COMMON COLD

Most “colds” are upper respiratory tract infections caused by one of a host (at least 200) of viruses. It is not true that exposure to a cold climate (“catching a chill”) causes a cold. Symptoms include runny nose, cough, sore throat, headache, muscle aches, fever, fatigue, weakness, and occasional nausea with vomiting and/or diarrhea. Unfortunately, there is no cure for the common cold. The best medicine is rest, increased fluid intake to prevent dehydration and loosen secretions, and acetaminophen or aspirin for fever. To avoid Reye syndrome (postviral encephalopathy and liver failure), do not use aspirin to control fever in a child under age 17.

Keep the victim warm and dry. For persons ages 6 years and older, treat nasal congestion with an oral decongestant and nasal spray (use the latter for 3 days maximum). Be aware that an oral decongestant can make a child hyperactive. For an infant, use saline nose drops (¼ tsp, or 1.3 mL, of table salt in 1 cup, or 237 mL, of water) in a dose of two to three drops in each nostril a few times a day; the child will sneeze, or the drops can drain via gravity or be sucked out with a “baby bulb” syringe.

A person who breathes steam (which has not been proven to improve a common cold) must be careful to avoid burns. There is no scientific evidence to support the use of chest rubs or megavitamins (specifically, vitamin C) in the prevention or amelioration of viral illnesses. Probably the most important factor in rehabilitation is adequate rest.

Do not attempt to “sweat out” a cold with vigorous exercise. Such harmful behavior causes worsened fever, debilitation, and dehydration. It is a method guaranteed to convert a common cold into pneumonia. A person with a cold should see a doctor if he is ill for more than 3 weeks, his temperature elevation becomes extreme (see page 167), he develops a cough productive of yellow-green or darkened phlegm (see pages 48 and 205), or he develops chest pain associated with breathing, shaking chills, a severe earache, or a headache with a stiff neck (see page 174). Since colds are spread by contact, take particular care to wash your hands after contact with an infected person.

The most common complication of a cold in a child is a middle ear infection. If a child with a runny nose and cough begins to pull at his ear(s) or if a fever returns near the end of the course of a cold, consider treating the child for otitis media (see page 175). Pneumonia can also be a complication (see page 48). It should be suspected in a child who appears short of breath (respiratory rate above 30 per minute in a child, or 40 per minute in an infant).

A cold can be differentiated from seasonal allergies on the basis of the following: cold—fever, chills, yellowish or green nasal discharge, sore throat, diarrhea, muscle aches; allergies—clear nasal discharge, repetitive sneezing, watery and itchy eyes.

Someone who has a chronic (lasts longer than 3 weeks) cough not clearly associated with a cold or other viral infection of the respiratory tract, who is coughing up blood, or who has another known problem such as pneumonia or lung cancer should seek the attention of a physician. The most common causes of a chronic cough are cigarette smoking, postnasal drip (often stimulated by seasonal allergies), unsuspected asthma, chronic sinus infection, or acid reflux from the stomach into the esophagus. In addition, those who take a certain category of medicine (angiotensin-converting enzyme [ACE] inhibitors) to treat high blood pressure may develop a cough; this usually disappears a few days after the medicine is discontinued.

A U.S. FOOD AND DRUG ADMINISTRATION ADVISORY PANEL IN 2007 RECOMMENDED THAT THERE IS NO EVIDENCE THAT OVER-THE-COUNTER COLD AND COUGH MEDICINES WORK IN CHILDREN AND THAT THE PRODUCTS SHOULD NOT BE GIVEN TO CHILDREN YOUNGER THAN 6 YEARS OF AGE.

INFLUENZA

The influenza viruses are responsible for seasonal epidemics of the flu, a predominantly respiratory disease. In temperate climates, influenza is a cold weather disease. The illness is recognized by sudden high fever, sore throat, cough, headache, muscle aches, weakness, and occasional (more common in children) nausea with vomiting and/or diarrhea. “Stomach flu” is a misnomer, because it is not caused by influenza virus, but rather, by other viruses and bacteria. Influenza is distinguished from a common cold by its intensity, particularly of the headache and muscle aches. The virus is transmitted from person to person via virus-laden large droplets (greater than 5 microns in diameter) generated when infected persons cough or sneeze.

Elderly or infirm individuals are at greatest risk for becoming severely debilitated or developing complications, such as pneumonia. General therapy is the same as that for a cold: rest, adequate nutrition, increased fluid intake, and medicine for fever. Vaccines are prepared each year that are somewhat effective in the prevention of types A and B influenza (see page 456). Oseltamivir phosphate (Tamiflu) is a drug that is used for treatment of influenza types A and B in adults who have been ill for no more than 2 days. It is given in an adult oral dose of 75 mg twice daily for 5 days. The pediatric dose is based on age and weight. For a child age 1 to 12 years: weight less than 15 kg, 30 mg twice daily for 5 days; 15 to 23 kg, 45 mg twice daily for 5 days; 23 to 40 kg, 60 mg twice daily for 5 days; weight greater than 40 kg or age greater than 12 years, 75 mg twice daily for 5 days. An alternative is zanamivir (Relenza) 10 mg inhaled twice a day for 5 days for all ages.

During an epidemic, victims may benefit from the administration of the oral drug rimantadine 200 mg by mouth daily for 5 to 7 days in adults, and 5 mg/kg of body weight per day (up to 150 mg) for 5 to 7 days in children. An alternative is amantadine in a dose of 100 mg twice daily for 5 days in adults, or 2.2 mg/kg of body weight (up to 75 mg) twice daily for 5 days in children. These are available by prescription for the prevention and treatment of type A influenza (they are ineffective against type B). They are associated with several toxic effects and also contribute to emergence of resistance against them by the influenza virus type A.

Avian influenza A (H5N1, which exists in at least 8 subgroups, or “clades”) may be resistant to the adamantane drugs (rimantadine and amantadine), so would be treated with zanamivir or oseltamivir, the former in a dose of 75 mg and the latter in a dose of 150 mg by mouth twice a day for 10 days. This form of influenza is carried and spread by birds, notably poultry and perhaps wild birds. It has been found in other species, such as cats, tigers, leopards, pigs, ferrets, rabbits, rats, and emus, from where it might more rapidly mutate to a form more infectious to humans. Avian flu has a very aggressive profile, with a high (up to 60%) overall mortality rate in human victims. Infected humans show “typical” flu symptoms, followed rapidly by respiratory and multiorgan failure. There is little evidence for mild or asymptomatic human infections. With regard to protective masks, an N95 respirator mask is supposed to have at least a 95% filtration capability at filtering a 0.3 micron droplet, which carries the virus, but not the virus particles individually.