Tityus asthenes scorpion stings: epidemiological, clinical and toxicological aspects

Introduction. Scorpion stings are a public health problem in many countries. However, in Colombia, very few epidemiological, clinical or toxicological studies have been undertaken. Objective. Ecological and epidemiological aspects were related to the prevalence of scorpion stings by Tityus asthenes. The clinical features of envenomization were described in patients and in an experimental animal model. Materials and methods. The study was conducted in four localities of Mutata and Uraba Counties in the province of Antioquia, Colombia. The sample consisted of 1,593 (929 urban, 664 rural) of the 5,305 exposed people, inhabitating 324 households (188 urban (58%); 136 rural (42%) of 1,448 houses total in the study area. An interview survey was performed in every selected family for a more realistic estimate of sting prevalence. Additionally, a prospective study was directed toward patients presenting scorpion stings at care at the local hospital over an 18-month period. Results. The probability was 12.9 times greater of finding T. asthenes inside or around houses in places near to forest and high agrarian plantations (odds ratio=13). Eighty scorpion stings were reported in the retrospective study (4.1% prevalence [95% CI 3.3-4.8%]), but only 14 of the patients (17.5%) sought care in the local hospital (an 82.5% underreportage). Seventy percent of the stings occurred in rural places; 50% occurred in the locality of Caucheras, with an attack rate of 10.6%. The overall household infestation rate was 269% (95% CI 22.9-30.8%) and an area dispersion ratio of 100%. Signs of systemic envenomization occurred mainly in children (67%). The 50% lethal dose of T. asthenes venom was 121.6 mu g for 18-20 g Swiss Webster rats (95% CI 103.7-139.6). Immunodetection of T. asthenes and Centruroides gracilis/C.margantatus venoms in the experimental animals was possible when were tested by Western blot against Alacramyn(R) (Institut Bloclon, Mexico) and Soro antiaracnidico(R) (Instituto Butantan, Brasil) antivenoms. Scorpion interspecific differences were noted. Conclusions. The prevalence of stings by T. asthenes were common and their presence was associated with tropical rainforests. Envenomization at low density can be neutralized efficiently by anti-scorpion antivenoms produced in Mexico and Brazil but with differing specificities for the venom of each scorpion species.