Bites and stings

Published on 19/03/2015 by admin

Filed under Dermatology

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Bites and stings

Dirk M. Elston

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

image

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.

Specific investigations

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

First-line therapy

Prevention  
image DEET A
image Permethrin A
image Picaridin B
image Combinations of DEET and permethrin A
Flea treatments for pets  
image Lufenuron A
image Fipronil A
image Imidacloprid A
Anaphylaxis  
image Epinephrine A
image Immunotherapy A
Spider bites  
image Rest, ice, and elevation B
image Tetracycline or triamcinolone for brown recluse bites C
image Antivenin for brown recluse bites C
image Antivenin for black widow and red-black spider bites A
Scorpion stings  
image Antivenin for stings in Arizona B
image Prazosin for Indian red scorpion stings A
Arthropod-borne infections  
image Lyme borreliosis  
 – Tetracycline A
 – Amoxicillin in children A
 – Intravenous cephtriaxone A
image Rocky Mountain spotted fever  
 – Doxycycline A
image Human monocytic ehrlichiosis  
 – Doxycycline A
image Human anaplasmosis  
 – Doxycycline A
image Babesiosis  
 – Azithromycin and atovaquone A
 – Quinine and clindamycin A

image

Second-line therapies

Repellents  
image Botanicals B–C
image Novel pyrethroids B–C
Relief of pruritus  
image Camphor and menthol E
image Pramoxine E
image Lidocaine E
image Benzocaine E
image Lidocaine/prilocaine E
Teatment of bite reactions
image Superpotent and potent topical corticosteroids E
image For young children: mild to moderate strength topical corticosteroids E
image Local ice C
image Local heat C
Indian red scorpion stings
image Captopril C
image Antivenin D
Arthropod-borne infections
Babesiosis  
image Atovaquone–proguanil in immunosuppressed patients C

image

The use of concentrated heat after insect bites/stings as an alternative to reduce swelling, pain, and pruritus: an open cohort-study at German beaches and bathing-lakes.

Müller C, Großjohann B, Fischer L. Clin Cosmet Investig Dermatol 2011; 4: 191–6.

A medical device of class 2A (non-invasive device) to reduce swelling, pruritus, and pain after insect bites/stings via direct heat was evaluated in a prospective, single-arm cohort study using a visual analog scale to denote the intensity of symptoms. Of the 146 subjects, 93 (63.7%) were stung by wasps, 33 (22.6%) were bitten by mosquitoes, and eight suffered bee stings (5.3%). Pain reduction was the dominant effect. Concentrated heat may be an alternative to ice and other standard measures for symptomatic relief of swelling, pain, and pruritus. Objective data are needed to demonstrate comparative effectiveness, as ice remains very inexpensive by comparison.

Field evaluation of commercial repellents against the floodwater mosquito Psorophora columbiae (Diptera: Culicidae) in St. Johns County, Florida.

Qualls WA, Xue RD, Holt JA, Smith ML, Moeller JJ. J Med Entomol 2011; 48: 1247–9.

Three plant-based repellents were evaluated against OFF! (N,N-diethyl-m-toluamide/N,N-diethyl-3-methyl-benzamide, also called DEET). The first alternative had the active ingredient 30% oil of eucalyptus. The second contained 3% soybean oil, 6% geranium oil, and 8% castor oil, and the third contained 7.75% 2-undecanone. The three were tested against the floodwater mosquito Psorophora columbiae. The eucalyptus oil product provided the longest protection time (330 minutes).

This study provides further evidence that botanicals can be effective as repellents. Contact allergy may be a problem with these agents.

Third-line therapies

Treatment of bites
image Intralesional corticosteroids E
Repellents
image Newer botanicals C–E

image

Repellent plants provide affordable natural screening to prevent mosquito house entry in tropical rural settings: results from a pilot efficacy study.

Mng’ong’o FC, Sambali JJ, Sabas E, Rubanga J, Magoma J, Ntamatungiro AJ, et al. PLoS One 2011; 6: e25927.

In addition to the use of essential oils, strategies for reducing mosquito house entry can be based on planting the tall and densely foliated repellent plant Lantana camara L. as a natural screen. This pilot efficacy study showed 83% fewer Anopheles funestus s.s. (IRR 0.17, 95% CI 0.09-0.32, p<0.0001), 56% fewer Anopheles gambiae s.s. (IRR 0.44, 95% CI 0.28-0.68, p<0.0001), and 50% fewer mosquitoes of any kind (IRR 0.50, 95% CI 0.38-0.67, p<0.0001) in the houses with Lantana screens.

The cost of this intervention is low ($1.50 per house), suggesting it may play a role, especially in areas with limited resources.

An ethnobotanical survey of mosquito repellent plants in uMkhanyakude district, KwaZulu-Natal province, South Africa.

Mavundza EJ, Maharaj R, Finnie JF, Kabera G, Van Staden J. J Ethnopharmacol 2011; 137: 1516–20.

Plants traditionally used to repel mosquitoes in South Africa were studied with the aim to identify effective plant species as well as the condition of the plant material used and the method of application. The most frequently recorded species was Lippia javanica (91.67%), followed by Aloe ferox (11.67%), Sclerocarya birrea (5%), Melia azedarach (3%), Balanite maughamii (3%) and Mangifera indica (3%). Typically, it was the leaves that were used, and in a dry state. Burning of dried plant materials was the most common method of application.

In addition to the data noted above, nine plant species were documented for the first time as mosquito repellents.

Repellent activity of plant essential oils against bites of Lutzomyia migonei (Diptera: Psychodidae).

Nieves E, Fernández Méndez J, Lias J, Rondón M, Briceño B. Rev Biol Trop 2010; 58: 1549–60.

The authors evaluated the repellent effect of essential oils extracted from eight plants species against bites of Lutzomyia migonei, a Leishmania vector. The plants included Hyptis suaveolens, Pimenta racemosa, Piper marginatum, Monticalia imbricatifolia, Pseudognaphalium caeruleocanum, Espeletia shultzii, Plecthranthus amboinicus and Cinnamomun zeylanicum. Repellency tests were performed under laboratory conditions using cage assays. The oils of P. caeruleocanum and C. zeylanicum were the most effective. P. amboinicus oil showed an irritant effect and the oils of P. marginatum, H. suaveolens and P. racemosa showed no repellent effect.

In this study, P. caeruleocanum and C. zeylanicum oils provided 95% protection against bites of L. migonei for 3 hours. The results must be validated by field trials.

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