Ga. Mount et al., SIMULATION OF BLACKLEGGED TICK (ACARI, IXODIDAE) POPULATION-DYNAMICS AND TRANSMISSION OF BORRELIA-BURGDORFERI, Journal of medical entomology, 34(4), 1997, pp. 461-484
A model (LYMESIM) was developed for computer simulation of blacklegged
tick, Ixodes scapularis Say, population dynamics and transmission of
the Lyme disease agent, Borrelia burgdorferi Johnson, Schmid, Hyde, St
eigenwalt & Brenner. LYMESIM simulates the effects of ambient temperat
ure, saturation deficit, precipitation, habitat type, and host type an
d density on tick populations. Epidemiological parameters including ho
st infectivity, tick infectivity, transovarial transmission, and trans
stadial transmission are included in the model to simulate transmissio
n of the Lyme disease spirochete between vector ticks and vertebrate h
osts. Validity of LYMESIM was established by comparing simulated and o
bserved populations of immature I. scapularis on white-footed mice, Pe
romyscus leucopus, (Rafinesque), at 2 locations in Massachusetts. Vali
dity also was indicated by comparisons of simulated and observed seaso
nality of blacklegged ticks in New York, Massachusetts, Florida, and O
klahoma-Arkansas. Further model validity was shown by correlation betw
een simulated and observed numbers of immature ticks engorging on whit
e-footed mice at 3 sites in Massachusetts. The model produced acceptab
le values for initial population growth rate, generation time, and 20-
yr population density when historical meteorological data for 16 locat
ions in eastern North America were used. Realistic rates of infection
in ticks were produced for locations in the northeastern and northcent
ral United States. LYMESIM was used to study the effect of white-foote
d mouse and white-tailed deer, Odocoileus virginianus (Zimmerman), den
sities on tick density and infection rates. The model was also used to
estimate tick density thresholds for maintenance of B. burgdorferi.