Epidemiology and Infection

A survey of Nipah virus infection among various risk groups in Singapore

K. P.  CHAN  a1 c1, P. E.  ROLLIN  a2, T. G.  KSIAZEK  a2, Y. S.  LEO  a3, K. T.  GOH  a4, N. I.  PATON  a3, E. H.  SNG  a1 and A. E.  LING  a1
a1 Virology Laboratory, Department of Pathology, Singapore General Hospital, Outram Road, Singapore 169608
a2 Special Pathogens Branch, Centers for Disease Control and Prevention, Atlanta, USA
a3 Communicable Disease Centre, Tan Tock Seng Hospital, Singapore
a4 Quarantine and Epidemiology Department, Ministry of the Environment, Singapore


Following the Nipah virus (NV) outbreak in March 1999 in Singapore, a serological survey was undertaken to screen individuals potentially exposed to NV. Blood samples were tested for NV IgM, IgG and neutralizing antibodies. Twenty-two (1·5%) of 1469 people tested had antibodies suggesting NV infection. Although 12 of the 22 infected people (54·6%) were symptomatic, the remaining 10 (45·4%) were clinically well and had no past history of compatible pulmonary or neurological disease. Clinical and serological findings suggested three people had been infected with NV before the outbreak was recognized. All those who were infected were male abattoir workers. None of the people who had contact with horses, and no healthcare workers exposed to infected patients and their specimens had detectable antibodies. This study provides evidence that NV causes asymptomatic infection. All of the antibody positive individuals had direct contact with pigs and there was no evidence of human to human transmission.

(Accepted August 5 2001)

c1 Author for correspondence.