malaria case study

Slide 1

• MALARIA CASE STUDY
• (INFECTIOUS DISEASE)

What is malaria?

• = vector-borne disease, caused by parasites and biologically transmitted by mosquitoes (female anopheles)
• - according to WHO about 3.4 billion live at risk of malaria transmission, Sub-Saharan Africa has the highest concentration
• - children under the age of 5, the elderly and pregnant women are most at risk
• = the 6th biggest killer in LIC's
• symptoms: fever, fatigue, shaking chills, muscle disease ,headaches & vomiting
• complications: severe anaemia, cerebral malaria, liver & kidney failure, dehydration, shock

Links to the physical environment:

• malaria = strongly linked to natural environment
• - mainly affects countries in the Tropics & sub-tropics, especially those closest to equator & higher latitudes and higher altitude are unaffected
• - mosquitoes breed in stagnant water & transmission = greatest in areas during & just after rainy season, * but with tropical regions with little seasonal variation in climate, risk of malaria = all year round
• * low-lying areas are turned into wetlands providing an ideal habitat for breeding
• - parasites require temperatures of between 16C and 32C to develop in mosquito
• - coastal areas often show a higher prevalence of the disease as they have much less seasonal variation, lower in altitude & higher relative humidity
• - studies in India have shown that those living in proximity to forested areas are more susceptible to infection (humidity)
• - period of long term drought

Links to socio-economic environment

• - malaria is frequently referred to as a disease of poverty
• - malaria = common cause of morbidity in many countries, but concentrated in poorest due to lack of investment in projects developing new drugs, vaccines & limited number of existing programmes to control disease
• housing quality & occupancy:
• - homes = earth/sand floors with mud, bamboo cane/wooden trunks for walls & grass/palm leaves for roofs, overcrowded rooms & densely clustered built up areas
• unsanitary conditions:
• - areas are dirty, polluted by rubbish & waste outflows, spitting & open defecation attracts mosquitoes
• occupation:
• - agricultural workers more exposed to mosquito vector, e.g. those living near stores of irrigation water or migrant workers who sleep outdoors at night, e.g. studies in Ethiopia have shown highland farmers who seasonally migrate to find work in lowland workers are prone to malarial infection
• rural vs urban
• - in general those in rural areas are seen to be more at risk but contamination rates in urban slums & squatter settlements are high due to density of households & unsanitary conditions

Impacts on health & well-being

• - kills a child somewhere in the world every minute
• - 90% of malaria deaths occur in africa where malaria accounts for 1 in 6 deaths of children
• - contributes greatly to anaemia among children - major cause of poor growth & development
• - burden on local health care systems
• - malaria illness & death cost Africa approx $12 billion each year in lost productivity, effects permeate almost every sector:
• - increases school & work absenteeism
• - decreases tourism
• - inhibits foreign investment
• - affects crop production

Impacts on economic well-being:

• - strong argument that malaria causes underdevelopment
• - costs to individuals & families = purchase of drugs for treating malaria, expense for travel to & treatment @ clinic, lost days of work, reduction in crop production, expenses for burial
• - costs to governments = maintenance, supply or staffing of health facilities, purchase of drugs & supplies, public health interventions against malaria, e.g. insecticide spraying or distribution of nets, lost opportunities for tourism
• - estimated in some areas malaria accounts for up to 40% of public health expenditures
• - cost in economic growth many times more than direct costs ($12 billion)

How can malaria be prevented? (mitigation)

• WHO suggests the key interventions to control malaria are:
• - prompt & effective treatment with artemisinin-based combination therapies
• - use of insecticidal nets by people at risk
• > seen as an effective, low cost strategy, can reduce malaria transmissions by 90% in areas with high coverage rates
• > create a protective barrier against deadly malaria-carrying mosquitoes that typically bite @ night
• > insecticide woven into nets kill mosquitoes (so cannot bite others who may not be protected)
• - indoor residual spraying with insecticide to control vector mosquitoes
• > can be very expensive & has to be repeated several times a year (before mosquito season)
• > effective way of killing large numbers, but only if done properly
• > chemicals can have ecological effects & impacts on peoples health, e.g. DDT kills aquatic insects & fish & can lead to cancers & miscarriages
• > mosquitoes can evolve resistance to insecticides, so new ones have to be developed
• - in many parts of world, parasites have developed resistance to malaria treatments so holistic approach offers better protection
• - burning mosquito coils favoured in urban areas in asia & south america where they are readily available & relatively affordable
• > emit a repellent smoke, but been discouraged by some health authorities as smoke may contain pollutants which are of health concern
• despite being treatable & preventable, it continues to have devastating impacts on peoples health & livelihoods around the world
• > where malaria = endemic, it disproportionately affects poor & disadvantaged
• - giving anti-malarial drugs or vaccines to vulnerable people

Management:

• - great progress has been made in tackling malaria in last 15 years
• e.g. adoption of millennium development goals in 2000 & roll back malaria partnerships have reduced cases significantly
• - between 2000 & 2012 42% decline in malaria mortality rates globally
• - in 2000 3.3 million deaths from malaria were averted & lives of 3 million children were saved
• - WHO has set up new strategy: by 2020 reduce burden by 40% & by at least 90% by 2030, aims to eliminate the disease in at least 30 new countries by 2030

How did Sri Lanka becoming malaria free?

• - strategy shift in 90s to intensively target the parasite & mosquito
• - created mobile malaria clinics in high transmission areas
• > prompt & effective treatment
• > reduce chance of further transmission
• - surveillance, community engagement & health education
• - government prioritised the problems & funded it
• - there was 264,549 cases in 1999 and 0 in november 2012

Climate change & malaria

• - likely to be the vector-borne disease most sensitive to long-term climate change
• - link between climatic events has long been studies in India
• e.g. early last century excessive monsoon rainfall & high humidity was identified early on as a major influence enhancing mosquito breeding & survival
• - globally, temp increases of 2-3C would increase number of people who, in climatic terms, are at risk of malaria by 3-5%, e.g. several hundred million (according to IPCC without additional measures to reduce ghg emissions Earth temps will increase by 3.7-4.8C), seasonal duration would increase in many current endemic areas
• - Intergovernmental Panel on Climate Change (IPCC), changes in temp & rainfall will affect natural habitats of mosquitoes, changing prevalence of vector or prolonging transmission season & exposing new regions & populations to malaria & other vector-borne diseases
• - WHO & World Meteorological Organisation have identified malaria as one of the most climate-sensitive diseases with evidence providing associations with changes in temperature, rainfall, humidity & malaria incidence
• - World Bank says by 2050 climate change will cause a 50% higher probability of malaria transmission in previously unexposed areas of South America, Sub-Saharan africa & China
• - Between 2010 & 2014 WHO carried out climate change & human health adaption project in 6 pilot countries, e.g. Kenya sought to identify & share solutions to address health risks exacerbated & caused by climate change & variability
• impact of regional climate change on malaria risk due to greenhouse gases forcing land-use changes in tropical africa:
• - study assessed potential changes in malaria transmission via intergrated weather-disease model & concluded climate changes driven by ghg & land-use changes will significantly affect spread of malaria in tropical Africa well before 2050
• impact of climate change on global malaria distribution
• - first multi-malaria model comparison exercise, estimate impact of future climate change & population scenarios on malaria transmission @ global scale, results show climate might become more suitable for malaria transmission in tropical highland regions, but other important socio-economic factors (e.g. land-use changes, urbanisation) will need to be factored into future risk assessments