As enterovirus 71 continues to gain significance as an important public
health problem causing serious clinical illness, death and long-term neurologic
and psychiatric disorders in children, researchers explored the clinical
features, pathogenesis and transmission of the disease as well as management
strategies.
Reports of enterovirus 71 (EV71) outbreaks in Australia, Canada, Hong
Kong, Japan, Malaysia and Taiwan reviewed by the researchers revealed that
although patients often present with dermatologic symptoms such as
hand-foot-and-mouth disease and herpangina, central nervous system involvement
can lead to symptoms as severe as brain stem encephalitis, aseptic meningitis,
acute flaccid paralysis and pulmonary edema. Acute respiratory diseases may
also occur.
Epidemiologic data gathered from March 1998 to December 2007 via a
sentinel surveillance system established by the Taiwan CDC indicated that most
severe cases of hand-foot-and-mouth disease and herpangina occurred in children
younger than 4 years, with the majority (75%) occurring in children 2 years or
younger.
Lack of EV71–specific antibodies in children likely plays a role in
the prevalence of the disease, according to the researchers, as data from a
1998 Taiwan epidemic showed that antibody levels among infants and children
dropped from 7% to 11% down to 3% to 4% from 1994 to 1997.
Additional viral surveillance from the Taiwan CDC showed that a variety
of enteroviruses accounted for severe infections in the country from 1998 to
2007, including EV71 (17%), coxsackievirus A6 (5%), A10 (5%), A16 (24%) and B3
(10%) as well as echovirus 6 (6%) and 4 (5%). However, EV71 was most commonly
isolated from patients with encephalitis and pulmonary edema/hemorrhage (93%)
between 1998 and 2005 compared with patients who had aseptic meningitis.
"The data indicate that large numbers of other enteroviruses, especially
coxsackievirus A16, cocirculated and that their infections were a major
contributor to hand-foot-and-mouth disease/herpangina during EV71 epidemics in
Taiwan," the researchers wrote. "However, EV71 was responsible for almost all
of the complications of hospitalized patients, particularly those that led to
death."
Long-term neurologic and psychiatric disorders have also been linked to
EV71 infections with CNS involvement, according to the researchers. Patients
who experienced poliomyelitis-like syndrome, encephalomyelitis and
cardiopulmonary failure as a result of EV71 infection often experienced limb
weakness, atrophy and neurodevelopmental disorders, data from a long-term
follow-up study involving 142 children indicated. Researchers from a separate
study also found higher rates of attention-deficit/hyperactivity
disorder–related symptoms among 86 children with EV71 CNS involvement
(20%) than among a control group of 172 children (3%).
Although no specific therapies are currently approved for treating
enteroviral infections, a variety of antiviral, steroidal and IV immunoglobulin
therapies including pyridyl imidazolidinone, milrinone and ribavirin have been
used to treat these infections but have not been studied in randomized,
placebo-controlled trials.
Lee TC. Pediatr Infect Dis J. 2009;28:904-910.