When it comes to food poisoning, what you don't know can hurt you.

It’s commonly believed that food poisoning always causes acute bouts of diarrhea and vomiting. But in the past few years, I hospitalized two patients with this all-too-common affliction who had neither of those symptoms.

One of the men had a six-month history of intermittent fever, weight loss, night sweats, and joint pain. The second was hospitalized with high fever, confusion, and stiff neck.

The causes of their problems were initially unclear. But on further examination and testing, both turned out to have food poisoning—illness caused by contaminated food or water.

Each year, according to estimates by the Centers for Disease Control and Prevention, about one in six Americans is sickened by a foodborne illness. Of those, 128,000 require hospitalization and 3,000 die.

Food Poisoning Misconceptions Are Common

Symptoms do usually consist of varying combinations of nausea, vomiting, diarrhea, abdominal pain, and fever. But many people may be unaware that food poisoning doesn’t always lead to gastrointestinal grief, as evidenced by the two very sick people described above.

Some other facts about food poisoning also seem to have evaded many of us. For example, the majority of people who responded to a 2016 Food and Drug Administration survey believe that restaurant meals are more likely than home meals to be the cause of food-borne ills.

It’s true that your health is in the hands of kitchen personnel when you’re dining at the local bistro. But food that’s poorly prepared or incorrectly stored at home can also make you sick.

Also, although 66 percent of the FDA survey respon­dents felt that it was “very likely” that chicken may harbor germs, only 6 percent said the same of vegetables. The truth is that both chicken and produce can be germ-laden.

On the plus side, some 90 percent of the survey takers reported that they either clean cutting boards after using them or change to a different cutting board after prepping raw meat, poultry, or fish.

But fewer than half said they scrub up after cracking raw eggs—notorious for containing salmonella organisms. The majority also said they wash chicken prior to cooking, a habit that won't eliminate bacteria but can contaminate other foods and surfaces.

The Culprits Are Varied

A variety of organisms can cause food poisoning. The most common include norovirus (a highly contagious virus, known for infec­ting multiple people on cruise ships), salmonella (found in meat, poultry, eggs, and produce), E. coli (one cause of traveler’s diarrhea), hepatitis A virus (often in raw shellfish), campylobacter (common in poultry), and listeria (typically found in delicatessen meats and soft cheeses). Some organisms, such as botulinum and staphylococcus, produce a potent toxin that does the damage.

If you suspect food poisoning, adequate fluid ingestion is key to avoiding complications. I usually advise fruit juices and canned chicken broth to replace the lost fluid and electrolytes (mostly sodium and potassium).

Antibiotics are not usually needed. Antidiarrhea medications such as loperamide (Imodium A-D and generic) and diphenoxylate with atropine (Lomotil and generic) do little to help—and could hinder recovery.

Most cases of food poisoning end on their own within a week or so. See your doctor if symptoms last more than three days (24 hours for infants and seniors), abdominal pain is severe, or you have an oral temperature higher than 101.5° F. For signs of dehydration (weakness, increased thirst, decreased urine output, lightheadedness), hospitalization might be needed for rehydration with intra­venous fluids.

In rare instances food poisoning can be fatal, as in the case of botulism—which can occur as a result of improperly prepared at-home preserves. Symptoms such as confusion, dizziness, numbness and tingling, and double or blurry vision constitute an emergency and warrant imme­di­ate medical attention.

When Symptoms Are Out of the Norm

And for my patients with the unusual symptoms? The first turned out to have brucellosis, which is an uncommon foodborne disorder.

How did we figure this out? While taking his medical history, I learned that he was a devotee of unpasteurized milk, which is a source of the brucella organism. He responded to a combination of antibiotics given over an eight-week period.

The second patient, a butcher, was ultimately diagnosed with listeria meningitis. This, we learned, was a result of his failure to wash his hands or wear gloves when handling raw meat in his shop. In his case, treatment with antibiotics was a lifesaver. 

Editor's Note: This article also appeared in the April 2017 issue of Consumer Reports on Health.