Following up here on the associations between parasite infection and reduced incidence of autoimmune diseases such as diabetes, thyroid disorders, arthritis and possibly asthma, this time with a specific focus on Schistosome infection. Schistosomias is a common infection in many areas of the developing world, and is thought to be the second most important human parasite after malaria. Infection may be sub-clinical with little or no indication of infection.
Osada et al. (2009) reported on lower inflammation and less arthritic response in infected mice. Arthritis can be induced in mice by injecting them with Collagen II. A recent publication by Xiao-Ping Chen's group (He et al. 2010) further report that the inhibitory effect of schistosomiasis is dependent on the life stage of the schistosomes. Schistosomes have a very complex life cycle and apparently some phases are more protective or induce different physiological responses in the host than others. Acute infection and egg-laying by the parasite are associated with less response to the collegen injections. Very interesting.
However, it is not advised that people run out and attempt to infect themselves, which can be pretty horrible and disfiguring. Malnutrition, anemia and lowered IQ have been observed in infected children, and increased incidence of bladder cancer is seen among infected adults. Still, it will be interesting to see where this work goes, and what treatments may be eventually developed. Thank you Osada et al. and He et al.
He, Y., Li, J., Zhuang, W., Yin, L., Chen, C., Li, J., Chi, F., Bai, Y., & Chen, X. (2010). The inhibitory effect against collagen-induced arthritis by Schistosoma japonicum infection is infection stage-dependent BMC Immunology, 11 (1) DOI: 10.1186/1471-2172-11-28
Araújo, M., Hoppe, B., Medeiros Jr, M., & Carvalho, E. (2004). Schistosoma mansoni infection modulates the immune response against allergic and auto-immune diseases Memórias do Instituto Oswaldo Cruz, 99 DOI: 10.1590/S0074-02762004000900005
OSADA, Y., SHIMIZU, S., KUMAGAI, T., YAMADA, S., & KANAZAWA, T. (2009). Schistosoma mansoni infection reduces severity of collagen-induced arthritis via down-regulation of pro-inflammatory mediators International Journal for Parasitology, 39 (4), 457-464 DOI: 10.1016/j.ijpara.2008.08.007