During the phase of recruitment to the study cohort, villages in the province were selected for participation and the eligible population (35 years and older) recruited during 2–3 weeks of fieldwork. All 20 districts were included. Initially, one subdistrict was selected from each at random, and one of the villages within it chosen, based on the recommendation of the local health personnel (to maximize compliance). Later, for some districts, screening took place in all subdistricts; or, in other districts, all of the villages in the chosen subdistrict were screened. For some districts, more than one subdistrict was sampled. As a result, the sampling fraction by district was quite variable, and the time period during which the populations of different districts were tested was quite different.
During study recruitment, the head of the village was contacted and the aim of the intervention explained. Lists of the resident population were obtained and files of eligible people prepared. The study team visited the village, with a mobile unit equipped with an ultrasound machine. The unit was then installed in the village and the population invited to participate. Village residents willing to participate were informed of the examinations and procedures they would undergo and the rationale of keeping part of their biological samples for future research investigations was explained. Those who accepted to participate signed a consent form and were interviewed by trained staff. A sample of faeces was collected in a small plastic container and stored in an ice box for about 2–3 days before being transferred to the laboratory for examination.
Faecal samples were processed by the formalin ethyl acetate concentration technique (Elkins et al. 1990). When of OV eggs were found, the intensity of eggs per gramme (EPG) of faeces was determined by using Stoll's egg count.
During the phase of recruitment to the study cohort, villages in the province were selected for participation and the eligible population (35 years and older) recruited during 2–3 weeks of fieldwork. All 20 districts were included. Initially, one subdistrict was selected from each at random, and one of the villages within it chosen, based on the recommendation of the local health personnel (to maximize compliance). Later, for some districts, screening took place in all subdistricts; or, in other districts, all of the villages in the chosen subdistrict were screened. For some districts, more than one subdistrict was sampled. As a result, the sampling fraction by district was quite variable, and the time period during which the populations of different districts were tested was quite different.
During study recruitment, the head of the village was contacted and the aim of the intervention explained. Lists of the resident population were obtained and files of eligible people prepared. The study team visited the village, with a mobile unit equipped with an ultrasound machine. The unit was then installed in the village and the population invited to participate. Village residents willing to participate were informed of the examinations and procedures they would undergo and the rationale of keeping part of their biological samples for future research investigations was explained. Those who accepted to participate signed a consent form and were interviewed by trained staff. A sample of faeces was collected in a small plastic container and stored in an ice box for about 2–3 days before being transferred to the laboratory for examination.
Faecal samples were processed by the formalin ethyl acetate concentration technique (Elkins et al. 1990). When of OV eggs were found, the intensity of eggs per gramme (EPG) of faeces was determined by using Stoll's egg count.
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