Influenza; Strep throat; Bird flu; Avian influenza
Vaccines are available to prevent influenza (See Viral Influenza Vaccines section in this report).
For mild influenza, symptom relief is similar to that for colds.
Two classes of antiviral agents have been developed to treat influenza: neuraminidase inhibitors and M2 inhibitors. These drugs can shorten symptoms but there is no indication that they can prevent or reduce infections. They do not help if they are started after the first 36 hours of illness. Because of emerging drug resistance, some experts suggest these drugs be reserved for severely ill patients or those at high risk.
Brands and Benefits. Zanamivir (Relenza) and oseltamivir (Tamiflu) are neuraminidase inhibitors. They are newer agents that have been designed to block a key viral enzyme, neuraminidase, which is involved with viral replication. While effective, their overall benefit is modest.
Important points about the use of these drugs:
Limitations and Side Effects. Although they have many advantages compared to the M2 inhibitors, neuraminidase inhibitors are much more expensive. They also need to be taken within 2 days of the start of symptoms to be effective. Neither neuraminidase inhibitor is effective against influenza-like illness (one that is not caused by an influenza virus). There are also some differences between the two drugs that could be significant for some individuals:
The current use of neuraminidase inhibitors in different age and patient groups is as follows:
Brands and Benefits. Amantadine (Symmetrel) and rimantadine (Flumadine) are M2 inhibitors. The following benefits may apply to the minority of strains of influenza A that remain sensitive to the drugs:
Limitations. Drawbacks of M2 inhibitors include:
Side Effects. Both M2 inhibitors occasionally cause nausea, vomiting, indigestion, insomnia, and hallucinations. Amantadine affects the nervous system and about 10% of people experience nervousness, depression, anxiety, difficulty concentrating, and lightheadedness. Rimantadine is less likely to do so. Rarely, amantadine can cause seizures, usually in elderly people already at risk for psychiatric symptoms.
Note: Amantadine is a standard treatment for Parkinson's disease and should be continued for that condition.
"Flu Shots." These vaccines use inactivated (not live) viruses. They are designed to provoke the immune system to attack antigens contained on the surface of the virus. (Antigens are foreign molecules that the immune system specifically recognizes as alien and targets for attack.)
Unfortunately, the antigens in these influenza viruses undergo genetic changes (called antigenic drift) over time, so they are likely to become resistant to a vaccine that worked in the previous year. Vaccines are then redesigned annually to match the current strain.
Intranasal (inside the nose) vaccine. A live but weakened intranasal vaccine (FluMist) is proving to be effective and safe in healthy, non-pregnant people aged 2 - 49 years and has been approved by the FDA. It is known as a live, attenuated, intranasal influenza vaccine (LAIV). The vaccine is engineered to grow only in the cooler temperatures of the nasal passages, not in the warmer lungs and lower airways. It boosts the specific immune factors in the mucous membranes of the nose that fight off the actual viral infections. FluMist is given using a nasal spray.
Timing and Effectiveness of the Vaccine. Ideally, people should be vaccinated every October or November. However, it may take longer for a full supply of the vaccine to reach certain locations. In such cases, the high-risk groups should be served first.
Antibodies to the influenza virus usually develop within 2 weeks of vaccination, and immunity peaks within 4 - 6 weeks, then gradually wanes.
In healthy adults, immunization typically reduces the chance of illness by about 70 - 90%. The current flu vaccines may be slightly less effective in certain patients, such as the elderly and those with certain chronic diseases. Even in people with a weaker response, however, the vaccine is usually protective against serious flu complications, particularly pneumonia. In fact, among the elderly, interesting studies are now suggesting that influenza vaccination may help protect against stroke, adverse heart events, and death from all causes.
Children Who Should Be Vaccinated. The following children over 6 months should be vaccinated against influenza:
Adults Who Should Be Vaccinated. The following, in order of priority, are the population groups who should be vaccinated each year. The first two groups have the highest need for influenza vaccinations and are given top priority:
Other adults who should consider flu shots include:
Negative Effects. Possible negative responses to the vaccines include:
The FDA approved the first vaccine for humans against H5NI influenza virus in April 2007. The vaccine, which is made from a human strain of the virus, could be used in people ages 18 - 64 to prevent the spread of the virus from human to human. The vaccine requires two doses, given about a month apart. It will not be sold commercially, but instead is being purchased by the U.S. government to be stockpiled and distributed to public health officials in the event of an outbreak of avian flu. The vaccine led to the development of antibodies in 45% of those who received the higher dose studied. The most common side effects reported were pain at the injection site, headache, and muscle pain. Research on the vaccine is continuing.
The intense and widespread use of antibiotics is leading to a serious global problem of antibiotic resistance. The inappropriate use of powerful newer antibiotics for conditions such as colds or sore throats poses a particular risk for resistant strains of bacteria. For example, the number of cases of methicillin-resistant Staphylococcus aureus (MRSA) is increasing in people who have no known risk factors. (MRSA causes sometimes-fatal skin infections.) In 2006, rates of Neisseria gonorrhoeae resistance to the fluoroquinolone antibiotics family exceeded 10%. The CDC no longer recommends treating gonorrhea infections with fluoroquinolone first.
When Antibiotics Are Needed for Upper Respiratory Infections.
Antibiotics do not affect viruses and, in healthy individuals, these drugs are almost never necessary or helpful for influenza or colds, even with persistent cough and thick, green mucus. In one disturbing study, antibiotics were prescribed for nearly half of children who went to the doctor for a common cold.
Antibiotics may be required for upper respiratory tract infections only under certain situations, such as the following:
Patients at Highest Risk for Infection with Resistant Bacteria Strains. Some patients are at greater risk for developing an infection resistant to common antibiotics. At this time, the average person is not endangered by this problem. Risk factors include:
Children at higher risk for antibiotic resistance are those who attend day care, who are exposed to cigarette smoke, who were bottle-fed, and who had siblings with recurrent ear infections.
What the Health Care Community Is Doing. Prescribing antibiotics only when necessary is the most important step in restoring bacterial strains that are susceptible to antibiotics. Encouraging studies are reporting that inappropriate antibiotic prescriptions are on the decline. Prescriptions for other common respiratory infections, such as otitis media, sore throat, acute bronchitis, and colds and flus have been decreasing.
What Patients and Parents Can Do. Patients and parents can also help with the following tips:
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