Viral Illnesses Abound This Season: Identifying the Culprits and How You Can Combat Them

from School Health Reporter, Winter 2003

Susan Dolan, RN, MS, CIC, Hospital Epidemiologist, The Children's Hospital, Department of Epidemiology

I am often asked by nurses in the school setting about various viral illnesses that may or may not be circulating in the community. Many times the name of the virus is not really particularly helpful clinically, as the child’s treatment course will not change since many viral illnesses require basic supportive care  (hydration, etc.) in the non-hospital setting. However, with so many viruses lurking in our midst year-round, I thought it might be helpful to highlight a few notorious culprits that are quite predictable and like to leave their mark in the fall, winter and early spring. The most common of these viruses typically affects either the respiratory or enteric system in many individuals, sometimes resulting in hospitalization. Many of these viruses can cause a variety of clinical syndromes. For example, a virus can also cause cold symptoms in one person while at the same time cause pneumonia in another person. Since there are numerous viruses circulating at any given time, we will focus on those that have a higher prevalence during what is often referred to as “viral season” (see Table 1).

Parainfluenza

There are three types of parainfluenza: Type I, Type II and Type III. The epidemiology of the Type I virus (the major cause of croup) is that it occurs biannually in the fall of odd-numbered years, so it will not be a major player again until the fall of 2003. There also is a parainfluenza Type II virus that we see only sporadically throughout the year, but it tends to cause less severe respiratory illness. Parainfluenza Type III virus occurs mostly in the late spring, but it can also be seen in the summer and early fall. This virus is a major cause of lower respiratory tract disease (e.g., bronchiolitis and pneumonia) in infants and manifests itself in children and adults as cold-like symptoms and laryngitis. We expect to see this virus surface in a few months as the other winter viruses settle down. All the parainfluenza viruses have a short incubation period, have a shedding period of a few days up to three weeks and spread via droplet transmission like most other respiratory viruses.

Influenza

By now you should have had your yearly influenza vaccine to protect you, and secondarily your students, from this severe illness. Remember that influenza is not just the “flu.”  It is a severe disease that occurs each year in the winter months and consists of the sudden onset of fever  (usually high) frequently accompanied by chills, headache, malaise, aching muscles/joints and a dry cough. Subsequently, sore throat, nasal congestion and cough symptoms increase. Many people confuse minor viral illnesses with influenza, calling any respiratory symptoms “the flu,” but anyone who has experienced this illness can vouch for the misery the flu can cause. We typically see influenza in December and January.  Occasionally, we may see a smaller spring outbreak from a different strain of influenza.

School-aged children are a group that gets hit hard with influenza each year. While most healthy people do not die from influenza, the very young, very old and those with medical conditions are at high risk for complications or even death from the virus.  Some of the high-risk children (and adults, too) include those with asthma, respiratory disease, cardiac anomalies, immunosuppression, transplants and prematurity. By vaccinating the community, we can decrease the impact of this virus on those high-risk school-aged children who are susceptible to more severe disease/complications  (CDC, April 2002).

Many people think the influenza vaccine will give them the “flu.” This is not the case, because the vaccine is made with killed virus and therefore is incapable of causing influenza. The most common side effect is soreness at the injection site that lasts one to three days.

A new intranasal flu vaccine was developed by the National Institutes of Health (NIH) and Aviron. This vaccine is believed to be more effective because the virus is adapted to growing at colder temperatures. This means the virus can infect the cooler upper respiratory tract, stimulating immunity but not causing disease in the warmer lungs. In a 1996-97 Aviron study (N = 1,602 children), 1 percent of those who received the nasal vaccine and 18 percent of the placebo group developed influenza (Belshe et al. 1998). The children also had fewer febrile illnesses, including 30 percent fewer episodes of febrile otitis media. If this vaccine receives FDA approval, it is expected to have a positive impact on the ease of administration (two nasal “sprays”) and prevention of the disease. Furthermore, results published in 1999 from a phase 3 effectiveness trial in 4,561 healthy, working adults showed that those who received the intranasal flu vaccine experienced reductions in illness-associated, missed work days and health-care provider visits, as well as prescription and over-the-counter medication use associated with illness (Nichol, 1999).

There are some antiviral medications on the market for the prevention and/or treatment of influenza.  Both Amantadine and Rimantadine are approved by the FDA for use in children and adults for prophylaxis against Influenza A infection. Therapy should be started as soon as possible after the onset of symptoms and can be continued for two to seven days depending on clinical improvement.  Amantadine is also approved for the treatment of influenza in children.  Amantadine and Rimantadine are not effective against Influenza B infections.  In 1999, the FDA approved two new antivirals for the treatment of influenza in patients who have been symptomatic for no more than two days. Zanamivir (Relenza®) and oseltamivir (Tamiflu“) have been shown to decrease the duration of flu related symptoms by one to one-and one-half days. Oseltamivir has been approved for prophylaxis in patients older than 13 years. Zanamivir has been approved for treatment of patients age seven years and older, while oseltamivir is approved for children age one year and older.

Respiratory Syncytial Virus (RSV)

RSV is the most important cause of bronchiolitis and pneumonia in infants and children. Our epidemiological “crystal ball” tells us that this year’s RSV season will be more spread out and less intense than last season. The season will begin earlier, have a milder peak and linger longer.  We can expect the RSV season to begin around the December holidays and peak in January and February here in Colorado .

Although a vaccine is not available for RSV, preventative therapies are being used in a select population of high-risk infants/children. The therapies are administered during the winter months with the intent of preventing the acquisition of the virus in this select population.

Rotavirus

Rotavirus is the single most common cause of diarrhea that requires medical attention in children less than two years of age but it can also affect school-aged children and adults.  It requires only a small inoculum of virus to make one ill and is spread by the fecal-oral route. This virus has an interesting pattern each year in that it typically begins in the Southwestern states in the fall and moves in a pattern over the United States until it reaches the Northeast by spring (Glass, et al., 1996). In Colorado , we typically see rotavirus during December and January.  In 1998, a vaccine for rotavirus was FDA-approved, but has since been removed from the market due to an association with intussusception post-vaccination.

Enterovirus

Enterovirus is another virus that shows up regularly at the end of the summer and peaks in early fall each year. Fever of unknown origin and other symptoms, which initially can mimic bacterial sepsis and meningitis are the most common presentations.  The 2002 season was less severe in comparison to some previous seasons we have experienced. The advent of the enterovirus PCR test, which is a more rapid diagnostic tool for this virus, has helped clinicians differentiate viral from bacterial cases in a more timely fashion and often shortens or prevents hospitalization.

Other Viruses

We tend to see rhinovirus and adenovirus year-round also, although there is some peak in the spring and fall with rhinovirus. This past fall, we experienced a fair amount of rhinovirusrelated illness in the community.  While rhinovirus is responsible for what we all refer to as the “common cold,” adenovirus can cause either respiratory or enteric symptoms or both. Adenovirus is a virus that is not very well tolerated by the immuno-compromised patient in particular.  Coronoviruses are a common cause of upper respiratory illness in adults and children and occasionally cause disease in the lower airway. On the other hand, corona virus-like particles  (CVLP), like torovirus, are noted for causing diarrhea.

Incubation, Transmission and Precautions

I often am consulted by school nurses regarding the incubation period as well as the shedding period for the various viruses. In general, the incubation period (the time from expo-sure to onset of illness) is a few days, with influenza having the shortest incubation period of one to three days. Another common question is, “How long is the person contagious?”  In the normal host, the contagious period is about one to two weeks.  However, the very young (neonates and infants), as well as the immuno-compromised individual can shed these viruses much longer.

We do know that most viruses are transmitted from one person to another by contact with the secretions and/or excretions of the infected person. An exception would be “airborne” viruses like measles and varicella (chickenpox). The typical respiratory viruses we have discussed earlier are spread via droplets expressed from the respiratory tract, as well as contact with contaminated surfaces and objects.

With one or more of these viruses circulating in the community at any given time, we know one thing for sure: Handwashing is still the number one way to prevent the spread of infection between students and staff.  In October 2002, the CDC published its “Guideline for Hand Hygiene in Health-Care Settings.” Although it is not specifically related to school settings, there is good information about the newer, waterless, hand hygiene products. In particular, there is strong evidence-based research to support the use of the alcohol hand rub products when hands are not visibly soiled. If you are considering introducing this product into your school, be sure to go to the Centers for Disease Control and Prevention (CDC)  Web site and familiarize yourself with this part of the document. Remember to protect your students, family and friends. And last but not least… protect yourself. Wash those hands!

Finally, if you are interested in knowing what viruses (and also pertussis)  are circulating in the community and at what frequency, visit The Children's Hospital Web site listed below and click on  “BUG WATCH.” This site is updated weekly by Children’s and is a quick and easy reference. If you would like “BUG WATCH” e-mailed to you each week, contact Carolyn Brock via e-mail at brock.carolyn@tchden.org and she will add you to the email distribution list.