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Non-polio Enterovirus Infections

Virology

Classification and Host Range

The enteroviruses comprise one class of the family Picornaviridae (table 1). They are distinguished from other picornaviruses by their acid stability. Enteroviruses are found in many mammalian and non-mammalian hosts. However, enteroviruses that infect humans represent a distinct group that are not found in other hosts.

Most human enteroviruses are subclassified into four subclasses.

Unlike rhinoviruses, enteroviruses maintain infectivity over a wide pH range (3-l0).

They are rapidly inactivated at temperatures >500C.

Pathogenesis of Enterovirus Infections Non-polio Enteroviruses Infections Aseptic Meningitis

Transmission

Infection results from ingestion of fecally contaminated material or, less commonly, via contact with respiratory secretions.

The incubation period is characteristically 3-5 days between infection and onset of non-specific symptoms.

Infection and Viral Dissemination

Initial sites of replication include both the pharynx and terminal ilium

Virus is shed from the upper respiratory tract for 1-3 weeks, Non-polio Enteroviruses Infections Aseptic Meningitis and from the feces for 38 weeks. The period of maximum communicability is during the first non-polio enteroviruses, aseptic meningitis Non-polio Enteroviruses Infections Aseptic Meningitis 2 weeks after infection.

Immunity to Infection

Immunity to enterovirus infection is serotype specific. Non-polio Enteroviruses Infections Aseptic Meningitis

Passive humoral antibody confers non-polio enteroviruses, aseptic meningitis protection from disease in Non-polio Enteroviruses Infections Aseptic Meningitis low titer, and from both infection and disease in high titer.

Humoral antibodies also have an important role in the immune Non-polio Enteroviruses Infections Aseptic Meningitis response to enterovirus infection. Patients with isolated B cell immunodeficiency are at Non-polio Enteroviruses Infections Aseptic Meningitis risk of prolonged, severe infections.

Epidemiology

Epidemic and Endemic Behavior

Seasonal patterns

Population immunity

Age and Socioeconomic Status

1. Incidence rates of infection and disease are inversely proportional to age. Infants <12 months have the highest incidence of disease

2. Rates of infection and disease are also higher among children of lower socioeconomic classes.

C. Transmission

1. Both direct person-to-person transmission, and indirect transmission (via contaminated fomites, food, and water) probably occurs.

2. Transmission is most efficient in households and families. Secondary attack rates for infection of 30-90% within households.

V. Laboratory Diagnosis

A. Virus Isolation. Cell culture is labor intensive and expensive.

B. Polymerase Chain Reaction (PCR)

1. PCR has superior sensitivity compared to cell culture for identification of enteroviruses in CSF.

2. Experience with other specimens is more limited. PCR compares favorably to culture for throat and serum specimens, but may be