Effects of parasitic worms on the immune system

Effects of Parasitic Worms on the Immune System

Lymphocyte activation

Parasitic worms, also known as helminths, have a profound impact on the immune system of their hosts. These effects can be both beneficial and detrimental, influencing the host's susceptibility to other diseases and the overall immune response. Helminths include a variety of species such as nematodes, cestodes, and trematodes.

Immune Modulation

Helminths have evolved complex mechanisms to modulate the host's immune system to ensure their survival. They can induce a regulatory environment that suppresses inflammatory responses, which can be beneficial in reducing autoimmune diseases and allergies. This modulation is primarily achieved through the induction of regulatory T cells and the production of anti-inflammatory cytokines such as IL-10 and TGF-beta.

Th2 Immune Response

Schistosoma species

Helminth infections typically induce a Th2 immune response, characterized by the production of cytokines like IL-4, IL-5, and IL-13. This response is associated with the activation of eosinophils, mast cells, and IgE production, which are crucial for combating parasitic infections. However, a strong Th2 response can also lead to immunopathology and exacerbate conditions such as asthma.

Immune Evasion

Parasitic worms have developed strategies to evade the host's immune system. These include antigenic variation, secretion of immunomodulatory molecules, and the ability to mimic host molecules. Such strategies help the parasites to persist in the host for extended periods, often leading to chronic infections.

Impact on Autoimmune Diseases

There is evidence suggesting that helminth infections can protect against autoimmune diseases such as multiple sclerosis, type 1 diabetes, and inflammatory bowel disease. The "hygiene hypothesis" posits that the lack of exposure to helminths and other pathogens in developed countries may contribute to the increased prevalence of autoimmune and allergic diseases.

Impact on Allergies

Trichuris trichiura, male

Helminth infections can also influence the development and severity of allergic diseases. While some studies suggest that helminths can reduce the incidence of allergies by modulating the immune system, others indicate that they can exacerbate allergic responses, particularly in individuals with a genetic predisposition to allergies.

Helminth Therapy

The potential therapeutic use of helminths or their products to treat autoimmune and allergic diseases is an area of active research. Helminth therapy involves the deliberate infection of patients with controlled doses of helminths to modulate the immune system and alleviate symptoms of immune-mediated diseases.

Related Pages

• Helminthiasis
• Immune system
• Autoimmune disease
• Allergy
• Hygiene hypothesis

Elephantiasis caused by lymphatic filariasis

See Also

• Parasitology
• Immunology
• Neglected tropical diseases