We selected the following variables a priori to investigate possible effect modification in the relationship between precipitation shocks and reported symptoms of diarrheal disease: household’s source of drinking water, type of sanitation facility, treatment of water before drinking, child stool disposal practices, feeding practices, and rotavirus immunization status. A short description of each variable is provided below; more detailed information is included in SI Appendix, Table S2 .
Drinking water sources and sanitation facilities are classified based on WHO/UNICEF guidelines (53 ). We distinguish between water that is piped into the dwelling and other sources of drinking water. Sanitation facilities are also classified as either “improved” or “unimproved.” “Improved” facilities include flush toilet, piped sewer system, septic tanks, and other safe facilities which do not contaminate the living environment. “Unimproved” facilities include pit latrine, bucket toilet, other unsafe facilities, or the general lack of sanitation facilities on the premise.
The water treatment method is classified as “adequate” if it makes the water safe for consumption and “inadequate” otherwise. Adequate treatment methods include boiling, adding bleach, or chlorine and solar disinfection, among other methods (SI Appendix, Table S2 ).
Child stool disposal practices, which are an important but often overlooked aspect of sanitary behavior in poor settings (54 (link)), are classified as “safe” or “unsafe.” Unsafe disposal can lead to contamination of the living environment (15 (link)). In fact, exposure to children’s stool is considered riskier than adult feces due to high concentration of pathogens (54 (link)). Despite that, children’s stool is often improperly disposed of due to the false assumptions that is it innocuous (16 (link)). To be considered safe, the stool must be either disposed of in a toilet/latrine or buried.
Although some DHS surveys provide data on additional hygiene practices such as handwashing, water treatment and stool disposal were the only variable concerning hygiene behavior available in most surveys included in the analysis. Moreover, safe stool disposal has been identified as a primary barrier to the transmission of pathogens and may be more important than handwashing which constitutes a secondary barrier (14 (link)).
We additionally group the WaSH variables to explore their combined effect. In particular, drinking water source is grouped with water treatment method, whereas type of sanitation facility is grouped with stool disposal practices.
Feeding practices are assessed based on the WHO/UNICEF guidelines for infants and young children (55 ). Under 6 mo of age, it is recommended that children are exclusively breastfed. Beyond 6 mo of age, the introduction of complementary foods is essential for the healthy development of children (56 (link)). We use information about children’s dietary diversity and meal frequency collected for children between 6 and 23 mo of age. Detailed description of this variable is available inSI Appendix, Table S2 . We exclude children under 6 mo of age from the analysis since the information provided in DHS is not sufficient to infer their meal frequency. Additionally, formula feeding may be adequate for this age group if clean water is available; however, we do not have a reliable indicator for the quality of water used to prepare the formula.
Finally, we extract information about children’s rotavirus immunization status. In DHS, vaccination status, including number of doses and age at vaccination, is collected from vaccination cards. If such cards are not presented, mother’s recall is used instead. Depending on the national immunization programs, children are usually administered two or three doses of the vaccine. We classify children as immunized if they completed the full immunization schedule. Information about rotavirus immunization was only collected in DHS round VII and for a limited number of countries. For this reason, our analysis concerning rotavirus immunization was restricted to 86,413 observations from 19 surveys.
Drinking water sources and sanitation facilities are classified based on WHO/UNICEF guidelines (53 ). We distinguish between water that is piped into the dwelling and other sources of drinking water. Sanitation facilities are also classified as either “improved” or “unimproved.” “Improved” facilities include flush toilet, piped sewer system, septic tanks, and other safe facilities which do not contaminate the living environment. “Unimproved” facilities include pit latrine, bucket toilet, other unsafe facilities, or the general lack of sanitation facilities on the premise.
The water treatment method is classified as “adequate” if it makes the water safe for consumption and “inadequate” otherwise. Adequate treatment methods include boiling, adding bleach, or chlorine and solar disinfection, among other methods (
Child stool disposal practices, which are an important but often overlooked aspect of sanitary behavior in poor settings (54 (link)), are classified as “safe” or “unsafe.” Unsafe disposal can lead to contamination of the living environment (15 (link)). In fact, exposure to children’s stool is considered riskier than adult feces due to high concentration of pathogens (54 (link)). Despite that, children’s stool is often improperly disposed of due to the false assumptions that is it innocuous (16 (link)). To be considered safe, the stool must be either disposed of in a toilet/latrine or buried.
Although some DHS surveys provide data on additional hygiene practices such as handwashing, water treatment and stool disposal were the only variable concerning hygiene behavior available in most surveys included in the analysis. Moreover, safe stool disposal has been identified as a primary barrier to the transmission of pathogens and may be more important than handwashing which constitutes a secondary barrier (14 (link)).
We additionally group the WaSH variables to explore their combined effect. In particular, drinking water source is grouped with water treatment method, whereas type of sanitation facility is grouped with stool disposal practices.
Feeding practices are assessed based on the WHO/UNICEF guidelines for infants and young children (55 ). Under 6 mo of age, it is recommended that children are exclusively breastfed. Beyond 6 mo of age, the introduction of complementary foods is essential for the healthy development of children (56 (link)). We use information about children’s dietary diversity and meal frequency collected for children between 6 and 23 mo of age. Detailed description of this variable is available in
Finally, we extract information about children’s rotavirus immunization status. In DHS, vaccination status, including number of doses and age at vaccination, is collected from vaccination cards. If such cards are not presented, mother’s recall is used instead. Depending on the national immunization programs, children are usually administered two or three doses of the vaccine. We classify children as immunized if they completed the full immunization schedule. Information about rotavirus immunization was only collected in DHS round VII and for a limited number of countries. For this reason, our analysis concerning rotavirus immunization was restricted to 86,413 observations from 19 surveys.
