Babesiosa-Lyme disease co-infection
Tick-borne diseases are increasingly becoming an important public health issue as is evidenced by the current national epidemic of Lyme disease and the increasing prevalence of human babesiosis, a more serious malaria-like illness caused by the same tick vector. The emergence of these diseases in recent decades is due the rapid expansion in the range of the vector tick, Ixodes scapularis, but the expansion of the agent of human babesiosis (Babesia microti) has been much slower than that of the agent of Lyme disease (Borrelia burgdorferi).
This project explored the interactions between these pathogens in a series of laboratory experiments involving a natural reservoir host (Peromyscus leucopus mice). What was found was that coinfection with B. burgdorferi enhances the transmission of B. microti from reservoir host to the Ixodes scapularis tick vector.
The finding suggests that the geographic expansion of human babesiosis may be dependent upon the presence of B. burgdorferi and that this disease will continue to emerge throughout the eastern US wherever Lyme disease is epidemic.
Babesiosis emergence in the United States
Human Borrelia miyamotoi Infection in the United States
Borrelia miyamotoi, a spirochete that is genetically related to the species of borrelia that cause relapsing fever, has been detected in all tick species that are vectors of Lyme disease. It was detected in Ixodes scapularis ticks from Connecticut in 2001 and subsequently has been detected in all areas of the United States where Lyme disease is endemic. The first human cases of B. miyamotoi infection were reported in Russia in 2011. We now provide evidence of B. miyamotoi infection and the prevalence of this infection among people in the United States. New England Journal of Medicine paper.
PI: Peter Krause
EcoEpidemiology of Lyme disease on Block Island, RI
The number of cases of Lyme disease and Babesiosis have increased dramatically in recent years. Current strategies to reduce the incidence of tick-borne diseases rely mostly on the use of area-wide applications of acaricides, which have been reported to be highly effective in reducing the density of infected ticks, although a recent study did not find them effective in reducing Lyme disease incidence. Less than 25% of residents of hyperendemic communities report using acaricides due to their potential toxicity to humans, pets or the environment. Personal protective measures have been found to be effective in reducing tick-borne disease incidence. Comparisons between environmental and behavioral risk factors have been hindered by the paucity of studies linking risk to disease incidence.
We are currently evaluating the relative importance of environmental and behavioral approaches for reducing the incidence of Lyme disease and Babesiosis in two contrasting ecological settings: an island and a mainland site. The project will take advantage of ongoing human cohort studies on the epidemiology of Lyme disease and Babesiosis at both sites. We shall couple these studies with assessments of ecological and behavioral risk factors in peridomestic and community setting. We will also develop an acarological risk map for Block Island, RI and Mansfield, CT that will describe spatial heterogeneity in acarological risk due to land use and landscape patterns.