The passage of greater than or equal to three loose or liquid stools per day describes diarrhea. On a personalized context, it could be depicted as more frequent passage than is normal for an individual per time interval of stooling episode. The trends and symptomatology of diarrhea illness depends on the etiologic agent and the health state of the host. A good example is the fact that rotavirus caused diarrhea is commonly associated with vomiting, severe dehydration, and a probable number of work days lost than non-rotavirus gastroenteritis. This example is supported by a documented prospective study conducted in the United States in 604 children aged 3-36 months prior to introduction to rotavirus vaccine which revealed that the highest incidence of diarrhea is between the months of January and August. This period usually coincides to the On the other hand, there have been misconceptions with regards to the definition of diarrhea and what depicts a diarrhea. Based on this, it is vital to note that perceived frequent passing of formed stools and passing of loose, “pasty” stools by breastfed babies is not diarrhea. It can be described based on onset of action as acute and chronic diarrhea. It can also be described based on the presence of blood in stool as dysentery. Another descriptive approach is via causative mechanisms eg. Infectious diarrhea, drug induced diarrhea etc. Knowledge of the stool consistency, volume, frequency and color can be vital in determining whether the problematic source in the gastro-intestinal tract.IncidenceMost statistics on diarrhea episodes and events are usually prevalence. This is due to the fact that most cases of diarrhea are benign, super acute in nature and easily self resolves. Based on this, it is difficult to estimate the incidence. It is noteworthy that hospital facilities with high frequency of diarrhea, health professionals find it difficult to distinguish one episode from the next. A good level of clinical suspicion and closed disease surveillance is required to note the beginning and the end of each diarrhea episodes. Diarrheal disease is the second leading cause of death in children of under five years old, and is responsible for killing around 525,000 children every year. The most documented Incidence of diarrheal diseases was usually observed to be maximum during the summer as compared to other weather seasons of the year.PathogenesisThe gastrointestinal tract mechanisms that regulate ionic balance, fluid absorption and is a very complex set up. Homeostatic disruptions of the GIT by bacterial enterotoxins, bile acids and neoplasm-derived by-product can lead to watery stool.  Hence, determining the cause of diarrhea can be a difficult challenge. Based on normal physiology, the GIT maintains homeostasis via various ionic transport proteins/complexes which are targeted to the apical, basal or basolateral membranes of its epithelial cells. Cations and anions transport proteins are regulated by endogenous activators like cAMP, PGE2, Ca; also dietary-related factors – bile acids, and through post-translational modifications like phosphorylation. Sometimes, the pathophysiologic states leads to a homeostatic ionic/fluid exchange dysfunction as a result of decompensated pro-absorptive/anti-secretory mechanisms. Thus, the resultant excessive secretion of Na and Cl ions with follow up release of a large amount of H2O into the colon results in diarrhea, which can be life-threatening if not ameliorated. Diarrhea from infectious organisms (e.g. bacteria, protozoa, viruses) utilize a different mechanism of action to cause intestinal disease. These mechanisms include disruption of tight junctions, alterations in ion transport and elicitation of inflammatory responses. Other documented pathophysiologic mechanism are those incited by extra-colonic or colonic neoplasms, inflammatory bowel disease conditions, and those infected with certain pathogens. Clinical ManifestationThe clinical features and course of diarrhea generally depends on its etiology and on the host health condition. However, the common signs and symptoms of diarrhea include:Dehydration: This manifests as lethargy, depressed consciousness, sunken anterior fontanel, dry mucous membranes, sunken eyes, lack of tears, poor skin turgor, delayed capillary refill.Failure to thrive and malnutrition: Patients presents with reduced muscle/fat mass or peripheral edema due to chronicity of the event.Abdominal pain/cramping and BorborygmiSigns of low blood pressureFeverEtiologyIn order to determine the source of diarrhea incidence, we need to consider the stool characteristics (consistency, odor, color, frequency, volume) and presence of associated enteric symptoms like nausea, fever and abdominal. Based on the stool characteristics, the following are utilized in history taking to identify causality:Use of child daycare-  Rotavirus, Astrovirus, Calicivirus; Campylobacter, Shigella, Giardia, and Cryptosporidium species.Food ingestion history- Raw/Contaminated foods, food poisoningWater exposure like marine environment and swimmingCamping history- Possible exposure to contaminated waterTravel history- Exposure to contaminated water with pathogens that affect specific regions; also consider Rotavirus, Shigella, Salmonella, and Campylobacter spp regardless of specific travel history, as these organisms are prevalent worldwideAnimal exposure- young dogs/cats are vectors for Campylobacter spp; turtles are vectors for Salmonella sppPredisposing conditions- Hospitalization, Prior antibiotics use, Immunocompromised stateMost common means of transmission of diarrheal germs are spread usually from the stool of one person to the mouth of another. Some of the ways Water, food, and objects become contaminated with stool include: People and animals that defecate in or near water sources that people drink, contaminated water used for crop irrigation, carelessness amongst chefs who prepare meals by poor hand washing etiquette and touching of objects, such as doorknobs, tools, or cooking utensils with contaminated hands. See Table 1 & 2 for the comprehensive list of etiological agents.EpidemiologyDiarrheal diseases remain the leading cause of morbidity and mortality in children worldwide. Reliable field data from epidemiological studies are important to study diarrhea epidemiology and the effect of interventions but diarrhea remains a condition difficult to measure due to its acute nature.Globally over four billion episodes of diarrhea have been estimated to occur every year with > 90% occurring in developing countries. It is also an important public health problem especially with regards to the under-five children in developing countries. A study in India showed that total deaths from diarrheal disease in India among children aged 0-6 years was estimated to be 158,209 per year and the proportionate mortality in this age group was 9.1%.In America, approximately 179 million cases of acute diarrhea occur on yearly basis and almost all cases have preventable causality. The average estimated incidence of diarrhea in children aged 0-6 years was 1.71 and 1.09 episodes/person/year in rural and urban areas. Studies have shown that the incidence of acute diarrheal diseases was as low as 1 episode/child/year in some urban areas as compared to the rural area. Similar studies also revealed that families of more than 3 members had acute diarrhea that was 22-70% higher than family with just one child < 5 year old.Other documented predisposing factors include young age, presence of under-five sibling in the family, low socioeconomic status, poor maternal literacy, birth weight, poor sanitation, inadequate breastfeeding, malnutrition and maternal hygiene practices are associated with a higher incidence of diarrheal diseases.Diagnostic TestMost cases of diarrhea resolve without treatment, and a doctor will often be able to diagnose the problem without tests. If there is chronic or persistent diarrhea, the ordered test is according to the suspected underlying cause. The following tests are needed for diagnosis:Stool test: It may be required especially in extreme of ages (young and elderly). Other indications include signs of fever or dehydration, bloody stool or pus in stool, associated severe abdominal pain, positive weakened immune system, associated low blood pressure, prior hospital admission, history of travel to a developing country and diarrhea episode persisting more than a week.Full blood count: Derangement in the red blood cell and elevated platelet count usually denotes inflammatory cause.Liver function tests: Assessing the albumin level is vital especially in cases of chronic diarrhea.Tests for malabsorption: This is important in order to monitor important micro and macronutrients especially calcium, vitamin B-12, and folate. They can be used to monitor iron homeostasis and thyroid function.Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP): Elevated levels may indicate inflammatory bowel disease (IBD).Testing for antibodies: This is more specific to disease like celiac disease.Prevention and ControlAs a Public Health advocate, the most effective way to manage diarrhea is to ensure that it does not happen in the first place. In order to achieve this, a lot of the impetus is centered on the behavioral change at the individual level to enforcement of universal precautions at the community level. Recent advances in science have led to the development of an effective rotavirus vaccine which is part of the routine immunization schedule for children. This vaccine has aided in the reduction of the prevalence of Rotavirus diarrhea. Other methods of prevention include:Ensuring access to safe drinking-waterEncourage the use of improved sanitationAdequate hand washing etiquette with soapAdvising mothers to be advocate of exclusive breastfeeding for the first six months of life to prevent protein energy malnutritionImproving good personal and food hygiene to reduce morbidity and mortality of diarrheaHealth awareness and continuous education on infection transmission process.Public Health SignificanceDiarrheal diseases account for 1 in 9 child deaths worldwide based on statistics for CDC 2018 report, making diarrhea the second leading cause of death among children under the age of 5yrs. The morbidity and mortality of diarrhea is even more deadly for children with HIV co-infection as the death rate is 11 times higher than the rate for children without HIV. Chronic diarrhea also have a negative impact on childhood growth and cognitive development. A study by Zimmerman et al showed that yearly average of 1,186 diarrhea-associated hospitalizations (35 per 10,000 children <5 years) and 33 386 outpatient visits (943 per 10,000 children <5 years) were reported, accounting for 4% of all hospitalizations and 2% of all outpatient visits among children <5 years of age. They also reported that the median cost of a diarrhea-associated hospitalization was $2,307, and that for a rotavirus-associated hospitalization was $2,303. Median costs of diarrhea- and rotavirus-associated outpatient visits were $47 and $57, respectively. Irrespective of these negative statistics, efforts made over the last 20 towards prevention and control of diarrhea incidence has been cost effective as every $1 invested yields an average return of $25.50.For children 5 years of age and older, adolescents and adults alike, mild to moderate diarrhea can lead to absenteeism from school or work and occasionally may require hospital visit. More severe diarrhea can lead to hospital admissions due to serious sequelae such as Guillain Barre’ syndrome and hemolytic uremic syndrome and in some cases death. In 2015, there 526?000 deaths due to diarrhea in children younger than 5 years, which was a 57% drop from the 1?213?000 estimated deaths in 2000. This major drop in statistics could be due to the effort of Public health impact towards control and prevention.Though most diarrhea episodes are self-limiting and dehydration could be controlled with oral rehydration therapy, it is ideal to be able to prevent diarrhea. Some prevention strategies like vaccines have benefited greatly from a comprehensive understanding of the overall burden of pathogen-specific diarrheal disease. A vaccine for cholera that has been available for several years, and now recommended by the WHO typifies this for people living in endemic areas.Referenceshttp://www.who.int/news-room/fact-sheets/detail/diarrhoeal-diseaseVesikari T, Matson DO, Dennehy P, Van Damme P, Santosham M, Rodriguez Z, Dallas MJ, Heyse JF, Goveia MG, Black SB, Shinefield HR, Christie CD, Ylitalo S, Itzler RF, Coia ML, Onorato MT, Adeyi BA, Marshall GS, Gothefors L, Campens D, Karvonen A, Watt JP, O’Brien KL, DiNubile MJ, Clark HF, Boslego JW, Offit PA, Heaton PM, Rotavirus Efficacy and Safety Trial (REST) Study Team. N Engl J Med. 2006 Jan 5; 354(1):23-33.Fischer Walker CL, Sack D, Black RE. Etiology of diarrhea in older children, adolescents and adults: a systematic review. PLoS Negl Trop Dis. 2010;4(8):e768. Published 2010 Aug 3. doi:10.1371/journal.pntd.0000768Schmidt WP, Arnold BF, Boisson S, et al. Epidemiological methods in diarrhoea studies–an update. Int J Epidemiol. 2011;40(6):1678-92.Lakshminarayanan S, Jayalakshmy R. Diarrheal diseases among children in India: Current scenario and future perspectives. J Nat Sci Biol Med. 2015;6(1):24-8.Turvill JL, Connor P, Farthing MJG. Neurokinin 1 and 2 receptors mediate cholera toxin secretion in rat jejunum. Gastroenterology 2000;119:1037– 44.Payne CM, Fass R, Bernstein H, Giron J, Bernstein C, Dvorak K, Garewal H. Pathogenesis of diarrhea in the adult: diagnostic challenges and life-threatening conditions. Eur J Gastroenterol Hepatol. 2006;18:1047–1051.Herbert L. DuPont. Acute Infectious Diarrhea in Immunocompetent Adults. New England Journal of Medicine, 2014; 370 (16): 1532 DOI: 10.1056/NEJMra1301069Zimmerman CM, Bresee JS, Parashar UD, Riggs TL, Holman RC, Glass RI. Cost of diarrhea-associated hospitalizations and outpatient visits in an insured population of young children in the United States. Pediatr Infect Dis J. 2001;20(1):14–19.https://www.cdc.gov/healthywater/pdf/global/programs/globaldiarrhea508c.pdfTable 1-Causes of diarrhea with acute onsetInfectionsEnteric infections (including food poisoning)Extraintestinal infectionsDrug-InducedAntibiotic-associatedLaxativesAntacids that contain magnesiumOpiate withdrawalOther drugsFood AllergiesCow’s milk protein allergySoy protein allergyMultiple food allergiesOlestraMethylxanthines (caffeine, theobromine, theophylline)Disorders of digestive/absorptive functionGlucose-galactose malabsorptionSucrase-isomaltase deficiencyLate-onset (adult-type) hypolactasia, resulting in lactose intoleranceSurgical ConditionsAcute appendicitisIntussusceptionVitamin DeficienciesNiacin deficiencyFolate deficiencyVitamin toxicityVitamin CNiacin, vitamin B3Ingestion of heavy metals or toxins (eg, copper, tin, zinc)Ingestion of plants (eg, hyacinths, daffodils, azalea, mistletoe, Amanitaspecies mushroomsTable 2-Infectous causes of acute diarrheaParasitesCryptosporidium - 1-3% of casesG lamblia - 1-3% of casesBacteriaCampylobacter jejuni - 6-8% of casesSalmonella - 3-7% of casesE Coli - 3-5% of casesShigella - 0-3% of casesY enterocolitica - 1-2% of casesC difficile - 0-2% of casesVibrio parahaemolyticus - 0-1% of casesV cholerae - UnknownAeromonas hydrophila - 0-2% of casesVirusRotavirus – 25-40% of casesNorovirus – 10-20% of casesCalicivirus – 1-20% of casesAstrovirus – 4-9% of casesEnteric-type adenovirus – 2-4% of casesGet Help With Your EssayIf you need assistance with writing your essay, our professional essay writing service is here to help!Find out more