Assessment of Food and Waterborne Viral Outbreaks by Using Field Epidemiologic, Modern Laboratory and Statistical Methods-Lessons Learnt from Seven Major Norovirus Outbreaks in Finland.

Seven major food- and waterborne norovirus outbreaks in Western Finland during 2014-2018 were re-analysed. The aim was to assess the effectiveness of outbreak investigation tools and evaluate the Kaplan criteria. We summarised epidemiological and microbiological findings from seven outbreaks. To evaluate the Kaplan criteria, a one-stage meta-analysis of data from seven cohort studies was performed. The case was defined as a person attending an implicated function with diarrhoea, vomiting or two other symptoms. Altogether, 22% (386/1794) of persons met the case definition. Overall adjusted, 73% of norovirus patients were vomiting, the mean incubation period was 44 h (4 h to 4 days) and the median duration of illness was 46 h. As vomiting was a more common symptom in children (96%, 143/149) and diarrhoea among the elderly (92%, 24/26), symptom and age presentation should drive hypothesis formulation. The Kaplan criteria were useful in initial outbreak assessments prior to faecal results. Rapid food control inspections enabled evidence-based, public-health-driven risk assessments. This led to probability-based vehicle identification and aided in resolving the outbreak event mechanism rather than implementing potentially ineffective, large-scale public health actions such as the withdrawal of extensive food lots. Asymptomatic food handlers should be ideally withdrawn from high-risk work for five days instead of the current two days. Food and environmental samples often remain negative with norovirus, highlighting the importance of research collaborations. Electronic questionnaire and open-source novel statistical programmes provided time and resource savings. The public health approach proved useful within the environmental health area with shoe leather field epidemiology, combined with statistical analysis and mathematical reasoning.

Long-term population effects of infant 10-valent pneumococcal conjugate vaccination on pneumococcal meningitis in Finland.

BACKGROUND: No previous studies have reported long-term follow-up of ten-valent pneumococcal conjugate vaccine (PCV10) program impact on pneumococcal meningitis (PM). We assessed the effects of infant PCV10 program on PM incidence, mortality and serotype distribution in children and adults during 7 years after introduction. METHODS: We conducted a population-based observational study. A case of PM was defined as isolation of Streptococcus pneumoniae from cerebrospinal fluid or, a patient with S. pneumoniae isolated from blood and an ICD-10 hospital discharge diagnosis of bacterial meningitis within 30 days before or after positive culture date.We compared age- and serotype-specific incidence and associated 30-day mortality rates in 2011-2017 (PCV10 period) with those in 2004-2010 (pre-PCV10 baseline) by using Poisson regression models. Absolute rate differences and 95% confidence intervals (CIs) were calculated from the parameter estimates by using delta method. RESULTS: During the PCV10 period, the overall incidence of PCV10 serotype meningitis decreased by 68% (95%CI 57%-77%), and the overall PM incidence by 27% (95%CI: 12%-39%). In age groups 0-4, 50-64, and ≥ 18 years, the overall PM incidence was reduced by 64%, 34% and 19%, respectively. In adults ≥ 65 years of age, a 69% reduction in PCV10 serotypes was offset by 157% (56%-342%) increase in non-PCV10 serotypes. The overall PM-related mortality rate decreased by 42% (95%CI 4%-65%). Overall case fatality proportion (CFP) was 16% in pre-PCV10 period and 12% in PCV10 period (p = 0.41); among persons 50-64 years the CFP decreased from 25% to 10% (p = 0.04). CONCLUSIONS: We observed substantial impact and herd protection for vaccine-serotype PM and associated mortality after infant PCV10 introduction. However, in older adults ≥ 65 years of age, PM burden remains unchanged due to serotype replacement.

Pneumococcal meningitis before the introduction of 10-valent pneumococcal conjugate vaccine into the National Childhood Immunization Program in Poland.

BACKGROUND: Poland introduced the 10-valent conjugate pneumococcal vaccine (PCV10) into the childhood immunization program in January 2017. During previous decades, considerable changes had occurred in the surveillance system for invasive pneumococcal disease. Therefore, to provide baseline data on pneumococcal diseases before PCV10 introduction, we evaluated the epidemiology of pneumococcal meningitis (PM), the only syndrome monitored consistently since 1970. METHODS: Based on laboratory-confirmed cases reported during 2005-2015, we calculated the reported rates, serotypes distribution and antimicrobial resistance of pneumococcal meningitis isolates. Data from the mandatory national surveillance system was linked with data on cerebrospinal fluid isolates submitted to the National Reference Centre for Bacterial Meningitis. We used negative binomial regression with Newey West method to test for trend in rates of pneumococcal meningitis notified during 2005-2015 and Chi-squared test to assess changes in the serotype distribution from 2008-2011 to 2012-2015. RESULTS: From 2005 to 2015, the overall reported incidence of PM increased from 0.21 to 0.47 cases per 100,000 population, average yearly increase of 7% (rate ratio 1.07; 95% CI 1.06-1.08). The increase was primarily due to annual increase of 3% (1.02-1.05) among 15-49 years of age, 12% (95% CI: 1.10-1.13) among 50-64 years of age, 18% (95% CI: 1.16-1.19) among persons 65-74 years of age and 9% (95% CI 1.07-1.10) among persons ≥75 years of age. In children <5 years of age, serotypes included in PCV10 and PCV13 accounted for 75% and 80% of reported isolates, respectively. From 2008-2011 to 2012-2015, the proportion of PM cases caused by PCV10 serotypes decreased from 52% to 41% (p < 0.01). Overall, 28% of isolates were resistant to penicillin and 13% were non-susceptible to cefotaxime. CONCLUSIONS: The introduction of PCV10 into national immunization program may have considerable impact on disease burden, especially on number of cases caused by isolates non-susceptible to antimicrobials.

Bacterial meningitis in Finland, 1995-2014: a population-based observational study.

OBJECTIVES: Bacterial meningitis remains an important cause of morbidity and mortality worldwide. Its epidemiological characteristics, however, are changing due to new vaccines and secular trends. Conjugate vaccines against Haemophilus influenzae type b and Streptococcus pneumoniae (10-valent) were introduced in 1986 and 2010 in Finland. We assessed the disease burden and long-term trends of five common causes of bacterial meningitis in a population-based observational study. METHODS: A case was defined as isolation of S. pneumoniae, Neisseria meningitidis, Streptococcus agalactiae, Listeria monocytogenes or H. influenzae from cerebrospinal fluid and reported to national, population-based laboratory surveillance system during 1995-2014. We evaluated changes in incidence rates (Poisson or negative binomial regression), case fatality proportions (χ2) and age distribution of cases (Wilcoxon rank-sum). RESULTS: During 1995-2014, S. pneumoniae and N. meningitidis accounted for 78% of the total 1361 reported bacterial meningitis cases. H. influenzae accounted for 4% of cases (92% of isolates were non-type b). During the study period, the overall rate of bacterial meningitis per 1 00 000 person-years decreased from 1.88 cases in 1995 to 0.70 cases in 2014 (4% annual decline (95% CI 3% to 5%). This was primarily due to a 9% annual reduction in rates of N. meningitidis (95% CI 7% to 10%) and 2% decrease in S. pneumoniae (95% CI 1% to 4%). The median age of cases increased from 31 years in 1995-2004 to 43 years in 2005-2014 (p=0.0004). Overall case fatality proportion (10%) did not change from 2004 to 2009 to 2010-2014. CONCLUSIONS: Substantial decreases in bacterial meningitis were associated with infant conjugate vaccination against pneumococcal meningitis and secular trend in meningococcal meningitis in the absence of vaccination programme. Ongoing epidemiological surveillance is needed to identify trends, evaluate serotype distribution, assess vaccine impact and develop future vaccination strategies.

Rubella in Poland in 2014

BACKGROUND: In 2004, Poland has adopted the WHO goal of rubella elimination and congenital rubella syndrome prevention. The main target of the Programme is to stop transmission of the virus in the environment and prevention of congenital rubella in children. In Poland participation in the rubella elimination program requires clinical diagnosis of rubella cases and their confirmation with laboratory tests. Vaccination against rubella was introduced in 1987, initially only in 13 - year-old girls. Since 2003, single jab vaccination against rubella, measles and mumps is used (MMR vaccine for all children: primary vaccination at the age 13-15 months and a booster vaccination at the age of 10). AIM: To assess epidemiological situation of rubella in Poland in 2014, including vaccination coverage in Polish population. MATHERIAL AND METHODS: The descriptive analysis was based on data retrieved from routine mandatory surveillance system and published in the annual bulletins "Infectious diseases and poisonings in Poland in 2014" and "Vaccinations in Poland in 2014" (MP. Czarkowski, Warszawa 2014, NIZP-PZH, GIS). RESULTS: In 2014, there was a significant decrease in the number of rubella cases - with registered 5891 cases (in 2013 - 38 548 cases) - and a decline in incidence (from 101.1 per 100 000 to 15.3). The highest incidence, regardless of gender and the environment was observed in the age group 5-6 years (respectively 93.8 and 109.4 per 100 000). Similarly to 2013, rubella incidence of males was higher than the incidence in girls and women (20.0 versus 10.9). In 2014, no cases of congenital rubella syndrome were registered. SUMMARY AND CONCLUSIONS: The proportion of laboratory tests confirming/excluding rubella infection is still very low in Poland. In 2014, only 0.6% of rubella cases were laboratory confirmed.

An Outbreak of Norovirus Infections Among Lunch Customers at a Restaurant, Tampere, Finland, 2015.

On January 29, 2015, the city of Tampere environmental health officers were informed of a possible foodborne outbreak among customers who had eaten lunch in restaurant X. Employees of electric companies A and B had a sudden onset of gastrointestinal symptoms. We conducted a retrospective cohort study to identify the vehicle, source, and causative agent of the outbreak. A case was defined as an employee of companies A or B with diarrhea and/or vomiting who ate lunch at Restaurant X on January 26, 2015. All employees of the companies attending the implicated lunch were invited to participate in the cohort study. Environmental investigation was conducted. Twenty-one responders were included in statistical analysis, of which 11 met with the case definition. Of the 15 food items consumed by participants, four food items were associated with gastroenteritis. Of four kitchen staff, three tested positive for norovirus GIP7, the strain was found earlier in the community. No patient samples were obtained. Level of hygiene in the kitchen was inadequate. Infected kitchen staff probably transmitted norovirus by inadequate hygiene practices. No new cases associated with Restaurant X were reported after the hygiene practices were improved.

[Meningitis and encephalitis in Poland in 2010]. / Zapalenia opon mózgowo--rdzeniowych i zapalenia mózgu w Polsce w 2010 roku.

INTRODUCTION: Annually 2 000-3 000 cases of meningitis and encephalitis are notified to the Polish surveillance system. The leading etiologic agents of the bacterial infections are: N. meningitidis, S. pneumoniae, H. influenzae type B and L. monocytogenes. The most common causes of bacterial infections in children are: E. coli, S. agalactiae and H. influenzae type B. The viral infections are mainly caused by the following pathogens: Echovirus, Coxsackie virus group A and B. The agents responsible for the viral infections are also: arboviruses, Herpes simplex virus and mumps virus. OBJECTIVES: The objectives of the present article are to analyze the epidemiology of meningitis and encephalitis in Poland in 2010 and to present the information on the vaccines used to prevent the discussed infections. MATERIAL AND METHODS: The analysis was based on the data retrieved from the questionnaires used for the surveillance purposes, aggregated data on meningitis and encephalitis published in "Infectious diseases and poisonings in Poland in 2010", aggregated data on the vaccination coverage published in "Vaccinations in Poland in 2010", "Case definitions for the infectious diseases used for the surveillance purposes in 2009-2011" and Polish Immunization Programme for 2010. RESULTS: In 2010, Poland reported 3 063 neuroinfections--nearly 22% more than in 2009. The incidence rate was 8.03 cases per 100 000 population. From the analysis of data transpired that of the notified cases, 1 619 were of viral etiology, 846--were bacterial and 598 of other or unknown origin. Given the bacterial infections of determined etiology, the leading pathogenic agent was S. pneumoniae (180 cases), following by N. meningitidis (146 cases) and Haemophilus influenzae typu B (11 cases). Among confirmed cases of the viral infections, the predominant were tick-borne encephalitis cases (294). CONCLUSIONS: Compared to the data from 2009, the epidemiologic situation of the meningitis and encephalitis in Poland in 2010 has not changed significantly.

[Meningitis and encephalitis in Poland in 2009]. / Zapalenia opon mózgowo-rdzeniowych i zapalenia mózgu w Polsce w 2009 roku.

In Poland, 2 517 cases of neuroinfections were reported in 2009, of which 865 had bacterial aetiology, 1 244--viral aetiology, and 408-- other or unknown origin. The etiological agent was determined in 493 (57%) cases of bacterial neuroinfections. Among them Neisseria meningitidis was found in 190 cases, Haemophilus influenzae type B (Hib) in 13 cases and Streptococcus pneumoniae in 163 cases. An increasing trend in pneumococcal infections incidence has been observed since 2005, and a substantial decrease of Hib incidence, related to increasing vaccination coverage. Viral neuroinfections incidence in 2009 increased compared to year 2008. Among confirmed cases, there were 351 cases of tick-borne encephalitis. Most of the cases were reported from endemic areas of north-eastern part of the country.

Reliable surveillance of tick-borne encephalitis in European countries is necessary to improve the quality of vaccine recommendations.

In July-November 2009, 26 European Union (EU) Member States (MSs), Norway and Iceland, participated in a survey seeking information on national tick-borne encephalitis (TBE) vaccination recommendations. Information on TBE surveillance, methods used to ascertain endemic areas, vaccination recommendations, vaccine coverage and methods of monitoring of vaccine coverage were obtained. Sixteen countries (57%) reported presence of TBE endemic areas on their territory. Vaccination against TBE was recommended for the general population in 8 (28%) countries, for occupational risk groups - in 13 (46%) countries, and for tourists going abroad - in 22 (78%) countries. Although vaccination recommendations for country residents, and for tourists always referred to endemic areas, there was no uniform, standardized method used to define endemic areas. For this reason, clear recommendations for tourists need to be developed, and standardized surveillance directed to efficient assessment of TBE risk need to be implemented in European countries.

[Meningitis and encephalitis in Poland in 2008]. / Zapalenia opon mózgowo-rdzeniowych i zapalenia mózgu w Polsce w 2008 roku.

In Poland, 2 475 cases of neuroinfections were reported in 2008, of which 979 had bacterial aetiology, 1 122--viral aetiology, and 374--other or unknown origin. The etiological agent was determined in 555 (56%) cases of bacterial neuroinfections. Among them Neisseria meningitidis was found in 220 cases, Haemophilus influenzae type B (Hib) in 23 cases and Streptococcus pneumoniae in 151 cases. An increasing trend in meningococcal infections incidence has been observed in 2008, and a substantial decrease of Hib incidence, related to increasing vaccination coverage. Viral neuroinfections incidence in 2008 decreased compared to year 2007. Among confirmed cases, there were 202 cases of tick-borne encephalitis. Most of the cases were reported from endemic areas of north-eastern part of the country.

[Meningitis and encephalitis in Poland in 2007]. / Zapalenia opon mózgowo-rdzeniowych i zapalenia mózgu w Polsce w 2007 roku.

In Poland, 3,361 cases of neuroinfections were reported in 2007, of which 1,078 had bacterial etiology, 1,717--viral aetiology, and 566--other or unknown origin. The etiological agent was determined in 611 (57%) cases of bacterial neuroinfections. Among them N. meningitidis was found in 224 cases, H. influenzae type B (Hib) in 35 cases and S. pneumoniae in 161 cases. An increasing trend in meningococcal infections incidence has been observed in 2007, and a substantial decrease ofHib incidence, related to increasing vaccination coverage. Viral neuroinfections incidence in 2007 increased compared to year 2006. Among confirmed cases, there were 233 cases oftick-borne encephalitis. Most of the cases were reported from endemic areas of north-eastern part of the country.