The Poughkeepsie Journal just reported a study published in PLOS one explaining why small mammals spread not only Lyme disease, but other tick-borne co-infections. "This study suggests that because the small critters tend to congregate in large numbers, the pathogens that cause Lyme disease, babesiosis and anaplasmosis have more opportunities to adapt to their hosts. This creates a compounding effect whereby animals that don't effectively fight off the disease also provide more opportunities for the diseases to adapt to their meager defenses". Patients with Lyme-MSIDS often suffer from chronic borreliosis as well as other tick-borne co-infections like Babesiosis, and once these co-infections are properly diagnosed and treated, many patients with persistent symptoms improve.
http://www.poughkeepsiejournal.com/story/news/health/lyme-disease/2014/09/22/lyme-disease-mice-study/16076671/
http://www.poughkeepsiejournal.com/story/news/health/lyme-disease/2014/09/22/lyme-disease-mice-study/16076671/
Short lifespans and high densities create compounding effect that increases risk of diseases.
POUGHKEEPSIEJOURNAL.COM