LIST OF CONTENTS Page SUMMARY I 1.0 INTRODUCTION I 2.0 MATERIALS AND METHODS 2.1 Study Area 4 2.2 REMO Implementation 6 3.0 RESULTS AND DISCUSSION 8 4.0 REFERENCES l3 5.0 ACKNOWLEDGMENT t6 6.0 APPENDIX t7 6.I Mission Schedule t7 6 2 REMO Data 20 SUMMARY ln recognition of the obvious public health problem of onchocerciasis in Liberia, and the need to generate a comprehensive epidemiological data necessary for the successful implementation of this disease control through Community Directed lvermectin Distribution (CDTI) strategy, WHO African Program for Onchocerciasis Control (APOC) as a partner in the program in Africa sponsored this nation-wide Rapid Epidemiological Mapping of Onchocerciasis (REMO) in the country. With a good quantitative understanding of onchocerciasis and its vector species; and a sound knowledge of the geography of Liberia, a total of 12O villages were selected for this study. Of this, 21 (17 .5o/o) of the villages were inaccessible at the time of this exercise. Using community nodule rate as indicator of disease endemicity, randomly chosen residents farmers, aged >.20 years, especially males were clinically examined. A total of 99 accessible selected villages were examined. The present results showed that human onchocerciasis is endemic in Liberia, especially along fertile banks of the major rivers and their tributaries. These results are integrated into the Geographical lnformation System (GlS) and are presented to ensure adequate coverage of endemic areaslzones that require CDTI priority in the ongoing APOC partnership control strategy in the region. 1. INTRODUCTION Onchocerciasis (River blindness) is a chronic parasitic disease caused by filarial nematode, Onchocerca volvulus; and it is transmitted by black flies (simulium species). Onchocerciasis is known to be endemic in many areas of 26 tropical African countries (including Liberia), six South American countries and Yemen. Since 1947 (Stoll,1947), human onchocerciasis has been recognized as a disease of significant public health importance and an impediment to socioeconomic development in endemic areas (Nwoke, 1990; Molyneux & Davies, 1997). This I debilitating disease causes different types of characteristic ocular lesions, especially in endemic villages in the savanna belt of West Africa. These lesions, often lead to irreversible blindness in untreated patients, hence the name river blindness because these blindness cases are seen more in village settlements along the rivers (the breeding sites of vectors and high transmission foci of the disease). ln addition, onchocerciasis infection causes very severe and worrisome onchocercal skin diseases (OSD), disfiguring and embarrassing hanging groin and genital elephantiasis as well as other systemic complications. These non-ocular manifestations have recently been found to cause more burden than blindness in most endemic areas in Africa, especially in the rainforest belt. The history of human onchocerciasis in Liberia dates back to 1926 when the Harvard Expedition gave the first evidence of the disease occurrence in the country (Strong, 1936). This was strengthened by the work of Burch et al (1955) on "Onchocerciasis in Liberia". This among other works stimulated the studies of Miller & Gunders (1958); Miller &Franz (1958); Gunders & Neuman (1963); Reber & Hoeppli (1964) and Gratama (1966). All these earlier workers contributed tremendously to our initial knowledge of the disease prevalence and clinical complications in endemic communities. The studies of Frentzel-Beyme (1973, 1975) brought to focus a more global picture of onchocerciasis distribution and the associated severe ocular lesions in the country, especially among endemic communities of Bong and Montserrado Counties. These clinical results were confirmed by the entomological evaluation studies of Garms (1973, 1987). Other studies in Liberia include ocular onchocerciaisis and palpable and impalpable experiments in the hyperendemic rainforest areas (Albiez et al, 1981' Albeiz, 1983a, Schulz-Key & Albeiz, 1977) as well as the studies of Barbiers & Trips (1984) in the Harbel Firestone Rubber Plantation, Margibi County. 2 These studies among other publications and reports point to the fact that onchocerciasis is prevalent in Liberia. However a lot more epidemiological information is needed on the disease distribution and intensity in many counties and districts because results available indicate that many zones are yet unidentified and unstudied. This situation has therefore left the country with limited epidemiological baseline data. Such limited information on the disease intensity and pattern, no doubt has continued to affect the effective planning and implementation of any control measure in the country. Fortunately, WHO/APOC is committed through partnership with MOH and various national and international Non-governmental Development Organizations (NGDs) to control onchocerciasis in all endemic Africa countries outside Onchocerciasis Control Program (OCP). The strategy of this partnership is to put in place within the first five years of any project a sustainable control program; through Community Directed Distribution of lvermectin (CDTI). That is, community ownership of the program. To achieve this mission WHO/APOC requires comprehensive epidemiological data generated using a uniform standard or protocol in any endemic area. ln Liberia this sort of baseline data is limited if not absent, and this has made it difficult for WHO/APOC to initiate any CDT! project in the country. ln recognition of this obvious gap and the need to determine where CDTI strategy should be implemented in liberia, and at the same time ensure adequate coverage of all the endemic zones, WHO/APOC sponsored this nation-wide Rapid Epidemiological Mapping of Onchocerciasis (REMO), December 26, 1998 to February 9, 1999. J 2. MATERIALS AND METHODS 2.1 STUDY AREA 13 counties of the The nation-wide REMO exercise was carried out in all the states (since 1847)' Republic of Liberia. one of the oldest independent African (Hasselimann, '1979). The Liberia is rocated between ratitudes 4' 2' N and B' 30' N by Guinea in the north' study area is bordered on the northwest by sierra Leone, the country on the south and cote d'lvoire on the east. The Atlantic ocean borders in 1998, Liberia and southwest. with an estimated population of 2.72 million (42,OOO sq' Miles)' occupies a land area of 1 1 1 ,366 square kilometers in places by long The Liberian terrain is varied; the low sandy coast is backed promontories' Away from the narrow lagoons, and is interrupted at intervals by rock lnland, the western part coast, the land becomes rolling plain with many small hills. culminating is densely forested, mountainous terrain tending north-east-south-west, in mt Vuutivi, 1,300 meters (4,528ft)' rivers, is a low The central hinterland, roughly between the st. Paul and cesstos meters (600 - 2000 ft)' inland plateau, with heights ranging between 190 and 610 poorly drained swamps' Characterized by small hills encirculed by many sinuous, vivid excarpments, the most the plateau is set off from the coastal plain in places by the Capital City' notable being at Reputa, 105 km (65 miles) northeast of Monrovia' with forest' The eastern section of the country is rugged and covered wet and dry seasons' The climate of Liberia is warm all year round with a marked dry season is between The rainy season is between May and November; and the 5,210 mm (205 inches) December and April. The highest annual rainfall of about 4 LIBERIA G u inea Sie r;a Leone -;t-n,*-.),^"v--. _i 4, ? Lonta Zorzor h Zot , Z' 'Jene C6te a a Ecllc Y.1ll,, O 0 Gbanga dWoiie a t Sanoyre f ,rrnc o I "..+it'I Cara ysburg Tepctz o +^ Gonglcc a Atlantic fe Ocean Julrtoa Ttrtuko + l<Nclw Grcnd Ccss AFFTICA slA .o0. .oc 6ta + EotdatS + llatn augott Rerrwrys + AttOorts Metn rcacts o Aamondt Rtvats @ Iton ^APIfAL Saurrlo J- Sc.pgrts @ C) AFRICAE00KS U0 @ irang.nara (100 inches) o@urs at Robertsport and this decreases south-eastwards to 2540mm at cape Palmas and to 1780mm (70 inches on the central plateau. Maximum dry season rainfall occurs in June through september. sometimes there is short (August break) at the peak of rain (July - August)' Leone, The major river systems in Liberia are the Mano on the border with sierra All Lofa, st. Paul, st. John, cesstos and cavalla at the border with cote d'lvoire' which these river systems are oriented north-east-south-west except the Cavalla, rapids at the flows north-south. The rivers have numerals tributaries and are cut by points where the littoral plain joins the interior relief-creating numerous breeding The sites for the vector of human onchocerciasis (Garms and Vajlme, 1975). vegetation of Liberia is essentially tropical rain forest, with some trees attaining gives the inland heights of 60 meters (197 ft). The seasonal rhythm of the rains at the cavalla forest a semi-deciduous regime. The evergreen forests of the basin on the Guinean river and the stands in the Gola forest thin out inland, giving way, along border, to somewhat guinea savannas with forests on steep slopes and streams. similar parkland savanna exists on the sandy soils along the coast' and Belle There are about seven large nationalforest reserves in Liberia viz: Kpelle forest in Lofa County; Grebo forest in Grand Gedeh County; Sapo forest that is located in stretches from sinoe into Grand Gedeh county; Gola forest reserved lt is Grand Cape [Vlount while Krali national forest reserve is in Sinoe County. human important to point out here that these forest reserves have little or no setflements and are therefore more or less uninhabited areas in Liberia. 2.2 REMO IMPLEMENTATION The implementation of this study was commenced with high level advocacy and a mobilization, and theoretical and field practicum for the six-man NOTF team, geographer and county health coordinators. (see appendix for the scheudle). The 6 team was exposed to all the important aspects of the disease and the vectors as well as REMO protocol (Ngoumou & walsh, 1993; WHO, 1992,1995).