Risk of exposure to ticks (Ixodidae) and the prevalence of tick-borne encephalitis virus (TBEV) in ticks in Southern Poland.

The article presents the results of the first study on seasonal activity of ticks and prevalence of tick-borne encephalitis virus (TBEV) in nymphs from the Silesian Province (Southern Poland). Previous studies on the prevalence of TBEV in ticks in Poland have been conducted mostly in northern and eastern regions, but none in the Silesian Province itself. The aims of this study were to analyse the seasonal variation in tick populations and compare TBEV prevalence in nymphs from different geographical locations in the Silesia. A total of 5160 questing Ixodes ricinus ticks were collected by the flagging method from 23 localities in southern Poland in 2010. Micro-climatic parameters (air temperature and humidity) were measured in order to estimate their influence on tick population. The highest tick activity was recorded in spring and was positively correlated with relative air humidity (RH). TBEV in the Silesian Province was analysed in 1750 nymphs and an overall prevalence was 0.11% (2 pools out of 175 analysed). The results of this study show that TBEV pool prevalence in nymphs is low in accordance with the low number of TBE cases reported within the region.

Infectious burden of respiratory syncytial virus in relation to time of birth modifies the risk of lower respiratory tract infection in infancy: the Norwegian Mother and Child Cohort.

OBJECTIVE: The risk of respiratory syncytial virus (RSV) infection according to calendar month of birth has previously been demonstrated. We hypothesize that the real-time infectious burden (IB) of RSV, in relation to time and county of birth, modifies the risk of lower respiratory tract infection (LRTI) in infants, an association that has not been investigated previously, and may be used as an alternative measure of RSV risk when drafting RSV immunoprophylaxis guidelines. METHODS: Thirty thousand eighty-seven pregnancies were included from July 1, 2003, to July 31, 2006. IB was defined by month and county as the number of RSV detections per inhabitant. IB for 5 periods ante- and postnatally was calculated for each child. Outcome variables were maternally reported hospitalization for LRTI before age 6 months and LRTI before age 12 months. Logistic regression was used to estimate associations between IB and LRTI. RESULTS: The odds of hospitalization for LRTI rise with increased IB the first 3 months after birth. Low IB: odds ratio (OR) 1.17 (95% confidence interval [CI]: 0.98-1.39); medium IB: OR 1.42 (95% CI: 1.21-1.68); high IB: OR 2.51 (95% CI: 2.15-2.94). High IB 3-0 months before birth confers a lower odds of hospitalization for LRTI the first 6 months of life, OR 0.51 (95% CI: 0.43-0.61). Similar results were seen for maternally reported LRTI the first 12 months of life. CONCLUSIONS: We find an association between real-time RSV infectious burden and LRTI in infancy: high burden before birth is protective and high burden after birth increases the risk.

Prevalence of tick borne encephalitis virus in tick nymphs in relation to climatic factors on the southern coast of Norway.

BACKGROUND: Tick-borne encephalitis (TBE) is among the most important vector borne diseases of humans in Europe and is currently identified as a major health problem in many countries. TBE endemic zones have expanded over the past two decades, as well as the number of reported cases within endemic areas. Multiple factors are ascribed for the increased incidence of TBE, including climatic change. The number of TBE cases has also increased in Norway over the past decade, and the human cases cluster along the southern coast of Norway. In Norway the distribution and prevalence of TBE virus (TBEV) in tick populations is largely unknown. The objectives of this study were to estimate the TBEV prevalence in Ixodes ricinus from seven locations and to assess the relationship between the TBEV prevalence and site-specific climatic variables. METHODS: A total of 5630 questing nymphs were collected and analyzed in pools of ten. All pools were screened with an in-house real-time RT-PCR, and the positive pools were pyrosequenced. Two methods, minimum infection rate (MIR) and a frequentist method (EPP) for pooled prevalence estimations were calculated and compared. Climatic data were descriptively compared to the corresponding EPP of each location in order to explain variations in TBEV prevalence. RESULTS: The seven foci of TBEV had an estimated overall prevalence (EPP) in pools of nymphs combined, of 0.53% with 95% CI (0.35-0.75), with point prevalence ranging between 0.11%-1.22%. The sites with the highest point prevalences were within the municipalities which had the highest numbers of registered TBE cases. The results indicate that the location with highest point prevalence had the highest relative mean humidity and lowest mean saturation deficit and vice versa for the lowest EPP. CONCLUSION: Our study confirms the existence of TBEV endemic foci in Norway. These results are of importance to increase the awareness of TBEV infections in Norway and could be used for public information and recommendations of TBE vaccination. EPP is the method of choice for pooled prevalence calculations, since it provides estimated prevalences with confidence intervals. Our findings emphasise the possible importance of microclimatic conditions regarding the TBEV prevalence in ticks.

Virus interference. Did rhinoviruses activity hamper the progress of the 2009 influenza A (H1N1) pandemic in Norway?

During summer and autumn 2009 Norway, like several other European countries, experienced an unexpected delay in the progress of the 2009 pandemic influenza A (H1N1) virus. It is considered whether interference with other respiratory viruses, in particular rhinoviruses, may have hampered the development of the influenza pandemic, and if interference phenomena are common in the development of outbreaks with epidemic viruses. If so, cytokines, in particular interferon, are the most probable executor of this effect.

Reliability of the Amplicor internal control to disclose false-negative Chlamydia trachomatis PCR results.

Four possibly false-negative samples were detected when 514 male urine specimens were tested in the Amplicor Chlamydia trachomatis assay. In three of the four samples, the inhibition could be reduced by removal of urine supernatant. Under partially inhibitory conditions, after spiking with 50 C. trachomatis elementary bodies/ml specimen, a selective inhibition of the C. trachomatis target amplification and a preferential internal control amplification was observed. We conclude that a positive internal control signal might be misleading in inhibitory specimens with low amount of C. trachomatis.

Failure to detect Chlamydia pneumoniae in aortic valves and peripheral blood mononuclear cells from patients undergoing aortic valve replacement in Norway.

The association of Chlamydia pneumoniae with atherosclerosis is still controversial. Reports from different laboratories have varied widely and "gold standards" for the detection of C. pneumoniae are lacking. In the present study, aortic valves and peripheral blood mononuclear cells from 48 patients undergoing aortic valve replacement were examined for the presence of C. pneumoniae using a nested PCR. C. pneumoniae-specific DNA was not detected in any of the clinical samples. No PCR inhibition was observed by spiking the samples with target C. pneumoniae. A total of 31/46 patients (67%) were seropositive for C. pneumoniae IgG. These results do not support the association of C. pneumoniae with aortic valves and peripheral blood mononuclear cells in patients with atherosclerotic aortic heart valve disease.