|Year : 2022 | Volume
| Issue : 1 | Page : 45-53
Scorpion envenomations in Algeria
Schehrazad Selmane1, Mohamed Lhadj2
1 L'IFORCE, Faculty of Mathematics, University of Sciences and Technology Houari Boumediene, Algiers, Algeria
2 Beni Messous University Hospital Centre, Ministry of Health, Population and Hospital Reform, Algiers, Algeria
|Date of Submission||21-Jan-2022|
|Date of Acceptance||23-Feb-2022|
|Date of Web Publication||23-Mar-2022|
L'IFORCE, Faculty of Mathematics, University of Sciences and Technology Houari Boumediene, Algiers
Source of Support: None, Conflict of Interest: None
CONTEXT: Due to its climatic and ecological characteristics, Algeria shelters a diverse scorpion fauna and scorpion envenomations represent an actual public health issue.
AIMS: The purpose of this retrospective study was to bring word on the trend, spatial distribution, and spatial clustering of scorpion envenomations in Algeria.
MATERIALS AND METHODS: The Moran's I statistic was used to analyse the global spatial autocorrelation and the first order Queen's contiguity rule was used to specify the spatial neighborhood relationship.
RESULTS: A total of 1,274,154 scorpion sting accidents including 2347 deaths have been recorded from 1991 to 2020. In 2019, the incidence was 116.7 cases per 100,000 inhabitants, and only 3 of Algeria's 48 provinces were free of scorpion sting accidents. 47% of sting cases occurred in the Sahara, 46% in the high plateaus and 7% in the Tell and all southern provinces had an incidence varying between 162 and 827 cases per 100,000 inhabitants. The incidence rates exhibited spatial autocorrelation globally; all Moran index values ranged between 0.49 and 0.66 and all z-scores were greater than the critical value at 0.05 level of significance. The most significant hot spots were located in the Sahara and the high plateaus and the most significant cold spots were located in the tell.
CONCLUSIONS: There is a need to reframe the set objectives and the actions to be carried out taking into account spatial clustering, seasonality, and species spatial distribution. A good management can be achieved by active public participation at all levels of planning, decision-making, implementation, monitoring and evaluation.
Keywords: Algeria, scorpion sting, spatial autocorrelation analysis, spatial clustering, spatial distribution
|How to cite this article:|
Selmane S, Lhadj M. Scorpion envenomations in Algeria. J Prev Diagn Treat Strategies Med 2022;1:45-53
| Introduction|| |
The scorpion, a venomous predatory arthropod whose order belongs to Arachnida class, is one of the oldest animals on earth. In the world, 2649 valid species, 190 genera and 16–19 families are currently cataloged. The Buthidae family (the largest of the scorpion families with 95 genera and 1270 species) and the Hemiscorpiidae family (one genera and 16 species) include species dangerous to humans capable of killing humans in some cases within hours, even minutes.,
Scorpion envenomations represent a public health issue in some arid, semi-arid, or Saharan regions situated in the latitude band 50°N and 50°S of the equator. Around 2 billion people are estimated to live in areas at risk for scorpion envenomations. It is estimated that 1.2 million people yearly are victims of scorpion envenomations in the world. In terms of venomous animal-related human fatalities, they rank second after snakebites and are responsible for an estimated 3000 deaths each year. These estimates are limited to the few countries that have a reliable system for scorpion sting surveillance.,
Due to its climatic and ecological characteristics, Algeria shelters a diverse scorpion fauna. Scorpion envenomations represent an actual public health issue; the epidemiological situation revealed that 45 out of 48 provinces were affected by scorpion envenomation accidents in 2019; that is, 86% of the estimated population was at risk of scorpion stings.,
This study aimed to give an overview on scorpionism, to present the scorpion sting management protocol and to describe the spatiotemporal distribution of scorpion envenomations in Algeria.
| Materials and Methods|| |
The study area
Algeria is located in the Maghreb region of North Africa. Its landscape consists mostly of high plateaus (made up of 17 provinces whose area represents 13.3% of the country's area, and with an estimated population density of 53 people/km2 as of 2019) and the Sahara Desert (made up of nine provinces whose area represents 83.1% of the country's area and with an estimated population density of two people/km2 as of 2019), in addition to a hilly and narrow coastal plain along the Mediterranean Sea (made up of 22 provinces whose area represents 3.6% of the country's area and with an estimated population density of 265 people/km2 as 2019).
Scorpion envenomation and climate data
Data sources were the Ministry of Health for scorpion notifications on a yearly basis by province and National Statistics Office for population data.
Annual mean, maximum, and minimum temperature, annual mean relative humidity (RH), the annual precipitation amount and annual mean wind speed (km/h) were gained from the website (http://en. tutiempo.net/climate/ws-605500.html) which compiles and stores data from meteorological stations around the world.
Spatial autocorrelation analysis
The Moran's I statistic was used to analyze the global spatial autocorrelation. It supplies a unique measure of spatial autocorrelation for an attribute in a region as a whole. This statistic is a cross-product statistic between a variable and its spatial lag.
To specify the spatial neighborhood relationship, the first order Queen's contiguity rule was used. Values of Moran's I range from-1 to 1; the value 1 indicates highly positive autocorrelation and the value − 1 indicates highly negative autocorrelation, while 0 indicates spatially random distribution.
The higher the value is, the stronger the autocorrelation is. Its statistical significance is determined by the z-score and its associated P value. This statistic allows checking whether objects with similar attribute values are close to each other. The Moran Index does not supply guidance on spatial patterns. To identify local clusters and local spatial outliers, we made recourse to the local Moran's I statistic developed by Anselin in 1995. To identify the location and types of clusters, the local indicators of spatial association derived by Anselin were used.
A positive value for I indicates that adjacent locations have similar high or low values which form clusters. A negative value for I indicates that adjacent locations have dissimilar values. Outliers in which a high value is surrounded primarily by low values (high-low), and outliers in which a low value is surrounded by high values (low-high).,
Spatial autocorrelation analysis and mapping were carried out using GeoDa software (https://geodacenter.github.io/).
Scorpion envenomation prevention and management program
The Ministry of Health has instituted a prevention and management program in 1986. Since its implementation by National Committee against Scorpion Envenomation (NCSE), the program has been updated several times.,,
The protocol for scorpion envenomation
Under two headings, prevention and management, we summarize the instituted scorpion envenomation management protocol in effect since the last update in May 2020.,
From a preventive point of view
- Strengthening and intensification of information and communication with the different sectors (local authorities, education, religious affairs, media, and civil society) involved in the fight against scorpion envenomation for carrying out environmental hygiene actions
- Intensification of scorpion collection according to a well-studied timetable to reduce the density of scorpions and thus help reduce exposure to the risk of stings.
In terms of the management of stung subjects
A case of scorpion envenomation has been defined by the NCSE as any case of scorpion sting who visits a health facility. The therapeutic management depends on the clinical stage; the severity of scorpion envenomation calls for early treatment, both specific and symptomatic. It must be emphasized that the patient's grade can be changed and the passage to severe envenoming is generally unforeseeable, rapid, and often brutal.
Grade I: Mild sting
It is an asymptomatic clinical picture, as it may be characterized by the presence of one or more local symptoms: variable intensity pains at the point of sting, tingling, paresthesias, or burns that may be accompanied by numbness sometimes triggered by percussion or touch.
Therapeutic management consists of:
- A specific treatment aimed at neutralizing the venom by one antivenom vial intramuscularly and when necessary an adjuvant therapy
- Symptomatic treatment: To treat pain and stress
- Clinical monitoring: Pulse, blood pressure, temperature, and state of consciousness.
In that case, the patient is kept under observation between 4 and 6 h; the absence of worrisome symptomatology justifying its release.
Grade II: Moderate envenoming
The patient presents the general clinical signs, hyper or hypothermia, excessive perspiration, abdominal pain sometimes diarrhea.
- Hospitalization for at least 24 h
- Specific treatment: Antivenom vial
- Symptomatic treatment: Of pain, fever, vomiting, and bradycardia with atropine.
Grade III: Severe envenoming
Is characterized by the failure of at least one of the vital functions of the patient:
- Cardiovascular: Shock, arterial hypotension, tachycardia
- Respiratory: Acute pulmonary edema, polypnea, sweating, cyanosis, crackling sound on the lungs
- Neurological: Disturbance of consciousness, coma.
- Hospitalization in intensive care unit
- Serotherapy: One antivenom vial to be renewed every 3 h, until the 12th h
- Oxygen therapy
- Treatment of pain and fever
- Treatment of hypertensive emergency with Nicardipine
- Treatment of cardio-circulatory dysfunction with Dobutamine.
| Results|| |
The evolution of cases, incidence per 100,000 inhabitants, deaths and lethality of scorpion stings over the last three decades is illustrated in [Figure 1], where the lethality is the ratio between the number of deaths attributed to scorpion envenomation and the number of scorpion stings during the same period and it is expressed in percentage. The descriptive statistics of the yearly data are displayed in [Table 1]. A total of 1,274,154 scorpion sting accidents including 2347 deaths have been recorded from 1991 to 2020. The highest number of stings and deaths were recorded in 2007 and in 1999 respectively. The peak in the incidence and lethality were reported in 1999 and in 1991, respectively. The coefficient of variation (CV), defined as the ratio of the standard deviation to the mean, indicates that there is more variability in deaths (CV = 41%) and lethality (61%) in comparison to sting cases (CV = 21%) and incidence of stings per 100,000 people (17%).
|Figure 1: Yearly evolution of reported scorpion stings, incidence, deaths, and lethality in Algeria|
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To find any linear relationship between stings, deaths, and population size, the Pearson product-moment correlation coefficient ® between variables was estimated. Death cases and lethality were strongly correlated with population size. The correlation between death cases and scorpion sting cases was weak. The correlation between scorpion sting cases and population size was moderate [Figure 2].
|Figure 2: Scatter plot of yearly scorpion sting cases, incidence per 100,000 inhabitants, deaths, lethality, and population size from 1991 to 2020|
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In 2019, 3 of Algeria's 48 provinces were scorpion sting accidents free, compared to 10 in 2010 and 21 in 2000 [Figure 3]. In terms of population at risk, the estimated population at risk of scorpion sting accidents was 53% in 2000, 71% in 2010 and 86% in 2019.
|Figure 3: Geographical distribution of the scorpion sting incidence per 100,000 people in Algeria at the provincial level for the years 2000, 2010, and 2019|
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Descriptive statistics of the provincial scorpion sting incidence from 2000 to 2019 are provided in [Table 2]. Over two decades, Adrar province topped the list fifteen times, in terms of incidence while in terms of sting cases, the highest number was reported either in Biskra province or in El Oued province. In 2019, 47% of sting cases occurred in the Sahara Desert and 46% in the high plateaus and 7% in the tell. All southern provinces of the country had an incidence higher than the estimated national rate (116.7 cases per 100,000 inhabitants); it varied between 162 and 827 cases per 100,000 inhabitants. All Northern provinces had an incidence varying between 0 and 44 with Médea province as exception (157 cases per 100,000 inhabitants). There were 16 provinces that have recorded deaths and Biskra province topped the list by 7 deaths.
|Table 2: Descriptive statistics of the provincial scorpion sting incidence|
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All Moran index values were positive and ranged between 0.49 and 0.66 and all z-scores were greater than the critical value 1.96 at a level of significance of 0.05 as displayed in [Table 3]. Consequently, the incidence rates exhibit spatial autocorrelation globally.
|Table 3: Spatial autocorrelation analysis of scorpion incidence results: 2000-2019|
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The local spatial autocorrelation analysis outcomes [Figure 4] tell us that the most significant hot spots were located in the Sahara and the high plateaus, numbering no more than 11 and no <9. Six out of the eleven provinces of the country, namely Adrar-El Bayadh-Ghardaïa-Illizi-Ouargla-Tamanghasset, were permanently in the hot spots and this during the two last decades. On the other hand, the provinces numbering no more than 11 and no <6, exhibiting significant cold spots (low-low), were located in the Tell. Five out of the eleven provinces of the country, namely Guelma-Mila-Oran-Skikda-Tipaza, were permanently in the cold spots and this during the two last decades. Finally, the number of provinces in nonsignificant spots ranged between 26 and 30.
|Figure 4: Spatial clusters and spatial outliers map for local spatial autocorrelation analysis of scorpion sting incidence from 2000 to 2019. Blue (respectively red, pink, light blue, gray) corresponds to low-low (respectively high-high, high-low, low-high, not significant) clusters|
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| Discussion|| |
Scorpion envenomation is still a major public health problem in some parts of the world and an emergency medical for children and the elderly. Algeria is not spared by this issue; nearly 50,000 stings and 50 deaths are reported every year. The country houses a diverse scorpion fauna. At present, 46 species and subspecies are cataloged for the country, that is, 1.7% of the world's species inventoried by zoologists. They belong to 14 genera and three families (Buthidae, Euscorpiidae, and Scorpionidae). The dangerous scorpion species to humans are Androctonus australis (south highlands, Saharan Atlas), Buthus occitanus tunetanus (Septentrional edge of the Sahara), Androctonus Aeneas (highlands, Saharan Atlas), and Androctonus Crassicauda (Tindouf). It should be noted that huge gaps exist in the knowledge of this fauna in the north of the country.,,
Thirty years ago, scorpion stings represented only an issue in high plateaus and Sahara Desert. The number of provinces recording scorpion stings has increased from 27 provinces in 2000-45 in 2019, an increase of 66.7%. At present, only three Northern provinces are spared from this issue. As 2019, sixteen provinces of highlands and Sahara had more than 1000 scorpion sting cases and alone accounted for 90% of stings and 90% of deaths. The mean incidence was estimated at 137 scorpion stings per 100,000 inhabitants and the mean lethality was estimated at 0.18.
Scorpion stings are not always fatal; dangerous species can cause death in a limited number of people through timely management. The number of deaths fell from 149 in 1999 to 38 in 2019 thanks to an improvement in the management of this issue.
Regarding the repercussions of coronavirus disease (COVID-19) pandemic, it should be noted that over the past 2 years 2020 and 2021, the number of stings and deaths dropped; however, there is no evidence that the drop is attributable to the pandemic.
Epidemiological and statistical approaches, using surveillance data, carried out in Algeria concerned only some provinces recording high number of stings.,,,,,,, Geospatial analytical methods are basic to enhance our understanding of public health issues. A growing number of studies have used geospatial analytical methods to analyze disease trends and to detect spatial clusters. Studies on clustering have been undertaken in Algeria to identify tuberculosis (TB) spatial clusters, in Guangxi Zhuang autonomous region in China to determine spatial and temporal pattern of TB transmission, in Uganda to identify areas where both TB and HIV disease co-cluster.,, Our literature review found no studies conducted on spatial clustering of scorpion envenomations in Algeria. The purpose of this retrospective study was to bring word on the trend, spatial distribution, and spatial clustering of scorpion envenomations in the country.
The global and local Moran's indexes were used to investigate the geographical clustering patterns of scorpion stings. Significant hot spots were identified in the Sahara region and the high plateaus region.
Although this study met its stated goals, there are some limitations. First, data are stored at the province level which represents a broad aggregate level. The findings can be more relevant and informative if the spatial analysis is performed at the municipality level, a finer geographical level. Second, some potential risk factors data, such socioeconomic, environmental factors, and climate factors which may be related to clustering, were not included due to nonavailability of such data.
Since the creation of the National Committee of Control of Scorpion envenomation (CNLES) in 1986, several steps have been taken to deal with this problem. However, the surveillance of scorpion envenomation is based on a passive system; the notification of cases, the supply of treatment and care as well as awareness campaigns are the main actions carried out by the health authorities. Moreover, the ideal environmental conditions for the proliferation of the scorpions are brought together in highlands and Sahara. Indeed, the man increases the possibilities of contact with the scorpion via the extension of villages and towns without sanitation of land, creating perfect biotopes close to homes. Given the expansion of scorpion envenomation to almost the entire country, there is a need to reframe the set objectives and the actions to be carried out taking into account spatial clustering, seasonality, and species spatial distribution and also to define alternative policies to avoid sting accidents rather than accepting them as inevitable. Further research and investigation and multidisciplinary scientific collaboration are called for. As the human bear a great responsibility in sting accidents through its negligence and sometimes its ignorance, a good management can be achieved, not only by mere information campaigns, but also by an active public participation at all levels of planning, decision-making, implementation, monitoring, and evaluation, and this over the long term while taking into consideration the environmental, social and economic factors.
No ethical permission for TB data was required for this retrospective study; the statutorily collected data were anonymized.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3]