Pediatric Schistosomiasis Medication
- Author: Vinod K Dhawan, MD, FACP, FRCPC, FIDSA; Chief Editor: Russell W Steele, MD more...
Praziquantel (a pyrazinoquinolone) has become the main antischistosomal agent because it is effective against all human pathogens and is well tolerated orally. Other oral compounds available are oxamniquine (a nitroquinolone that is no longer available in the United States) and metrifonate (an organophosphorus cholinesterase inhibitor that is also unavailable in the United States), but these have limited parasite specificity.
Parasite biochemical pathways are different from those of the human host; thus, toxicity is directed to the parasite, egg, or larvae. The mechanism of action varies within the drug class. Antiparasitic actions may include the following:
- Inhibition of microtubules, causing irreversible block of glucose uptake
- Tubulin polymerization inhibition
- Depolarizing neuromuscular blockade
- Cholinesterase inhibition
- Increased cell membrane permeability, resulting in intracellular calcium loss
- Vacuolization of the schistosome tegument
- Increased cell membrane permeability to chloride ions via chloride-channel alteration
Animal studies report that praziquantel induces rapid contraction of schistosomes by exerting a specific effect on the permeability of the cell membrane. The drug further causes vacuolization and disintegration of the schistosomal tegument. It has a more marked effect on adult worms than on young worms. After oral administration, praziquantel is rapidly absorbed (80%). It is subject to a first-pass effect and extensive metabolism.
Oxamniquine is no longer available in the United States. It is active only against S mansoni. Oxamniquine is effective in disintegrating the schistosome tegument to which phagocytes attach, causing death.
The drug is well absorbed and is metabolized extensively to inactive metabolites that, in turn, are excreted in urine. The plasma half-life is approximately 1-2.5 hours, and a peak in drug concentrations is usually reached in 1-1.5 hours after oral administration.
Metrifonate, an organophosphate derivative with anthelmintic and anticholinesterase activity, is not available in the United States. It is used as an alternative to praziquantel for treatment of S haematobium infections; it is not effective for S japonicum or S mansoni infections. The drug is well absorbed from the gastrointestinal (GI) tract, with peak levels occurring 1 hour after administration.
Lapa M, Dias B, Jardim C, Fernandes CJ, Dourado PM, Figueiredo M, et al. Cardiopulmonary manifestations of hepatosplenic schistosomiasis. Circulation. 2009 Mar 24. 119(11):1518-23. [Medline].
Salvana EM, King CH. Schistosomiasis in travelers and immigrants. Curr Infect Dis Rep. 2008 Mar. 10(1):42-9. [Medline].
Chitsulo L, Engels D, Montresor A, et al. The global status of schistosomiasis and its control. Acta Trop. 2000 Oct 23. 77(1):41-51. [Medline].
Yosry A. Schistosomiasis and neoplasia. Contrib Microbiol. 2006. 13:81-100. [Medline].
Kallestrup P, Zinyama R, Gomo E, Butterworth AE, van Dam GJ, Gerstoft J. Schistosomiasis and HIV in rural Zimbabwe: efficacy of treatment of schistosomiasis in individuals with HIV coinfection. Clin Infect Dis. 2006 Jun 15. 42(12):1781-9. [Medline].
Xu X, Zhang Y, Lin D, Zhang J, Xu J, Liu YM, et al. Serodiagnosis of Schistosoma japonicum infection: genome-wide identification of a protein marker, and assessment of its diagnostic validity in a field study in China. Lancet Infect Dis. 2014 Jun. 14(6):489-97. [Medline].
Tsang VC, Wilkins PP. Immunodiagnosis of schistosomiasis. Screen with FAST-ELISA and confirm with immunoblot. Clin Lab Med. 1991 Dec. 11(4):1029-39. [Medline].
Kamal S, Madwar M, Bianchi L. Clinical, virological and histopathological features: long-term follow-up in patients with chronic hepatitis C co-infected with S. mansoni. Liver. 2000 Jul. 20(4):281-9. [Medline].
Richter J. Evolution of schistosomiasis-induced pathology after therapy and interruption of exposure to schistosomes: a review of ultrasonographic studies. Acta Trop. 2000 Oct 23. 77(1):111-31. [Medline].
Cao J, Liu WJ, Xu XY, Zou XP. Endoscopic findings and clinicopathologic characteristics of colonic schistosomiasis: a report of 46 cases. World J Gastroenterol. 2010 Feb 14. 16(6):723-7. [Medline]. [Full Text].
Hayashi S, Ohtake H, Koike M. Laparoscopic diagnosis and clinical course of chronic schistosomiasis japonica. Acta Trop. 2000 Oct 23. 77(1):133-40. [Medline].
McManus DP, Loukas A. Current status of vaccines for schistosomiasis. Clin Microbiol Rev. 2008 Jan. 21(1):225-42. [Medline].
Andersson KL, Chung RT. Hepatic schistosomiasis. Curr Treat Options Gastroenterol. 2007 Dec. 10(6):504-12. [Medline].
Doenhoff MJ, Hagan P, Cioli D, Southgate V, Pica-Mattoccia L, Botros S, et al. Praziquantel: its use in control of schistosomiasis in sub-Saharan Africa and current research needs. Parasitology. 2009 Nov. 136(13):1825-35. [Medline].
van der Vliet HJ, van Kemenade FJ, Hekker TA, Craanen ME. Schistosomiasis. Clin Gastroenterol Hepatol. 2005 Jun. 3(6):A26. [Medline].
Adam I, Elwasila E, Homeida M. Praziquantel for the treatment of schistosomiasis mansoni during pregnancy. Ann Trop Med Parasitol. 2005 Jan. 99(1):37-40. [Medline].