What Should I Know About Bites of Insects and Arachnids

Home , Arachnid, Insect bites and stings

EUROPEAN ACADEMY OF DERMATOLOGY AND VENEREOLOGY Information Leaflet for Patients

WHAT SHOULD I KNOW ABOUT BITES OF INSECTS AND ARACHNIDS

The aim of this leaflet This leaflet is designed to help you understand more about bites and stings from insects and arachnids (spiders, ticks, mites, and scorpions). It will tell you about these kinds of animals, what is dangerous about the venom, what can be done for the main complications, and how to avoid the bites in the first place. For further information, you will also find in a second leaflet a selection of the most important venomous species and in what cases you need to seek emergency help. WHAT SHOULD How are insects distinguished from arachnids? While they are both invertebrate animals, the zoological characteristics are different I KNOW ABOUT between insects and arachnids. Insects have 3 pairs of legs and are possibly armed with stingers, venomous glands, and/or fangs (examples: mosquitos, flies, bees, wasps, ants, BITES OF beetles, fleas, ticks, and caterpillars). Arachnids have 4 pairs of legs, and their venomous glands in the mouth region carry the fangs for eating or defence (examples: spiders, mites, INSECTS AND ticks, and scorpions). Some spiders do not bite; they spray the venom towards the prey or ARACHNIDS aggressor.

How are bites and stings different What is dangerous about bites between insects and arachnids? and stings from insects and arachnids? • Insect bites and stings: Clinical characteristics • Insect bites and stings: Risks and Most insect stings involve a single puncture consequences wound with a papule (bump) formation, a Insect bites and stings in human beings localised urticaria (known as hives, with worldwide are very common and sometimes swelling and redness) and itch. These nearly unavoidable. They often need symptoms usually subside within a few medical treatment, either due to bacterial hours or days. Bites from insects are done infection of inflamed bite reactions, a toxic mainly to stabilise the insect’s body before reaction, or allergies against components stinging. So, insect bites cause fewer of the insect’s venom. Allergies can be life- symptoms than insect stings, and subside threatening. Several insect species that are much more quickly. Venom-spraying dangerous for people are listed below. insects, like some ant species (e.g. “fire ants”), leave a localised redness or eczema • Spider bites: Risks and and sometimes blistering. Extremely rarely, consequences insect bites cause wound healing disorders. Spider bites in human beings are extremely rare and mostly avoidable. Spiders only bite • Spider bites: Clinical characteristics people in self-defence, usually as a result The typical feature of spider bites is the of unexpected human behaviour. Also, the twin-puncture wound of the spider’s fangs of most spiders worldwide are much fangs. Most spider bites are associated too small to penetrate human skin and do with fewer symptoms than an ordinary harm, and the spider’s venom is usually mosquito bite, and even the small puncture too mild to cause serious problems. A wounds of both fangs are sometimes hardly limited number of spiders, mostly residents visible. Some spitting spiders (even those of tropical or subtropical regions, pose a who bite like the “brown recluse spider”) problem to human beings. The reaction may leave a severe necrotic wound (dead is always toxic/venomous. There are no tissue) or an ulcer with a black crusty allergies known to exist against spiders. A eschar or scab. “Black widows” and some selection of a few, rather toxic/venomous “bird spiders” may additionally cause severe species are listed below. Only bites of these neurological symptoms, such as extremely spider species require medical treatment. painful muscle cramps, anxiety, headache, increased salivation, increased sweating, numbness, restlessness, seizures, and more.

EADV INFORMATION LEAFLET FOR PATIENTS I TROPICAL DERMATOLOGY What are the clinical signs of A systemic reaction is always a case of bites and stings from insects and severe emergency. Immediate help of an arachnids? emergency physician and intensive care in a hospital is necessary. • Local reaction Reactions to bites and stings from What about people with an insects or arachnids are usually caused impaired immune system? by toxic components of the venom. The People with very dry and tender skin or most common reaction is mild local genetic skin disorders (e.g. ichthyosis inflammation, showing little well-defined vulgaris), skin immune deficiency (e.g. atopic swelling, redness, heat, moderate itch, dermatitis), autoimmune diseases leading to or pain around the affected area, which reduced skin defence mechanisms, immune subsides after a short while. As long as suppressive medical treatment, infectious the inflammation stays local, this is, per diseases impairing the immune system, definition, never an allergy. Local reactions or any form of malignant diseases may need to be monitored, but usually respond react more severely to any insect stings or to local treatment. arachnid bites. Sometimes, a sting or bite is complicated People with a predisposition to having by pulsating local pain and swollen regional allergies may develop an allergy against lymph nodes. These may be signs of a stinging insects (like wasps or bees). Stings secondary bacterial infection and include: may then cause a life-threatening situation. pustules and secretion of pus, lymphangitis In these cases, emergency treatment is (infection of lymph vessels), or fever. In this required. The dermatologist/allergologist case, contact your dermatologist; this often can provide medical help, and assistance needs antibiotic treatment. with the diagnosis of specific allergies and • Regional reaction preventive measures.

A local reaction that grows and affects How are bites and stings from a whole region (e.g. arm or leg) means a regional reaction. As long as the area insects and arachnids treated? around the sting is involved and no other What you can do: part of the body, the reaction per definition is exaggerated but not systemic or allergic. • Cooling devices You need to see your dermatologist for Local reactions mainly just need cooling regional reactions. with cold water, ice packs, or gels.

• Systemic reaction • Over-the-counter medicine If you get stung or bitten somewhere (e.g. In other cases, topical steroid creams are in the right foot), and you develop reactions often helpful (available over-the counter in at distant body parts (e.g. the hands, parts some countries). Also, antihistamine tablets of the face, or elsewhere) or if you have or drops (obtainable without prescription) a generalised urticarial rash affecting the may help to decrease the itch and swelling. whole body, this suggests a severe systemic allergic reaction, called anaphylaxis. • Electrical devices for local thermotherapy (heat therapy) More severe or even life-threatening symptoms may occur, such as breathing So-called mosquito bite relievers work problems, tachycardia (palpitations), on the principle that most insect venom abdominal pain, increased bowel movements is thermolabile (sensitive to heat). These with faecal urgency or incontinence, nausea, reusable pocket-sized devices work with vomiting, diarrhoea, cardiovascular collapse electrical heat and claim to deliver heat at or “shock,” unconsciousness, cardiac arrest, the right temperature in order to deactivate and death. venom from thousands of different species

EADV INFORMATION LEAFLET FOR PATIENTS I TROPICAL DERMATOLOGY of insects and sea creatures in about 30 that transmits sleeping sickness in Sub- WHAT SHOULD seconds. Saharan Africa, is especially attracted by I KNOW ABOUT blue colours. So, in these areas wear light When should I see a clinician? colours, which can even keep you cooler BITES OF in the sunny heat. Be sure that you cover • Growing inflammation as much of your skin as possible and wear INSECTS AND If the inflammation grows and initial signs of clothes made of tightly-woven fabric so that allergic reaction or bacterial infection occur, mosquitoes cannot penetrate. Wear loose- ARACHNIDS the help of your dermatologist is needed. fitting clothing, because if the material is Your dermatologist will decide whether not close to your skin, insects cannot bite to prescribe stronger topical treatment or through to you. Make sure that the cuffs systemic prescriptions. and collar are tight enough to prevent insects from getting through. In all cases of stronger reactions, even out- of-office hours of your local dermatologist, • Fragrance do not hesitate to contact the emergency Avoid fragrance of all kinds, as it may attract department of your local hospital or call an insects. ambulance. • Repellents • Bacterial infections Regarding the use of repellents to deter Bacterial infections may need antibiotic insects, there are many different products prescriptions. In advanced stages, you may on the market, some effective and some need to have antibiotic intravenous (i.v.) useless. Pyrethroids are synthetic organic infusions as an in-patient at a hospital. compounds similar to the natural pyrethrins from chrysanthemums. Pyrethroids now • Allergies constitute the majority of commercial Severe forms of allergies will be treated household insecticides. In general, they by your dermatologist with cortisone are harmless to human beings in lower and antihistamines (as tablets, injections, doses. DEET is effective for ticks and insect or infusions). After every allergy caused bites. It is most helpful against malaria- by venomous insect bites, contact your carrying mosquitoes and horseflies, and dermatologist to discuss the possibilities of reasonably effective against large horseflies, a hyposensitization therapy. This is the only gnats, and midges. For further information way to treat the cause of an allergy. and recommendations, ask your local dermatologist. Your dermatologist will also prescribe you an Allergy Emergency Kit (antihistamine • Fly screens and bed nets drops, liquid cortisone, and an epinephrine For indoor protection, use enclosed fly syringe). This is obligatory and must be screens at windows and doors as well as carried with you all the time. It is important mosquito nets (especially, to protect the to pay attention to the expiration dates sleeping area). Some venomous insects are of the medications (please note that the very small, therefore an adequately small prescribed medications presented here may mesh size is important. vary from country to country). • General precautions How can I avoid bites and stings In general, the best thing to do is to avoid from insects and arachnoids? places which are preferred by swarms of venomous stinging insects, especially at • Clothing times when they are known to be most Insects are often attracted by dark- active. Additionally, never try to catch, hold, coloured clothing. The Tsetse fly, an insect or squeeze insects and arachnids. n

While every effort has been made to ensure that the information given in this leaflet is accurate, not every treatment will be suitable or effective for every person. Your own clinician will be able to advise in greater detail.

PRODUCED BY THE EADV TROPICAL DERMATOLOGY TASK FORCE