Widow spiders in the New World: a review on Latrodectus Walckenaer, 1805 (Theridiidae) and latrodectism in the Americas

Hypersensitivity vs. uncommonly severe local envenoming by the red-back spider, Latrodectus hasselti Thorell, 1870 (Araneae: Theridiidae)

The genus Latrodectus (Araneae: Theridiidae) consists of 35 widow spider species with global distribution. Envenoming by medically important species, latrodectism, commonly features bite site erythema and diaphoresis, variably severe pain that may be persistent, myalgia/cramping and/or myoclonus, autonomic symptoms, abdominal distress; severe envenoming can be prolonged and include serious effects such as oliguria, hypertension and, rarely, myocarditis/myocardial injury. Red-back spiders (Latrodectus hasselti) are the most common cause of envenoming in Australia and can cause the spectrum of effects noted for other medically important widow spiders. A 34-yr-old woman with a history of previous L. hasselti envenoming and treatment with antivenom was envenomed in her left ankle by a verified L. hasselti (hiding in her boot) while attending an appointment with her primary care physician. She reported some of the common effects of latrodectism including severe, prolonged pain, bite site diaphoresis, and malaise; however, she also developed marked edema that involved the entire left foot. She also exhibited mild hypertension and autonomic/non-specific effects limited to nausea, headache, and anxiety. She was effectively treated with red-back spider antivenom (a total of 4 ampoules) and supportive care; full resolution of the edema required almost 5 days. The uncommon clinical evolution of L. hasselti local envenoming observed in this patient may have been caused by a mixed picture of venom-induced effects and Type I hypersensitivity, but alternatively could be a rare, solely venom-induced manifestation. While provision of patient-centred care for anyone envenomed by Latrodectus spp. requires careful history collection and assessment of comorbidities, differentiation of atopic and direct venom effects may be challenging in some envenomed patients with established complex allergy history.

Venom Hypersensitivity

Stinging insects are a frequent cause of local and systemic hypersensitivity reactions, including anaphylaxis. For those with a history of life-threatening anaphylaxis, venom immunotherapy is effective, safe, and can be life-saving. Arachnids are a much less common source of envenomation through bites or stings and are less likely to cause a hypersensitivity reaction. However, recognizing the clinical manifestations when they do present is important for accurate diagnosis and treatment, and, when indicated, consideration of other diagnoses.

Pulmonary involvement from animal toxins: the cellular mechanisms

Venomous animals and their venom have always been of human interest because, despite species differences, coevolution has made them capable of targeting key physiological components of our bodies. Respiratory failure from lung injury is one of the serious consequences of envenomation, and the underlying mechanisms are rarely discussed. This review aims to demonstrate how toxins affect the pulmonary system through various biological pathways. Herein, we propose the common underlying cellular mechanisms of toxin-induced lung injury: interference with normal cell function and integrity, disruption of normal vascular function, and provocation of excessive inflammation. Viperid snakebites are the leading cause of envenomation-induced lung injury, followed by other terrestrial venomous animals such as scorpions, spiders, and centipedes. Marine species, particularly jellyfish, can also inflict such injury. Common pulmonary manifestations include pulmonary edema, pulmonary hemorrhage, and exudative infiltration. Severe envenomation can result in acute respiratory distress syndrome. Pulmonary involvement suggests severe envenomation, thus recognizing these mechanisms and manifestations can aid physicians in providing appropriate treatment.

Epidemiology of arthropods envenomation in Brazil: a public health issue

Brazil is located between the Equator and Tropic of Capricorn, which allows diverse climates, reliefs, and habitats for arthropods, which sting represents a risk to human health and a public health issue. This manuscript updates the epidemiological data of cases of human envenoming by spiders, scorpions, and insects with medical relevance in Brazil from 2010 to 2021. Epidemiological data were taken using the Brazilian Notifiable Diseases Information System. Statistics of non-parametric data used the Kruskal-Wallis followed by the Nemenyi test. On average, more than 145,000 envenomation and 145 deaths are recorded annually, and more than 60% of deaths are caused by scorpion bites. When the number of deaths was pondered by the number of cases with each arthropod, bees kill the most. Most stings cause mild symptoms and affect men of working age. The incidence decreases during the colder months, which is better noticeable in regions with well-defined seasons. The distribution is distinct among the regions: Southeast, Northeast, and South have the highest rate of bites. The growing number of cases of envenomation reported annually is a serious public health concern, especially involving scorpions, and highlights the importance of studying arthropod venom and improving the therapies.

Assessment of local pain and analgesia in envenoming by wandering spiders (Phoneutria spp.)

Phoneutrism (bites by wandering spiders of the genus Phoneutria) frequently results in local pain. We describe a retrospective cohort study of a case series of phoneutrism admitted to our Emergency Department (ED), in which we used the Numeric Pain Rating Scale (NPRS 0-10) to assess the intensity of local pain upon admission, and recorded the analgesic measures used to control this pain. Other criteria for inclusion were: (1) An age ≥8 years, (2) Treatment exclusively at our ED, and (3) Visualization or photographing the spider at the time of the bite and/or bringing the spider for identification. The patients were classified into three groups based on the intensity of pain at admission: group 1 - mild or no pain (NPRS: 0-3), group 2 - moderate pain (NPRS: 4-6), and group 3 - intense or severe pain (NPRS: 7-10). Fifty-two patients fulfilled the inclusion criteria (n = 11, 14 and 27 in groups 1, 2, and 3, respectively), with a median age of 37 years. The median NPRS upon admission was 7 (interquartile range: 5-8). In patients with an NPRS <7 (groups 1 and 2), only dipyrone was used to alleviate the pain, with six cases in group 1 requiring no analgesia. Most of the cases in group 3 (19/27) were treated with a local anesthetic infiltration (2% lidocaine), in association with analgesics given i.v. in 16 cases (dipyrone, 14; tramadol, 2); additional analgesic treatment was required in seven cases, six of which were treated with tramadol i.v. The median time spent in the ED was 18, 58 and 120 min for groups 1, 2 and 3, respectively. These findings show that most cases of envenoming by Phoneturia spp. involved intense local pain (NPRS ≥7), with local anesthetics being used only in these cases, often in association with dipyrone i.v.

Venom Hypersensitivity

Stinging insects are a frequent cause of local and systemic hypersensitivity reactions, including anaphylaxis. For those with a history of life-threatening anaphylaxis, venom immunotherapy is effective, safe, and can be life-saving. Arachnids are a much less common source of envenomation through bites or stings and are less likely to cause a hypersensitivity reaction. However, recognizing the clinical manifestations when they do present is important for accurate diagnosis and treatment, and, when indicated, consideration of other diagnoses.

Coexistence of Rhabdomyolysis, Myocarditis and Arrhythmia after Spider Bite: A Case Report

BACKGROUND

Rhabdomyolysis after spider bite has been reported in a small number of patients, and myocarditis in even fewer. However, arrhythmia associated with latrodectism in children has not been described in the literature to date.

CASE SUMMARY

A girl presented approximately 4.5 h after being bitten on the left ankle by a black spider. Two unifocal premature ventricular contractions (PVCs) were observed on the electrocardiogram. In laboratory tests, creatine kinase was elevated. On day 2, levels of troponin, pro-brain and natriuretic peptide were elevated. Electrocardiogram revealed inverted and biphasic T waves. Echocardiography revealed mild left ventricular dilation, mitral and aortic valve regurgitation. Holter electrocardiogram showed PVCs. Her laboratory and echocardiography findings completely normalized after discharge, and no arrhythmia was observed on the Holter electrocardiogram during outpatient follow-up.

CONCLUSION

Although spider bites are uncommon, they can cause serious systemic effects. These patients should be evaluated for arrhythmia, rhabdomyolysis and myocarditis.