Arthropod bites and stings

Many species of arthropods (insects, arachnids and others) regularly or occasionally bite or sting human beings. Insect saliva contains anticoagulants and enzymes that cause local irritation and allergic reactions.[1] Insect venoms can be delivered by their stingers, which often are modified ovipositors, or by their mouthparts. Insect, spider and scorpion venom can cause serious injury or death. Dipterans account for the majority of insect bites, while hymenopterans account for the majority of stings. Among arachnids spider bites and mite bites are the most common. Arthropods bite or sting humans for a number of reasons including feeding or defense. Arthropods are major vectors of human disease, with the pathogens typically transmitted by bites and rarely by stings or other contact. Another common negative effect is interference with military activity.[2]

"Biting fly" redirects here. For the South Korean film, see Biting Fly.
Arthropod bites and stings
Other namesBug bite
Tick bite
SymptomsSwelling, itching, pain
ComplicationsAnaphylaxis, envenomation, disease transmission

Signs and symptoms
The left side of the image is showing the temperature increase caused by an insect bite after about 28 hours.
Low-magnification micrograph showing wedge-shaped perivascular inflammation (superficial dermal perivascular lymphoeosinophilic infiltrate), the histomorphologic appearance of an insect bite (H&E stain).

The reaction to a bit or sting is of three types. The typical reaction involves the area around the bite with redness, itchiness and/or pain. A large local reaction occurs when the area of swelling is greater than 5 centimetres (2 in). Systemic reactions are when symptoms occur in areas besides that of the bites, as in the case of anaphylactic shock.[3]

Defensive and predatory bites and stings

Many arthropods bite or sting as a defence against predation, as well as use bites or stings to immobilise and consume prey. Such bites are more likely to be painful. With insect stings a large local reaction may occur (an area of skin redness greater than 10 centimetres (4 in) in size).[4] It can last one to two days.[4] It occurs in about 10% of those bitten.[5]

Feeding bites

Feeding bites have characteristic patterns and symptoms, a function of the feeding habits of the offending pest and the chemistry of its saliva. Feeding bites are less likely to be felt at the time of the bite, but some are.

Pest Preferred body part Felt at time of bite Reaction
mosquitoes exposed appendages usually not Low raised welt, itches for several hours.
midges and no-see-ums exposed appendages usually Itches for several hours.
fleas prefer ankles and bare feet usually May make red itchy welt; several days. Later bites are less severe.
biting flies (Tabanidae) any exposed skin painful and immediate Painful welt, several hours.
bed bugs appendages, neck, exposed skin usually not Low red itchy welts, usually several together resembling rash, slow to develop and can last weeks.
lice pubic area or scalp usually not Infested area intensely itchy, with red welts at bite sites.
larval ticks Anywhere on body, but prefer covered skin, crevices. Usually not; may be scratched off before they are seen. Intensely itchy red welts lasting over a week.
adult ticks covered skin, crevices, entire body usually not Itchy welt, several days. May transmit diseases.
mites mainly on the trunk and extremities usually not Intensely itchy welts and papules that may last for days.

Microscopic appearance

The histomorphologic appearance of insect bites is usually characterized by a wedge-shaped superficial dermal perivascular infiltrate consisting of abundant lymphocytes and scattered eosinophils. This appearance is non-specific, i.e. it may be seen in a number of conditions including:[6]

As vectors of disease
Main article: Disease vector

In addition to stings and bites causing discomfort in of themselves, bites can also spread secondary infections if the arthropod is carrying a virus, bacteria, or parasite. Malaria is one of many diseases primarily spread via mosquito bites.

Biting and stinging arthropods
Aedes aegypti, the yellow fever mosquito, biting. Female mosquitoes feed on blood. This species is known for also transmitting yellow fever.

A bite is defined as coming from the mouthparts of the arthropod. The bite consists of both the bite wound and the saliva. The saliva of the arthropod may contain anticoagulants, as in insects and arachnids which feed from blood. Feeding bites may also contain anaesthetic, to prevent the bite from being felt. Feeding bites may also contain digestive enzymes, as in spiders; spider bites have primarily evolved to paralyse and then digest prey. A sting comes from the abdomen; in most insects (which are all largely hymenopterans), the stinger is a modified ovipositor,[7] which protrudes from the abdomen. The sting consists of an insertion wound, and venom. The venom is evolved to cause pain to a predator, paralyse a prey item, or both. Because insect stingers evolved from ovipositors, in most hymenopterans only the female can sting. However, there are a few orders of wasp where the male has evolved a "pseudo sting" - the male genitalia has evolved two sharp protrusions which can deliver an insertion wound. However, they do not contain venom, so they are not considered a true sting.[8] In ants that bite instead of sting, such as the Formicinae, the bite causes the wound, but during the bite the abdomen bends forward to spray formic acid into the wound, causing additional pain. In arachnids that sting (all largely scorpians), the stinger is not a modified ovipositor, but instead a metasoma that bears a telson.[9] (Scorpians lack an ovipositor entirely and give birth to live young.)

Insects
Further information: Insect bites and stings
The botfly lays its eggs in the wound after biting, causing an infection of parasitic maggots called Myiasis.

Diptera (True flies)
Venom droplet from a wasp stinger. Wasp stings in humans can provoke a strong localised reaction, and rarely, anaphylaxis in those with a wasp sting allergy.

Hymenoptera
Flea bites. Rarely, some species of fleas can also transmit secondary infections, such as flea-borne (murine) typhus.

Siphonaptera (Fleas)
Louse bites. Lice do not carry disease.

Phthiraptera (Lice)

Other insects
White-tailed Spider bite

Spiders
Main article: Spider bite

Mites
Further information: Acariasis

Scorpions
Further information: Scorpion toxin
  • All species sting

Myriapoda

References
  1. Atkins MD (1978). Insects in Perspective. Prentice Hall. p. 359. ISBN 978-0-02-304500-4.
  2. Mehr ZA, Rutledge LC, Echano NM, Gupta RK (December 1997). "U.S. Army soldiers' perceptions of arthropod pests and their effects on military missions". Military Medicine. 162 (12): 804–807. doi:10.1093/milmed/162.12.804. PMID 9433086.
  3. Goddard J (2002). Physician's guide to arthropods of medical importance. Boca Raton: CRC Press. pp. 14. ISBN 978-0-8493-1387-5.
  4. Ludman SW, Boyle RJ (2015). "Stinging insect allergy: current perspectives on venom immunotherapy". Journal of Asthma and Allergy. 8: 75–86. doi:10.2147/JAA.S62288. PMC 4517515. PMID 26229493.
  5. Maynard RJ, Jones AL, Marrs RC, Maynard RL (2003). Antidotes. London: Taylor & Francis. p. 118. ISBN 978-0-203-48507-1. Retrieved 7 June 2016.
  6. Alsaad KO, Ghazarian D (December 2005). "My approach to superficial inflammatory dermatoses". Journal of Clinical Pathology. 58 (12): 1233–1241. doi:10.1136/jcp.2005.027151. PMC 1770784. PMID 16311340.
  7. Gwaltney-Brant SM, Dunayer E, Youssef H (2018). "Terrestrial Zootoxins". In Gupta RC (ed.). Veterinary Toxicology. Elsevier. pp. 781–801. doi:10.1016/b978-0-12-811410-0.00058-1. ISBN 978-0-12-811410-0.
  8. Sugiura S, Tsujii M (December 2022). "Male wasp genitalia as an anti-predator defense". Current Biology. 32 (24): R1336–R1337. doi:10.1016/j.cub.2022.11.030. PMID 36538881. S2CID 254874084.
  9. van der Meijden A, Kleinteich T (April 2017). "A biomechanical view on stinger diversity in scorpions". Journal of Anatomy. 230 (4): 497–509. doi:10.1111/joa.12582. PMC 5345679. PMID 28028798.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.