Melarsomine hydrochloride (Cymelarsan®) fails to cure horses with Trypanosoma equiperdum OVI parasites in their cerebrospinal fluid

Vet Parasitol. 2018 Dec 15:264:47-51. doi: 10.1016/j.vetpar.2018.11.005. Epub 2018 Nov 9.

Abstract

The aim of this study was to evaluate the ability of melarsomine hydrochloride (Cymelarsan®) to cure horses suffering from a nervous form of dourine, a sexually-transmitted disease caused by Trypanosoma equiperdum. The recently described experimental model for assessing drug efficacy against horse trypanosomosis allowed us to obtain eight horses (Welsh pony mares) infected by T. equiperdum with parasites in their cerebrospinal fluid. The Cymelarsan® treatment evaluated consisted of the daily administration of 0.5 mg/kg of Cymelarsan® over 7 days. Two control horses remained untreated, three horses received the treatment 36 days p.i. and three horses received the treatment 16 days p.i. Following treatment, we observed parasite clearance in blood, stabilization of rectal temperature and a relative improvement in the mean packed cell volume levels for all treated horses. However, live parasites were later observed again in the CSF of all treated horses. Our results indicate the inability of Cymelarsan® to reach Trypanozoon located in the central nervous system of infected horses and thus discourage the use of Cymelarsan® to treat animals suffering from a nervous form of dourine.

Keywords: Cervical CSF sampling; Dourine; Equidae; Melarsomine hydrochloride (Cymelarsan(®)); Trypanosoma equiperdum.

MeSH terms

  • Animals
  • Arsenicals / standards
  • Arsenicals / therapeutic use*
  • Cerebrospinal Fluid / parasitology*
  • Dourine / cerebrospinal fluid*
  • Dourine / drug therapy*
  • Female
  • Horse Diseases / cerebrospinal fluid*
  • Horse Diseases / drug therapy*
  • Horse Diseases / parasitology
  • Horses / cerebrospinal fluid
  • Horses / parasitology
  • Treatment Failure
  • Trypanosoma / physiology

Substances

  • Arsenicals
  • melaminylthioarsenate