EPIDEMIOLOGICAL AND CLINICAL ASPECTS OF SNAKEBITES IN BOLIVAR STATE, VENEZUELA
A Caraballo¹, J Navarro², E Sánchez³, JC Pérez4 and A Rodríguez-Acosta5.
¹ Profesor Agregado. Universidad de Oriente, Facultad de Medicina, Ciudad Bolívar, Venezuela.- ²Médico Consultante. Medicatura Rural Aguasay, Estado Monagas, Venezuela.- ³Jefe de Laboratorio. Natural Toxins Research Center, Texas A&M University-Kingsville, Texas, USA.- 4 Regents Professor. Director Natural Toxins Research Center, Texas A&M University-Kingsville, Texas, USA.- 5 Profesor Titular. Instituto de Medicina Tropical de la Universidad Central de Venezuela, Caracas, Venezuela.E-mail: rodriguf@ucv.es
RESUMEN: Se estudia retrospectivamente los aspectos clínicos y epidemiológicos de los pacientes con mordeduras de serpientes en el Estado Bolívar, Venezuela. Se revisaron los expedientes de 284 pacientes del Hospital Universitario Ruiz y Páez en Ciudad Bolívar, Venezuela desde enero 1990 hasta diciembre 1999 que sufrieron mordeduras de serpientes. La mayoría de estos pacientes fueron trabajadores rurales, 155 (76.4) hombres y 48 (23.6%) mujeres, con edades entre un año y mayores de sesenta años. Ciento cuatro (51.7%) pacientes fueron mordidos por serpientes del genero Bothrops, 75 (37.0%) por Crotalus y 23 (11.3%) por Lachesis. Ciento veinticuatro (86.2%) fueron mordidos en las piernas y 28 (13.8%) en el brazo. De enero a noviembre fueron los meses de mayor incidencia de envenenamientos botrópicos, mientras los envenenamientos crotálicos fueron de junio a diciembre. Los envenenamientos lachésicos fueron de octubre a diciembre. Este estudio mostró que la prevalencia de envenenamientos crotálicos en el estado Bolívar fue más elevado que en otra región de Venezuela. Promover estudios epidemiológicos prospectivos será necesario para una mejor comprensión de estas conclusiones.
Palabras Clave: Mordeduras de serpientes, Envenenamiento ofídico, Accidente crotálicos, Accidentes bothrópicos, Accidentes lachesicos, Venezuela.
ABSTRACT: A retrospective study of the clinical and epidemiological aspects of snakebites in the Bolivar State, Venezuela, from January 1990 to December 1999 was done for 284 patients from the University Hospital Ruiz y Paez, in Bolivar City, Venezuela. Most of the patients were rural workers, 155 (76.4%) males and 48 (23.6%) females, from one to sixty years old. One hundred and five (51.7%) patients were diagnosed as bitten by Bothrops snakes; 75 (37.0%) by Crotalus, and 23 (11.3%) by Lachesis. One hundred seventy five (86.2%) were bitten in the legs and 28 (13.8%) in the arms. The high incidence of bothropic envenomation was from January to November, while crotalic envenomation was from June to December. Lachesic envenomation was from October to December. This study showed that the prevalence of crotalic envenomation in Bolivar State was higher than other regions of the country. Further prospective epidemiological studies will be necessary for a better understanding of these findings.
Key Words: snakebites, ophidic envenomation, crotalic accident, bothropic accident, Lachesic accident, Venezuela.
Fecha de Recepción: 15/10/2003 Fecha de Aprobación: 13/04/2004
INTRODUCTION
]]> Snakebite envenomation is a worldwide problem, especially in tropical regions(2-8,31) Annual incidence rates may vary according to geographical regions, from 4.8-125.7/10,000 in West Africa and 0.3-8.2/10,000 in New Guinea, to 1.4/10,000 in Brazil and 0.3/10,000 in the United States(9-13). Most of the snakebite cases presented in the Western hemisphere are due to the Viperidae family also known as pit vipers. In South America, Viperidae are represented by Bothrops (now subdivided into a number of new genera), Crotalus and Lachesis genera(14-17).Since 1961, very few studies on the clinical and therapeutics on the snakebites in the Guayana region have been conducted(1). Thus, the main focus of the present work was to study the actual epidemiological and clinical situation of snakebites in Bolivar State, Venezuela.
PATIENTS AND METHODS
A retrospective survey of all patients bitten by venomous snakes who were admitted to the University Hospital «Ruiz y Paez», Bolivar City, southeast Venezuela, from January 1990 to December 1999 was carried out. This hospital is a reference hospital for a large area of the state and neighbouring states. The majority of severe cases are referred to this hospital because antivenom, intensive care and dialysis facilities are available. Distribution of cases in time, place, sex, age, occupation, site of bite, month when the bite occurred, time delay in reaching the hospital and the species of the offending snake were based on the epidemiological hospital records. Diagnosis was made on snake identification, when this was brought by the patient and/or by clinical manifestations. Statistic was performed using the EPI-INFO software package (Centers for Disease Control, Atlanta, GA and the World Health Organization, Geneva, Switzerland).
RESULTS
Records from 203 cases were studied. Patients came from 11 Bolivar state municipalities. Sixty-two percent of the cases came from Raul Leoni municipality. The majority of the bites (58.1%) occurred between 12:00 am and 6:00 pm. Seventy-six percent of the patients were male. Fifty-two percent were bitten by Bothrops snakes, 37.0% by Crotalus and 11.3% by Lachesis, (Table 1).
| Table 1 Distribution of patients by gender | ||||||
| ]]> Genera | Patient sex |
| ||||
| Males | Females | Total | ||||
| Nº | % | Nº | % | ]]> Nº | % | |
| Bothrops Crotalus Lachesis Total | 77 58 20 155 | ]]>
37.9 28.6 9.9 76.4 | 28 17 3 48 | 13.8 8.4 ]]> 1.423.6 | 105 75 23 203 | 51.7 37.0 11.3 100.0 |
| Table 2 Distribution of patients by age | ||||||
| Age (years) | Snake Genera | |||||
| Bothrops | Crotalus | ]]> Lachesis | ||||
| Nº | % | Nº | % | Nº | % | |
| 0-10 11-20 21-30 ]]> 31-4041-50 51-60 >60 Total | 14 26 21 13 22 ]]> 36 105 | 6.9 11.9 10.4 6.4 11.0 1.4 2.8 ]]> 52.0 | 12 19 15 6 7 10 6 75 | 5.9 ]]> 9.47.4 3.0 3.4 4.9 3.0 37.0 | 5 4 3 ]]> 33 4 1 23 | 2.7 2.0 1.4 1.4 1.4 ]]> 2.00.4 11.0 |
In 190 cases (93.5%), the snake was captured and identified as B. colombiensis (52 cases), B. atrox (46 cases); C. durissus (70 cases) and L. muta muta (22 cases). Thirteen (6.4%) cases were diagnosed by clinical findings. Legs were the most common site of bites (86.2%), (Table 3).
| Table 3 DISTRIBUTION OF AFFECTED SITES | ||||||
| Site of bite | Snake Genera | |||||
| ]]> Bothrops | Crotalus | Lachesis | ||||
| Nº | % | Nº | % | Nº | % | |
| Legs ]]> AmsTotal | 93 12 105 | 45.8 5.9 51.7 | 59 16 ]]> 75 | 29.1 7.9 37.0 | 23 - 23 | 11.3 - 11.3 |
The time interval between the bite and admission to the hospital ranged was less than 6 hours in 68.5% of the cases (Table 4). The distribution of the patients according to the severity of the envenomation and the species of the snakes is shown in Table 5.
| Table 4 time elapsed between ophidic accidentS and medical treatment | ||||||
| Time | Snake Genera | |||||
| Bothrops | Crotalus | ]]> Lachesis | ||||
| Nº | % | Nº | % | Nº | % | |
| Under 6 hr After 6 hr Unknown ]]> Total | 69 24 12 105 | 34.0 11.8 5.9 51.7 | 57 ]]> 117 75 | 28.1 5.4 3.5 37.0 | 13 6 4 ]]> 23 | 6.4 3.0 4.9 11.3 |
| Table 5 DISTRIBUTION OF PATIENTS BY SEVERITY OF ENVENOMATION | ||||||
| ]]> Severity | Snake Genera | |||||
| Bothrops | Crotalus | Lachesis | ||||
| Nº | % | Nº | % | Nº | ]]> % | |
| Mild Moderate Severe Total | 89 12 4 105 | 43.9 ]]> 6.02.0 51.9 | 63 9 3 75 | 31.0 4.4 1.4 ]]> 36.8 | 20 2 1 23 | 9.9 1.0 0.4 11.3 |
Most of the patients were rural workers (57 %), students (15.1%), miners (14.8%), unknown (9.9%) and housekeepers (8.5 %), (Table 6).
]]>| Table 6 Distribution of snakebites according to occupation | ||||||
| Occupations | Snake Genera | |||||
| Bothrops | Crotalus | Lachesis | ||||
| Nº | ]]> % | Nº | % | Nº | % | |
| Rural workers Miners Students Housekeepers Unknown | ]]>
49 20 17 10 9 | 23.3 9.8 8.3 5.0 4.5 | ]]>
44 5 12 6 8 | 21.7 2.5 509 3.0 3.9 | ]]>
12 5 2 1 3 | 5.9 2.5 0.9 0.5 1.5 |
| Table 7 distribution of Monthly snakebite occurrences (1999) | ||||||||||||
|
| Jan | Feb | Mar | Apr | ]]> May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
| Bothrops Crotalus ]]> Lachesisi | 10 8 3 | 7 2 4 | 13 8 2 | ]]>
4 3 0 | 7 2 1 | 12 7 1 | 12 ]]> 82 | 10 7 2 | 12 12 1 | 7 6 ]]> 4 | 7 3 2 | 4 9 1 |
DISCUSSION
The University Hospital «Ruiz y Paez» had admitted cases of snakebites from many municipalities of the Bolivar and neighbouring states in Venezuela. Some of these cases were referred because they presented from moderate to severe symptoms, requiring special care. In Venezuela, the official notification of envenomation cases became obligatory. Currently, there is antivenom available for early treatment in several health centers of Bolívar state. Early administration of antivenom proved to be effective in terms of better evolution and patient prognosis(18,19), as it was observed in this study
The distribution of cases by age, sex, time of day and anatomical site was consistent with other studies(3-5,8,12,15,18,19,25,27-29).
]]> 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 are bitten in the legs(6,12,20,21,22). Crotalic envenomations were considered moderate to severe when compared with bothropic envenomations. These results agree with those found in the literature(12,18,20,21,23).In Bolivar State, the prevalence of crotalic envenomations was higher, when compared with other regions of Venezuela.
Bolivar State is a tropical region 264.000 km2 in area situated at 8º 15' N, 61º 10' W. A. Tropical rainforest climate prevails, with an average annual precipitation of 1,400 mm, 26ºC mean temperature, a relative humidity of 80%, and altitudes until 1,200 meters. Most patients bitten by venomous snakes (14.8%) working in the patchy forest areas where associated with gold and diamond miners. The epidemiological problems may arise when forests are cleared and cultivated for commercial tree plantations which, produces changes in abundance and behaviour of snakebites(11).
Bolivar state economy and geography, in addition to the environment may contribute to the procreation of snakes of the genus Bothrops and Crotalus. An interesting finding was the high incidence of Crotalus accidents that it is infrequent in the rest of the Country. Prospective epidemiological studies will be needed for a better understanding of these findings.
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