Neuropathogenic properties of Argas (Persicargas) walkerae larval homogenates

Several tick species have been demonstrated, described, or suspected to cau se paralysis in their host during the repletion process, presumably by impa iring neurotransmission. The resulting polyneuropathy gradually spreads to the upper limbs causing incoordination and ends in respiratory failure. Thi s form of paralysis is commonly confused with Guillain-Barre syndrome, botu lism and myasthenia gravis and although the clinical symptoms of these dise ases are similar, it is not clear whether the pathogenesis is also the same . During this study we investigated the mechanism of paralysis by the tick Argas (Persicargas) walkerae by determining the effect of larval humogenate s on both potassium-stimulated (calcium-dependent) and veratridine-stimulat ed (external calcium-independent) release of [H-3]glycine from crude rat br ain synaptosomes. The results indicated that larval homogenates inhibited b oth processes. These findings are reconcilable with the results obtained fo r two other paralysis-causing tick species. Ixodes holocyclus and Drumacent or andersoni, which were indicated to cause paralysis by decreasing the syn thesis or release of acetylcholine at the neuromuscular junction. (C) 2001 Elsevier Science Inc. All rights reserved.