`` We show that wherever there were good conditions for gerbils and fleas in Central Asia , some years later the bacteria shows up in harbor cities in Europe and then spreads across the continent , '' Stenseth told the BBC . Rats have long been blamed for helping spread the disease in Europe . But scientists believe gerbils in Central Asia could have played a bigger role . They think the disease could have been repeatedly spread through different routes .
Rats have long been blamed for helping spread the disease in Europe . But scientists believe gerbils in Central Asia could have played a bigger role . They think the disease could have been repeatedly spread through different routes .