A team of Australian researchers has discovered a possible link between the El Niño Southern Oscillation Index (SOI) and the occurrence of hepatitis A in Australia.

In a letter published in the latest edition of the Medical Journal of Australia, Wenbiao Hu, Anthony McMichael and Shilu Tong report results that indicate that the El Niño SOI is statistically significantly associated with the transmission of hepatitis A.

The researchers established the link by studying data on the monthly counts of hepatitis A cases in Australia and the monthly SOI between January 1991 and December 2000.

A decrease in the SOI was associated with a statistically significant increase in the monthly incidence of hepatitis, and the El Niño events of 1991-92 and 1997-98 were clearly associated with an increased incidence of hepatitis A.

The results suggested an increase of about 360 cases per year for, on average, an inter-quartile range decrease in the SOI.

The El Niño Southern Oscillation (ENSO) has been related to waterborne disease, vector-borne disease, and natural disaster-related deaths from floods and bushfires and cyclones.

This latest Australian research adds further evidence of ENSO-related health effects.

Infectious diseases are, in general, sensitive to climate variability, as climate can influence the development and transmissibility of pathogens, and can also affect people's behaviour.

If the El Niño link to hepatitis A is confirmed by other studies, the researchers predict the need for early warning systems to assist in disease prevention and control.

The Medical Journal of Australia is a publication of the Australian Medical Association.

CONTACT:     Dr Shilu TONG,  (07) 3864 9745,  s.tong@qut.edu.au

                   Judith TOKLEY, AMA Public Affairs,  02 6270 5471 (w)  0408 824 306