This post is by John Balbus, M.D., M.P.H., Chief Health Scientist at Environmental Defense.
Nearly 300 people in northeast Italy have come down with a virus formerly limited to Africa and Asia called Chikungunya Fever (CHIKV). It's not usually fatal, but it's not pleasant. Sufferers experience fever, joint pain, muscle pain, and headache. In the Makonde language, "chikungunya" means "that which bends up" – a reference to the victim's contorted posture.
Dean Menke, a policy analyst here, had the disease when he was living in East Timor: "I thought I was going to die – I wished I would die just so the pain would stop. If it wasn’t for the hallucinations from the 104° fever, the whole ordeal would have been a waste."
CHIKV virus is very rare in Europe, and until now, it was only seen in travelers returning from areas with epidemics. According to a report [PDF] from the European Center for Disease Prevention and Control, this is the first time CHIKV virus has spread through local means within the European mainland. And that's why climate change must be considered.
People arrive in temperate places from tropical places all the time with viruses and parasites in their blood. But it doesn't usually lead to an outbreak in the cooler location because the means of transmission doesn't usually exist in the cooler location.
For an outbreak to occur locally, a mosquito that is able to transmit the particular virus has to bite an infected person, the virus must replicate in the mosquito's body up to an infectious dose, and then the mosquito must survive long enough to bite another person. Biting frequency, virus replication and mosquito survival all are affected by temperature and humidity.
Mosquitoes love warm weather. Other factors also play important roles, but higher temperatures from global warming could make it much more likely that this chain of events will occur quickly enough to cause outbreaks. More alarmingly, with warmer winters infected mosquitoes may survive until spring, allowing the infectious cycle to resume.
Mosquitoes transmit more than just CHIKV virus. They also spread more serious diseases such as malaria and dengue fever. In a previous article I wrote about how dengue fever is spreading from Mexico into Texas, with similar concerns about the role of climate change. And mosquitoes aren't the only heat-loving creatures that spread disease.
Climate change can impact public health in a multitude of ways, and we're already starting to see some of the harmful effects. The world can't wait – we must cap global warming gas emissions now.