Fortunately, serious mosquito-borne diseases are uncommon in Shanghai, but they are by no means absent. Summer is when Shanghai and other cities see a peak in cases of encephalitis, an uncommon but very serious disease often transmitted by mosquito bites.

    Even without serious illness, mosquito bites exact a health toll. Children often scratch bites sufficiently to cause bleeding or infection.

    When outdoors, stay away from areas where mosquitoes concentrate, especially during the evening. Protect skin by using clothing and repellent. Keep areas such as porches, balconies or yards mosquito-free with repellent candles or inexpensive bug zappers.

    Three classes of mosquito repellents exist, and in most situations, it is wise to use two for complete protection.

    DEET is the most effective and widely recommended repellent, protecting the longest when applied to skin, clothing, or bedding. Be forewarned that it is toxic when swallowed and irritating to the eyes, so take care when applying to children.

    With young children there is concern that it could be absorbed through the skin, so only use on clothing of children under one year of age. DEET should be washed off the skin upon returning indoors.

    Safer, but less effective than DEET, natural (non-pesticide) repellents generally contain citronella or eucalyptus. More frequent application is necessary, so re-apply natural repellents every two hours for maximum protection.

    Permethrin is an insecticide and insect repellent that can be used to treat clothing or bed nets, but it should not be applied directly to the skin. Being relatively non-toxic, it will remain on clothing through several washings.

    Exercise caution, however, when using insecticide repellents. Do not spray in an enclosed area, apply to the face or inhale vapors. Also, take special care when using insecticide sprays around asthmatic children.

    It is recommended that repellents not be applied to broken or blistered skin, and that they are only to be used on exposed skin or on the outside of clothing.

    Adults should apply repellent to children under 10 years of age.

    When it comes to first aid for mosquito bites, don't scratch. Scratching starts the cycle where more and more histamine and inflammation are seen in the skin followed by worse itching.

    Treat a fresh bite with a single application of topical steroid cream is recommended for infants and young children. Oral antihistamines can help reduce itching and scratching, the usual cause of infection from bites.