Human evolution and parasitic infections have run hand-in-hand since antiquity. Humans can be hosts to nearly 300 species of parasitic worms. Some cause death, suffering and economic loss in both developing and developed nations and research is ongoing to develop vaccines for these infections.
Can some worms offer health benefits?
People become infected by consuming worm eggs or by their skin being exposed to infectious larvae in faecally contaminated food, water or soil. The eggs hatch and the worms live in our bodies where they can cause sickness, and impair mental and physical development.
Found in the northern parts of Australia and in many tropical countries, and more prevalent in children, roundworms include whipworms, threadworms and hookworms. Some of them cause life-threatening diseases.
Whipworms, common in countries with warm, humid climates, are transmitted by swallowing soil contaminated with eggs, but some outbreaks have been traced to contaminated vegetables.
Threadworms can be spread by direct contact with other infected individuals or in food, dust, or other articles.
Hookworms suck blood from their human host, causing, in severe infestations, anaemia, fever, diarrhoea or constipation. They can slow down children’s growth and may even stop people from thinking and moving properly.
The most prevalent human tapeworm in Australia is the dwarf tapeworm. While most infected people do not have symptoms, this worm can cause diarrhoea, stomach pain, weight loss and weakness.
Called the ‘tapeworm diet’, tapeworm pills were sold as weight-loss aids in the early 1900’s!
Parasitic worms can affect our health, either by depriving our bodies of nourishment or because larvae find their way into other parts of our bodies, such as the blood, liver and brain, which stops our bodies working properly.
So why, in some instances, are patients being deliberately infested with them?
Research into helminthic therapy, also called worm therapy, began in the early 1990’s when a gastroenterologist expressed the idea that improved hygiene could be causing the surge in cases of asthma and allergies – on the rise in developed countries since the 1980’s. Involving deliberately infecting patients with parasitic worms to treat immune-mediated disease, it follows a possible explanation for the low incidence of autoimmune diseases and allergies in developing countries, contrasted with the significant and sustained increase in these diseases in developed, worm-free countries.
Worms have an ability to manipulate the immune system, which they need to do to survive. It is our immune system that cause inflammatory and autoimmune diseases such as asthma, inflammatory bowel diseases (IBDs) and food allergies.
One in every 70 Australians suffer from coeliac disease, where the immune system reacts abnormally to gluten, resulting in damage to the small bowel. While unconventional, worm therapy has shown promising results with certain autoimmune diseases and immune disorders, including coeliac disease.
In a trial funded by the National Health and Medical Research Council (NHMRC), the researchers attributed positive results to a protein, found in hookworms, which can keep the human immune response in check. Some patients’ symptoms of gluten intolerance reduced after being infected with hookworms.
Worms currently being studied include threadworms, hookworms, whipworms and a species of tapeworm – for diabetes, Crohn’s disease, ulcerative colitis, multiple sclerosis, rheumatoid arthritis, polyarthritis, asthma, eczema, dermatitis, hay fever, and food allergies. However, this form of treatment remains experimental and large scale (phase III) clinical trials have yet to be done to assess safety and efficacy. So far, efficacy is not looking promising in allergic disease.
If worm therapy eventually proves to be safe and effective for your complaint, and you are squeamish about hosting the little wrigglers, you might want to wait until they develop a ‘worm extract’ pill for a less ‘natural’ treatment.