Insect stings and bites: Nursing

Insect stings and bites are relatively common injuries; the difference between them is that stings happen when an insect introduces toxic venom into someone's body, often as a self-defense mechanism; whereas bites happen when an insect pierces someone’s skin in order to feed on their blood.

Let’s start by looking at the anatomy and physiology of the skin. The skin is made of the epidermis, which is an outer layer that acts as a protective barrier against the environment; the dermis, which primarily contains blood vessels and nerve endings; and the hypodermis, which is a layer of connective tissue that provides structural support to the skin.

In addition to being a physical barrier against the external environment, the skin harbors several types of immune cells that participate in the body’s immune response. Normally, the immune system recognizes and acts against pathogens that cause disease, but in some clients, it can overreact and start targeting harmless molecules that don’t cause any problems for most people, including certain foods, medications, as well as the venom or saliva of some insects.

Now, insect stings are caused by stinger insects of the Hymenopteran family, which includes bees, wasps, hornets, yellow jackets, and fire ants; as well as other animals like spiders and scorpions. On the other hand, insect bites are most commonly caused by insects that feed on the host's blood to survive, and these include mosquitoes, chiggers, bedbugs, lice, and ticks.

Since many insects only sting when provoked, risk factors for getting stung include disturbing the animals, such as stepping on a bee-hive, for example. Additionally, insect stings and bites are more likely to happen in clients who spend a lot of time outdoors, especially those who live in warmer climates or near wetlands and forested areas with lots of wood, bushes, and tall grass. Other risk factors include collecting insects as a hobby and not using protective clothes or repellent when spending time outdoors.

Now, while insect stings and bites can result in similar injuries, their pathology is quite different. Stings occur when an insect introduces toxic venom through their stingers into the client’s skin. Here, the problem isn’t really the venom, but rather the immune system’s reaction to it. In mild cases, there may be a local skin reaction around the sting site due to the activation of neighboring immune cells and subsequent release of proinflammatory molecules, like histamine and bradykinin.

With insect bites, on the other hand, the insect pierces the client’s skin during a blood meal. Typically, the insect injects a small amount of anticoagulant saliva that prevents blood from clotting during the blood meal, and that saliva can also activate the immune system’s response. Although most insect bites only cause maddening itches, some can spread vector-borne diseases, including malaria, Lyme disease, and Rocky Mountain Spotted Fever.

In addition, it’s important to be aware that some clients may develop a potentially life-threatening reaction in response to insect stings or bites called anaphylaxis. In anaphylaxis, increased amounts of histamine and other proinflammatory molecules leak into the bloodstream and reach multiple organs, causing generalized swelling, widespread vasodilation, and constriction of the airways. Finally, scratching stings and bites creates more tissue injury, which can serve as an entryway for secondary bacterial infections.

Alright, now the clinical manifestations of insect stings and bites range from mild local skin reactions to potentially life-threatening anaphylaxis. With mild insect stings, clients can present irritation, pruritus, swelling, and redness around the sting site. Severe allergic reactions, on the other hand, can cause intense pain and swelling of a larger part of the body, such as the whole face or limbs.

On the other hand, insect bites generally cause less swelling, but there might be a bump or blister around the bite mark, as well as intense pruritus. Finally, anaphylaxis can cause angioedema, which is when tissues all over the body start swelling up; as well as respiratory symptoms, like shortness of breath, coughing, or wheezing; abdominal cramps, vomiting, or diarrhea; and hypotension.

The diagnosis of insect stings and bites starts with the client’s history and physical assessment. In most cases, no other laboratory or imaging tests are necessary to confirm the diagnosis. However, additional studies, like blood tests, microbiological studies, and an EKG, may be necessary in cases of secondary infection or if a vector-borne disease is suspected.

Now, most insect stings and bites can be treated with simple supportive measures, including cleaning the area with soap and water, applying ice compresses, elevating the area in cases of swelling, and pain management with acetaminophen or NSAIDs. Mild pruritus can be treated with calamine lotion or topical corticosteroids, and for moderate or severe pruritus, a short course of systemic corticosteroids and oral antihistamines, including both H1 and H2 blockers, can be used.