Venom Proteomic Analysis of Two Medically Important Nigerian Viper (Echis Ocellatus and Bitis Arietans) Snake Species

Snakebite envenoming remains a neglected tropical disease, which poses severe health hazard, especially for the rural inhabitants in Africa. In Nigeria, vipers are the most toxin-producing snakes that cause the highest number of deaths. Hydrophilic interaction liquid chromatography coupled with LC-MS/MS was used to analyze the crude venom extracts of Echis ocellatus (Carpet viper) and Bitis arietans (Puff adder) in order to understand their venom proteomic identities. Results obtained revealed that gel-free proteomic analysis of the crude venom extracts from E. ocellatus and B. arietans yielded the identification of 85 and 79 proteins, respectively. Seventy-nine (79) proteins were common between the two snake species with a 90.8% similarity score. The identified proteins belong to 12 protein families where serine proteases (22.31%) and metalloproteinases (21.06%) were the dominant proteins in the venom of B. arietans. Metalloproteinases (34.84%), phospholipase A2s (25.69%) and serine proteases (17.25%) represents the major toxins in the E. ocellatus venom. Other protein families such as three-finger toxins and cysteine-rich venom proteins were also detected, albeit, in low proportions. This study represents the venom proteomic analysis of the two Nigerian viper species, which provides some valuable insights into the toxin families to be neutralized in case of envenomation. Data are available via ProteomeXchange with identifier PXD024638.

Acute transverse myelitis following carpet viper snakebite in Northeast Nigeria

Snakebite is a major cause of death and disability in developing countries. The common clinical features of snake envenomation include bleeding, acute kidney injury, dilated pupils and muscle paralysis resulting from the deleterious effects of venom toxins on human plasma proteins, cell membranes, muscle fibers and vascular endothelium. Snakes also harbour pathogenic organisms that may infect bite victims during envenomation, but few studies have described this phenomenon. We herein report a rare case of acute transverse myelitis occurring after snakebite in Northeast Nigeria, and discuss the possible role of bacteria and viruses after excluding other potential causes of myelopathy. This knowledge may help improve the care of snakebite victims among internists and emergency physicians.

Cytotoxiciy of Naja nubiae (Serpentes: Elapidae) and Echis ocellatus (Serpentes: Viperidae) Venoms from Sudan

In Sudan, as in many African countries, no local specific antivenom is manufactured resulting in snake bite victims being treated by antivenoms imported from abroad. In the present work we measured the cytotoxic effect of the recently described spitting cobra (Naja nubiae) and the carpet viper (Echis ocellatus) snake venoms using a cell based assay. We also investigated the efficacy of four antivenoms CSL (Australia), SAIMR (South Africa), snake venom antiserum (India), and EchiTAb-Plus-ICP (Cost Rica) to neutralize the cytotoxic effect of the two venoms. The venoms resulted in a remarkable inhibition of cell viability with N. nubiae being more cytotoxic than E. ocellatus. The four antivenoms studied were effective in neutralizing N. nubiae cytotoxicity. However, only partial efficacy in neutralizing the cytotoxic effect of E. ocellatus was achieved using CSL (Australia) and SVA (India) antivenoms. Based on the cross neutralization by the four antivenoms, the Sudanese N. nubiae venom most likely has homologous epitopes with similar snakes from Australia, South Africa, India, and Cost Rica, while E. ocellatus venom from Sudan shares little homology with similar snakes from other countries.

Bite-to-hospital time and morbidity in victims of viper bite in a rural hospital in Nigeria

Background: Mortality amongst in-hospital patients bitten by carpet viper in northern Nigeria has reduced, related to use of a monospecific ovine Fab snake antivenom. However, many victims survive with temporary or permanent morbidity. Objectives: Study objectives were to: (1) determine and score the morbidity caused by carpet viper bite; and (2) find the relationship between bite-to-hospital time and morbidity amongst victims of carpet viper bite.Method: A prospective study was conducted in a rural hospital in north-central Nigeria. The morbidities scored were oedema, tenderness, prolonged whole-blood clotting time, blister, ulcer, need for blood transfusion, coma, hypotension, convulsion, length of hospital stay, need for disarticulation, and need for skin graft. A score of one was given to each objective sign. The bite-to-hospital time of 233 subjects was obtained. Descriptive and inferential statistical analysis was done.Results: Most of the subjects (150 or 64%) came to the hospital within 6 hours of the snake bite, with 2 (1%) arriving within 1 hour. The median bite-to-hospital time was 5 hours, with a range of 0.5–216 hours. Major morbidities were oedema, seen in 212 (91.0%; 95% CI 86.6–94.3%); incoagulable blood, seen in 205 (88%; 95% CI 83.1–91.9%), and tenderness, seen in 201 (86.3%; 95% CI 81.2–90.4%). The mean morbidity score was 8 ± 4. For every unit increase in logged bite-to-hospital time, the morbidity score increased by 1.85 (p < 0.001).Conclusion: Morbidity caused by carpet viper bite is high in Zamko, north-central Nigeria, and correlates with increasing bite-to-hospital time.