Integrated Vector Management - Biological and Environmental Control of Disease Vectors - page 182

water found in latrines (Curtis and Hawkins,
1982). The species of mosquito mostly
associated with breeding in latrines is Cx .
quinquefasciatus (Irving-Bell et al ., 1987).
Expanded polystyrene (EPS) beads have been
used to prevent the emergence of mosquito
larvae from pit latrines. In Zanzibar, the
reduction in light trap catches due to EPS beads
was 98.3% (Maxwell et al ., 1990). In India, a
reduction of over 90% in Culex numbers was
obtained through using EPS beads in latrines
and larvivorous fi sh in wells (Sunish et al .,
2007). In urban Dar es Salaam, Tanzania, a
combination of using EPS beads (in latrines and
septic tanks) and pyriproxyfen (in blocked drains
and fl ooded land) reduced Culex populations by
76.7% and 46.2% in two contrasting areas of
the city: Mikocheni and Ilala, respectively
(Chavasse et al ., 1995). It is possible that EPS
beads could reduce fi lth fl ies, as well as
mosquitoes, emerging from pit latrines, and that
the construction of latrines will reduce popu-
lations of mosquitoes. Neither hypothesis has
been tested in the fi eld. Such interventions could
additionally impact on other vectors associated
with pit latrines, such as cockroaches and
calliphorid fl ies, and the diseases they transmit.
However, before advocating widespread
construction of latrines for the control of vector-
borne diseases, an important consideration is
that latrines need maintenance, and are only
truly ef ective at preventing disease if they are
used properly. Furthermore, signifi cant
reductions in diarrhoeal cases cannot occur if
the amount of breeding sites remains high, so
interventions involved in providing communities
with sanitation facilities must also ensure that
health education is made a priority (Pattanayak
et al ., 2009), and removal of livestock from
within villages is facilitated to reduce the risk of
the fl ies breeding in the vicinity of human
habitation (Emerson et al ., 2005). Allowing the
latrine and pit to fall into disrepair, or supplying
vent pipes without screens, provides an
opportunity for fl ies and mosquitoes to gain
access to breeding sites, rendering latrines
inef ective or even counter-ef ective as a method
of control (Curtis and Hawkins, 1982; Huttly et
al ., 1998).
The uptake of sanitation in large-scale
disease control programmes has been slow,

possibly due to a lack of compelling evidence
concerning its ef ectiveness and cost-
ef ectiveness (Waddinton et al ., 2009). In two
recent systematic reviews, examining the use of
sanitation to prevent diarrhoea, the authors
were unable to identify a single intervention
study, much less a randomized, controlled fi eld
trial, providing rigorous evidence on the
contribution of latrines to prevent diarrhoea
(Waddinton et al ., 2009; Clasen et al ., 2010).
Intervention studies were either not randomized
or used heterogeneous interventions and
methodologies, such as combining sanitation
with water or hygiene interventions, so it was
impossible to identify the contribution of
sanitation alone. Since then, one study has
demonstrated that latrine use is associated with
a reduction in diarrhoeal diseases (Semba et al .,
2011).
A collaborative randomized control study is
currently underway to evaluate the ef ects of
pour-fl ush latrines in 100 villages in Orissa
State, India. Researchers from several institutes
(London School of Hygiene & Tropical Medicine,
University of California-Davis, Emory University,
University of California, Xavier Management
Institute, and Loyola Hospital) are working in
partnership with WaterAid India and other local
NGOs, who will mobilize householders in target
villages to construct and use latrines in
accordance with the Government of India's
Total Sanitation Campaign. The aim of the study
is to develop an evidence-based sanitation
strategy for rural settings in India, and other
low-income countries, so that it achieves optimal
gains in public health, and is scalable,
sustainable, adequately funded and fully
endorsed by all stakeholders. To obtain the
necessary supporting evidence, 50 villages will
be kept as controls and 50 villages will be
provided with pour fl ush latrines. Clinical
outcomes related to diarrhoeal and helminth
diseases will be measured over a 3 year period,
and entomological outcomes will be monitored
for 2 years to quantify the ef ect of intervention
on populations of fi lth fl ies and mosquitoes,
such as Cx . quinquefasciatus . If the intervention
reduces disease transmission, it is hoped that
pour fl ush latrines will be advocated for use in
IVM programmes to control all diseases
transmitted by these vectors.