I. AS PARASITES

Arthropods are of significance because they can be both parasites themselves and can transmit pathologic organisms. As parasites, they can produce harm in the following ways:

They produce pathologic condition(s) (direct harm) to the host by causing:

Dermatitis (above). Skin irritation resulting from bites of arthropods. Damage may be local or extensive. Examples include mosquito bites and mite infestations.

Envenomization. Some arthropods inject toxic substances (venom) when they bite. Venoms are introduced into the host by 1) bites (spiders)(above, left), 2) stings (wasps) 3) urticating hairs (caterpillars)(above, right), 4) contact (blister beetles).

Effects of venom are classified as:

• Hemolytic
• Hemorrhagic
• Neuro-toxic
• Vesiccating

• Allergy. Allergic reactions resulting from exposure to arthropods. The allergens may be present as part of the organism itself or a part of a secretion produced by the parasite. Examples include flea bite allergy.
• Myiasis. The invasion of tissue by larval Diptera. Examples include bot flies and warbles.
• Accidental injury. Injury due to accidental contact with arthropods and their secretions.
• Entomophobia. The fear of arthropods regardless if harmful or not. There are more examples in human medicine than in veterinary medicine.

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