New Haven need not panic over swine flu, but the new, mysterious virus could become more virulent and spread quickly from neighboring New York, health specialists said.
While there is no reason for alarm in Connecticut right now, new person-to-person infections originating in New York City could blossom here shortly, an infectious diseases expert said Monday.
Since the time between infection and the onset of symptoms is two to four days, any potential Connecticut cases should appear within a few days, said Dr. Jeffrey Kahn, specialist in pediatric infections at the Yale Medical School.
“In a short time we’ll know if this is a true epidemic,” he said.
Federal and international agencies were working Monday to characterize the worrisome type A (H1N1) virus, which has caused about 40 confirmed cases in the U.S.
More than 100 people in Mexico have succumbed to the swine flu since it appeared about two weeks ago. Another 1,600 Mexicans are believed to be infected.
One of the major questions facing researchers is why the new H1N1 virus in Mexico is so much more virulent than its genetic equivalent in the U.S., scientists said.
The U.S. Centers for Disease Control and Prevention declared a “health emergency” on Sunday, which practically means that the organization is trying to organize a overall picture of the emerging infection.
Gov. M. Jodi Rell has directed the state Department of Public Health to closely monitor the swine flu outbreak.
“It is essential that we get on top of this situation as swiftly as possible and take all prudent precautions,” she said in a prepared statement Sunday.
Meanwhile, the best ways to avoid infection from flu and other upper respiratory viruses are to wash your hands frequently and avoid symptomatic people, said Dr. Louise Dembry, epidemiologist at Yale-New Haven Hospital. Avoid touching your eyes, nose or mouth, as this could inadvertently insert viruses into their favorite entry points.
If you are ill, cover your mouth when you cough and sneeze into a tissue, she said. Stay home from work to avoid infecting others. Cloth masks are not likely to prevent infection if an infected person coughs in your face. Infection requires close contact.
People tend to be contagious for about one day before symptoms appear.
“People need to be aware of what’s going on, and take the usual precautions,” Dembry said.
The virus apparently originated in birds, which transmitted it to pigs. It then jumped from swine to humans, acquiring novel genetic traits. This year’s influenza vaccine confers no protection against the swine flu.
“Most cases of swine flu are mild. The CDC and World Health Organization are all over this thing,” Dembry said. “It has the potential to become widespread,” and could become more or less virulent, she said.
Kahn, of Yale, said the risk to any individual in Connecticut is small, unless he has recently visited Mexico. Local people who develop flu-like symptoms — high fever, chills, cough, sore throat, aches, and nausea — could have the type A flu virus that circulated all winter, he said.
Differentiating between the “normal” flu and swine flu can only be performed in special laboratories.
“Distinguishing between the two is difficult. That may change dramatically,” Kahn said.
Consequently, hospitals are preparing for an onslaught of flu-like cases and will be treating new cases of flu as if the virus were swine flu, hospital spokespersons said.
The emerging swine flu is genetically unique, with components from pigs, birds and humans, Kahn said. The H1 N1 swine flu is unrelated to the H5N1 avian flu, or SARS, he said.
Influenza is characterized by H, or hemagglutinin, and N, or neuraminidase. Both are surface proteins that protrude from the spherical virus.
The hemagglutinin and neuraminidase proteins attach to the inner lining of the respiratory or intestinal tracts, allowing the virus to break into cells. Three types of hemagglutinin are known to infect humans. Two neuraminidases have an affinity for people.
Both proteins mutate easily and rapidly, which is why new types of vaccine are necessary every year. These changes are known as genetic drift, said Dr. David Lobo, consultant in infectious diseases at Bridgeport Hospital.
A major change, or genetic shift, can cause a pandemic, like the 1918 Spanish flu, which killed millions of people worldwide.
Whether today’s swine flu is a drift or a shift remains to be discovered, he said. If there is a silver lining in the current outbreak, it is that so far, the new swine flu appears to be sensitive to Tamiflu, an anti-flu drug that inhibits the neuraminidase protein, Lobo said.
While some public health officials say that the world is “due” for a 1918 repeat, pandemics do not occur as frequently as biology suggests they should, said Naomi Rogers, assistant professor of medical history at Yale University.
“After 1956 there hasn’t been anything terrible. That has puzzled people,” she said. “This doesn’t seem like 1918,” she said.