via Hong Kong Finds Sixth Tamiflu-Resistant Swine Flu Strain – BusinessWeek.

A total of 171 campers, 48 camp counsellors and 27 camp staff were involved. Three campers tested positive for H1N1 during one of the camp’s two-week sessions.

These received oseltamivir and were immediately isolated and sent home. All campers and counsellors in the infected child’s adjoining cabins took oseltamivir prophylactically for 10 days. In addition, alcohol-based hand sanitisers were provided throughout the camp; counsellors also received advice about the spread of influenza and its prevention.

All surfaces in communal areas were also sprayed or wiped down every day. No additional campers, counsellors or staff members became ill during the session and no campers tested positive for H1N1 after returning home. The three infected campers constituted an attack rate – the percentage of individuals who get sick out of the total population – of 1.8 per cent.

Some 78 per cent of the staff and counsellors and about 31 per cent of campers experienced one or more adverse events, such as nausea, vomiting or headache, from the medication. However, none of the adverse events resulted in discontinuation of the therapy.

more via Irish Medical Times | Clinical TImes | Reducing spread of H1N1 among children.

Analysis of a phylogenetic tree for NAs in seasonal H1N1 viruses from 2006 and later led to identification of two candidate mutations (V234M and R222Q) that could have permitted the occurrence of the H274Y mutation without substantial loss of viral fitness among naturally circulating viruses. Additional studies verified that both of these mutations restored both total NA enzymatic activity and replication ability.

Both the H274Y mutation and the V234M and R222Q mutations appear to mediate their effects by altering interactions among amino acids in the NA polypeptide chains. In the former case, H274Y prevents a flipping motion of the E276 side chain that is necessary for oseltamivir to bind to NA (8-9, reviewed in 10). The V234M and R222Q mutations are hypothesized to counter negative effects on folding or stability of NA by H274Y (1). Thus, in this instance, evolutionary biology, virology, and pharmacology grade into biophysics.

Much more medico speak via The Evolution & Medicine Review » Blog Archive » Amino Acid Gymnastics and the Evolution of Influenza Virus Resistance to Oseltamivir.

The H1N1 virus has undergone a slight genetic mutation and its effect on patients has also changed. But patients are still responding to anti-viral drug Tamiflu.

“Unlike last year, swine flu patients don’t have high fever these days. Severe sore throat and backache are the most prominent symptoms now,” said Dr G.T. Ambe, Brihanmumbai Municipal Corporation’s executive health officer.

He added that Tamiflu and the vaccine are still “very effective.”

via H1N1 virus has mutated- Hindustan Times.

Long-term care facilities are vulnerable to outbreaks of influenza. This report describes the response to such an outbreak in a long-term care facility for severely handicapped children and adults near Ljubljana, Slovenia, in March and April 2009. Of the 23 residents who lived in a unit of the facility, 10 fell ill with fever (≥37.5 ºC) during a period of nine days. Probable and confirmed cases were residents who developed a fever after 24 March 2009. Respiratory symptoms were not included in the case definitions as some residents were unable to describe their symptoms due to their mental and/or physical impairment. Epidemiological data were collected and throat and nasal swabs taken. Influenza A virus was identified (without subtyping) and treatment with oseltamivir was given to patients with fever of no more than 48 hours’ duration. Oseltamivir was also given prophylactically to healthy residents and staff. Rigorous adherence to standard and droplet precautions was recommended by the regional institute of public health. Two days after respiratory and standard precautions have been strengthened, four more residents became ill. Viral subtyping showed that 12 of the 23 residents were infected with influenza virus A(H1N1); one had an influenza B virus infection. Of the 12 confirmed influenza A cases, 10 had been vaccinated with the seasonal influenza vaccine. Follow-up swabs were taken and were found to be still positive for influenza A virus in 6 of the 12 confirmed cases more then a week after illness onset. The virus was resistant to oseltamivir and susceptible to zanamivir. This influenza outbreak demonstrates the need for rapid typing and subtyping of influenza viruses for accurate diagnosis, treatment and chemoprophylaxis in special settings.

via A TIME’S MEMORY: Influenza A(H1N1) outbreak in a long-term care facility for severely handicapped residents, Slovenia, March–April 2009 (Euro Surveill., edited).

n November 2009, a healthy 2-year-old boy was admitted to the pediatric intensive care unit at the Western Galilee Hospital in Nahariya, Israel, after he had been hit by a car. One day before the accident, he had exhibited fever and cough (for which he had been treated with acetaminoiphen). His 4-year-old brother had recovered recently from an influenza-like illness without antiviral treatment.

The above comments are from the upcoming paper entitled “Community-acquired Oseltamivir-Resistant Pandemic (H1N1) 2009 in Child, Israel”. The child was subsequently treated with oseltamivir, but the sample collected prior to the start of treatment was H274Y positive. Since the brother was the likely index case in the familial cluster, and had not been treated, he likely also had been infected with pH1N1 containing H274Y.

via Community Transmission of pH1N1 Tamiflu Resistance In Israel.

The study conducted by investigators at the Fred Hutchinson Cancer Research Center in Seattle, Washington, and Seattle Children's Hospital, was a randomized, open-label study of TCAD therapy (amantadine and ribavirin administered with oseltamivir) versus oseltamivir monotherapy in immunocompromised patients with Influenza A. The objective of the study was to assess the safety, tolerability, and virologic benefit of oral TCAD therapy. A total of seven patients with confirmed influenza A were enrolled. Data from the study demonstrated that up to 10 days of TCAD therapy was observed to be well tolerated, with five of six TCAD-treated subjects who completed the study achieving a clinical response by day 10. In contrast, the single patient in the oseltamivir monotherapy treatment arm did not respond to 20 days of treatment. Importantly, this patient developed an oseltamivir resistant strain by day seven that persisted to the end of treatment, resulting in the shedding of a multidrug resistant (MDR) strain of influenza.

via Adamas Pharmaceuticals’ Triple Combination Antiviral Drug (TCAD) Therapy is Well Tolerated in a Pilot Study… — EMERYVILLE, Calif., April 28 /PRNewswire/ –.

The CDC in South Korea has released 16 pH1N1 NA sequences at Genbank and 10 had H274Y. Although multiple samples appear to have been collected from two patients, more than half of the patients had H274Y, including the two infected in 2010. This increase of H274Y in recent cases is similar to data released by NIID in Japan. They recently released two more sequences, including one from 2010 and both had H274Y. Earlier, they had released recent sequences including seven from 2010 and six had H274Y. Thus, there have now been 10 sequences from Japan or Korea patients infected in 2010, and nine had H274Y, providing strong evidence of H274Y fixing on pH1N1.

via Widespread pH1N1 Tamiflu Resistance In South Korea.

Quick treatment with flu medicine saved the lives of many pregnant women who were stricken by swine flu last year, according to the most complete analysis of deaths among expectant mothers.

The study by the Centers for Disease Control and Prevention counted 56 pregnant women who died from the new virus in 2009, confirming the dangers of the disease to this group.

Based primarily on U.S. figures from the first few months of the global epidemic, which began last April, CDC officials believe that though pregnant women account for just 1 percent of the population, they have at times accounted for as many as 5 percent of swine flu deaths.

The analysis found that only one of the U.S. women who died was treated with flu medicine like Tamiflu within the first two days of symptoms; just four of those who died got treatment within the first four days.

“Early treatment really makes a difference,” said Dr. Sonja Rasmussen of the CDC, one of the study's authors.

via The Associated Press: Flu drugs saved many pregnant swine flu victims.

Monotherapy with oseltamivir shows greater efficacy than its combination with zanamivir, and than zanamivir alone, in patients with seasonal influenza, according to a study presented here at the 20th European Congress of Clinical Microbiology and Infectious Diseases ECCMID.

via News – Oseltamivir Monotherapy Remains the Best First-Line Antiviral Strategy for Influenza: Presented at ECCMID.