Inflammatory Bowel Disease

Inflammatory bowel disease is a collection of inflammatory conditions primarily affecting the intestines. The two principal inflammatory bowel diseases are Crohn’s disease and ulcerative colitis. Unlike Crohn’s disease, which may affect any part of the GI tract and the joints as well as the skin, ulcerative colitis mainly affects just the colon and rectum. Both diseases occur when the body’s own immune system attacks the digestive system. Both diseases also typically first appear in the late teens or early twenties and occur equally in all sexes and genders.

Diverticulitis

Diverticulitis is a digestive disease in which tiny pouches in the wall of the large intestine become infected and inflamed. Symptoms typically include lower abdominal pain of sudden onset. There may also be fever, nausea, diarrhea or constipation, and blood in the stool. Having large intestine pouches called diverticula (Figure 18.7.318.7.3) that are not inflamed is called diverticulosis. Diverticulosis is thought to be due to a combination of genetic and environmental factors and is more common in people who are obese. Infection and inflammation of the pouches (diverticulitis) occur in about 10 to 25 percent of people with diverticulosis and is more common at older ages. The infection is generally caused by bacteria.

Diverticulitis can usually be diagnosed with a CT scan. Mild diverticulitis may be treated with oral antibiotics and a short-term liquid diet. For severe cases, intravenous antibiotics, hospitalization, and complete bowel rest (no nourishment via the mouth) may be recommended. Complications such as abscess formation or perforation of the colon require surgery.

Peptic Ulcer

A peptic ulcer is a sore in the lining of the stomach or the duodenum (the first part of the small intestine). If the ulcer occurs in the stomach, it is called a gastric ulcer; if it occurs in the duodenum, it is called a duodenal ulcer. The most common symptoms of peptic ulcers are upper abdominal pain that often occurs at night and improves with eating. Other symptoms may include belching, vomiting, weight loss, and poor appetite. However, many people with peptic ulcers, particularly older people, have no symptoms. Peptic ulcers are relatively common, with about 10 percent of people developing a peptic ulcer at some point in their life.

The most common cause of peptic ulcers is infection with the bacterium Helicobacter pylori, which may be transmitted by food, contaminated water, or human saliva (for example, by kissing or sharing eating utensils). Surprisingly, the bacterial cause of peptic ulcers was not discovered until the 1980s. The scientists who made the discovery are Australians Robin Warren and Barry J. Marshall. Although the two scientists eventually won a Nobel Prize for their discovery, their hypothesis was poorly received at first. To demonstrate the validity of their discovery, Marshall used himself in an experiment. He drank a culture of bacteria from a peptic ulcer patient and developed symptoms of peptic ulcer in a matter of days. His symptoms resolved on their own within a couple of weeks, but he took antibiotics to kill any remaining bacteria at his wife’s urging (apparently because bad breath is also one of the symptoms of H. pylori infection). Marshall’s self-experiment was published in the Australian Medical Journal and is among the most cited articles ever published in the journal.

Another relatively common cause of peptic ulcers is the chronic use of non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin or ibuprofen. Additional contributing factors may include tobacco smoking and stress, although these factors have not been demonstrated conclusively to cause peptic ulcers independent of H. pylori infection. Contrary to popular belief, diet does not appear to play a role in either causing or preventing peptic ulcers. Eating spicy foods and drinking coffee and alcohol were once thought to cause peptic ulcers. These lifestyle choices are no longer thought to have much if any effect on the development of peptic ulcers.

Peptic ulcers are typically diagnosed on the basis of symptoms or the presence of H. pylori in the GI tract. However, endoscopy (Figure 18.7.518.7.5), which allows direct visualization of the stomach and duodenum with a camera, may be required for a definitive diagnosis. Peptic ulcers are usually treated with antibiotics to kill H. pylori, along with medications to temporarily decrease stomach acid and aid in healing. Unfortunately, H. pylori have developed resistance to commonly used antibiotics, so treatment is not always effective. If a peptic ulcer has penetrated so deep into the tissues that it causes perforation of the wall of the stomach or duodenum, then emergency surgery is needed to repair the damage.

Gastroenteritis

Gastroenteritis, also known as infectious diarrhea, is an acute and usually self-limiting infection of the GI tract by pathogens. Symptoms typically include some combination of diarrhea, vomiting, and abdominal pain. Fever, lack of energy, and dehydration may also occur. The illness generally lasts less than two weeks, even without treatment, but in young children, it is potentially deadly. Gastroenteritis is very common, especially in poorer nations. Worldwide, up to five billion cases occur each year, resulting in about 1.4 million deaths. In the United States, infectious diarrhea is the second most common type of infection after the common cold.

Commonly called “stomach flu,” gastroenteritis is unrelated to the influenza virus, although viruses are the most common cause of the disease (Figure 18.7.618.7.6). In children, rotavirus is most often the cause, whereas norovirus is more likely to be the cause in adults. Besides viruses, other potential causes of gastroenteritis include fungi, protozoa (including Giardia lamblia, described below), and bacteria (most often Escherichia coli or Campylobacter jejuni). Transmission of pathogens may occur due to eating improperly prepared foods or foods left to stand at room temperature, drinking contaminated water, or having close contact with an infected individual.

Gastroenteritis is less common in adults than children, partly because adults have acquired immunity after repeated exposure to the most common infectious agents. Adults also tend to have better hygiene than children. If children have frequently repeated incidents of gastroenteritis, they may suffer from malnutrition, stunted growth, and developmental delays. Many cases of gastroenteritis in children can be avoided by giving them a rotavirus vaccine. Frequent and thorough hand washing can cut down on infections caused by other pathogens.

Treatment of gastroenteritis generally involves increasing fluid intake to replace fluids lost in vomitus or diarrhea. Oral rehydration solution, which is a combination of water, salts, and sugar, is often recommended. In severe cases, intravenous fluids may be needed. Antibiotics are not usually prescribed because they are ineffective against viruses that cause most cases of gastroenteritis.

Giardiasis

Giardiasis, popularly known as beaver fever, is a type of gastroenteritis caused by a GI tract parasite, the single-celled protozoan Giardia lamblia (Figure 18.7.718.7.7). The parasite inhabits the digestive tract of a wide variety of domestic and wild animal species in addition to human beings, including cows, rodents, and sheep as well as beavers (hence its popular name). Giardiasis is one of the most common parasitic infections in people the world over, with hundreds of millions of people infected worldwide each year.

Transmission of G. lamblia is via a fecal-oral route. Those at greatest risk include travelers to countries where giardiasis is common, people who work in child-care settings, backpackers and campers who drink untreated water from lakes or rivers, and people who have close contact with infected people or animals in other settings. In the United States, giardiasis occurs more often during the summer than other seasons, probably because people spend more time outdoors and in wild settings at that time of year.

Symptoms of giardiasis can vary widely. About a third of people with the infection have no symptoms, whereas others have severe diarrhea with poor absorption of nutrients. Problems with absorption occur because the parasites inhibit intestinal digestive enzyme production, cause detrimental changes in microvilli lining the small intestine, and kill off small intestinal epithelial cells. The illness can result in weakness, loss of appetite, stomach cramps, vomiting, and excessive gas. Without treatment, symptoms may continue for several weeks. Treatment with an antibiotic may be needed if symptoms persist longer or are particularly severe.