A study conducted by a team of Oxford University scientists and published in the open access journal PloS ONE has suggested that climate change may not be to blame for an increase in the spread of infectious diseases. The majority of research done in recent years has assumed that upsurges in diseases commonly spread by ticks and other insects, such as Lyme disease, have been due to alterations in climate regimes fostered by global warming. Dana Sumilo, the lead author on the article, and her colleagues believe this view may be erroneous.
Using Tick-Borne Encephalitis (TBE) as their model because of widely available, reliable records for infection in the Baltic region dating back to 1970, they found that cases of the disease increased significantly from 1992 to 1993 in Estonia (64%), Latvia (175%) and Lithuania (an astonishing 1065%). After comparing these records with climate records for the same period that showed an uptrend in springtime temperatures since 1989, they concluded that the warmer springs were not significantly correlated with increased TBE transmission, which would've suggested a link between global warming and higher disease transmission.
"These uniform climatic changes cannot explain how the incidence of TBE varies from district to district with infection rates peaking at different times in neighbouring districts," said Sarah Randolph, who led the study. "Our research suggests that, while changes in climate may play a role, socio-economic effects – such as those related to the break-up of the Soviet Union – have a much greater influence."
While their study only scrutinized TBE, Randolph added that the same conclusions could be applied to other infectious diseases commonly transmitted by ticks. Whether or not these results will prove applicable to other insects and the diseases they carry, such as mosquitoes and malaria, remains to be seen.