Print version ISSN 0104-7930
On-line version ISSN 1678-4936
J. Venom. Anim. Toxins vol.7 no.2 Botucatu Dec. 2001
EPIDEMIOLOGICAL SURVEY OF SCORPION ENVENOMATION IN SOUTHWESTERN MOROCCO
1 Laboratory of Terrestrial Animal Ecology - Department of Biology, P.O. Box 2390 - Faculty of Sciences Semlalia - Marrakech 40 001 - Morocco
ABSTRACT: The high frequency and severity of scorpion envenomation in Morocco is a serious public health problem, especially in semi arid and arid areas with a large rural population.
In view of this alarming situation, we have conducted this investigation on scorpion envenomation in the Haouz and Souss plains between 1994 and 1998. Preliminary results have shown a high rate of scorpion envenomation with several deaths. With the exception of Scorpio maurus, the suspected species are generally anthropophilous, which belong to the Androctonus genera of the Buthidae family. The Buthidae family is responsible for 96.93% of the envenomings. In the southwestern Morocco, the death rate is of about 3.84%. The Androctonus mauretanicus is responsible for 60% of deaths. We show the various therapeutic modalities used by the local populations and propose prophylactic measures, such as awareness and prevention.
KEY WORDS: scorpions, scorpion envenomation, epidemiology, prevention, Southwestern Morocco, Haouz, Souss.
Scorpion envenomation is a major public health problem in southwestern Morocco and in the rest of the country with many deaths. However, up to now no epidemiological survey has been conducted to evaluate the importance of scorpion envenoming in Morocco. We decided to do an investigation on scorpion envenoming on the same lines as an ecological and biogeographical survey in this region of Morocco (19,20,21) From the species we studied, some are known by the high toxicity of their venoms, and their stings are often deadly. The results of this inquiry can be used as references during later regional inquiries.
The southwestern Morocco has the advantage of combining various ecological features (cultivated plains, mountainous areas, and coastal dunes), demographic features (urban concentrations, and higher and lower density farming areas) with climatic features of Atlantic dominance in the West and continental in the East. The objective of our investigation is to specify some epidemiological characteristics of scorpion envenomation in order to understand some of the methodological consequences that will serve as a basis to our evaluations of impact and morbidity.
The most dangerous species are found in North Africa, the Middle East, and Latin America (13,14), and they belong to the Buthidae family (7), except in Madagascar and Australia where the autochthonous Buthidae do not cause any particular medical problems (8). The dangerous species belong to the Centruroides and Tityus genera in Latin America, and to the Buthacus, Androctonus, and Leiurus genera in North Africa and in the Middle East (7,14). In Morocco, with one exception, the scorpion species belong to the Buthidae family. In southwestern Morocco, six species are responsible for envenomations, and with the exception of the Scorpio maurus (Linné, 1785), they belong to the Buthidae family.
1 Androctonus mauretanicus (Pocock, 1902) is a black scorpion very commonly found in houses, where it prefers dark places. As well as living in houses, it lives in rocky or stony places, gardens, cemeteries, and old constructions. It can also be found in burrows left by lizards and rodents. It is one of the most dangerous species in Morocco and is responsible for the highest number of serious, often deadly envenomings, especially in children (6,22). This species is responsible for several deaths upstream the studied region. In the studied region, two subspecies have been distinguished (19):
1a A. mauretanicus mauretanicus (Pocock, 1902) living in the Haouz plain, the Ouarzazate plateau, the Sirwa mountains, and the High Atlas below 2000 meters of altitude, where it is scarce; 1b A. mauretanicus bourdoni (Pocock, 1902) living in the southern flanks of the High Atlas and the Souss plain.
2 Androctonus aeneas (Koch, 1839) liouvillei (Pallary, 1924) is a black scorpion found under rocks that can be seen in and around human dwellings. It lives in the South of the Ant-Atlas and the Draa valley (19). This very agile scorpion is responsible for several cases of child deaths (6,15).
3 Buthotus franzwerneri (Birula, 1914) gentili (Pallary, 1924) is known for its color and hairy tail. This scorpion lives in rocky areas. It does not seem to dig burrows but it can be found in human dwellings. It is frequently found in the South of the studied region (19), being responsible for several cases of envenomation, especially in the South of the High Atlas, where it is abundant. For a long time its danger has been ignored (12), but it has been responsible for some deadly envenomations in the studied region.
4 Buthus occitanus (Amoreux, 1789) is the most common scorpion in southwestern Morocco. It lives in different areas, but it is not anthropophilous. It can take refuge under stones, rocks, and litter where it can dig burrows or hide bark. In France, this species is not at all dangerous (12). In Morocco, its sting is less dangerous than the other species. In Algeria and Tunisia, however, it is responsible for several deaths (3). In the Algerian Atlas, Sergent (16) reported three cases of sting by this scorpion that were followed by very serious complications, of which two ended in death: one child of 8 and a man of 35.
Four subspecies all endemic to Morocco has been distinguished in the studied region (20):
4a B. occitanus malhommei (Vachon, 1949) lives in the Haouz plain; 4b B. occitanus paris (Koch, 1839) in the northern and western Central High Atlas below 1300 meters of altitude; 4c B. occitanus mardochei (Simon, 1878) in the Souss plain, the Haha region, southern borders, and the western limit of the High Atlas as far as the Atlantic coastline; and 4d B. occitanus tunetanus var. lepineyi Vachon (1949) at high altitudes. We encountered it in the High Atlas between 1100 and 2600 meters of altitude.
5 Buthus atlantis atlantis (Pocock, 1889) is a brown yellow, burrowing, and endemic scorpion to the stationary dunes in the Atlantic coastline (19). Nothing is known about its venom toxicity, but inhabitants of Tiznit and Essaouira regions have said that this species is responsible for serious but not deadly envenomations.
6 Scorpio maurus (Linné, 1758) is a species characterized by robust clamps that are used for digging very deep burrows with oval openings. This scorpion of light brown to brown dark in color and is extensively found in the area of survey, where it is represented by three subspecies (19): 6a S. maurus weidholzi (Werner, 1929) living in the Haouz plain; 6b S. maurus fuliginosus (Pallary, 1928) in the High Atlas flanks between 900 and 2000 meters of altitude; and 6c S. maurus mogadorensis (Birula, 1910) in the Atlantic coastline, the Haha region, the west extremity of the Western High Atlas, and the Souss plain.
All envenomations by S. maurus are in children who try to dislodge them from their borrows and are stung on the hands. This scorpion sting is not dangerous and the pain caused is only felt at the sting site. According to the local people, the pain is similar to that of a wasp or a bee. Stings by the Chactoides (group containing the Scorpionidae and the Diplocentridae) are sometimes accompanied by local lesions (1,8).
PATIENTS AND METHODS
As reports of the number of scorpion envenomations are still unofficial, and the number of cases is underestimated every year, it would beneficial to link the hospital records with a survey of the local inhabitants. Our survey included a prospective investigation. All people stung by a scorpion were interviewed. A questionnaire including information about the envenoming, the species, and the measures taken after the sting was completed for every envenomed patient.
Our investigations were concentrated on the areas the Haouz and Souss, the inhabitants of the High Atlas, the Ouarzazate plateau, the southern flanks of the Anti-Atlas and the Draa valley (Figure 1).
Between 1994 and 1998, 912 victims have been studied. The results emphasize a balance between the number of envenomations and the evaluations of the people at risk. The scorpiofauna of the region has been surveyed by a series of prospecting investigations in farming and urban areas, human dwellings, and isolated areas with no inhabitants. The surveyed specimens are deposited in the Laboratory of Terrestrial Animal Ecology of the Faculty of Sciences Semlalia of Marrakech.
RESULTS AND DISCUSSION
Scorpion Species Involved in Envenomings
In the studied region, some scorpion stings cause only slight reactions, whereas others may cause death.
The Buthidae family is responsible for 96.93% of the envenomings in this area, with Scorpionidae causing 3.07% (Table 1). The only species of the Scorpionidae family in Morocco, S. maurus, is a strictly burrowing species that spends most of its time hidden in deep galleries that it digs under stones or in the bare earth. It has almost no contact with man.
A. mauretanicus, essentially ananthropophilous species is responsible for 47.59% of envenomings, with B. occitanus causing 26% (Table 1). B. franzwerneri gentili and A. aenea liouvillei account for 14.25% and 9.1%. A. mauretanicus is the most dangerous of these, being responsible for 60% of deaths (Table 2), with B. franzwerneri gentili and A. aeneas liouvillei responsible for 25.71% and 14.29%, respectively.
Areas of the human body more prone to scorpion stings
Analysis of our data showed that feet and hands are the most affected parts of the body (62.17% of cases) (Table 3). Walking barefoot at night or putting on shoes without having shaken them is dangerous, especially on hot summer nights. The hands are at risk when carelessly investigating scorpion shelters, such as holes, borrows, under stones, etc. Involvement of the head, stomach, neck, back, thighs, legs, and arms account for 37.83% of the cases.
Envenomed patients distribution according to age and sex
The highest number of envenomings (37.83%) occurred in the 16 to 30 age group (Table 4), the 15 and below age group accounted for 22.15%, the 31 to 45 age group 20.18%, and the 46 and over 19.85%.
It appears that the severity of symptoms following envenomation is inversely related to the age of the victim. From the people studied, there were 35 deaths from envenomations (3.84% of the cases). They were all in the 2 to 17 age group; 82.86% were less than 15, and 42% were less than 5 years old (Table 5).
These results corroborate the observations of Ben Salah et al. (1) and Goyffon et al. (10) in Tunisia, Sofer and Gueron (18) and Gueron et al. (11) in Israel, El Amine et al. (5) in Saudi Arabia, and Berg and Tarantino (2) in the United States of America. Goyffon and Heurtault (8) showed that the risk of mortality is much higher in young patients.
From the studied patients, men (57.24% of cases) are more exposed to scorpion envenomations than women. This tendency is probably due to the high number of men working in farming areas.
Seasonal and daily variations in scorpion envenomation
Envenomations by all species present very significant seasonal and daily variations. We registered 58.88% of envenomings occurring in the summer, 19.08% in the spring 17.11% in the autumn, and 4.93% in the winter (Figure 2). Scorpions are especially thermophilous and are more active during the hot season and less active during the colder seasons.
Daily variations (Figure 3) show 41.01% of envenomings occur between 1800 and 0600 hours, 40.57% between 1200 and 1800 hours with 40.57%. Scorpions are more active during higher temperatures and can attack when disturbed. The number of envenomations by B. occitanus during this period is essentially due to farming activities in the fields on hot summer days. The same observations have been reported by Goyffon et al. (10) in Tunisia. The period between 0600 and 1200 presents 18.42%, the lowest number of envenomings. The animals return to their burrows after a long night of hunting.
Popular treatments and folklore related to scorpions
The struggle against scorpion envenomation in the southwestern Morocco remains associated with traditional medicine (even near health centers). There are numerous empirical practices that vary according to the region. Some of these procedures are judicious, ligature upstream of the sting, scarification of the sting site, direct suction of venom by mouth.
The most common of the traditional treatments is the incision of the sting site followed by pulverization of the envenomed site with cold cooking gas. Other materials placed at the sting site, such as raw meat, chopped garlic, natural honey, killed and crushed offending scorpion, amber or cotton moistened by ammonia water. Other methods are oral administration of tea containing amber, salt, sugar or honey.
To protect people against venomous animals certain tribes glue a piece of paper with a few words on the top of all doors of the house, which according to them scares away dangerous animals including scorpions. Frames of windows and doors are sometimes sprayed with comfrey, using its odor to repel arachnids.
In the studied populations, 38,27% of scorpion envenomations are treated exclusively using traditional cures (Table 6), 27.52% modern methods (serotherapy), 26.97% using both, and 7.24% of cases are taken straight to hospital without prior treatment.
The use to traditional cures in most farming communities is due to their beliefs in the efficiency of traditional medicine. However, the remoteness and small number of health centers serving these regions impede access to serotherapy. However, both types are often used. In this case, traditional methods are used as first aid until the patient reaches the nearest health center or if modern methods do not improve the patient's condition. In 7.24% of cases, no treatment is given because either the offending species is not dangerous S. maurus (Table 1) or the sting is not deep enough and sufficient venom has not been inoculated. However, it is important to mention that in several regions we heard of certain people "immunized" against scorpion venoms, which we did not manage to confirm.
Of the cases ending in death, 10 used only traditional treatments (Table 7), 16 used both, and nine used only serotherapy.
Serotherapy only would be useless if the time elapsed between the sting and the arrival at the health center was more than two hours because of the fast spread of venom and the patient required hospital observation (22). In urban areas, patients are systematically sent to hospital, whereas in farming areas only the serious cases are transferred. According to Sergent (17), more than four hours after the sting, injection of antivenom is less likely to be successful, but should still be given.
In southern Morocco, essentially in the farming areas, several false beliefs well explain the ignorance associated with these arachnids, for example:
"The black scorpions are always considered the most dangerous", as according to current tradition, everything that is black is more dangerous than others. Venom toxicity is not linked to scorpion color (4). Indeed several non-black scorpions are deadly, such as A. australis (yellow to brown yellow in color), Leiurus quinquestriatus, and B. occitanus (yellow in color).
"The male scorpion is always more dangerous than the female." No difference has been found in venom composition between both sexes of the species (9).
"The tail of the male black scorpion has seven rings." This scorpion, according to local folklore, is always deadly. However, the number of caudal segments is constant within the order of scorpions and this number is always equal to six including the telson.
In most regions, people that are envenomed by scorpions are anxious to crush it due to the false belief that the envenoming cannot be healed unless the offending scorpion is killed.
Prophylactic measures to minimize scorpion envenomations in southwestern Morocco
In view of the severity of scorpion stings in this region of Morocco, some prophylactic measures must be taken in order to try to reduce envenomations and to decrease morbidity and secondary sting mortality.
To decrease the impact of scorpions is necessary:
A. At the scorpion level:
1. collect scorpions from in and around human dwellings. These can be used to manufacture antivenom;
2. introduce domestic predatory animals, such as chickens, ducks, turkeys, cats, and hedgehogs;
3. decontaminate in and around human dwellings using insecticides that cause no harm to humans and other animals.
B. At the population level:
1. educate local people about conditions that foster envenomations, such as lack of hygiene and disregard for their surroundings;
2. remove stones and garbage, real resting places of scorpions. Hedges (Jujube, Fig-tree of Barbarism) can be good shelters for scorpions;
3. avoid climbing plants close to houses because scorpions are good climbers;
4. use tar and electricity to move scorpions away;
5 protect feet at night by wearing appropriate footwear;
6. check, invert, and shake footwear vigorously before putting them on especially in the morning;
7. avoid sleeping on the ground at night especially in the summer.
To decrease morbidity and secondary mortality:
1. inform people in distant farming areas of the clinics, the importance of antivenom, and the understanding of the severity of the condition in that the patient needs health care;
2. inform of procedures to be taken immediately after the sting: apply tourniquet upstream of the sting to prevent the spread of venom, scarification and suction, decontamination using bleaching-water, place ice on the sting site until the whole area can be immersed in wet crushed ice, and educate people into recognizing scorpions and taking them to health centers;
3. standardize health center treatment, using specific antivenom;
4. maintain all envenomed patients under constant observation for several hours and be ready to apply more antivenom if serious symptoms appear;
5. hospitalize all patients as soon as possible.
In southwestern Morocco, scorpion envenomation causes serious problems to local populations, with some mortality. We noted that envenomation severity depends on:
1. the offending species, especially as some species are very dangerous, sometimes deadly;
2. the victim's age;
3. the time of the day or season;
4. the delay in hospitalization, as fast intervention is a prime factor for success. It is advisable to identify the scorpion species and to hospitalize all victims especially children.
Sanitation education and good environmental hygiene practices can considerably reduce the number of envenomings.
The importance of the scorpion envenoming in southwestern Morocco encourages us to try and remedy this problem and provide special care to outlying farming area populations. After prevention, serotherapy is still the most efficient tool against scorpion envenomations. For this reason, it appears necessary to perform biochemical and pharmacological characterization of venoms from certain dangerous scorpions in the studied area and to help to contribute to the development of specific antivenom.
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Received 02 February 2000
Accepted 15 May 2000
O. TOULOUN - Laboratory of Terrestrial Animal Ecology, Department of Biology, P.O. Box 2390, Faculty of Sciences Semlalia, Marrakech 40 001, Morocco.