HUMAN ENVENOMATIONS DUE TO SNAKEBITES IN MARILIA, STATE OF SÃO PAULO, BRAZIL. A RETROSPECTIVE EPIDEMIOLOGICAL STUDY

Original paper

HUMAN ENVENOMATIONS DUE TO SNAKEBITES IN MARILIA, STATE OF SÃO PAULO, BRAZIL. A RETROSPECTIVE EPIDEMIOLOGICAL STUDY.

L.P.S. SGARBI

, M. ILIAS , T. MACHADO , L. ALVAREZ , B. BARRAVIERA ^2,3.

1 Department of Internal Medicine of the School of Medicine of Marília, State of São Paulo, Brazil; 2 Department of Tropical Diseases of the School of Medicine of Botucatu - UNESP, State of São Paulo, Brazil; 3 Center for the Study of Venoms and Venomous Animals - CEVAP - UNESP, State of São Paulo, Brazil.

ABSTRACT. Eighty-four patients bitten by venomous snakes were studied retrospectively at the School of Medicine of Marilia from January 1990 to August 1994. The majority of these patients were rural workers, 65 (77.38%) males and 19 (22.62%) females, aged eight to seventy-five. Forty-three (51.19%) patients were diagnosed as having been bitten by snakes of the genus Bothrops and 41 (48.81%) by Crotalus. Fifty-eight patients (69.04%) were bitten in the legs and 26 (30.96%) in the arms. January, March, April and November were the months of higher incidence of bothropic envenomations, while crotalic envenomations were not recorded only in August and September. This study showed that the prevalence of crotalic envenomations in Marilia was higher than that of any other regions in Brazil. Further prospective epidemiological studies are needed for a better understanding of these findings.

KEY WORDS: envenomations, Bothrops snakes, Crotalus snakes, retrospective epidemiological study.

INTRODUCTION

Envenomation caused by snakebite is an important public health problem in tropical countries due to its high incidence, severity and frequent sequelae (2,4,5,6,13). In Brasil, notification of envenomation cases has become obligatory since 1986(6). Nowadays, around 20,000 cases are registered each year, with 2,000 of them from the State of São Paulo(8). Bothropic envenomations account for 85% to 90% of the cases, while crotalic for 8% to 15%. Envenomations by Micrurus and Lachesis are rare in the State of São Paulo(6,8). Some authors (2,3,4,6,8) have pointed out the variation of the prevalence of envenomation cases in different regions of São Paulo. Thus, the objective of the present work was to study the distribution of envenomation cases in Marilia and compare them with those of other regions in Brazil.

PATIENTS AND METHODS

Eighty-four patients bitten by venomous snakes in Marilia, who received medical care at the Internal Medicine Clinic of the School of Medicine of Marilia from January 1990 to August 1994, had their epidemiological records analyzed. The following data were studied: sex, age, occupation, site of bite, month when the bite occurred, time delay in reaching the hospital and the species of the offending snake. Diagnosis was made based on snake identification, when this was brought by the patient, and/or by clinical manifestations.

RESULTS

Of the 84 patients studied, 65 (77.38%) were males and 19 (22.62%) females as shown in Table 1. Table 2 shows that 41 individuals (48.81%) were bitten by snakes of the genus Crotalus and 43 (51.19%) by Bothrops. Table 2 also shows that 54 (64.28%) patients were between 16 to 50 years of age. Table 3 shows that the majority of the patients were bitten in the legs (69.04%). The time elapsed between the bite and the arrival at the hospital was less than 6 hours in 82.14% of cases, as show in Table 4. Table 5 shows the distribution of the patients according to the severity of the envenomations and the species of the snakes. Most of the patients were rural workers (58.33%) as shown in Table 6. January, March, April and November were the months of higher incidence of bothropic envenomations, while crotalic envenomations were not recorded only in August and September, as shown in Figure 1.

TABLE 1.
Patients bitten by venomous snakes according to sex and genus of the snakes.

TABLE 2.
Patients bitten by venomous snakes according to age and genus of the snakes.

TABLE 3.
Patients bitten by venomous snakes according to site of bite and genus of the snakes.

TABLE 4.
Patients bitten by venomous snakes according to the time elapsed between the envenomation, medical care and genus of the snakes.

TABLE 5
. Patients bitten by venomous snakes according to the severity of envenomation and genus of the snakes.

TABLE 6.
Patients bitten by venomous snakes according to the patients occupations and genus of the snakes.

FIGURE 1.
Patients bitten by venomous snakes according to the months of the occurence.

DISCUSSION

In the early 1980s, Brazil underwent the worst "crisis of lack of antivenom"(6). From 1986 on, notification of envenomation cases became obligatory in the country(6,8). Then, it was possible to know, at least in part, the real demand for antivenom for a one-year period. Currently, there is antivenom available for early treatment in Marilia. In addition, the State Government has set up several strategically located Health Care Centers to provide medical attention to snakebite victims in Marilia and nearby regions (11,12). Early administration of antivenom proved to be effective in terms of the patients better course and prognosis, as it was observed in this study(9,10).

The results showed that snakebites were more frequent among young rural workers at work, which allows us to classify them as "work accidents". According to the literature, most of the workers were bitten in the legs(4,6,8,11,12). Crotalic envenomations were considered severe when compared with bothropic envenomations. These results agree with those in the literature(4,6,8,10,11).

Nowadays, about 20,000 envenomation cases are reported in Brazil each year, 2,000 of them from the State of São Paulo(8). Of the latter, around 85% of the cases are caused by snakes of the genus Bothrops and 15% by Crotalus. Some authors(1,2,3,4,8) have reported the variation of the prevalence of envenomations regarding the different regions of the State of São Paulo. Thus, of the cases reported in Botucatu, State of São Paulo, around 80% are caused by snakes of the genus Bothrops and 20% by Crotalus(3,4).

In Marilia, the prevalence of crotalic envenomations was higher, when compared with that of other regions in Brazil. The Internal Medicine Clinic of the School of Medicine of Marilia is considered a very important referral emergency care for urban and rural Marilia. The town of Marilia is located 515 kilometers from the State capital, city of São Paulo, in the west central São Paulo State. Marilia lies between the Aguapeí and Peixe rivers(7) in the highlands at 652 m above sea level. It has a tropical climate with an annual rainfall of 1319 mm. The towns main economic activities are livestock raising as well as peanut, fruit, cotton, rice and coffee production and processing. Most of the crotalic envenomations occurred in June and November, months which coincide with the harvest of coffee and peanuts, respectively.

In conclusion, Marilia's economy and geography, in addition to environmental problems may have contributed to the procreation of snakes of the genus Crotalus. Consequently, the incidence of crotalic envenomations observed was higher, too. Prospective epidemiological studies will be needed for a better understanding of these findings.

• 01 AZEVEDO-MARQUES MM., CUPO P., HERING SE. Acidentes por animais peçonhentos. Medicina, 1992, 25, 539-54.
• 02 BARRAVIERA B., PEREIRA PCM. Acidentes por serpentes dos gêneros Bothrops, Lachesis e Micrurus Arq. Bras. Med., 1991, 4, 345-55.
• 03 BARRAVIERA B., BONJORNO Jr JC., ARAKAKI D., DOMINGUES MAC., PEREIRA PCM., MENDES RP., MARCONDES-MACHADO J., MEIRA DA. A restrospective study of 40 victims of Crotalus snake bites. Analysis of the hepatic necrosis observed in one patient. Rev. Soc. Bras. Med. Trop., 1989, 22, 5-12.
• 04 BARRAVIERA B., GARCIA FCM., FULINI DR., MARCONDES-MACHADO J., MENDES RP., PEREIRA PCM., SOUZA LR., ZORNOFF DCM., MEIRA DA. Estudo clínico-epidemiológico de doentes picados por serpentes venenosas na região de Botucatu - SP. J. Bras. Med., 1994, 67, 224-32.
• 05 BARRAVIERA B., LOMONTE B., TARKOWSKI A., HANSON LÅ., MEIRA DA. Acute-phase reactions, including cytokines, in patients bitten by Bothrops and Crotalus snakes in Brazil. J. Venom. Anim.Toxins, 1995, 1, 11-22.
• 06 BRASIL. Ministério da Saúde. Secretaria Nacional de Ações Básicas de Saúde. Acidentes ofídicos Brasilia, 1990 2p. (Contribuição para o estudo da morbidade, 47/48).
• 07 CORREIA-FILHO V. Enciclopédia dos municípios brasileiros São Paulo: IBGE, 1957, 29, 1253-5.
• 08 JORGE MT., RIBEIRO LA. Epidemiologia e quadro clínico do acidente por cascavel sul-americana, Crotalus durissus terrificus Rev. Inst. Med. Trop. São Paulo, 1992, 34, 347-54.
• 09 KOUYOUMDJIAN JA., POLIZELLI C. Acidentes ofídicos causados por Bothrops moojeni. Relato de 37 casos. Rev. Inst. Med.Trop.São Paulo, 1988, 30, 424-32.
• 10 RIBEIRO LA., JORGE MT. Epidemiologia e quadro clínico dos acidentes por serpentes Bothrops jararaca adultas e filhotes. Rev. Inst. Med. Trop. São Paulo, 1990, 32, 436-42.
• ¹¹
  11 RIBEIRO LA., PIRES DE CAMPOS VFA., ALBUQUERQUE MJ., TAKAOKA NY. Acidentes ofídicos no Estado de São Paulo. Rev. Assoc. Med. Bras., 1993, 39, 4-7.
• 12 SÃO PAULO. Secretaria de Estado da Saúde. Comissão Permanente de Coordenação para o Controle dos Acidentes por animais peçonhentos. Caracteres clínico-epidemiológicos dos acidentes ofídicos peçonhentos notificados no Estado de São Paulo em 1991. São Paulo, 1992 Não paginado (Boletim 1/92).
• 13 WORLD HEALTH ORGANIZATION. Progress in the characterization of venoms and standardization of antivenoms. W.H.O. Offset Publ., 1981, 58, 1-44.

CORRESPONDENCE TO:

L.P.S. SGARBI - Rua São Miguel, 361 - CEP 17.540-040 - Marilia - São Paulo - Brasil.

Publication Dates

• Publication in this collection
  08 Jan 1999
• Date of issue
  1995