Soil Transmitted Helminths (STH) such as Ascaris lumbricoides, hookworms, and Trichuris trichiura are intestinal parasites that require fecal contamination of the environment for transmission. The number of infected individuals worldwide for Ascaris, hookworm and Trichuris are estimated to be 1000 million, 650 million, and 700 million, respectively. These parasites have their highest health impacts in children; they impair growth, retard cognitive development, and cause severe anemia.
Drugs used for other parasitic infections: lymphatic filariasis and onchocerciasis through mass drug administration (MDA) programs are also active against STH. Suppression of STH is an important ancillary benefit of MDA programs.Conventional de-worming campaigns usually target school-aged children, and they have limited impact on transmission. The DOLF project is studying the effects of treating total populations to test whether MDA can reduce STH infection intensities and reinfection rates. In addition, DOLF is using the routine assessments of treatment for sample collection to improve the diagnosis of STH (Fischer et.al. 2018, Rosa et.al. 2018).
Effect of Semiannual vs Annual MDA for LF on
Studies in Liberia (2 sites), Cote d’Ivoire, Indonesia and PNG indicate that in some areas MDA reduces the density of STH infection and may temporarily reduce prevalence. However, 12 months after the last MDA the difference between semiannual and annual MDA has mostly vanished. The effect of MDA to eliminate LF and Oncho on STH appears variable and to depend on pretreatment prevalence and the local epidemiology.
Effect of Semiannual MDA with Albendazole on STH
Semiannual MDA with Albendazole is effective in reducing STH. Studies from the Republic of Congo indicated in areas with low hookworm prevalence it may be even possible to eliminate this infection (Pion et. al. 2017, 2015).
Effect of IDA for LF on STH
Studies on the effect of IDA on STH are currently performed in eastern Indonesia and Papua New Guinea. Since ivermectin has been rarely used in for MDA in this part of the world we expect exciting new results.