Lyme borreliosis incidence in two French departments: correlation with infection of Ixodes ricinus ticks by Borrelia burgdorferi sensu lato

• Published in: Vector borne and zoonotic diseases (Larchmont, N.Y.) Vol. 7; no. 4; p. 507
• Main Authors: Beytout, J, George, J C, Malaval, J, Garnier, M, Beytout, M, Baranton, G, Ferquel, E, Postic, D
• Format: Journal Article
• Language: English
• Published: United States 01.12.2007
• Subjects: Adolescent; Adult; Age Distribution; Aged; Anaplasma phagocytophilum - isolation & purification; Anaplasma phagocytophilum - physiology; Animals; Borrelia burgdorferi - isolation & purification; Borrelia burgdorferi - physiology; Female; France - epidemiology; Humans; Incidence; Ixodes - microbiology; Lyme Disease - epidemiology; Lyme Disease - microbiology; Male; Middle Aged; Nymph - microbiology; Population Density; Prospective Studies; Sex Distribution; France
• ISSN: 1530-3667
• DOI: 10.1089/vbz.2006.0633

We conducted a prospective study to estimate the Lyme borreliosis incidence in two rural French departments, Meuse and Puy-de-Dôme. Concurrently, we investigated the prevalence of ticks infected with Borrelia burgdorferi sensu lato (sl) and Anaplasma phagocytophilum. The incidence of Lyme borreliosis decreased from 156 to 109/100,000 inhabitants in Meuse and from 117 to 76/100,000 inhabitants in Puy-de-Dôme in 2004 and 2005, respectively, corresponding to a decrease in the density of Ixodes ricinus nymphs infected with B. burgdorferi sl. During the same period, the density of adult ticks increased. Interestingly, B. valaisiana, a nonpathogenic species, infected adult ticks more often than nymphs. These results confirmed the correlation between the Lyme borreliosis incidence and the density of infected nymphs, a stage preferentially infected with B. afzelii. In contrast, we found a low rate of infection by A. phagocytophilum, ranging from 0% to 0.4% in Puy-de-Dôme and from 0.8% to 1.4% in Meuse, suggesting a low risk for humans.