NEW YORK/BOGOTA • Climate change may have fuelled the outbreak of the mosquito-borne Zika virus in Latin America and made it harder for developing countries to manage future epidemics, researchers said.
Record-high temperatures last year in Brazil, Ecuador and other South American countries created ideal conditions for the mosquito that transmits the Zika virus, which is suspected of causing birth defects, scientists said in a conference call with reporters on Friday.
The researchers, who cautioned that any link between the Zika virus and global warming remains unproven, said violent storms, floods and drought are prone to fostering the outbreak and spread of diseases, particularly in underdeveloped nations.
Extreme weather can also hobble overtaxed public health systems.
"Unless mitigated, climate change is likely to bring the spread of new emergent infectious diseases like Zika virus," said Mr Nick Watts, who leads a commission on health and climate change for the medical journal The Lancet, during the call.
Rising temperatures and increased rainfall can extend the geographic range and enrich breeding areas of mosquitoes, ticks, fleas and other insects that transmit diseases, scientists said.
The pathogens they carry tend to become more resilient at higher temperatures and go through their life cycles faster. Global warming "is posing risks for the transmission of vector-borne and other diseases", said Dr Diarmid Campbell-Lendrum, the World Health Organisation's climate change and health team leader.
The Zika epidemic parallels the 1999 West Nile Virus outbreak in New York, according to Dr Jonathan Patz, director of the Global Health Institute at the University of Wisconsin-Madison.
Both arrived during record-hot summers and involved the Aedes aegypti mosquito, which bites more frequently in hot weather.
Meanwhile, in Colombia which is seeing a sharp increase in a rare neurological disorder linked to the Zika virus, President Juan Manuel Santos said on Saturday that 25,645 people, among them 3,177 pregnant women, have been infected with the virus.
Brazil is investigating the potential link between Zika infections and more than 4,000 suspected cases of microcephaly, a birth defect marked by an abnormally small head size that can result in developmental problems.
Researchers have identified evidence of Zika infection in 17 of these cases, either in the baby or in the mother, but have not confirmed that the virus can cause microcephaly.
There are so far no recorded cases of Zika-linked microcephaly in Colombia, Mr Santos said.
The government is now uncertain about a previous projection for up to 500 cases of Zika-linked microcephaly, based on data from other countries battling the disease.
"The projection is that we could end up having 600,000 cases," Mr Santos said, adding there could be up to 1,000 cases of Guillain-Barre syndrome, a rare neurological disorder that can weaken the muscles and cause paralysis.
Scientists are studying a possible link between the disorder and the Zika virus. Much remains unknown about the virus, for which there is no vaccine. An estimated 80 per cent of those infected show no symptoms. Those who do, have a mild illness, with a fever, rash and red eyes.