Chickens don't use toilets: Why managing animal feces helps children grow taller


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Chhor Sokunthea / World Bank

Those who have tried toilet training a pet dog or cat know that it is a difficult proposition. How about toilet training a flock of 30 chickens?

“Why would I want to?” Because in poor countries, chickens are everywhere, they are pooping wherever they want, and chicken feces is dangerous for young children.

How do we know this? In two papers released last year in the journals PLOS One and American Journal of Tropical Medicine & Hygiene, my coauthors and I investigated the emerging hypothesis that exposure to animal feces is a serious risk factor for infections and undernutrition in early childhood. Our work suggests that the predominant water, sanitation, and hygiene (WASH) focus on reducing exposure to human feces needs updating by including animal feces.

As far back as 1990, a study in urban Peru found that toddlers directly ingested chicken excrement. In 2013, a study of young children in rural Zimbabwe found the same problem. That team hypothesized that this isn’t just a risk factor for diarrhea; it might be an important cause for stunting, through a more invisible, “sub-clinical” and chronic form of damage to the gut, with the not-so-catchy name of environmental enteric dysfunction, or EED. While nutritionists have long speculated that infection in general may be a major cause of undernutrition, many are now increasingly convinced that EED is a prime suspect.

In 2016 we set out to test the indirect linkage between exposure to animal feces and undernutrition. In our first study, we took advantage of a large household survey in Ethiopia to add questions on whether villagers kept animals inside their main dwelling overnight. We reasoned that keeping animals indoors would likely mean more animal feces in and around the house. We knew that many Ethiopians kept their animals close, but we underestimated just how close: fully half of Ethiopian households keep chickens and children in the same building at night, but goats, cows and donkeys also get to sleep indoors on a regular basis. However, it was only the practice of keeping chickens indoors (mostly due to fear of theft and predation) that was associated with slower child growth, consistent with the findings of the earlier studies in Peru and Zimbabwe, where exposure to poultry was the main risk.

Strikingly, a smaller but more biologically oriented study from Bangladesh— which used the presence of chickens as its eligibility criterion, but also included other animals—found a similar result with a similar indicator: keeping animals indoors overnight was associated with both child stunting and EED symptoms .

In our second paper, we took advantage of the Alive and Thrive surveys in Bangladesh, Ethiopia and Vietnam. Alive and Thrive researchers had the good sense to ask their surveyors to visually assess the hygiene standards of every household they visited, including whether animal and human feces were observed in the compound. As in the first study, we were surprised by the scale of exposure to animals and animal feces. Around 40 percent of households in all three countries had animal feces in their compounds, whereas the presence of human feces was rare. And as in the first study, this exposure to animal feces was associated with slower child growth, even after controlling for many other dimensions of water, sanitation, and hygiene (WASH).

These findings are only suggestive (we didn’t randomly distribute animal feces!) but they are potentially of huge import. WASH interventions haven’t prioritized reducing exposure to animal feces because human feces are thought to be a more important risk factor for diarrhea. As one influential review from 2000 put it:

Whilst animal feces in food or water is a matter of current concern in developed countries, they may be of less relative importance in areas where human feces are disposed of inadequately... Further study is required… In the meantime, human stools should be regarded as public enemy number one.

In 2017 there are several very good reasons to reassess this conclusion.

Rod Waddington  |  Konso Village, Ethiopia

First, there are a large number of free-roaming livestock in developing countries defecating in areas where children sit, play, crawl and explore. We used DHS surveys to assess livestock ownership across 42 developing countries: in most regions, over half of rural households own poultry, but so do significant numbers of urban households. In contrast, open defecation (by humans) is becoming increasingly rare: just 5 countries account for 75 percent of open defecation. This implies that in the majority of countries, exposure to animal feces is far more common than exposure to human feces .

Second, human feces may be a more important reservoir for diarrheal pathogens, but at least one study conjectures that animal feces could be a (relatively) more important reservoir for pathogens that cause EED and stunting. Indeed, a systematic review of WASH interventions have found them to have surprisingly little impact on nutrition... Perhaps because these interventions stopped short of addressing exposure to animal feces?

If animal stools really are such an important risk factor for undernutrition, the development community now needs to start thinking about to how combat this risk. Here are two recommendations:

Derek Headey is a Senior Research Fellow in IFPRI"s Poverty, Health, and Nutrition Division (PHND).


Derek Headey

Senior Research Fellow, International Food Policy Research Institute

Richard Middleton
February 08, 2017

Two possible approaches:
1. If you have, or are planning to have, alternating VIP latrines, you should have a good way of treating chicken feces, rendering them pathogen-free, and providing high-quality humus (quite apart from the health issues, raw chicken feces used as manure tend to “burn” crops). David Dalmat tried to get something like this going in Haiti in the very early days of TAG (nearly 40 years ago!), with humus being provided to a USAID-funded reforestry program, but the local obstacles proved insuperable.
2. At one time (again, nearly 40 years ago) the Bank was gung-ho about duckweed aquaculture: treating human wastes in ponds growing duckweed, which is then fed to tilapia (see Paul Skillicorn’s booklet published by the Bank). But duckweed is also excellent feed for chickens (see Paul’s other publications). Which poses the obvious question: why not try putting the chicken feces in the duckweed ponds, and feed the chickens on the resulting duckweed? One interesting thing about Paul’s extensive work in Bangladesh was that the system was managed by farmers, not by public health or other government workers - it was the farmers who knew whether the duckweed was healthy or not, and who had a financial stake in ensuring a quality product.

Ed Bourque Consulting
February 10, 2017

Excellent post.
This issue is an urban one to some extent, as well, as there is no shortage of livestock roaming around freely in some African cities.
I live in Accra and every day I wake up to the sound of roosters and walk by goats and chickens.

Amber Barnes
February 11, 2017

Yes yes yes!
Thank you so much for this fantastic post. I have been researching the impact of domestic animals on household water contamination and their presence and waste are significantly associated with drinking water contamination in the peri-urban households of our study areas, despite the source of the drinking water to be considered "improved". Current WASH interventions and messages are not complete without the inclusion of domestic animal waste as a risk factor for contamination, enteric disease, and undernutrition. We must be sharing best practices for safe animal husbandry and contact in the urban and peri-urban setting where there is a high rate of cohabitation at night, animal waste deposited in community spaces and shared water sources, and the free roaming of animals due to a lack of land ownership or grass for pasture. One thing that I would like to note from my own research is that when looking at this human-animal interface, especially in peri-urban settings where I am familiar, the aspect of domestic animal ownership v. presence is quite different. Focusing WASH interventions with animal waste messages only to houses that report animal ownership will exclude a large amount of households that are at risk for animal waste exposure. We found that only 34% of our households said they owned an animal yet our observational data found that over 75% of these same households had domestic animals and/or domestic animal waste in their household compound. This means that the animals are moving into shared spaces and the entire community would benefit for messaging on safe disposal and handling of animal waste. Therefore I support the inclusion of animal waste management practices in household WASH interventions and educational programs. Thanks again for this post!

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Dawit Tadesse
February 21, 2017

Interesting article, thanks for sharing! the question now is how will WASH react to this.