Plasmodium falciparum malaria remains endemic in sub-Saharan Africa 1 . In Ghana, the burden of malaria remains high with about 323 per 1,000 cases reported among children < 5 years in 2008; and there is limited evidence of a decrease in recent years (2002 - 2008) 2 . Malaria studies carried out in the middle belt of Ghana report of high transmission of approximately 269 infective bites per person per year and a parasite prevalence of not less than 50% at all times in the year among children < 5 years 3 . The burden of malaria in Ghana and other endemic countries will continue to result in anaemia, cerebral malaria, and severe malaria, if the use of currently available tools for malaria interventions such as rapid diagnosis and appropriate treatment, use of insecticide-treated nets (ITNs) and indoor residual spraying are not intensified as part of the strategies to control malaria. A complex matrix of factors could mitigate the successful use of the available tools; of special note are access to health care, household socioeconomic status, parental formal education, health education about malaria control and nutritional status of individuals. However, there have been reports of encouraging malaria control efforts in some countries in sub-Saharan Africa, including Zanzibar 4 , Kenya 5 6 and Tanzania 7 , which can be replicated in other African countries given the resources from public and private partnerships and political commitment available recently.

Newmont Ghana Gold Limited, a mining company in Ghana 8 recognizes that its mining activities may have an impact on malaria and other public health diseases in the mining area. For example, mining activities could alter the breeding potential of mosquitoes as well as increase migration into the mining area and this could precipitate poor environmental factors that may lead to diseases including malaria. Alternatively, environmental alterations as a result of urbanization and the mining activities may decrease mosquito breeding sites and, therefore, the burden of malaria.

With this realization, the Ghana Health Service in partnership with Newmont Ghana Gold Limited conducted a household and malaria epidemiology study as a baseline prior to the start of mining activities of Newmont Ghana Gold Limited in 2006/2007 to plan and evaluate malaria control programme within the area. This effort to control malaria in a mining area builds on a similar partnership in another mining area in Obuasi, Ghana that has led to a successful malaria control programme in the area 9 . This baseline malaria epidemiological data will be used for monitoring and evaluating malaria interventions specifically targeted at the mining area. The Ahafo baseline data are being reported in further attempts to contribute to the body of data required for monitoring global malaria burden.

The study assessed the epidemiology of malaria in a rural forest area of the Brong Ahafo region in Ghana. The prevalence of malaria parasitaemia and anaemia among children less than five years and malaria entomology were determined. Though renewed efforts in controlling malaria in sub-Saharan Africa has led to reports of decline in the burden of malaria in some parts of Africa 4 5 6 7 9 , there is little evidence in Ghana to suggest a decline in out-patient attendance due to malaria and malaria mortality amidst the intensified delivery of malaria control interventions 2 . In this survey, a malaria epidemiology survey in a forest area of Ghana including a mining area was conducted to plan malaria control programmes in these areas.

The prevalence of P. falciparum among children gives an estimation of the burden of malaria in a particular area. In the study area, the prevalence of malaria parasitaemia was relatively low 22.8% (95% CI 20.8 - 24.9) compared to reports from other rural parts of Ghana; 58% in a forest savanna transitional area of Kintampo in 2004 3 ; between 55.5 - 69.3% in savanna area in northern Ghana between 2000 and 2002 15 16 . The prevalence of malaria parasitaemia in the area was however comparable to reports in urban semi-humid areas - 12.8% - 37.8% in 2005 17 .

The relationship between malnutrition and malaria are inconsistent in the literature. Studies conducted in Ethiopia 18 and southern Ghana 19 showed no evidence of relation between malnutrition and anaemia contrary to studies conducted in urban Equatorial Guinea 20 , in western Kenya 21 and reviews by Caulfield et al 22 that suggest a strong relationship between malnutrition and malaria. In this study, there was no association of malaria parasitaemia with malnutrition.

In 2003, the government of Ghana introduced the National Health Insurance Scheme with the aim of reducing financial constraints as a gap in accessing health. Household membership of the insurance scheme provides children to seek health in health facilities closest to them. Common illnesses, such as malaria, are treated without direct cash payment at the point of service. In this study, health insurance membership was protective against malaria parasitaemia but had no significant relationship with anaemia. Participants who subscribe to the health insurance may regularly seek health care and may have been treated for malaria thus, the observed protection of malaria parasitaemia by health insurance membership.

ITNs are known to prevent malaria infection by reducing human contact with the malaria vector and thus able to reduce all-cause mortality in children less than five years old by 17% in northern Ghana 23 and about 44% in Kenya 24 . ITN ownership has increased in recent times due to the support of local government and international donors such as USAID and their private partners 25 . In 2003, ITN ownership in Ghana was less than 10% but had increased to about 33% in 2008 26 . In this study ITN ownership (at least one) was lowest in the Asutifi area (range 43% - 53.3%) compared to 76.8% in the Techiman area. This difference in household ITN ownership was due to mass distribution of ITNs to all households with children less than two years as part of Child Survival strategies throughout Ghana. The relatively low coverage in Asutifi is because this survey was carried out prior to the free distribution of treated bed-nets in the Child Survival Campaign. The coverage determined in the study area are similar to the coverage of 45.6% assessed in 2008 for the same area during the Ghana Health and Demographic Survey 26 . The coverage of ITNs could further be increased and maintained at the World Health Organization target of ≥80% if private companies such as Newmont Ghana Gold Limited and other partners could support the Ghana Health Service and the communities with additional ITNs.

Despite the benefits of ITNs in controlling malaria, its patronage has not been quite encouraging and its usage is for some reasons other than for malaria control. For instance, in Savalou, Benin mosquito nets were often seen as a means of protection against mosquitoes and other biting insects in order to sleep better rather than as a means of preventing malaria 27 . Several reasons including: lack of money or expensive ITN, unavailability of ITN, no provision for nets to fit sleeping space account for the low mosquito net usage. In this study, it was encouraging to note that ITN use was high; about 86.4% (95% CI 84.3 - 88.4) of household that owned ITNs had at least one person sleeping under an ITN the night before the interview. This is consistent with the high coverage of ITN use among children in the same area determined in 2008 26 . Though there was a high ITN ownership and use, there was no evidence of protection against malaria parasitaemia after adjusting for age, anaemia, malnutrition and other household. This may be due to poor quality of ITNs (about 18% of household nets had holes) or improper use of ITNs.

One of the commonest causes of anaemia in sub-Saharan Africa is malaria. In this study, the prevalence of anaemia among all children < 5 years was moderately high 30.5% (95% CI 28.2 - 32.8) with children less than 24 months having a higher risk of anaemia. Although high, it is still lower than reported in other parts of Ghana and follows the same trend as malaria parasitaemia 3 15 16 28 . There are other causes of anaemia in children such as malnutrition, hookworm infection, and sickle cell disease but their contribution to anaemia in malaria endemic regions has been found to be minimal compared malaria 29 30 . In this study, there was a weak-association between abnormal height for age scores and anaemia; and a stronger association between malaria parasitaemia and anaemia after adjusting for age, ITN use and other household characteristics. Other common causes of anaemia such as hookworm infestation and sickle cell disease were not determined in this study.

There are few longitudinal malaria entomology studies carried out in mining communities in Ghana and other parts of the world. The abundance of mosquitoes in the Asutifi and Tano N/S districts differed slightly due to several contributing factors. Unlike Asutifi where the mosquito abundance was highest in the impact area, Tano experienced the reverse within the six month surveyed period. Though reasons for these differences in vector densities were not investigated, they may be attributed to environmental factors, such as changes in climate or vegetation, rainfall pattern, temperature; human factors such as human created breeding sites from urbanization; and intrinsic vector characteristics as previously reported 31 32 .

The EIRs calculated in this survey were as high as the EIRs found in the Kintampo area (269 ib/p/y) two years prior to this survey and used as an estimate for the control. The high EIRs recorded occurred in months that experienced moderate rainfall; June-July in Asutifi and February-May in Tano N/S, which indicates the impact of rainfall in vector populations and their breeding potential. Moderate rainfall creates pockets of water which favours breeding of larvae unlike torrential rains which washes away larval breeding sites of the major malaria vectors in Africa 32 . As such, changes in vegetation or environment that promotes moderate rainfall could possibly begin to experience high malaria transmission if appropriate vector control activities are not planned. EIRs varied significantly between areas or communities and, therefore, control strategies need to be planned in concert with detail area vector indices such as abundance, speciation and EIRs. The low infectivity rate of An. funestus in this survey may probably be because a large proportion of young vectors with a low potential to transmit malaria may have been caught in the light traps; however this could not be confirmed since samples were not subjected to physiological age grading technique (parity detection) in this study. All An. gambiae s. l. analysed by PCR were of the S-molecular forms which is widespread in West Africa and other parts of Africa including the Kintampo area estimated for the control area 31 32 33 34 35 .

The high percentage of kdr+ mutation reported in this study should prompt the malaria control programme to mount a surveillance on insecticide resistance existing especially since there could be an exacerbation due to the potential of cross-resistance between the insecticides used for farming and ITNs in this predominantly farming area.

At the time of the survey in 2006, the study area in the Asutifi and Tano N/S districts were being prepared for mining activities by Newmont Ghana Gold Limited. Part of the mining preparatory activities may include clearing away some forest vegetation that could potentially lead to clean water pools and subsequently change the breeding characteristics for mosquitoes that could transmit malaria and other vector borne diseases such as Yellow fever and Dengue if left unmanaged. This phenomenon of mosquito scourge associated with industrial activities was reported many years ago in the Panama Canal 36 and recently in the copper mines of DRC and Zambia 37 38 . In both cases, the industrial activity was significantly affected until an effective malaria control programme including environmental vector control was implemented. In the Zambian case, copper production increased significantly with declining burden of malaria, thus paying off the investment made in the malaria control. Additionally, a mining area has the potential of attracting migrant workers which increases the population with poor sanitation if uncontrolled.

This malaria survey was conducted as part of preparatory activities to control malaria and other potential vector borne diseases in the area. It demonstrates the mining company's commitment in controlling malaria in their area of operations while protecting its workforce to minimize cost due to healthcare and maximize productivity. Newmont Ghana Gold Limited and the Ghana Health Service have intensified malaria control activities in the area since the completion of the survey. These activities include in-door residual spraying, larviciding, free ITN distribution to employees (three ITNs per employee) and community members (two ITNs per household); refurbishment of a community health centre and training of health staff for accurate malaria diagnosis 39 . The impact of the interventions in the community is yet to be evaluated; however, a marked decrease (8% in 2006 to 1.8% in 2009) in malaria incidence among the mining work force has been noted 40 . Newmont Ghana Gold Limited's support to control malaria and other public health diseases, such as tuberculosis and HIV/AIDS, has been recognized by the Global Business Coalition on HIV/AIDS, Tuberculosis and Malaria in 2010 40 . Similar private cooperate involvement in malaria control has successfully been supported by companies, such as Anglogold Ashanti in Obuasi area of Ghana 9 , Konkola Copper Mine in Zambia 41 and Exxon Mobil in Angola, Cameroon, Chad, Equatorial Guinea and Nigeria 42 .

The malaria epidemiology suggests a high malaria transmission in the mining area prior to the start of mining activities. Efforts at controlling malaria in this mining area have been intensified but could be enhanced with increased resources and partnerships between government and the private sector. Periodic evaluations will be key to ascertain the impact of the malaria control activities currently ongoing in the mining area.

The authors declare that they have no competing interests.

KPA led in the proposal writing with contribution from CM, CZ, GK, KT, DD and SOA. KPA, CZ, DD, and KT coordinated the data collection during the study with support from YAD and CA on behalf of Newmont Ghana Gold Limited. Laboratory analysis was performed by DBD, CB, KT and DD. Data management and analysis was done by KPA, GD, MA, SAE and SOA. KPA wrote the manuscript with contribution from all authors. All authors read the final version of the manuscript.