Mosquito bites can hit us during UK heatwaves with windows open at night (Image: Getty)
A scientist’s revealed why some get nasty, swollen mosquito bites – yet others barely suffer a scratch. A series of UK heatwaves have seen many of us get in the habit of leaving our bedroom windows open at night to cool down, but in the morning we may wake to find a mosquito bite.
Khalid Beshir, lecturer in biomedical science, at the University of East London, explains that when a mosquito bites you, it injects saliva into your skin. But some of us are hypersensitive to that saliva and our immune system being kept busy can also make us more vulnerable to viruses carried by the insect – such as dengue, Zika and West Nile virus.
Beshir writes in The Conversation: “Our immune system recognises the saliva as foreign and releases histamine – an immune cell chemical that causes allergy symptoms such as redness, swelling and itchiness.
“But crucially a mosquito’s saliva also contains other active compounds that interact with the immune system such as proteins that prevent blood clotting and keep blood flowing so they can feed undisturbed.
“These same salivary proteins influence the immune response that occurs at the bite site. It nudges the immune system toward a ‘Th2’ response. more associated with allergy-type reactions than fighting infection.
“For a simple bite this just means more redness, swelling and itching – but this same immune shift may also make it easier for viruses carried by the mosquito to spread through the body.
“Applying a cold compress soon after a bite may help reduce swelling. Oral antihistamines and mild topical corticosteroid creams can also relieve itching and inflammation, particularly when used early.
“Avoid scratching as this can prolong inflammation, damage the skin and increase the risk of infection. People who develop unusually large reactions, worsening pain or fever should seek medical advice.
“Preventing bites remains the best strategy. Using insect repellents, covering exposed skin and sleeping under insecticide-treated bed nets where mosquito-borne diseases occur can all reduce the risk of being bitten.”
Mosquito Feeding on Human Skin Close Up (Image: Getty)
Why some people react more strongly:
“Children often react more strongly than adults, and reactions tend to be strongest the first few times someone is exposed to a particular mosquito species.
“But the key reason people react so badly to mosquito bites comes down to having a mild hypersensitivity to mosquito saliva.
“A much smaller number of people develop exaggerated local reactions, sometimes called Skeeter syndrome, where swelling extends well beyond the bite itself and is often mistaken for bacterial cellulitis (a skin infection that causes redness and swelling).
“Skeeter syndrome is thought to result from an unusually strong immune response to the proteins in mosquito saliva, involving mosquito-specific antibodies and other inflammatory immune responses.
“Why some people develop this exaggerated response is not fully understood – although age, previous exposure to mosquitoes and individual susceptibility may all play a role.”
Mosquito saliva and disease:
“The implications of mosquito saliva extends beyond the annoying, itchy bites they leave behind.
“Researchers are increasingly recognising that these salivary proteins may influence what happens when pathogens are transmitted from mosquitoes to humans.
“Specifically, the same immune changes that cause the itchy bites in the first place appear to help mosquito-born viruses such as dengue, Zika and West Nile virus establish a stronger initial infection and spread through the body faster than if the virus were injected without saliva alongside it.”
This story originally appeared on Express.co.uk
