Acute Viral Gastroenteritis

Acute gastroenteritis is a common cause of morbidity and mortality worldwide. Conservative estimates put diarrhea in the top 5 causes of deaths worldwide, with most occurring in young children in nonindustrialized countries. In industrialized countries, diarrheal diseases are a significant cause for morbidity across all age groups.

Causes include bacteria, viruses, parasites, toxins, and drugs. Viruses are responsible for a significant percentage of cases affecting patients of all ages. Viral gastroenteritis ranges from a self-limited watery diarrheal illness (usually <1 wk) associated with symptoms of nausea, vomiting, anorexia, malaise, or fever, to severe dehydration resulting in hospitalization or even death:-

• The clinician encounters acute viral gastroenteritis in 3 settings. The first is sporadic gastroenteritis in infants, which most frequently is caused by rotavirus.
• The second is epidemic gastroenteritis, which occurs either in semiclosed communities (eg, families, institutions, ships, vacation spots) or as a result of classic food-borne or water-borne pathogens.
• The third is sporadic acute gastroenteritis of adults, which most likely is caused by caliciviruses, rotaviruses, astroviruses, or adenoviruses.

Causes of Sporadic infantile viral gastroenteritis

• Group A rotavirus causes 25-65% of severe infantile gastroenteritis worldwide.
• After rotavirus, the most important cause of acute infantile gastroenteritis probably is calicivirus infection. Using broadly reactive reverse-transcription polymerase chain reaction for calicivirus to study stool specimens from children with acute gastroenteritis, studies have found these viruses in 7-22% of cases.
• Astrovirus infection is associated with 2-9% of cases of infantile gastroenteritis worldwide, making it the third most frequent cause after rotavirus and calicivirus.
• Studies confirm that they cause 2-6% of cases.

Epidemic viral gastroenteritis

• Most cases of epidemic viral gastroenteritis in adults and children are caused by the caliciviruses. Some examples include Norovirus (formerly called Norwalk-like viruses), genogroup I (eg, Norwalk, Southampton, Desert Shield, Cruise Ship); Norovirus (formerly Norwalk-like viruses), genogroup II (eg, Snow Mountain, Mexico, White River, Lordsdale, Bristol, Camberwell, Toronto, Hawaii, Melksham); and Sapovirus (formerly Sapporo-like viruses), which sometimes are referred to as genogroup III, although they are not like Norwalk (eg, Sapporo, Parkville, Manchester, Houston, London).
• Modern molecular diagnostic techniques, such as broadly reactive reverse-transcription polymerase chain reaction, have linked these viruses to epidemics associated with oysters, contaminated community water supplies, restaurant food, hospital patients and staff, day care facilities, nursing homes, college dormitories, military ships, cruise ships, and vacation spots.
• Rotavirus and astrovirus also may cause epidemics of viral gastroenteritis.
• Some viruses, like noroviruses, may be transmitted by an airborne route.
• Rotaviruses attach and enter mature enterocytes at the tips of small intestinal villi.

The current knowledge on the mechanisms leading to diarrheal disease by rotavirus is as follows:

• Rotavirus infections induce maldigestion of carbohydrates, and their accumulation in the intestinal lumen, as well as a malabsorption of nutrients and a concomitant inhibition of water reabsorption, can lead to a malabsorption component of diarrhea.
• Rotavirus secretes an enterotoxin, NSP4, which leads to a Ca2+ -dependent Cl- secretory mechanism.  Mobilization of intracellular calcium associated with NSP4 expressed endogenously or added exogenously is known to induce transient chloride secretion.
• Morphologic abnormalities can be minimal, and studies demonstrate that rotavirus can be released from infected epithelial cells without destroying them.
• Viral attachment and entry into the epithelial cell without cell death may be enough to initiate diarrhea. The epithelial cell synthesizes and secretes numerous cytokines and chemokines, which can direct the host immune response and potentially regulate cell morphology and function.
• Studies also suggest that one of the nonstructural viral proteins may act as an enterotoxin, promoting active chloride secretion mediated through increases in intracellular calcium concentration. Toxin-mediated diarrhea would explain the observation that villus injury is not necessarily linked to diarrhea.

The physical examination can be helpful in determining the etiology of gastroenteritis and in assessing the presence and degree of dehydration.

• Temperature, blood pressure and pulse, and body weight can provide evidence of severity of the condition.
• Temperature may be slightly elevated. High fever suggests bacterial infection. Tachycardia, thready pulse, and hypotension suggest severe dehydration.
• The degree of weight loss may be related to dehydration and the duration of the diarrhea.
• The mucous membranes and the skin should be examined carefully. Dry mouth, no tears, skin tenting, dry skin, and capillary refill are all signs of dehydration.
• The mental status in elderly patients and infants may be abnormal, especially when blood pressure and circulation are compromised.
• The abdominal examination may demonstrate mild tenderness. Severe abdominal pain and tenderness suggest bacterial infection or an abdominal emergency.

Novel Imaging Technique to Measure Capillary-Refill Time

A study was done by Itai Shavit, MDa, Rollin Brant, PhDb, Cheri Nijssen-Jordan, MDa, Roger Galbraith, MDa and David W. Johnson, MD

A Novel Imaging Technique to Measure Capillary-Refill Time: Improving Diagnostic Accuracy for Dehydration in Young Children With Gastroenteritis

OBJECTIVE

Assessment of dehydration in young children currently depends on clinical judgment, which is relatively inaccurate. The goal is to determine whether digitally measured capillary-refill time assesses the presence of significant dehydration (5%) in young children with gastroenteritis more accurately than conventional capillary refill and overall clinical assessment.

METHODS

Children were enrolled with gastroenteritis,1 month to 5 years of age, who were evaluated in a tertiary-care pediatric emergency department and judged by a triage nurse to be at least mildly dehydrated. Before any treatment, the weight was measured and digitally measured capillary-refill time of these children. Pediatric emergency physicians determined capillary-refill time by using conventional methods and degree of dehydration by overall clinical assessment by using a 7-point Likert scale. Postillness weight gain was used to estimate fluid deficit; beginning 48 hours after assessment, children were reweighed every 24 hours until 2 sequential weights differed by no more than 2%. The accuracy of digitally measured capillary-refill time was compared with conventional capillary refill and overall clinical assessment by determining sensitivities, specificities, likelihood ratios, and area under the receiver operator characteristic curves.

RESULTS

A total of 83 patients were enrolled and had complete follow-up; 13 of these patients had significant dehydration (5% of body weight). The area under the receiver operator characteristic curves for digitally measured capillary-refill time and overall clinical assessment relative to fluid deficit (<5% vs 5%) were 0.99 and 0.88, respectively. Positive likelihood ratios were 11.7 for digitally measured capillary-refill time, 4.5 for conventional capillary refill, and 4.1 for overall clinical assessment.

CONCLUSIONS

Results of this prospective cohort study suggest that digitally measured capillary-refill time more accurately predicts significant dehydration (5%) in young children with gastroenteritis than overall clinical assessment.

Probiotics and the Treatment of Infectious Diarrhea: Viral Diarrhea

Probiotics and the Treatment of Infectious Diarrhea: Viral Diarrhea

The effect of probiotics on shortening episodes of acute infectious
diarrhea has been well-documented. Enterococcus faecium ,
Streptococcus faecium SF68 and certain lactobacillus strains have
proven efficacy. A metaanalysis of previously published randomized,
controlled studies of lactobacillus therapy reveals that the duration
of diarrhea in hospitalized children is shortened by an average of 0.7
days. Similarly a randomized, placebo-controlled trial in a cohort of
nonhospitalized children attending day-care centers also reduced the
mean duration of diarrhea. The underlying mechanism by which
probiotics produce their clinical effect is likely multifactorial and
has led to much speculation. Some theorize that lactobacilli enhance
the expression and elaboration of intestinal mucins. These
glycoproteins appear to be protective during intestinal infections.
However, protective qualities may be overcome by mucinase-producing
bacteria. Others hypothesize that rotavirus causes biphasic diarrhea,
the first osmotic and the second due to overgrowth of urease-producing
bacteria; probiotics prevent bacterial overgrowth.

In studies of the immunomodulating effects of probiotics, 49 children
with acute rotavirus diarrhea were randomized to receive Lactobacillus
GG (LGG), Lactobacillus casei subsp. rhamnosus ( Lactophilus ) or a
combination of Streptococcus thermophilus and Lactobacillus delbruckii
(Yalacta). Mean duration of diarrhea was 1.8 days for children in the
LGG group, 2.8 in the Lactophilus group and 2.6 in the Yalacta group.
Only LGG significantly increased the number of rotavirus-specific
IgA-secreting cells and serum IgA level in the convalescent stage.
This and similar studies suggest that the humoral immune system is
significant in the effect of probiotics. However, enhanced humoral
response does not fully explain the clinical effect of probiotics as
evidenced by a study comparing the efficacy of heat-inactivated LGG
against viable bacteria in the treatment of rotaviral diarrhea.
Reduction in the duration of diarrhea was the same for both groups,
but significantly fewer infants receiving the heat-inactivated strains
had detectable IgA responses.

Inflammatory Bowel Disease

The digestive system is a set of organs (including the stomach, large and small intestines, rectum, and others) that convert the foods we eat into nutrients and absorb these nutrients into the bloodstream to fuel our bodies. We seldom notice its workings unless something goes wrong, as in the case of inflammatory bowel disease (IBD).

It's estimated that up to 1 million Americans have inflammatory bowel disease. It occurs most frequently in people ages 15 to 30, but it can also affect younger children and older people. And there are significantly more reported cases in western Europe and North America than in other parts of the world.

What Is Inflammatory Bowel Disease?

Inflammatory bowel disease (which is not the same thing as irritable bowel syndrome, or IBS) refers to two chronic diseases that cause inflammation of the intestines: ulcerative colitis and Crohn's diseaseCrohn's disease. Although the diseases have some features in common, there are some important differences.

Ulcerative colitis is an inflammatory disease of the large intestine, also called the colon. In ulcerative colitis, the inner lining - or mucosa - of the intestine becomes inflamed (meaning the lining of the intestinal wall reddens and swells) and develops ulcers (an ulcer is a sore, which means it's an open, painful wound). Ulcerative colitis is often the most severe in the rectal area, which can cause frequent diarrhea. Mucus and blood often appear in the stool (feces or poop) if the lining of the colon is damaged.

Crohn's disease differs from ulcerative colitis in the areas of the bowel it involves - it most commonly affects the last part of the small intestine (called the terminal ileum) and parts of the large intestine. However, Crohn's disease isn't limited to these areas and can attack any part of the digestive tract. Crohn's disease causes inflammation that extends much deeper into the layers of the intestinal wall than ulcerative colitis does. Crohn's disease generally tends to involve the entire bowel wall, whereas ulcerative colitis affects only the lining of the bowel.

What Causes It?

Medical research hasn't determined yet what causes inflammatory bowel disease. But researchers believe that a number of factors may be involved, such as the environment, diet, and possibly genetics.

Current evidence suggests that there's likely a genetic defect that affects how our immune system works and how the inflammation is turned on and off in those people with inflammatory bowel disease, in response to an offending agent, like bacteria, a virus, or a protein in food.

The problem in people with the disease is that the inflammation gets turned on, but it doesn't get turned off. Medical evidence also indicates that smoking may enhance the likelihood of developing Crohn's disease.

What Are the Signs and Symptoms?

The most common symptoms of both ulcerative colitis and Crohn's disease are diarrhea and abdominal pain. Diarrhea can range from mild to severe (as many as 20 or more trips to the bathroom a day). If the diarrhea is extreme, it can lead to dehydration, rapid heartbeat, and a drop in blood pressure. And continued loss of small amounts of blood in the stool can lead to anemia.

At times, those with inflammatory bowel disease may also have constipation. With Crohn's disease, this can happen as a result of a partial obstruction (called stricture) in the intestines. In ulcerative colitis, constipation may be a symptom of inflammation of the rectum (also known as proctitis).

Because of the loss of fluid and nutrients from diarrhea and chronic inflammation of the bowel, someone with inflammatory bowel disease may also experience fever, fatigue, weight loss, dehydration, and malnutrition. Pain usually results from the abdominal cramping, which is caused by irritation of the nerves and muscles that control intestinal contractions.

But inflammatory bowel disease can cause other health problems that occur outside the digestive system. Although medical researchers don't know why these complications happen, some people with the disease may show signs of inflammation elsewhere in the body, such as in the joints, eyes, skin, and liver. Skin tags that look like hemorrhoids or abscesses may also develop around the anus.

Inflammatory bowel disease may also cause a delay in puberty or growth problems for some kids and teens with the condition, because it can interfere with a person getting nutrients from the foods he or she eats.

How Is It Diagnosed?

Inflammatory bowel disease can be hard to diagnose because there may be no symptoms, even if the person's bowel has become increasingly damaged for years. Once symptoms do appear, they often resemble those of other conditions, which may make it difficult for doctors to diagnose.

If your child has any of the symptoms of the disease, it's important to see your child's doctor. In addition to doing a physical examination, the doctor will ask you and your child about any concerns and symptoms your child has, your child's past health, your family's health, any medications your child is taking, any allergies your child may have, and other issues. This is called the medical history.

After hearing your child's symptoms, if the doctor suspects inflammatory bowel disease, he or she may suggest certain tests. Blood tests may be done to determine if there are signs of inflammation in your child's body, which are often present with the disease. The doctor may also check for anemia and for other causes of your symptoms, like infection.

The doctor will examine your child's stool for the presence of blood. He or she may look at your child's colon with an instrument called an endoscope. Also called a colonoscope or coloscope, this instrument is a long, thin tube inserted through the anus and attached to a TV monitor. This procedure is called a colonoscopy, which allows the doctor to see inflammation, bleeding, or ulcers on the wall of your child's colon.

The doctor may also do a test called an upper endoscopy to check the esophagus, stomach, and upper small intestine for inflammation, bleeding, or ulcers. During the exam, the doctor may perform a biopsy, which involves taking a small sample of tissue from part of the colon so it can be viewed with a microscope or sent to a laboratory for other kinds of analysis.

A doctor may also order a barium study of the intestines. This procedure involves drinking a thick white solution called barium, which shows up white on an X-ray film, allowing a doctor to get a better look at what's going on in a person's intestines.

How Is It Treated?

Drug treatment is the main method for relieving the symptoms of both ulcerative colitis and Crohn's disease. Great progress is being made in the development of medications for treating inflammatory bowel disease. Your child's doctor may prescribe:

anti-inflammatory drugs (used to decrease the inflammation caused by the disease)
immunosuppressive agents (which work to restrain the immune system from attacking the body's own tissues and causing further inflammation)

If a child with inflammatory bowel disease doesn't respond to either of these medicines, your child's doctor may suggest surgery. But surgical procedures for ulcerative colitis and Crohn's disease are quite different.

With Crohn's disease, doctors make every attempt to avoid surgery because of the recurring nature of the disease. There's also a concern that an aggressive surgical approach to Crohn's disease will cause further complications, such as short bowel syndrome (which involves growth failure and a reduced ability to absorb nutrients).

In the case of ulcerative colitis, removal of the colon (large intestine) may be necessary, along with a surgical procedure called an ileoanal anastomosis (also called an ileoanal pull-through) in which doctors form a pouch from the small bowel to collect stool in the pelvis. This allows the stool to pass through the anus.

Diarrhea - Advice

Of the childhood diseases parents must deal with, diarrhea is one of the least pleasant, especially with a child in diapers. Unfortunately, it is among the most common. With an understanding of the mechanisms of diarrhea and the appropriate treatment, we can minimize our children's discomfort and our own custodial chores.

Diarrhea, defined as both frequent and watery stools, is most often caused by a gastro-intestinal viral infection. Certainly there are other causes, including bacterial infections, parasitic infections, food intolerance, food allergies, bowel functional problems and other inflammatory conditions. The viral, bacterial and parasitic forms are contagious, which is why, just as in other infectious diseases, good hand-washing, particularly after using sanitary facilities, is imperative.

Associated symptoms, such as persistent fever, prolonged diarrhea (over 7 days despite proper therapy) and weight loss, are suggestive of a process other than simple viral diarrhea. Bacterial and parasitic infections require specific laboratory testing and prescription therapy. Although food intolerance, food allergies, bowel functional problems (e.g., Irritable Bowel Syndrome and constipation) and inflammatory conditions (regional enteritis and ulcerative colitis) are often associated with diarrhea, these specific medical conditions require specialized therapy that is individualized to the patient by their personal physician. That management is beyond the scope of this article. Any suspicion that these conditions are present should trigger a visit to the child's doctor.

The viruses that cause gastrointestinal upset are typically acquired directly from another human. These viruses enter the body through the mouth, eyes or nose either by respiratory secretions or from touching the face with unclean hands. Recent reports have identified the water supply on some cruise ships as a source of outbreaks of shipboard diarrhea. Fever and cold symptoms are commonly associated with these infections. This differs from parasitic infections, which are devoid of cold symptoms and fever, or bacterial infections, which may be associated with fever, but not cold symptoms. Bloody loose stools are otherwise more suggestive or non-viral causes of the diarrhea. Of note is that cancer is almost never a cause of bloody stools in children. Bacterial, parasitic, inflammatory and mechanical causes (constipation or benign polyps) are the things that should come to mind first.

Bacterial enteritis is acquired by ingestion of contaminated food or water. Responsibility for outbreaks of certain enteral bacterial infections has been attributed to nearly every food group from salad and milk products to meat and vegetables, especially when stored or washed improperly. Whether here or abroad, be sure your restaurant food is served and eaten while hot and freshly cooked and avoid partaking of food from curbside vendors (even in the U.S.) because of the uncertainty of the cart heating unit being able to maintain temperature of the food at a level that kills bacteria. Poultry, especially chicken eggs and turkey, are known common carriers of salmonella. Some authorities recommend not rinsing the Thanksgiving turkey before cooking it, since you would risk splashing salmonella all over the food preparation area. Hand washing after handling chicken egg shells (or after handling pet amphibians) will also help avoid contamination. Avoid raw egg products (some Caesar salad dressings). Typhoid vaccine is available for prevention of salmonella infections in travelers to countries where this infection is prevalent.

Travelers to developing countries and campers are at increased risk for parasitic, as well as bacterial, intestinal infections. In countries that do not have sanitary drinking water supply systems (especially common in rural areas), waste water may contaminate drinking water. In these situations, it is best to drink only commercially bottled carbonated beverages or water. Campers may wish to carry iodine pills to sanitize ground water for drinking. Alternatively and more effectively, camping suppliers can provide small portable water pumps, which filter out all infectious organisms. Vigorous boiling for one minute eliminates parasitic and bacterial organisms, but may not kill all viruses.

The mainstay of management of viral diarrhea is dietary. Fluid replacement is critical, especially in the young infant. There is no fluid that particularly stops diarrhea, but there are liquids that will not exacerbate it. Electrolyte solutions, such as Pedialyte®, Lytren®, Kaolectrolyte® and Gerber Liquilytes Oral Maintenance Solution® are all appropriate, either in liquid or freeze push-pop form, depending on the age of the child. Older children with diarrhea often resort to sports drinks, such as Gatorade® or Powerade® for their fluid and electrolyte replacement. Although supported by some studies, fruit juice is usually not recommended in this situation because it tends to be laxative. Cow milk products are not recommended because of four factors:

The dissolved mineral content (solute load) causes an obligatory urinary fluid loss which may compromise the child's fluid balance further
Cow milk sugar, called lactose, is difficult to digest in the presence of a viral enteritis because the necessary enzyme, lactase, is not being produced during and after the illness (Cow milk products should be avoided for at least three days or longer after a viral intestinal insult)
Cow milk protein may not be well digested in the presence of a viral enteritis
Conventional belief holds that nasopharyngeal mucus becomes thicker after ingestion of milk (there is currently no solid scientific evidence to prove or disprove this supposition)

Occasionally, rice or soy beverages are recommended for children who need an enhanced calorie intake or who refuse other liquids. When the child exhibits a desire to eat solid foods, the usual initial offerings consist of foods that are naturally constipating: Bananas, Rice, Apples and Toast (called the BRAT diet). Fruits other than bananas and apples are laxative. Toast represents starchy foods, such as bread, cake, cracker, pasta, potatoes, etc. Vegetables and meats are neither harmful during diarrhea nor helpful in making the stool quality less uncomfortable.

In the occasional child whose diarrhea is very frequent and very watery, a plant extract called attapulgite, sold under the names of Kaopectate® and Diasorb®, will help make the stool less frequent and less watery. (These brands also market a product containing bismuth subsalicylate. We do NOT recommend these for children.) Attapulgite is not absorbed and there is no toxicity associated with it. The same brands, however, market other ingredients under similar brand names, so care should be taken to read the label before administering these preparations to a child. Note that these preparations do not cure an intestinal viral illness. Only time and supportive care can accomplish this goal. We do not recommend agents that inhibit intestinal motility (e.g., Lomotil®, paragoric or Immodium®) to treat viral diarrhea. These agents can make a child more lethargic and lead to accumulation of the diarrhea in the intestine, which allows enhanced absorption of bacterial toxins. They appear to work only by hiding the diarrhea from the child's caretaker. Custodial care of the infant in this situation includes prevention of diaper rash by application of a topical diaper rash cream (e.g., Desitin®, A and D Ointment®, Diaperene®, J&J Ointment®, Balmex®, etc.).

If any of the warning signs mentioned in this article appear during the course of your child's diarrhea, you should consult with your child's doctor. In uncomplicated viral diarrhea, as long as you administer adequate fluid intake, the process will eventually end.