Helminths and protozoa make up the two major classes of parasites that infect humans. While we know these are prevalent infections in developing countries, one common misconception in industrialized nations is that parasitic infection is a thing of the past, which is most certainly not the case.
What are Helminths and Protozoa?
Protozoal parasites are microscopic single-celled organisms while helminths are multi-cellular worms that can often be seen with the naked eye. Parasites most commonly infect the gastrointestinal system, but can infect other tissues in the human body. While parasites are most commonly acquired through international travel, there are other ways to acquire them, including from living or working closely with animals.
Are they always bad?
Some protozoal and helminthic organisms are a healthy and vital part of our microbiome and are involved in balancing our immune system. There are several branches of our immune system, including the Th1, Th2, Th17, and Treg subtypes of T cells involved in cell-mediated immunity. All of these subtypes of activity are necessary to mounting a healthy immune response against pathogenic invaders. Imbalances in one or more of these areas can contribute to autoimmune disease, chronic infection, allergies and mast cell activation syndrome, and cancer, to name a few.
Out of Balance
Some parasitic organisms can be problematic, however. Undiagnosed and untreated parasitic infections can contribute to immune dysregulation that can aggravate allergy syndromes, worsen chronic infections (think Lyme and co-infections), lead to nutritional deficiencies, and contribute to hormone and neuro-psychiatric imbalances. These organisms can also be opportunistic, meaning they shift from being relatively harmless when you are healthy, to wreaking havoc when you are under high physical and emotional stress.
In fact, because currently available parasitic testing tends to be poor at detecting their presence, these organisms can be secretly responsible for the lack of improvement seen when attempting to treat these conditions.
Who should consider parasites?
We de-worm our pets, so why do we not de-worm ourselves? Empiric treatment (that is, treatment given on the basis of clinical evaluation rather than on definitive lab criteria) for parasitic infection can be helpful when comprehensively addressing complex immune disorders, including Lyme and co-infections, mold and other environmental toxicity, autoimmunity, and allergic syndromes such as mast cell activation.
If you have a history of international travel, chronic infections, allergies, or environmental illness, and are not improving despite treatment, consider parasites. While our initial reaction to this may be one of shock and disgust, these organisms really are common (and are sometimes healthy, even). Accounting for them may make quite the difference.