A number of complications can develop after you are bitten by an insect.
Secondary bacterial infection
Secondary bacterial infections are a common complication of insect bites. They include:
- impetigo: a highly contagious bacterial infection that causes sores or blisters
- cellulitis: an infection that makes your skin red, swollen and painful
- folliculitis: inflammation (redness and swelling) of one or more hair follicles (the small hole in your skin that an individual hair grows out of)
- lymphangitis: an infection that causes red streaks in your armpit or groin and swollen lymph nodes (small glands that are part of the immune system)
An infection may occur if you scratch an insect bite, or it may be introduced at the time you are bitten.
Infections are usually treated with antibiotics (medication to treat infections that are caused by bacteria), such as flucloxacillin. If you are allergic to penicillin, alternatives include erythromycin or clarithromycin. These will usually be taken orally (by mouth) two or four times a day for seven days.
Lyme disease
Lyme disease is an infection that is caused by the bacterium Borrelia burgdorferi, and is transmitted by a species of tick known as Ixodes ricinus.
Lyme disease is uncommon in the UK, but the Health Protection Agency (HPA) estimates that there are between 1,000 and 2,000 cases of Lyme disease in England and Wales every year. The initial infection is characterised by a red rash that gradually expands outwards from the site of the bite. Antibiotics are usually used to treat the infection.
If untreated, the long-term effects of Lyme disease include problems with the nervous system (brain, spinal cord and nerves) such as:
- meningitis: an infection of the meninges (the protective membranes that surround the brain and spinal cord)
- facial palsy: weakness of the facial muscles that causes drooping of one or both sides of the face
- encephalitis: inflammation (swelling) of the brain (this is rare)
The condition can also damage the joints which can lead to:
- arthritis: pain and inflammation of the joints and bones
- heart problems (occasionally), such as inflammation of the heart muscle (myocarditis) and inflammation of the thin, two-layered, sac-like tissue that surrounds the heart (pericarditis)
See the Health A-Z topic about Lyme disease for more information about this condition.
West Nile virus
West Nile virus is an infection with flu-like symptoms that can be passed on to humans by mosquitoes. Mosquitoes become infected when they feed on infected birds.
There have been no reported cases of the West Nile virus in the UK, but there have been cases elsewhere in the world. Since 2001, the HPA and the Department of Health have been raising awareness of the infection.
See the Health A-Z topic about West Nile virus for more information about this condition.
Malaria
Malaria is a tropical disease that is caused by an infection of the red blood cells (the cells that carry oxygen in the blood). It can be transmitted to humans by the bite of an infected mosquito.
Each year, there are around 1,500 cases of malaria in travellers returning to the UK. A certain type of malaria, known as Plasmodium falciparum, is potentially fatal and accounts for over half of all annual cases in the UK.
See the Health A-Z topic about Malaria for more information about this condition.
