Heavy rains could also bring another severe impact even after the storm passed, aid agencies warned.
“Another deadly threat lies in the wake of Winston – the presence of Zika virus in Tonga could spread easily in a response situation,” said Carlos Calderon, Pacific humanitarian manager for Oxfam New Zealand.
Oxfam said Tropical Cyclone Winston could disrupt access to running drinking water and hygienic drainage systems or mosquito control measures such as nets, raising the risk of an increase in mosquito breeding and a fresh outbreak of the Zika virus.
Aid workers have begun removing mosquito larvae from water tanks, spraying affected areas to remove the threat of Zika, and distributing mosquito nets, with a focus on pregnant women.
Tonga declared a Zika outbreak earlier this month after five cases of the mosquito-borne illness were confirmed and another 259 suspected.
WHO declared the outbreak a global public health emergency on February 1, noting its association with two neurological disorders.
- RNZI