CHAPTER ONE

INTRODUCTION

The term “lymphatic filariasis” covers infections with three closely related nematode

worms- wuchereria bancrofti, Brugia malayi and brugia timori. All three infections are

transmitted to man by the bite of an infected mosquito through the skin.1 These larvae

then migrate to the lymphatic vessels and develop into adult worms, over a period of six

to twelve months, causing damage and dilatation of the lymphatic vessels. The filariae

live for several years in the human host. During this period they produce millions of

immature microfilaria that circulate in the peripheral blood and are ingested by

mosquitoes when they bite infected humans. The larval forms further develop inside the

mosquitoes before becoming infectious to man. Thus a cycle of transmission is

established.2,3,4

Lymphatic Filariasis is a global Public Health problem with eighty-three countries

endemic for the disease. There are approximately 1.1 billion people at risk for contracting

lymphatic filariasis and 120 million people are infected world-wide. 5 The disease is the

second most common vector borne parasitic disease after malaria. It is also the second

most common cause of long term disability after mental illness. One third of infected

people live in India, one third in Africa, the remainder live in the Americas, the Pacific

Island, Papua New Guinea and S.E. Asia.6

Four countries- India, Indonesia, Nigeria and Bangladesh account for 70% of all

Lymphatic filariasis. infections. Nigeria is the third most endemic country in the world

for the disease, with an estimated 22 million cases. Estimates of annual economic loss in

India due to the disease approach 1 billion U.S. dollars; the economic impact in Nigeria is

unknown but expected to be significant.7

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In communities where the disease is endemic as many as 10 percent of women can be

affected with swollen limbs and 50 percent of men can suffer from mutilating genital

symptoms.8 Filariae are responsible for a variety of clinical manifestations including

lymphoedema of the limbs, genital disease (hydrocele, chylocele and swelling of the

scrotum and penis) and acute recurrent secondary bacterial infections known as “acute

attacks”. The vast majority of infected are asymptomatic but virtually all of them have