Bites and stings

Published on 19/03/2015 by admin

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Last modified 19/03/2015

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Bites and stings

Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports

This chapter presents strategies for the prevention and management of bites and stings.

Management strategy

Bite reactions

DEET is effective against a broad range of arthropods. Picaridin is effective against mosquitoes. Permethrin can be used on fabric. A veterinarian should be consulted about flea infestation in pets. Antivenin is available for many arachnid toxins, but most respond to rest, ice, and elevation.

If prevention fails, second line treatments aim to improve pruritus. Topical antipruritics, such as 1/4% camphor and menthol, and topical anesthetics, such as pramoxine and lidocaine, can be helpful. For persistent bite reactions, topical or intralesional corticosteroids may be helpful.

Anaphylaxis

Individuals who experience anaphylaxis in response to stings should be referred to an allergist for desensitization. Rush desensitization is possible for those with life-threatening allergy. Patients with a history of anaphylaxis should also carry an epinephrine autoinjector (EpiPen®).

Vector-borne disease

Most tick-borne illness responds to doxycycline. For early Lyme disease, evidence suggests that a 10-day course is as effective as longer courses of antibiotic. Babesiosis responds to clindamycin and quinine, but azithromycin and atovaquone may be as effective with a lower incidence of side effects. Atovaquone–proguanil has been effective in refractory cases in immunocompromised patients.

Specific investigations

Complete blood count and fibrin split products after brown recluse spider bite

Rickettsial immunofluorescence and immunoperoxidase

Lyme serologic tests

ELISA, PCR, and immunofluorescence for viruses such as West Nile, dengue, and chikungunya

PCR assays can also be used to identify biting insects too small for conventional identification. Tryptase levels can be used in forensic investigations to confirm death from anaphylaxis

Allergy blood testing: a practical guide for clinicians.

Siles RI, Hsieh FH. Cleve Clin J Med 2011; 78: 585–92.

Blood tests are available that measure levels of specific immunoglobulin E (IgE) against venoms.

These tests can confirm the diagnosis of sensitivity to a given arthropod.

Causes of ant sting anaphylaxis in Australia: the Australian Ant Venom Allergy Study.

Brown SG, van Eeden P, Wiese MD, Mullins RJ, Solley GO, Puy R, et al. Med J Aust 2011; 195: 69–73.

Serum IgE testing against ant venom panels was used to determine the Australian native ant species associated with ant sting anaphylaxis.

Diagnostic venom-specific IgE testing is now feasible and being used for epidemiologic studies. Serum IgE testing enhances the accuracy of diagnosis and has become standard prior to administering species-specific venom immunotherapy.

Detection of West Nile virus genome and specific antibodies in Iranian encephalitis patients.

Chinikar S, Javadi A, Ataei B, Shakeri H, Moradi M, Mostafavi E, et al. Epidemiol Infect 2012; 140: 1525–9.

The authors studied a total of 632 patients with fever and loss of consciousness by CSF analyses by reverse transcriptase-PCR (RT-PCR) and serum IgG antibodies, confirming a low incidence of West Nile virus infection in the population studied.

A history of insect bite, blood transfusion and transplantation are risk factors for being positive by RT-PCR and serum IgG. The two assays are complementary.

Molecular characterization of Swiss Ceratopogonidae (Diptera) and evaluation of real-time PCR assays for the identification of Culicoides biting midges.

Wenk CE, Kaufmann C, Schaffner F, Mathis A. Vet Parasitol 2012; 184: 258–66.

Biting midges of the genus Culicoides cause insect bite hypersensitivity and may act as disease vectors. As they are very small, morphological identification of these tiny insects may be difficult. Real-time PCRs detecting portions of the mitochondrial cytochrome oxidase 1 gene showed some success in identifying specific species.

The assays require improvement, but are promising for identification of small species of insects.

Usefulness of post mortem determination of serum tryptase, histamine and diamine oxidase in the diagnosis of fatal anaphylaxis.

Mayer DE, Krauskopf A, Hemmer W, Moritz K, Jarisch R, Reiter C. Forensic Sci Int 2011; 212: 96–101.

Significantly higher histamine levels were present in blood samples taken more than 24 hours post mortem, and the timing of blood collection had no effect on tryptase levels.

Elevated tryptase levels above 45 µg/L may support the diagnosis of fatal anaphylaxis.

First-line therapy

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Prevention
DEET	A
Permethrin	A
Picaridin	B
Combinations of DEET and permethrin	A
Flea treatments for pets
Lufenuron	A
Fipronil	A
Imidacloprid	A
Anaphylaxis
Epinephrine	A
Immunotherapy	A
Spider bites
Rest, ice, and elevation	B
Tetracycline or triamcinolone for brown recluse bites	C
Antivenin for brown recluse bites	C
Antivenin for black widow and red-black spider bites	A
Scorpion stings
Antivenin for stings in Arizona	B
Prazosin for Indian red scorpion stings	A
Arthropod-borne infections
Lyme borreliosis
– Tetracycline	A
– Amoxicillin in children	A

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