By: James Peacock
Shigella poisoning is one of the most common causes of gastrointestinal illness in the United States. As we have seen in a recent outbreak caused by Souplantation in California, Shigella bacteria have the capability to spread rapidly through a restaurant or crowded area. One of these crowded areas that frequently is the source of Shigella poisoning outbreaks are daycares. In the past few weeks, a couple of outbreaks have begun to be investigated by health officials in Kentucky and Florida. The outbreak in Florida was linked to a daycare, while the outbreak in Kentucky is almost exclusively limited to children of daycare age.
An outbreak of Shigellosis is currently being investigated by the Lincoln Trail District Health Department. There are currently about 50 cases of illness linked to this outbreak. Those sickened in the outbreak are from two counties in Kentucky: Nelson and Hardin. The vast majority of cases are in young children. Young children are at an increased risk of developing a serious case of Shigella poisoning for several reasons, including a weakened immune system and a lack of proper personal hygiene. Shigella infections predominantly occur in children. The CDC reports that the incidence rates of Shigella in children under five years of age are five times higher than in adults. Preliminary testing of samples done by investigators shows that the type of bacteria responsible for this outbreak is Shigella sonnei, the most common form of Shigella in the United States. Health officials continue to investigate this outbreak. A source has yet to be determined, but day care centers across the area are working diligently with health officials in an effort to prevent the further spread of infection.
Health officials in Seminole County are also working to investigate a Shigella outbreak that is spreading through a local daycare. Health officials first reported the outbreak on June 27, and have managed to find a source. Kids City USA in Altamonte Springs, Florida, has been linked to the Shigella outbreak. Health officials have not reported on exactly how many cases of illness have been caused by this outbreak, but they have reported that secondary exposure has caused some parents to become ill as well. Investigators have not been able to ascertain when or how the outbreak spread, but are working with the daycare to prevent further cases of illness. The daycare has been allowed to stay open, but a note was sent to parents by the daycare and health officials saying that any child exhibiting symptoms of Shigella poisoning — namely diarrhea — be kept home until they are symptom-free for two days.
Shigella bacteria are known to infect a large number of people in a very short amount of time. It can be transmitted from person to person with relative ease, making it a leading cause of outbreaks in crowded places such as daycares, cruise ships, and restaurants. This ease of transmission has placed Shigella bacteria among the most common forms of foodborne illness, causing a CDC-estimated 500,000 cases of illness per year. Shigella bacteria represent a genus of several different bacterial species. Most of these Shigella bacteria can cause illness in humans, including Shigella sonnei, Shigella boydii, Shigella flexneri, and Shigella dysenteriae. Shigella dysenteriae and Shigella boydii are not as common in the United States but remain a large issue in developing countries. Shigella sonnei is typically the mildest of the Shigella bacteria, causing only watery diarrhea. S. flexneri and S. boydii can cause mild to severe infections depending on the person. S. dysenteriae often causes the most severe infections and can produce Shiga toxins. Shigella bacteria are quite fragile and cannot survive high temperatures or acidic environments. Shigellosis, the illness caused by Shigella bacteria, is typically only spread from person to person via the fecal-oral route. Improper hygiene is one of the leading reasons for the spread of Shigellosis. The especially applies to handwashing, as improper handwashing is one of the leading ways that Shigella infections are spread. Shigellosis is also spread when food is prepared by someone who has a Shigellosis infection. Practicing proper hygiene, proper cooking techniques, and other preventative measures can help limit the risk for a Shigellosis infection. Outbreaks caused by Shigella bacteria have been connected to lettuce, potato salad, milk, tuna salad, dairy products, shrimp salad, poultry, chicken salad, and macaroni salad. With diseases like Shigellosis, an ill person can still be contagious even after the illness has subsided. Shigella bacteria can remain in the stool for up to two weeks after the symptoms of infection go away. This is why it is important to maintain these health and safety practices even after an illness goes away.
Only a few Shigella cells, between 10 and 200, are required to cause an infection. Shigellosis will begin to show symptoms between eight and fifty hours after exposure to the bacteria. Most cases of illness will present with symptoms including diarrhea that is often bloody, cramps, abdominal pain, fever, and vomiting. Much of the time, Shigellosis is self-limiting and can resolve itself in around 5 to 7 days. Some cases of Shigellosis may be more severe and cause complications. Those with certain risk factors, including the elderly, children, and those with suppressed immune systems are at an increased risk of developing a severe case of Shigellosis. Complications associated with Shigellosis include mucosal ulceration, dangerous levels of dehydration, reactive arthritis, rectal bleeding, and hemolytic uremic syndrome (HUS). HUS is caused by Shiga toxins and can damage red blood cells. These blood cells are then sent to the kidneys in order to be filtered out. The attempted removal of these damaged blood cells can damage the kidneys. The damage from the filtration process, coupled with the increased rate of damage inflicted on the kidneys by Shiga toxins, can lead to serious kidney damage and even kidney failure. If a case of Shigellosis has progressed to HUS, symptoms such as decreased frequency in urination, fatigue, and loss of color in the eyes and cheeks will be present. HUS is a very serious complication that needs to be treated as quickly as possible. For more information about this dangerous complication, click here. While Shigella poisoning may go away on its own, antibiotics are often prescribed to limit and end the infection. If you or a loved one begins to show the symptoms of Shigellosis, monitor their condition closely and take them to a health professional if necessary.