Health

AUSTRALIA is experiencing the biggest outbreak of the highly virulent Hendra virus since the disease was identified in 1994. Worse, a change in the symptoms in horses suggests that new strains may have emerged. The big worry is that a strain capable of spreading from human-to-human will follow.

Hendra virus originated in fruit bats but passed to horses and then people, where it tends to affect the nervous system, causing headaches, convulsions and coma. It can be fatal. As New Scientist went to press, the latest outbreak had infected two people, who remain in hospital, while 50 more are being tested.

Classic horse symptoms are laboured breathing, frothy nasal discharge, a swollen muzzle and death within days. This time, however, horses have mainly suffered neurological symptoms such as paralysis and loss of balance. This, along with "very preliminary sequencing data", suggests that "there is a cluster of strains that differ in their pathogenesis and infectivity", says Hume Field of the Australian Biosecurity Cooperative Research Centre for Emerging Infectious Disease. Such a cluster makes it more likely that a strain that can pass between humans will arise.

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