Diarrheal disease continues to be an important cause of morbidity and mortality among young children in developing countries [1]. It is characterized by diarrhea, vomiting and abdominal pain that may lead to hypovolemic shock and dehydration, and subsequently death in severe cases [1]. Worldwide, gastroenteritis affects 3 to 5 billion children each year, and accounts for 1.5 to 2.5 million deaths per year or 12% of all deaths among children less than 5 years of age [2]. In developed countries acute gastroenteritis (AGE) accounts for 300 deaths per year [2].

Globally, rotavirus (RV) is the most common etiological agent for AGE [3]. Data from the coordinated global network for RV surveillance of the World Health Organization at 185 sentinel sites in 64 countries showed RV detection rates of 37-53% in children hospitalized with diarrhea in 2011 in regions of the world where vaccination has not been widely implemented [4] and RV is one of the most common causes of moderate to severe diarrhea during the first 2 years of life [5]. RV vaccination has been widely available for children since 2006 [6] and is now recommended worldwide, a growing body of evidence supports the benefits of its vaccination in the developed and developing world [7].

The protozoan intestinal parasite Entamoeba histolytica is the agent of human amoebiasis. Infection by this parasite is a major cause of morbidity and mortality; it is also responsible for 50 million cases of invasive disease [8] and about 70,000 deaths annually in the world [9]. Both E. histolytica and Giardia lamblia have been listed by the National Institute of Health as category B priority biodefense pathogens due to their low infectious doses and potential for dissemination through compromised food and water supplies in the United States [10]. In developing countries, parasitic diseases represent a social and economic problem with more severe disease associated with young age, malnutrition, and immunosuppression [11].

Despite the heavy burden of AGE especially in children below five years of age, improved prevention is achievable. Personal and food hygiene, including the use of clean water sources, are key measures to prevent transmission of these diseases [12]. Breastfeeding, especially under 6 months of age, also effectively protects infants [12].

A previous recent study in Lebanon showed an increasing prevalence of amoebiasis as the leading cause of hospitalized children for AGE in comparison to others Enteropathogens with data representing mainly the population of Beirut [13]. Our SAGE study prospectively enrolled and tested children admitted for AGE to our hospital, Ragheb Harb Hospital located in Nabatieh, south Lebanon, serving a population of 350,000 habitants and about 35,000 Syrian refugees, during the summer period of 2014, to determine the prevalence and etiology of infectious gastroenteritis by using the routine available tests performed in our hospital laboratory. To our knowledge, few studies have been performed before and reported information regarding the percentage, the age distribution, the risk factors and the protective factors among hospitalized children with AGE in Southern's Lebanon.

From July 2014 to mid-September 2014, we had 222 cases of AGE admitted to the pediatric wards at the Ragheb Harb Hospital, which represented 40.4% (222/549) of total admissions in this period. We enrolled 89.2% (198 of 222 cases) of all gastroenteritis cases admitted at that time, a number that reflects the high burden of AGE on the hospital occupancy rate and on the general health system overall.

Diarrheal diseases are a major public health problem for children in Lebanon, as in other developing countries. Knowledge of the enteropathogens responsible for diarrheal illnesses is essential for implementation of appropriate public and hospital health measures to control these diseases [14]. This single center study was conducted in the summer period of the year 2014 during the peak season of diarrheal diseases. It is one of the few studies conducted in Lebanon to determine the enteropathogens implicated in the pathogenesis of acute diarrheal diseases in hospitalized children using the common laboratory methods [13]. In this study we enrolled 198 pediatric cases with AGE representing 89% of all children admitted to our hospital with AGE for the entire period of the study that constituted about 40% of the total pediatric admissions.

In our study we identified the enteropathogens in about 58% of AGE cases by using the routine laboratory methods which is slightly below the 66%, the number identified by Youssef et al. [14] in Jordan in 2000, but they were using a combination of traditional and molecular diagnostic techniques. Of the 58% of detected pathogens, 51% (101 of 198) were single pathogens cases of AGE and 7% (13 of 198) were due to mixed pathogens, which is a little lower than the number of 9.8% of co-infection reported in a Bulgarian study in 2015 [15].

Our study showed that the percentage of E. histolytica AGE was 26.3% (52 of 198) which was in correlation with the previous reported prevalence of 22% reported at the Makassed General Hospital in Beirut in 2013 [13] and very similar to the reported prevalence of 25.9% reported also in Tajikistan by in 2011 [16]. Moreover, the age distribution of amoebiasis was the following: 34% (18/52) were below one year old and constituted 20% as shown in Table 1, which is an unusual presentation in this age group because E. histolytica is usually transmitted via fecal oral route with contaminated food and water, so young infants are less likely to develop intestinal amebiasis very often [17]. That means that the drinking water used for milk preparation and the tap water used for daily home and body hygiene was contaminated and could be orally aspirated or ingested during bathing or face washing especially when parents were holding their baby in face down position, a procedure that could be easily adjusted by preventing the water coming into the mouth of the baby or by using clean water for daily facial wash; to be noted that the prevalence of E. histolytica in stool was increasing with age especially after the age of five years.

The second major enteropathogen found was RV, causing 19 % of AGE admissions to our hospital as a single pathogen, which was slightly lower than the previous reported results in 2013 in Lebanon [18]. Many countries in the world have reported that RV is a leading cause of pediatric AGE, accounting for 27-51% of all diarrhea cases in children less than 5 years of age [19].

As found in different studies from the Eastern Mediterranean region, RV AGE disease burden in our study was highest in children less than 5 years of age 92% of our reported cases [20]. The prevalence of RV infection during the summer months was found in our study was an interesting observation; In general, RVs causes diarrheal illnesses around the year, but predominantly during the winter months in countries with temperate climates. Temperature and relatively humid weather conditions have been proposed to contribute to increased RV infection. However, a few of the virus characteristics such as environmental stability, heat resistance and easy transmission by the fecal-oral route foster the spread of infections also during summer season. Diarrheal viruses such as RV, spread mainly through contact with infected persons, contaminated environmental surfaces or via ingestion of contaminated food and water. The emergence of a new virus variant in the susceptible child population may potentially be factors that favor the spread of virus gastroenteritis agents during the summer months [15].

Adenoviruses are ubiquitous agents that infect people of all ages, we identified the presence of adenovirus as a single agent in 6% of cases, this percentage will be doubled if we take into account both single and mixed infections, Adenoviruses have long been suspected to cause diarrhea and there is a long term asymptomatic shedding of certain serotypes from the stools after adenovirus respiratory infection, the group F adenoviruses (serotypes 40 and 41) are strongly associated with diarrheal disease in children; diarrhea induced by adenovirus type 41 may be more protracted than disease caused by adenovirus type 40 [21].

In our study, we have 42.4% of cases with unidentified causes or pathogens, a remarkable percentage that is when added to the negative stool cultures performed for only 17 cases, we could initiate further needed steps to improve our ability for more pathogens identification by increasing the number of cultures performed for hospitalized children with suspected invasive AGE in order to cultivate more pathogenic bacteria.

Concerning the clinical manifestations, we studied three clinical parameters among them: fever in 76.8%, vomiting in 71.2% and diarrhea in 93.4% of patients as the most common presenting symptoms in our study population which are not informative as it will be if we considered the determination of Vesikari score, used for severity estimation of AGE. We noted that in both the amebiasis and the unidentified pathogens group, there was an elevated CRP in comparison to viral groups which means that in the unidentified pathogens group the possibility an invasive infections is highly suggestive.

The average length of hospital stay (LOS) was 3.5 days and it was quite similar for the four groups and when compared with the two RV group based on either vaccinated and not vaccinated patients, the LOS did not differ between them in accordance to previous results reported in a Lebanese study in 2016 [22].