Deterrence/Prevention
Reovirus
No specific treatment or prevention measures are recommended for reovirus infections in humans because of the lack of definitive association with disease. Vaccine preparations are available for veterinary use.
Colorado tick fever
CTF is best prevented by avoiding contact with the wood tick. This may be achieved by wearing suitable clothing to decrease the possibility of an infected tick becoming attached to the body. Instruct patients and family members to inspect the scalp and neck and the sleeve, belt, trouser, and sock line areas carefully for ticks several times each day and to remove any ticks that may be found to prevent them from becoming imbedded in the skin.
Repellent can be sprayed on clothing or applied to exposed skin in adults. Remind patients and family members to tuck long pants into socks, to wear shirts tucked in, and to inspect clothing and skin frequently for attached ticks. Identifying ticks on light-colored clothing is easier. Persons with documented CTF should be prohibited from blood donation until the viremia, which often is prolonged, has cleared.
Education is the best means by far of preventing the disease. Periodically remind the public of the clinical features of CTF and the ticks that transmit the causative agents. Because of the generally benign nature of the disease, attempts at active immunization do not appear to be indicated, and extensive specific measures to rid any large area of the United States of the wood tick do not appear to be warranted.
Rotavirus
Rotavirus typically infects children in the first 3 years of life during epidemics that occur in the winter in temperate climates. In developed countries with ready access to medical care and careful attention to oral and intravenous rehydration, fatalities are relatively rare, but rotavirus illness is still an important cause of morbidity. In developing countries, the impact of the disease is much more striking, with estimates that rotavirus may be the leading cause of childhood mortality in many countries.
In view of the fecal-oral route of transmission, wastewater treatment and sanitation are significant control measures.
Responses to the vaccine are generally assessed by evaluating the rise in serum antibody levels. However, several rotavirus vaccine trials indicate that clinical efficacy rates are higher than seroconversion rates, suggesting that serum antibodies are not sensitive enough indicators of immune responses and that assessment of local immunity may prove more reliable.
Studies addressing the role of serum antibody as a predictor of susceptibility to infection and illness have yielded conflicting results because monitoring of serum antibody responses may underestimate mucosal antibody by as much as 200%.
Precedents for using animal rotavirus strains as vaccine candidates include (1) the antigenic relatedness between human and animal rotaviruses and (2) evidence for the stimulation of heterologous protective immunity using one strain of rotavirus as an immunogen. For example, calves infected in utero with calf rotavirus developed resistance to challenge with HRV.
A rhesus rotavirus-tetravalent vaccine (RRV-TV, Rotashield) was licensed for use in the United States in August 1998. The vaccine consists of a quadrivalent formulation incorporating the VP7 neutralization specificity of each of the 4 clinically important serotypes with the attenuation phenotype of rhesus rotavirus.
The rhesus rotavirus–based quadrivalent vaccine was very successful in preventing severe rotavirus diarrhea in 2 trials in the United States and in one in Finland, with protection rates of 80-91%. In developing countries, its efficacy has been less impressive.
In Peru and Brazil, the efficacy of RRV-TV afforded only 20% and 35% protection respectively for any rotavirus gastroenteritis and 50-60% protection for severe rotavirus gastroenteritis. A febrile reaction occurred in about 30% of those vaccinated in Finland. Although most reactions were mild and clinically insignificant, the finding is an important part of the total clinical profile of the vaccine. In a United States multicenter trial, only 7% of vaccine recipients and 4% of placebo recipients had fever during the 5 days after the first vaccination. On July 16, 1999, the Centers for Disease Control and Prevention recommended that health care providers suspend use of the licensed RRV-TV (RotaShield, Wyeth Laboratories, Inc, Marietta, Pennsylvania) in response to 15 cases of intussusception. [32]
The risk of intussusception following RotaShield immunization is estimated to be 1 in 10,000-32,000. [33] The risk is highest during the 3-14 days following receipt of the first dose of vaccine. Infants older than 3 months at the time of the first dose of vaccine are at increased risk of intussusception. Although debate continues surrounding the exact quantitation of risk of intussusception, it is accepted as a rare adverse event.
Several rotavirus vaccines are now marketed in the United States. The orally administered live-virus vaccines exhibit similar safety characteristics. RotaTeq is a pentavalent vaccine that contains 5 live reassortant rotaviruses and is administered as a 3-dose regimen against G1, G2, G3, and G4 serotypes, the 4 most common rotavirus group A serotypes. RotaTeq also contains attachment protein P1A (genotype P[8]). Rotarix protects against rotavirus gastroenteritis caused by G1, G3, G4, and G9 strains and is administered as a 2-dose series in infants aged 6-24 weeks.
Complications
Reovirus
Rare cases of reovirus-induced neurologic disease in humans, including encephalitis and meningitis, have been reported. A 10-month-old infant with encephalitis, pneumonitis, myocarditis, and hepatitis was reported in whom reovirus serotype 1 was isolated from stool specimens and postmortem brain tissue. Tillotson and Lerner (1967) reported a 5-year-old girl who had extensive pneumonia and died after 15 days of illness. [16]
Joske and associates (1964) noted a 10-month-old girl who died after a respiratory illness of 4 days' duration. [17] Reovirus type 1 was recovered from the stool and brain of this child, and postmortem study revealed interstitial pneumonia, myocarditis, hepatitis, and encephalitis.
Colorado tick fever
In a few cases, complications such as encephalitis, aseptic meningitis, and hemorrhage have been reported. Other associated syndromes include pericarditis, epididymoorchitis, rheumatic fever syndrome, and atypical pneumonitis. The association of hepatitis with CTF also has been described.
Rotavirus
Rotavirus infections are associated with aseptic meningitis, necrotizing enterocolitis, acute myositis, hepatic abscess, pneumonia, Kawasaki disease [26] , SIDS [34] , and Crohn disease.
Prognosis
Reovirus and CTF infections
Reovirus and CTF infections are usually benign diseases with excellent prognosis.
Rotavirus
In developed countries with ready access to medical care and careful attention to oral and intravenous rehydration, fatalities are relatively rare, but rotavirus illness is still an important cause of morbidity.
In developing countries, the impact of the disease is much more striking, with estimates that it may be the leading cause of childhood mortality in many countries.
Patient Education
Because reovirus and rotavirus infections occur by fecal-oral transmission, wastewater treatment and sanitation are significant control measures.
Colorado tick fever: Education is by far the best means of preventing the disease. The public should be periodically reminded of the clinical features of CTF and the ticks that transmit the causative agents. Repellents can be sprayed on clothing or applied to exposed skin. Remind patients and family members to tuck long pants into socks, to wear shirts tucked in, and to inspect clothing and skin frequently for attached ticks. Identifying ticks on light-colored clothing is easier.
For excellent patient education resources, visit eMedicineHealth's Children's Health Center. Also, see eMedicineHealth's patient education articles Ticks and Sudden Infant Death Syndrome (SIDS).
