'Evidence for waterborne origin of an extended mixed gastroenteritis outbreak in a town in Northern Greece, 2019'.

We investigated a large gastroenteritis outbreak that occurred in Northern Greece in 2019. A case was defined as anyone presenting with diarrhoea and/or vomiting from 24 January 2019 to 04 February 2019. We conducted a case-control study (CCS) using random selection of participants >16 years of age, residents of town X, who visited the health care centre between 25 and 28 January 2019. Moreover, we conducted a retrospective cohort study (CS) at the four elementary schools of the town. We collected clinical and water samples and the water supply system was inspected. In total, we recorded 638 cases (53% female; median age was 44 years (range 0-93)). Forty-eight cases and 52 controls participated in the CCS and 236 students in the CS. Both CCS and CS indicated tap water as the most likely source (OR 10, 95% CI 2.09-93.4, explaining 95.7% of cases; RR = 2.22, 95% CI 1.42-3.46, respectively). More than one pathogen was detected from stool samples of 6 of the 11 cases tested (norovirus, Campylobacter jejuni, Enterohemorrhagic E. coli (EHEC) and Enteropathogenic E. coli (EPEC)). Water samples, collected after ad-hoc chlorination, tested negative. Technical failures of the water tanks' status were identified. Our results suggested a waterborne outbreak. We recommended regular monitoring of the water supply system and immediate repair of technical failures.

Epidemiology of hepatitis A in Greece in the last decade: management of reported cases and outbreaks and lessons learned.

Hepatitis A is a mandatory notifiable disease in Greece. Here, we present the epidemiological data for 2009-2018 and the results of outbreak investigations performed, and discuss future public health priorities.Overall, 1193 cases were reported; 320 migrants/refugees, 240 Roma, 112 travellers and 521 from the general population. The median age of the affected general population (37 years) had an increasing trend (from 30.8 years in 2009 to 40.5 in 2018, P < 0.001) and was significantly higher than that among Roma and migrants (7 and 8 years, respectively, P < 0.001). Twenty-two cases (2.2%) were unvaccinated patients with a chronic liver disease. Fifty clusters with 2-12 cases each were recorded; 44 were attributed to person-to-person transmission and six to food consumption. Three outbreaks accounting for 32.3% of the total number of recorded cases were identified; in 2013 among Roma (112 cases), in 2016 among refugees (188 cases) and in 2017 among men having sex with men (96 cases; 33 of them (34.4%) HIV-positive). The epidemiological data depict that improving living conditions and vaccination coverage of deprived populations, and informing adults on the disease focusing at faecal-oral transmission during sexual intercourse and travel should be the future public health priorities.

Excess mortality among the elderly in European countries, December 2014 to February 2015.

Since December 2014 and up to February 2015, the weekly number of excess deaths from all-causes among individuals ≥ 65 years of age in 14 European countries have been significantly higher than in the four previous winter seasons. The rise in unspecified excess mortality coincides with increased proportion of influenza detection in the European influenza surveillance schemes with a main predominance of influenza A (H3N2) viruses seen throughout Europe in the current season, though cold snaps and other respiratory infections may also have had an effect.

A large waterborne gastroenteritis outbreak in central Greece, March 2012: challenges for the investigation and management.

In March 2012, there was an unusual increase of gastroenteritis cases in a district with 37,264 inhabitants in central Greece. It was estimated that more than 3600 people developed symptoms. A 1:1 case-control study showed that consumption of tap water was a risk factor for acquiring infection [odds ratio (OR) 2.18, 95% confidence interval (CI) 1.11-4.28]. Descriptive data, low gastroenteritis incidence in adjacent areas with different water supply systems, and water-quality data further supported the hypothesis of a waterborne outbreak. Thirty-eight stool samples were positive for rotavirus. Bacterial indicators of recent faecal contamination were detected in samples from the water source and ice cubes from a local production enterprise. Molecular epidemiology of rotavirus strains, apart from the common strain, G3[P8], identified the unusual G/P combination G2P[8]. Water sanitation measures contributed to the control of the outbreak. This outbreak demonstrated the need for the cooperation of laboratories with different expertise and the importance of early notification of waterborne gastroenteritis outbreaks.

Management and investigation of viral gastroenteritis nosocomial outbreaks: lessons learned from a recent outbreak, Greece, 2012.

BACKGROUND: A nosocomial outbreak in a 740-bed hospital in Athens, Greece, was investigated in January-February 2012. METHODS: Recommendations on infection control measures were given and two case-control studies were conducted among patients (study A) and health care workers (HCWs) (study B). Compliance to control measures was evaluated. RESULTS: The absence of a routine recording system of nosocomial-acquired gastroenteritis cases led to a 10 days delay in outbreak identification. In total, 63 gastroenteritis cases were identified; 30 HCWs and 33 patients. In the multivariable analysis of study A the disease incidence among patients was statistical significantly associated with a prior incident of vomitus in their room (OR=7.96, 95% CI=1.29-49.2). In study B, the incidence was associated with the history of direct contact with a symptomatic patient (OR=3.03, 95%CI 1.01-9.12). Twenty one (75%) of the symptomatic HCWs reported absence from work for a median of 2 days (range: 1-4). Seven (25.0%) continued to work despite being symptomatic. Only, 11.1% of patients were isolated or cohorted after developing symptoms. In-hospital virological testing was not feasible and one specimen sent to a university laboratory was positive for norovirus. CONCLUSIONS: An appropriately designed protocol regarding the detection, the management and the laboratory investigation of nosocomial gastroenteritis outbreaks should be followed in order effective containment to be reassured. Hippokratia 2014; 18 (3): 204-208.

Pooling European all-cause mortality: methodology and findings for the seasons 2008/2009 to 2010/2011.

Several European countries have timely all-cause mortality monitoring. However, small changes in mortality may not give rise to signals at the national level. Pooling data across countries may overcome this, particularly if changes in mortality occur simultaneously. Additionally, pooling may increase the power of monitoring populations with small numbers of expected deaths, e.g. younger age groups or fertile women. Finally, pooled analyses may reveal patterns of diseases across Europe. We describe a pooled analysis of all-cause mortality across 16 European countries. Two approaches were explored. In the 'summarized' approach, data across countries were summarized and analysed as one overall country. In the 'stratified' approach, heterogeneities between countries were taken into account. Pooling using the 'stratified' approach was the most appropriate as it reflects variations in mortality. Excess mortality was observed in all winter seasons albeit slightly higher in 2008/09 than 2009/10 and 2010/11. In the 2008/09 season, excess mortality was mainly in elderly adults. In 2009/10, when pandemic influenza A(H1N1) dominated, excess mortality was mainly in children. The 2010/11 season reflected a similar pattern, although increased mortality in children came later. These patterns were less clear in analyses based on data from individual countries. We have demonstrated that with stratified pooling we can combine local mortality monitoring systems and enhance monitoring of mortality across Europe.

Excess mortality among the elderly in 12 European countries, February and March 2012.

In February and March 2012, excess deaths among the elderly have been observed in 12 European countries that carry out weekly monitoring of all-cause mortality. These preliminary data indicate that the impact of influenza in Europe differs from the recent pandemic and post-pandemic seasons. The current excess mortality among the elderly may be related to the return of influenza A(H3N2) virus, potentially with added effects of a cold snap.

Influenza surveillance during the post-pandemic influenza 2010/11 season in Greece, 04 October 2010 to 22 May 2011.

In this manuscript, we summarise the experience of Greece during the post-pandemic influenza season 2010/11 from 04 October 2010 to 22 May 2011. The spread of the disease and its impact were monitored using multiple surveillance systems, such as sentinel surveillance, virological surveillance and all-cause mortality surveillance. We also focus on the characteristics of laboratory-confirmed severe influenza cases who required admission to an intensive care unit (ICU) (n=368), and/or with a fatal outcome (n=180). The influenza-like illness rate reported from sentinel surveillance started rising in early January 2011 and peaked between 31 January and 6 February 2011. The total number of ICU admissions was higher in the post-pandemic influenza season than during the pandemic period causing a lot of pressure on ICUs. The overall population mortality rate due to influenza A(H1N1)2009 was higher than during the pandemic period (15.9 vs 13.2 fatal cases per million, p=0.087). Our data suggest that the severity of clinical illness in the first post-pandemic influenza season was comparable or even higher than during the pandemic.

Autochthonous Plasmodium vivax malaria in Greece, 2011.

Between May and September 2011, twenty cases of Plasmodium vivax infection were reported in Greek citizens without reported travel history. The vast majority of those cases were confined to a delimited agricultural area of Evrotas, Lakonia. Conditions favouring locally acquired transmission of malaria, including the presence of competent vectors and migrants from endemic countries exist in Greece, underscoring the need for the development of an integrated preparedness and response plan for malaria prevention.

A waterborne Campylobacter jejuni outbreak on a Greek island.

A case-control and a case-crossover study were performed to investigate a Campylobacter jejuni outbreak in Crete in 2009. Most cases originated from rural areas, served by a different water-supply system from that of the adjacent town. Thirty-seven cases and 79 controls were interviewed; cases were interviewed for two different time periods for the case-crossover study. Stool cultures, PFGE and MLST subtyping were run in human samples. Univariately, consumption of tap water was associated with C. jejuni infection. Stratified analysis revealed that water-supply system was an effect modifier of this association. In the multivariable analysis, the rural areas' water supplier and drinking tap water were risk factors. No risk factors were revealed in the case-crossover study. No Campylobacter were isolated in the tested water samples. There is strong epidemiological evidence that tap water was the vehicle of the outbreak.