Ascariasis is a common infection in tropical and sub-tropical regions; 730 million to 804 million people are estimated to be infected worldwide.[3]Jourdan PM, Lamberton PHL, Fenwick A, et al. Soil-transmitted helminth infections. Lancet. 2018 Jan 20;391(10117):252-65.
http://www.ncbi.nlm.nih.gov/pubmed/28882382?tool=bestpractice.com
[4]Holland C, Sepidarkish M, Deslyper G, et al. Global prevalence of Ascaris infection in humans (2010-2021): a systematic review and meta-analysis. Infect Dis Poverty. 2022 Nov 18;11(1):113.
https://www.doi.org/10.1186/s40249-022-01038-z
http://www.ncbi.nlm.nih.gov/pubmed/36401308?tool=bestpractice.com
Within this global cohort, many are at risk of severe, sometimes life threatening complications.[3]Jourdan PM, Lamberton PHL, Fenwick A, et al. Soil-transmitted helminth infections. Lancet. 2018 Jan 20;391(10117):252-65.
http://www.ncbi.nlm.nih.gov/pubmed/28882382?tool=bestpractice.com
[10]de Silva NR, Chan MS, Bundy DA. Morbidity and mortality due to ascariasis: re-estimation and sensitivity analysis of global numbers at risk. Trop Med Int Health. 1997;2:519-28.
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[11]de Silva NR, Guyatt HL, Bundy DA. Morbidity and mortality due to Ascaris-induced intestinal obstruction. Trans R Soc Trop Med Hyg. 1997;91:31-36.
http://www.ncbi.nlm.nih.gov/pubmed/9093623?tool=bestpractice.com
In economically developed countries, ascariasis is primarily found in recent immigrants and children adopted from endemic countries.
Clay-containing soils favour the survival and dissemination of Ascaris eggs after rainfall. Eggs can also withstand freezing; therefore, the infection extends into northern temperate zones. Only cold, arid climates seem free of infection. Sanitation, socio-economic status, and access to health care are additional factors that influence the likelihood of infection within a given population.[12]World Health Organization. Soil-transmitted helminthiasis. Jan 2023 [internet publication].
https://www.who.int/news-room/fact-sheets/detail/soil-transmitted-helminth-infections
Heavy worm burdens are more common in children than adults.[1]Diemert DJ. Ascariasis. In: Guerrant RL, Walker DH, Weller PF, eds. Tropical infectious diseases: principles, pathogens and practice. 3rd ed. Edinburgh: W.B. Saunders; 2011:794-8.[13]Cooper PJ. Interactions between helminth parasites and allergy. Curr Opin Allergy Clin Immunol. 2009;9:29-37.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2680069
http://www.ncbi.nlm.nih.gov/pubmed/19106698?tool=bestpractice.com
In preschool-age children, exposure to subsistence agriculture has been associated with higher intensity infections.[14]Krause RJ, Koski KG, Pons E, et al. Ascaris and hookworm transmission in preschool children in rural Panama: role of subsistence agricultural activities. Parasitology. 2016;22:1-12.
http://www.ncbi.nlm.nih.gov/pubmed/27000494?tool=bestpractice.com