Respiratory Tract Infections
Respiratory tract infections affect the nose, throat, and airways and may be caused by any of several different viruses.
Children develop on average six viral respiratory tract infections each year. Viral respiratory tract infections include the common cold and influenza (see Section 17, Chapter 198 and Section 17, Chapter 198). Doctors often refer to these as upper respiratory infections (URIs), because they produce symptoms mainly in the nose and throat. In small children, viruses also commonly cause infections of the lower respiratory tract--the windpipe, airways, and lungs. These infections include croup, bronchiolitis, and pneumonia. Children sometimes have infections involving both the upper and lower respiratory tracts.
In children, rhinoviruses, influenza viruses (during annual winter epidemics), parainfluenza viruses, respiratory syncytial virus (RSV), and certain strains of adenovirus are the main causes of viral respiratory infections.
Most often, viral respiratory tract infections spread when a child's hands come into contact with nasal secretions from an infected person. These secretions contain viruses. When the child touches his mouth, nose, or eyes, the viruses gain entry and produce a new infection. Less often, infections spread when a child breathes air containing droplets that were coughed or sneezed out by an infected person. For various reasons, nasal or respiratory secretions from children with viral respiratory tract infections contain more viruses than those from infected adults. This increased output of viruses, along with typically lesser attention to hygiene, makes children more likely to spread their infection to others. The possibility of transmission is further enhanced when many children are gathered together, such as in childcare centers and schools. Contrary to what people may think, other factors, such as becoming chilled, wet, or tired, do not cause colds or increase a child's susceptibility to infection.
Symptoms and Complications
When viruses invade cells of the respiratory tract, they trigger inflammation and production of mucus. This situation leads to nasal congestion, a runny nose, scratchy throat, and cough, which may last up to 14 days. Fever, with a temperature as high as 101 to 102° F, is common. The child's temperature may even rise to 104° F. Other typical symptoms in children include decreased appetite, lethargy, and a general feeling of illness (malaise). Headaches and body aches develop, particularly with influenza. Infants and young children are usually not able to communicate their specific symptoms and just appear cranky and uncomfortable.
Because newborns and young infants prefer to breathe through their nose, even moderate nasal congestion can create difficulty breathing. Nasal congestion leads to feeding problems as well, because infants cannot breathe while suckling from the breast or bottle. Because infants are unable to spit out mucus that they cough up, they often gag and choke.
The small airways of young children can be significantly narrowed by inflammation and mucus, making breathing difficult. These children breathe rapidly and may develop a high-pitched noise heard on breathing out (wheezing) or a similar noise heard on breathing in (stridor). Severe airway narrowing may cause children to gasp for breath and turn blue (cyanosis). Such airway problems are most common with infection caused by parainfluenza viruses and RSV; affected children need to be seen urgently by a doctor.
Some children with a viral respiratory tract infection also develop an infection of the middle ear (otitis media) or the lung tissue (pneumonia). Otitis media and pneumonia may be caused by the virus itself or by a bacterial infection that develops because the inflammation caused by the virus makes tissue more susceptible to invasion by other germs. In children with asthma, respiratory tract infections often lead to an asthma attack.
Diagnosis
Doctors and parents recognize respiratory tract infections by their typical symptoms. Generally, otherwise healthy children with mild upper respiratory tract symptoms do not need to see a doctor unless they have trouble breathing, are not drinking, or have a fever for more than a day or two. X-rays of the neck and chest may be taken in children who have difficulty breathing, stridor, wheezing, or audible lung congestion. Blood tests and tests of respiratory secretions are rarely helpful.
Prevention and Treatment
The best preventive measure is practicing good hygiene. A sick child and the people in the household should wash their hands frequently. In general, the more intimate physical contact (such as hugging, snuggling, or bed sharing) that takes place with an ill child, the greater the risk of spreading the infection to other family members. Parents must balance this risk with the need to comfort an ill child. Children should stay home from school or childcare until the fever is gone and they feel well enough to attend.
Influenza is the only viral respiratory infection preventable by vaccination. Children with heart or lung disease (including asthma), diabetes, kidney failure, or sickle cell disease should receive the vaccine. Additionally, children whose immune system is compromised (including children with HIV infection and those undergoing chemotherapy) should receive the vaccine.
Antibiotics are not necessary to treat viral respiratory tract infections. Children with respiratory tract infections need additional rest and increased fluids. Acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, can be given for fever and aches. School-aged children may take a non-prescription decongestant for bothersome nasal congestion, although the drug often does not help. Infants and younger children are particularly sensitive to the side effects of decongestants and may experience agitation, confusion, hallucinations, lethargy, and rapid heart rate. In infants and young children, congestion may be relieved somewhat by using a cool-mist vaporizer to humidify the air and by suctioning the mucus from the nose with a rubber suction bulb.
Doctors may give certain children at high risk of developing a severe RSV infection monthly injections of palivizumab, which contains antibodies against RSV. Children who receive palivizumab are less likely to need hospitalization, but doctors are not sure whether this treatment prevents death or serious complications.
Children who have difficulty breathing are taken to a hospital. Depending on their condition, doctors may treat them with oxygen and drugs, such as albuterol or epinephrine, to open the airways (bronchodilators). Ribavirin is sometimes given to children with severe RSV pneumonia; however, the benefit of this drug is not clear.
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