1 Department of Immunogenetics, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan.
2 Department of Microbiology, University of Chicago, Chicago, IL, USA.
3 Epidemiology and Disease Control Division, Department of Health Services, Ministry of Health and Population, Kathmandu, Nepal.
4 Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK. Electronic address: oliver.brady@lshtm.ac.uk.