Simultaneous norovirus outbreak in three Portuguese army bases in the Lisbon region, December 2017.

INTRODUCTION: Norovirus outbreaks frequently occur in communities and institutional settings acquiring a particular significance in armed forces where prompt reporting is critical. Here we describe the epidemiological, clinical and laboratorial investigation of a multicentre gastroenteritis outbreak that was detected simultaneously in three Portuguese army units with a common food supplier, Lisbon region, between 5 and 6 December 2017. METHODS: Questionnaires were distributed to all soldiers stationed in the three affected army units, and stool specimens were collected from soldiers with acute gastrointestinal illness. Stool specimens were tested for common enteropathogenic bacteria by standard methods and screened for a panel of enteric viruses using a multiplex real-time PCR assay. Food samples were also collected for microbiological analysis. Positive stool specimens for norovirus were further genotyped. RESULTS: The three simultaneous acute gastroenteritis outbreaks affected a 31 (3.5%) soldiers from a total of 874 stationed at the three units and lasted for 2 days. No secondary cases were reported. Stool specimens (N=11) were negative for all studied enteropathogenic agents but tested positive for norovirus. The recombinant norovirus GII.P16-GII.4 Sydney was identified in all positive samples with 100% identity. CONCLUSIONS: The results are suggestive of a common source of infection plausibly related to the food supplying chain. Although centralisation of food supplying in the army has economic advantages, it may contribute to the multifocal occurrence of outbreaks. A rapid intervention is key in the mitigation of outbreak consequences and in reducing secondary transmission.

Country-wide surveillance of norovirus outbreaks in the Portuguese Army, 2015-2017.

INTRODUCTION: Gastrointestinal infections are among the most common foodborne and waterborne diseases in military populations, with direct implications in operational efficiency and force readiness. Through the surveillance system of reportable acute gastrointestinal illness in the Portuguese Army, four norovirus outbreaks were identified between October 2015 and October 2017 in mainland Portugal and the Azores archipelago. The present study documents the epidemiological, clinical and laboratory investigations of these norovirus outbreaks. METHODS: Cases were investigated and epidemiological questionnaires were distributed to all soldiers in each military setting where the outbreaks occurred. Stool samples from soldiers with acute gastroenteritis illness were collected and screened for common enteropathogenic agents. Food and water samples served on the settings were also collected for microbiological investigation. Norovirus-positive samples were further characterised by sequence analysis using a public automated genotyping tool. RESULTS: The four outbreaks affected a total of 99 soldiers among the 618 stationed on base units and in a military exercise. A total of 27 soldiers provided a stool sample, of which 20 were positive for norovirus by real-time PCR. Phylogenetic analysis showed that the noroviruses involved were all genogroup II, namely GII.17, GII.Pe-GII.4 Sydney 2012, GII.P2-GII.2 and GII.P16-GII.2. Of note, 30 soldiers had to receive treatment at the military hospital due to severity of symptoms. CONCLUSION: In this short, two-year surveillance period, a total of four norovirus gastroenteritis outbreaks were detected in the Portuguese Army which caused a considerable morbidity, showing once again the impact of norovirus on Army effectiveness and force readiness.

Acute gastroenteritis outbreak associated to norovirus GI.9 in a Portuguese army base.

Gastroenteritis is considered a major illness within the military settings being caused by foodborne enteric pathogens that are particularly easily spread in the crowded conditions of military camps. Gastroenteritis outbreaks caused by norovirus usually affect a great number of soldiers due to the low infectious dose, copious viral shedding, and environmental stability. The present study describes the investigation of an outbreak of acute gastroenteritis that occurred in April 2015 in a Portuguese army base, focusing on the study of the epidemiological curve, symptoms experienced by the affected soldiers, and results of food, water, and stool microbiological analysis. From a total of 938 military personnel stationed on the base 46 soldiers developed acute gastroenteritis. Stool analysis of seven cases showed to be positive for norovirus GI.9 that was the probable cause of the outbreak. This report shows that genogroup I norovirus can also cause considerable morbidity in healthy young soldiers, affecting the operational effectiveness on the military forces. J. Med. Virol. 89:922-925, 2017. © 2016 Wiley Periodicals, Inc.

Multiple enteropathogenic viruses in a gastroenteritis outbreak in a military exercise of the Portuguese Army.

BACKGROUND: Gastroenteritis is one of the most common infectious diseases in the military populations and can diminish operational effectiveness and impede force readiness. OBJECTIVES: The present study investigates the cause and the source of an acute gastroenteritis outbreak that occurred during a military exercise of the Portuguese Army, in February 2013. STUDY DESIGN: A retrospective investigation was performed and stool samples, food items and water were screened for common foodborne bacteria and viruses, namely Norovirus GI, Norovirus GII, Astrovirus, Rotavirus, Adenovirus and Sapovirus. RESULTS: From the total of 160 soldiers that participated in the military exercise 20 developed gastroenteritis (attack rate of 12.5%). Symptoms were predominantly vomiting (n=17, 85%) and diarrhoea (n=9, 45%). The first cases occurred 24-48h after drinking water from the creek, the plausible origin of the outbreak. The epidemic peak was registered 2 days after and the last cases 6 days after, upon returning to base. No pathogenic bacteria were found in stools however virological analysis revealed the presence of multiple enteropathogenic viruses, namely Norovirus GI (GI.3), Norovirus GII (GII.4 New Orleans 2009), Astrovirus and Sapovirus, as single or co-infections. Food and water samples were not tested for the presence of viruses due to exhaustion of samples on bacteriological analysis. CONCLUSIONS: To the best of our knowledge this is the first report of a viral gastroenteritis outbreak among military personnel in the Portuguese Army.