Diagnosis of infection with rotavirus normally follows diagnosis of gastroenteritis as the cause of severe diarrhoea. Most children admitted to hospital with gastroenteritis are tested for

Specific diagnosis of infection with is made by finding the virus in the child's stool by enzyme immunoassay. There are several licensed test kits on the market which are sensitive, specific and detect all serotypes of . Other methods, such as electron microscopy and PCR (polymerase chain reaction), are used in research laboratories. Reverse transcription-polymerase chain reaction (RT-PCR) can detect and identify all species and serotypes of human rotavirus.

Diagnosis of infection with rotavirus normally follows diagnosis of gastroenteritis as the cause of severe diarrhoea. Most children admitted to hospital with gastroenteritis are tested for

Specific diagnosis of infection with is made by finding the virus in the child's stool by enzyme immunoassay. There are several licensed test kits on the market which are sensitive, specific and detect all serotypes of . Other methods, such as electron microscopy and PCR, are used in research laboratories. Reverse transcription-polymerase chain reaction (RT-PCR) can detect and identify all species and serotypes of human rotavirus.

Rotavirus is highly contagious and cannot be treated with antibiotics or other drugs. Because improved sanitation does not decrease the prevalence of rotaviral disease, and the rate of hospitalisations remains high despite the use of oral rehydrating medicines, the primary public health intervention is vaccination. In 1998, a rotavirus vaccine was licensed for use in the United States. Clinical trials in the United States, Finland, and Venezuela had found it to be 80 to 100% effective at preventing severe diarrhoea caused by rotavirus A, and researchers had detected no statistically significant serious adverse effects. The manufacturer, however, withdrew it from the market in 1999, after it was discovered that the vaccine may have contributed to an increased risk for intussusception, a type of bowel obstruction, in one of every 12,000 vaccinated infants. The experience provoked intense debate about the relative risks and benefits of a rotavirus vaccine.

In 2006, two new vaccines against infection were shown to be safe and effective in children, and in 2009, the WHO recommended that rotavirus vaccine be included in all national immunisation programmes.

The incidence and severity of rotavirus infections has declined significantly in countries that have acted on this recommendation. A 2014 review of available clinical trial data from countries routinely using rotavirus vaccines in their national immunisation programs found that rotavirus vaccines have reduced rotavirus hospitalisations by 49–92 percent and all cause diarrhoea hospitalisations by 17–55 percent. In Mexico, which in 2006 was among the first countries in the world to introduce rotavirus vaccine, diarrhoeal disease death rates dropped during the 2009 rotavirus season by more than 65 percent among children age two and under. In Nicaragua, which in 2006 became the first developing country to introduce a rotavirus vaccine, severe rotavirus infections were reduced by 40 percent and emergency room visits by a half. In the United States, rotavirus vaccination since 2006 has led to drops in rotavirus-related hospitalisations by as much as 86 percent. The vaccines may also have prevented illness in non-vaccinated children by limiting the number of circulating infections. In developing countries in Africa and Asia, where the majority of rotavirus deaths occur, a large number of safety and efficacy trials as well as recent post-introduction impact and effectiveness studies of Rotarix and RotaTeq have found that vaccines dramatically reduced severe disease among infants. In September 2013, the vaccine was offered to all children in the UK, aged between two and three months, and it is expected to halve the cases of severe infection and reduce the number of children admitted to hospital because of the infection by 70 percent. In Europe, hospitalisation rates following infection by rotavirus have decreased by 65% to 84% following the introduction of the vaccine. Globally, vaccination has reduced hospital admissions and emergency department visits by a median of 67%.

Rotavirus vaccines are licensed in over 100 countries, and more than 80 countries have introduced routine rotavirus vaccination, almost half with the support of Gavi, the Vaccine Alliance. To make rotavirus vaccines available, accessible, and affordable in all countries—particularly low- and middle-income countries in Africa and Asia where the majority of rotavirus deaths occur, PATH (formerly Program for Appropriate Technology in Health), the WHO, the U.S. Centers for Disease Control and Prevention, and Gavi have partnered with research institutions and governments to generate and disseminate evidence, lower prices, and accelerate introduction.

Because improved sanitation does not decrease the prevalence of rotaviral disease, and the rate of hospitalisations remains high, despite the use of oral rehydrating medicines, the primary public health intervention is vaccination. Two rotavirus vaccines against Rotavirus A infection are safe and effective in children: Rotarix by GlaxoSmithKline and RotaTeq by Merck. Both are taken orally and contain attenuated live virus.

Rotavirus vaccines are licensed in more than 100 countries, but only 17 countries have introduced routine rotavirus vaccination. Following the introduction of routine rotavirus vaccination in the US in 2006, the health burden of rotavirus gastroenteritis "rapidly and dramatically reduced" despite lower coverage levels compared to other routine infant immunizations. Clinical trials of the Rotarix rotavirus vaccine in South Africa and Malawi, found that the vaccine significantly reduced severe diarrhoea episodes caused by rotavirus, and that the infection was preventable by vaccination. A 2012 Cochrane review of 41 clinical trials that included 186,263 participants concluded Rotarix and RotaTeq are effective vaccines. Additional rotavirus vaccines are under development. The World Health Organization(WHO) recommends that rotavirus vaccine be included in all national immunisation programmes. The incidence and severity of rotavirus infections has declined significantly in countries that have acted on this recommendation.

The Rotavirus Vaccine Program is a collaboration between PATH, the (WHO), and the U.S. Centers for Disease Control and Prevention, and is funded by the GAVI Alliance. The Program aims to reduce child morbidity and mortality from diarrhoeal disease by making a vaccine against rotavirus available for use in developing countries.

A determination of whether or not the person has dehydration is an important part of the assessment, with dehydration typically divided into mild (3–5%), moderate (6–9%), and severe (≥10%) cases. In children, the most accurate signs of moderate or severe dehydration are a prolonged capillary refill, poor skin turgor, and abnormal breathing. Other useful findings (when used in combination) include sunken eyes, decreased activity, a lack of tears, and a dry mouth. A normal urinary output and oral fluid intake is reassuring. Laboratory testing is of little clinical benefit in determining the degree of dehydration. Thus the use of urine testing or ultrasounds is generally not needed.

Gastroenteritis is typically diagnosed clinically, based on a person's signs and symptoms. Determining the exact cause is usually not needed as it does not alter management of the condition.

However, stool cultures should be performed in those with blood in the stool, those who might have been exposed to food poisoning, and those who have recently traveled to the developing world. It may also be appropriate in children young than 5, old people, and those with poor immune function. Diagnostic testing may also be done for surveillance. As hypoglycemia occurs in approximately 10% of infants and young children, measuring serum glucose in this population is recommended. Electrolytes and kidney function should also be checked when there is a concern about severe dehydration.

In 2012, the World Health Organization estimated that vaccination prevents 2.5 million deaths each year. If there is 100% immunization, and 100% efficacy of the vaccines, one out of seven deaths among young children could be prevented, mostly in developing countries, making this an important global health issue. Four diseases were responsible for 98% of vaccine-preventable deaths: measles, "Haemophilus influenzae" serotype b, pertussis, and neonatal tetanus.

The Immunization Surveillance, Assessment and Monitoring program of the WHO monitors and assesses the safety and effectiveness of programs and vaccines at reducing illness and deaths from diseases that could be prevented by vaccines.

Vaccine-preventable deaths are usually caused by a failure to obtain the vaccine in a timely manner. This may be due to financial constraints or to lack of access to the vaccine. A vaccine that is generally recommended may be medically inappropriate for a small number of people due to severe allergies or a damaged immune system. In addition, a vaccine against a given disease may not be recommended for general use in a given country, or may be recommended only to certain populations, such as young children or older adults. Every country makes its own vaccination recommendations, based on the diseases that are common in its area and its healthcare priorities. If a vaccine-preventable disease is uncommon in a country, then residents of that country are unlikely to receive a vaccine against it. For example, residents of Canada and the United States do not routinely receive vaccines against yellow fever, which leaves them vulnerable to infection if travelling to areas where risk of yellow fever is highest (endemic or transitional regions).

The WHO lists 25 diseases for which vaccines are available:

1. Measles

2. Rubella

3. Cholera

4. Meningococcal disease

5. Influenza

6. Diphtheria

7. Mumps

8. Tetanus

9. Hepatitis A

10. Pertussis

11. Tuberculosis

12. Hepatitis B

13. Pneumoccocal disease

14. Typhoid fever

15. Hepatitis E

16. Poliomyelitis

17. Tick-borne encephalitis

18. Haemophilus influenzae type b

19. Rabies

20. Varicella and herpes zoster (shingles)

21. Human papilloma-virus

22. Rotavirus gastroenteritis

23. Yellow fever

24. Japanese encephalitis

25. Malaria

26. Dengue fever

Cultures of stool samples are examined to identify the organism causing dysentery. Usually, several samples must be obtained due to the number of amoebae, which changes daily. Blood tests can be used to measure abnormalities in the levels of essential minerals and salts.

A clinical diagnosis may be made by taking a history and doing a brief examination. Treatment is usually started without or before confirmation by laboratory analysis.

With most infections, the key is to block the spread of the organism.

- Wash hands frequently

- Eat properly prepared and stored food.

- Bleach soiled laundry

- Vaccinations for "Vibrio cholerae" and rotavirus have been developed. Rotavirus vaccination is recommended for infants in the U.S. Vaccines for "V. cholerae" may be administered to individuals traveling to at-risk areas

The doctor will take a medical history to make sure that nothing else is causing the symptoms. Also, the doctor might perform a rectal or abdominal examination to exclude the possibilities of inflammatory bowel disease (e.g., Crohn’s disease) and pelvic abscesses (pockets of pus). A stool culture (a laboratory test to identify bacteria and other organisms from a sample of feces) can be used to determine the specific virus or germ that is causing gastroenteritis.

Isolation is the implementation of isolating precautions designed to prevent transmission of microorganisms by common routes in hospitals. (See Universal precautions and Transmission-based precautions.) Because agent and host factors are more difficult to control, interruption of transfer of microorganisms is directed primarily at transmission for example isolation of infectious cases in special hospitals and isolation of patient with infected wounds in special rooms also isolation of joint transplantation patients on specific rooms.

Controlling nosocomial infection is to implement QA/QC measures to the health care sectors, and evidence-based management can be a feasible approach. For those with ventilator-associated or hospital-acquired pneumonia, controlling and monitoring hospital indoor air quality needs to be on agenda in management, whereas for nosocomial rotavirus infection, a hand hygiene protocol has to be enforced.

To reduce HAIs, the state of Maryland implemented the Maryland Hospital-Acquired Conditions Program that provides financial rewards and penalties for individual hospitals based on their ability to avoid HAIs. An adaptation of the Centers for Medicare & Medicaid Services payment policy causes poor-performing hospitals to lose up to 3% of their inpatient revenues, whereas hospitals that are able to avoid HAIs can earn up to 3% in rewards. During the program’s first 2 years, complication rates fell by 15.26 percent across all hospital-acquired conditions tracked by the state (including those not covered by the program), from a risk-adjusted complication rate of 2.38 per 1,000 people in 2009 to a rate of 2.02 in 2011. The 15.26-percent decline translates into more than $100 million in cost savings for the health care system in Maryland, with the largest savings coming from avoidance of urinary tract infections, septicemia and other severe infections, and pneumonia and other lung infections. If similar results could be achieved nationwide, the Medicare program would save an estimated $1.3 billion over 2 years, while the health care system as a whole would save $5.3 billion.

Hospitals have sanitation protocols regarding uniforms, equipment sterilization, washing, and other preventive measures. Thorough hand washing and/or use of alcohol rubs by all medical personnel before and after each patient contact is one of the most effective ways to combat nosocomial infections. More careful use of antimicrobial agents, such as antibiotics, is also considered vital.

Despite sanitation protocol, patients cannot be entirely isolated from infectious agents. Furthermore, patients are often prescribed antibiotics and other antimicrobial drugs to help treat illness; this may increase the selection pressure for the emergence of resistant strains.

Numerous studies have shown that improvements in drinking water and sanitation (WASH) lead to decreased risks of diarrhoea. Such improvements might include for example use of water filters, provision of high-quality piped water and sewer connections.

In institutions, communities, and households, interventions that promote hand washing with soap lead to significant reductions in the incidence of diarrhea. The same applies to preventing open defecation at a community-wide level and providing access to improved sanitation. This includes use of toilets and implementation of the entire sanitation chain connected to the toilets (collection, transport, disposal or reuse of human excreta).

The following types of diarrhea may indicate further investigation is needed:

- In infants

- Moderate or severe diarrhea in young children

- Associated with blood

- Continues for more than two days

- Associated non-cramping abdominal pain, fever, weight loss, etc.

- In travelers

- In food handlers, because of the potential to infect others;

- In institutions such as hospitals, child care centers, or geriatric and convalescent homes.

A severity score is used to aid diagnosis in children.

Diagnosis may be simple in cases where the patient's signs and symptoms are idiopathic to a specific cause. However this is generally not the case, considering that many pathogens which cause enteritis may exhibit the similar symptoms, especially early in the disease. In particular, "campylobacter, shigella, salmonella" and many other bacteria induce acute self-limited colitis, an inflammation of the lining of the colon which appears similar under the microscope.

A medical history, physical examination and tests such as blood counts, stool cultures, CT scans, MRIs, PCRs, colonoscopies and upper endoscopies may be used in order to perform a differential diagnosis. A biopsy may be required to obtain a sample for histopathology.

Mild cases usually do not require treatment and will go away after a few days in healthy people. In cases where symptoms persist or when it is more severe, specific treatments based on the initial cause may be required.

In cases where diarrhoea is present, replenishing fluids lost is recommended, and in cases with prolonged or severe diarrhoea which persists, intravenous rehydration therapy or antibiotics may be required. A simple oral rehydration therapy (ORS) can be made by dissolving one teaspoon of salt, eight teaspoons of sugar and the juice of an orange into one litre of clean water. Studies have shown the efficacy of antibiotics in reducing the duration of the symptoms of infectious enteritis of bacterial origin, however antibiotic treatments are usually not required due to the self-limiting duration of infectious enteritis.

Globally, infants are a population that are especially vulnerable to foodborne disease. The World Health Organization has issued recommendations for the preparation, use and storage of prepared formulas. Breastfeeding remains the best preventative measure for protection of foodborne infections in infants.

Food may be contaminated during all stages of food production and retailing. In order to prevent viral contamination, regulatory authorities in Europe have enacted several measures:

- European Commission Regulation (EC) No 2073/2005 of November 15, 2005

- European Committee for Standardization (CEN): Standard method for the detection of norovirus and hepatitis A virus in food products (shellfish, fruits and vegetables, surfaces and bottled water)

- CODEX Committee on Food Hygiene (CCFH): Guideline for the application of general principles of food hygiene for the control of viruses in food

The diagnosis of Gianotti–Crosti syndrome is clinical. A validated diagnostic criteria is as follows:

A patient is diagnosed as having Gianotti–Crosti syndrome if:

1. On at least one occasion or clinical encounter, he/she exhibits all the positive clinical features,

2. On all occasions or clinical encounters related to the rash, he/she does not exhibit any of the negative clinical features,

3. None of the differential diagnoses is considered to be more likely than Gianotti–Crosti syndrome on clinical judgment, and

4. If lesional biopsy is performed, the histopathological findings are consistent with Gianotti–Crosti syndrome.

The positive clinical features are:

- Monomorphous, flat-topped, pink-brown papules or papulovesicles 1-10mm in diameter.

- At least three of the following four sites involved – (1) cheeks, (2) buttocks, (3) extensor surfaces of forearms, and (4) extensor surfaces of legs.

- Being symmetrical, and

- Lasting for at least ten days.

The negative clinical features are:

- Extensive truncal lesions, and

- Scaly lesions.

There is debate as to the benefits of screening. Some studies suggest that early detection would decrease the risk of osteoporosis and anaemia. In contrast, a cohort study suggested that people with undetected coeliac disease had a beneficial risk profile for cardiovascular disease (less overweight, lower cholesterol levels). There is limited evidence that screen-detected cases benefit from a diagnosis in terms of morbidity and mortality; hence, population-level screening is not presently thought to be beneficial.

The United States Preventive Services Task Force found insufficient evidence to make a recommendation among those without symptoms. In the United Kingdom, the National Institute for Health and Clinical Excellence (NICE) recommends testing for coeliac disease in people with newly diagnosed chronic fatigue syndrome and irritable bowel syndrome, as well as in type 1 diabetics, especially those with insufficient weight gain or unexplained weight loss. It is also recommended in autoimmune thyroid disease, dermatitis herpetiformis, and in the first-degree relatives of those with confirmed coeliac disease.

Serology has been proposed as a screening measure, because the presence of antibodies would detect some previously undiagnosed cases of coeliac disease and prevent its complications in those people. However, serologic tests have high sensitivity only in people with total villous atrophy and have very low ability to detect cases with partial villous atrophy or minor intestinal lesions. Testing for coeliac disease may be offered to those with commonly associated conditions.

The differential diagnoses are: acrodermatitis enteropathica, erythema infectiosum, erythema multiforme, hand-foot-and-mouth disease, Henoch–Schönlein purpura, Kawasaki disease, lichen planus, papular urticaria, papular purpuric gloves and socks syndrome, and scabies.