Swine Flu: a Quick Overview
Posted on April 26, 2009 Comments (8)
World Health Organization on Swine influenza
After reviewing available data on the current situation, Committee members identified a number of gaps in knowledge about the clinical features, epidemiology, and virology of reported cases and the appropriate responses. The Committee advised that answers to several specific questions were needed to facilitate its work.
The Committee nevertheless agreed that the current situation constitutes a public health emergency of international concern.
Based on this advice, the Director-General has determined that the current events constitute a public health emergency of international concern, under the Regulations.
Swine flu: a quick overview–and new New York and Kansas cases by Tara Smith
while the cases in the US have been mild and no deaths have occurred that we’re aware of, it seems in Mexico that young people are dying from this–a group that is typically not hard-hit by seasonal influenza viruses. Readers familiar with influenza and know the history of the 1918 influenza pandemic will recall that the “young and healthy” were disproportionally struck by that virus as well–so this knowledge is currently disconcerting and worrisome, but there are so many gaps in our information as far as what’s really going on in Mexico that it’s difficult to make heads or tails out of this data right now.
Third, is this really a new virus? So few influenza isolates are actually analyzed each year (in proportion to the number of people infected) that we aren’t sure yet whether this is something brand-new, or something that has been circulating at a low level for awhile, but just hadn’t been picked up. After all, H1N1 is a common serotype, so additional molecular testing is needed to determine that it’s “swine flu” versus “human” H1N1.
this is a fast-developing story, and it will take much more investigation and field work to determine the true extent of the virus’s spread in the population; to figure out… how efficiently it’s transmitted…
This is very early in the scientific inquiry process looking into what exactly is going on. It is too early to tell how serious a threat this is. The reaction of WHO, CDC though shows they are taking the threat seriously. By far the biggest danger in such situations, is reacting too slowly to serious and contagious threats. If you wait to react until proof exists that the situation is very serious the situation can be almost impossible to control. So you need to react quickly to shut down the spread of the threat, hopefully before it has spread too far.
Related: CDC site on Human Swine Influenza Investigation – Interview with Dr. Tara Smith – Reducing the Impact of a Flu Pandemic – H5N1 Influenza Evolution and Spread
The evolving Swine Flu story
It turns out this virus is highly unusual, a quadruple reassortant. The genes of a flu virus are packaged in eight discrete segments. When two flu viruses infect the same host cell, the segments of each are copied and repackaged, 8 at a time, in new viral particles which then bud off from the infected cell. They then may infect a new host cell. In this repackaging process the segments of the two different viruses may mix and match, so that new virus particle will have segments from two different viruses. The new virus is, in a sense, not just a swine flu virus. It does have viral segments characteristic of two different families of swine flu, one typical of North America, where swine flu is endemic, and one typical of pig flu viruses from Europe and Asia. But we learned today that it also has viral segments seen in North American birds and in human seasonal influenza.
Mexico flu sparks worldwide fear
Ten New Zealand students are among a group which travelled to Mexico have tested positive for influenza A – making it “likely”, though not definite, that they are infected with swine flu, said Health Minister Tony Ryall
Schools in and around Mexico City have been closed until 6 May, and some 70% of bars and restaurants in the capital have been temporarily closed
Mexico’s Health Secretary, Jose Cordova, said a total of 1,324 people had been admitted to hospital with suspected symptoms since 13 April and were being tested for the virus. “In that same period, 81 deaths were recorded probably linked to the virus but only in 20 cases we have the laboratory tests to confirm it,” he said.
Mexico’s President Felipe Calderon has announced emergency measures to deal with the situation. They include powers to isolate individuals suspected of having the virus without fear of legal repercussions.
Mexican Swine Flu Death Toll Growing, 81 Died
Officials in Mexico suspect more than 1,300 Mexicans have been sickened by the virus. Sunday Mass has been suspended in many Roman Catholic churches throughout the country.
Mexico City’s mayor has canceled all public events for 10 days, and the country’s health department has been given the power to isolate patients and inspect travelers.