By Dr Ananya Mandal, MD
Insect bites or stings may lead to mild irritation, itching, redness and swelling and may often go away within a few hours. In some cases however there may be complications after being bitten or stung by the insect. 1-5
Common complications include allergic reactions, secondary infections and so forth.
Allergic reactions to insect bites
Allergic reactions like rashes, hives, nettle rash, facila swelling (angioedema) may be seen.
Severe allergic reactions or anaphylactic shock may be potentially life threatening. Symptoms include breathing problems, rapid fall in blood pressure, shock, swelling and constriction of the air passages, swelling of the face, lips and neck etc.
Insect bites or stings may often be itchy and repeated scratching may lead to skin abrasions and predispose to skin infections. Some of the skin infections may manifest as sores and blisters that are often filled with pus. This is called impetigo.
An inflammation and pus point may often affect hair follicles of the skin and lead to folliculitis. When large areas of skin and underlying tissues are affected, it is called cellulitis.
If the infection spreads to the lymph nodes of the armpits, groin or neck, it is termed lymhangitis.
While folliculitis and impetigo may be treated with locally applied antibiotic creams and ointments, more generalized infections like cellulitis or lymphangitis may require oral antibiotic pills.
This is borne by a species of tick known as Ixodes ricinus. There are around a thousand new cases of this disease in England and Wales every year. There may be a red rash at the site of the bite that spreads gradually.
Antibiotics are usually used to treat the infection. If left untreated Lyme disease may affect the central nervous system and lead to complications like facial weakness or paralysis, meningitis or encephalitis.
Lyme disease over long term may also lead to joint problems like arthritis and heart muscle problems like myocarditis. The tissue layer that cover the heart called the pericardium may also be inflamed (pericarditis) with Lyme disease.
West Nile virus infection
This virus is carried by mosquitoes. Usually there are influenza like symptoms of fever, headache, body aches, nausea, vomiting, and sometimes swollen lymph nodes or a skin rash. Complications include encephalitis and meningitis and may manifest with seizures.
Malaria is a parasitic infection that is carried by mosquitoes. It is common in hot and humid climates. Travellers to tropical countries often bring back the infection to more developed and cooler countries.
Malaria is manifested with fever, chills and rigor and may lead to severe complications and even death without treatment. There are two main types of malaria infection with Plasmodium vivax and Plasmodium falciparum. Infection with P. Falciparum is potentially life threatening if not detected and treated early.
Rocky Mountain Spotted Fever
Rocky Mountain Spotted Fever is caused by bacterium Rickettsia rickettsii that is transmitted by infected ixodid (hard) ticks. There are three main symptoms of fever, rash, and history of tick bite.
There may be nausea, vomiting, severe headache, and loss of appetite, pain in the abdomen, muscle aches and diarrhoea. After initial 2 to 5 days there may be a red rash on the wrists, forearms, palms, soles and ankles.
Other insect borne diseases
Other insect borne diseases include:
- relapsing fever and Chagas disease transmitted by bed bugs in Mexico
- Yellow fever transmitted by mosquitoes
- Dengue fevertransmitted by mosquitoes
- onchocerciasis by black flies
- trypanosomiasis by tsetse flies or by reduvid bugs
- leishmaniasis transmitted by sandflies
- loiasis by Deer flies or Mango flies
- Ross River fever by mosquitoes
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)
Last Updated: Jun 15, 2013