The etiology of PD likely involves the interplay of genetic and environmental factors, but viruses have been implicated in causing parkinsonism and other movement disorders [109,110]. In a study using the cerebrospinal fluid of 67 patients (20 with PD, 29 without PD but with another neurological disorder, and 18 healthy controls), the PD patients had a significantly higher mean cerebrospinal fluid antibody response to two specific coronaviruses (MHV-JHM and MHV-A59) than controls or patients with other neurological disorders. It was theorized that some strain of coronavirus might contribute over the long term to the development of PD [110]. This may relate to the epidemiological observation that people who live on farms or grow up in farming communities have a higher risk of developing PD than others, possible due to zoonotic transmission of coronaviruses [111,112].