Lymphatic filariasis is a parasitic infection that can result in an altered lymphatic system and the abnormal enlargement of body parts, causing pain, severe disability and social stigma. Infection occurs when filarial parasites are transmitted to humans through mosquitoes. Mosquitoes can become infected with microfilariae by ingesting the blood of an infected host.
Lymphatic filariasis infection involves asymptomatic, acute and chronic conditions. The majority of infections are asymptomatic, showing no external signs of infection, but they still cause damage to the lymphatic system and the kidneys as well as alter the body’s immune system. When lymphatic filariasis develops into chronic conditions, it leads to lymphoedema (tissue swelling) or elephantiasis (skin/tissue thickening) of limbs and hydrocele (scrotal swelling). Involvement of breasts and genital organs is common.
In 1997, the Fiftieth World Health Assembly adopted resolution WHA50.29 to encourage Member States to eliminate lymphatic filariasis as a public health problem. In response, WHO launched its Global Programme to Eliminate Lymphatic Filariasis (GPELF) in 2000 with the aim of eliminating the disease as a public health problem. In 2012, WHO reconfirmed the target date for achieving global elimination as 2020. WHO’s strategy is based on two key components: (1) stopping transmission through large-scale annual treatment of all eligible people in an area or region where infection is present; and (2) alleviating the suffering caused by lymphatic filariasis through increased morbidity management and disability prevention activities.
In the Western Pacific Region, 22 countries and areas are considered endemic with lymphatic filariasis. Eleven countries and areas (American Samoa, Cambodia, Cook Islands, Marshall Islands, Niue, New Caledonia, Palau, Tonga, Vanuatu, Viet Nam and Wallis and Futuna) are in the post-intervention surveillance phase, while the other 11 countries and areas are progressively implementing mass drug administration.