12 November 2009
H1N1 Flu Activity Rising in Several Northern Hemisphere Countries
Cross-species H1N1 transmission reported in some swine herds, turkeys, pets
Washington — Pandemic H1N1 influenza virus has become the dominant flu virus in all countries and territories where people are affected, according to the World Health Organization (WHO), and the illness that H1N1 produces has specific features that differentiate it from seasonal flu.
As of November 1, more than 199 countries and overseas territories/communities have reported 482,300 laboratory-confirmed cases of pandemic influenza H1N1 2009, including 6,071 deaths. The case count is much lower than actual cases because many countries have stopped counting individual cases, particularly of milder illness.
Intense and persistent flu transmission continues to be reported in North America and there is no evidence of a peak in activity.
“Flu activity has leveled off in the Southern Hemisphere, although there may be pockets of activity in some countries,” Dr. Keji Fukuda, special adviser to the WHO director-general on pandemic influenza, said at a November 5 briefing.
“But in the Northern Hemisphere we clearly are seeing that infections are picking up in a number of different countries,” he said. “What this means is that we anticipate seeing continued or increased activity during the winter period in the Northern Hemisphere. This also means that we expect to see continued reports of serious cases coming out of countries, and deaths.”
In Europe and Central and Western Asia, pandemic flu activity continues to increase across many countries, signaling an unusually early start to the winter flu season. There is evidence of increasing H1N1 transmission in Northern and Eastern Europe (including Ukraine and Belarus) and eastern Russia.
In Western Asia and the Eastern Mediterranean region, increasing activity has been reported in Oman and Afghanistan.
SEASONAL AND PANDEMIC FLU
Flu epidemics occur every year during autumn and winter in temperate regions. Illnesses cause hospitalizations and deaths mainly among high-risk groups: the very young, elderly and chronically ill. Worldwide, these annual epidemics result in 3 million to 5 million cases of severe illness and 250,000 to 500,000 deaths. Most deaths associated with flu in industrialized countries occur among people age 65 or older. In some tropical countries, flu viruses circulate throughout the year with one or two peaks during rainy seasons.
H1N1 is about as transmissible and infectious as seasonal flu. Most people who get infected develop a self-limiting illness and get better without any special interventions. Also like seasonal flu, H1N1 activity is higher in winter. But H1N1 is different from seasonal flu in that there were high levels of H1N1 in some countries during summer months. Serious illnesses and deaths from H1N1 are concentrated in people younger than 65. In some countries H1N1 infection has been mild; other countries have experienced more severe disease.
When people get infected with H1N1, symptoms include fever, body aches, coughs and sore throats. Complications occur in people who have underlying health conditions and in pregnant women, but they also occur in people who are young and healthy.
H1N1 HIGHLIGHTS
Following are highlights of pandemic H1N1 characteristics, and where to go for the best sources of information:
• Because flu viruses mutate easily, WHO expects to see the H1N1 viruses begin to change over time. But for now, the viruses remain stable and vulnerable to vaccines and anti-virals.
• Vaccine programs have begun in more than 20 countries. Side effects such as soreness, redness and swelling in the arm after an injection are similar to what is seen with seasonal flu shots. There is no evidence of unusual or unexpected side effects.
• Based on pledges by 11 countries and four vaccine manufacturers, WHO is expecting to receive 200 million doses of H1N1 vaccine for the 95 countries that otherwise would not be able to afford it. The vaccine has not yet arrived but WHO is working with donor countries to get the vaccine to recipient countries.
• The WHO Strategic Advisory Group of Experts on Immunization recommended that one dose of vaccine will be adequate for people 10 years old and older. For children 6 months to 9 years old, two doses are recommended, but only one dose should be used if vaccine quantities are limited so more children can be vaccinated.
• Since the new H1N1 pandemic virus emerged, a small number of infections in swine herds has been reported. Limited evidence suggests that these infections occurred after direct transmission of the virus from infected people to swine. Pandemic infections have been reported in turkeys in Chile and Canada and in a few pet animals in the United States. These infections were isolated events and pose no special risks to human health.
• According to WHO, these findings suggest that flu viruses in animals and people increasingly behave like a pool of genes circulating among multiple hosts and that the potential exists for novel flu viruses to be generated in animals other than swine. The situation reinforces the need for close monitoring and collaboration among public health and veterinary authorities.
H1N1 RESOURCES
For the most accurate information about the H1N1 pandemic, visit the following Web sites:
Centers for Disease Control and Prevention
