Although there are more than 2,500 serotypes of this genus (class or group), for the sake of this column, we'll address only two – typhoid fever and nontyphoidal Salmonella. Were you around in the ’40s and ’50s, you will remember both of these - typhoid fever because of that darned shot mothers made us take after school was out each summer and nontyphoidal Salmonella because of the occasional outbreaks of gastroenteritis following picnics.
Typhoid fever is reported 400 to 500 times annually in the U.S., primarily from travelers returning from endemic (peculiar to a specific place) regions. Transmission is from human to human only, there is no animal intermediary. Typhoid bacteria are shed in the stool or urine of folks with active disease or in the stool of asymptomatic carriers (remember Typhoid Mary?). The organism enters the body via the GI tract and gains access to the bloodstream. In endemic areas where sanitary measures are generally inadequate, these bacteria are transmitted more frequently by water than by food. In more developed countries, transmission is chiefly by food that has been contaminated by healthy carriers. Flies may be a culprit in spread here also.
After an incubation period of eight to 14 days, symptoms begin gradually with fever, headache, joint pain, sore throat, poor appetite, and abdominal pain, followed by florid diarrhea. In up to 10 percent of untreated patients, the entire spectrum will recur in a week or so.
Diagnosis can be made or confirmed by the culture of blood, urine, and/or stool. Without antibiotics, the mortality rate is about 12 percent, but with prompt therapy that rate falls to one percent or less.
In endemic areas, travelers should avoid eating raw leafy vegetables or other foods served at room temperature and drinking untreated water. Milk should be pasteurized, and chronic carriers should not be allowed to handle foods. A live-attenuated vaccine is available and is about 70 percent effective. It should be given every other day for a total of four doses.
Nontyphoidal Salmonella Infection, called “Salmonellosis”, often referred to as “food poisoning”, is found world-wide with tens of millions of cases reported annually. Infections are more common in the summer, and children are more likely than adults to become infected. The most common way to acquire salmonella is by eating meat or eggs or drinking milk that's contaminated, or fruits or vegetables that have been fertilized by manure from infected animals. Pets can carry this nasty little bug, including those little turtles that were so popular decades ago.
gastroenteritis is the most common manifestation, and after an incubation period of 12-48 hours, one develops nausea, cramping abdominal pain, followed by diarrhea, fever, with occasional vomiting and bloody stools. The disease is usually mild, lasting one to four days without treatment. There can uncommonly be more severe manifestations including “enteric fever”, joint, soft tissue, urinary tract, and nervous system problems due to blood stream invasion.
The diagnosis can be made by culturing stool or other infected sites. Routine testing of the patient with gastroenteritis is not indicated, the possible exceptions being infants, the elderly, those with immune deficiencies, returning travelers, and those with bloody diarrhea.
Risk factors include immune deficiencies (to include malignancies and those on chemotherapy), those with no spleen, sickle cell anemia, and those whose stomach secretes no acid (either due to surgery or to medication). Even though one cannot tell by site or smell which foods are contaminated with salmonella, there are things you can do to lessen your chances of acquiring it:
l Avoid eating raw or barely cooked eggs;
l Don't eat raw or undercooked beef, pork, or poultry;
l Refrigerate food promptly, both before and after cooking it;
l Wash your hands well with soap and water before handling food;
l Don't mix cooked with raw foods or use the same utensils to prepare them;
l Cook each kind of meat to its correct minimum temperature;
l Wash raw fruits and vegetables well, and peel if possible.
If one has bloody stools, dehydration, or ongoing high fever, you should consult your physician.
Dr. William McKell is a Northsider.