RESUMO
Ticks are vectors of several microorganisms responsible for infectious diseases in human and animals, such as Anaplasma phagocytophilum and Coxiella burnetii. In this study, we investigated the prevalence of these two bacteria in 62â889 Ixodes ricinus ticks in selected regions covering all Switzerland. A high prevalence of 11.9% of A. phagocytophilum DNA was observed by real-time PCR on 8534 pools of ticks. This pool prevalence corresponds to an estimated prevalence of 1.71% in individual tick. A total of 144 of the 171 collection sites (84.2%) were positive for the presence of A. phagocytophilum, and these sites were homogenously distributed throughout Switzerland. Such prevalence and geographical distribution underline the risk of human and animal exposure to A. phagocytophilum and highlight the need to assess the epidemiology and clinical diagnosis of human and animal anaplasmosis in Switzerland. However, DNA of C. burnetii was never found in any tick pool. This absence suggests a very low role of I. ricinus ticks as vector and reservoir of C. burnetii in Switzerland, and it supports previous reports demonstrating the role of sheep and goats in the epidemiology of Q fever. However, considering its pathogenic potential, it is necessary to keep monitoring for the possible reemergence of this bacterium in ticks in the future.
RESUMO
OBJECTIVES: The goal of the present study was to elucidate the contribution of the newly recognized virulence factor choline to the pathogenesis of Streptococcus pneumoniae in an animal model of meningitis. RESULTS: The choline containing strain D39Cho(-) and its isogenic choline-free derivative D39Cho(-)licA64--each expressing the capsule polysaccharide 2--were introduced intracisternally at an inoculum size of 10(3) CFU into 11 days old Wistar rats. During the first 8 h post infection both strains multiplied and stimulated a similar immune response that involved expression of high levels of proinflammatory cytokines, the matrix metalloproteinase 9 (MMP-9), IL-10, and the influx of white blood cells into the CSF. Virtually identical immune response was also elicited by intracisternal inoculation of 10(7) CFU equivalents of either choline-containing or choline-free cell walls. At sampling times past 8 h strain D39Cho(-) continued to replicate accompanied by an intense inflammatory response and strong granulocytic pleiocytosis. Animals infected with D39Cho(-) died within 20 h and histopathology revealed brain damage in the cerebral cortex and hippocampus. In contrast, the initial immune response generated by the choline-free strain D39Cho(-)licA64 began to decline after the first 8 h accompanied by elimination of the bacteria from the CSF in parallel with a strong WBC response peaking at 8 h after infection. All animals survived and there was no evidence for brain damage. CONCLUSION: Choline in the cell wall is essential for pneumococci to remain highly virulent and survive within the host and establish pneumococcal meningitis.