Schistosomiasis or bilharzia, is a common parasitic disease which can cause bladder dysfunction and hematuria, and even correlate with bladder cancer and increase HIV susceptibility with urogenital lesions. Globally, it is estimated that more than 240 million people infected. Within endemic areas, children carry the heaviest burden of infection. Its treatment intensively depends on PZQ, which has replaced other antischistosomal drugs and become a regular first-line therapy. However, given that PZQ has been widely used for almost 40 years, the emergence of schistosomal resistance under drug selection pressure has received much attention. With the increase in schistosomiasis, the serious threat of PZQ resistance requires adequate monitoring of current mass drug administration programs. Thus, novel alternative intervention are in high demand and in this study we use hyperthermia to prevent and treat schistosomiasis as a result of its heat sensitivity.
High temperature has been used to treat illnesses dating back to as early as 5000 years ago. Magnetic hyperthermia is currently a clinical therapy that is approved for treatment of tumor cells . Tumors can be shrunk by the effects of hyperthermia treatment, through the selective killing of cancer cells by damaging proteins and cellular structures. Recently, similar successful therapies have also been reported in treating acne vulgaris, mild-to-moderate inflammatory acne and cutaneous leishmaniasis.
A skin-hyperthermia device (Figure 1) designed by Tsinghua university was applied for targeting migrating skin schistosomula and to expand on the in vitro findings on pre-treatment on cercariae, which is a novel method for treating the skin phase of a parasite infection.
The data obtained from the revealed that with the thermal dosages increased, the survival rate of cercariae decreased from 70% to 0% which indicated the preventing effect of hyperthermia (P < 0.05). When treated with thermal dosages above 45°C, the the survival rate of cercariae ranged from a 50%. reduction to almost 100% compared with control groups. Moreover, when the S. japonicum infected mice was treated by heating the cercarial-contact region of skin, the worm reduction rates (WRR) reached 83.1% (P < 0.05).
The sensitivity of adult schistosomes to heat was also investigated by a microwave hyperthermia device (Figure 2A). The WRR, hepatic shift rates and egg reduction rates were 23.7%, 40% and 30% respectively after treated with thermal dosages of 42~43 °C for 20 min. Although it was failed to exceed the group of PZQ, encouraging results have been obtained that hyperthermia could be an effective preventing method.
"To the best of our knowledge," wrote the researchers, "This work by far the first report that applying hyperthermia therapy in Schistosoma japonicum cercariae and skin-phase schistosomula. It apply the novel low-cost, convenient and non-toxic method as soon as possible after the appearance of cercarial dermatitis, which can have early benefit in prevention strategies of the desease."
This research was funded by the Bill & Melinda Gates Foundation (Grant no: 1024516)
See the article:
YANG Huixia , TANG Tao, HE Pei, ZHANG Youren, XIE Le, LIU Guangqi, LI Li, KONG Weichao, LI Jingdingsha, LIU Ruiting, LI Yukun, HU Junjian, WANG Xiaowen, LI Liya, XIANG Guanghong , GOBERT Geoffrey , LI Yuesheng, TANG Jintian. A novel and effective hyperthermia method for Schistosomiasis japonica prevention and treatment, Science Bulletin, 2015, 60(16): 1461-1464.
Science China Press