January 1997
NEW YORK — Anyone who reads a daily newspaper knows that diarrheal outbreaks are common and are on the rise. However, there are steps you can take to protect your patients. Larry K. Pickering, MD, reviewed these media stars during his keynote address at the Ninth Annual Infectious Diseases in Children Symposium here.
In the United States, there are 25 million to 40 million episodes of diarrhea yearly, resulting in 220,000 hospitalizations and from 150 to 400 deaths. Each year, there are about 3 million office visits because of diarrheal disease, according to Pickering, professor of pediatrics at the Eastern Virginia Medical School and director of the Center for Pediatric Research at Children's Hospital of The King's Daughters in Norfolk, Va.
Worldwide, the numbers are even more staggering — from 3 million to 5 million deaths occur each year from diarrhea, making it the second leading killer.
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Last year, for instance, the Minnesota Department of Health reported an outbreak of Salmonella enteritidis Gastroenteritis developed in about 224,000 people who ate ice cream. The ice cream premix was contaminated during shipping when it was placed in a tanker truck that had previously carried raw eggs.
Another example occurred around Thanksgiving. The Department of Agriculture recommended that people use a meat thermometer to make sure that turkey stuffing reaches an internal temperature of 165° to kill Salmonella, which is common in U.S. poultry and eggs.
Age and debilitating physical conditions are the most common factors for severe infection. Immunocompetent individuals usually do not become severely ill. However, the story is different for the very old, the very young and the immunocompromised. Any pediatrician who is treating an immunocompromised child should talk to parents about how to handle and prepare food to prevent infection.
Like other bacteria, Salmonella is developing resistance. In 1979 to 1980, about 18% were resistant to one antimicrobial agent and about 12% were resistant to three or more antimicrobials. Ten years later, 30% of Salmonella were resistant to one antibiotic and about 26% were multidrug resistant.
One reason for Salmonella resistance is that antibiotics were introduced into poultry feed, increasing the propensity for resistance, he explained. Pediatricians should check for susceptibilities of all Salmonella organisms, if the disease caused by these organisms needs treatment.
Therapy generally is not recommended for acute gastroenteritis, unless the illness is severe or the child has an underlying immune deficiency.
Last July, Japan wrestled with an epidemic of Escherichia coli O157:H7 that sickened more than 8,000 people and resulted in seven deaths. E. coli O157:H7 outbreaks are common in the United States, too.
Last fall, an outbreak in the West caused 61 illnesses and one death. The manufacturer recalled its product — apple juice. For the pediatrician, Pickering said, E. coli O157:H7 in apple juice is a real problem because so many children drink apple juice daily. People should only drink apple juice that has been pasteurized. After it is opened, it should be refrigerated.
The major vehicle for transmission of E. coli O157:H7 is raw hamburger. However, transmission has also been reported from unpasteurized milk and apple cider, lunch meats, lettuce, mayonnaise, yogurt and potatoes. The organism has also been isolated from contaminated water; person to person transmission has also occurred. "There have been outbreaks in child care centers, hospitals and in families," Pickering said.
The incubation period is about three to four days with a range of 10 days. The first symptoms are abdominal pain, which is a hallmark of the disease. About one-third of individuals with E. coli O157:H7 will experience fever, but for most, fever is not a problem. Then non-bloody diarrhea will occur. A small percentage will develop hemorrhagic colitis and hemolytic uremic syndrome.
The best cure is prevention. Make sure hamburgers are cooked until the juices run clear and that uncooked food is stored and prepared separately from raw meat.
The first therapy for children would be administration of fluids and electrolytes, which is the "hallmark of therapy for all children who have diarrheal disease." Don't use antimotility agents because they can worsen the disease. There have been no controlled studies to determine whether patients with hemorrhagic colitis should receive antimicrobial agents, so this is a gray area.
The protozoa are popular media stars. A cryptosporidiosis outbreak in 1994 affected more than 400,000 people who lived in Milwaukee. Cyclospora made the headlines last summer when a national outbreak occurred among several hundred individuals who ate strawberries. The symptoms are cramping, severe diarrhea, nausea and mild fever.
Cryptosporidium and Cyclospora seem to defy the best water treatment facilities because the oocysts of these organisms are difficult to kill. This means that surveillance is important and guidelines for prevention, especially among immunocompromised people, are needed.
Cryptosporidium, which occurs worldwide, can be transmitted from water contaminated by animal feces. "Cyclospora is transmitted through water, and that is probably what happened to the strawberries. They were contaminated with water somewhere along the line," he explained.
Cyclospora generally are not transmitted person to person because the oocysts generally have to be out of the body for about 14 days before they develop to a stage in which they can transmit disease. "In other words, we are not going to see outbreaks in child care centers," he said.
Anything that is exposed to water could be a source of infection. Tell parents to wash all fruit and vegetables, and stress that these organisms are of particular concern to immune deficient individuals. They cause watery diarrhea and weight loss.
Experts are unsure whether antimicrobial agents work against Cryptosporidium although azithromycin (Zithromax, Pfizer) is being evaluated. Trimethoprim-sulfamethoxazole is the treatment of choice for Cyclospora.
Viruses also share the limelight. In 1995, there was a report of oyster-associated gastroenteritis. "Oysters sit at the bottom of the bay and filter hundreds of gallons of water until they are harvested. So, it is not surprising that people who eat oysters get sick by ingesting microorganisms that get caught in these little critters," Pickering said.
Caliciviruses, astrovirus, enteric adenovirus and rotavirus are prevalent in the United States, with rotavirus playing a leading role in children. "More children are hospitalized with rotavirus than the other enteric viruses," he said. Rotavirus causes diarrhea, usually accompanied by emesis and low-grade fever. Fluids and electrolytes are important to correct dehydration, and several companies are working on a vaccine.
Asymptomatic infections are common. "Half of the children we follow in child care centers with rotavirus infection are asymptomatic. Half of the infections due to astrovirus are asymptomatic," he said. These asymptomatic infections probably serve as immunizing events.
Norwalk virus is one of several caliciviruses which are transmitted person to person. Outbreaks occur in child care centers. The virus is found in contaminated shellfish, cold food and water. Caliciviruses cause a rotavirus-like illness. They are harder to diagnose than rotavirus because the virus is not shed as long. Luckily, illness is not as severe. Treatment is supportive.
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