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Spotlight 
  
April 2011 
Issue 6 
 
 
Introduction 
Malaria kills almost one million people worldwide every 
year. The disease is transmittedto humans by the bites 
of infected female Anopheles mosquitoes. Global efforts 
to  tackle  malaria  have  gained  unprecedented 
momentum aftera paradigm shift from malaria control 
to  malaria  eradication  following  the  ‘Gates  Malaria 
Forum’  held  in  Seattle  in  October  2007.  However,  in 
order  to  move  towards  the  ambitious  goal  of 
eliminating and eventually eradicating malaria, existing 
tools must be improved and new tools developed. Such 
tools need to be cost-effective, scalable, and compatible 
with prevailing health and social systems.  
 
The most important and widely-applied malaria control 
tools  available  today  comprise  artemisinin-based 
combination  therapies  for  treatment,  intermittent 
preventive  treatment  in  pregnancy  and  infants,  rapid 
and reliable diagnosis of malaria, and vector control by 
insecticide-treated  bednets  as  well  as  indoor  residual 
spraying. Complementary vector control measures that 
can  play  an  important  role  in  specific  settings  are 
environmental  management  (reduction  of  standing 
water bodies, for example by drainage) and larviciding 
(application  of  biological  or  synthetic  insecticides  in 
standing water bodies in order to kill mosquito larvae). 
 
Anopheles  mosquitoes  generally  breed  in  temporary 
sun-lit  small  ponds,  pools  and  puddles,  and  in  more 
permanent  habitats  such  as  marshes.  Anopheles 
mosquitoes prefer fresh water habitats, although they 
can also breed in polluted or saline waters. Examples for 
important breeding sites are shallow open sun-lit pools 
such  as  borrow  pits,  drains,  car  tracks,  hoofprints 
around  ponds  and  water  holes,  and  pools  left  as 
overflowing rivers and streams recede, and rainwater 
collecting in natural depressions. 
 
Larviciding can be a useful complementary strategy to 
the main malaria control tools (Castro et al., 2004; Chaki 
et  al.,  2009;  Fillinger  et  al.,  2008;  Geissbühler  et  al., 
2009),  particularly  in  urban  areas,  because  breeding 
habitats are usually fewer compared to rural areas and 
can be accessed. 
 
 
Anopheles mosquito breeding site in Dar es Salaam 
Community-based 
larviciding of mosquitoes 
contributes to malaria 
reduction 
Authors 
This paper was written by Stefan Dongus, Nicodem Govella, 
Prosper  Chaki,  Silas  Majambere,  Khadija  Kannady,  Tanya 
Russell and Gerry Killeen. Khadija Kannady is the Programme 
Manager  of  the  Dar  es  Salaam  Urban  Malaria  Control 
Programme.  All  other  authors  are  IHI  researchers  and 
affiliated to the Liverpool School of Tropical Medicine (UK).   
 
  
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Controlling mosquito larvae in Dar es 
Salaam 
The Dar es Salaam Urban Malaria Control Programme 
(UMCP) was been initiated by the Dar es Salaam City 
Council  in  collaboration  with  Ifakara  Health  Institute 
and a consortium of overseas partner institutions as a 
pilot  program  to  develop  sustainable  and 
affordablesystems for larval control as part of routine 
municipal services (Castro et al., 2004; Mukabana et al., 
2006).  Specifically,  the  UMCP  implements  the  regular 
application of biological larvicides through community-
based  but  vertically  manageddelivery  systems.  The 
current phase of the UMCP was launched in March 2004 
(Fillinger et al., 2008; Geissbühler et al., 2009). 
 
 
 
 
Application of microbial larvicide granules (Bacillus thuringiensis 
var.israelensis) by UMCP field worker 
The  UMCP  is  fully  integrated  into  the  existing  local 
administrative system of the Dar es Salaam City Council 
with  the  endorsement  of  the  Ministry  of  Health. 
Itoperates on all five administrative levels of the city: 
the city council, municipalities, wards, neighbourhoods, 
and more than 3,000 “ten-cell-units” (TCUs). The main 
tasks on the four upper levels are project management 
and  supervision,  whereas  the  actual  larval  control  is 
organized and implemented at the level of the smallest 
administrative  units,  the  TCUs.  The  UMCP  aims  at 
larviciding all breeding sites of malaria vectors in the 
programme’s intervention area. 
 
Intervention area of Dar es Salaam Urban Malaria Control 
Programme (2010) 
During the first year of the UMCP, new larval and adult 
mosquito  surveillance  systems  were  set  up  using 
practical procedures that rely on minimal technology. 
Staff  were  recruited  and  trained,  and  management 
systems were designed. After one year of baseline data 
collection,  operational  larviciding  with  Bacillus 
thuringiensis var. israelensis commenced in March 2006 
in three wards. A year later, the intervention area was 
expanded to nine wards.  
 
Since 2008, 15 urban wards of Dar es Salaam have been 
included  in  the  UMCP  larviciding  scheme,  covering  a 
population of approximately 612,000 residents and an 
area of 56 km
2. Responsibility for larviciding has been 
delegated  to  modestly-paid  communitymembers, 
known  as  Community-Owned  Resource  Persons 
(CORPs).  In  2009,  a  new  mobile-phone  based 
surveillance system was introduced which replaced the  
 
  
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former  (and  slower)  paper-based  system.  The  new 
systemallows  programme  managers  to  access 
information and optimize control strategies in a manner 
that  is  timely  enough  to  account  for  the  short 
reproductive cycle (ca. 1 week) of Anopheles gambiae 
mosquitoes, the primary malaria vectors. 
 
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Adult or immature sampling – laboratory or field populations
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PDAs
Web-based server
Database
Software
Mean biting rate of Anophelines (Dar esSalaam)
Report generation
Paper forms Mobile phones
 
Mobile-phone-based surveillance system 
A participatory mapping and monitoring approach has 
been  developed  and  introduced.  This  approach 
comprises  community-based  development  of  sketch 
maps of the target areas, andverification ofthe sketch 
maps using laminated aerial photographs in the field, 
which  are  thendigitized  and  analyzed  using 
Geographical Information Systems (GIS). This mapping 
approach has enabled gap-free coverage of intervention 
areas  with  mosquito  larval  control,  and  more  equal 
distribution of the workload of field staff (Dongus et al. 
2007).  
 
Participatory mapping: A - Sketch maps, B – Corresponding aerial 
photograph, C –laminated field map for digitization, D –Problem 
solving with programme management team 
Reduction of malaria infection & risk 
 
Reduction of malaria infection prevalence in children under 5 years 
of age and annual EIR (number of infective mosquito bites per 
person per year) during expansion of larviciding 
There  is  a  clear  downward  trend  in  malaria  infection 
prevalence in people, and their risk of exposure based 
on measured mosquito densities and infection rates in 
Dar es Salaam between 2005 and 2008. This is partly 
due  to  larviciding,  which  started  in  2006.  However, 
other  malaria  control  interventions  (such  as  use  of 
insecticide-treated bednets, introduction of artemisinin-
based combination therapies and screening of houses 
by  self-initiative)  have  contributed  to  the  observed 
reduction in malaria infection prevalence. 
 
The encouraging results in Dar es Salaam are paralleled 
by similarfindingsfromexperimental programmes in the 
highlands of Kenya (Fillinger 2009) and Eritrea (Shililu 
2007), and historical successes in the Zambian copper  
 
  
4 
 
belt and parts of Brazil and Egypt (Killeen 2002, 2003, 
Utzinger 2001, 2002).  
Larval control may be most useful for malaria control in 
areas  that  have  limited,  focal  distribution  of  surface 
water  (because  of  topographic  relief,  aridity  or 
urbanization),  high  human  populations  density,  and 
strong  governance  and  institutional  capacity  (Killeen 
2002, Killeen 2006). 
Challenges and prospects 
Complementary  intervention:  Larviciding  should  be 
seen as a complementary vector control tool in addition 
to  insecticide-treated  bednets  and  indoor  residual 
spraying. 
 
Access to breeding sites: While many breeding sites in 
urban areas are easy to access, some residents don’t 
allow  larviciding  teams  to  enter  their  compounds, 
leaving some mosquito breeding sites left untreated. 
 
Community  perception:  95%  of  mosquitoes  found  in 
Dar es Salaam are not Anopheles mosquitoes but still 
cause major nuisance. To sustain community trust in the 
effectiveness of the intervention, larviciding should aim 
to reduce the numbers of all mosquitoes. 
Short  treatment  intervals:  The  primary  malaria-
transmitting  mosquitoes  develop  from  egg  to  adult 
within a week or less. Because the currently-available 
larvicides only remain effective for around seven days, 
weekly re-treatment of breeding habitats is required.  
 
Quality  assurance:  Larviciding  teams  need  close 
supervision in order to sustain optimal performance. 
 
Monitoring:  High-resolution,  fine  scale  spatial  and 
temporal  monitoring  of  adult  mosquito  density  is 
needed in order to detect coverage gaps. 
 
Sustainability:  In  2010,  the  Government  of  Tanzania 
took  over  the  funding  of  the  programme  from 
international  donors.  Prior  to  handover,  changes  in 
administrative structure and field procedures achieved 
a halving of implementation cost – from less than $1.00 
to  less  than  $0.50  per  person  protected  per  year 
(Worrall 2007). 
Measuring  relative  impact:  In  this  study  area,  many 
different  malaria  control  interventions  have  been 
implemented  concurrently.  This  makes  it  difficult  to 
isolate the impact contribution of individual strategies. 
 
Acknowledgements 
We would like to thank the community members of the study areas in Dar es 
Salaam and all members of the Urban Malaria Control Programme involved 
in the implementation of this study. The Programme was funded by the Bill 
and Melinda Gates Foundation; the United States Agency for International 
Development through its Environmental Health Project, its Dar es Salaam 
mission  and  the  United  States  President’s  Malaria  Initiative;  Valent 
BioSciences Corporation; the Swiss Tropical and Public Health Institute; the 
Wellcome Trust; and the Swiss National Centre of Competence in Research 
(NCCR)  North-South.  Thanks  to  Mbarwa  Kivuyo  and  Paul  Smithson  of  IHI 
Resource Centre for editing and laying out the final manuscript. 
The *pdf version can be downloaded from our website: www.ihi.or.tz 
 
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Web: www.ihi.or.tz;  E-mail address: info@ihi.or.tz  
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Integrated urban malaria control: a case study in Dar es Salaam, Tanzania.

Microbial larvicide application by a large-scale, communitybased program reduces malaria infection prevalence in urban Dar es Salaam, Tanzania.

Community-Based Larviciding of Mosquitoes Contributes to Malaria Reduction

http://ihi.eprints.org/1832/1/Spotlight_Nr_6%2D_Larviciding_of_mosquitoes.FINAL.pdf

Community-Based Larviciding of Mosquitoes Contributes to Malaria Reduction

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