HOUSTON Coughing, sneezing, fever they're all signs of the flu, or are they? According to experts at Baylor College of Medicine (www.bcm.edu [1]), not only are there three different strains of influenza virus circulating that can cause the flu, but there are also several other viruses floating around during flu season that could be invading your immune system.

"The predominant virus that appears to be circulating right now is respiratory syncytial virus, or RSV, which is quite commonly spread among infants and young children, but people of any age can get infected with it," said Dr. Gail Demmler Harrison, professor of pediatrics-infectious disease at BCM and Texas Children's Hospital (www.texaschildrens.org [2]).

Infants with this virus can have flu-like symptoms such as a cold, stuffy nose, ear infection and bronchiolitis, which is inflammation of the small airways that causes wheezing and difficulty breathing. This can cause infants to have trouble nursing or taking a bottle, resulting in dehydration, said Demmler Harrison. It can cause serious problems in premature infants or infants who have underlying lung or heart conditions.

RSV in older children and adults can have symptoms including a cold and bronchitis. Physicians can determine if the virus is RSV through rapid tests, cultures or special molecular tests, and the treatment usually involves drinking plenty of fluids, getting rest and taking medications for mucus relief. Antivirals for RSV are only used in special cases.

However, the effects of RSV can be lessened through a vaccine. Parents should seek out the vaccine for high-risk infants.

Other viruses circulating now during this flu season include parainfluenza, adenovirus, rhinovirus and human metapneumovirus. Parainfluenza usually causes respiratory infections and can cause croup, which causes swelling around the vocal cords, difficulty breathing and cough. Adenovirus can mimic many other viruses and can last for days to weeks. Rhinovirus is the common cold and is fairly minor, but can be worse in high-risk children. Human metapneumovirus is similar to RSV.

Currently, rapid tests can determine whether the infection is RSV, the flu or adenovirus, and more specialized tests can be done to determine exactly which virus is causing the infection. When experiencing symptoms of one of these infections, such as a runny nose, congestion and fever, Demmler Harrison suggests staying home to avoid spreading the infection, drinking plenty of fluids and taking over-the-counter decongestants or cough medications.

"Your immune system is smart enough to help you get over these viruses in most instances," said Demmler Harrison.

However, treatment for influenza virus is recommended in individuals who are at high risk for complications based on their age or underlying medical condition. Warning signs that it may be something more than one of these seasonal viruses include a fever that lasts for more than three days, feeling listless or having a severe cough that cannot be controlled. Parents of young children should always touch base with the pediatrician, especially if they have any underlying health issues.

Those who have not sought out the flu vaccine still have time to do so, and it's important for adults and children to be vaccinated, said Demmler Harrison. Practicing good hygiene, such as covering your mouth when you cough and washing your hands frequently, are also good ways to prevent the spread of these viruses.