Soil-transmitted helminthic infection and its effect on nutritional status of adolescent schoolgirls of low socioeconomic status in Sri Lanka

aetiology ascariasis ascaridiose ascaris lumbricoides disease prevalence epidemiologia epidemiologie epidemiology estado nutricional estructura social etiologia etiologie haemoglobin helminthe helminths helmintos hemoglobina higiene host parasite relations hygiene infecciones por nematodos jeunesse juventud living conditions living standards nematode infections niveau de vie nivel de vida nutritional status retinol rural areas social structure structure sociale trichuriasis trichuris youth zonas rurales zone rurale