Influenza; Strep throat; Bird flu; Avian influenza
Colds rarely cause serious complications. In about 1% of cases, a cold can lead to other complications, such as sinus or ear infections. It can also aggravate asthma and, in uncommon situations, increase the risk for lower respiratory tract infections.
Ear Infections. The rhinovirus infection, a major cause of colds, also commonly predisposes children to ear infections, possibly by obstructing the Eustachian tube, which leads to the middle ear. Viruses may even attack the ear directly.
Sinusitis. Between 0.5 - 3% of people with colds develop sinusitis, an infection in the sinus cavities (air-filled spaces in the skull). Sinusitis is usually mild, but if it becomes severe, antibiotics generally eliminate further problems. In rare cases, however, sinusitis can be serious.
Lower Respiratory Tract Infections. The common cold poses a risk for bronchitis and pneumonia in nursing home patients, and in other people who may be vulnerable to infection. Some experts believe that the rhinovirus may play a more significant role than the flu in causing lower respiratory infections in the vulnerable population.
Aggravation of Asthma. Rhinovirus infections can aggravate asthma in both children and adults. In fact, rhinovirus has been reported to be the most common infectious organism associated with asthma attacks. Colds may promote allergic inflammation of the airways, and increase the intensity of their responsiveness for weeks.
The flu is usually self-limited. However, each year in the United States, more than 200,000 people are hospitalized due to complications of the flu. An estimated 36,000 people die each year of influenza-related complications. People at highest risk for serious complications are those over 65 years old and those with chronic medical conditions. Influenza A is the most severe strain. Influenza B tends to be milder.
Pneumonia. Pneumonia is the major serious complication of influenza and can be very serious. It can develop about 5 days after viral influenza. More than 90% of the deaths caused by influenza and pneumonia occur among older adults. Flu-related pneumonia nearly always occurs in high-risk individuals, such as the following:
Combinations of these factors further increase the risk. It should be noted that pneumonia is an uncommon outcome of influenza in healthy adults.
Complications in the Central Nervous System in Children. Influenza increases the risk for complications in the central nervous system of small children. Febrile seizures are the most common neurologic complication in children The risks decline after a child turns 1 year old, but are still high in children aged 3 - 5 years old.
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