Christmas ham is a staple food during the holidays. Households also offer ham as a gift to friends and loved ones. However, experts warn the public to be cautious when serving purchased ham or when preparing home-cooked types this Christmas season, as parasites can potentially thrive in ham, and could cause disease.

According to medical experts, pork, the main ingredient of ham, can be contaminated by the parasite Trichinella spiralis (T. spiralis).

Microbiologist Dr. Windell Rivera said "Pwedeng mag-cause ng trichinosis, ito ay isang foodborne illness ([The T. spiralis parasite] can cause the foodborne illness trichinosis)."

Humans can be infected by T. spiralis through eating raw or undercooked meat which may have cysts or encrusted parasite larvae. Larvae, according to US-based Centers for Disease Control and Prevention, are released after the cysts are exposed to stomach acids.

Experts said rodents are common hosts of the bacteria in the food cycle. Once carnivorous or omnivorous animals eat carcasses of infected animals, the parasites invade the linings of their small intestines. The acid in their digestive system breaks down the covering of the parasite and releases the worms. These worms eventually mature and spread to other parts of the body.

The same could happen within a human body once individuals ingest contaminated meat product experts said.

Once a person is infected, nausea, vomiting, and diarrhea may appear 1-2 days after infection. Further infection could lead to fever, muscle pain, and headaches. Worse cases may cause meningitis, pneumonia, or even death.

Trichinellosis however, is not contagious. Its only main source of contamination is through consumption of infected meat. Hence the public must be cautious when preparing and serving meat products such as ham.

Although most purchased ham have already gone prior cleaning and cooking, experts suggest cooking the meat before serving to kill off any parasite or bacteria that may have conta