I read with great interest the case reported by the authors [1] describing the unusual latency period in subacute scerosing panencephalitis (SSPE). The usual latency period of SSPE is 6-10 years from its onset as it is a slow virus neurodegenerative disorder. The exact factors and influences that allow the measles infection to persist are unclear, but may include several immunological factors [2]. Numerous alterations in M protein have been described in SSPE because of extensive point mutations in viral genome, possibly resulting in persistent viral infection [3].

Since it is a slow progressive neurodegerative disorder a latency period of two month is very unusual. Authors have not described the pathogenesis behind this unusual occurrence. Moreover CSF analysis shows only raised IgG levels with normal IgM levels but looking at short latency period there is more possibility of raised IgM levels instead of IgG measles antibody. Therefore this case is looking more likely a case of SSPE from congenital measles and in that case this latency becomes irrelevant. Serology of the mother can be helpful in these cases.

1. Saurabh K, Gupta R, Khare S, Sharma S. Atypical subacute sclerosing panencephalitis with short onset latency. Indian Pediatr. 2013;50:244-5.

2. Garg RK. Subacute sclerosing panencephalitis. J Neurol. 2008;255:1861-71.