One of the diseases on the list is Onchocerciasis (River blindness) which can be found in Western and Central Africa, six countries in Latin America, Brazil and Yemen. It is an insect borne disease caused by a parasite Onchocera volvulus and is transmitted by blackflies who commonly live and breed beside fast flowing rivers. After being bitten by the flies, infective adult worms develop and fertilised female larvae release microfilariae which migrate to the host’s skin, causing irritation and scratching and secondary infection often follows. They can also cause lesions around the eye where they can cause inflammation, bleeding and eventually blindness. These microfilariae are then taken up by the blackflies again and so the disease spreads.
Widespread spraying with insecticide at breeding sites is happening in many countries and there is now a drug treatment called Ivermectine 150mg/kg which is given by mouth once a year. This makes the female parasitic worms infertile but only temporarily and so treatment may need to be given for several years. Since 1996 mass community-based treatment programmes have been introduced in Africa and Latin America.
Travellers should avoid where possible camping or living near rivers. Those travellers who will be living or working in affected countries are most at risk and should take good bite avoidance measures. These include 40-50% DEET repellents, EX4 clothing spray, keeping skin covered with long sleeved, loose, light coloured clothing, including socks and using impregnated nets such as those on sale at The Travel Clinic Ltd.
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