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Early warnings of the potential for malaria transmission in rural Africa using the hydrology, entomology and malaria transmission simulator (HYDREMATS)
Teresa K Yamana, Elfatih AB Eltahir
Malaria Journal , 2010, DOI: 10.1186/1475-2875-9-323
Abstract: HYDREMATS is used to make predictions of mosquito populations and vectorial capacity for 2005, 2006, and 2007 in Banizoumbou village in western Niger. HYDREMATS is forced by observed rainfall, followed by a rainfall prediction based on the seasonal mean rainfall for a period two or four weeks into the future.Predictions made using this method provided reasonable estimates of mosquito populations and vectorial capacity, two to four weeks in advance. The predictions were significantly improved compared to those made when HYDREMATS was forced with seasonal mean rainfall alone.HYDREMATS can be used to make reasonable predictions of mosquito populations and vectorial capacity, and provide early warnings of the potential for malaria epidemics in Africa.The Roll Back Malaria (RBM) initiative has published a framework for malaria early warning systems (MEWS) in Africa [1]. These systems rely on indicators of vulnerability, transmission risk and early case detection in order to predict the onset and severity of malaria epidemics. Monitoring rainfall has been recognized as an essential component for MEWS and is being used by malaria control programmes in a number of African countries [2]. Hay et al [3] retrospectively determined that monitoring dekadal (every 10 days) estimates of rainfall anomalies provided by the Africa Data Dissemination Service (ADDS) could have provided a reliable warning of a major malaria epidemic that occurred in 2002 in Kenya. Thomson et al [4] suggested that in Botswana, rainfall from December through February could be used to give an early warning for high transmission years.While excess rainfall is often associated with increased malaria transmission, this is not always the case. For example, heavy rainfall associated with the 1997-98 El Nino event was associated with decreased malaria transmission in the highlands of Tanzania, presumably by washing away larval breeding sites [5]. Similarly, decreases in rainfall have been observed to increase mal
Malaria hotspot areas in a highland Kenya site are consistent in epidemic and non-epidemic years and are associated with ecological factors
Kacey C Ernst, Samson O Adoka, Dickens O Kowuor, Mark L Wilson, Chandy C John
Malaria Journal , 2006, DOI: 10.1186/1475-2875-5-78
Abstract: To address this issue, spatial distribution of malaria incidence and the relationship of ecological factors to malaria incidence were assessed in the highland area of Kipsamoite, Kenya, from 2001–2004.Clustering of disease in a single geographic "hotspot" area occurred in epidemic and non-epidemic years, with a 2.6 to 3.2-fold increased risk of malaria inside the hotspot, as compared to outside the area (P < 0.001, all 4 years). Altitude and proximity to the forest were independently associated with increased malaria risk in all years, including epidemic and non-epidemic years.In this highland area, areas of high malaria risk are consistent in epidemic and non-epidemic years and are associated with specific ecological risk factors. Ongoing interventions in areas of ecological risk factors could be a cost-effective method of significantly reducing malaria incidence and blunting or preventing epidemics, even in the absence of malaria early warning systems. Further studies should be conducted to see if these findings hold true in varied highland settings.It has been estimated that 34 million individuals in highland areas of East Africa are at risk for malaria [1] and malaria in these highland areas has been responsible for numerous deaths [2]. However, the levels of variation in malaria risk within these highland areas are not well described and only a few studies have investigated risk factors for malaria there [3-5]. Previous studies have demonstrated that malaria cases aggregate from the household to the countrywide level [3,6,7]. The determinants of such clustering are likely due to shared anthropogenic and environmental variables, as well as factors related to contagion such as population density and human interactions [8,9]. Brooker et al demonstrated that there was spatial clustering of malaria cases in children during an epidemic in a single year in highland area of Kenya [3]. However, without data from multiple years, it is difficult to discern if clusters of
Enhancing malaria control using a computerised management system in southern Africa
Marlize Booman, Brian L Sharp, Carrin L Martin, Bonifacio Manjate, Jacobus J la Grange, David N Durrheim
Malaria Journal , 2003, DOI: 10.1186/1475-2875-2-13
Abstract: Successful development and application of a computerised spraying operations management system in Mpumalanga Province, South Africa during 1998 resulted in its adaptation and introduction in neighbouring Maputo Province, southern Mozambique during 2000. The structure and components of this computerised management system are described, and its' operational benefit in southern Mozambique, where community-based spray operators apply intradomiciliary insecticide, are reviewed.The computerised management system allowed malaria programme management and field supervisors to monitor spraying coverage, insecticide consumption and application rates on an ongoing basis. The system supported a successful transition to community-based spraying, while assuring correct insecticide application and spraying completion according to schedule.In 1946, South Africa introduced intradomiciliary spraying with residual insecticides, DDT (dichlorodiphenyltrichloroethane) and BHC (Benzene hexachloride), to kill indoor-resting vector mosquitoes and thereby control malaria [1]. This resulted in a 75 percent reduction in the geographic extent of the malaria-affected area, with malaria occurrence limited to summer epidemics in the low-lying northern and eastern border areas with Botswana, Zimbabwe and Mozambique [2,3]. Similar malaria control programmes were initiated in other southern African countries. In Mozambique, spraying operations for malaria control collapsed during the 1970s due to the protracted civil war with a resulting high burden of endemic malaria throughout the country [4].Recently there has been a resurgence of malaria in southern Africa, attributed to a number of factors, including parasite drug-resistance, mosquito insecticide-resistance, climate changes and large-scale population migration [3,5]. The HIV/AIDS epidemic has resulted in a simultaneous dwindling of resources available for public health programmes, thus placing an onus on programme managers to ensure optimal effic
Improving epidemic malaria planning, preparedness and response in Southern Africa
Joaquim DaSilva, Brad Garanganga, Vonai Teveredzi, Sabine M Marx, Simon J Mason, Stephen J Connor
Malaria Journal , 2004, DOI: 10.1186/1475-2875-3-37
Abstract: The SADC countries have adopted the Abuja targets for Roll Back Malaria in Africa, which include improved epidemic detection and response, i.e., that 60% of epidemics will be detected within two weeks of onset, and 60% of epidemics will be responded to within two weeks of detection. The SADC countries recognize that to achieve these targets they need improved information on where and when to look for epidemics. The WHO integrated framework for improved early warning and early detection of malaria epidemics has been recognized as a potentially useful tool for epidemic preparedness and response planning. Following evidence of successful adoption and implementation of this approach in Botswana, the SADC countries, the WHO Southern Africa Inter-Country Programme on Malaria Control, and the SADC Drought Monitoring Centre decided to organize a regional meeting where countries could gather to assess their current control status and community vulnerability, consider changes in epidemic risk, and develop a detailed plan of action for the forthcoming 2004–2005 season. The following is a report on the 1st Southern African Regional Epidemic Outlook Forum, which was held in Harare, Zimbabwe, 26th–29th September, 2004.The Southern African region has a long and varied history of malaria control with periodic epidemics occurring [1,2]. These epidemics can be regional in scale, as in 1996 and 1997, or much more focal, affecting specific districts or sub-districts. The countries of the Southern African Development Community are committed to the Abuja Targets for Roll Back Malaria in Africa, and this includes improved detection and response to epidemics [1]. To meet these targets countries are expected to detect 60% of malaria epidemics within two weeks of onset, and respond to 60% of epidemics within two weeks of their detection. The countries recognize that to achieve these targets they need improved information on where epidemics are most likely to occur, and ideally some indicatio
Assessing the burden of pregnancy-associated malaria under changing transmission settings
Mario Recker, Menno J Bouma, Paul Bamford, Sunetra Gupta, Andy P Dobson
Malaria Journal , 2009, DOI: 10.1186/1475-2875-8-245
Abstract: Here, by re-examining historical data, it is demonstrated how excess female mortality can be used to evaluate the burden of PAM. A simple mathematical model is then developed to highlight the contrasting signatures of PAM within the endemicity spectrum and to show how PAM is influenced by the intensity and stability of transmission.Both the data and the model show that maternal malaria has a huge impact on the female population. This is particularly pronounced in low-transmission settings during epidemic outbreaks where excess female mortality/morbidity can by far exceed that of a similar endemic setting.The results presented here call for active intervention measures not only in highly endemic regions but also, or in particular, in areas where malaria transmission is low and seasonal.Malaria during pregnancy poses a significant threat to both the mother and unborn child. For the mother, it increases the risk of illness, severe anaemia and death; for the unborn child it increases the risk of intra-uterine growth retardation and low birth weight, spontaneous abortion and stillbirth (reviewed in [1]). Numerous epidemiological studies have highlighted the various aspects of malaria during pregnancy both in highly endemic regions (mostly from sub-Saharan Africa) and in regions where malaria transmission is low and sporadic (mainly from Asia) (see e.g. [1-4]), and it has become clear that the pathology of malaria during pregnancy and its evaluation are highly dependent on the particular epidemiological setting, due to differences in acquired immunity in women reaching child-bearing age.Acquired immunity to Plasmodium falciparum, the most virulent agent of human malaria, is a gradual process by which individuals build up a repertoire of protective immune responses over years of repeated exposure. Although sterilizing immunity might never be attained, people living in malaria endemic areas seem to acquire protection against clinical malaria after a certain period of exposu
Studying Malaria Epidemic for Vulnerability Zones: Multi-Criteria Approach of Geospatial Tools  [PDF]
Firoz Ahmad, Laxmi Goparaju, Abdul Qayum
Journal of Geoscience and Environment Protection (GEP) , 2017, DOI: 10.4236/gep.2017.55003
Abstract: Introduction: Despite serious interventions worldwide, malaria remains a significant cause of global morbidity and mortality. Malaria endemic zones are predominant in the poorest tropical regions of the world, especially in continental Africa and South-Asia. Major Indian population reside in malaria endemic zones which are tribal dominated and inaccessible. Lack of suitable data, reporting and medical facilities in malaria vulnerable regions handicaps the decision makers in taking adequate steps. Natural resources were mapped to establish their possible linkage with malaria incidence and to delineate malaria hotspots using geo-spatial tools. Methods: Remote sensing data along with various ancillary data such as socio-economic (population in general, child population, tribal population, literacy), epidemiology (Malaria API and Pf cases) and environmental parameters (wetness, forest cover, rainfall, aspect, elevation, slope, drainage buffer, and breeding sites) were integrated on GIS platform using a designed weight matrix. Multi criteria evaluation was done to generate hotspot for effective monitoring of malaria incidences. Results: Various thematic layers were utilized for integrated mapping, and the final map depicted 59.1% of the study area is vulnerable to high to very high risk of malaria occurrence. Manoharpur Administrative Block consisted of 89% of its area under high to very high probability of malaria incidence and it needs to be prioritized first for preventing epidemic outbreak. Various village pockets were revealed for prioritizing it for focused intervention of malaria control measures. Conclusions: Geospatial technology can be potentially used to map in the field of vector-borne diseases including malaria. The maps produced enable easy update of information both spatially and temporally provide effortless accessibility of geo-referenced data to the policy makers to produce cost-effective measures for malaria control in the endemic regions.
Genetic Surveillance Detects Both Clonal and Epidemic Transmission of Malaria following Enhanced Intervention in Senegal  [PDF]
Rachel Daniels, Hsiao-Han Chang, Papa Diogoye Séne, Danny C. Park, Daniel E. Neafsey, Stephen F. Schaffner, Elizabeth J. Hamilton, Amanda K. Lukens, Daria Van Tyne, Souleymane Mboup, Pardis C. Sabeti, Daouda Ndiaye, Dyann F. Wirth, Daniel L. Hartl, Sarah K. Volkman
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0060780
Abstract: Using parasite genotyping tools, we screened patients with mild uncomplicated malaria seeking treatment at a clinic in Thiès, Senegal, from 2006 to 2011. We identified a growing frequency of infections caused by genetically identical parasite strains, coincident with increased deployment of malaria control interventions and decreased malaria deaths. Parasite genotypes in some cases persisted clonally across dry seasons. The increase in frequency of genetically identical parasite strains corresponded with decrease in the probability of multiple infections. Further, these observations support evidence of both clonal and epidemic population structures. These data provide the first evidence of a temporal correlation between the appearance of identical parasite types and increased malaria control efforts in Africa, which here included distribution of insecticide treated nets (ITNs), use of rapid diagnostic tests (RDTs) for malaria detection, and deployment of artemisinin combination therapy (ACT). Our results imply that genetic surveillance can be used to evaluate the effectiveness of disease control strategies and assist a rational global malaria eradication campaign.
Contrasting Transmission Dynamics of Co-endemic Plasmodium vivax and P. falciparum: Implications for Malaria Control and Elimination  [PDF]
Rintis Noviyanti?,Farah Coutrier?,Retno A. S. Utami?,Hidayat Trimarsanto?,Yusrifar K. Tirta?,Leily Trianty?,Andreas Kusuma?,Inge Sutanto?,Ayleen Kosasih?,Rita Kusriastuti
PLOS Neglected Tropical Diseases , 2015, DOI: 10.1371/journal.pntd.0003739
Abstract: Background Outside of Africa, P. falciparum and P. vivax usually coexist. In such co-endemic regions, successful malaria control programs have a greater impact on reducing falciparum malaria, resulting in P. vivax becoming the predominant species of infection. Adding to the challenges of elimination, the dormant liver stage complicates efforts to monitor the impact of ongoing interventions against P. vivax. We investigated molecular approaches to inform the respective transmission dynamics of P. falciparum and P. vivax and how these could help to prioritize public health interventions. Methodology/ Principal Findings Genotype data generated at 8 and 9 microsatellite loci were analysed in 168 P. falciparum and 166 P. vivax isolates, respectively, from four co-endemic sites in Indonesia (Bangka, Kalimantan, Sumba and West Timor). Measures of diversity, linkage disequilibrium (LD) and population structure were used to gauge the transmission dynamics of each species in each setting. Marked differences were observed in the diversity and population structure of P. vivax versus P. falciparum. In Bangka, Kalimantan and Timor, P. falciparum diversity was low, and LD patterns were consistent with unstable, epidemic transmission, amenable to targeted intervention. In contrast, P. vivax diversity was higher and transmission appeared more stable. Population differentiation was lower in P. vivax versus P. falciparum, suggesting that the hypnozoite reservoir might play an important role in sustaining local transmission and facilitating the spread of P. vivax infections in different endemic settings. P. vivax polyclonality varied with local endemicity, demonstrating potential utility in informing on transmission intensity in this species. Conclusions/ Significance Molecular approaches can provide important information on malaria transmission that is not readily available from traditional epidemiological measures. Elucidation of the transmission dynamics circulating in a given setting will have a major role in prioritising malaria control strategies, particularly against the relatively neglected non-falciparum species.
An online operational rainfall-monitoring resource for epidemic malaria early warning systems in Africa
Emily Grover-Kopec, Mika Kawano, Robert W Klaver, Benno Blumenthal, Pietro Ceccato, Stephen J Connor
Malaria Journal , 2005, DOI: 10.1186/1475-2875-4-6
Abstract: Rainfall is one of the major factors triggering epidemics in warm semi-arid and desert-fringe areas. Explosive epidemics often occur in these regions after excessive rains and, where these follow periods of drought and poor food security, can be especially severe. Consequently, rainfall monitoring forms one of the essential elements for the development of integrated Malaria Early Warning Systems for sub-Saharan Africa, as outlined by the World Health Organization.The Roll Back Malaria Technical Resource Network on Prevention and Control of Epidemics recommended that a simple indicator of changes in epidemic risk in regions of marginal transmission, consisting primarily of rainfall anomaly maps, could provide immediate benefit to early warning efforts. In response to these recommendations, the Famine Early Warning Systems Network produced maps that combine information about dekadal rainfall anomalies, and epidemic malaria risk, available via their Africa Data Dissemination Service. These maps were later made available in a format that is directly compatible with HealthMapper, the mapping and surveillance software developed by the WHO's Communicable Disease Surveillance and Response Department. A new monitoring interface has recently been developed at the International Research Institute for Climate Prediction (IRI) that enables the user to gain a more contextual perspective of the current rainfall estimates by comparing them to previous seasons and climatological averages. These resources are available at no cost to the user and are updated on a routine basis.It is estimated that more than 110 million Africans live in areas prone to epidemics of malaria. Populations in these areas are infrequently challenged by malaria and, therefore, do not fully develop acquired immunity. As a result, the disease remains life threatening to all age groups. The impact of malaria epidemics could be greatly reduced by timely detection or, ideally, by prediction and prevention through
Sickle cell hemoglobinopathy protection against malaria: is it changing?  [PDF]
Arti Prasad Muley,Jitendra Lakhani, Maulik Parikh
International Journal of Biological and Medical Research , 2011,
Abstract: Sickle cell hemoglobinopathy has a world wide occurrence, although more concentrated in some specific areas and tribes. It has been thought to originate in malaria endemic areas e.g; Africa and central parts of India for protection from malarial parasite. Reports of association of malaria (vivax or falciparum) with sickle cell anemia are available from South Africa but surprisingly rare from other parts of the world. The first detailed report on the importance of malaria as a cause of morbidity and mortality in patients living with SCA was published in January 2010.We, at west coast of India, came across 5 cases of sickle cell anemia (both trait and disease) which were infected with malarial parasites (4 with falciparum and 1 with vivax). All were complicated irrespective of the degree of parasitemia and species of parasite. We report these cases to highlight the severity of malaria in cases of sickle cell hemoglobinopathy ( which is known to have evolved as a protection against malaria) and to emphasise upon the need for detailed research to find out association between SCA and severity of malaria.
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