Rotavirus
By: Daisy Rahman
Tags: Vaccines, Treatment, Rotavirus, Symptoms, Diarrhea

Rotavirus

It is a genus of double-stranded RNA viruses in the familyReoviridae. Rotaviruses are the most common cause of diarrhoeal disease among infants and young children. Nearly every child in the world is infected with rotavirus at least once by the age of five. Immunity develops with each infection, so subsequent infections are less severe; adults are rarely affected. There are ten species of the genus, referred to as A, B, C, D, E, F, G, H, I, and J. RotavirusA, the most common species causes more than 90% of rotavirus infections in humans.

Rotavirus Symptoms

❖ Symptoms:

Rotaviral enteritis is a mild to severe disease characterized by nausea, vomiting, watery diarrhea, and low-grade fever. Once there is an incubation period of about two days before symptoms appear. The period of illness is acute. Symptoms often start with vomiting, followed by four to eight days of profuse diarrhea. Dehydration is more common in rotavirus infection than in most of those caused by bacterial pathogens and is the most common cause of death related to rotavirus infection. Rotavirus A infections can occur throughout life: the first usually produces symptoms, but subsequent infections are typically mild or asymptomatic, as the immune system provides some protection. Consequently, symptomatic infection rates are highest in children under two years of age and decrease progressively towards 45 years of age. The most severe symptoms tend to occur in children six months to two years of age, the elderly, and those with immunodeficiency. Due to immunity acquired in childhood, and most adults are not susceptible to rotavirus; gastroenteritis in adults usually has a cause other than rotavirus, but asymptomatic infections in adults may maintain the transmission of infection in the community. There is some evidence to suggest blood group secretor status and the predominant bacteria in the gut can impact the susceptibility to infection by rotaviruses.

Vaccine

❖Treatment:

Treatment of acute rotavirus infection is nonspecific and involves managing symptoms and, most importantly, If untreated, management of dehydration. Children can die from the resulting severe dehydration. Depending on the severity of diarrhea, treatment consists of oral rehydration therapy, during which the child is given extra water to drink that contains specific amounts of salt and sugar. In 2004, the World HealthOrganization (WHO) and UNICEF recommended the use of low-osmolarity oral rehydration solution and zinc supplementation as a two-pronged treatment of acute diarrhea. Some infections are serious enough to warrant hospitalization where fluids are given by intravenous therapy or nasogastric intubation, and the child’selectrolytes and blood sugar are monitored. Rotavirus infections rarely cause other complications, and for a well-managed child, the prognosis is excellent. Probiotics have been shown to reduce the duration of rotavirus diarrhea, and according to the European. Society for Pediatric Gastroenterology “effective interventions include administration of specific probiotics such as Lactobacillusrhamnosus or Saccharomyces boulardii,diosmectite or racecadotril.”

❖Properties:

Replication: Occurs in the cytoplasm of the infected cell.

Rotavirus contains an RNA-dependent RNA polymerase and other enzymes capable of producing capped RNA transcripts

• Rotavirus do not grow in cell line culture Rotaviruses are inactivated by-

• Heating to 100°C

• Treatment with acid (pH❤),

• Glutaraldehyde (3%),

• Phenol,

• Formalin,

• Chlorine

• Alcohol (70%)

❖ Serotypes:

The development and implementation of safe and effective vaccines to prevent the enormous health burden of rotavirus-the associated disease is a global public health goal. Humanrotaviruses, the major aetiological agents of severe infantile diarrhea worldwide, display surprisingly diverse and complexserotypes specificities. Ten VP7 serotypes and 7 VP4 serotypes have so far been detected. An increasing number of observations, obtained from analyses of• natural rotavirus infections in infants and young children,• experimental rotavirus infections in laboratory animals,and• extensive rotavirus vaccine field trials performed in different populations of various parts of the world appear to support the concept that serotype-specific antibodies to rotaviruses play an important role in protection against rotavirus-associated illnesses. Thus, the first licensed rotavirus vaccine (RRV-based quadrivalent vaccine) was designed to cover the epidemiologically important VP7serotype 1, 2, 3, and 4

❖Pathogenesis:

Rotavirus infection can result in asymptomatic or symptomatic infection. The outcome of infection is affected by both viral and host factors. the most prominent host factor that affects the clinical outcome of infection is age. Thus, neonates infected with rotavirus rarely have symptom aticdisease; this protection is thought to be mediated primarily by transplacental transfer of maternal antibodies ductions in these antibodies coincide with the age of maximum susceptibility of infants to severe rotavirus-induced disease (3 mos to 2 years). Rotavirus can infect adults, but the severe symptomatic disease is relatively uncommon and can result from infections with an unusual virus strain or extremely high doses of virus. Virus virulence is related to properties of the proteins encoded by a subset of the 11 viral genes. Virus virulence is multigenic and has been associated with genes 3, 4, 5, 9, and 10. The basis for the involvement of these genes is only partially understood. Gene 3 encodes the capping enzyme that affects levels of viral RNA replication; genes 4 and 9produce the outer capsid proteins required to initiate infection. Gene 5codes for a protein (NSP1) function as s to regulate calcium homeostasis, virus replication, and as an enterotoxin. Diarrhea is the main clinical manifestation of rotavirus infection in infants and young children. A hallmark of viral-induced diarrhea that distinguishes it from bacterial-induced diarrhea is that little inflammation is seen in infected intestines. Rotavirus primarily infects intestinal villus enterocytes, and crypt cells are spared. Our understanding of disease pathogenesis is based primarily on studies in a variety of animal models. Disease pathogenesis is multifactorial and malabsorptive diarrhea occurs due to virus-mediated destruction of absorptive enterocytes, virus-induced downregulation of absorptiveenzymes’ expression, and functional changes in tight junctions between enterocytes that lead to paracellular leakage.