The value of seroprevalence data as surveillance tool for Lyme borreliosis in the general population: the experience of Belgium.

BACKGROUND: Serological surveillance, based on the measurement of the presence of specific antibodies in a given population, can be used in addition to traditional and routine disease surveillance methods. The added value of this has been largely documented for vaccine-preventable diseases, but to a lesser extent for vector-borne diseases. This study aimed to evaluate the utility of seroprevalence data as additional source of information on the epidemiology of Lyme borreliosis in Belgium. METHODS: In total, 3215 residual blood samples collected in 2013-2015 were analysed with Liaison® Borrelia IgG kit (DiaSorin S.p.A, Saluggia, Italy). Positive and equivocal results were further examined with immunoblotting (recomLine Borrelia IgG kit, Mikrogen, Neuried, Germany). Crude prevalence estimates of equivocal and seropositive results were calculated and further adjusted accounting for clustered sampling and standardized for age, sex and population per province, according to the Belgian population structure in 2014. The effect of age, sex and region on seropositivity was assessed using log-binomial regression. RESULTS: The overall weighted national seroprevalence for Borrelia burgdorferi sensu lato, adjusted for clustered sampling, age, sex and province was 1.06% (95%CI 0.67-1.67). Although not statistically significant, the highest prevalences were observed in men and in those younger than 15 years or older than 59 years of age. At provincial level, the seroprevalence estimates do not follow the geographical distribution of tick bites and diagnoses of Lyme borreliosis as detected through other surveillance systems. CONCLUSIONS: Although the use of residual samples for seroprevalence estimates has several advantages, it seems to be a limited tool for serological surveillance of Lyme borreliosis in Belgium, other than follow-up of trends if repeated over time. A population-based sampling strategy might provide a more representative nationwide sample, but would be very time intensive and expensive. Seroprevalence studies within risk groups or risk areas in Belgium could provide a useful alternative approach to complement routine surveillance data of Lyme borreliosis.

Strong increase of true and false positive mycobacterial cultures sent to the National Reference Centre in Belgium, 2007 to 2016.

IntroductionIn 2007, a new federal legislation in Belgium prohibited non-biosafety level 3 laboratories to process culture tubes suspected of containing mycobacteria.AimTo present mycobacterial surveillance/diagnosis data from the Belgian National Reference Centre for mycobacteria (NRC) from 2007 to 2016.MethodsThis retrospective observational study investigated the numbers of analyses at the NRC and false positive cultures (interpreted as containing mycobacteria at referring clinical laboratories, but with no mycobacterial DNA detected by PCR in the NRC). We reviewed mycobacterial species identified and assessed trends over time of proportions of nontuberculous mycobacteria (NTM) vs Mycobacterium tuberculosis complex (MTBc), and false positive cultures vs NTM.ResultsFrom 2007 to 2016, analyses requests to the NRC doubled from 12.6 to 25.3 per 100,000 inhabitants. A small but significant increase occurred in NTM vs MTBc proportions, from 57.9% (587/1,014) to 60.3% (867/1,437) (p < 0.001). Although NTM infection notification is not mandatory in Belgium, we annually received up to 8.6 NTM per 100,000 inhabitants. M. avium predominated (ca 20% of NTM cultures), but M. intracellulare culture numbers rose significantly, from 13.0% (74/587) of NTM cultures in 2007 to 21.0% (178/867) in 2016 (RR: 1.05; 95% CI: 1.03-1.07). The number of false positive cultures also increased, reaching 43.3% (1,097/2,534) of all samples in 2016.ConclusionWe recommend inclusion of NTM in sentinel programmes. The large increase of false positive cultures is hypothesised to result from processing issues prior to arrival at the NRC, highlighting the importance of sample decontamination/transport and equipment calibration in peripheral laboratories.

Studies needed to address public health challenges of the 2009 H1N1 influenza pandemic: insights from modeling.

In light of the 2009 influenza pandemic and potential future pandemics, Maria Van Kerkhove and colleagues anticipate six public health challenges and the data needed to support sound public health decision making.

A meta-analysis on the effects of antibiotic treatment on duration of symptoms caused by infection with Campylobacter species.

Eleven randomized, controlled trials of antibiotic treatment versus placebo in patients with Campylobacter species infection were pooled in a meta-analysis. Antibiotic treatment shortened the duration of intestinal symptoms by 1.32 days (95% confidence interval, 0.64-1.99; P<.0001). Because of problems with drug resistance, a restrictive attitude towards the administration of antibiotics in uncomplicated cases is advised.

Different transmission patterns in the early stages of the influenza A(H1N1)v pandemic: a comparative analysis of 12 European countries.

Following the emergence of a novel strain of influenza A(H1N1) in Mexico and the United States in April 2009, its epidemiology in Europe during the summer was limited to sporadic and localised outbreaks. Only the United Kingdom experienced widespread transmission declining with school holidays in late July. Using statistical modelling where applicable we explored the following causes that could explain this surprising difference in transmission dynamics: extinction by chance, differences in the susceptibility profile, age distribution of the imported cases, differences in contact patterns, mitigation strategies, school holidays and weather patterns. No single factor was able to explain the differences sufficiently. Hence an additive mixed model was used to model the country-specific weekly estimates of the effective reproductive number using the extinction probability, school holidays and weather patterns as explanatory variables. The average extinction probability, its trend and the trend in absolute humidity were found to be significantly negatively correlated with the effective reproduction number - although they could only explain about 3% of the variability in the model. By comparing the initial epidemiology of influenza A (H1N1) across different European countries, our analysis was able to uncover a possible role for the timing of importations (extinction probability), mixing patterns and the absolute humidity as underlying factors. However, much uncertainty remains. With better information on the role of these epidemiological factors, the control of influenza could be improved.

Some model based considerations on observing generation times for communicable diseases.

The generation time of an infectious disease is usually defined as the time from the moment one person becomes infected until that person infects another person. The concept is similar to "generation gap" in demography, with new infections replacing births in a population. Originally applied to diseases such as measles where at least the first generations are clearly discernible, the concept has recently been extended to other diseases, such as influenza, where time order of infections is usually much less apparent. By formulating the relevant statistical questions within a simple yet basic mathematical model for infection spread, it is possible to derive theoretical properties of observations in various situations e.g. in "isolation", in households, or during large outbreaks. In each case, it is shown that the sampling distribution of observations depends on a number of factors, usually not considered in the literature and that must be taken into account in order to achieve unbiased inference about the generation time distribution. Some implications of these findings for statistical inference methods in epidemic spread models are discussed.

Risk factors for developing tuberculosis in remand prisons in St. Petersburg, Russia - a case-control study.

BACKGROUND: Detainees have a substantial risk to develop tuberculosis (TB) due to a higher incidence of TB in remand prison compared to the civil community. They develop TB during incarceration not only due to poor living conditions in remand prison, but also due to some factors affecting their life before imprisonment. Prevention measures against TB spread from penitentiary institutions to society include study of factors, which contribute to TB development. Current study aims at identification of important risk factors of TB development in remand prison in St. Petersburg, Russia. METHODS: A retrospective matched case-control study was performed from May 2002 to May 2003 in two remand prisons in St. Petersburg. One hundred and fourteen prisoners (57 cases, 57 controls) were interviewed by using standardised questionnaire. Logistic regression analysis was performed to identify risk factors. RESULTS: Six factors were significantly linked to the risk of developing TB: narcotic drug use (odds ratio (OR): 2.6, 95% confidence interval (CI): 1.0-6.9), low income (OR: 3.2, CI: 1.2-8.6), high ratio of prisoners per available bed (OR: 4.0, CI: 1.1-15.0), not having own bed clothes (OR: 13.0, CI: 2.7-61.6), and little time outdoors (OR: 3.3, CI: 1.3-8.5). However, good housing before imprisonment (OR: 4.2, CI: 1.1-15.7) was a separate risk factor for TB. CONCLUSIONS: Three of the risk factors (high number of prisoners per bed, not having own bed clothes, and little time outdoors) are certainly possible to approach by improvement of conditions in remand prisons. The remaining three factors (narcotic drug use, good housing before imprisonment, and low income) provide knowledge about study population, but cannot be intervened by prison's medical staff.

The epidemiology of gonorrhea among men who have sex with men in Stockholm, Sweden, 1990-2004.

OBJECTIVES: The objectives of this study were to analyze the spread of gonorrhea in men who have sex with men (MSM) in Stockholm regarding serovars, HIV status, and site of infection and to compare the distribution of serovars among HIV-positive and HIV-negative MSM. STUDY DESIGN: Clinical and epidemiologic data were collected for all MSM diagnosed with gonorrhea in 1990 to 2004 at a clinic primarily serving MSM. Neisseria gonorrhoeae strains were serotyped. RESULTS: A total of 1,039 isolates from 840 gonorrhea episodes in 721 patients were included. A sharp increase was seen during the 2000s. Ten percent of the cases were HIV-positive. The proportion of pharyngeal infections increased significantly (P <0.001) from 15% to 38% during the last 7 years. A great variation of serovars (n = 66) was observed, but only 5 were present >10 years. There was a significant difference (P = 0.001) in distribution of serovars correlated to HIV status. CONCLUSION: Gonorrhea is a marker for HIV infection in MSM, but the increase in gonorrhea may be associated with genital-oral sexual practice rather than with high-risk sexual practice.

Size matters -- patient organisations exaggerate prevalence numbers.

Patient organisations serve their members with information and support concerning a specific disease. In many cases they also contribute to research funding and lobby to improve the situation for their members. The larger group of patients an organisation claims to represent, the bigger their potential influence. Our hypothesis is that patient organisations exaggerate the number of persons affected with a specific disease. Prevalence figures from patient organisations in Sweden were collected via their own web sites. About 93 patient organisations were identified, 29 of which presented the estimates of disease occurrence used in this study. We calculated the probability for a person to have at least one disease and the proportion of the population not having any of the diseases listed. About 60% of the Swedish population have at least one disease covered by our sample of patient organisations. Nine tenths (87%) of the population would be ill if one assumes that an individual could only have one disease. Our rough estimates suggest that patient organisations exaggerate the number of ill persons. To render other messages on their agenda more trustworthy, we propose that some patient organisations moderate their prevalence and/or incidence figures.