Rotavirus: The Virus on Wheels

Rotavirus is a seasonal virus thatshould not be underestimated. Itcauses acute gastroenteritis (irritatedor inflamed stomach or intestinalsurface) in children 5 years of age oryounger, leading to severe cases of dehydrationin children 3 to 35 months ofage.^1-8

Viral Nature

In 1973, Australian scientists led byRuth F. Bishop looked at a sample of duodenalmucosa taken from children withacute nonbacterial gastroenteritis. Theinvestigators observed virus particleswith a diameter of ~70 nm, which werelater named rotavirus.⁹ Rotavirus is anRNA virus. It belongs to the Reoviridaefamily and got its name from its wheelappearance (Latin rota = wheel).

Rotavirus has 7 antigenic groups: A, B,C, D, E, F, and G. The Group A virus hasmultiple strains, with 3 protein layers anda diameter of 70 to 75 nm. It causesrotavirus diarrhea in children in theUnited States. Groups B and C affectadults, causing gastroenteritis.^10-12

Clinical Presentation

In the United States, rotavirus appearsat the end of the fall/beginning of thewinter (November-December) in thesouthwestern part of the country. Closerto the middle of spring (April-May), itappears in the northeastern regions ofthe country.

Children show symptoms in ~2 days,once they are infected with rotavirus.Thesymptoms are fever, nausea, vomiting,stomach and abdominal pain, waterydiarrhea, and (most dangerous) dehydration.Symptoms can last for 3 to 9days.^13,14

Pathology

Rotavirus spreads between peopleby means of the fecal-oral routeof transmission. Once it is in thebody, the virus starts to infect thecells constituting the small intestinalvilli. Normally, these cells takepart in processes occurring in theintestine, such as the absorption offluids and electrolytes and the breakupof carbohydrates. Infection of these cellsprimarily causes malfunctions in thedecomposition process of carbohydratesand fluid loss from the intestine.

Bishop found unusually low levels oflactase, maltase, and sucrase enzymes.⁹These enzymes are made in the smallintestine. Lactase, a glycoside hydrolase,has a role in the hydrolysis of the disaccharidelactose. A deficiency of thisenzyme leads to lactose intolerance.Maltase plays a role in the hydrolysis ofmaltose. Sucrase is an enzyme that carriesthe hydrolysis of sucrose to fructoseand glucose. The diminished secretion ofsucrase leads to the condition known assucrose intolerance. This condition isdescribed as excessive gas productionand often diarrhea. Furthermore, rotavirusinitiates physiologic changes in thevillus epithelium, leading to a decrease inabsorptive properties and further worseningof the condition.¹⁵

Risk Factors

Experimental data have shown 2 mainrisk factors for rotavirus gastroenteritis.They are (1) contact with persons havinggastroenteritis and (2) poor food-handlinghygiene in the household.¹⁶ Youngage (6 months -2 years) is another riskfactor. Furthermore, premature infantsand children with weakened immunesystems are the most defenselessgroups.¹¹

Diagnostic Tools

Every child infected with rotavirusexcretes10⁹ to 10¹⁰ viralparticles for each gram of feces. Patients'stool samples are chosen for analysis.The samples are tested by enzymelinkedimmunosorbent assay and enzymeimmunoassay. To generate results,these assays require at least 10⁴ to 10⁶viral particles. They both are Group Aspecific.In the case of a positive result,IgM and IgA rotavirus is found to be presentin the infected patient's stool.^17-22

Prophylaxis

RotaTeq (Merck) rotavirus vaccine is alive human and bovine pentavalent vaccine.This vaccine consists of G1, G2, G3,G4, and P1 proteins aiming at rotavirusserotypes, which are responsible for>90% of cases of nonbacterial, rotavirusrelatedgastroenteritis in the UnitedStates.²³ RotaTeq is indicated for the prophylaxisof viral gastroenteritis due torotavirus. This vaccine is given accordingto the following schedule:

• 2 mL (entire pouch) orally at 2months (first dose between 6 and 12weeks of age)
• 4 months (second dose between 10and 22 weeks of age)
• 6 months (third and last dosebetween 14 and 32 weeks of age)
• All 3 doses by the age of 32 weeks(per the American College of InternationalPhysicians recommendations)

The most common side effects documented after the administration of thisvaccine are diarrhea and vomiting. WhenRotaTeq vaccine came on the market,the rates of intussusception associatedwith its usage were similar to the rateswith placebo. On February 13, 2007, however,the FDA issued a Public HealthNotification informing health care providersabout an additional 28 cases ofintussusception since the vaccine wasmarketed.²⁴ Therefore, caution should beexercised while administering RotaTeq tothe pediatric population with gastrointestinaldisorders.

Prevention

Breast milk helps infants fight rotavirus.Specifically, glycoproteins such asmucin and lactadherin were found inmothers'breast milk and were found tobe helpful in the fight against rotavirus.IgA antibodies transmitted with breastmilk to the baby give immunity againstrotavirus for up to 4 months.^25-29

Treatment

The treatment decision is made bythe pediatrician. If the physician decidesto keep a sick child at home, oral rehydrationtherapy would be indicated.Pedialyte (Ross) is an oral product withlow osmolality. It is used in infants andchildren to prevent dehydration causedby diarrhea and vomiting. The main constituentsof Pedialyte are water andimportant electrolytes such as sodium,potassium, and chloride. This productreplaces water and electrolytes lostwhile children are vomiting and havingdiarrhea.

The total daily volume requirement foradministered Pedialyte is based on age(excluding age of less than 1 week) andweight.³⁰ If the physician decides that achild should be brought to the hospital'semergency room, then the patient willreceive fluid rehydration via the intravenousroute.

The Pharmacist's Role

The pharmacist can play a key rolein caring for patients infected withrotavirus. The pharmacist shouldinform parents of the key points inhome care for a child infected withrotavirus. Parents always should watchout for basic symptoms of dehydration,which include dry diapers, dry and coolskin, dry mouth and tongue, sunkeneyes, and extreme thirst.

Parents should consult the pediatricianas to whether they should still feedtheir baby with formula. Furthermore,parents should be very choosy about theliquids they give to a baby who hasrotavirus. They should avoid giving hyperosmolardrinks, such as sports drinks,commercial soft drinks, and commercialsoup; use of these products may lead tohypernatremia. Likewise, an excessivefree-water intake may lead the baby tothe hyponatremic state. Antiemetic andantidiarrheal medications generallyshould be avoided unless recommendedby the pediatrician.

Important information to give parentsis that they should protect other babies,if any, in the family by following a goodhand-washing technique, or by avoidingplaying with sick children. Parents shouldbe ready to inform the physician on thedaily progress on the condition of a sickbaby. See the sample log in the Table tohelp parents in collecting information fortheir pediatrician.

Likewise, in the hospital, pharmacistsshould follow and inform caregiversabout any changes in the hemodynamicstatus of their patients.

Dr. Motylev is a pharmacy managerin the hospital setting.

References

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3. Centers for Disease Control and Prevention. Rotavirus Vaccine for the Preventionof Rotavirus Gastroenteritis Among Children: Recommendations of the AdvisoryCommittee on Immunization Practices (ACIP). MMWR Morb Mortal Wkly Rep.1999;48(RR-2):1-24.

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24. FDA Public Health Notification: Information on RotaTeq and Intussusception.Available at: www.fda.gov/cber/safety/phnrota021307.htm.

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27. Yolken RH, Peterson JA, Vonderfecht SL, et al. Human milk mucin inhibitsrotavirus replication and prevents experimental gastroenteritis. J Clin Invest.1992;90(5):1984-1991.

28. Newburg DS, Peterson JA, Ruiz-Palacios GM, et al. Role of human-milklactadherin in protection against symptomatic rotavirus infection. Lancet.1998;351:1160-1164.

29. Pickering LK, Morrow AL, Herrera I, et al. Effect of maternal rotavirusimmunization on milk and serum antibody titers. J Infect Dis. 1995;172:723-728.

30. Pedialyte. Physicians Desk Reference. 60th ed. Montvale, NJ: Thompson PDR;2006.