Gastroenteritis
Gastroenteritis is an inflammation of the stomach and the intestines. More commonly, gastroenteritis is called the stomach flu.
The symptoms of gastroenteritis always include diarrhea. Fever, and vomiting can also be present. Typically the symptoms associated with a bout of gastroenteritis typically last only several days and are self-limiting. But sometimes the malady can be more extended.
The diarrhea in gastroenteritis is very loose, even watery. Also, bowel movements are frequent, occurring even several times an hour as the body attempts to expel the offending microorganism. This large loss of fluid creates the potential for dehydration. Usually dehydration is not an issue in an adult, unless the person is incapable of caring for themselves and has no other caregiver. Dehydration is an important issue in children. If a child is hospitalized because of diarrhea, it is usually because of complications arising from dehydration, rather than from the actual stomach and intestinal infection.
The other symptoms of gastroenteritis are especially complicating in children. Vomiting makes it difficult to administer drugs to combat a bacterial infection. Also, the loss of stomach contents can exacerbate dehydration.
Gastroenteritis-induced diarrhea is one of the major causes of death in infants around the world. In Asia, Africa, and Latin America millions of deaths in the newborn to four years age group occurs every year.
Gastroenteritis can be caused by viruses and bacteria. Viruses are the more common cause. Many There types of viruses can cause gastroenteritis. These include rotaviruses, enteroviruses, adenoviruses, caliciviruses, astroviruses, Norwalk virus and a group of Norwalk-like viruses. Of these, rotavirus infections are the most common.
Viral gastroenteritis tends to appear quickly, within three days of ingestion of the virus, and diminishes within a week. Those whose immune system is compromised may experience symptoms for a longer period of time.
Rotavirus is a virus that contains ribonucleic acid as the genetic material. The genetic material is enclosed within a double shell of protein. The virus is a member of the Reoviridae family of viruses. There are three main groups of rotavirus with respect to the antibodies that are produced against them. These types are called groups A, B, and C. Group A rotavirus is the cause of more than three million cases of gastroenteritis in the United States every year. The group B rotavirus causes diarrhea in adults, and has been the cause a several major outbreaks of severe diarrhea in China. Finally, the group C rotavirus can cause diarrhea in both children and adults, but is encountered much less frequently than groups A and B.
Rotavirus gastroenteritis is very contagious, spreading from person to person in a fecal to oral route. Not surprisingly, the virus is frequently encountered in day care facilities, where the care of the soiled diapers of infants occurs regularly. Improper hygiene, especially hand washing, contributes directly to the spread of the virus. Infected individuals can shed large numbers of virus in their diarrhea. Infection can also be spread by the contamination of eating utensils. Food can become contaminated if the food handler has not properly washed their hands after using the bathroom. Shellfish can also be a source of the virus. Because shellfish feed by filtering water through a special filter feeding apparatus, virus in the water can become trapped and concentrated inside the shellfish. Eating the shellfish, especially raw, spreads the virus.
Gastroenteritis due to the Norwalk virus tends to be more common in adults. However, more advanced immunological methods of detection have detected antibody to the virus in many children. Thus, children may be infected by the virus but show no symptoms. Infection in the adult years produces gastroenteritis, for reasons that are as yet unknown. Discovering the nature of the asymptomatic response of children could led to a therapeutic strategy for the adult infection.
Bacteria also cause gastroenteritis. The bacteria of concern include certain strains of Escherichia coli, Salmonella, Shigella, and Vibrio cholerae. In developed countries, where sanitary conditions and water treatment are established, bacterial gastroenteritis is infrequent. But the bacterial form remains problematic in the under-developed world, where water is more vulnerable to contamination. Bacterial gastroenteritis can also be caused by the ingestion of contaminated food. For example the presence of Salmonella in potato salad that has been improperly stored or of E.coli O157:H7 in undercooked meat can cause the malady.
The protozoan Cryptosporidium parvum also causes gastroenteritis following the ingestion of contaminated water.
The bacterial and protozoan cases of gastroenteritis account for well below half of the reported cases. The majority of cases are of viral origin.
In the treatment of gastroenteritis it is important to establish whether the source of the condition is bacterial, viral, protozoan or another and non-biological factor. Intolerance to the digestion of the lactose constituent of milk can also cause gastroenteritis, for example. The need to establish the origin of the malady is important, since bacterial infections will respond to the administration of antibiotics while viral infections will not. Furthermore, the use of antibiotics in a viral infection can actually exacerbate the diarrhea.
In August 1998, a vaccine for rotavirus gastroenteritis was licensed for sale in the United States. From September 1998 until July 1999, 15 cases of intussusception (a condition where a segment of bowel folds inside an adjacent segment, causing an obstruction) were reported among infants who received the vaccine. Subsequently, the vaccine was withdrawn from the market. No other vaccine has as yet been licensed for use.