Ticks can be carriers of the bacteria (Borrelia burgdorferi) that cause Lyme Disease.
Photo by James Gathany, CDC
Lyme, Connecticut
There's nothing particularly different about the town which gives its namesake to a disease carried by ticks, it just happens to be where a cluster of people with juvenile rheumatoid arthritis-like symptoms were investigated in the 1970s. It remains close to the epicenter of cases today.
Humans can influence the prevalence of Lyme Disease. The short of it is that deforestation and fragmenting ecosystems by humans can decrese populations of certain predators that feed on mice. Those predators will not hang out in areas that do not suit them, like areas with development that shrinks the size of the areas they do like to such small sizes that they no longer like those areas. When there are no predators, mice are not killed by them and the mice numbers increase. Mice have different criteria for what defines an area that suits them. Mice transmit Lyme disease to ticks easily so more mice means more Lyme disease bacteria in more ticks. Humans can be bitten by ticks in a variety of areas but the likelihood of getting bitten by an infected tick increases if there is more Lyme disease in more ticks. It plays out like this: Fragmented ecosystem = Fewer predators = More mice = More ticks with Lyme Disease = More humans with Lyme Disease.
Video about the disease-causing bacterium involved with Lyme Disease.
NPR audio about an expected rise in Lyme Disease cases (3/6/2017).