5 California Children Infected by Polio-Like Illness
Over a one-year period, five children in California developed a polio-like illness that caused severe weakness or paralysis in their arms and legs, a new case study reports.
In two of the children, their symptoms have now been linked with an extremely rare virus called enterovirus-68.
Like the poliovirus, which has been eradicated in the U.S. since 1979 thanks to the polio vaccine, strains of enterovirus in rare cases can invade and injure the spine.
These are the first reported cases of polio-like symptoms being caused by enterovirus in the United States. During the last decade, outbreaks of polio-like symptoms have been reported in children in Asia and Australia, and these infections have been associated with newly identified strains of enterovirus
"We think one reason why these cases may have occurred in California is that we are at the western-most part of the United States, so we may have had a higher circulation of the virus that was originally identified in Asia," said Dr. Emmanuelle Waubant, co-author of the case report and a neurologist at the University of California, San Francisco Medical Center. 
Although two of the children tested positive for enterovirus-68, the researchers were not able to identify the cause of muscle weakness and paralysis in the other three children.
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Enterovirus 68 is associated with respiratory illness and shares biological features with both the enteroviruses and the rhinoviruses
Received 19 December 2003.
Accepted 20 May 2004.
Enterovirus (EV) 68 was originally isolated in California in 1962 from four children with respiratory illness. Since that time, reports of EV68 isolation have been very uncommon. Between 1989 and 2003, 12 additional EV68 clinical isolates were identified and characterized, all of which were obtained from respiratory specimens of patients with respiratory tract illnesses.
These recent isolates, as well as the original California strains and human rhinovirus (HRV) 87 (recently shown to be an isolate of EV68 and distinct from the other human rhinoviruses), were compared by partial nucleotide sequencing in three genomic regions (partial sequencing of the 5′-non-translated region and 3D polymerase gene, and complete sequencing of the VP1 capsid gene). The EV68 isolates, including HRV87, were monophyletic in all three regions of the genome.
Human rhinovirus 87 (HRV87), which was isolated in 1963 in the same laboratory that isolated the original EV68 strains (Kapikian et al., 1971), is unique among the human rhinoviruses in its receptor usage (Uncapher et al., 1991). The prototype strain, Corn, is the only known example of HRV87.
Recent molecular and antigenic characterization has shown that HRV87-Corn is actually a strain of EV68, based upon cross-neutralization studies and comparison of partial capsid sequences (Blomqvist et al., 2002; Ishiko et al., 2002; Savolainen et al., 2002).
The origin of EV70 remains a mystery. It is most closely related genetically to EV68, a potential progenitor whose existence was known at the time of the global emergence of EV70 in the AHC pandemic of 1970; however, the relationship is not so close as to suggest a direct ancestral relationship. It has been hypothesized that EV70 may have emerged through an unknown mechanism from an animal reservoir (Yoshii et al., 1977).
The exclusive association of EV68 with respiratory disease, the acid lability of EV68 isolates and their poor growth at 37°C and the apparent mistyping of the HRV87-Corn strain demonstrate that the distinctions between the enteroviruses and the rhinoviruses are neither as clear nor as reliably determined as conventionally believed
We are indebted to Jane LaFlash, Wisconsin State Laboratory of Hygiene, and the laboratory staff in other state health departments for their efforts in isolating these viruses. We also thank Dean Erdman, Division of Viral and Rickettsial Diseases, CDC, for providing a stock of HRV87-Corn
While the exact cause (or causes) of these California cases remains unknown, a viral infection is strongly suspected, and high on the list of suspects are members of the ubiquitous non-polio enterovirus family of viruses or NPEVs (which includes Coxsackievirus A, Coxsackievirus B, Echoviruses & numerous other Enteroviruses).
According to the CDC, NPEVs cause 10 to 15 million – mostly mild and often asymptomatic – infections in the United States each year, primarily among infants, children, and teenagers. Fever, runny nose, sneezing, coughing, a skin rash or mouth blisters, and body and muscle aches are the most commonly reported symptoms.
EV-70 - Pandemic in 1969-71
Enterovirus type 70: the etiologic agent of pandemic acute haemorrhagic conjunctivitis
A new enterovirus, now classified as enterovirus type 70, was isolated from the conjunctiva of patients with acute haemorrhagic conjunctivitis during the 1971 epidemics that occurred in Japan, Singapore, and Morocco.
These epidemics were parts of a pandemic involving Africa (Algeria, Ghana, Morocco, Nigeria, and Tunisia), Asia (Cambodia, China (Province of Taiwan), Hong Kong, India, Indonesia, Japan, Malaysia, the Philippines, Singapore, and Thailand), and England during 1969-71.
A representative strain from each of the three epidemic areas was studied cooperatively. The strains exhibited the physicochemical characteristics of enteroviruses. Cross-neutralization tests showed that these viruses were distinct from all known human enterovirus immunotypes, but that they were antigenically closely related. The human origin of the viruses was demonstrated by the appearance of homologous neutralizing antibodies during convalescence in patients with acute haemorrhagic conjunctivitis.