Introduction to the Agro-Ecology of Malaria
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Transcript of Introduction to the Agro-Ecology of Malaria
Review of Malaria, Environment, and
Agriculture Linkages
Financially supported by
http://www.ifpri.org/publication/malaria-and-agriculture
Health Background What is Malaria?
What role do mosquitos have?
Why does one place have malaria and not another? (Transmission)
Why are children more at risk than adults?
What can we do about malaria?
What is Malaria?“Malaria” is a parasite transmitted between humans by mosquito bites.
A malaria infection leads to:
Periods of Fever and periods of wellness (relapses)
Sweating, Chills, and Body-Aches
Headache, Nausea, and feeling hot
Fever of the Brain: Seizures and Death
Anemia or Jaundice
Infected person transmits parasite to mosquitos that bite them during the fever. (which then pass it to other humans).
4 Human Types of MalariaPlasmodium falciparum 90 % of human deaths
Deadly Brain Fever
Plasmodium vivax Less Deadly
Difficult to Treat
Fever every few months
Plasmodium ovale: Less Common
Less Deadly
Plasmodium malariae Less Common
Less Deadly
Other malaria types infect monkeys, antelope, birds, rodents, etc…
Malaria-Parasite Life-Cycle
Primary Health InterventionsBed-Nets: Insecticide Treated Nets (ITNs), and Long-Lasting Insecticide Nets (LLINs) to prevent mosquito bites and kill mosquitos
Indoor Residual Spraying (IRS) of Pesticides on the walls of homes to kill mosquitos
Drug-Treatments: Artemisinin Combination Therapies (ACTs) and Sulphadoxine-Pyrimethamine (SP) are two types of drugs commonly used to cure malaria infection
Environmental Management
“Environmental Management is where the environment is modified or manipulated to reduce malaria transmission by attacking local mosquitoes and requires an
understanding of the ecology of these species.”
WHO estimates 30 to 53 percent of the global malaria burden
(500,000 deaths) is attributable to modifiable environmental factors.
Examples of Environmental Management
Alternative Wet-Dry Irrigation
Clearing Canals of Vegetation
Sub-Surface Drainage of Wetlands
Leveling and Grading
Bacterial Larvicides
Larvivorous Fish - Other Predators
River modification to promote faster flows
Improved Livestock Housing
Adding Insect Screens to windows and doors.
Integrated Vector Management (IVM)
Evaluate the Efficacy of each
Intervention
Apply a full range of interventions
Implement Control Measures:
Bed-NetsDrug TreatmentIndoor Residual
SprayingEnvironmental Management
Measure the Impact on Mosquito
Populations and Human Infections
Test for Drug Resistance &
Pesticide Resistance
Identify Resistance Early ,
so it can be addressed.
Participatory Learning with the
Community: What is Working?
What is Not?
Change Strategies if You
Need to.
Test People for Malaria.
Measure the mosquito
population.
IVM is a way of managing
a malaria control program
Ross-MacDonald Model of Malaria Transmission
R0Basic transmission rate of the malaria parasite between humans and mosquitos
a number of bites of a human by a single mosquito per day (the “biting rate” of the local mosquitos)
b % of those bites that produce an infection in the human (how many mosquitos carry the infection)
c transmission efficiency from human to mosquito (how susceptible to infection is the human)
m number of mosquitoes per human host
Divided Byr how long the parasite is in the human’s blood-stream
(and transmitted to other mosquitos)
μ life-expectancy of mosquitoes (and how many people they can bite)
Intervention Effect on
R0
a2 b c m 1/r 1/μ
Biting Rate
% of mosquitos
infectedHuman
susceptibilityNumber of mosquitoes
duration of fever in humans
Mosquito Lifespan
Drug Treatment - - -
Indoor Residual
Spraying (IRS)- -
Bed-nets: ITNs and LLINs - -
Environmental Management - - -
How do Interventions reduce Malaria Transmission?
Conventional Interventions are Essential But Not Enough
It is not possible using the current set of interventions (Bed-Nets, Drugs, and Indoor Pesticide Spraying) to eliminate malaria from high transmission areas.
If R0 < 1 then transmission will tend towards zero over time and ultimately be interrupted. If R0 > 1 then malaria transmission will persist and spread among the population. (Ross 1911.)
Even scaling-up of current interventions to 100% coverage rates for sustained periods, transmission will still persist in Africa at levels of RC > 1.
Cotton, Malaria, & Pesticide Resistance
FAO in Sri Lanka: IPM + IVM = IPVM
Farmer Field Schools (FFS)
Agriculture-Health Linkages
Uganda National Household Survey 2005/2006
7,426 households interviewed across the country
Rare combination of Questions - Agricultural Questions, Health Questions, and GPS coordinates
5,761 households reported agricultural production data (77%)
Crops Related to Malaria in UgandaCrops measure in comparison to Maize as baseline for crop-risk
Poor Households Middle Households*
Wealthy Households Effect:
Millet - Less Malaria than Maize
Beans - Less Malaria than Maize
Cassava - More Malaria than Maize
Ground-Nuts - More Malaria than Maize
Other Crops - Other Crops More Malaria than Maize
- Sweet Potato More Malaria than Maize
- Tree Crops More Malaria than Maize
* Middle-Wealth households did not have any crop-effects on malaria risk.
LivestockCattle Raising
associated with less malaria for adolescents (age 10 to 19), only in the poorest households
Cattle maybe diverting mosquitos away from humans who tend them - depending on anopheles species
Pig Raising associated with more malaria for adolescents
(age 10 to 19), only in the poorest households
Pigs maybe supporting mosquito populations for humans who tend them- depending on anopheles species.
Integrated Pest Management (IPM) Careful consideration of all available pest control techniques and
subsequent integration of appropriate measures
Discourage the development of pest populations and keep pesticides and other interventions to levels that are economically justified
Reduce or minimize risks to human health and the environment
Emphasizes the growth of a healthy crop with the least possible disruption to agro-ecosystems and encourages natural pest control mechanisms. *FAO
IPM Reduces input cost of PesticideReduces losses from PestsThereby Increases Profit per HectarePrevents / Reduces Pesticide-Resistance
History of Insecticide Resistance & Malaria
1960 & 1970: Insecticide Resistance EmergedTechnical and Financial obstacle to Malaria Control
Central American & India Cotton-growing Areas: Agricultural pesticide application led to resistance in mosquitoes.
WHO & FAO Response Guidance: Attempted to provide unified guidance Creation of IPM by FAO
1973 Banning DDT production in United StatesCosts grew significantly & effectively ended the Global Malaria Eradication Program
DDT use in small quantities for IRS Safe for humans but remains restricted by the WHO but politically sensitive
Anopheline insecticide resistant countries
Africa Asia / Europe Latin AmericaBenin Bangladesh BelizeBurkina Faso Burma Colombia Burundi Cambodia EcuadorCameroon China El SalvadorChad Greece Guatemala Côte d’Ivoire India HaitiEgypt Indonesia Mexico
Equatorial Guinea Iran Panama
Ethiopia Iraq Peru Gabon Laos VenezuelaGambia Malaysia Ghana Nepal Kenya Pakistan
Mali Papua New Guinea
Mozambique Sri Lanka
Nigeria Syria Rep. of Congo Thailand Senegal Turkey South Africa UAE Sudan Vietnam Tanzania Uganda Zambia Zimbabwe
Farmer Field Schools (FFS)Extension approach built upon principles of adult education to social learning
Experiential
Group-based
Participatory
Interactive
Group of farmers get together to study a particular topic.
Conservation / Organic Agriculture, Animal & Soil husbandry income Generating Activities such as handicrafts, etc.
Provides opportunities for ‘learning by doing’ Teaches basic agricultural and management skills for
farmers to become experts in their own farms.
A forum where farmers and trainers debate and share Debate observations and experiences Present new information from outside the community.
Integrated Pest-Vector Management (IPVM)
Program recently developed by FAO and UNEP
Engages communities through Farmer Field Schools in a rational decision making process to achieve the goals of IPM and IVM
FAO – UNEP Pilot program conducted in Sri Lanka from 2002 to 2006:
Sharp drop in insecticide use attributable to the training
Integration of fish (such as tilapia) into rice system to reduce pests and provide dietary protein
Community promotion of bed-nets within village
http://www.who.int/malaria/vector_control/ivm/gpirm/en/
154 Berg Agricultural HallBox: 2207DBrookings, SD 57007 Phone: 605.688.4792 Fax: 605.688.6733
To learn more about: Integrated Pest Management / Extension,
email Darrell Deneke Pesticides,
email Jim Wilson GIS Early Warning for West-Nile Virus / Malaria,
email Michael C. Wimberly
South Dakota State University Resources