Foodborne illnesses are a global concern that significantly impact public health and food safety systems. While most people are familiar with common culprits like Salmonella, Escherichia coli (E. coli), and Listeria monocytogenes, there are other dangerous but less frequently discussed pathogens that continue to infect thousands of people annually. Among these are Hepatitis A virus, Norovirus, and Cyclospora cayetanensis, each capable of causing severe illness, especially in vulnerable populations.
According to Ron Simon, the nation’s leading food poisoning lawyer:
“Though often grouped under the broader umbrella of food poisoning, these pathogens are unique in their biology, transmission, and treatment. Each of these organisms infect people in their own way, but there are things consumers can do to protect themselves from these hidden threats.”
1. Hepatitis A Virus (HAV)
What is Hepatitis A?
Hepatitis A is a viral infection that affects the liver and is caused by the Hepatitis A virus (HAV). Unlike bacterial foodborne pathogens, HAV does not multiply in food but instead enters the body when contaminated food or water is consumed. The virus targets the liver, causing inflammation that can result in symptoms ranging from mild flu-like discomfort to severe liver damage in rare cases.
How It Spreads
HAV is primarily transmitted through the fecal-oral route, which means it spreads when someone consumes food or drink contaminated with infected feces. This can occur in several ways:
- Infected food handlers not washing their hands properly
- Consumption of raw or undercooked shellfish from contaminated waters
- Drinking water contaminated with sewage
- Eating raw fruits and vegetables irrigated or washed with contaminated water
Notably, HAV is extremely resilient, capable of surviving outside the body for weeks, even in harsh environments.
Symptoms
Symptoms usually develop between 15 to 50 days after exposure and can include:
- Fatigue
- Nausea and vomiting
- Abdominal pain (especially near the liver)
- Dark urine
- Pale stools
- Jaundice (yellowing of the skin and eyes)
Unlike chronic hepatitis B or C, Hepatitis A does not cause chronic liver disease, but the acute infection can be severe and, in rare cases, fatal.
Incidence and Outbreaks
Despite being vaccine-preventable, Hepatitis A continues to cause outbreaks globally. In the United States, outbreaks have often been traced to imported food products such as frozen strawberries, pomegranate arils, or green onions. One notable 2013 outbreak was linked to imported pomegranate seeds used in a frozen berry mix, infecting over 160 people across multiple states.
Prevention
- Vaccination is the most effective defense against HAV.
- Ensure proper hand hygiene, especially for food service workers.
- Wash fruits and vegetables thoroughly.
- Cook shellfish thoroughly and avoid raw seafood from questionable sources.
2. Norovirus
What is Norovirus?
Often referred to as the “stomach flu” (although unrelated to influenza), Norovirus is the leading cause of acute gastroenteritis worldwide. It’s responsible for over 19 million illnesses annually in the United States alone, according to the CDC. Although it’s a major public health issue, it often flies under the radar compared to more “famous” foodborne illnesses.
How It Spreads
Norovirus is exceptionally contagious. Just a tiny amount (fewer than 20 viral particles) can cause infection. It can be transmitted via:
- Contaminated food or water
- Touching contaminated surfaces and then touching your mouth
- Close contact with infected individuals
Outbreaks are common in confined environments like cruise ships, schools, nursing homes, and restaurants.
In terms of food, high-risk sources include:
- Leafy greens
- Fresh fruits
- Shellfish, particularly oysters
- Ready-to-eat items handled by infected food workers
Symptoms
Symptoms pf Norovirus typically appear 12 to 48 hours after exposure and include:
- Nausea
- Vomiting (more common in children)
- Diarrhea (more common in adults)
- Stomach cramps
- Fever and body aches
While symptoms generally resolve in 1–3 days, Norovirus can cause severe dehydration, especially in infants, elderly adults, and people with weakened immune systems.
Incidence and Outbreaks
Because it’s so contagious and resistant to many common disinfectants, Norovirus can rapidly spread through a population and contaminate large quantities of food.
Prevention
- Wash hands thoroughly and regularly.
- Do not prepare food if you are sick or have been recently sick.
- Rinse fruits and vegetables well.
- Cook shellfish to safe temperatures.
- Disinfect surfaces with solutions containing chlorine bleach, as alcohol-based sanitizers are often ineffective against Norovirus.
3. Cyclospora cayetanensis
What is Cyclospora?
Cyclospora cayetanensis is a protozoan parasite that causes a gastrointestinal illness called Cyclosporiasis. Unlike viruses and bacteria, Cyclospora is a single-celled organism that must mature in the environment before becoming infectious. That means it’s not typically spread directly from person to person.
Cyclospora is considered a less common foodborne pathogen in developed nations, but it has caused increasing numbers of outbreaks due to the global food supply chain and increased importation of fresh produce.
How It Spreads
Humans become infected with Cyclospora by ingesting food or water contaminated with the parasite’s mature oocysts. The most commonly implicated foods include:
- Fresh herbs (e.g., basil and cilantro)
- Leafy greens (e.g., romaine lettuce)
- Berries (especially raspberries and blackberries)
Unlike HAV or Norovirus, Cyclospora must sporulate in the environment (typically taking several days to weeks) before it becomes infectious, which makes direct person-to-person transmission unlikely.
Symptoms
Symptoms typically begin about a week after infection and include:
- Prolonged watery diarrhea (can last weeks or more)
- Loss of appetite
- Weight loss
- Bloating
- Fatigue
- Nausea
If untreated, symptoms can persist for weeks to months, often relapsing. While not typically life-threatening, it can seriously impact quality of life.
Incidence and Outbreaks
The United States sees hundreds to thousands of cases per year, many linked to imported produce. For example, a 2019 outbreak linked to fresh basil imported from Mexico sickened over 200 people in 11.
Because Cyclospora contamination often occurs before the food reaches the consumer, at the point of origin or during processing, it’s especially difficult to control without proper agricultural hygiene standards.
Prevention
- Wash produce thoroughly, although washing may not always remove Cyclospora.
- Support better agricultural practices and supply chain traceability.
- Stay informed about CDC food recall alerts.
- When traveling to developing countries, avoid raw produce unless peeled or properly cooked.
Comparison Table: Hepatitis A, Norovirus, and Cyclospora
| Feature | Hepatitis A | Norovirus | Cyclospora |
|---|---|---|---|
| Type of Pathogen | Virus | Virus | Parasite |
| Incubation Period | 15–50 days | 12–48 hours | ~7 days |
| Duration of Illness | Weeks to months | 1–3 days | Weeks to months |
| Key Symptoms | Jaundice, fatigue, nausea | Vomiting, diarrhea, cramps | Watery diarrhea, fatigue, weight loss |
| Transmission Route | Fecal-oral | Fecal-oral, surface contact | Contaminated food/water |
| Person-to-Person Spread | Yes | Yes | No |
| Common Food Sources | Shellfish, frozen berries, produce | Leafy greens, fruit, shellfish | Basil, lettuce, berries |
| Treatment | Supportive care; vaccine prevention | Supportive care; hydration | Antibiotics (e.g., TMP-SMX) |
| Vaccine Available | Yes | No | No |
| Seasonality | Year-round, more common in spring/summer | Peaks in winter | Summer outbreaks common |
Public Health Impact and Challenges
Despite being less frequently discussed than bacteria like Salmonella or Listeria, these three pathogens pose unique public health challenges. Norovirus remains the most common cause of foodborne illness outbreaks, but its coverage in food safety conversations is surprisingly limited compared to its actual impact.
Hepatitis A outbreaks have been increasing in recent years, particularly among at-risk populations such as the homeless or drug users, but food-related cases continue to emerge. Cyclospora’s connection to global supply chains makes it especially difficult to control without international cooperation and better farm-to-table monitoring.
One shared challenge in managing these pathogens is the difficulty of detecting contamination before symptoms emerge. Since all three can be present on fresh produce or in prepared foods without any visible signs, consumers must rely on preventative hygiene and policy interventions from producers, restaurants, and governments.
What Can Consumers Do?
While it’s nearly impossible to eliminate all foodborne illness risks, consumers can reduce their exposure to these lesser-known pathogens with some practical precautions:
- Practice Safe Food Handling: Always wash hands before preparing food. Clean fruits and vegetables under running water. Use separate cutting boards for raw meats and produce.
- Stay Informed: Follow public health announcements from the CDC and FDA.
- Advocate for Food Safety: Support local and national efforts to increase inspections, require vaccination for food workers, and improve sanitation practices.
- Be Cautious When Traveling: In regions with known sanitation issues, stick to bottled water, avoid raw foods, and be cautious with street food.
- Don’t Prepare Food When Sick: If you’ve had vomiting or diarrhea recently, especially within 48 hours, avoid preparing food for others.
Hepatitis A, Norovirus, and Cyclospora
While Hepatitis A, Norovirus, and Cyclospora may not dominate headlines the way E. coli or Salmonella do, their impact on public health is real and significant. Each of these pathogens infects thousands of people annually through contaminated food or water and can cause long-lasting or severe symptoms.
By increasing public awareness, improving hygiene practices, and strengthening food safety systems at both local and global levels, we can reduce the prevalence of these infections and protect the health of consumers worldwide. As our food systems grow increasingly global and complex, staying informed about these “under-the-radar” threats becomes not only wise—but essential.
