Growth and Sanitation:
What can we learn from chickens?
Photo: Unsanitary living conditions cause illnesses that threaten children's
health and growth. New research now suggests that growth is harmed in unhygienic
surroundings even before acute infection occurs. In Egypt, a girl amid mounds
of garbage and animal waste.
Poultry farmers have known for some time that a chicken living in a dirty
environment is a chicken that grows poorly. Even if it is not overtly sick
all the time, it gains little weight.
Is there a message here about the growth of children? Because growth,
like other nutrition outcomes, is deter mined most immediately by diet and
illness status, the answer, at least in part, may be yes. Infectious illness
- which spreads more easily in unsanitary conditions - leads to poorer dietary
intake and poor use of the nutrients ingested. This, in turn, leads to lower
resistance to infection, and so on, in a vicious diet-infection cycle (Fig.
Now studies suggest that an unsanitary environment may have effects beyond
those associated with particular bouts of illness. Research ers believe
that children living in such conditions may suffer from a fairly constant,
low-level challenge to their immune systems that impairs their growth, as
has been shown in domestic fowl. Dr. Noel Solomons of the Centre for Studies
of Sensory Impairment, Aging and Metabolism and colleagues suggest that
along with classifying children as healthy (having no clinical illness)
and acutely infected (with signs of illness readily detectable), there is
also a category of "inapparently infected." Children who are inapparently
infected have no signs of clinical illness but do have abnormal levels of
some immunological indicators. Such inapparent infections and the chronic
low-level stimulation of the immune system associated with life in unsanitary
conditions may mean that nutrients go to support the body's immune response
rather than growth.
Poverty occurs in both South Asia and sub-Saharan Africa, but rates of
malnutrition, especially stunting, are much higher in South Asia. A number
of hypotheses have been advanced to explain this difference, and one is
that it is due to poorer sanitation and hygiene practices, the much greater
population density and degree of overcrowding in South Asia.
Certainly, the dangers posed by poor access to potable water are well
known. A recent review of data collected by the Dem o graphic and Health
Surveys, a USAID-supported project, indicates that health and nutrition
benefits from improved sanitation, especially improved ex creta disposal,
may be even greater than those associated with better access to safe water
A group led by Dr. Reynaldo Martorell of Emory University (US) has designed
a study to shed light on the relationship between sanitation and growth
stunting. This study would follow 800 children in two locations in South
Asia and 800 more in two locations in sub-Saharan Africa from the time their
mothers become pregnant to when they are two years old and would collect
a wide range of informa tion on sanitation, hygiene practices and other
aspects of the house hold environment. The children's growth would be meas
ured frequently along with indicators of feeding practices, diet quality,
illness and many other factors. UNICEF is helping to secure funds for this
Establishing a link between sanitation conditions and child growth in
a cause-and-effect way will go a long way to clarifying priorities for action
in this area. Such a link will also reveal just how useful the 'dirty chicken'
model is for understanding stunted growth among children.