Swine Flu

Swine influenza virus (SIV) is caused by Orthomyxoviruses that are endemic to pig populations. SIV strains isolated to date have been classified either as Influenzavirus C or one of the various subtypes of the genus Influenzavirus A.

Swine flu, unlike bird flu, is able to pass from human to human contact. The 2009 swine flu outbreak is the spread of a new strain of H1N1 influenza virus that was first detected by public health agencies in March 2009. Local outbreaks of influenza-like illness were detected in three areas of Mexico, but the presence of this new strain was not discovered for a month.

Following this discovery in the parts of United States bordering Mexico, its presence was swiftly confirmed in the local outbreaks in Mexico, and in isolated cases elsewhere. By April 27, the new strain was confirmed also in Canada, Spain, and the United Kingdom and suspected in many other nations, with over 1,800 candidate cases.

The new strain is an apparent reassortment of several strains of influenza A virus subtype H1N1, including a strain endemic in humans and two strains endemic in pigs, as well as an avian influenza.

Reassortment is common in influenza viruses, due to the structure of their genome. This particular reassortment is consistent with a transmission of swine influenza from pig to human combined with the mixing of two viral infections in the same person.

In April both the World Health Organization (WHO) and the United States Centers for Disease Control and Prevention (CDC) expressed serious concerns about this novel strain, because it apparently transmits from human to human, has had a relatively high mortality rate in Mexico, and because it has the potential to become a flu pandemic.

On April 25, 2009, the WHO determined the situation to be a formal “public health emergency of international concern”, with knowledge lacking in regard to “the clinical features, epidemiology, and virology of reported cases and the appropriate responses”.

Government health agencies around the world also expressed concerns over the outbreak and are monitoring the situation closely.

Recommendations to prevent infection by the virus consist of the standard personal precautions against influenza. This includes frequent washing of hands with soap and water or with alcohol-based hand sanitizers, especially after being out in public. People should avoid touching their mouth, nose or eyes with their hands unless they've washed their hands. If people do cough, they should either cough into a tissue and throw it in the garbage immediately or, if they cough in their hand, they should wash their hands immediately.

Many countries confirmed that inbound international passengers will be screened. Typical airport health screening involves asking passengers which countries they have visited and checking whether they feel or look particularly unwell.

On April 27, the CDC recommended the use of Tamiflu and Relenza for both treatment and prevention of the new strain.

Some physicians in the US are recommending the use of masks when in public. The purpose of a face mask is to effectively cover a person’s mouth and nose so that if a person is around someone who is infected, there is a decreased likelihood of transmission.

Cases by country
Country	Laboratory confirmed cases	Other possible cases*	Attributed deaths‡	Refs.
Mexico (details)	26	1,995	149 (20)	[1][2]
United States (details)	48	212+	0	[3][2][4]
Canada (details)	6	28+	0	[2][5]
United Kingdom (details)	2	21	0	[6]
Spain (details)	1	35	0	[7][8]
New Zealand	0	56	0	[9]
Australia	0	19	0	[10][11]
Colombia	0	12	0	[12]
Brazil	0	11	0	[13][14]
Switzerland	0	5	0	[15]
Denmark	0	4	0	[16]
Ireland	0	4	0	[17]
Czech Republic	0	3	0	[18]
Poland	0	3	0	[19]
France	0	3	0	[20]
Guatemala	0	3	0	[21]
Israel	0	2	0	[22]
Argentina	0	1	0	[23]
Costa Rica	0	1	0	[24]
Peru	0	1	0	[25]
Russia	0	1	0	[26]
South Korea	0	1	0	[27]
Totals	83	2,443+	149 (20)
* Not all cases have been confirmed as being due to this strain. Possible cases are cases of influenza-like illness (ILI) that have not been confirmed through testing to be due to this strain. ‡ Deaths with confirmed presence of virus in parentheses.

Questions and answers about swine flu

Mexico is contending with an outbreak of swine flu, suspected in the deaths of dozens of people and sickening perhaps 1,000. In the United States, at least eight cases have been confirmed with the infection, all of them in California and Texas; only one person was hospitalized. Here are some questions and answers about the illness:


Q. What is swine flu?

A. Swine flu is a respiratory illness in pigs caused by a virus. The swine flu virus routinely causes outbreaks in pigs but doesn’t usually kill many of them.

Q. Can people get swine flu?

A. Swine flu viruses don’t usually infect humans. There have been occasional cases, usually among people who’ve had direct contact with infected pigs, such as farm workers. “We’ve seen swine influenza in humans over the past several years, and in most cases, it’s come from direct pig contact. This seems to be different,” said Dr. Arnold Monto, a flu expert with the University of Michigan.

Q. Can it spread among humans?

A. There have been cases of the virus spreading from human to human, probably in the same way as seasonal flu, through coughing and sneezing by infected people.

Q. What are the symptoms of swine flu?

A. The symptoms are similar to those of regular flu — fever, cough, fatigue, lack of appetite.

Q. Is the same swine flu virus making people sick in Mexico and the U.S.?

A. The Centers for Disease Control and Prevention said the Mexican virus samples match the U.S. virus. The virus is a mix of human virus, bird virus from North America and pig viruses from North America, Europe and Asia.

Q. Are there drugs to treat swine flu in humans?

A. There are four different drugs approved in the U.S. to treat the flu, but the new virus has shown resistance to the two oldest. If you suspects any symptoms of Swine flu, contact your physician.

Q. Does a regular flu shot protect against swine flu?

A. The seasonal flu vaccine used in the U.S. this year won’t likely provide protection against the latest swine flu virus. There is a swine flu vaccine for pigs but not for humans.

Q. Should residents of California or Texas do anything special?

A. The CDC recommends routine precautions to prevent the spread of infectious diseases: wash your hands often, cover your nose and mouth when you cough or sneeze, avoid close contact with sick people. If you are sick, stay at home and limit contact with others.

Q. What about traveling to Mexico?

A. The CDC has not warned Americans against traveling to Mexico but advises that they be aware of the illnesses there and take precautions to protect against infections, like washing their hands.

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Swine Flu Symptoms

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Too Little Vitamin D May Mean More Colds and Flu

By Alan Mozes, HealthDay

- Forget the apple. The largest study of its kind to date shows that vitamin D each and every day is what will keep the doctor away when it comes to the common cold or the flu.

The finding is based on an assessment of vitamin D levels, nutritional habits and respiratory infection rates among nearly 19,000 American men and women.

"We don't want to jump ahead of ourselves," said study author Dr. Adit Ginde, an assistant professor of surgery in the division of emergency medicine at the University of Colorado Denver School of Medicine. "But our study provides support that lower levels of vitamin D are associated with an increased risk for respiratory infections, such as the common cold and the flu. And people who have pre-existing respiratory disease -- like asthma an emphysema -- appear to be at an increased risk for this association."

Ginde's team, from Harvard Medical School and Children's Hospital Boston, reports its findings in the Feb. 23 issue of the Archives of Internal Medicine.

Vitamin D can be found in such foods as canned tuna, cereal and fortified milk or juice, according to the American Dietetic Association (ADA). The body can also be triggered to naturally produce vitamin D after adequate exposure to sunlight.

In addition to its well-established role as a calcium builder and bone fortifier, vitamin D has recently been touted as having a protective role against both colon cancer and multiple sclerosis, the ADA noted.

And in December, a review of studies conducted by researchers at the Mid-America Heart Institute in Kansas City suggested that those with vitamin D deficiency -- a designation estimated to include about half of American adults and nearly one in three children -- might face an increased risk for heart attack and stroke.

To gauge the specific relationship between vitamin D and respiratory risk, Ginde's team analyzed data from the Third National Health and Nutrition Examination Survey, collected from 1988 to 1994.

Participants were aged 12 and up -- with an average age of 38 -- and three-quarters were white. All completed nutritional and health surveys and had physical examinations. Blood samples were taken to measure levels of 25-hydroxyvitamin D, considered to be the optimal measure of vitamin D status.

The researchers found that those with less than 10 nanograms of vitamin D per milliliter of blood, considered low, were nearly 40 percent more likely to have had a respiratory infection than those with vitamin D levels of 30 ng or higher. The finding was consistent across all races and ages.

In particular, people who had a history of asthma or some form of chronic obstructive pulmonary disease (COPD) were even more likely to suffer from vitamin D deficiencies.

Asthma patients with the lowest vitamin D levels had five times the risk for respiratory infection, and vitamin D-deficient COPD patients had twice the risk.

"We still need to do the clinical trials that we already have planned to definitely say whether supplementation with vitamin D would actually reduce the risk we found," Ginde cautioned. "But I think we can say that most Americans probably do need more vitamin D for its effects on bone health, as well as for its general benefits with respect to the immune system."

Lona Sandon, an assistant professor of clinical nutrition at the University of Texas Southwestern Medical Center and a spokeswoman for the American Dietetic Association, said that evidence of a vitamin D-immune system connection seems "pretty strong."

"There does seem to be a link because, when we're not getting enough vitamin D, our immune system appears not to function at its best," she said.

Sandon noted, however, that getting enough vitamin D from food alone can be difficult.

"The best sources are salmon with the bones, or three cups a day of milk," she said. "But not many people get that. So I would say, get outside and expose some skin to the sun. Dermatologists don't always like that advice because they're concerned with skin cancer, but just 15 minutes a day at the sun's peak -- roughly 11 to 1 -- does the trick."

"However," Sandon added, "if you live north of Atlanta, in the middle of winter it's hard to get enough vitamin D that way, even if you're out in the middle of the day. So that leaves us with supplements in some form. And in that case, a general multivitamin typically has about 200 Ius [international units] of vitamin D, which is considered adequate."

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