By . Jenny Hope Medical Correspondent . Travellers to exotic places should use repellents containing DEET to protect against insect bites - as the benefits outweigh the risks, say experts. British experts are backing the insecticide despite safety concerns. They say more harm occurs when people use too little DEET and put themselves at greater risk of potentially harmful diseases such as malaria and dengue fever. Experts believe that travellers to exotic locations should use insect repellent containing DEET as the benefits outweigh any potential side effects (picture posed by model) Latest figures suggest the number of visits by Britons to tropical countries went up by two million between 2002 and 2012 – from 4.02m to 6.03m. Previous research has questioned the safety of DEET, which contains N,N-diethyl-m-toluamide and was developed by the US army for jungle warfare just after World War II. It is the active ingredient in many commercial topical repellents sold today. However, some governments limit its concentration after reports of a type of brain disease called encephalopathy following DEET use. Dr James Logan, senior lecturer in medical entomology at the London School of Hygiene & Tropical Medicine, recommends using repellents containing 20-50 per cent DEET in tropical countries. He said ‘If DEET products are restricted to just 15 per cent, it is likely that millions of people will be put at greater risk of mosquito bites which will dramatically increase their likelihood of developing a disease like malaria or dengue as a result. ‘There is plenty of evidence to show that low levels of DEET are not very effective, so it is important that travellers have access to repellents with greater levels of DEET that will provide the best protection.’ Dr James Logan said people should use repellents containing between 20-50 per cent DEET to counter the threat of mosquito bites . A new review of existing studies headed by Dr Logan concludes there is insufficient evidence to show that DEET is unsafe for human use. The review, published in the open access journal Parasites and Vectors (must credit), found the benefits of avoiding disease-spreading insect bites outweigh any risks associated with applying DEET to the skin. It discovered only one existing human trial on the safety of DEET, in pregnant women in Thailand. This study compared women who used a DEET-based repellent to prevent malaria transmission to a control group. There was evidence of traces of DEET in the children, suggesting that the substance could cross the placental barrier, but, crucially, no differences in the health of the babies between the DEET treatment group and the control group babies. The review also looked at existing animal studies to assess the safest amount of DEET to use in repellents and found that insufficient evidence had been gained from these to justify any imposed limits on concentration of DEET. Based on this, the authors weigh the safety risks found in trials against the protection that DEET-based repellents give against transmission of diseases. Dr Logan said the best protection against insect-borne illness was to avoid getting bitten, but repellent played an important part in reducing the burden of illness. He said ‘Our review article found very few studies that suggested any adverse effect of DEET. ‘In fact, there were only 14 cases of encephalopathy associated with DEET since 1957 which is extremely small considering the estimated 200 million applications of DEET to the skin each year. ‘If DEET caused serious health problems, we would know about it by now.’ A spokeswoman for the London School of Hygiene and Tropical Medicine said dengue fever -  a viral infection that is transmitted to humans by Aedes mosquitoes - is present in Brazil where football fans from around the world are due to converge for the world cup. It can cause life-threatening illness and there is there is no cure and no vaccine against it. The main protection against dengue fever is insect repellents, she said. ‘Biting arthropods can transmit a whole range of diseases to humans and it is vital to protect ourselves’ added Dr Logan. ‘Vaccines and treatments are available for some diseases, but not all, and so the best way to keep as safe as possible is to use an insect repellent containing DEET and reapply it regularly. ‘We want people to enjoy their holidays and tropical trips - we don’t want them ruined by illness so we want to do all we can to help inform and educate people about the facts rather than the many myths surrounding this issue’ he said.
Travellers to exotic locations should use spray containing at least 20 per cent DEET .
Experts warn that 15 per cent DEET puts millions of people at mosquito risk .
The best defence is to avoid getting bitten but repellents can be effective .
By . Jenny Hope Medical Correspondent . Travellers to exotic places should use repellents containing DEET to protect against insect bites - as the benefits outweigh the risks, say experts. British experts are backing the insecticide despite safety concerns. They say more harm occurs when people use too little DEET and put themselves at greater risk of potentially harmful diseases such as malaria and dengue fever. Experts believe that travellers to exotic locations should use insect repellent containing DEET as the benefits outweigh any potential side effects (picture posed by model) Latest figures suggest the number of visits by Britons to tropical countries went up by two million between 2002 and 2012 – from 4.02m to 6.03m. Previous research has questioned the safety of DEET, which contains N,N-diethyl-m-toluamide and was developed by the US army for jungle warfare just after World War II. It is the active ingredient in many commercial topical repellents sold today. However, some governments limit its concentration after reports of a type of brain disease called encephalopathy following DEET use. Dr James Logan, senior lecturer in medical entomology at the London School of Hygiene & Tropical Medicine, recommends using repellents containing 20-50 per cent DEET in tropical countries. He said ‘If DEET products are restricted to just 15 per cent, it is likely that millions of people will be put at greater risk of mosquito bites which will dramatically increase their likelihood of developing a disease like malaria or dengue as a result. ‘There is plenty of evidence to show that low levels of DEET are not very effective, so it is important that travellers have access to repellents with greater levels of DEET that will provide the best protection.’ Dr James Logan said people should use repellents containing between 20-50 per cent DEET to counter the threat of mosquito bites . A new review of existing studies headed by Dr Logan concludes there is insufficient evidence to show that DEET is unsafe for human use. The review, published in the open access journal Parasites and Vectors (must credit), found the benefits of avoiding disease-spreading insect bites outweigh any risks associated with applying DEET to the skin. It discovered only one existing human trial on the safety of DEET, in pregnant women in Thailand. This study compared women who used a DEET-based repellent to prevent malaria transmission to a control group. There was evidence of traces of DEET in the children, suggesting that the substance could cross the placental barrier, but, crucially, no differences in the health of the babies between the DEET treatment group and the control group babies. The review also looked at existing animal studies to assess the safest amount of DEET to use in repellents and found that insufficient evidence had been gained from these to justify any imposed limits on concentration of DEET. Based on this, the authors weigh the safety risks found in trials against the protection that DEET-based repellents give against transmission of diseases. Dr Logan said the best protection against insect-borne illness was to avoid getting bitten, but repellent played an important part in reducing the burden of illness. He said ‘Our review article found very few studies that suggested any adverse effect of DEET. ‘In fact, there were only 14 cases of encephalopathy associated with DEET since 1957 which is extremely small considering the estimated 200 million applications of DEET to the skin each year. ‘If DEET caused serious health problems, we would know about it by now.’ A spokeswoman for the London School of Hygiene and Tropical Medicine said dengue fever -  a viral infection that is transmitted to humans by Aedes mosquitoes - is present in Brazil where football fans from around the world are due to converge for the world cup. It can cause life-threatening illness and there is there is no cure and no vaccine against it. The main protection against dengue fever is insect repellents, she said. ‘Biting arthropods can transmit a whole range of diseases to humans and it is vital to protect ourselves’ added Dr Logan. ‘Vaccines and treatments are available for some diseases, but not all, and so the best way to keep as safe as possible is to use an insect repellent containing DEET and reapply it regularly. ‘We want people to enjoy their holidays and tropical trips - we don’t want them ruined by illness so we want to do all we can to help inform and educate people about the facts rather than the many myths surrounding this issue’ he said.
to exotic places should use repellents containing travellers to exotic locations should use insect is likely that millions of people will be put at 20-50 per cent DEET to counter the threat of was to avoid getting bitten, but repellent played