Investigation of Japanese encephalitis virus as a cause of acute encephalitis in southern Pakistan, April 2015-January 2018.

BACKGROUND: Japanese encephalitis (JE) occurs in fewer than 1% of JE virus (JEV) infections, often with catastrophic sequelae including death and neuropsychiatric disability. JEV transmission in Pakistan was documented in 1980s and 1990s, but recent evidence is lacking. Our objective was to investigate JEV as a cause of acute encephalitis in Pakistan. METHODS: Persons aged ≥1 month with possible JE admitted to two acute care hospitals in Karachi, Pakistan from April 2015 to January 2018 were enrolled. Cerebrospinal fluid (CSF) or serum samples were tested for JEV immunoglobulin M (IgM) using the InBios JE DetectTM assay. Positive or equivocal samples had confirmatory testing using plaque reduction neutralization tests. RESULTS: Among 227 patients, testing was performed on CSF in 174 (77%) and on serum in 53 (23%) patients. Six of eight patient samples positive or equivocal for JEV IgM had sufficient volume for confirmatory testing. One patient had evidence of recent West Nile virus (WNV) neurologic infection based on CSF testing. One patient each had recent dengue virus (DENV) infection and WNV infection based on serum results. Recent flavivirus infections were identified in two persons, one each based on CSF and serum results. Specific flaviviruses could not be identified due to serologic cross-reactivity. For the sixth person, JEV neutralizing antibodies were confirmed in CSF but there was insufficient volume for further testing. CONCLUSIONS: Hospital-based JE surveillance in Karachi, Pakistan could not confirm or exclude local JEV transmission. Nonetheless, Pakistan remains at risk for JE due to presence of the mosquito vector, amplifying hosts, and rice irrigation. Laboratory surveillance for JE should continue among persons with acute encephalitis. However, in view of serological cross-reactivity, confirmatory testing of JE IgM positive samples at a reference laboratory is essential.

Population-based surveillance for severe rotavirus gastroenteritis in children in Karachi, Pakistan.

The incidence of rotavirus-associated severe diarrhoea and distribution of rotavirus genotypes in children less than five years of age was determined in two low-income communities in Karachi, Pakistan. Over a two-year period, 717 children met eligibility criteria for severe diarrhoea and stools were obtained from 575 (80%) with 97 (17%) being rotavirus positive. Adjusted annual rates of severe rotavirus diarrhoea in children less than five years and less than one year were respectively 5.7 and 16.9 per 1000 in community A, and 8.1 and 25.4 per 1000 child years of observation in community B. An estimated 1 in 40 infants experience a severe episode of rotavirus gastroenteritis annually in Pakistan. The most common rotavirus strains were G9P[8] (15%), G1P[8] (13%) and G1[P4] (8.4%). This information will inform policy decisions about the introduction of rotavirus vaccines.