African Programme for Onchocerciasis Control (APOC)

Assessing the health impact of APOC’s operations

Between 1999 and 2005, epidemiological evaluations showed a significant reduction in the prevalence of live microfilaria (larval forms of the Onchocerca volvulus parasite) in the eye. They also indicated that ivermectin treatment can prevent onchocercal blindness and severe itching.

Rapid health impact assessment

In 2007, a rapid health impact assessment of APOC was completed. The study aimed to assess the impact of APOC on skin and eye problems and on the burden of disease caused by onchocerciasis (measured in DALYs – disability adjusted life years lost due to the disease). A second objective was to predict the health impact of APOC by 2015.

Before the start of APOC:

  • 400 000 people in APOC countries were blind because of onchocerciasis
  • 900 000 people in APOC countries had low vision
  • 15.3% of people in APOC countries suffered from a troublesome itch.

The computer simulation model ONCHOSIM was used to simulate how the prevalence of infection and disease decline, depending on the number of treatment rounds provided and the proportion of people treated per round.

Reductions in symptoms and infection

By 2005, all symptoms had decreased (see graph). The prevalence of infection had declined to about 73% of its level prior to community-directed treatment with ivermectin (CDTI). It is predicted to decline to 14% of the pre-CDTI level by 2015.

The prevalence of itching had halved by 2005 and is predicted to be almost eliminated by 2015. Reduction in blindness and low vision is slower because of the irreversibility of these symptoms. These were reduced to 77% and 88% of the pre-CDTI levels respectively in 2005, and are predicted to reduce to 32% and 49% by 2015.

Reduction in burden of disease

In 2005, the annual number of DALYs lost had almost halved. By 2015, it is predicted that the reduction in DALY loss will be 86%.

Estimated prevalence of onchocerciasis infection and clinical manifestations in the APOC population in 2005 and 2015, compared to the pre-APOC level