1. Centre for International Health, University of Bergen, Bergen 5021, Norway
2. Child Health Department, Institute of Medicine, Tribhuvan University, Kathmandu 2533, Nepal
3. Statens Serum Institut, Department of Epidemiology, Division of Epidemiology, Copenhagen 2300, Denmark
4. Norwegian Institute of Public Health, Oslo 0403, Norway
5. Medical Microbiology, Department of Laboratory Medicine, Sykehuset Innlandet Lillehammer 2629, Norway