Detection and identification of Anaplasma phagocytophilum, Borrelia burgdorferi, and Rickettsia helvetica in Danish Ixodes ricinus ticks.

Borreliosis is an endemic infection in Denmark. Recent serosurveys have indicated that human anaplasmosis may be equally common. The aim of this study was to look for Anaplasma phagocytophilum and related pathogens in Ixodes ricinus ticks and estimate their prevalence, compared to Borrelia, using PCR. Ticks were collected from three locations in Denmark: Jutland, Funen, and Bornholm. Ticks from Jutland and Funen were analysed individually, ticks from Bornholm were analysed in pools of 20. A. phagocytophilum was found in ticks from all areas. A. phagocytophilum was found in 23.6% of ticks from Jutland and Funen, while 11% were positive for Borrelia burgdorferi. The Borrelia genotype B. afzelii was most prevalent, followed by B. valaisiana, B. burgdorferi s.s. and B. garinii.A. phagocytophilum was found in 14.5% of nymphs and 40.5% of adult ticks, while Borrelia was found in 13% of nymphs and 8% of adult ticks. The difference in prevalence between Anaplasma and Borrelia in adult ticks supports the idea that their maintenance cycles in nature may be different. Ticks were also infected with Rickettsia helvetica. Our study indicates that A. phagocytophilum prevalence in ticks in Denmark is as high as Borrelia prevalence and that human anaplasmosis may be unrecognized.

Acoustic reflections during rhinometry: spatial resolution and sound loss.

The accuracy of the acoustic reflections method for the evaluation of human nasal airway geometry is determined by the physical limitations of the technique and also by the in vivo deviations from the assumptions of the technique. The present study 1) examines the sound loss caused by nonrigidity of the nasal mucosa and viscous loss caused by complex geometry and its influence on the estimation of the acoustic area-distance function; 2) examines the optimal relation between sampling frequency and low-pass filtering, and 3) evaluates advantages of breathing He-O2 during the measurements on accuracy. Measurements made in eight plastic models, with cavities exactly identical to the "living" nasal cavities, revealed only minor effects of nonrigidity of the nasal mucosa. This was confirmed by an electrical analog model, based on laser vibrometry admittance measurements of the nasal mucosa, which indicated that the error in the acoustic measurements caused by wall motion is insignificant. The complex geometry of the nasal cavity per se (i.e., departure from circular) showed no significant effects on the measurements. Low-pass filtering of the signal is necessary to cut off cross modes arising in the nasal cavity. Computer simulations and measurements in models showed that the sampling frequency should be approximately four times the low-pass filtering frequency (i.e., twice the Nyquist frequency) to avoid influence on the result. No advantage was found for the the use of He-O2 vs. air in the nasal cavity.

Nasal airway dimensions in term neonates measured by continuous wide-band noise acoustic rhinometry.

The nasal airways of 94 healthy term infants (37-42 weeks gestational age) were examined by continuous wide-band noise acoustic rhinometry under standardized conditions on the second or third day postpartum. Validation of the flexible infant probe on tubular plastic models with dimensions similar to the nasal cavity of newborn infants showed a correlation coefficient of 0.98. The mean and standard deviation (SD) of the total minimal cross-sectional area (TMCA), the distance from the nostril to the MCA (DMCA) and the total volumes between the nostril and 45 mm into the nasal cavity (TVOL45) were 0.20 +/- 0.05 cm2, 0.76 +/- 0.29 cm and 2.14 +/- 0.39 cm3 respectively. In general, both anthropometric and rhinometric mean values were higher in males (n = 52) compared to females (n = 42), and the difference was statistically significant for TMCA and head circumference. We conclude that the technical properties, small size and flexible tube of the miniprobe make it uniquely suited for objective assessment of the nasal airways in infants and small children. The RHIN 2000/2100 miniprobe (S.R. Electronics Aps, Lynge, Denmark) is the first infant probe commercially available, making standardization and comparison of results easier.

Changes in nasal airway dimensions in infancy.

Thirty-nine infants, previously examined as neonates, were re-examined at 1 year of age with continuous wide-band noise acoustic rhinometry using a specific probe optimized for infants, to determine the dimensional growth and maturation of nasal airway geometry in otherwise healthy infants. During the first year of life, the acoustically determined dimensions of the nasal airways increased significantly. The total minimal cross-sectional area increased by 67% (0.21 cm2-->0.35 cm2), the volume of the anterior 4 cm of the nasal airway by 36% (1.80 cm3-->2.44 cm3) and the distance to the minimum cross-sectional area by 19% (0.78 cm-->0.93 cm). The rhinometric values of male infants were significantly larger than those of females. However, after adjusting for the significantly larger anthropometric values of males, the difference disappeared, indicating that it was mainly due to body size and not directly to gender. A highly significant correlation (r=0.44, p < 0.006) was observed between the minimum cross-sectional area and head circumference, which anatomically are the most closely related rhinometric and anthropometric values. Furthermore, when differentiating between infants with or without signs of nasal congestion during the fortnight preceding the rhinometric evaluation, a reduction in the total volume of the anterior 4 cm (17% p <0.02) and minimum cross-sectional area (12%, ns) was observed after adjustment. We conclude that the optimized acoustic rhinometric probe is a useful investigative modality, permitting studies of upper airway physiology of healthy and diseased infants.

Technical abilities and limitations of acoustic rhinometry optimised for infants.

The objective of this model study was to validate in detail the technical capabilities as well as the limitations of a new rhinometric probe optimised for infants in order to improve reliability of measurements and reduce the risk of misleading conclusions. The repeatability was excellent (CV < 0.6%) and the reproducibility was high (CV% < 4%) provided the ambient conditions were fairly stable. The repeatability declined when external noise levels were above 60 dB SPL, and variation in temperature and pressure reduce reproducibility. The accuracy of the minimum cross-sectional area (MCA) as well as the volume corresponding to the nasal cavity in infants (VOL4), was acceptable (% error < 12%) as long as the MCA was larger than 30-40% of the probe dimensions and the cross-sectional area of the cavity posterior to the MCA did not exceed the MCA by a factor of more than 3-4. Variation in the position of the MCA within the anterior 2 cm has minimal influence on the posterior measurements provided the shape and length of the MCA are unaltered. Rods inserted into the tubular model to simulate the slit-like shape of the nasal passage did not reduce the accuracy, which is essential to the clinical value of acoustic rhinometry. Recommendations and guidelines designed to enhance the reliability of acoustic measurements in infants are presented.