LONDON: Climate change is favouring pests and parasites and triggering widespread outbreaks of disease in wildlife, according to US scientists.

Warmer summers and milder winters are encouraging disease-bearing infections that blight coral reefs, kill shellfish colonies, and threaten lions, cranes, vultures and even ferrets. Global warming is also helping to spread tropical diseases to human habitations previously unaffected by such illnesses, they reported in the journal Science on Friday.

“This is not just a question of coral bleaching for a few marine ecologists, nor just a question of malaria for a few health officials,” said Richard Ostfield, of the Institute for Ecosystem Studies, in Millbrook, New York.

Frosts and cool periods can cut insect, parasite and fungus pest populations by up to 99 per cent. But mellow winters, followed by long spells of warmth and humidity, provide perfect conditions for their survival.

Ecologists and health officials began predicting years ago that mosquitoes, ticks, rodents, viruses, fungi and bacteria were likely to spread into other areas as temperatures rose, with potentially devastating effects on wildlife.

In Hawaii, avian malaria has already wiped out native song birds living below an altitude of 1,400 metres; 30 years ago, the malarial mosquitoes only survived up to an altitude of 800 metres.

The team, led by Drew Harvell, of the ecology and evolutionary biology department at Cornell University, also used the hotspots of El Nino — the dramatic cyclic increase in the warmth of the tropical Pacific ocean that also affects African and American climate patterns — as a guide to climate trends.

The scientists looked at the massive die-off of coral during the unusually warm El Nino year of 1998. Much of the coral had died from fungal and other diseases thriving in warmer seas.

Oysters in the US state of Maine, had been blighted by parasites normally restricted to more southerly waters. Lions in the Serengeti had suffered canine distemper, and cranes, vultures and even wild American ferrets had been hit by disease outbreaks. The monarch butterfly came under pressure from an exploding parasite population.

Rift valley fever, a devastating viral illness of cattle and humans, spread by mosquitoes, also spread during the hot El Nino year of 1998.

In a warmer world, such events could occur more regularly: viruses in the mosquito population would multiply, and so too would the mosquitoes.—Dawn/The Guardian News Service.