Finding Solutions
How can we protect our employees from malaria?
I would like guidance on protecting my non-local staff who are on-site long term
Understanding the risks of malaria in frequent travellers
The incubation period for malaria – the period from infection to the first signs and symptoms – is commonly around 9 – 14 days for falciparum malaria, 12 - 14 days for vivax malaria and 18 – 40 days for malariae malaria. This means that frequent travellers may become infected with malaria in one location but not show symptoms of illness until they reach another location.
With a work-force that may move around regionally or globally it is important to understand this fact, and its implications:
- A malaria infection in a frequent traveller should not be assumed to have arisen in the current location. Assumptions about drug resistance and parasite species should not be based purely on the local context. The possibility that the infection was picked up elsewhere, with a different parasite species ratio and different drug resistance profiles, should be considered.
- Clinic services that serve a community that includes employees who travel frequently, must be able to provide diagnosis and treatment for all malaria species, regardless of the local parasite context.
- Employees on a trip including several malarious areas will need to choose a chemoprophylaxis appropriate to all sites to be visited.
- Employees who travel between malarious and non-malarious sites should remain conscious of the threat of malaria even when in a non-malarious location. It is easy to forget about malaria as a risk when back at a non-malarious home / work location, yet any fever or cold / flu like symptoms in the few weeks and months following a trip to a malarious location should prompt the traveller to seek diagnosis and treatment.
- Travellers should be prepared to brief their practitioners in non-malarious locations about the malaria risk and the need for diagnosis. Emergency standby treatment may be useful to have access to even in locations where you may consider the health services to be of high quality as in non-malarious settings there is often a risk of lengthy delay in suspecting malaria, and diagnosing and treating the disease.
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Personal protection for short term visitors to malarious areas
Short term visitors to a malarious area should all take the following measures to protect themselves from infection and disease:
- Know your setting:
- Know when and where the malaria vectors bite.
- Know which drugs are effective for chemoprophylaxsis and treatment.
- Know where your nearest good quality clinical facility is.
- Know what you will be doing whilst in the malarious area; will you be working outside at night, if so you can prepare by bringing long sleeved clothes and sufficient repellent.
- Click on the black arrows at the bottom of this page for information sheets for visitors to the region. These will need to be supplemented with company specific information.
- Take appropriate chemoprophylaxsis, ensuring it is taken the recommended number of days before arrival and after departure, and that the regimen is followed carefully when in country
- Click here to see a table of effective chemoprophylaxsis by county in the Asia-Pacific region
- Medical advice should be sought to select a drug appropriate to each individual health status.
- Click here to see more information about malaria chemoprophylaxsis
- Use a good quality repellent when outside between dusk and dawn, reapplying it as indicated, more frequently if sweating or after washing or swimming. Read more about using repellents here.
- Sleep under an insecticide treated net whether sleeping indoors or outdoors (read more about ITN section in malaria information section).
PDF For printing for visitors: "Information sheet for visitors to a malarious region"
PDF for printing for visitors: "Malaria in Asia"
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Quality control malaria diagnosis and treatment facilities
Diagnosis
Deciding whether to use RDTs or microscopy or a combination of the two for confirmation of a malaria infection is important but an informed decision relies on the assumption that either of the tools will go on to be used in such a way as to ensure the best performance possible.
Quality control of handling
For RDTs, appropriate transport, storage and handling, in-line with the manufacturer’s recommendations, are important to ensure the RDTs remain stable and achieve their reported levels of sensitivity and specificity (rates of false negatives and false positives).
Guidelines for handling and storage of RDTs should be in place and should include recording of the conditions of storage daily. A supervisory structure should be put in place that allows checking of storage facilities at regular intervals.
The FIND manual on storage, handling and transport of RDTs can be accessed here.
Quality control of RDT use and results
- Regular supervisory checks of clinical services should include observation of RDT use to verify that user instructions are being carefully followed. It is advisable to increase supervision if the RDT product is changed as instructions for use vary from product to product.
- Regular quality assurance of results should be conducted. Blood slides should be prepared at the same time as the RDT test for a random sub-set of people tested for malaria. These should be read by a skilled microscopist (either on-site or by a referral laboratory) to confirm alignment with RDT results.
Quality control of microscopy
A random sub-set of blood smears should be sent for cross-checking by an external microscopist, likely to be available in a referral laboratory within the country. The cross-check results should be compared with the on-site results.
Quality control findings should be carefully reviewed each time to identify needs for remedial training of on-site microscopy staff.
The WHO manual on quality control of malaria microscopy can be accessed here. Whilst it is written for an audience of national managers it includes an overview of all the key steps in a quality control process.
Quality control of use of diagnostic results
Whilst a main focus of diagnostic quality control will be to ensure tests are accurate, it is also important to provide quality control for the second step in the diagnostic process which is ensuring the results are used appropriately.
Health clinic record books should require health staff to record details for every person tested for malaria, the means of testing, the result, the actions taken and the staff member responsible.
These records should be regularly checked as part of the quality control process and remedial training undertaken if appropriate.
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Establishing malaria diagnosis and treatment facilities
Reducing the likelihood of serious illness and death from a case of malaria depends on:
- High quality and appropriate diagnostic services being available
- People with suspected malaria accessing these services
- Case management guidelines being followed by clinical staff
- Treatment being adhered to by patients if not directly administered or observed.
Establishing sound guidelines and high quality facilities are one step in this process, but maintaining quality of services and ensuring communities access facilities are also critical and should also be addressed. Click to access more information on quality control for malaria case management services and on health promotion and communication strategies.
Steps in establishing good quality malaria case management services include:
- Determining the type of malaria parasites found in this site
- Deciding which approach to diagnosis will be taken [Malaria diagnosis requires specialized equipment – either rapid diagnostic tests (RDTs) which require appropriate transport and storage, or microscopy for which both specialized equipment and skills are required. In the Asia-Pacific context where both vivax and falciparum malaria are present and co-infection is common, microscopy may be the best choice where it is considered feasible. RDTs that can differentiate between falciparum and vivax malaria are available but perform less well than good microscopy. ]
Diagnosis guidelines should include:
- Patient characteristics (signs, symptoms, history) that indicate the need for a malaria diagnostic test.
- Procedures for diagnosis including time targets.
- Recording procedures.
- Procedures following a negative result including:
- Time-frame and indicators for repeat testing
- Considerations for alternate diagnosis
- Developing guidelines for transport, storage and handling of RDTs if these are to be used. A good resource for this is available here.
- Deciding which treatment guidelines will be recommended. This should always follow international best practice and almost always be in-line with national treatment guidelines.
This table gives an overview of the interventions which the World Health Organisation recommends for each country in the Asia Pacific regin. The ‘treatment’ section of the table gives details on appropriate treatment and diagnosis. The WHO global malaria report has country profiles, each of which lists the specific drugs which each country has opted for as first line recommended treatment.
However the most complete source of information is the national treatment and diagnosis, or ‘case management’ guidelines which each country develops. A search for the Ministry of Health or National Malaria Control Programme website for your country of operations should guide you to links for national treatment guideline documentation.
Click here to see more about the importance of adhering to international and local guidelines.
Treatment guidelines should include:
- Recommended treatment for each malaria species
- Recommended treatment and clinical management depending on severity of illness: uncomplicated malaria versus severe malaria
- Recommended treatment and clinical management for special groups including those with HIV, pregnant women, young children, those on malaria chemoprophylaxis.
- Detailed referral guidelines.
- Developing a clear, succinct written malaria case management guidelines document for local use (this could be based on international guidelines available here).
- Developing brief job-aides which can be displayed or referred to at the clinic or lab.
- Identifying reliable suppliers of high quality diagnosis and treatment commodities.
- Establishing a quality control strategy
- Developing a communications strategy to ensure all those permitted to access the services are aware of their availability and the basics of the services provided.
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Considering who to make malaria clinical facilities available to.
There are four main options:
- Employees only
- Employees and their families
- All local communities within a specified area
- Anyone who comes to the clinic. (In many areas will add few additional patients to the above, it may therefore be easier to avoid making statements or guidelines about the communities who are permitted to access. This will also avoid the need to verify place of residence).
Reasons to limit access to services could include:
- To reduce the costs associated with use of commodities and other resources
- To reduce the burden on the services in-line with the staff time available
- To reduce the consumption of commodities if these are scarce or there is or is expected to be a supply problem.
However, good reasons for expanding the availability of services as far as possible include:
- The epidemiology of malaria transmission means that control of the disease is most effective if both prevention and treatment services are in place at scale and community-wide. Reducing the parasite reservoir in the local communities by prompt and effective treatment of cases is an important contributing factor to successful malaria control. Extending the availability of services is therefore not purely altruistic but will also likely reduce the impact of malaria within the workforce itself, and thus on the company.
- Availability of high quality malaria case management services is often poor in the rural and remote areas in which many companies work. Making these services available to the local communities is an undeniably useful and potentially high impact option for part of a corporate social responsibility programme.
Options to make some services available more widely and some to a more defined group are also possible. For example, a company might offer diagnostic and out-patient services to local non-employee families but refer them elsewhere for in-patient care if required, while providing full in-patient services as necessary for employees and their family members.
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Health facility based Data collection and analysis for malaria
A range of data should be collected as part of an overall surveillance strategy. Clinical data on people tested and diagnosed as well as the treatments undertaken and if possible the outcomes, are an important part of this surveillance strategy. These data can be used to track burden of disease – in general and in sub-groups – as well as to monitor performance of drugs.
Specific data that should be collected include:
- Details of all people tested for malaria: name, age, sex, occupation, residence, places visited in past month, malaria history. This should be linked to:
- Results of all malaria tests: type(s) of test, person(s) responsible, result(s) and action taken. This should be linked to:
- Results of all malaria treatments given including results of follow-up testing after treatment if recommended.
- Data summaries that will be useful:
- People tested by month and sub-group
- Test positivity rate by month and sub-group
- Number of malaria cases by month and sub-group
Specific uses that these data can be put to include:
- Tracking the disease burden over time. Looking at annual trends to ascertain when any peaks of malaria transmission occur by malaria type. This information can guide control approaches as well as inform commodity supply planning.
- Looking at the malaria incidence rates (number of cases per 1,000 population during a given period) in different sub groups, such as:
- Occupational groups: this could help identify high risk occupations which could benefit from targeted control measures.
- Residence (on-site, off-site or workers who move between locations; different off site locations) this could help identify where transmission is occurring and inform planning of vector control interventions or targeted personal protection for those in or visiting certain sites.
- Those using / not using chemoprophylaxis: this can help determine the effectiveness of the chemoprophylaxis as well as inform analysis of the cost benefits.
- Looking at the total burden of malaria to inform:
- estimates of economic impact of malaria on the company and local communities
- commodity planning
- impact evaluations
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We hope this site has helped given you an overview of the issue of malaria control in the Asia-Pacific, and answered your questions, or given you new ideas. You may now feel well equipt to set up solid programmes to protect your own staff, or to explore opportunities for getting involved outside the fence. If you would still like further support please feel free to get in contact with us.
How malaria consortium can help
How Montrose can help
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How malaria consortium can help
How Montrose can help
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Get guidance on another issue Find out more about malaria Find out where to access more information Find out how to access advice and assistance
Get guidance on another issue Find out more about malaria Find out where to access more information Find out how to access advice and assistance
Note that the information on this website may not be sufficient to guide appropriate approaches since these can be highly specific to the local context so professional advice should be sought.
In the GMS malaria is transmitted mostly by An. dirus and An. minimus which are extremely efficient malaria vectors primarily found in forested and forest fringe areas. Although habits vary both geographically and seasonally, they primarily bite outdoors in the first two quarters of the night. The rate of outdoor early evening biting has increased following the widespread use of LLINs. Despite the reduced level of protection of LLINs, they are still highly recommended although they should be complemented with other measures to combat outdoor transmission. Understanding local vector behaviour is important in the design of an appropriate approach.
Transmission can be intense but is usually highly focal and often sporadic; the high-risk groups include all those spending nights in forest or forest fringe areas. These include forest-based communities (often ethnic minority groups), forest workers (such as soldiers, forest/wildlife protection workers, timber extraction teams, gem miners, wood cutters and hunters), forest fringe agricultural workers (especially seasonal migrants) and rubber tappers).
Recommended options for the GMS setting are:
APMEN has developed country profiles and other summary resources on malaria control with more detailed information specific to countries within the region. You can access these here.
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Greater Mekong Sub-region (GMS)
In the GMS malaria is transmitted mostly by An. dirus and An. minimus which are extremely efficient malaria vectors primarily found in forested and forest fringe areas. Although habits vary both geographically and seasonally, they primarily bite outdoors in the first two quarters of the night. The rate of outdoor early evening biting has increased following the widespread use of LLINs. Despite the reduced level of protection of LLINs, they are still highly recommended although they should be complemented with other measures to combat outdoor transmission. Understanding local vector behaviour is important in the design of an appropriate approach.
Transmission can be intense but is usually highly focal and often sporadic; the high-risk groups include all those spending nights in forest or forest fringe areas. These include forest-based communities (often ethnic minority groups), forest workers (such as soldiers, forest/wildlife protection workers, timber extraction teams, gem miners, wood cutters and hunters), forest fringe agricultural workers (especially seasonal migrants) and rubber tappers).
Recommended options for the GMS setting are:
- Conduct detailed entomological surveys to determine main malaria vectors and their behaviour in the local setting. Although a complete survey is advised, behaviours of particular interest are peak biting times and whether vectors primarily bite and rest indoors or outdoors.
- If entomological surveys show any level of indoor biting or resting then indoor residual spraying may be appropriate for shelters in which people sleep, eat, work or spend their recreational time. Click here for more information on IRS.
- Use indoor residual spraying on the walls and roofs of any semi-outdoor areas such as verandas, covered recreational areas etc. Click here for more information on IRS.
- Fit all doors and windows with mosquito screens. Click here for more information on screening.
- Ensure all staff sleep under insecticide treated mosquito nets whether they are sleeping indoors or outdoors. Alternative designs of insecticide treated nets such as treated hammock nets are available and could be used for workers who tend to sleep outdoors. Click here for more information on ITNs. Consider site location: the further away that sites can be located from forest fringe, the lower the transmission risk is likely to be. On large sites it would be beneficial to locate sleeping areas, evening recreational areas or areas where night time work is carried out as far away from forest cover as possible.
- Personal protection measures should include:
- Use of an appropriate chemoprophylaxis. Click here for more information on chemoprophylaxis and for information on recommended options by country
- Application of repellents in the early evening hours, especially by workers who are typically outside throughout the night (e.g. security guards, night shift workers and those working in or near forested areas). Click here for more information on repellents.
- Consider these other personal protection measures for personnel who spend most of their working hours outdoors during and between dusk and dawn:
- Insecticide treated clothing/ uniforms
- Insecticide treated scarfs or other traditional clothing for those used to wearing these
- Effective case management is an essential element in malaria control. Differential diagnosis is important to identify malaria species and thereby support the selection of an appropriate treatment. It is also essential in order to identify other possible causes of disease. Microscopy is recommended over RDTs if possible provided that robust quality assurance is in place. Click here for more information on malaria case management and click click here to access guidance on setting up locally appropriate treatment approaches.
- Health promotion and communications activities are key to promoting safe prevention and treatment seeking behaviours. Click here for more information on communications components of a control strategy.
APMEN has developed country profiles and other summary resources on malaria control with more detailed information specific to countries within the region. You can access these here.
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Note that the information on this website may not be sufficient to guide appropriate approaches since these can be highly specific to the local context so professional advice should be sought.
Here transmission is dominated by An. culicifacies, An. stephensi and to a lesser extent An. fluviatilis. An. stephensi is the only urban vector. These vectors are common across a range of habitats and transmission is often fairly wide-spread rather than focal. The urban vectors are especially adapted to these contexts and can breed in numerous man-made containers and structures.
In cooler parts of South Asia such as Afghanistan and northern Pakistan, malaria is at the fringe of its range and transmission is fairly unstable and very seasonal, with little to no transmission in the cooler winter months.
These vectors can bite both indoors and outdoors and biting is usually during the late evening and night. They often rest indoors; in rural areas most frequently in livestock sheds. The indoor resting means that indoor residual spraying can be highly effective in these areas. Insecticide treated nets are also useful and where people sleep outside during the hotter months outdoor use of nets has been successfully promoted. Depending on the result of entomological surveys and on the context, larval control through environmental management or larviciding can sometimes be useful.
Recommended options for the South Asia setting are:
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South Asia Sub-region
Here transmission is dominated by An. culicifacies, An. stephensi and to a lesser extent An. fluviatilis. An. stephensi is the only urban vector. These vectors are common across a range of habitats and transmission is often fairly wide-spread rather than focal. The urban vectors are especially adapted to these contexts and can breed in numerous man-made containers and structures.
In cooler parts of South Asia such as Afghanistan and northern Pakistan, malaria is at the fringe of its range and transmission is fairly unstable and very seasonal, with little to no transmission in the cooler winter months.
These vectors can bite both indoors and outdoors and biting is usually during the late evening and night. They often rest indoors; in rural areas most frequently in livestock sheds. The indoor resting means that indoor residual spraying can be highly effective in these areas. Insecticide treated nets are also useful and where people sleep outside during the hotter months outdoor use of nets has been successfully promoted. Depending on the result of entomological surveys and on the context, larval control through environmental management or larviciding can sometimes be useful.
Recommended options for the South Asia setting are:
- Conduct detailed entomological surveys to determine main malaria vectors and their behaviour in the local setting. Although a complete survey is advised, behaviours of particular interest are: the distribution and type of larval breeding sites, level of preference for human hosts and night biting behaviour (time and location).
- Indoor residual spraying of walls and ceilings in dwellings, livestock sheds and shelters. Click here for more information on IRS.
- Fit all doors and windows with mosquito screens. Click here for more information on screening.
- Ensure all staff sleep under insecticide treated mosquito nets whether they are sleeping indoors or outdoors. Alternative designs of insecticide treated nets such as treated hammock nets are available and could be used for workers who tend to sleep outdoors. Click here for more information on ITNs.
- Based on the result of the entomological surveys, larval control measures may be appropriate in some settings, particularly urban settings or areas which are predominantly dry with few breeding sites.
- Personal protection measures should include:
- Use of an appropriate chemoprophylaxis. Click here for more information on chemoprophylaxis and for information on recommended options by country
- Where malaria transmission is highly seasonal, seasonal chemoprophylaxis could be considered.
- Application of repellents in the early evening hours and later at night for those who are exposed to vector biting, especially by workers who are typically outside throughout the night (e.g. security guards and night shift workers). Click here for more information on repellents.
- Effective case management is an essential element in malaria control. Differential diagnosis is important to identify malaria species and thereby support the selection of an appropriate treatment. It is also essential in order to identify other possible causes of disease. Microscopy is recommended over RDTs if possible provided that robust quality assurance is in place. Click here for more information on malaria case management and click click here to access guidance on setting up locally appropriate treatment approaches.
- Health promotion and communications activities are key to promoting prevention and safe treatment seeking behaviours. Click here for more information on the communications component of a control strategy.
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Note that the information on this website may not be sufficient to guide appropriate approaches since these can be highly specific to the local context so professional advice should be sought.
The epidemiology of malaria in the Pacific sub-region is highly complex due in part to the diversity of behaviours exhibited by the different sibling species that make up the An. farauti and An. punctulatus species complexes. Breeding site selection, which is often determined by tolerance to salinity, and adult feeding behaviour varies throughout the region. These behaviours have a major effect on transmission patterns; in some settings for example, transmission takes place mostly in coastal areas. However, some generalizations can be drawn. In most areas a significant proportion of transmission occurs indoors late at night, which means that the use of insecticide treated nets should have a strong protective effect. Some indoor resting occurs in most areas and so IRS is also generally useful.
Larval control may be feasible in defined areas where all breeding sites can be mapped and accessed. However, generally this approach is not feasible as most vectors breed in a range of small, scattered temporary pools. Measures should be taken to avoid the creation of new breeding sites (during construction work for example) since An. punctulatus can rapidly increase in numbers in response to a proliferation of breeding sites.
In some countries, such as the Solomon Islands, wide-spread use of insecticide based control measures has reduced the importance of An. punctulatus as a vector, but has also resulted in a shift in the biting behaviour of An. farauti, which now bites earlier and outdoors. This means that ITNs and IRS alone are insufficient to provide full protection against malaria.
Recommended options for the Pacific setting include:
Special case: Indonesia Indonesia has a particularly complex malaria profile and here generalizations are more difficult to make than elsewhere.
Indonesia spans the Asia and Pacific sub-regions and has a large number of malaria transmission profiles. Bali, Java and Batam have low transmission. Sumatra, Kalimantan and Sulawesi have moderate transmission. All other provinces have moderate to high transmission.
There is high diversity of vector species on the major islands. For example, in Sumatra, An. sinensis is found inland along with the An. barbirostris complex, An. leucosphyrus/An. latens and the An. minimus complex. A number of other vector species also exist on Sumatra but none are considered dominant on the island; hence they are over- laid by the other, more dominant species. Alongside the An. sundaicus complex distributed along the coast, An. flavirostris does increase in relative ‘dominance’, by virtue of a reduced presence of other species, extending southward through Java until it is the only dominant vector species found in the Lesser Sunda islands. In Sumatra, there is very little overlap amongst the dominant species found, suggesting that each occupies a separate niche. Anopheles balabacensis dominates across most of Borneo, with some impact by the An. barbirostris complex and An. leucosphyrus/latens inland and the An. sundaicus complex on the coast. This APMEN profile gives more detail about the complex Indonesian setting.
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Pacific Sub-region
The epidemiology of malaria in the Pacific sub-region is highly complex due in part to the diversity of behaviours exhibited by the different sibling species that make up the An. farauti and An. punctulatus species complexes. Breeding site selection, which is often determined by tolerance to salinity, and adult feeding behaviour varies throughout the region. These behaviours have a major effect on transmission patterns; in some settings for example, transmission takes place mostly in coastal areas. However, some generalizations can be drawn. In most areas a significant proportion of transmission occurs indoors late at night, which means that the use of insecticide treated nets should have a strong protective effect. Some indoor resting occurs in most areas and so IRS is also generally useful.Larval control may be feasible in defined areas where all breeding sites can be mapped and accessed. However, generally this approach is not feasible as most vectors breed in a range of small, scattered temporary pools. Measures should be taken to avoid the creation of new breeding sites (during construction work for example) since An. punctulatus can rapidly increase in numbers in response to a proliferation of breeding sites.
In some countries, such as the Solomon Islands, wide-spread use of insecticide based control measures has reduced the importance of An. punctulatus as a vector, but has also resulted in a shift in the biting behaviour of An. farauti, which now bites earlier and outdoors. This means that ITNs and IRS alone are insufficient to provide full protection against malaria.
Recommended options for the Pacific setting include:
- Conduct detailed entomological surveys to determine main malaria vectors and their behaviour in the local setting. Although a complete survey is advised, behaviours of particular interest are the distribution and type of larval breeding sites as well as biting behaviour (time and location).
- Indoor residual spraying on the walls and ceilings of houses and any semi-outdoor areas such as verandas, covered recreational areas etc. in which people spend time at night sleeping, eating, working or relaxing. Click here for more information on IRS.
- Fit all doors and windows with mosquito screens. Click here for more information on screening.
- Ensure all staff sleep under insecticide treated mosquito nets whether they are sleeping indoors or outdoors. Alternative designs of insecticide treated nets such as treated hammock nets are available and could be used for workers who tend to sleep outdoors. Click here for more information on ITNs.
- Personal protection measures should include:
- Use of an appropriate chemoprophylaxis. Click here for more information on chemoprophylaxis and for information on recommended options by country. Where malaria transmission is highly seasonal, seasonal chemoprophylaxis could be considered.
- Application of repellents in the early evening hours and later at night for those who are exposed to vector biting, especially by workers who are typically outside throughout the night (e.g. security guards and night shift workers). Click here for more information on repellents.
- Effective case management is an essential element in malaria control. Differential diagnosis is important to identify malaria species and thereby support the selection of an appropriate treatment. It is also essential in order to identify other possible causes of disease. Microscopy is recommended over RDTs if possible provided that robust quality assurance is in place. Click here for more information on malaria case management and click click here to access guidance on setting up locally appropriate treatment approaches.
- Health promotion and communications activities are key to promoting prevention and safe treatment seeking behaviours. Click here for more information on the communications component of a control strategy.
Special case: Indonesia Indonesia has a particularly complex malaria profile and here generalizations are more difficult to make than elsewhere.
Indonesia spans the Asia and Pacific sub-regions and has a large number of malaria transmission profiles. Bali, Java and Batam have low transmission. Sumatra, Kalimantan and Sulawesi have moderate transmission. All other provinces have moderate to high transmission.
There is high diversity of vector species on the major islands. For example, in Sumatra, An. sinensis is found inland along with the An. barbirostris complex, An. leucosphyrus/An. latens and the An. minimus complex. A number of other vector species also exist on Sumatra but none are considered dominant on the island; hence they are over- laid by the other, more dominant species. Alongside the An. sundaicus complex distributed along the coast, An. flavirostris does increase in relative ‘dominance’, by virtue of a reduced presence of other species, extending southward through Java until it is the only dominant vector species found in the Lesser Sunda islands. In Sumatra, there is very little overlap amongst the dominant species found, suggesting that each occupies a separate niche. Anopheles balabacensis dominates across most of Borneo, with some impact by the An. barbirostris complex and An. leucosphyrus/latens inland and the An. sundaicus complex on the coast. This APMEN profile gives more detail about the complex Indonesian setting.
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Community-wide transmission of malaria and considering a buffer zone.
Although most mosquito vectors of malaria have a flight range of around 2km, this can vary considerably (for instance, one of the major Pacific vectors has an average flight range of about half this) and flight ranges greater than about 5km are not usual. Mosquitoes can spread malaria within their flight ranges so a new works site for example located within a few kilometres of an endemic community can quickly become a focus of transmission.
In areas of high transmission older children and adults develop a high degree of immunity to the disease and harbour parasites without developing symptoms. These individuals act as a permanent reservoir of parasites for the local mosquito vectors to pick up and pass on.
When considering site-wide vector control approaches, it is often wise to consider expanding control efforts into the surrounding communities to create a buffer zone of lowered transmission around the site. Where IRS is used this is particularly important since this control approach relies on achieving a community-wide impact on the mosquito vector population, shortening the average mosquito life span so that individual mosquitoes don’t live long enough for the parasite to have sufficient time to develop in the mosquito and be passed on.
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