Post-Treatment Surveillance for Lymphatic Filariasis in Plateau and Nasarawa States, Nigeria: Results of Transmission Assessment Surveys

Am J Trop Med Hyg. 2020 Jun;102(6):1404-1410. doi: 10.4269/ajtmh.20-0020.

Abstract

Following the halt of mass drug administration (MDA) for lymphatic filariasis (LF), the WHO recommends at least 4 years of post-treatment surveillance (PTS) to confirm that transmission recrudescence or importation does not occur. The primary means of evaluation during PTS is repeated transmission assessment surveys (TASs) conducted at 2- to 3-year intervals after TAS-1 stop-MDA surveys. This study reports the results of TAS-2 and TAS-3 surveys in Plateau and Nasarawa states (pop. 6.9 million) of Nigeria divided into a minimum of seven evaluation units (EUs) per TAS. A total of 26,536 first- and second-year primary school children (approximately 6-7 years old) were tested for circulating filarial antigen (CFA) between 2014 and 2017. Of 12,313 children tested in TAS-2 surveys, only five (0.04%) were CFA positive, with no more than two positive samples from any one EU, which was below the critical value of 20 per EU. Of 14,240 children tested in TAS-3 surveys, none (0%) were CFA positive. These results indicate that LF transmission remains below sustainable transmission levels and suggest that elimination of transmission has been achieved in Plateau and Nasarawa, Nigeria.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Albendazole / administration & dosage
  • Albendazole / therapeutic use*
  • Anthelmintics / administration & dosage
  • Anthelmintics / therapeutic use
  • Child
  • Child, Preschool
  • Elephantiasis, Filarial / epidemiology*
  • Elephantiasis, Filarial / prevention & control*
  • Female
  • Filaricides / therapeutic use
  • Humans
  • Ivermectin / administration & dosage
  • Ivermectin / therapeutic use*
  • Male
  • Mass Drug Administration*
  • Nigeria / epidemiology
  • Population Surveillance*
  • Retrospective Studies

Substances

  • Anthelmintics
  • Filaricides
  • Ivermectin
  • Albendazole