Chronic Musculoskeletal Disabilities following Snake Envenoming in Sri Lanka: A Population-Based Study

Abstract

Background: Snakebite is a major public health problem in agricultural communities in the tropics leading to acute local and systemic impairments with resultant disabilities. Snakebite related long-term musculoskeletal disabilities have been a neglected area of research. We conducted a population-based, cross-sectional study in an agricultural community to describe the chronic musculoskeletal disabilities of snake envenoming.

Methodology/principal findings: A sample representative of residents of a single district in a region of high incidence of snake envenoming was recruited to identify ever snakebite victims. They were evaluated for chronic musculoskeletal disabilities that had developed immediately or within four weeks after the snakebite and persisted over three months. In-depth interviews, validated musculoskeletal functional assessment criteria and specialists' examinations were utilised. Among the 816 victims, 26 (3.2%, 95% confidence interval: 2.2-4.6%) had musculoskeletal disabilities, persisting on average for 13.4 years (SD = 14.4). The disabilities were mostly in lower limbs (61.5%) and ranged from swelling (34.6%), muscle wasting (46.1%), reduced motion (61.5%), reduced muscle power (50%), impaired balance (26.9%), chronic non-healing ulcers (3.85%), abnormal gait (3.85%), fixed deformities (19.2%) to amputations (15.4%). Based on disability patterns, six snakebite-related musculoskeletal syndromes were recognised. The offending snakes causing disabilities were cobra (30.8%), Russell's viper (26.9%) and hump-nosed viper (7.7%). Cobra bites manifested muscle wasting (87.5%), reduced muscle power (87.5%), joint stiffness (62.5%) and deformities (37.5%) while viper bites manifested impaired balance (42.8%), pain (71.4%) and swelling (71.4%).

Conclusions/significance: Snakebite envenoming is associated with considerable long-term musculoskeletal disabilities. Facilities for specialized care and rehabilitation need to be established in high risk areas.

Fig 1. Distribution of the snakebite victims according to their presenting clinical symptoms.

Fig 2. Wasting of right quadriceps muscles (A) and wasting of right calf muscles (B) following cobra bite.

Fig 3. Chronic non-healing ulcer of the right foot and fixed deformities of toes following cobra bite.

Fig 4. Persistent lump over the lateral malleolus (arrow) following viper bite.

Fig 5. Fixed finger deformities in the left hand following snakebite.

Fig 6. Amputation of the right index finger following cobra bite.