April 24,2012

Bolivia Launches Pilot Program for Deworming

SEDES Health Personnel BoliviaIn 2011, Izumi Foundation awarded CWW a grant to help Bolivia's Ministry of Health and Sport (MSyD) develop and implement an STH control pilot project. The Pan American Health Organization (PAHO) was asked to participate in the project due to their success with a similar project done in 2008 to address fasciola infection. The STH control project, designed around the assumption that infection rates strongly relate to the ecological conditions of an area, will start by mapping "ecoregions." Then they will use the approach used by the fasciola project to demonstrate proof of concept in three different communities. Ultimately, the success of the project could lead to a longer-term commitment to STH control in Bolivia.


A 2008 report issued by the Pan American Health Organization (PAHO) indicated that STH infection rates in Bolivia ranged from 4.5 percent to 65.4 percent, depending on the ecoregion, or area of ecological similarity. It also revealed that school-age children suffer the highest rates of morbidity from infection, including anemia, stunted growth and reduced cognitive development, and that risk of infection rises to 50 percent or more for those living in the Amazon areas and river valleys.

In 2011, Children Without Worms was awarded a grant from the Izumi Foundation to support the efforts of the Bolivian Ministry of Health and Sport (MSyD) to control STH. The Izumi Foundation is a non-governmental organization (NGO) that strives to help the world’s poorest people improve their health. Their grant supports an STH control pilot project in three communities in Bolivia. The project will serve as a proof of concept that if successful, could be expanded to additional communities and eventually nationwide. 

This project is also being supported by PAHO. Dr. Fidel Villegas, National Officer in Veterinary Public Health at the PAHO office in Bolivia, serves as liaison between PAHO and the MSyD. In this role, he manages and monitors the implementation of the project objectives in the field. Dr. Villegas brings to the STH project his experience from a successful 2008 fasciola pilot project. In this project, they achieved a 77 percent cure rate for fascioloa after just a single dose of triclabendazole. Since 2008, they have administered doses of the medication to 150,000 people in La Paz, an area that is highly endemic for fasciola infection.

Mapping Prevalence by Ecoregion

PAHO’s 2008 report indicated that STH prevalence correlates strongly with ecoregion, so the first step of the project is to map STH prevalence in these regions. Mapping regions enables the project team to use statistical sampling to establish a baseline of prevalence by region. The baseline determines which ecoregions require mass drug administration and how many annual doses to administer based on WHO/PAHO guidelines (one dose per year where prevalence is between 20 percent and 50 percent, and two doses per year where it is above 50 percent).

Bolivia has several different ecoregions that range widely in climate, which include llanos and yungas (humid/tropical), altiplano (high desert), valleys (temperate), and chaco (sub-tropical/semi-arid). Dr. Villegas predicts, “Due to ecological conditions, areas such as altiplanos would need mass deworming once a year and llanos twice.” However, a treatment strategy will be finalized only after establishing the baseline. These baseline results will be extrapolated by ecoregion to municipalities within the same department.

[For more information on using ecoregions to determine disease prevalence, review the articles referenced at the end of this article.]

Establishing the Baseline and Administering Treatment

Bolivia, with a population of approximately 10 million, has nine departments with a total of 337 municipalities. Each municipality contains several communities. The health departments (SEDES) of La Paz, Potosi and Chuquisaca have each already identified a single community to participate in the pilot study. These communities were selected due to their location in the river and valley ecoregions where prevalence is assumed to be highest. They will select a larger school within the identified communities to measure and establish an STH prevalence baseline.

The project team will next administer an anthelminthic using the approach the fasciola pilot project used: MSyD distributes the medication to each SEDES, and each SEDES distributes it to the municipality. Health personnel in each municipality rely on schools to distribute the medication to school-age children. The selected schools will each have approximately 200 students, so he estimates they will treat around 600 children in the project’s first year.

Eventually, the team hopes to train teachers to distribute the medication along with health personnel. To Dr. Villegas, this makes sense because “teachers are interested in these programs. They know that the kids, mothers and families suffer daily from these types of diseases.” They also plan to complement deworming with activities such as “teaching washing hands and washing foods to prevent these [fasciola and STH] illnesses.”

Measuring Impact and Looking Ahead

Key to success of the project is showing proof to MSyD and the SEDES that the pilot project has been effective. Dr. Villegas hopes that “by 2014, MSyD will expand the drug distribution to reach 3.5 million school-age children.” He is confident that two years of the pilot project will provide enough evidence of success for MSyD to support a longer term program for mass drug administration to school-age children.

Dr. Villegas also believes that the success of this project will spark the involvement and interest of other sectors, such as the Ministries of Water, Environment and Education. He feels that “this common problem [STH infection] for school children can inspire [Ministries in multiple sectors] to join MSyD to fight STH and other NTDs in Bolivia.” To him, a multi-sectoral approach is critical for ensuring that gains in STH control from deworming are maintained through prevention of re-infection.

Additional Articles

1. Brooker S, et al: Tools from ecology: useful for evaluating infection risk models? Trends Parasitol. 2002 February; 18(2): 70–74.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3166848/

2. Hay SI, et al. Earth observation, geographic information systems and Plasmodium falciparum malaria in sub-Saharan Africa. Adv. Parasitol. 2000;47:174–215.

3. Rogers DJ. Satellites, space, time and the African trypanosomiases. Adv. Parasitiol. 2000;47:130–165.

4. Lindsay SW, Thomas CJ. Mapping and estimating the population at risk from lymphatic filariasis in Africa. Trans. R. Soc. Trop. Med. Hyg. 2000;94:37–44. [PubMed]

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