Rotavirus Gastroenteritis. Epidemiology and genotype distribution.

Doctoral Dissertation uoadl:2885976 138 Read counter

Τομέας Υγείας - Μητέρας - Παιδιού
Library of the School of Health Sciences
Deposit date:
Koukou Dimitra-Maria
Dissertation committee:
Συριοπούλου Βασιλική, Ομότιμη Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Παπαγρηγορίου-Θεοδωρίδου Μαρία, Ομότιμη Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Ελευθερία Ρώμα, Ομότιμη Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Γεώργιος Χρούσος, Ομότιμος Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Γεώργιος Δαΐκος, Ομότιμος Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Αθανάσιος Μίχος, Αναπληρωτής Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Σιαχανίδου Σουλτάνα, Αναπληρώτρια Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Original Title:
Γαστρεντερίτιδα από Ρότα ιό. Επιδημιολογία και κατανομή Γονοτύπων.
Translated title:
Rotavirus Gastroenteritis. Epidemiology and genotype distribution.
Introduction: Rotavirus (RV) is the leading cause of acute gastroenteritis among young children worldwide and major cause of deaths in developed countries, especially in Africa and Asia. In 2006 two vaccines against RV were licensed and reduction to morbidity and mortality due to RV was reported. Five are the RV genotypes that affect humans mostly; G1P[8], G2P[4], G3P[8], G4P[8] and G9P[8]. Their prevalence is estimated between 63-97% worldwide and differs from country to country and year to year. RV vaccines are safe and highly effective towards the above genotypes. RV surveillance networks are established around the world to collect epidemiological and genotyping data, so as to monitor changes in the epidemiology of RV due to the universal mass vaccination and detect the emergence of new RV strains.
Objectives: Study the epidemiology of RV infection and describe the distribution of RV genotypes in Greece during the early and late post vaccine era.
Materials and methods: A prospective multi-center study was conducted in 20 Pediatric Hospitals around Greece during 7 consecutive seasons (2008-2014). Faecal samples were obtained from children <5years old, presenting symptoms of acute gastroenteritis and tested for the presence of RV group A antigen by immunonochromatography (VIKIA Rota-Adeno test, Biomerieux). Positive samples were sent to the «Choremio Research Laboratory» in Athens and genotyped by RT-PCR and Multiplex Nested PCR using primers for the VP7 and VP4 RV genes. Samples were further G and P characterized by using gel electrophoresis and UV lighting. Additionally epidemiological data (date, gender, age, residence, clinical symptoms, hospitalization status and vaccination status) were collected from children with RV gastroenteritis. RV season was determined as the period between September and August of the next year. The duration of the study was seven RV seasons which were further grouped into early (2008-2011) and late (2011-2014) post vaccine periods. Epidemiological data were analyzed with the «SPSS statistical package» and correlated with the RV genotyping results. Finally a comparison between results of the early (2008-2011) and the late (2011-2014) post vaccine period was made.
Results: A total of 2528 children (54.5% male) of median age 20.2 ± 18 months participated in the study. Most of them (80%) were under 3 years old and 95.4% were hospitalized. Nosocomial infection was detected in 19.2% of children with RV gastroenteritis. RV samples were collected from children living in the region of Attica (76.6%) and in other 9 geographical regions of Greece (23.4%) covering in total the 93.2% of the population of Greek children <5 years old. Urban regions of Greece was the place of living for 80.7% of children. At least one dose of vaccine was implemented in 43 children (1.7%). Symptoms of severe gastroenteritis were found in 72.4% of children. The number of samples collected from each season was between 233-560 except from the first season which was shorter and only 67 samples were collected. Increase in the number of RV samples was reported every second season of the study. Most of the RV samples were collected between January and April (52%) and RV peak was reported periodically either in Winter or Spring. Totally 2100 samples were genotyped and 94.8%, of them were the common genotypes; G4P[8] 45.2%, G1P[8] 25.2%, G2P[4] 17%, G3P[8] 2.4%, G9P[8] 2.6% and G12P[8] 2.4%. Other genotypes that were detected were; uncommon combinations of the above genotypes (1%), possible animal originated (1.4%) and mixed genotypes (2.8%). Even if changes of the prevalent genotypes were mentioned from year to year and place to place, two genotypes G4P[8] and G1P[8] were the most prevalent during the study with annual highest percentages of 39.3-74.2% and 50.1-78.1% respectively. Statistical significant association was found between older children and animal originated genotypes as well as between severe gastroenteritis and genotypes G3P[8] and G12P[6]. Comparison between the early post vaccine period and the late post vaccine period showed an earlier and shorter peak of RV season during the latter period. Also increase in the mean age of children and increase in the prevalence of G2P[4], G3P[8], G4P[8] and G9P[8] genotypes was mentioned during the late post vaccine period.
Conclusions: This study showed changes in the epidemiology and diversity of RV strains during the late post vaccination period in Greece despite the low vaccine coverage. Similar changes have been reported by several countries (UK, Belgium, Austria, USA) that have implemented massive vaccination and have achieved high vaccine coverage. It is not clear yet whether these changes can be attributed to the implementation of RV vaccination or to the natural fluctuation of the virus. Continuous surveillance of RV epidemiology is needed to elucidate the previous question. Further molecular and phylogenetic analysis of RV genotypes may contribute to understand better the evolution’s pattern of the Rotavirus and to monitor the emergence of possible new RV genotypes under the vaccine-induced selection pressure, which could lead to an alteration of vaccines effectiveness.
Main subject category:
Health Sciences
Rotavirus, Genotypes, Children, Gastroenteritis, Epidemiology
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