South African Marine Envenomations and Poisonings as Managed Telephonically by the Tygerberg Poisons Information Centre: A 20-Year Retrospective Review.

INTRODUCTION: South Africa has an abundance of marine life, and the potential for hazardous exposure to marine life is high. To our knowledge, this is the first epidemiological review regarding marine toxicity that has ever been conducted in sub-Saharan Africa. The aim of this review was to investigate marine toxicology data as managed telephonically by the Tygerberg Poisons Information Centre. METHODS: Marine toxicology cases were retrospectively analyzed for a 20-y period (January 1, 1995 to December 31, 2014). Data were extracted from archived consultation forms. Descriptive statistics are presented, and post hoc analyses compared age, sex, province, and caller's background with severity and type of toxicology. RESULTS: A total of 311 calls involved 392 cases. Most calls involved adults (n=317, 81%) and males (n=214, 55%) and presented with no or minor symptoms (n=242, 62%). Poisoning from ingestion (n=239; 61%) was more commonly encountered than was marine envenomation (n=153; 39%), with paralytic shellfish poisoning (n=118; 30%), scombroid poisoning (n=93; 24%), and envenomation from stingrays (n=36; 9%) and bluebottles (n=33; 8%) occurring often. Healthcare professionals were more likely to consult for severe cases (odds ratio 3.3; 95% CI 1.9-5.9) and poisoning-related cases (odds ratio 1.8; 95% CI 1.1-2.9). CONCLUSION: The proportion of marine-related toxicology cases was low. Telephonic consultations by healthcare professionals relating to poisoning were generally of a serious nature. The data can be used to drive public health awareness campaigns.

The epidemiology and severity of scorpion envenoming in South Africa as managed by the Tygerberg Poisons Information Centre over a 10 year period.

INTRODUCTION: South Africa has a wide distribution of scorpion species, yet limited data are available regarding the incidence and severity of scorpion envenomation. The aim of this study was to analyse South African epidemiological data of scorpion stings and envenomation as reported to the Tygerberg Poisons Information Centre (TPIC). METHODS: A retrospective analysis was conducted of scorpion-related telephonic consultations to the TPIC over a ten year period (1 January 2005 to 31 December 2014). Data were entered onto a Microsoft Excel® spreadsheet and descriptive statistics are presented for all variables. Associations with severity of envenomation are presented as odds ratios (OR) with 95% confidence intervals (95%CI). RESULTS: During the study period 52,163 consultations were processed by the TPIC of which 740 (1.4%) cases involved scorpion stings. Of these, 146 (19.7%) cases were deemed serious envenomations. Antivenom was recommended to be administered in 131 (90%) of these cases. Healthcare professionals made most calls (63%), but were less likely to phone for non-serious cases (OR 0.16; 95%CI 0.09 to 0.29). The Western Cape Province had the highest incidence of calls (6.9 scorpion-related calls/100 000 people). Adults (>20 years) were victims in 71.4% of cases, and were more likely to experience less serious stings (OR 0.57; 95%CI 0.37 to 0.86). The TPIC was consulted within six hours of the sting occurring in 356 (48.1%) cases with a significant association to less severity (OR 3.51; 95%CI 1.9 to 6.3). Only 2% (15) of the scorpions were available for identification. CONCLUSION: The incidence of severe scorpionism to the TPIC was low. Care should be taken when children are involved and when calls are received more than six hours after the sting. TPIC consultants as well as healthcare professionals working in semi-arid regions should be aware of these high risk populations.

Purification, characterization and biosynthesis of parabutoxin 3, a component of Parabuthus transvaalicus venom.

A novel peptidyl inhibitor of voltage-gated K+ channels, named parabutoxin 3 (PBTx3), has been purified to homogeneity from the venom of Parabuthus transvaalicus. This scorpion toxin contains 37 residues, has a mass of 4274 Da and displays 41% identity with charybdotoxin (ChTx, also called 'alpha-KTx1.1'). PBTx3 is the tenth member (called 'alpha-KTx1.10') of subfamily 1 of K+ channel-blocking peptides known thus far. Electrophysiological experiments using Xenopus laevis oocytes indicate that PBTx3 is an inhibitor of Kv1 channels (Kv1.1, Kv1.2, Kv1.3), but has no detectable effects on Kir-type and ERG-type channels. The dissociation constants (Kd) for Kv1.1, Kv1.2 and Kv1.3 channels are, respectively, 79 microm, 547 nm and 492 nm. A synthetic gene encoding a PBTx3 homologue was designed and expressed as a fusion protein with the maltose-binding protein (MBP) in Escherichia coli. The recombinant protein was purified from the bacterial periplasm compartment using an amylose affinity resin column, followed by a gel filtration purification step and cleavage by factor Xa (fXa) to release the recombinant toxin peptide (rPBTx3). After final purification and refolding, rPBTx3 was shown to be identical to the native PBTx3 with respect to HPLC retention time, mass spectrometric analysis and functional properties. The three-dimensional structure of PBTx3 is proposed by homology modelling to contain a double-stranded antiparallel beta sheet and a single alpha-helix, connected by three disulfide bridges. The scaffold of PBTx3 is homologous to most other alpha-KTx scorpion toxins.