title: Sustained reduction in prevalence of lymphatic filariasis infection in spite of missed rounds of mass drug administration in an area under mosquito nets for malaria control.
abstract: BACKGROUND
  The Global Programme to Eliminate Lymphatic Filariasis (GPELF) was established by the World Health Organisation (WHO) in 2000 with the goal of eliminating lymphatic filariasis (LF) as a public health problem globally by 2020. Mass drug administration (MDA) of antifilarial drugs is the principal strategy recommended for global elimination. Kenya launched a National Programme for Elimination of Lymphatic Filariasis (NPELF) in Coast Region in 2002. During the same year a longitudinal research project to monitor trends of LF infection during MDA started in a highly endemic area in Malindi District. High coverage of insecticide treated nets (ITNs) in the coastal region has been associated with dramatic decline in hospital admissions due to malaria; high usage of ITNs is also expected to have an impact on LF infection, also transmitted by mosquitoes.
  
  
  RESULTS
  Four rounds of MDA with diethylcarbamazine citrate (DEC) and albendazole were given to 8 study villages over an 8-year period. Although annual MDA was not administered for several years the overall prevalence of microfilariae declined significantly from 20.9% in 2002 to 0.9% in 2009. Similarly, the prevalence of filarial antigenaemia declined from 34.6% in 2002 to 10.8% in 2009. All the examined children born since the start of the programme were negative for filarial antigen in 2009.
  
  
  CONCLUSIONS
  Despite the fact that the study villages missed MDA in some of the years, significant reductions in infection prevalence and intensity were observed at each survey. More importantly, there were no rebounds in infection prevalence between treatment rounds. However, because of confounding variables such as insecticide-treated bed nets (ITNs), it is difficult to attribute the reduction to MDA alone as ITNs can lead to a significant reduction in exposure to filariasis vectors. The results indicate that national LF elimination programmes should be encouraged to continue provision of MDA albeit constraints that may lead to missing of MDA in some years.
authors: Kenya Medical Research Institute (KEMRI), Nairobi, Kenya. sammynjenga@gmail.com
authors: Sammy M
authors: SM
authors: Njenga
authors: Charles S
authors: CS
authors: Mwandawiro
authors: C Njeri
authors: CN
authors: Wamae
authors: Dunstan A
authors: DA
authors: Mukoko
authors: Anisa A
authors: AA
authors: Omar
authors: Masaaki
authors: M
authors: Shimada
authors: Moses J
authors: MJ
authors: Bockarie
authors: David H
authors: DH
authors: Molyneux
references: Trans R Soc Trop Med Hyg. 2007 May;101(5):439-44
references: 17145069
references: PLoS Negl Trop Dis. 2009 Aug 25;3(8):e443
references: 19707279
references: PLoS Negl Trop Dis. 2010 Mar 23;4(3):e640
references: 20351776
references: PLoS Negl Trop Dis. 2008;2(12):e344
references: 19065257
references: Ann Trop Med Parasitol. 2002 Dec;96 Suppl 2:S91-5
references: 12625922
references: Trans R Soc Trop Med Hyg. 1988;82(5):721-5
references: 3075358
references: Bull World Health Organ. 1997;75(6):491-503
references: 9509621
references: Annu Rev Entomol. 2009;54:469-87
references: 18798707
references: Am J Trop Med Hyg. 2008 Oct;79(4):480-4
references: 18840733
references: Filaria J. 2003 Jul 7;2(1):11
references: 12890288
references: Am J Trop Med Hyg. 2000 Mar;62(3):363-7
references: 11037778
references: PLoS Med. 2007 Aug;4(8):e255
references: 17713981
references: Trans R Soc Trop Med Hyg. 2008 Oct;102(10):1017-24
references: 18550135
references: Ann Trop Med Parasitol. 2007 Mar;101(2):161-72
references: 17316502
references: Ann Intern Med. 2007 Oct 16;147(8):W163-94
references: 17938389
references: J Parasitol. 1990 Feb;76(1):78-84
references: 2405144
references: J Infect Dis. 1994 Jul;170(1):247-50
references: 8014511
references: Ann Trop Med Parasitol. 1979 Oct;73(5):457-64
references: 393190
references: Parasitology. 2008 Nov;135(13):1583-98
references: 19006602
references: Lancet. 2008 Nov 1;372(9649):1555-62
references: 18984188
references: Malar J. 2007 Nov 15;6:151
references: 18005422
references: Adv Parasitol. 2006;61:395-441
references: 16735170
references: Trans R Soc Trop Med Hyg. 2002 Apr;96 Suppl 1:S225-9
references: 12055843
references: Southeast Asian J Trop Med Public Health. 1975 Sep;6(3):430-4
references: 3855
references: Lancet. 2006 Mar 25;367(9515):992-9
references: 16564361
references: Ann Trop Med Parasitol. 1981 Aug;75(4):415-31
references: 6118103
references: Ann Trop Med Parasitol. 1977 Sep;71(3):313-31
references: 335990
references: East Afr Med J. 1997 May;74(5):288-93
references: 9337005
references: Wkly Epidemiol Rec. 2006 Jun 2;81(22):221-32
references: 16749186
references: Filaria J. 2004 Sep 3;3(1):9
references: 15347425