CDC Briefs Media on Swine Influenza

The CDC Briefing on Public Health Investigation of Human Cases of Swine Influenza was held today at 1 pm Eastern time. CDC is working closely with health officials in California, Texas, Mexico, Canada and the World Health Organization.
At this time there are a total of 15 confirmed cases of swine flu in North America.

Background information

The swine flu does not normally infect humans. There is the one case in Wisconsin in 1988 resulted in multiple human infections, and, although no community outbreak resulted, there was antibody evidence of virus transmission from the patient to health care workers who had close contact with the patient.

Between December 2005 through February 2009 there were a total of 12 cases of human infection with swine influenza.

According to the CDC it takes time to have a true diagnosis of swine flu. To diagnose swine influenza A infection, a respiratory specimen would generally need to be collected within the first 4 to 5 days of illness (when an infected person is most likely to be shedding virus). However, some persons, especially children, may shed virus for 10 days or longer. Identification as a swine flu influenza A virus requires sending the specimen to CDC for laboratory testing.

A new vaccine is being worked on because the normal vaccines do not deal with the swine flu strains. The H1N1 swine flu viruses are antigenically very different from human H1N1 viruses and, therefore, vaccines for human seasonal flu would not provide protection from H1N1 swine flu viruses. Making a vaccine is quite complex. It takes months to make a new vaccine.

Schuchat says, “A new vaccine will not happen tomorrow.”

People with swine influenza virus infection should be considered potentially contagious as long as they are symptomatic and possible for up to 7 days following illness onset. Children, especially younger children, might potentially be contagious for longer periods.

All unsubtypable influenza A specimens at this time in the United States are being sent to the Viral Surveillance and Diagnostic Branch of the CDC’s Influenza Division for further diagnostic testing.

The Conference

Glen Nowak, media relations of the CDC introduced Anne Schuchat, M.D, Interim Deputy Director for Science and Public Health Program and Daniel Jernigan, M.D. Ph D. Medical Epidemiology, Influenza Division to the press. Dr. Schuchat took most of the questions and gave a brief update at the start of the conference.

“Starting with the general view. We are worried and acting aggressively. There is not a lot of new information about this illness. There are 8 confirmed cases in the United States.

Mexico is in a serious situation with severe disease and numbers of infection.

“At this time it is hard to predict the next step. We are very committed at the CDC with getting information out and shared as quickly as we can.”

The investigations in the United States are ongoing. State labs and the CDC are looking at a number of suspicious cases. At this time Mexico, Canada and the public health teams in Southern California and Texas as well as the CDC are working together.

The CDC has put up a new web page to deal with this situation.

“This is a time of uncertainty,” says Schuchat. “At this time the cases in the United States have been mild. That is not true in Mexico. We are taking action early.”

The CDC is not confirming where other investigations are ongoing saying that local public health departments are working on a case by case basis. Public health labs are trained in spotting new strains of influenza. When a new strain or untyped strain is found then it is sent to the CDC labs for more advanced testing.

Homeland Security has been informed and is working closely with the CDC on details that could take place.

While WHO has yet to upgrade the phase of this outbreak it is important to know that it does not change the direction that the CDC is heading. Public health departments are acting quite aggressively on this situation.

Schuchat stressed that it is always challenging to get the message out to the public. The CDC is worried. This is a very serious condition in the United States. Involved leaderships are aware of the severe situation and are dealing with it on a day to day manner. The trouble with the general flu is that it spreads easily. The CDC is looking into how easily this strain of the flu is spreading.

At this time the CDC is looking for clusters of severe disease in the United States. This can be problematic as the flu mimics many other illnesses. Because of this it can take time to put the pieces of the puzzle together.

It is not known why the Mexican cases have been more severe than the reported US cases. They may be co-factors in this. It may also be that Mexico has yet to tag less severe cases and the United States has yet to tag more severe cases.

The one thing to remember about the flu is that is does not act in a normal manner. Researchers can make predictions about what could happen and the flu virus may not act in the way that was predicted.

There are quite a number of cases being investigated in the United States at this time. The CDC is not able to give actual numbers nor locations of where those investigations are. The process of testing is rather complex. The first stage is at the hospital where a rapid test can tell if a person has the flu. The sample is then sent to the public health lab for more complex testing. It only is sent to the CDC if the strain is untypeable or in this case the new virus. For that reason the clear number of specimens being tested throughout the US is not known.

“What we know right now is that we can not contain the spread of this Swine flu,” says Schuchat. “We are not at a point to keep the virus in one place. It is likely that we will find it in more places.”

Two confirmed cases were investigated from the border patrol system. There are ongoing respiratory flu testing going on at the border of the United States and Mexico.

Mexico is just in the beginning stages of broad national surveillance.

In the United States a lot of work is happening within local public health departments. Bigger cities are rapidly preparing for the worse case scenario.

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