FACTS ABOUT THE NEW SWINE FLU EPIDEMIC

Is Mexico city ground zero for a global epidemic of a new kind of flu — a strange mix of human, pig and bird viruses?

The illnesses breaking out in Mexico currently have epidemiologists at the U.S. Centers for Disease Control and Prevention deeply concerned. The World Health Organization [W.H.O.] says there have been 800 cases in Mexico in recent weeks, 60 of them fatal, of a flulike illness that appeared to be more serious than the regular seasonal flu. Doctors have warned for years about the potential for a pandemic from viruses that mix genetic material from humans and animals. The most notorious flu pandemic, thought to have killed at least 40 million people worldwide in 1918-19, also first struck otherwise healthy young adults. Scientists have long been concerned that a new killer flu could evolve when different viruses infect a pig, a person or a bird, mingling their genetic material. The resulting hybrid could spread quickly because people would have no natural defenses against it.

Most of Mexico’s dead are young, healthy adults, and none were over 60 or under 3 years old, the World Health Organization said. That alarms health officials because seasonal flus cause most of their deaths among infants and bedridden elderly people, but pandemic flus — like the 1918 Spanish flu, and the 1957 and 1968 pandemics — often strike young, healthy people the hardest. The leading theory on why so many young, healthy people die in pandemics is the “cytokine storm,” in which vigorous immune systems pour out antibodies to attack the new virus. That can inflame lung cells until they leak fluid, which can overwhelm the lungs. But older people who have had the flu repeatedly in their lives may have some antibodies that provide cross-protection to the new strain, she said. And immune responses among the aged are not as vigorous.

FACTS:
• Swine Influenza (swine flu) is a respiratory disease of pigs caused by type A influenza that regularly cause outbreaks of influenza among pigs.

• Swine flu viruses do not normally infect humans, however, human infections with swine flu do occur, and cases of human-to-human spread of swine flu viruses has been documented.

• From December 2005 through February 2009, a total of 12 human infections with swine influenza were reported from 10 states in the United States.

• Since March 2009, a number of confirmed human cases of a new strain of swine influenza A (H1N1) virus infection in California, Texas, and Mexico have been identified. An investigation into these cases is ongoing.

• The C.D.C. said that eight nonfatal cases had been confirmed in the United States, and that it had sent teams to California and Texas to investigate.

• Still, only a small number have been confirmed as cases of the new H1N1 swine flu, according to , a W.H.O. spokesman.

• Tests show 20 people in Mexico have died of the new swine flu strain, and that 48 other deaths were probably due to the same strain.

• The caseload of those sickened has grown to 1,004 in Mexico.

• The same virus also sickened at least eight people in Texas and California, though there have been no deaths yet in the U.S.

• If the confirmed deaths are the first signs of a pandemic, then cases are probably incubating around the world by now, says a pandemic flu expert.

• The new strain contains gene sequences from North American and Eurasian swine flus, North American bird flu and North American human flu, said the Centers for Disease Control and Prevention.

• This similar virus has been found in the American Southwest, where officials have reported eight nonfatal cases.

This swine flu and regular flu can have similar symptoms — mostly fever, cough and sore throat, though some of the U.S. victims who recovered also experienced vomiting and diarrhea.

UP-TO-DATE ACTIONS ON SWINE FLU
The World Health Organization has convened an emergency expert panel to consider whether to declare the outbreak an international public health emergency — a step that could lead to travel advisories, trade restrictions and border closures.

• The CDC and Canadian health officials were studying samples sent from Mexico, and some governments around Latin America said they would monitor passengers arriving on flights from Mexico.

• No vaccine specifically protects against swine flu, and it is unclear how much protection current human flu vaccines might offer.

• Actually producing the vaccines could take months.

• The relatively good news is--CDC says two flu drugs, Tamiflu and Relenza, seem effective against the new strain. Roche, the maker of Tamiflu, said the company is prepared to immediately deploy a stockpile of the drug if requested. Both drugs must be taken early, within a few days of the onset of symptoms, to be most effective.

• anyone with a fever, a cough, a sore throat, shortness of breath or muscle and joint pain should seek medical attention.

• When a new virus emerges, it can sweep through the population.

• The Spanish flu is believed to have infected at least 25 percent of the United States population, but killed less than 3 percent of those infected.

• Among the swine flu cases in the United States, none had had any contact with pigs; cases involving a father and daughter and two 16-year-old schoolmates convinced the authorities that the virus was being transmitted from person to person.

LINKS TO MORE FACTS
General Information about Swine Flu

Questions and answers and guidance for treatment and infection control
Human Swine Flu Investigation Apr 24, 2009
Information about the investigation of human swine flu in California

Swine Influenza: General Information

Swine Flu and You Apr 24, 2009
What is swine flu? Are there human infections with swine flu in the U.S.?

Swine Flu Video Podcast Apr 25, 2009
Dr. Joe Bresee, with the CDC Influenza Division, describes swine flu - its signs and symptoms, how it's transmitted, medicines to treat it, steps people can take to protect themselves from it, and what people should do if they become ill.

Key Facts about Swine Influenza (Swine Flu) Apr 24, 2009, 5:45 PM ET
How does swine flu spread? Can people catch swine flu from eating pork?