* Immature immune systems: Their immune systems are still developing and haven't encountered as many pathogens as adults, making them less able to fight off bacteria, viruses, and parasites that cause foodborne illness.
* Limited gastric acidity: Their stomach acid is less acidic than adults', which is a crucial first line of defense against many foodborne pathogens. A less acidic environment allows more pathogens to survive ingestion.
* Poor hygiene practices: Young children often have less developed handwashing habits and may put things in their mouths more frequently, increasing their exposure to contaminated surfaces and food.
* Dietary habits: Their diets might include foods that are more likely to be contaminated (e.g., unpasteurized milk, honey), and they may consume larger quantities of food relative to their body weight, increasing their exposure to pathogens.
* Behavioral factors: They are less likely to understand and follow food safety guidelines.
* Underlying health conditions: Some infants and preschoolers may have pre-existing health conditions that weaken their immune systems and make them more susceptible to foodborne illnesses.
In short, the combination of a developing immune system, less effective bodily defenses, and increased exposure to pathogens and contaminated food makes them particularly vulnerable.