Research Article: Prospects for Malaria Elimination in Mesoamerica and Hispaniola

Date Published: May 14, 2015

Publisher: Public Library of Science

Author(s): Sócrates Herrera, Sergio Andrés Ochoa-Orozco, Iveth J. González, Lucrecia Peinado, Martha L. Quiñones, Myriam Arévalo-Herrera, David Joseph Diemert.

Abstract: Malaria remains endemic in 21 countries of the American continent with an estimated 427,000 cases per year. Approximately 10% of these occur in the Mesoamerican and Caribbean regions. During the last decade, malaria transmission in Mesoamerica showed a decrease of ~85%; whereas, in the Caribbean region, Hispaniola (comprising the Dominican Republic [DR] and Haiti) presented an overall rise in malaria transmission, primarily due to a steady increase in Haiti, while DR experienced a significant transmission decrease in this period.The significant malaria reduction observed recently in the region prompted the launch of an initiative for Malaria Elimination in Mesoamerica and Hispaniola (EMMIE) with the active involvement of the National Malaria Control Programs (NMCPs) of nine countries, the Regional Coordination Mechanism (RCM) for Mesoamerica, and the Council of Health Ministries of Central America and Dominican Republic (COMISCA). The EMMIE initiative is supported by the Global Fund for Aids, Tuberculosis and Malaria (GFATM) with active participation of multiple partners including Ministries of Health, bilateral and multilateral agencies, as well as research centers. EMMIE’s main goal is to achieve elimination of malaria transmission in the region by 2020. Here we discuss the prospects, challenges, and research needs associated with this initiative that, if successful, could represent a paradigm for other malaria-affected regions.

Partial Text: Despite its global decreasing trend, malaria remains an important public health problem worldwide, affecting mainly developing countries in Africa, Asia, and Latin America (LA). After several decades of steady increase, from about 2000 when ~500 million cases were reported, malaria incidence decreased and, in 2013, an estimated ~198 million clinical malaria cases and ~584,000 deaths were reported [1], representing a global morbidity decrease of >50% and mortality of ~45% [1,2]. Approximately 80% of these cases were caused by Plasmodium falciparum, followed by ~20% P. vivax infections, with a limited number of cases caused by P. malariae, P. ovale, and P. knowlesi [1].

Approximately 120 million people in 21 American countries live at risk of malaria infection within the context of hypoendemic and unstable transmission [1,6,7]. The Amazon basin shows the greatest transmission involving five countries with ~90% of the malaria burden in the continent (Fig 1). P. vivax accounts for ~74% of the cases, P. falciparum for ~26%, and a limited number of cases (~0.1%) are caused by P. malariae [5].

Despite substantial malaria increase in SA between the 1960s and 1990s due to multiple factors, including parasite resistance to chloroquine and sulfadoxine-pyrimethamine [12,14,15], appearance and spreading of DDT resistance [16,17], decentralization of health systems with integration of the vertical malaria control programs, and reduction of resources [8], in the 2000–2012 period, malaria transmission in SA experienced a great overall reduction (80.3%). There were periodic epidemic spikes associated to climate changes caused by “El Niño” Southern Oscillation (ENSO), which mainly affected Colombia, Ecuador, and Peru [13,18], but also countries like Venezuela and Guyana [18–20]. Almost 52% of the malaria cases in the continent are from Brazil, followed by Colombia (12.8%), Venezuela (11.2%), Peru (6.7%), and Guyana (6.7%) [5], indicating that ~90% of the SA malaria cases are from the Amazon basin [13,21] (Fig 1). Guyana and Venezuela are the only countries with recent malaria increases [5,22], with an increasing proportion of P. falciparum cases. Countries such as Surinam and French Guiana have experienced expansion of gold mining accompanied by population migration [23–25]. The remaining 10% is being transmitted in non-Amazonian regions: Andean regions with areas of Peru, Ecuador, and Colombia showing less transmission intensity, mainly in lowlands near the Pacific coast. A project sponsored by the GFTAM to reinforce malaria control activities at countries’ borders (PAMAFRO) [26] significantly reduced the disease burden in these regions generating a positive scenario for elimination efforts. However, the northwestern region of Colombia, in proximity to Panama, is among the most endemic of this country representing a threat for EMMIE.

During the past decade, malaria experienced a remarkable decrease in Mesoamerica, with P. vivax as the predominant species and only small remaining foci of autochthonous P. falciparum transmission. In contrast to the rest of the world, in particular SA, both parasite species are still susceptible to chloroquine [13], which is, therefore, routinely administered in Mesoamerican countries for malaria treatment, except for in Panama where P. falciparum treatment is based on Arthemeter-Lumefantrine [1]. Malaria decreased from ~123,000 cases in 2000 to ~14,798 in 2012, with an epidemic peak occurring in 2005 (Fig 2). Malaria burden has shown a decreasing trend in the Mesoamerican region in the last decade [5]; during this period, the Slide Positivity Rate (SPR) was significantly lower than in the rest of LA (Fig 3).

Malaria was eliminated in most of the Caribbean islands 45 years ago, except for Hispaniola. Since then, only a few imported cases have been reported in the other Caribbean Islands, although an outbreak with >400 P. falciparum cases occurred in Jamaica in 2007, and a prompt reaction resolved it over a four month period [28]. Currently, malaria is only endemic in Hispaniola (composed of Haiti and Dominican Republic [DR]) with almost exclusive transmission of P. falciparum, which remains susceptible to chloroquine, and with An. albimanus as its main vector. Malaria cases increased from 10,871 in 2001 to 26,375 in 2012, with an epidemic peak in 2010 associated with the earthquake in Haiti when ~86,633 P. falciparum cases and two P. vivax were reported [5], although these figures may not be completely reliable due to deficiencies in the malaria information systems. Although a significant reduction was achieved with malaria control interventions to reduce the epidemics associated with the earthquake and the number of autochthonous cases in DR has been decreasing, it may not reach the MDG-6 goal. Malaria in DR has decreased from 3,837 to 952 cases between 2005 and 2012 with a great proportion of cases presumably imported from Haiti [5]. A systematic effort to strengthen the control towards elimination in the island appears timely.

Because of the recent reduction trend in malaria transmission (four out of eight countries are in the pre-elimination phase), as well as the relative degree of development of Mesoamerica and DR, a sub-regional initiative aiming at Elimination of Malaria in Mesoamerica and Hispaniola (EMMIE: Eliminación de Malaria en Mesoamerica y la Isla Española) by 2020 has been recently launched led by the GFATM with support from the governments of participant countries. In June 2013, COMISCA subscribed to the “Declaration for the Elimination of Malaria in Mesoamerica and Hispaniola Island by 2020” and instructed its Executive Secretariat (SE-COMISCA) to implement permanent monitoring [29].

Despite the favorable malaria epidemiological conditions towards elimination efforts in Mesoamerica and great political support, several technical, administrative, and financial challenges are anticipated for EMMIE implementation.

Multiple knowledge gaps are revealed when shifting from malaria control to elimination that underscores the need for a comprehensive research agenda. The Malaria Eradication Research Agenda (MalERA) [48,49] was provided by the RBM Global Malaria Action Plan and the Malaria Elimination Group, under the sponsorship process. At the regional level, PAHO has devoted considerable effort to defining a regional malaria research agenda for the continent [50] considering current malaria elimination initiatives in Mesoamerica. However, research needs would change locally and would require significant involvement of the NMCPs, local academia, as well as external technical support. Knowledge gaps range from social, economic, and anthropological to more biological and basic knowledge questions, from identifying the means to communicate and involve indigenous communities, as well as survey the sensitivity of parasite and mosquito populations, to current anti-malarials and insecticides, to prevalence of genetic traits of the communities that may influence malaria elimination. An assessment of G6PD deficiency in the EMMIE communities would be essential as more people are likely to be treated in an elimination program.

The significant recent progress in Mesoamerica as well as the strengthening of malaria control measures in Hispaniola represent a great opportunity for malaria elimination in the region. The EMMIE initiative’s goal is to bring malaria transmission to zero by 2020. Although an initial seed grant of US$10M to incentivize the work during 2014–2107 is greatly insufficient, it is generating great enthusiasm among governments in the region, which have promised additional funding. However, substantial additional funding is required from donors to secure the estimated US$180 million needed. A broad call to bring together numerous stakeholders is ongoing and a number of external partners have already joined the initiative. Great challenges and knowledge gaps are being faced, but valuable joint work by academic partners resulted in considerable progress in 2014.



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