Sneezing, scratchy throat, runny nose-everyone knows the first signs of a cold,
probably the most common illness known. Although the common cold is usually
mild, with symptoms lasting 1 to 2 weeks, it is a leading cause of doctor visits
and missed days from school and work. According to the Centers for Disease
Control and Prevention, 22 million school days are lost annually in the United
States due to the common cold.
In the course of a year, people in the United States suffer 1 billion colds,
according to some estimates.
Children have about 6 to 10 colds a year. One important reason why colds are
so common in children is because they are often in close contact with each other
in daycare centers and schools. In families with children in school, the number
of colds per child can be as high as 12 a year. Adults average about 2 to 4
colds a year, although the range varies widely. Women, especially those aged 20
to 30 years, have more colds than men, possibly because of their closer contact
with children. On average, people older than 60 have fewer than one cold a year.
More than 200 different viruses are known to cause the symptoms of the common
cold. Some, such as the rhinoviruses, seldom produce serious illnesses. Others,
such as parainfluenza and respiratory syncytial virus, produce mild infections
in adults but can precipitate severe lower respiratory infections in young
Rhinoviruses (from the Greek rhin, meaning “nose”) cause an estimated
30 to 35 percent of all adult colds, and are most active in early fall, spring,
and summer. More than 110 distinct rhinovirus types have been identified. These
agents grow best at temperatures of about 91 degrees Fahrenheit, the temperature
inside the human nose.
Scientists think coronaviruses cause a large percentage of all adult colds.
They bring on colds primarily in the winter and early spring. Of the more than
30 kinds, three or four infect humans. The importance of coronaviruses as a
cause of colds is hard to assess because, unlike rhinoviruses, they are
difficult to grow in the laboratory.
Approximately 10 to 15 percent of adult colds are caused by viruses also
responsible for other, more severe illnesses: adenoviruses, coxsackieviruses,
echoviruses, orthomyxoviruses (including influenza A and B viruses, which cause
flu), paramyxoviruses (including several parainfluenza viruses), respiratory
syncytial virus, and enteroviruses.
The causes of 30 to 50 percent of adult colds, presumed to be viral, remain
unidentified. The same viruses that produce colds in adults appear to cause
colds in children. The relative importance of various viruses in pediatric
colds, however, is unclear because it’s difficult to isolate the precise cause
of symptoms in studies of children with colds.
There is no evidence that you can get a cold from exposure to cold weather or
from getting chilled or overheated.
There is also no evidence that your chances of getting a cold are related to
factors such as exercise, diet, or enlarged tonsils or adenoids. On the other
hand, research suggests that psychological stress and allergic diseases
affecting your nose or throat may have an impact on your chances of getting
infected by cold viruses.
THE COLD SEASON
In the United States, most
colds occur during the fall and winter. Beginning in late August or early
September, the rate of colds increases slowly for a few weeks and remains high
until March or April, when it declines. The seasonal variation may relate to the
opening of schools and to cold weather, which prompt people to spend more time
indoors and increase the chances that viruses will spread to you from someone
Seasonal changes in relative humidity also may affect the prevalence of
colds. The most common cold-causing viruses survive better when humidity is
low-the colder months of the year. Cold weather also may make the inside lining
of your nose drier and more vulnerable to viral infection.
Symptoms of the common cold usually
begin 2 to 3 days after infection and often include
- Mucus buildup in your nose
- Difficulty breathing through your nose
- Swelling of your sinuses
- Sore throat
Fever is usually slight but can climb to 102 degrees Fahrenheit in infants
and young children. Cold symptoms can last from 2 to 14 days, but like most
people, you’ll probably recover in a week. If symptoms occur often or last much
longer than 2 weeks, you might have an allergy rather than a cold.
Colds occasionally can lead to bacterial infections of your middle ear or
sinuses, requiring treatment with antibiotics. High fever, significantly swollen
glands, severe sinus pain, and a cough that produces mucus, may indicate a
complication or more serious illness requiring a visit to your healthcare
You can get infected by cold
viruses by either of these methods.
- Touching your skin or environmental surfaces, such as telephones and stair
rails, that have cold germs on them and then touching your eyes or nose
- Inhaling drops of mucus full of cold germs from the air
There is no cure for the common cold, but you can get relief
from your cold symptoms by
- Resting in bed
- Drinking plenty of fluids
- Gargling with warm salt water or using throat sprays or lozenges for a
scratchy or sore throat
- Using petroleum jelly for a raw nose
- Taking aspirin or acetaminophen, Tylenol, for example, for headache or fever
A word of caution: Several studies have linked aspirin use to the
development of Reye’s syndrome in children recovering from flu or chickenpox.
Reye’s syndrome is a rare but serious illness that usually occurs in children
between the ages of 3 and 12 years. It can affect all organs of the body but
most often the brain and liver. While most children who survive an episode of
Reye’s syndrome do not suffer any lasting consequences, the illness can lead to
permanent brain damage or death. The American Academy of Pediatrics recommends
children and teenagers not be given aspirin or medicine containing aspirin when
they have any viral illness such as the common cold.
Over-the-counter cold medicines
Nonprescription cold remedies, including decongestants and cough
suppressants, may relieve some of your cold symptoms but will not prevent or
even shorten the length of your cold. Moreover, because most of these medicines
have some side effects, such as drowsiness, dizziness, insomnia, or upset
stomach, you should take them with care.
Nonprescription antihistamines may give you some relief from symptoms such as
runny nose and watery eyes which are commonly associated with colds.
Never take antibiotics to treat a cold because antibiotics do not kill
viruses. You should use these prescription medicines only if you have a rare
bacterial complication, such as sinusitis or ear infections. In addition, you
should not use antibiotics “just in case” because they will not prevent
Although inhaling steam may temporarily relieve symptoms of congestion,
health experts have found that this approach is not an effective treatment.
There are several ways you can keep yourself from getting a
cold or passing one on to others
HIV Infection and AIDS: An Overview
AIDS (acquired immunodeficiency syndrome) was first reported in the United
States in 1981 and has since become a major worldwide epidemic. AIDS is caused
by HIV (human immunodeficiency virus). By killing or damaging cells of the
body’s immune system, HIV progressively destroys the body’s ability to fight
infections and certain cancers. People diagnosed with AIDS may get
life-threatening diseases called opportunistic infections, which are caused by
microbes such as viruses or bacteria that usually do not make healthy people
More than 900,000 cases of AIDS have been reported in the United States since
1981. As many as 950,000 Americans may be infected with HIV, one-quarter of whom
are unaware of their infection. The epidemic is growing most rapidly among
minority populations and is a leading killer of African-American males ages 25
to 44. According to the Centers for Disease Control and Prevention (CDC), AIDS
affects nearly seven times more African Americans and three times more Hispanics
than whites. In recent years, an increasing number of African-American women and
children are being affected by HIV/AIDS. In 2003, two-thirds of U.S. AIDS cases
in both women and children were among African-Americans.
HIV is spread most commonly by having unprotected sex with
an infected partner. The virus can enter the body through the lining of the
vagina, vulva, penis, rectum, or mouth during sex.
HIV can infect anyone who practices risky behaviors such as
- Sharing drug needles or syringes
- Having sexual contact, including oral, with an infected person without using
- Having sexual contact with someone whose HIV status is unknown
HIV also is spread through contact with infected blood. Before donated blood
was screened for evidence of HIV infection and before heat-treating techniques
to destroy HIV in blood products were introduced, HIV was transmitted through
transfusions of contaminated blood or blood components. Today, because of blood
screening and heat treatment, the risk of getting HIV from such transfusions is
HIV is frequently spread among injection drug users by the sharing of needles
or syringes contaminated with very small quantities of blood from someone
infected with the virus.
It is rare, however, for a patient to give HIV to a health care worker or
vice-versa by accidental sticks with contaminated needles or other medical
Mother to child
Women can transmit HIV to their babies during pregnancy or birth.
Approximately one-quarter to one-third of all untreated pregnant women infected
with HIV will pass the infection to their babies. HIV also can be spread to
babies through the breast milk of mothers infected with the virus. If the mother
takes certain drugs during pregnancy, she can significantly reduce the chances
that her baby will get infected with HIV. If health care providers treat
HIV-infected pregnant women and deliver their babies by cesarean section, the
chances of the baby being infected can be reduced to a rate of 1 percent. HIV
infection of newborns has been almost eradicated in the United States due to
A study sponsored by the National Institute of Allergy and Infectious
Diseases (NIAID) in Uganda found a highly effective and safe drug for preventing
transmission of HIV from an infected mother to her newborn. Independent studies
have also confirmed this finding. This regimen is more affordable and practical
than any other examined to date. Results from the study show that a single oral
dose of the antiretroviral drug nevirapine (NVP) given to an HIV-infected woman
in labor and another to her baby within 3 days of birth reduces the transmission
rate of HIV by half compared with a similar short course of AZT
(Azidothymidine). For more information on preventing transmission from mother to
child, go to http://aidsinfo.nih.gov/guidelines.
Although researchers have found HIV in the saliva of infected people, there
is no evidence that the virus is spread by contact with saliva. Laboratory
studies reveal that saliva has natural properties that limit the power of HIV to
infect, and the amount of virus in saliva appears to be very low. Research
studies of people infected with HIV have found no evidence that the virus is
spread to others through saliva by kissing. The lining of the mouth, however,
can be infected by HIV, and instances of HIV transmission through oral
intercourse have been reported.
Scientists have found no evidence that HIV is spread through sweat, tears,
urine, or feces.
Studies of families of HIV-infected people have shown clearly that HIV is not
spread through casual contact such as the sharing of food utensils, towels and
bedding, swimming pools, telephones, or toilet seats.
HIV is not spread by biting insects such as mosquitoes or bedbugs.
Sexually transmitted infections
If you have a sexually transmitted infection (STI) such as syphilis, genital
herpes, chlamydial infection, gonorrhea, or bacterial vaginosis appears, you may
be more susceptible to getting HIV infection during sex with infected partners.
EARLY SYMPTOMS OF HIV INFECTION
If you are like many people, you will
not have any symptoms when you first become infected with HIV. You may, however,
have a flu-like illness within a month or two after exposure to the virus. This
illness may include
- Enlarged lymph nodes (glands of the immune system easily felt in the neck
These symptoms usually disappear within a week to a month and are often
mistaken for those of another viral infection. During this period, people are
very infectious, and HIV is present in large quantities in genital fluids.
More persistent or severe symptoms may not appear for 10 years or more after
HIV first enters the body in adults, or within 2 years in children born with HIV
infection. This period of “asymptomatic” infection varies greatly in each
individual. Some people may begin to have symptoms within a few months, while
others may be symptom-free for more than 10 years.
Even during the asymptomatic period, the virus is actively multiplying,
infecting, and killing cells of the immune system. The virus can also hide
within infected cells and lay dormant. The most obvious effect of HIV infection
is a decline in the number of CD4 positive T (CD4+) cells found in the blood-the
immune system’s key infection fighters. The virus slowly disables or destroys
these cells without causing symptoms.
As the immune system worsens, a variety of complications start to take over.
For many people, the first signs of infection are large lymph nodes or “swollen
glands” that may be enlarged for more than 3 months. Other symptoms often
experienced months to years before the onset of AIDS include
- Lack of energy
- Weight loss
- Frequent fevers and sweats
- Persistent or frequent yeast infections (oral or vaginal)
- Persistent skin rashes or flaky skin
- Pelvic inflammatory disease in women that does not respond to treatment
- Short-term memory loss
Some people develop frequent and severe herpes infections that cause mouth,
genital, or anal sores, or a painful nerve disease called shingles.