Filarial Worms in Southeast Asia

Abstract

The lymphatic filariae, namely Brugia malayi, B. timori and Wuchereria bancrofti, are of medical importance in Southeast Asia. Brugian filariasis is predominant in Indonesia, Malaysia, Brunei Darussalam and Vietnam; bancroftian filariasis is common in Lao PDR, Philippines and Myanmar, while both types of filariasis are found in Cambodia, Southern Philippines, Thailand and Timor Leste. The Global Programme for the Elimination of Lymphatic Filariasis (GPELF) began in year 2000 and targeted to be achieved by 2020. These countries are at different phases of the programme, and most are showing successes in terms of health and economic benefits. The traditional thick blood smear examination using night blood is still being used for diagnosis; however, more sensitive, rapid and field-applicable tests that allow blood sampling at anytime of the day, such as Brugia Rapid and ICT card tests, are important tools for GPELF. An integral part of the programme is the mass drug administration (MDA) for a minimum of 5 years to stop transmission of the infection. It comprises an annual dose of diethylcarbamazine and albendazole, and in children this has also been shown to reverse the subclinical lymphatic pathology. The commonly recognised clinical manifestations of brugian filariasis are chronic lymphoedema of the limbs, which may lead to elephantiasis and repeated attacks of acute dermatolymphangioadenitis (ADLA). Limb hygiene is a simple and effective method for morbidity management to prevent ADLA and has become the mainstay for disability management in GPELF. The current trend is adoption of an integrated approach to the control of Neglected Tropical Diseases (NTD), such as combining elimination programmes for lymphatic filariasis and soil-transmitted helminths. In addition, a surveillance programme after elimination of lymphatic filariasis is crucial to prevent reemergence of this disease in the future.