Domestic travel can cause a virus to become entrenched in a community

Flickr/Dr. Jaus

Antivirals like oseltamivir and zanamivir, the only drugs known to work against swine flu — influenza A(H1N1) — are only modestly effective against the symptoms of flu.

A study by Australian, Italian and US scientists published by the British Medical Journal last week (8 December) also found no clear evidence that taking the drugs can prevent serious complications from flu.

The research, which analysed data from 20 trials, was an update of a 2005 UK Cochrane Review on the effectiveness of the drug class that includes oseltamivir and zanamivir.

Reuters reported the same day that pharmaceutical company, Roche, which manufacturers the oseltamivir drug, Tamiflu, contested the findings.

One in 2000 people who caught A(H1N1) in two US cities has died from the virus, researchers concluded in an article published in PLoS Medicine. This makes A(H1N1)'s death rate similar to seasonal flu.

Reuters reported last week (7 December) that scientists might find the figures "reassuring" but that they do not guarantee the virus would not get worse.

Children with the inherited blood disorder, sickle cell anaemia — common in Sub-Saharan Africa — are more likely to develop complications from influenza A(H1N1), researchers have found.

A study by the US-based Johns Hopkins Children's Center, presented to the American Society of Haematology last week (7 December), found that children with sickle cell anaemia were three times more likely to develop complications from A(H1N1) than their healthy counterparts.

Influenza A(H1N1) is circulating in Africa but is being overlooked because of poor surveillance, according to researchers writing in PLoS Medicine today (14 December). Flu spreads all year round in the tropics and surveillance is improving in Latin America and South-East Asia but little is known about flu and the effectiveness of flu vaccines in Africa, they said.

US scientists have used data about how and why people travel to create a computer model that simulates the spread of a flu-like virus starting with an outbreak in Hanoi, Vietnam.

The researchers collected information from 29 countries on five continents. They reported in the Proceedings of the National Academy of Science (PNAS) today (14 December) that although it is well-known that international air travel spreads disease, domestic travel can cause a virus to become entrenched in a community.

Influenza A(H1N1) used a new mutation to leap from birds to humans [911kB], researchers reported last week (8 December) in PNAS. Previous pandemic viruses shared a genetic mutation that allowed them to replicate in human cells but A(H1N1) has a different mutation that appears to stop human cells from suppressing the virus.

"This is an extremely rare mutation and a rare combination, which suggests that there may be other ways that haven't emerged yet that these viruses are going to evolve," said researcher Jennifer Doudna.

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