title: Lymphatic filariasis mapping by immunochromatographic test cards and baseline microfilaria survey prior to mass drug administration in Sierra Leone.
abstract: BACKGROUND
  National mapping of lymphatic filariasis (LF) was conducted using immunochromatographic tests (ICT) in 2005 to determine endemicity and geographic spread of the disease. A baseline microfilaria survey was then conducted to determine LF prevalence and microfilaria intensity.
  
  
  METHODS
  In 2005 1,982 persons of 15 years and over from 14 health districts were selected and fingertip blood samples were tested with ICT cards. In 2007-8 blood samples were taken between 10 p.m. and 2 a.m. and examined for microfilaria (mf) from 9,288 persons from 16 sentinel sites representing each district and 2 additional sites for districts with populations over 500,000 (Bo and Kenema).
  
  
  RESULTS
  The overall LF prevalence by ICT cards was 21% (males 28%, females 15%). All districts had a prevalence of Wuchereria bancrofti antigen > 1%. Distribution of LF prevalence showed a strong spatial correlation pattern with high prevalence in a large area in the northeast gradually decreasing to a relatively low prevalence in the southwest coast. High prevalence was found in the northeast, Bombali (52%), Koinadugu (46%), Tonkolili (37%) and Kono (30%). Low prevalence was found in the southwest, Bonthe (3%) and Pujehun (4%). The mf prevalence was higher in the northeast: Bombali, 6.7%, Koinadugu 5.7%, Port Loko 4.4% and Kono 2.4%. Overall there was a significant difference in mf prevalence by gender: males 2.9%, females 1.8% (p = 0.0002) and within districts in Kailahun, Kono, Port Loko, Moyamba and Koinadugu (all p < 0.05). The mf prevalence was higher in people > 20 years (2.5%) than in people ≤ 20 years (1.7%) (p = 0.043). The overall arithmetic mean mf density was 50.30 mf/ml among mf-positive individuals and 1.19 mf/ml in the population examined which varied significantly between districts.
  
  
  CONCLUSIONS
  The ICT results showed that LF was endemic nationwide and that preventive chemotherapy (PCT) was justified across the country. Both the ICT and microfilaraemia surveys found that prevalence was greater in males than females. The increase in microfilaraemia prevalence by age was evident when grouped as ≤ 20 versus > 20 years demonstrating early exposure. Baseline LF microfilaria load will be used to monitor PCT program progress.
authors.affiliation: National Neglected Tropical Disease Control Program, Ministry of Health and Sanitation, Freetown, Sierra Leone. josephbrimakoroma@yahoo.com
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Koroma
authors.forename: Momodu M
authors.initials: MM
authors.lastname: Bangura
authors.forename: Mary H
authors.initials: MH
authors.lastname: Hodges
authors.forename: Mohamed S
authors.initials: MS
authors.lastname: Bah
authors.forename: Yaobi
authors.initials: Y
authors.lastname: Zhang
authors.forename: Moses J
authors.initials: MJ
authors.lastname: Bockarie
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000818:Animals; D000947:Antigens, Helminth / Q000097:blood*; D003625:Data Collection; D003710:Demography; D004605:Elephantiasis, Filarial / Q000175:diagnosis / Q000453:epidemiology* / Q000469:parasitology; D005260:Female; D006801:Humans; D008297:Male; D008842:Microfilariae / Q000302:isolation & purification; D008875:Middle Aged; D015995:Prevalence; D017678:Sex Distribution; D012807:Sierra Leone / Q000453:epidemiology; D014958:Wuchereria bancrofti / Q000276:immunology* / Q000302:isolation & purification; D055815:Young Adult
chemical_list: D000947:Antigens, Helminth