A model for the control of soil-transmitted helminthiasis.

Periodic anthelmintic treatments was conducted at Elsie Gaches Village, the National Center for the Mentally Retarded, from Oct., 1986 to Aug., 1987 to test the hypothesis that mass drug administration at 2 month intervals for at least 10 months is an appropriate strategy for the control of soil-transmiitted helminthiases given a situation with polyparasitism, high infection rates, poor sanitation, and low level of health awareness in the population. The paper aims to assess the efficiency, i.e., the economic feasibility and public health significance of periodic mass deworming and to validate some of the factors affecting the success of intestinal parasite control Two mathematically-derived models of Hayashi were used to project the possible outcome of control given the combinations of a drug with relatively low cure rate, e.g. "niyog-niyogan", a herbal anthelmintic and high reinfection rates, and highly efficacious drug e.g. oxantel-pyrantel and/or mebendazole and low reinfection rates. Both models fitted the present strategy of control depending upon the choice of drugs and treatment regimens Ideally the intervals of treatment should coincide with the pre-patent period of parasite, and the duration of control, with their peculiar behavior in the body of the host and the persistence of infective stages in the environment. By and large, periodic mass deworming has improved the nutritional status of client residents at Elsie Gaches Village and reduced infection rates to 3.3 percent in ascariasis, 20.8 percent in trichuriasis, and 3.8 percent in hookworm infection; strongyloidiasis was completely eliminated In areas where proper laboratory facilities are lacking and where primary health care is established, periodic mass deworming with a relatively safe and inexpensive drug can be implemented without parasitologic examinations to minimize operational costs. Exacerbated disease due to multiple infections and severe malnutrition can be treated on a selective basis.(Author) http://www.psmid.org.ph/vol16/vol16num2topic7.pdf