Epidemiological survey of accidents with venomous animals treated at the Regional Hospital of Bom Jesus, Piauí, Northeast Brazil

INTRODUCTION

Venomous animals are all those that possess structures such as glands or pouches that produce venom (poison)^[1,2], which is delivered through modified teeth, stingers, or chelicerae^[3]. The main venomous animals responsible for causing accidents in humans and, therefore, of medical interest in Brazil are species of snakes, scorpions, spiders, moths, bees, wasps, some species of fish, caterpillars, and ants^[4].

These animals are considered the second cause of human poisoning after drug use and are responsible for 26.8% of all human intoxications recorded in Brazil^[5,6]. Cases involving snakes, scorpions, and spiders are the most prevalent, followed by intoxications caused by other species^[7,8]. Due to the high number of recorded occurrences and the severity of the cases^[7,9-12], accidents with venomous animals reflect serious economic, medical and social public health problems in tropical countries. The significant lethality and ability to cause temporary or permanent disability, or even death, along with the difficulty in accessing health units and the scarcity of antivenom for treatment^[13,14], further underscore the critical importance of this condition in the country. According to data provided by the National Notifiable Diseases Information System (SINAN) from the Brazilian Ministry of Health, there were 1,180,844 accidents by snakes, the same number for spiders, 521,977 for scorpions, and 79,580 for bees from 1975 to 2015. These data confirm the importance of epidemiological surveillance of accidents involving venomous animals for public health in Brazil^[15].

The Hospital Regional Manoel de Souza is located in Piaui State, northeast of Brazil, between savanna and Caatinga biomes (latitude 09°04’ south and longitude 44°21’ west). Piaui is characterized as an agrarian pole, and currently, approximately 430 thousand hectares are cultivated with grains such as soybean, rice, and corn^[16]. Considered the last agricultural frontier of Brazil, the pressure exerted on the environment has caused numerous changes in the landscape, thus exposing the human population to the risk of harm, such as accidents by venomous animals. Moreover, the accidents have been intensified by the absence of adequate urban planning and overlapping use of space for animals and humans^[17]. This descriptive study aims to describe the venomous animal-related accidents in humans treated at the Regional Public Hospital of Piaui and to analyze the temporal and spatial distribution of these incidents from 2009 to 2017.

METHODS

Study area and data collection

The notification forms registered in SINAN were provided by the Epidemiology sector of the Hospital Regional Manoel de Souza in Bom Jesus, PI, from July 2009 to December 2017. The Hospital is responsible for treating cases of accidents by venomous animals from 18 municipalities in the south of the state: Alvorada do Gurguéia, Avelino Lopes, Baixa Grande do Ribeiro, Bom Jesus, Brejo do Piaui, Cristino Castro, Currais, Gilbués, Júlio Borges, Manoel Emidio, Monte Alegre do Piauí, Morro Cabeça no Tempo, Palmeira do Piaui, Parnaguá, Redenção do Gurguéia, Santa Filomena, Santa Luz, and Uruçuí [Figure 1].

Figure 1. Location of the study area.

All these cities, according to Brazilian Institute of Geography and Statistics (IBGE) data, have the predominance of the population in the rural area and the main economic activity is family agriculture in the Caatinga area and soy, bean, and corn plantations in the Brazilian savanna [Figure 2]. The weather is characterized by distinct seasons, with dry winters and rainy summers. The average maximum temperature reaches 38 °C, while the minimum averages 24 °C. The dry period typically lasts up to six months, from May to September^[18]. According to the Köppen climate classification^[19,20] the climate of the study area falls into the Aw type.

Figure 2. Land use and occupation in the municipality of Bom Jesus - PI, from 2009 to 2017. The data for building this map were taken from the MapBiomas platform (https://brasil.mapbiomas.org/).

RESULTS

In the period between 2009 and 2017, 833 cases of accidents caused by venomous animals treated at the Hospital Regional Estadual Manoel de Sousa Santos were reported to SINAN. In 2010, there was a lower incidence, with 3.1 cases per 10,000 inhabitants. However, there was a notable trend of 68% growth in cases over the study period [Figure 3].

Figure 3. Incidence of accidents with venomous animals reported at Hospital Regional Manoel de Sousa Santos, Bom Jesus - PI, from 2009 to 2017.

During the course of the year, accidents were concentrated in the rainy season, with a tendency of increasing incidence over the years of rainy seasons [Figure 4].

Figure 4. Monthly incidence/10,000 inhabitants of accidents by venomous animals reported at Hospital Regional Manoel de Souza, Bom Jesus - PI, from 2009 to 2017.

Accidents by scorpions were the most frequent, accounting for 69.7% (n = 269) of the cases, followed by snakes (17.6%; n = 68) and insects (12.7%; n = 49). Although the Regional Hospital is rightfully responsible for providing assistance to only seven municipalities, it extends its coverage to 12 municipalities nearby. Bom Jesus City reported the highest occurrence (57%; n = 459).

While there was a 42% decrease in accidents caused by snakes over the years during the study [Figure 5], there was a distinct trend of scorpion-related accidents increasing by 70% [Figure 6].

Figure 5. Annual distribution of accidents by venomous snakes reported at the Manoel de Souza Regional Hospital, Bom Jesus - PI, from 2009 to 2017, and annual incidence/10,000 inhabitants.

Figure 6. Annual distribution of accidents caused by scorpions reported at the Manoel de Souza Regional Hospital, Bom Jesus - PI, from 2009 to 2017, and annual incidence/10,000 inhabitants.

The people most affected by venomous animals were men (53.9%; n = 208) among the age groups from 20 to 39 years (42.5%; n = 164) [Table 1]. Professionals who practiced activities in closed environments were the most attacked (57%; n = 220) [Table 1]. However, specifically for snakes, professionals with activities in closed places were the least exposed to accidents (B = -1,302, OR = 0,568. 95%CI = 0,272, 0,130) and those between adolescents 10 and 19 were more likely to be injured by a snakebite (B = 1,526, OR = 4,598, 95%CI = 1,460, 14,474). Hospital care for victims occurred predominantly until the first 3 h of the accident (68.6%, n = 464). The patients demonstrated local pain with or without paresthesia, with most cases classified as mild.

About 50.3% (n = 194) of the victims showed systemic manifestations, including neuroparalytic symptoms (11.2%, n = 50) and vasovagal syncope (8%; n = 36). Regarding treatment, 87.2% of those affected required specific serum therapy, with 97.2% of cases of accidents involving scorpions (n = 317) recovered [Table 1].

The most frequent bite site was on the extremities, with the feet being the most affected region, accounting for 39.3% (n = 235), followed by the hands at 25.8% (n = 154) and the legs at 8% (n = 48) [Figure 7]. A total of 96.4% (n = 372) presented local manifestation, with the most reported symptoms by victims being pain (50.5%, n = 522) and edema (43.4%, n = 448). Despite the detailed nature of the SINAN forms, it was possible to identify errors or omissions in the completion of the forms. For example, 51.1% of cases were omitted in the variable serum therapy.

Figure 7. Frequency of accidents by venomous animals according to the site of the bite on the body and animal species reported at the Regional Hospital Manoel de Souza, Bom Jesus - PI, from 2009 to 2017.

DISCUSSION AND CONCLUSION

In the present work, the greatest difficulties lay in the organization of the monthly and annual service records, as well as in understanding them due to poor handwriting and incomplete information. In this study, it was observed that most accidents were caused by scorpions, followed by snakes. Likewise, two different studies conducted by Cantinho et al. from 2007 to 2014 and by Benício et al. from 1999 to 2010 on accidents across different regions of the State of Piauí, revealed a remarkable incidence of scorpion-related accidents, followed by snakes^[21,22]. In a study in the city of Palmas, Brazil, it was also observed a higher frequency of reported accidents caused by scorpions and snakes^[23]. We believe that different types of habitats support a diversity of venomous animal species, many of which hold significant medical importance.

Data from the Ministry of Health indicate the occurrence of approximately 8,000 accidents by scorpions per year, with an incidence coefficient of approximately three cases/100,000 inhabitants. Consistent with the findings in the present study, other reports also show a high number of scorpion accidents recorded in Brazil^[24-26]. These incidents are frequent as scorpions have adapted quite well to urban environments and the conditions provided by housing. The urbanization process has created environments conducive to their survival, including shelter possibilities such as garbage and rubble, consequently leading to a plentiful diet due to the presence of cockroaches and other insects^[11,27,28]. Ecological imbalances and human activities, such as disorderly urban growth, poor sanitary conditions and replacement of vegetation for the implantation of new subdivisions or plantations, as evidenced in the use of land occupation in Piaui, may be one of the possible explanations for the trend of increasing cases in the study period.

Differently from what was found in the present study, Parise found that in more than 50% of the cases, the time elapsed between the accident and the care was less than 1 h, and in 25.82%, between 1 and 3 h^[23]. The urgency of care is extremely important, as it is directly related to a lower severity of the case or a good prognosis^[29]. The longer arrival time at the hospital mentioned in the present study can be attributed to the fact that this regional hospital is the sole provider of such specialized care. Therefore, we suggest that population awareness measures be taken to reduce this arrival time.

Regarding seasonality, there was a predominant increase in accidents by venomous animals in the rainy season. Some studies commented that the highest occurrence of accidents is related to higher temperatures and not greater rainfall^[29].

In agreement with several other studies, the predominance of male accidents was observed. One such study analyzed the epidemiology of venomous animal accidents that occurred in the last 100 years in Brazil^[8], revealing that the most affected population comprises male rural workers. Similar findings have been reported elsewhere in Brazil, with over 60% of the accidents occurring in males^{[11,23,30-33]}, which may be directly linked to work activities. The early engagement of these individuals in agricultural labor, most likely aimed at augmenting family income, is evident, as corroborated by the present work^[34-36].

As observed in previous studies, the present study also revealed a high rate of bites on the lower limbs, especially on the feet, as the most commonly affected areas by these animals^[23,24,37]. The anatomical site of a scorpion sting significantly impacts the severity of the accident, as proximity to vital organs correlates with increased complications and sequelae of the accident^[38]. The species of scorpions and the amount of venom are also risk factors for the classification of cases. However, it was observed that there is no reference to the species of aggressor scorpion in the SINAN form. We therefore recommend amending the form and including this information, along with providing training to the agents responsible for completing it, enabling them to identify the venomous animals prevalent in the region.

Local clinical manifestations such as pain and edema were very common and verified by several studies^[39]. The most effective treatment for scorpion accidents is the administration of anti-scorpion serum. Upon analyzing the results of serum therapy, it was noted that the administration of serum occurred in 87.2% of the cases. The use of serum for scorpion stings should only be administered to patients classified as moderate and severe, who present systemic manifestations or other symptoms beyond pain, swelling, and local paresthesia such as numbness or tingling. The amount to be applied directly depends on the medical diagnosis that must be made for each type of accident, evaluating the clinical manifestations presented by the individual and laboratory tests. This is in line with what was observed in this study, in which most patients required specific serum therapy, depending on the aggressor animal.

The study showed that Piaui is an area with a high incidence of accidents by venomous animals, mainly scorpions. Therefore, this investigation is a starting point for understanding the spatial distribution of these accidents. The data show that there are still gaps in the flow of information from SINAN and that the number of accidents is increasing. Therefore, it is imperative to facilitate and conduct educational initiatives aimed at enhancing the accuracy of official data records, so that they can be incorporated into the care routine. Given the frequency and severity of these accidents, as well as the necessity for comprehensive data collection (including precise location and demographic information of affected populations), this effort is crucial for improving patient prognoses.