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Skin cream used to treat GENITAL WARTS could protect people against diseases carried by mosquitoes

A skin cream used to treat genital warts may protect people against deadly diseases carried by mosquitoes, such as Zika.

Researchers found applying Imiquimod or Aldara on bites within an hour of infection stopped it from spreading in lab trials on human skin.

The cream boosts the immune system to send more white blood cells to the site of infection, killing the virus immediately.

The cream, also used for some types of skin cancer, worked against four mosquito-borne viruses – Zika, chikungunya, Semliki Forest and Bunyamwera. 

Scientists at the University of Leeds hope the method will work against other lethal diseases, such as dengue and the West Nile virus. 

A skin cream used to treat genital warts and skin cancer could protect people against deadly diseases carried by mosquitoes, researchers have suggested (file photo)

Dr Steven Bryden, who co-authored the study, said the cream boosted the immune system rather than targeting a specific virus.

It therefore had the potential to be a ‘silver bullet’ for a ‘wide range’ of diseases carried by mosquitoes, he said.

One of those is Zika, first identified in humans in Uganda in 1952. It’s named after the Ziika Forest of Uganda, where the virus was first isolated in 1947 in monkeys.


The Zika virus is spread by mosquito bites, between people during unprotected sex, and from pregnant mothers to their children.

It cannot be cured or prevented with medicines. Although most adults do not become seriously ill from the infection, it can cause serious birth defects if pregnant women get it.

Foetuses’ brains can be affected by the virus when it is passed on from the mother and it can cause microcephaly.

Microcephaly is a condition in which babies’ heads are unusually small, which can lead to seizures, delayed development and other disabilities.

The virus can also increase the risk of unborn children developing Guillain-Barre syndrome – an uncommon illness in which the immune system attacks the nerves and can cause muscle weakness and paralysis.

Zika is a tropical disease and is most common in Central and South America, Africa and South East Asia.

There was an outbreak of the virus in Brazil’s capital, Rio de Janeiro, in 2016 and there were fears that year’s Olympic Games would have to be cancelled after more than 200 academics wrote to the World Health Organization warning about it.

The virus is not commonly found in developed countries like the UK, US and Australia. But it is present in the Pacific Islands such as Fiji and Tonga, where the pregnant Duchess of Sussex will visit on her royal tour this month.

Source: Centers for Disease Control and Prevention

It cannot be cured or prevented with medicines. Although most adults do not become seriously ill from the infection, it can cause serious birth defects if pregnant women get it.

An outbreak in 2015 spread throughout Latin America and the Caribbean and was blamed for a 24-fold increase in the number of babies born with abnormally small heads, known as microcephaly, which lead many of them to die. 

Another mosquito-borne virus, chikungungya, causes fever, joint pain, headaches and a rash. There are thought to have been around two million cases worldwide, with around 2,000 deaths. Outbreaks have occurred in countries in Africa, Asia and parts of Europe, as well as those in the Indian and Pacific Oceans.

And while less threatening, the Semliki Forest and Bunyamwera viruses both cause symptoms including headaches and fever. Semliki Forest virus is found throughout Africa and parts of Asia, while Bunyamwera is present throughout much of sub-Saharan Africa.

Dr Bryden and his colleagues took small skin samples from 16 people and kept them healthy in a lab.

They cut each sample in half and allowed both to be infected with Zika by a mosquito. 

After an hour they applied the cream to one half of each sample and left the other half without treatment.

Two days later they found that the skin which had not been treated with the cream had more than 70 times the level of viral infection than that which had been treated.

For chikungunya, the skin which did not have any cream had more than 600 times the amount of the virus.

In both cases, the cream halted the infections from spreading. The researchers believe it would not have infected the whole body had it occurred in a person.

The team tested this with mice infected with Semliki Forest, chikungunya and Bunyamwera viruses. 

The mice were bitten by mosquitoes carrying Semliki Forest and half were treated with the cream and half were not. 

Two weeks later, all of the mice with Semliki Forest which had not been treated with the cream were dead. But 65 per cent of those which were given the cream survived.

Chikungunya causes arthritis in both humans and mice, so scientists could measure the extent of infection by looking at the infected mice’s ankle joints.

Two weeks after being infected, 70 per cent of those which did not have cream had the virus in their ankles, compared to 30 per cent for those which did.

In those which were treated, their joints had 90-times less virus, which suggested the cream had prevented a more severe infection.

Lastly, researchers looked at the Bunyamwera virus which is genetically distant from other viruses carried by mosquitoes. 

They did this to see if the cream could work against diseases unlike those already tested. 

After infection, mice which were not treated with cream had up to 10,000 infectious particles in their bloodstream, compared to less than 100 for those which had been treated.

The research team said further tests were needed before the cream could safely be recommended for use on mosquito bites.

Co-author Dr Kave Shams said: ‘We are hopeful that one day this discovery could help a vast number of people to avoid disease, particularly in parts of the world hardest hit by these devastating diseases.

‘If we can repurpose this cream into an anti-viral treatment option, it could be a useful addition to mosquito repellent as a way of avoiding infection from harmful diseases.

‘This approach could be particularly valuable for people at high risk of infection, such as those with a suppressed immune system, and in times of disease outbreak.’

Dr Bryden added: ‘By boosting the immune system and not targeting a specific virus, this strategy has the potential to be a ‘silver bullet’ for a wide range of distinct mosquito-borne viral diseases.’

The team are now hoping to see if the cream can reduce infections in human populations.

The research was published in the journal Science Translational Medicine.


Around 20 per cent of people are more prone to mosquito bites.

And while scientists are yet to find a cure, they do have some ideas as to why the insects attack some of us more than others.  

Blood type

Certain blood types are more attractive to taste buds of mosquitoes. 

Research has shown that people who have Type O blood – the most common blood type – tend to get bitten twice as much as those with Type A. People with Type B blood get bitten somewhere in the middle. 

Exercise and metabolism

Working up a sweat during exercise can also make a person more susceptible to a mosquitoes bite.

Strenuous exercise causes higher body temperatures and a buildup of lactic acid, which emit yummy signals to the insects.     


A cold glass of beer makes you sweat and your body release ethanol, which may be why mosquitoes like to land on beer drinkers. 

Skin bacteria 

Levels of bacteria on the human skin can entice mosquitoes to bite, particularly where bacteria clusters like on the ankles and feet. 

Having different types of bacteria on the skin, however, tends to turn the insects off. 

Body odour 

Mosquitoes use even the faintest of human body odours when searching for potential victims.

It’s been known for some time that female mosquitoes use specific sensors around their mouths to detect carbon dioxide being exhaled from humans and animals.

But a few years ago, researchers from the University of California Riverside discovered the blood-sucking insects also use these same sensors to detect body odours – especially the smell of feet. 


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