Volume 95, Issue 5
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645



Herd immunity arises when a communicable disease is less able to propagate because a substantial portion of the population is immune. Nonimmunizing interventions, such as insecticide-treated bednets and deworming drugs, have shown similar herd-protective effects. Less is known about the herd protection from drinking water, sanitation, and hand hygiene (WASH) interventions. We first constructed a transmission model to illustrate mechanisms through which different WASH interventions may provide herd protection. We then conducted an extensive review of the literature to assess the validity of the model results and identify current gaps in research. The model suggests that herd protection accounts for a substantial portion of the total protection provided by WASH interventions. However, both the literature and the model suggest that sanitation interventions in particular are the most likely to provide herd protection, since they reduce environmental contamination. Many studies fail to account for these indirect effects and thus underestimate the total impact an intervention may have. Although cluster-randomized trials of WASH interventions have reported the total or overall efficacy of WASH interventions, they have not quantified the role of herd protection. Just as it does in immunization policy, understanding the role of herd protection from WASH interventions can help inform coverage targets and strategies that indirectly protect those that are unable to be reached by WASH campaigns. Toward this end, studies are needed to confirm the differential role that herd protection plays across the WASH interventions suggested by our transmission model.


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  1. Bartram J, Cairncross S, , 2010. Hygiene, sanitation, and water: forgotten foundations of health. PLoS Med 7: e1000367.[Crossref] [Google Scholar]
  2. Halloran ME, Struchiner CJ, , 1991. Study designs for dependent happenings. Epidemiology 2: 331338.[Crossref] [Google Scholar]
  3. Hayes RJ, Alexander ND, Bennett S, Cousens SN, , 2000. Design and analysis issues in cluster-randomized trials of interventions against infectious diseases. Stat Methods Med Res 9: 95116.[Crossref] [Google Scholar]
  4. Ali M, Emch M, von Seidlein L, Yunus M, Sack DA, Rao M, Holmgren J, Clemens JD, , 2005. Herd immunity conferred by killed oral cholera vaccines in Bangladesh: a reanalysis. Lancet 366: 4449.[Crossref] [Google Scholar]
  5. Musher DM, , 2006. Pneumococcal vaccine: direct and indirect (“herd”) effects. N Engl J Med 354: 15221524.[Crossref] [Google Scholar]
  6. Hawley WA, Phillips-Howard PA, ter Kuile FO, Terlouw DJ, Vulule JM, Ombok M, Nahlen BL, Gimnig JE, Kariuki SK, Kolczak MS, Hightower AW, , 2003. Community-wide effects of permethrin-treated bed nets on child mortality and malaria morbidity in western Kenya. Am J Trop Med Hyg 68: 121127. [Google Scholar]
  7. Hii JL, Smith T, Vounatsou P, Alexander N, Mai A, Ibam E, Alpers MP, , 2001. Area effects of bednet use in a malaria-endemic area in Papua New Guinea. Trans R Soc Trop Med Hyg 95: 713.[Crossref] [Google Scholar]
  8. Howard SC, Omumbo J, Nevill C, Some ES, Donnelly CA, Snow RW, , 2000. Evidence for a mass community effect of insecticide-treated bednets on the incidence of malaria on the Kenyan coast. Trans R Soc Trop Med Hyg 94: 357360.[Crossref] [Google Scholar]
  9. Miguel E, Kremer M, , 2004. Worms: identifying impacts on education and health in the presence of treatment externalities. Econometrica 72: 159217.[Crossref] [Google Scholar]
  10. Bundy DA, Wong MS, Lewis LL, Horton J, , 1990. Control of geohelminths by delivery of targeted chemotherapy through schools. Trans R Soc Trop Med Hyg 84: 115120.[Crossref] [Google Scholar]
  11. Attia S, Egger M, Muller M, Zwahlen M, Low N, , 2009. Sexual transmission of HIV according to viral load and antiretroviral therapy: systematic review and meta-analysis. AIDS 23: 13971404.[Crossref] [Google Scholar]
  12. Granich RM, Gilks CF, Dye C, De Cock KM, Williams BG, , 2009. Universal voluntary HIV testing with immediate antiretroviral therapy as a strategy for elimination of HIV transmission: a mathematical model. Lancet 373: 4857.[Crossref] [Google Scholar]
  13. Chidambaram JD, Melese M, Alemayehu W, Yi E, Prabriputaloong T, Lee DC, Cevallos V, Zhou Z, Whitcher JP, Gaynor BD, Lietman TM, , 2004. Mass antibiotic treatment and community protection in trachoma control programs. Clin Infect Dis 39: e95e97.[Crossref] [Google Scholar]
  14. House JI, Ayele B, Porco TC, Zhou Z, Hong KC, Gebre T, Ray KJ, Keenan JD, Stoller NE, Whitcher JP, Gaynor BD, Emerson PM, Lietman TM, , 2009. Assessment of herd protection against trachoma due to repeated mass antibiotic distributions: a cluster-randomised trial. Lancet 373: 11111118.[Crossref] [Google Scholar]
  15. Barreto ML, Genser B, Strina A, Assis AMO, Rego RF, Teles CA, Prado MS, Matos SM, Santos DN, dos Santos LA, , 2007. Effect of city-wide sanitation programme on reduction in rate of childhood diarrhoea in northeast Brazil: assessment by two cohort studies. Lancet 370: 16221628.[Crossref] [Google Scholar]
  16. Fuller JA, Villamor E, Cevallos W, Trostle J, Eisenberg JNS, , 2016. I get height with a little help from my friends: herd protection from sanitation on child growth in rural Ecuador. Int J Epidemiol 45: 460469.[Crossref] [Google Scholar]
  17. Van de Poel E, O'donnell O, Van Doorslaer E, , 2009. What explains the rural-urban gap in infant mortality: household or community characteristics? Demography 46: 827850.[Crossref] [Google Scholar]
  18. Alderman H, Hentschel J, Sabates R, , 2003. With the help of one's neighbors: externalities in the production of nutrition in Peru. Soc Sci Med 56: 20192031.[Crossref] [Google Scholar]
  19. Eisenberg JN, Scott JC, Porco T, , 2007. Integrating disease control strategies: balancing water sanitation and hygiene interventions to reduce diarrheal disease burden. Am J Public Health 97: 846852.[Crossref] [Google Scholar]
  20. Li S, Eisenberg JN, Spicknall IH, Koopman JS, , 2009. Dynamics and control of infections transmitted from person to person through the environment. Am J Epidemiol 170: 257265.[Crossref] [Google Scholar]
  21. R Development Core Team, 2013. R: A Language and Environment for Statistical Computing. Vienna, Austria: R Foundation for Statistical Computing. [Google Scholar]
  22. Aiello AE, Coulborn RM, Perez V, Larson EL, , 2008. Effect of hand hygiene on infectious disease risk in the community setting: a meta-analysis. Am J Public Health 98: 13721381.[Crossref] [Google Scholar]
  23. Arnold BF, Colford JM, Jr, 2007. Treating water with chlorine at point-of-use to improve water quality and reduce child diarrhea in developing countries: a systematic review and meta-analysis. Am J Trop Med Hyg 76: 354364. [Google Scholar]
  24. Cairncross S, Hunt C, Boisson S, Bostoen K, Curtis V, Fung IC, Schmidt WP, , 2010. Water, sanitation and hygiene for the prevention of diarrhoea. Int J Epidemiol 39 (Suppl 1): i193i205.[Crossref] [Google Scholar]
  25. Clasen T, Schmidt WP, Rabie T, Roberts I, Cairncross S, , 2007. Interventions to improve water quality for preventing diarrhoea: systematic review and meta-analysis. BMJ 334: 782.[Crossref] [Google Scholar]
  26. Curtis V, Cairncross S, , 2003. Effect of washing hands with soap on diarrhoea risk in the community: a systematic review. Lancet Infect Dis 3: 275281.[Crossref] [Google Scholar]
  27. Esrey SA, Potash JB, Roberts L, Shiff C, , 1991. Effects of improved water supply and sanitation on ascariasis, diarrhoea, dracunculiasis, hookworm infection, schistosomiasis, and trachoma. Bull World Health Organ 69: 609621. [Google Scholar]
  28. Fewtrell L, Kaufmann RB, Kay D, Enanoria W, Haller L, Colford JM, Jr, 2005. Water, sanitation, and hygiene interventions to reduce diarrhoea in less developed countries: a systematic review and meta-analysis. Lancet Infect Dis 5: 4252.[Crossref] [Google Scholar]
  29. Gundry S, Wright J, Conroy R, , 2004. A systematic review of the health outcomes related to household water quality in developing countries. J Water Health 2: 113. [Google Scholar]
  30. Hunter PR, , 2009. Household water treatment in developing countries: comparing different intervention types using meta-regression. Environ Sci Technol 43: 89918997.[Crossref] [Google Scholar]
  31. Waddington H, Snilstveit B, White H, Fewtrell L, , 2009. Water, Sanitation and Hygiene Interventions to Combat Childhood Diarrhoea in Developing Countries. New Delhi, India: International Initiative for Impact Evaluation. [Google Scholar]
  32. Wolf J, Prüss-Ustün A, Cumming O, Bartram J, Bonjour S, Cairncross S, Clasen T, Colford JM, Curtis V, France J, , 2014. Systematic review: assessing the impact of drinking water and sanitation on diarrhoeal disease in low-and middle-income settings: systematic review and meta-regression. Trop Med Int Health 19: 928942.[Crossref] [Google Scholar]
  33. Adedini SA, Odimegwu C, Imasiku EN, Ononokpono DN, Ibisomi L, , 2015. Regional variations in infant and child mortality in Nigeria: a multilevel analysis. J Biosoc Sci 47: 165187.[Crossref] [Google Scholar]
  34. Sastry N, , 1996. Community characteristics, individual and household attributes, and child survival in Brazil. Demography 33: 211229.[Crossref] [Google Scholar]
  35. Adekanmbi VT, Kayode GA, Uthman OA, , 2013. Individual and contextual factors associated with childhood stunting in Nigeria: a multilevel analysis. Matern Child Nutr 9: 244259.[Crossref] [Google Scholar]
  36. Chikhungu LC, Madise NJ, Padmadas SS, , 2014. How important are community characteristics in influencing children's nutritional status? Evidence from Malawi population-based household and community surveys. Health Place 30: 187195.[Crossref] [Google Scholar]
  37. Kayode GA, Amoakoh-Coleman M, Agyepong IA, Ansah E, Grobbee DE, Klipstein-Grobusch K, , 2014. Contextual risk factors for low birth weight: a multilevel analysis. PLoS One 9: e109333.[Crossref] [Google Scholar]
  38. Fuller JA, Westphal JA, Kenney B, Eisenberg JN, , 2015. The joint effects of water and sanitation on diarrhoeal disease: a multicountry analysis of the Demographic and Health Surveys. Trop Med Int Health 20: 284292.[Crossref] [Google Scholar]
  39. Andres LA, Briceño B, Chase C, Echenique JA, , 2014. Sanitation and Externalities: Evidence from Early Childhood Health in Rural India. Washington, DC: World Bank.[Crossref] [Google Scholar]
  40. Root GP, , 2001. Sanitation, community environments, and childhood diarrhoea in rural Zimbabwe. J Health Popul Nutr 19: 7382. [Google Scholar]
  41. Santos CA, Strina A, Amorim LD, Genser B, Assis AM, Prado MS, Barreto ML, , 2012. Individual and contextual determinants of the duration of diarrhoeal episodes in preschool children: a longitudinal study in an urban setting. Epidemiol Infect 140: 689696.[Crossref] [Google Scholar]
  42. Barreto ML, Genser B, Strina A, Teixeira MG, Assis A, Rego RF, Teles CA, Prado MS, Matos S, Alcântara-Neves NM, , 2011. Impact of a city-wide sanitation programme in northeast Brazil on intestinal parasites infection in young children. Environ Health Perspect 118: 16371642.[Crossref] [Google Scholar]
  43. Geruso M, Spears D, , 2015. Neighborhood Sanitation and Infant Mortality. Working Paper 21184. Cambridge, MA: National Bureau of Economic Research.[Crossref] [Google Scholar]
  44. Bateman OM, Smith S, , 1991. A Comparison of the Health Effects of Water Supply and Sanitation in Urban and Rural Guatemala. The Demographic and Health Surveys World Conference, Volume 2, August 5–7, 1991, Columbia, MD. [Google Scholar]
  45. Buttenheim AM, , 2008. The sanitation environment in urban slums: implications for child health. Popul Environ 30: 2647.[Crossref] [Google Scholar]
  46. Luby SP, Halder AK, Huda T, Unicomb L, Johnston RB, , 2011. The effect of handwashing at recommended times with water alone and with soap on child diarrhea in rural Bangladesh: an observational study. PLoS Med 8: 798.[Crossref] [Google Scholar]
  47. Nunes JK, Woods C, Carter T, Raphael T, Morin MJ, Diallo D, Leboulleux D, Jain S, Loucq C, Kaslow DC, , 2014. Development of a transmission-blocking malaria vaccine: progress, challenges, and the path forward. Vaccine 32: 55315539.[Crossref] [Google Scholar]
  48. Delrieu I, Leboulleux D, Ivinson K, Gessner BD, Malaria Transmission Blocking Vaccine Technical Consultation Group; , 2015. Design of a phase III cluster randomized trial to assess the efficacy and safety of a malaria transmission blocking vaccine. Vaccine 33: 15181526.[Crossref] [Google Scholar]
  49. Mausezahl D, Christen A, Pacheco GD, Tellez FA, Iriarte M, Zapata ME, Cevallos M, Hattendorf J, Cattaneo MD, Arnold B, , 2009. Solar drinking water disinfection (SODIS) to reduce childhood diarrhoea in rural Bolivia: a cluster-randomized, controlled trial. PLoS Med 6: 882.[Crossref] [Google Scholar]
  50. McGuigan KG, Samaiyar P, du Preez M, Conroy RM, , 2011. High compliance randomized controlled field trial of solar disinfection of drinking water and its impact on childhood diarrhea in rural Cambodia. Environ Sci Technol 45: 78627867.[Crossref] [Google Scholar]
  51. Clasen T, Boisson S, Routray P, Torondel B, Bell M, Cumming O, Ensink J, Freeman M, Jenkins M, Odagiri M, , 2014. Effectiveness of a rural sanitation programme on diarrhoea, soil-transmitted helminth infection, and child malnutrition in Odisha, India: a cluster-randomised trial. Lancet Glob Health 2: e645e653.[Crossref] [Google Scholar]
  52. Patil SR, Arnold BF, Salvatore AL, Briceno B, Ganguly S, Colford JM, Jr Gertler PJ, , 2014. The effect of India's Total Sanitation Campaign on defecation behaviors and child health in rural Madhya Pradesh: a cluster randomized controlled trial. PLoS Med 11: e1001709.[Crossref] [Google Scholar]
  53. Luby SP, Agboatwalla M, Painter J, Altaf A, Billhimer WL, Hoekstra RM, , 2004. Effect of intensive handwashing promotion on childhood diarrhea in high-risk communities in Pakistan: a randomized controlled trial. JAMA 291: 25472554.[Crossref] [Google Scholar]
  54. Luby SP, Agboatwalla M, Feikin DR, Painter J, Billhimer W, Altaf A, Hoekstra RM, , 2005. Effect of handwashing on child health: a randomised controlled trial. Lancet 366: 225233.[Crossref] [Google Scholar]
  55. Enger KS, Nelson KL, Rose JB, Eisenberg JN, , 2013. The joint effects of efficacy and compliance: a study of household water treatment effectiveness against childhood diarrhea. Water Res 47: 11811190.[Crossref] [Google Scholar]
  56. Luby S, , 2014. Is targeting access to sanitation enough? Lancet Glob Health 2: e619e620.[Crossref] [Google Scholar]
  57. Emch M, Ali M, Root ED, Yunus M, , 2009. Spatial and environmental connectivity analysis in a cholera vaccine trial. Soc Sci Med 68: 631637.[Crossref] [Google Scholar]
  58. Eisenberg JN, Trostle J, Sorensen RJ, Shields KF, , 2012. Toward a systems approach to enteric pathogen transmission: from individual independence to community interdependence. Annu Rev Public Health 33: 239257.[Crossref] [Google Scholar]
  59. Barnard S, Routray P, Majorin F, Peletz R, Boisson S, Sinha A, Clasen T, , 2013. Impact of Indian Total Sanitation Campaign on latrine coverage and use: a cross-sectional study in Orissa three years following programme implementation. PLoS One 8: e71438.[Crossref] [Google Scholar]

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Supplementary PDF

  • Received : 17 Sep 2015
  • Accepted : 20 Jul 2016
  • Published online : 02 Nov 2016

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