Malaria control in an agro-industrial settlement of Rondônia (Western Amazon region, Brazil)

Community-based approaches for malaria case management in remote communities in the Brazilian Amazon

INTRODUCTION

Malaria case management is a pivotal intervention in malaria elimination. However, many remote areas in Brazil still lack access to basic health services. This study describes a community-based approach (CBA) for malaria case management in the large remote area of the Jaú National Park (JNP), Amazonas, Brazil.

METHODS

In 2001, a general health CBA was initiated with a motor group (MG); a participative community health diagnosis (PCHD) was subsequently implemented between 2001 and 2005. In 2006, a CBA for malaria case management started with an expanded MG including all sectors with a stake in malaria control, from the local residents to the federal government. In 2008, community microscopists were selected and trained to diagnose hemoparasites. A full malaria strategy was implemented in 2009 with subsequent quality control follow-up.

RESULTS

Two educational materials were co-created with local communities. The MG identified malaria as a major health problem and the malaria MG planned the control activities. Ten communities selected a resident to become malaria microscopists, and ten solar-operated health centers were built. The number of slide readings increased from 923 in 2006 to 1,900 in 2009, while malaria infections decreased from 354 cases in 2005 to 20 cases in 2015. The excess time (≥ 48 hours) between first symptoms and diagnosis/treatment decreased from 68.9% of cases in 2005 to 14.3% in 2010.

CONCLUSIONS

While many factors were likely involved in the reduction of malaria transmission in the JNP, the CBA played an important role in the sustained success of the initiative.

A historical perspective on malaria control in Brazil

Malaria has always been an important public health problem in Brazil. The early history of Brazilian malaria and its control was powered by colonisation by Europeans and the forced relocation of Africans as slaves. Internal migration brought malaria to many regions in Brazil where, given suitable Anopheles mosquito vectors, it thrived. Almost from the start, officials recognised the problem malaria presented to economic development, but early control efforts were hampered by still developing public health control and ignorance of the underlying biology and ecology of malaria. Multiple regional and national malaria control efforts have been attempted with varying success. At present, the Amazon Basin accounts for 99% of Brazil's reported malaria cases with regional increases in incidence often associated with large scale public works or migration. Here, we provide an exhaustive summary of primary literature in English, Spanish and Portuguese regarding Brazilian malaria control. Our goal was not to interpret the history of Brazilian malaria control from a particular political or theoretical perspective, but rather to provide a straightforward, chronological narrative of the events that have transpired in Brazil over the past 200 years and identify common themes.

Epidemiology of Malaria in Latin America and the Caribbean from 1990 to 2009: Systematic Review and Meta-Analysis

OBJECTIVE

The objective of this study was to evaluate the burden of malaria in Latin America and the Caribbean countries through a systematic review and meta-analysis of published literature, gray literature, and information from countries' public health authorities for the period 1990 to 2009.

METHODS

The random-effects meta-analysis of the prospective studies, carried out in very highly endemic areas, showed an annual incidence rate of 409.0 malaria episodes/1000 person-years (95% confidence interval [CI] 263.1-554.9), considering all ages, which was 40-fold the one estimated from areas with passive surveillance only.

RESULTS

Overall, the most prevalent species was Plasmodium vivax (77.5%; 95% CI 75.6-79.4) followed by Plasmodium falciparum (20.8%; 95% CI 19.0-22.6) and Plasmodium malariae (0.08%; 95% CI 0.07-0.010). Data from regional ministries of health yielded an estimated pooled crude annual mortality rate of 6 deaths/100,000 people, mainly associated with P. falciparum.

CONCLUSION

This study represents the first systematic review of the burden of malaria in Latin America and the Caribbean, with data from 21 countries.

Effectiveness of community health workers in Brazil: a systematic review

The objective of this study is to assess the effectiveness of community health workers (CHWs) in Brazil. This systematic review included all studies that sought to assess interventions involving CHWs. Despite the low quality of evidence for most outcomes, analysis of the 23 publications included often found benefit for CHW intervention, best documented for frequency of child weighing, prevalence of breast-feeding, and delayed introduction of bottle-feeding. These findings and the current major role CHWs play in Brazil suggest that clarifying the benefit of CHW actions across a broad range of health care interventions should be a major research priority.

Epidemiological profile of malaria in the state of Tocantins, Brazil, from 2003 to 2008

This study describes the epidemiological profile of malaria in the State of Tocantins, in the period 2003-2008, investigates the association between the frequency of malaria and population growth, classifies the cases by 'autochthonous' and 'imported', reports the indices of the disease and analyses the distribution of the cases by Plasmodium species, age and gender. The retrospective study was based on secondary data, stored in SIVEP-malaria and analyzed using the software Epi-Info 3.5.1. and Bioestat 5.0. 19,004 samples were investigated for malaria, 19% of them were positive, 73.32% with Plasmodium vivax, 21.80% with Plasmodium falciparum, 4.79% with mixed infections and only 0.08% with Plasmodium malariae. Male individuals accounted for 76.95% and predominated in all years and age groups, especially in the 15 to 49 years old group. From the overall cases, 34.27% were autochthonous and 65.73% were imported (χ2 = 356.8, p = 0.0001). The frequency of malaria decreased significantly during the entire series (rp = 0.96, p = 0.002) and the number of municipalities with autochthonous transmission also diminished. It was found that malaria is predominantly imported, related to land activities, which confirms the need for effective measures to maintain vigilance throughout the state and enhance educational activities in order to guide the population towards early treatment-seeking.

Análise espacial e determinação de áreas prioritárias para o controle da malária, no Estado no Tocantins, 2003-2008

INTRODUÇÃO: No Tocantins, a malária apresenta comportamento diferenciado entre as microrregiões, com predominância dos casos importados. Este estudo descreve a análise espacial da malária no estado, no período de 2003 a 2008, buscando identificar nas microrregiões a incidência de casos autóctones e importados, bem como a procedência destes últimos. MÉTODOS: Trata-se de um estudo retrospectivo, pautado em dados secundários, que teve como fonte de dados o Sistema de Informações de Vigilância Epidemiológica - Malária (SIVEP-Malária), analisados através dos softwares estatísticos Epi Info versão 3.5.1. e Bioestat versão 5.0. RESULTADOS: Constatou-se que a malária não teve distribuição homogênea em todos os municípios. A área de maior prioridade agregou municípios localizados nas microrregiões oeste do estado, fronteira com o Pará, onde também se concentram o maior número de casos autóctones. A associação entre os casos autóctones e importados e as espécies de Plasmodium mostrou uma diferença estatisticamente significativa (G = 54,25; p < 0,0001). Das oito microrregiões, Miracema do Tocantins, Araguaína e Bico do Papagaio agruparam 75,8% dos casos, e nessas, onze municípios se sobressaíram. Quanto à procedência, o Estado do Pará apresentou ampla distribuição com 85,5% do total, seguido por Guiana Francesa com 7,4%. CONCLUSÕES: Os resultados demonstraram a predominância dos casos importados e a diferença entre os municípios e microrregiões, apontando pela influencia de estados vizinhos na determinação das áreas de maior risco. Esses dados são importantes, pois contribuem para orientação e direcionamento das políticas públicas para o agravo no Tocantins.

The dynamics of transmission and spatial distribution of malaria in riverside areas of Porto Velho, Rondônia, in the Amazon region of Brazil

The study area in Rondônia was the site of extensive malaria epidemic outbreaks in the 19(th) and 20(th) centuries related to environmental impacts, with large immigration flows. The present work analyzes the transmission dynamics of malaria in these areas to propose measures for avoiding epidemic outbreaks due to the construction of two Hydroelectric Power Plants. A population based baseline demographic census and a malaria prevalence follow up were performed in two river side localities in the suburbs of Porto Velho city and in its rural vicinity. The quantification and nature of malaria parasites in clinical patients and asymptomatic parasite carriers were performed using microscopic and Real Time PCR methodologies. Anopheles densities and their seasonal variation were done by monthly captures for defining HBR (hourly biting rate) values.

MAIN RESULTS

(i) malaria among residents show the riverside profile, with population at risk represented by children and young adults; (ii) asymptomatic vivax and falciparum malaria parasite carriers correspond to around 15% of adults living in the area; (iii) vivax malaria relapses were responsible for 30% of clinical cases; (iv) malaria risk for the residents was evaluated as 20-25% for vivax and 5-7% for falciparum malaria; (v) anopheline densities shown outdoors HBR values 5 to 10 fold higher than indoors and reach 10.000 bites/person/year; (vi) very high incidence observed in one of the surveyed localities was explained by a micro epidemic outbreak affecting visitors and temporary residents. Temporary residents living in tents or shacks are accessible to outdoors transmission. Seasonal fishermen were the main group at risk in the study and were responsible for a 2.6 fold increase in the malaria incidence in the locality. This situation illustrates the danger of extensive epidemic outbreaks when thousands of workers and secondary immigrant population will arrive attracted by opportunities opened by the Hydroelectric Power Plants constructions.

Malária e aspectos hematológicos em moradores da área de influência dos futuros reservatórios das hidrelétricas de Santo Antônio e Jirau, Rondônia, Brasil

Em Rondônia, prevê-se a construção de mais duas usinas hidrelétricas (UHE) no rio Madeira, a montante da cidade de Porto Velho, Rondônia, Brasil (de Santo Antônio e Jirau). O objetivo deste trabalho foi analisar a prevalência da malária antes do início da implantação das obras civis e fazer considerações sobre os impactos da doença com o ingresso de milhares de trabalhadores e agregados atraídos pelas oportunidades de emprego e comércio. Os resultados obtidos mostram que a malária se faz presente em toda região, em variados graus de prevalência. Além disso, a existência de potenciais portadores assintomáticos de malária entre a população nativa pode ter relevância epidemiológica e deve ser considerada nos programas de controle da malária, vinda tanto das autoridades públicas quanto das empresas responsáveis pela instalação das UHE, visando o diagnóstico e tratamento precoce, controle vetorial, abastecimento de água e aplicação de infra-estrutura nos centros urbanos.

[Socioenvironmental factors associated with the spatial distribution of malaria in the Vale do Amanhecer settlement, Municipality of Juruena, State of Mato Grosso, 2005]

Malaria is a disease with focal distribution. In Brazil, settlement and gold mining areas in the Legal Amazon region present a great concentration of cases. This paper analyzes the spatial distribution of malaria cases taking into consideration environmental and social factors in the Vale do Amanhecer settlement in the municipality of Juruena, Mato Grosso, Brazil. In 2005, 359 autochthonous cases were notified in the settlement. Using the Kernel method, areas of greater and lesser intensities of case numbers were identified. The areas of greater intensity presented 290 cases and those of lesser intensity, 64 cases. The intensity of distribution varied within the settlement, thus indicating areas of great intensity of cases favoring transmission, like gold mining areas. Therefore, although the settlement was considered to be the main focus for malaria, there were specific factors within it that, once identified, could contribute towards the disease control.

Urban malaria in the Brazilian Western Amazon Region I: high prevalence of asymptomatic carriers in an urban riverside district is associated with a high level of clinical malaria

Cross sectional studies on malaria prevalence was performed in 2001, 2002, and 2004 in Vila Candelária, an urban riverside area of Porto Velho, Rondônia, in the Brazilian Western Amazon, followed by longitudinal surveys on malaria incidence. Vila Candelária is a working class district, provided with electricity, water supply, and basic sanitation. Previous preliminary surveys indicated high malaria incidence in this community. At the end of year 2000 regular diagnostic and treatment measures for malaria were introduced, with active search of febrile cases among residents. Despite of both rapid treatment of cases and relative good sanitary and housing conditions, the malaria incidence persisted at high levels during the following years with an annual parasite index of 150 to 300/1000 inhabitants. Parasite surveys in 2001, 2002, and 2004 achieved through microscopy and polymerase chain reaction to diagnose malaria showed a constant high prevalence of asymptomatic carriers for both Plasmodium falciparum and P. vivax parasites. It was concluded that asymptomatic carriers represent an important reservoirs of parasites and that the carriers might contribute to maintaining the high level of transmission. Comparing our findings to similar geo-demographic situations found in other important urban communities of the Brazilian Amazon, we propose that asymptomatic carriers could explain malaria's outbreaks like the one recently observed in Manaus.

[Epidemiological trends of malaria in the State of Mato Grosso, from 1980 to 2003]

The temporal and spatial evolution of malaria in Mato Grosso was determined in periods from 1980-1985, 1986-1991, 1992-1997 and 1998-2003 and distributed by homogeneous microregion. The annual parasitic index of the state rose until 1992 and then diminished to 1.9 cases/1,000 inhabitants in 2003, the ratio of mortality and the lethality rate were greater in the 1980s. Of the 22 microregions, 13 presented an API inferior to 10 cases/1,000 inhabitants in all periods. Cases were concentrated in the microregions of Colíder, Alta Floresta, Aripuanã and Alto Guaporé. In 2003, only the microregion of Aripuanã continued to present an API superior to 50 cases/1,000 inhabitants. The microregions of Colíder, in 1983, 1985 to 1988 and 1990 and Alta Floresta, in 1991 presented deaths over 50/100,000 inhabitants, mainly in males aged 20-49 years. The distribution of the disease in microregions showed that malaria is predominantly found in concentrated sites.

Aggressive active case detection: a malaria control strategy based on the Brazilian model

Since 1996, the Brazilian Ministry of Health has adopted a malaria control strategy known as aggressive active case detection (AACD) in which most or all members of every community are tested and treated for malaria on a monthly basis. The strategy attempts to identify and treat cases of asymptomatic malaria, which, if untreated, continue to transmit the infection. Malaria remains uncontrolled because almost all health care systems in the world rely on passive case detection: the treatment of only symptomatic cases of malaria. Research has shown conclusively that asymptomatic cases exist in any population where malaria transmission is stable and incidence is high: therefore passive case detection simply will not succeed in breaking the cycle of transmission. Numerous case studies show that malaria has been successfully controlled on a regional or national level by mass blood surveys. AACD is an effective malaria control strategy if used in conjunction with other methods, especially when (1) an effective treatment exists, (2) influx of potential carriers of the infection can be monitored, and (3) people are inclined to cooperate with monthly blood testing. AACD requires access to rapid diagnostic tests (RDTs), microscopy supplies, extensive human resources, and prompt, affordable, and effective treatment. AACD is compared to PCD in terms of clinical efficacy and cost effectiveness in a case study of malaria in the Brazilian Yanomami Indians. Where it is feasible, AACD could drastically reduce the incidence of malaria and should be an integral part of the World Health Organization's Roll Back Malaria strategy.

Seasonal malaria transmission and variation of anopheline density in two distinct endemic areas in Brazilian Amazonia

Studies on seasonal anopheline fauna variation were performed in two distinct settlements in the State of Rondônia, Brazil: one at the Madeira River banks (Portuchuelo) with stable native Amazonian population; the other at an inland lumber-extracting farm (Urupá) in dry land, in which adults are mostly migrants. During a 6-yr period (1994-2000), 8,638 adult anophelines were collected: 2,684 in Urupá and 5,954 in Portuchuelo. Anopheles darlingi represented >95% of total mosquitoes caught. Dissection of 4,424 A. darlingi females yielded a very low sporozoite infection index below 0.1%. Oocysts were found in both localities in approximately 0.1% of dissected mosquitoes. Determination of the hour biting rates disclosed seasonal variations in both localities. However, in Portuchuelo, mosquito density peaked at the acme of the rainy season, whereas at Urupá it peaked in the dry season. The increase in mosquito density and incidence of malaria cases were coincident. The high mosquito densities observed in the riverine settlement of Portochuelo sector B, which permits evaluation in > 10,000 mosquitoes' bites/person/year, could explain, in spite of the low mosquito's infection index, the previously described development of natural immunity in the local population that is not observed in the dry land agroindustrial settlement of Urupá.