As the Cyclospora parasite continues to tear through the U.S., food safety has become a major source of stress for many Americans. The recent Cyclospora outbreaks, however, represent only the tip of the iceberg when it comes to foodborne diseases. All around the world, invasive parasites have wreaked havoc by infesting food, causing millions of deaths over the years.

A new report from the World Health Organization (WHO) has highlighted just how rampant foodborne parasites are, estimating that around 171 million illnesses worldwide were attributable to foodborne transmission of invasive parasites in 2021 alone. Although the impact of these diseases has slightly declined in many parts of the world, many are on the rise and don’t get nearly the same kind of attention that cyclosporiasis has been getting.

“Foodborne parasitic diseases are still causing serious problems for people around the world,” said study author Christine Budke, a professor at Texas A&M University who contributed to the WHO global estimates, in a statement. “We can’t afford to forget about them.”

Estimating Foodborne Parasitic Diseases

For the new study, researchers used a measurement known as disability-adjusted life years (DALYs), which combines years of life lost due to premature death and years of healthy life lost due to disability or illness.

Using DALYs, they measured the global burden for 14 parasitic diseases from 2000 to 2021. Building upon previous estimates from 2010, the new study notably included Trypanosoma cruzi, a single-celled parasite that causes Chagas disease, which is common in Central and South America.

Based on their analysis, the researchers estimated that 277 million illnesses were caused by potentially foodborne invasive parasites in 2021, and among these illnesses, approximately 171 million were attributed to foodborne transmission.

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Nematodes at the Top

According to the Centers for Disease Control and Prevention, three main classes of parasites can cause disease in humans: protozoa, helminths, and ectoparasites. Protozoa are single-celled organisms, helminths are parasitic worms, and ectoparasites include ticks, fleas, lice, and other parasites that feed on the outer surface of a host.

In the new study, the researchers found that infections from nematodes (a type of helminth) accounted for the most foodborne illnesses, representing 143 million cases. Most of these nematode cases came from ascariasis, which is an infection of the roundworm Ascaris lumbricoides. The illness, contracted after ingesting contaminated soil, food, or water, is most prevalent in the tropical and subtropical areas of Asia, sub-Saharan Africa, and the Americas.

After nematode infections, systemic protozoal infections caused about 26.2 million cases of foodborne parasitic illness. These were mostly tied to toxoplasmosis, an infection from the protozoan parasite Toxoplasma gondii that’s often acquired from eating undercooked meat.

Overlooked Illnesses

The parasitic disease associated with the highest estimated mean number of foodborne deaths in 2021, according to the researchers, was neurocysticercosis, which led to over 13,000 deaths. This disease is caused by the larval stage of the pork tapeworm, which can infect the brain and cause epilepsy.

After neurocysticercosis, the next disease associated with the most deaths was clonorchiasis (over 10,000 deaths). Clonorchiasis is one of the major reasons why the Western Pacific is seeing a significant increase in the burden of foodborne parasitic illnesses, compared to other regions where incidence of these illnesses is decreasing. The researchers suggest the surge of clonorchiasis may have to do with increased consumption of undercooked fish in urban areas of China.

The researchers conclude that diseases like Chagas disease and clonorchiasis, despite being mostly restricted to certain regions, are imposing a severe burden on low- and middle-income communities with a lack of resources to combat them. While Cyclospora may seem like a big deal in the U.S., other parts of the world are suffering from their own parasitic threats.

“We tend to gravitate toward the new headline diseases,” Budke said. “Meanwhile, these neglected diseases continue impacting communities, affecting people’s ability to work, support their families, and thrive.”

This article is not offering medical advice and should be used for informational purposes only.

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Article Sources

Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:

• This article references information published in The Lancet: WHO estimates of the global, regional, and national foodborne burdens of 14 invasive parasitic diseases, 2000–21: an updated data synthesis
• This article references information from the CDC: About Parasites