African Journal of Neurological Sciences Pan African Association of Neurological Sciences ISSN: 1015-8618 Vol. 17, Num. 1, 1998

FARID W., DEBROCK C., MACHARIA W., PREUX P.M.

Department of Neuropsychiatry, Alexandria General Hospital Ras Erin, Alexandria, Egypt. Institute of Tropical Neurology School of Medicine, Limoges, France.

SUMMARY

To determine the effect of the timing of scorpion sting, and that of whole blood exchange on the mortality, we studied 82 cases presenting at a rural health center in Egypt. Fourty six patients received only classic traetment, and 36 patients received the classic treatment and whole blood exchange. The mortality rate was significantly higher for early night stings and for the group treated classically. Undue visits scorpion infested areas is to be avoided in the early night period. Whole blood exchange seems beneficial as addition therapy to the classical methods. Further studies need to be done to clarify this benefit.

82 cas de morsures de scorpion survenues dans une zone rurale du centre de l'Egypte ont ete etudies afin de determiner l'influence sur la mortalite: du moment de la morsure dans la journee et aussi de l'efficacite du traitement par transfusion de sang.

46 patients ont eu un traitement classique et 36 une transfusion. La mortalite a ete significativement plus elevee lorsque la morsure avait lieu au debut de la nuit ainsi que sur le groupe traite classiquement.

La frequentation des lieux ou il y a beaucoup de scorpions est deconseillee au debut de la nuit.

La transfusion de sang associee a la therapeutique classique parait efficace. Il faudrait entreprendre d'autres etudes pour preciser cette efficacite.

KEYWORDS: scorpion sting - Egypt

Egypt is one of the countries of the arid regions extending from North Africa to India, inhabited by one of the most dangerous scorpions (9)Androctonus australasis and related species that are highly mortal (10). Areas in Egypt and Egyptian deserts are inhabited by both venomous scorpions and venomous snakes, e.g., Egyptian cobra, horned snakes and vipers. Hecht (7) demonstrated that the mortality rate from scorpions is usually higher than from snakes. Children are more affected particularly during summer, many cases are fatal (5). In general scorpion envenomations present with neuronal and musculoskeletal signs and symptoms, among other systemic manifestations. Almost all body systems are affected, but circulatory shock and pulmonary oedema are the usual cause of death (5). Some scorpion venoms, particularly Androctonus australis, are hemotoxic and may cause severe hemolysis {2, 11}. Currently treatment is based on scorpion antivenom, calcium gluconate, diazepam, atropine sulphate and hydrocortisone (3,6,8).

This study was done in order to clarify the effect of body weight and the timing of the sting on scorpion envenomation and the benefit of whole blood exchange on the nervous system morbidity. Two hypothesis tested were low body weight and early night scorpion stings may have a negative effect on the neuromorbidity and mortality, because high body weight could be associated with low serum venom concentration, and that scorpion venom load is higher during the early night period; and that the exchange of whole blood to reduce the venom load has a positive effect. These results could be useful in community-based management of scorpions and acute management of envenomation.

All patients presenting with scorpion stings in Sebaeya, a rural health center in Aswan Governate, Egypt, were evaluated for a period of 12 months in 1990. During that period 82 cases presented to the health centre of which 54 were males and 28 females (sex ratio=1.9). On average it took the patient between 30 minutes to 2 hours to reach the health center after the stings. After a thorough physical examination and a detailed neurological examination (1), the clinical manifestations were analysed and classified appropriately. The time and the position of stings were recorded as well as the body weight of patients. Stings occurring between 5-7 am were classified as early morning, those occurring between 6-9 pm were classified as early night and those stung between 9pm -5am as intervening night. Usually scorpions feed at night and remain hidden during the day in crevices or burrows or under wood, loose bark, or rocks on the ground.

Patients were programmed to receive either the standard therapy or standard therapy plus fresh whole blood exchange. Group 1 received the standard therapy comprising of application of pressure dressing and cold packs to the sting site to decrease the absorption of venom. Then symptomatic treatment was given appropriately to control symptoms like hypertension, hypotension, pulmonary oedema and cardiac dysrythmias. All patients also received nonspecific scorpion anti-venin. Group 2 received above treatment as in group 1, and in addition 3000 ml of fresh whole blood was exchanged.

For statistical analysis Chi-2 Pearson test or Fisher exact test were used.

The neurological clinical manifestations are tabulated in Table 1. Forty six patients received standard treatment (Group 1).

Table 1- Neourological manifestations in scorpion stings Egypt, 1990 (n=82).

Thirty six patients received standard therapy and fresh whole blood exchange (Group 2). Table 2 and 3 show the respective prognosis of the two groups against patients weight and the time of the sting.

 Table - 2 Prognosis of group 1 (patients treated by standard treatment alone), Egypt, 1990 (n=46).

Physical examination revealed that 68% of stings were in the foot region and distal parts of the leg. In group 1, no significance difference was found in the number of stings in early morning, early night and intervening period of night. Case mortality rate of early night stings was significantly higher than that of early morning (p<0.01 ) and that of the intervening time of night (p<0.05) in this group. The morality rate in early night was still higher than combined mortality for early morning and intervening period of night (p<0.01 ). However the difference in mortality between early morning stings and that of the intervening time of night was not significant.

Group 2 had a significantly higher tendency to be stung in the early night and intervening period of night (p<0.001 ), while no significant difference was found between the number of stings in early night and early morning. No significant difference existed between mortality rate in early night and that of early morning. Furthermore, no significant difference was found either, between early night and intervening time of night, or between early night and any other time.

Body weight did not affect (significantly) the mortality rate in the two groups, at all ages.

The case mortality rate for early night for group 1 was significantly higher than for Group 2 (p<0.02). However when the total period of exposure (early night, early morning and intervening time) was considered, the difference in mortality did not reach the level of significativity (p= 0.06). For the intervening time of night case mortality rate was not significantly higher for Group 1 than for Group 2, and finally for early morning stings no significant difference occurred between case mortality rate of patients treated traditionally and those treated by additional fresh whole blood exchange.

In areas inhabited by both venomous scorpions and venomous snakes, the mortality rate from scorpions is usually higher because they live around houses and bites are more common.

Table 3 - Prognosis of group 2 (patients treated by standard treatment and fresh whole blood exchange), Egypt, 1990 (n=36).

Dudin and collegues (14) had found that the severity of symptoms and signs was not related to sex, age or weight but most likely dependent upon the susceptibility of the individual and/or the dose of venom injected by the scorpion. Our study seems to support this notion as the body weight had any significant effect on the mortality rate.

Early night stings appear more lethal probably because of a higher venom volume injected per sting with subsequent sting by the same scorpion delivering less and less venom. There was a significant reduction in mortality in Group 2 in the early night stings (the most dangerous) for patients who received fresh whole blood exchange. These results should be handled with prudence as this study was not a randomized or placebo-controlled trial. Additionally it is admitted that fresh whole blood exchange requires serological screening for infectious agents which may be difficult to obtain in certain circumstances in developing world. What is certain is that blood exchange when executed correctly is a relatively low risk procedure.

These results suggest that undue visits to the infested areas at the early period are very dangerous and should be avoided. If not possible, it is recommended that one should be armed with boots, flash light, and should look for treatment as rapidly as possible. Standardized antivenin prepared from local scorpions are available at Egypt Serum and Vaccine Institute, Centers of Toxicology, Cairo, and in the rural health centers. Infested areas can be sprayed with Gammaxane emulsion by a rate of 500 mg per square metre. However fresh whole blood exchange could be given in all scorpion sting patients presenting with systemic neurological and autonomic dysfunction. Using this procedure reduction of venom load, and that of excitatory neurotransmitters and acute reactants occurs with a consequent prevention of grave outcome. We feel that whole blood exchange is a safe time honoured procedure that could be used, when the prognosis is vital.

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