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What is MDA?

MDA is a campaign-style strategy used to administer drugs to at-risk populations in a given area, regardless of disease status. Because MDA is scalable and cost-effective, it has become a key tool to reduce disease occurrence and transmission in endemic areas and, in some cases, eliminate infections.1

MDA programs leverage technology to map and track disease, use data to measure impact, and identify missed opportunities for drug administration. MDA programs create awareness and mobilize entire communities. In the world’s most endemic areas, MDA is one of the most effective tools to reach the control and elimination goals set forth by WHO’s road map for neglected tropical diseases 2021–2030.2

MDA implementation follows a six-step process, with three broad stages:

  1. Pre-MDA—Preparing and gathering stakeholder momentum for the MDA campaign.
  2. MDA—Annual administration of preventive chemotherapy to the target population.
  3. Post-MDA—Monitoring and evaluating the performance of the MDA campaign.

Three stages of MDA implementation process

WHO (2021)

Globally, preventive chemotherapy delivered through MDA programs is the primary tool used in the control and elimination of many neglected tropical diseases. Lymphatic filariasis, commonly known as elephantiasis, is caused by parasite worms and transmitted through the bites of infected mosquitos.3 Mosquito-transmitted larvae enter the body and migrate to the lymphatic vessels where they develop into adult worms. Infection may occur at any age, but visible manifestations causing disability such as limbs edema may develop many years after infection. In 2021, lymphatic filariasis affects more than 893 million people in 49 countries throughout Asia, Africa, the Western Pacific, the Caribbean, and South America.4

The role of MDA in lymphatic filariasis elimination is to reduce the prevalence of infection in the community to levels below 1 percent. This is accomplished through a two-drug regimen administered annually for at least five years, or through a three-drug regimen administered annually for at least two years.5 Once these treatments reduce transmission in at-risk endemic regions to target thresholds, transmission of lymphatic filariasis cannot be sustained and the infection is eliminated.

Transmission assessment surveys are a decision-making tool used to define endpoints for MDA. The first transmission assessment survey occurs at the end of the MDA stage to determine whether a series of MDA rounds have successfully reduced the transmission of lymphatic filariasis in endemic areas to a level low enough that it cannot be sustained even in the absence of drug intervention.6, 7

Transmission assessment surveys are conducted at the implementation unit (IU) level, which is the smallest administrative unit (district, town, city, or block) responsible for implementing MDA.6  According to the World Health Organization (WHO),8 an IU needs to meet the following criteria to be eligible for transmission assessment surveys:

  • At least five rounds with the two-drug regimen (or fewer with the three-drug regimen) have been implemented.
  • Drugs are administered to over 65 percent of the total population of the IU.
  • The prevalence of infection in sentinel and spot-check sites is below 1 percent (for the presence of microfilariae) or below 2 percent (for the presence of antigen using immunochromatographic tests).

In transmission assessment surveys, children aged six to seven years are tested to see if they have been exposed to the parasite. Prevalence of antigenemia below a critical level signifies transmission has stopped and the community is no longer at a public health risk for lymphatic filariasis. Once an IU has passed its first transmission assessment survey, MDA is no longer implemented, and the IU enters the post-MDA surveillance stage. In this stage, the impact of MDA or the elimination of transmission is validated by two more assessment surveys at an interval of two to three years.3

  1. 1
    Webster JP, Molyneux DH, Hotez PJ, Fenwick A. The contribution of mass drug administration to global health: past, present and future. Philos Trans R Soc Lond B Biol Sci. 2014;369(1645):20130434. https://doi.org/10.1098/rstb.2013.0434
  2. 2
    World Health Organization (WHO). Ending the Neglect to Attain the Sustainable Development Goals: A Road Map for Neglected Tropical Diseases 2021−2030. Geneva: WHO; 2021. Accessed May 13, 2021. https://www.who.int/publications/i/item/9789240010352
  3. 3
    Neglected tropical diseases. World Health Organization website. Accessed May 12, 2021. https://www.who.int/data/gho/data/themes/neglected-tropical-diseases
  4. 4
    World Health Organization (WHO). Lymphatic filariasis: key facts. Published March 2, 2020. Accessed May 13, 2021. https://www.who.int/news-room/fact-sheets/detail/lymphatic-filariasis
  5. 5
    World Health Organization (WHO). Guideline: Alternative Mass Drug Administration Regimes to Eliminate Lymphatic Filariasis. Geneva: WHO; 2017. Accessed May 12, 2021. https://apps.who.int/iris/bitstream/handle/10665/259381/9789241550161-eng.pdf?sequence=1
  6. 6
    Ottesen EA. Lymphatic filariasis: treatment, control and elimination. Adv Parasitol. 2006;61:395-441. https://doi.org/10.1016/S0065-308X(05)61010-X
  7. 7
    Stolk WA, Swaminathan S, van Oortmarssen GJ, Das PK, Habbema JD. Prospects for elimination of bancroftian filariasis by mass drug treatment in Pondicherry, India: a simulation study. J Infect Dis. 2003;188:1371-1381. https://doi.org/10.1086/378354
  8. 8
    World Health Organization (WHO). Transmission assessment surveys in the Global Programme to Eliminate Lymphatic Filariasis: WHO position statement. Geneva: WHO; 2012. Accessed May 12, 2021. https://apps.who.int/iris/bitstream/handle/10665/77690/WHO_HTM_NTD_PCT_2012_9_eng.pdf;jsessionid=1B27C9CE1214305FA1081263A70FF475?sequence=1
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