INTRODUCTION: subacute sclerosing panencephalitis (SSPE) is a late, rare and 
usually fatal complication of measles infection. Although a very high incidence 
of SSPE in Papua New Guinea (PNG) was first recognized 20 years ago, estimated 
measles vaccine coverage has remained at ≤ 70% since and a large measles 
epidemic occurred in 2002. We report a series of 22 SSPE cases presenting 
between November 2007 and July 2009 in Madang Province, PNG, including localized 
clusters with the highest ever reported annual incidence.
METHODOLOGY/PRINCIPAL FINDINGS: as part of a prospective observational study of 
severe childhood illness at Modilon Hospital, the provincial referral center, 
children presenting with evidence of meningo-encephalitis were assessed in 
detail including lumbar puncture in most cases. A diagnosis of SSPE was based on 
clinical features and presence of measles-specific IgG in cerebrospinal fluid 
and/or plasma. The estimated annual SSPE incidence in Madang province was 
54/million population aged <20 years, but four sub-districts had an incidence 
>100/million/year. The distribution of year of birth of the 22 children with 
SSPE closely matched the reported annual measles incidence in PNG, including a 
peak in 2002.
CONCLUSIONS/SIGNIFICANCE: SSPE follows measles infections in very young PNG 
children. Because PNG children have known low seroconversion rates to the first 
measles vaccine given at 6 months of age, efforts such as supplementary measles 
immunisation programs should continue in order to reduce the pool of non-immune 
people surrounding the youngest and most vulnerable members of PNG communities.