Over the last year more than 100 U.S. children have been affected by a mysterious paralysis called acute flaccid myelitis.
The sudden development of muscle weakness or paralysis in children’s arms or legs was initially linked to enterovirus D68 (EV-D68). However, only 20 percent of children with paralysis tested positive for EV-D68 and even in these cases it was not clear if EV-D68 was really the cause of the children’s condition.
In a new study, which will be published in the October issue of the Emerging Infectious Diseases journal, enterovirus C105 (EV-C105), which belongs to the same species (enterovirus C) as poliovirus, was detected in a 6-year old girl with paralysis. It has so far not been proven that EV-C105 was really the cause of the girl’s paralysis, but a new discovery proposes that other viruses besides EV-D68 may be involved in the U.S. children’s paralysis outbreak.
EV-C105 was first identified in late 2010 in the Democratic Republic of Congo and this 6-year old girl was the first reported case infected with this virus in the U.S. As EV-C105 is relatively new and is hard to detect, researchers suggest that it may not have been recognized in other cases during the outbreak. In this study the virus was identified using sequence analysis of the viral protein 1 capsid gene isolated from a nasopharyngeal swab.
Enteroviruses can cause paralysis, however it is not very common (except for polioviruses). Enterovirus D68 generally targets the respiratory system and causes flu-like symptoms, but it can enter the nervous system and may cause muscle weakness or paralysis.
In the current paralysis cases EV-D68 and EV-C105 have been detected in the respiratory tract but have not been found in the spinal fluid of affected children, which means that they did not necessarily cause paralysis in these cases. To more definitively link these cases of paralysis with the enterovirus, researchers would need to find the virus in spinal fluid.
At least two possible viruses have been found so far in the children’s specimens which may be the cause of paralysis in this outbreak. However, a more systematic diagnostic approach is needed to identify the real reason for paralysis occurring in the affected children.
By Katarina Kovac, PhD, Product Manager, BioSistemika LLC