[Survey of the infestation level of the Ixodes ricinus tick by Borrelia burgdorferi. Complimentary report].

In a recent report, we gave results of a 4 year consecutively survey (1987 to 1990) of the level of Ixodes ricinus nymphs infested by Borrelia burgdorferi in two forests of the western part of France. This brought us to conclude that there was a relative stability for this level in course of time. Results of this survey kept on in 1991 oblige us to partly modify our conclusion, on account of an important dropping of the tick infection frequency in one of the two forests, this perhaps in connection with a large observed decreasing of the micromammals populations (but not of ticks ones) due probably to an exceptional drought during all the 1990 year.