Dr Jack A T Edmonds MB BS FRCGP

Private General Practitioner

Your Health in Our Hands

120 Harley Street
London
W1G 7JW

Phone: 020 7935 5050
Fax: 020 7935 3888
Email: enquiry@drjackedmonds.co.uk

Beware the humble Mosquito!

As we take off for adventurous holidays across the globe this year it would be worth considering the role of the mosquito in the spread of disease and sometimes death. Worldwide this infuriating insect is responsible for millions of cases of malaria, dengue fever, chikungya, yellow fever and most recently zika virus ( in Brazil and the Amazon).  These diseases are important drains on the resources of local people but also affecting travellers from first world countries with increasing frequency.

Travellers can be protected against yellow fever by vaccination at least 10 days before departure. You can be protected from malaria by taking the right oral medication starting a day or two before departure and continuing daily dosage for up to a month after returning home. You will need to consult Dr Jack to learn about International Certification for yellow fever and whether the country you are visiting has a malaria risk and which medication to take.

All the other diseases spread by the humble moZZie have no vaccination and no effective treatment. Your business trip or holiday and indeed your long term health could be ruined by one moZZie attack, so, when you go abroad, check with us about the risks you might encounter and take bite protection precautions -

Mosquitoes are attracted by several factors, including the presence of carbon dioxide, heat, odours and movement. The female mosquito requires a blood meal in order to reproduce. There are many mosquito species; some species bite during daylight hours (e.g. Aedes spp.), and some are more active from dusk to dawn (e.g. Anopheles spp.)

Don`t let the humble mosquito scare you away from the trip of a lifetime but do take simple precautions and enjoy a healthy holiday.

Personal protection measures during travel

Behaviour

  • Be aware of the risk.
  • Try to avoid areas known to be heavily infested with mosquitos.

Clothing

When travelling in areas with malaria it is advisable to wear loose-fitting clothes with long trousers and long sleeves in the evenings. Travellers to areas with a risk of dengue fever infection should cover up during the day if possible, as the Aedes spp. mosquitoes that transmit dengue fever bite during the day.

In tick-infested areas, trousers should be tucked into socks to prevent ticks from crawling up the legs.

Avoid dark blue clothing when travelling in Africa in areas where tsetse flies exist.

Clothing can be treated with an insecticide (e.g. permethrin), which kills insects, including ticks, on contact. Permethrin is available in formulations designed to be sprayed on to clothing.

Insect repellent: General information

N, N-diethylmetatoluamide (DEET) based repellents are the most effective [1]; they have been widely tested under field conditions, and have been used for more than 50 years. DEET is available in several concentrations. Concentrations of 20% have been shown to offer protection for 1-3 hours, and higher concentrations provide longer-lasting protection [2]. As the duration of protection plateaus at concentrations higher than 50%, there is no need to use repellents with concentrations greater than 50% [2].

DEET-containing preparations should not be used in babies younger than 2 months of age. They can be used in concentrations up to 50% in pregnant or breast-feeding women, and in infants and children older than 2 months. Manufacturers in the UK have applied their own age restrictions, however, there is no evidence that using DEET on infants and children older than 2 months causes harm. Care should be taken to ensure that repellents are not ingested, and that they do not come into contact with the eyes or mouth.

Repellents should be reapplied at regular intervals, after swimming and in hot, humid conditions when they may be removed by perspiration. When both sunscreens and repellents are used, the repellent should be applied over sunscreen [3].

Research and extensive clinical experience indicate that DEET is very safe when used according to the manufacturer’s instructions [2].

  • Insect repellent: Advice for travellers
  • Use only on exposed areas of skin.
  • Remove with soap and water when the repellent is no longer needed.
  • Do not spray directly on the face, and wash hands after application to avoid contact with lips and eyes.
  • Do not apply to cuts, abrasions or irritated skin.
  • Sunscreen that is combined with repellent should usually be avoided.

Picaridin (Autan®) and lemon eucalyptus extract (Mosiguard®) are available for those who prefer not to use DEET-based products [2, 4]. These repellents have compared favourably with DEET [1]. Picaridin should be used in concentrations of approximately 20%.

Follow manufacturer’s instructions when applying repellents to babies and infants.

Screening and mosquito nets

Travellers staying in accommodation without screening should sleep under a net to avoid being bitten at night.

Mesh size in mosquito bed nets should be no larger than 1.5 mm.

Nets should be impregnated with permethrin (or other contact insecticides); most nets have been treated prior to purchase. Nets may need to be impregnated with permethrin again after six months of use; long-lasting insecticide nets will generally not need treating frequently [5].

Contact insecticides will kill insects landing on the net and therefore increase the effectiveness.

Travellers can carry a small sewing kit so that repairs can be made if the net develops a hole.

Other preventative measures

Knock down sprays that are designed to kill flying insects are not likely to provide sufficient protection from either nuisance biting or malaria prevention [1].

A systemic review demonstrated that mosquito coils can decrease bites by repelling and killing mosquitoes [6]. Coils, which contain synthetic insecticide, may be useful for some travellers but they should only be used outdoors [2].

Measures that cannot be recommended for repelling insects

These measures are not recommended:

  • Bath oil
  • Citronella oil-based repellents (these have very short durations of action)
  • Citrosa plant (geranium)
  • Garlic: fresh or capsules
  • Vitamin B12 complex
  • Yeast extract spread
  • Electronic (ultrasonic) buzzer devices
  • Vitamin B1 tablets
  • Tea tree oil

Treatment of insect/tick bites

Arthropod bites usually appear as small, red, raised papules that itch. Application of a cold compress to the bite site may provide relief from pain or itching [7-8].

Local swelling can be reduced by the topical application of a mild steroid cream. Antihistamine tablets can be taken to relieve itching.

Mosquito bites should not be scratched and should be kept clean and dry to avoid infection.

Ticks need to be removed from the skin very carefully. This can be done with tweezers or specially designed tick removers. Grasp the tick near to the skin and steadily pull out the tick being careful not to crush the tick’s body or squeeze the stomach contents into the site of the bite. Illustrated instructions are available.

Don`t let the humble mosquito scare you away from the trip of a lifetime but do take simple precautions and enjoy a healthy holiday.

News - BBC Health