Application of the susceptible–infected–recovered deterministic model in a GII.P17 emergent norovirus strain outbreak in Romania in 2015

Abstract

Emilian Damian Popovici,1,2 Dana Gabriela Negru,3 Teodora Olariu,4 Mariana Nagy,5 Sorin Dinu,6 Gabriela Oprisan,6,7 Lavinia Zota,8 Luminita Mirela Baditoiu11Epidemiology Department, “Victor Babeş” University of Medicine and Pharmacy, Timişoara, Romania; 2National Institute of Public Health, Regional Public Health Centre, Timişoara, Romania; 3Private Medical Epidemiology Practice, Arad, Romania; 4Arad County Clinical Hospital, Arad, Romania; 5Department of Mathematics and Computer Science, "Aurel Vlaicu" University of Arad, Arad, Romania; 6Molecular Epidemiology Laboratory, Cantacuzino National Medical – Military Institute of Research and Development, Bucharest, Romania; 7Faculty of Pharmacy, "Titu Maiorescu" University, Bucharest, Romania; 8National Institute of Public Health, National Centre for Surveillance and Control of Communicable Diseases, Bucharest, RomaniaCorrespondence: Emilian Damian PopoviciEpidemiology Department, “Victor Babeş” University of Medicine and Pharmacy, No. 2, Piata Eftimie Murgu, Timişoara 300041, RomaniaTel [phone]Fax [phone]Email [email protected]: This study shows the epidemiological profile of the first gastroenteritis outbreak of GII.P17 in the Romanian territory. An outbreak with such large amplitude in a European territory was previously undocumented.Patients and methods: Using a cross-sectional design, with the susceptible-infected-recovered (SIR) deterministic compartmental model for a fixed population, and the cluster method for establishing the high-incidence zones, we carried out our investigation by means of questionnaires containing personal data, affected collectivities, disease onset and duration, symptoms displayed, medical assistance provided, previous antibiotic intake where applicable, food consumption and water sources, and sanitation conditions. The confirmation of cases was done based on the typical norovirus gastroenteritis symptomatology and using three laboratory confirmations (by molecular diagnosis) for GII.P17-GII.17 genotype noroviruses from three patients.Results: A gastroenteritis outbreak occurred in October–November 2015, affecting 328 people in Arad, a county in Western Romania, covering 44 neighbouring localities with a total population of 35,440 people. The study detected an inter-human transmission of the infection, with an intrafamilial risk of disease of 2.26 (95% CI 1.76 to 2.90) compared with the community transmission (in school collectivity). The basic reproduction number Ro dropped from 1.26 to 0.18 during weeks 43:44, after controlling the transmission by decontamination and isolation.Conclusion: SIR made it possible to highlight the expansion of the emerging norovirus strain infection from community to family collectivities. This study provides practical solutions to limit disease cases, even in the absence of etiology, and shows the importance of sometimes underestimated traditional control methods.Keywords: norovirus, GII.17_Kawasaki, SIR, basic reproduction number

Keywords

• norovirus
• GII.17_Kawasaki
• SIR
• basic reproduction number