Use of Larvivorous Fish in Biological and Environmental Control of Disease Vectors - Biological and Environmental Control of Disease Vectors - page 31

than 50%, more than 90% of which was
identifi ed as P . falciparum . The post-intervention
phase showed a sharp steady decline in the total
number of malaria cases ( P . vivax : 105 to 0; P .
falciparum 1332 to 0). Monitoring of ento-
mological results revealed a signifi cant decline
in man-hour density of overall Anopheles species
(32.17 to 0.0) and An . culicifacies (25.83 to 0.0).
In Goa, India, both the density of An . stephensi
and three measures of malaria incidence
(malaria cases, slide positivity rate and annual
parasite index) decreased signifi cantly after
breeding sites were treated with Bti and the
indigenous fi sh Aplocheilus blocki compared to
untreated nearby villages (Kumar et al ., 1998).

Srinivaspura) in Tumkur District from March to
May 2006 for Poecilia and one village (Balmanda)
in Kolar District from July to October 2006 for
Gambusia . A survey on knowledge, attitude and
practice (KAP) on Chikungunya was initially
conducted and IEC campaigns were performed
before and after fi sh release in Domatmari (IEC
alone, followed by IEC + Poecilia ) and Balmanda
(IEC + Gambusia ). In Srinivaspura, IEC was not
conducted. Larval surveys were conducted at
the baseline followed by 1-week and 1-month
post-intervention periods. Indoor cement tanks
were the most preferred St . aegypti breeding
habitats (86.9%). After the introduction of fi sh,
Chikungunya cases were reduced by 99.9% in
Domatmari, 65.5% in Srinivaspura and 68.5%
in Balmanda. Poecilia exhibited greater survival
rates than Gambusia (86.0 versus 16.0%) in
cement tanks. Neither IEC nor Poecilia alone was
ef ective against Stegomyia , so it was concluded
that the combination of Poecilia + IEC was an
ef ective intervention strategy. Therefore, IEC
that focuses on proper water storage practices
combined with Poecilia introductions and vector
sanitation involving the local administration
and community is suggested as the best strategy
for Stegomyia control in India (Ghosh et al .,
2011).

Dengue
A community-based study on the distribution of
the larvivorous fi sh species P . reticulata in water
storage containers for dengue control was
undertaken in 14 villages and approximately
1000 households in Cambodia (Seng et al .,
2008). Community volunteers reared guppies
and distributed them to water jars and tanks in
households. One year after introduction, 56.9%
of the containers still contained guppies, and
there was a 79.0% reduction in Stegomyia
infestation in the intervention community
compared to the control. Lower population
indices of Stegomyia larvae, as measured by
using both the house index (percentage of
houses that have larvae of St . aegypti in at least
some containers) and the Breteau index (total
number of containers with larvae of St . aegypti
per 100 houses) were achieved by this inter-
vention and correlated with lower dengue risk
(WHO, 2003a).

3.3.3 Habitat modifi cation as a
part of environmental control of
vector-borne diseases by
larvivorous fi sh

A few species of the genus Mansonia , vectors of
Brugian fi lariasis, breed in habitats containing
water weeds such as Pistia , Eichhornia and
Pontederia (Chandra et al ., 2006). Immature
stages of Mansonia plug their siphon trumpets
into the air-pockets of water weeds to respire.
Two species of weedivorous as well as larvivorous
fi shes ( Osphrenomus gourami and Cteno-
pharyngodon idella ) feed on water weeds and
modify perennial weed-infested habitats into
weed-free ones. This stops Mansonia mosquitoes
breeding, thereby reducing transmission of
Brugian fi lariasis (Mitchell, 1974; Jayasree et al .,
1989; Lancar and Krake, 2002) (see also Lorenz
et al ., Chapter 4, this volume).

Chikungunya
In 2006, severe outbreaks of St . aegypti , vectors
of Chikungunya in India, occurred in villages in
Karnataka, south India. The ef ectiveness of
combined information, education and com-
munication (IEC) campaigns using two potential
poeciliid larvivorous fi sh species ( P . reticulata
and G . ai nis ) in indoor cement tanks for
Stegomyia larval control was evaluated. Trials
were conducted in two villages (Domatmari and