Home CHA. Regional Strategic Plan for Malaria in the Americas Nevertheless, there is consensus that Strategies must be of optimum relevance to the realities of the malaria situation in the region and among its member territories. Strategies must be supported by the best available evidence and should be in the best possible alignment with and responsiveness to the specificities in the different levels of work—global, regional, subregional, and national.
Strategies must be designed according to objectives and expected results that are specific, measurable, achievable, relevant, and time-bound. Malaria Infographic. About 3 billion people live in endemic areas where malaria is one of the major health problems. Control measures are largely based on vector eradication programs and clinical treatment, but their efficacy is dramatically reduced by increasing the resistance of vector and parasite. New drugs at low cost are urgently needed.
Unfortunately, although the World Health Organization negotiates with pharmaceutical companies in order to reduce the prices of antimalarial drugs, these remain unattainable for most of the affected populations 2. Therefore new and affordable treatments are a major priority for affected countries. In this context, Methylene blue MB , which has been proven to be active 3, 4, 5 and inexpensive, could be a suitable alternative.
Methylene blue is the oldest and cheapest synthetic drug ever used in antimalarial therapy Figure 1. In Guttmann and Ehrlich published the first report of its antimalarial activity 4.
Two years later, Ferreira 5 recommended the use of MB by oral route in children with malaria. At the beginning of the 20 th century, MB served as structural starting point for the development of 8-aminoquinolines 3, 6, 7 and disappeared thereafter from the antimalarial arsenal. Afterwards, few works on the antimalarial properties of MB have been reported because it was thought to enhance haemolysis in glucosephosphate-deshydrogenase G6PD deficiency 8 and could stain the tissues of MB-treated people 9.
Recently Mandi et al. These observations renewed the interest of MB as a cost-effective alternative in the treatment of malaria. This report presents data on the in vivo antimalarial activity of MB against blood and liver forms of rodent malaria parasites and the in vitro cytotoxicity on BJAB cells, thereby completing other studies published by our research team. Effect on the intraerythrocytic cycle. The classical 4-day suppressive test 14 was conducted with P. Batches of five mices were orally treated with MB at doses of 50, 25, The survival of mice was checked daily and the percentage of parasitized erythrocytes was determined on day 4, by Giemsa-stained thin blood smears from peripheral blood.
The percentage of inhibition of parasitaemia was calculated, and the Effective Dose 50 ED 50 was determined with a linear least square regression analysis. The in vivo activity on the pre-erythrocytic stage was determined according to Peters and Robinson 15 : Batches of three mice were intravenously inoculated with 10 8 sporozoites of P. The suppressive effect was estimated on 48, 72, 96, , , and hours after inoculation by Giemsa-stained thin blood smears inspection.
Animals which showing no signs of infection on day 14 were considered as cured. The CC 50 Cytotoxic Concentration 50 i. A control of viability was carried out in parallel. All chemicals reagents were provided by Sigma-Aldrich.
Regional Strategic Plan for Malaria in the Americas 2006-2010
Radiolabels were provided by PerkinElmer Courtaboeuf, France. Against erythrocytic forms in rodent malaria parasites, MB was more active on P.
The low ED 50 found with P. Permutation tests up to 4, were used to identify the best model. Results were considered to be significant at P value less than 0.
Of 21 countries for which data were analyzed, annual malaria case series were available for all four variables over 53 years from to for 14 countries Table 1. For Argentina, SPR data were not available for Information from Brazil was available for all variables during the entire period with the exception of the year Similarly, the rate was unavailable for Guatemala in and Peru in and Species-specific rates were unavailable for French Guiana in For Haiti, data were available since , and information for all variables was missing for , , and In French Guiana and Guatemala, the trends for these two indicators were widely different and even in different directions.
Specifically, in Guatemala, whereas API was declining significantly, SPR was increasing significantly between and , pointing to a possible decrease in surveillance quality and coverage of diagnosis and treatment during those years. Mexico, El Salvador, and Paraguay were the only countries where the joinpoint years and trend directions for both SPR and API coincided for almost all segments, but different values were obtained for others Table 2.
By , a reversal in the malaria trends was observed; five countries had significantly decreasing API, but it was not accompanied by significant reductions in the SPR. During —, this declining malaria trend was further accentuated; by the end of that decade, 13 countries showed reductions in API, and the number of countries with significantly declining SPR increased from 2 to 7. Malaria continued to decline, and by the middle of —, 12 and 16 countries had significantly decreasing SPR and API, respectively. The change from an increasing or non-significant trend for API to a significantly declining API or joinpoint year was seen in the — period for most countries in the Americas, but in Colombia, Ecuador, Panama, and Suriname, this change was observed in the — period.
In some countries, the significant declining API has not been of constant magnitude; in Belize, the annual rate of reduction declined from In Bolivia, there was a similar change in the rate of decline from The rapid API reduction rates were consequent of the fact that, for the year period under review, both of these countries reported the highest API during —, and the initial rapid decline was from those observed peaks. In contrast, the annual rate of decline increased in Brazil and Guatemala from 2.
A major reversal of malaria trend toward decline was seen in the — period; 13 countries had a significantly declining SPR in , and 7 of them Brazil, Costa Rica, Ecuador, French Guiana, Guatemala, Panama, and Suriname changed from previously increasing or non-significant SPR during — Of note is the significantly declining SPR for over two decades in Mexico and El Salvador, both of which are presently in the pre-elimination phase. Analysis of the P. Joinpoint years for the two species-specific rates were not equal for any of the countries, signifying different species-specific trends for all countries Table 3.
Thereafter, a reversal was seen in subsequent years. PvIR reduced significantly in many countries in the latter half of — and almost all countries 17 by the mid— period. By , one-half of the countries had significantly declining PfIR, and this continued through — This rapid and sustained decline in the whole subregion in the last decade has formed the basis for present regional malaria elimination efforts in these countries.
Even in absolute numbers, the case burden has decreased since the last joinpoint for most countries in the American continents Table 5. Trends presented here are based on reported cases, which are affected by robustness of surveillance systems and quality and coverage of diagnostic services. However, trends for most countries and periods in our study seem to generally reflect the historic incidence of disease. Several factors may be responsible for malaria increases in these years: some specific to countries and others specific to certain periods of time.
In general, malaria increased during the first decade of the eradication efforts in the s in the Americas, probably associated with improved case detection and reporting.
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Malaria spiked in the s as vector resistance to insecticides, primarily dichloro diphenyl trichloroethane DDT , became established in most Central American countries; between and , malaria incidence increased by almost 11 times in Guatemala because of insecticide resistance.
Disruptions in health services during political and social disturbances were responsible for increases in some countries; decrease and cessation of vector control activities by in Nicaragua because of the revolution led to an accompanying increase in malaria.
Change of agricultural practices was a principal reason for the increase in malaria in the s in many Central American countries; switching from growing rice and cotton to African palm and banana was associated with an increase in breeding sites caused by deforestation and associated work-related migration of people, often from malaria-endemic areas. Reduction in malaria started well in the — period and continued throughout — However, some countries had the highest malaria incidence rates of the five decades during the — period, including Belize, Bolivia, Costa Rica, Guyana, Nicaragua, Peru, and Suriname.
Other countries also reported spikes in malaria incidence in the same period.
It has been previously shown that this environmental phenomenon has been associated with malaria epidemics in Colombia, Peru, Venezuela, and Guyana in the s and s. The majority of the countries had simultaneous significant downtrends for both API and SPR during the — period, which can be considered a demonstration of a declining malaria incidence accompanied by consistently functional surveillance.
This is related to increased malaria control and surveillance efforts in most endemic countries, 15 of which received external financial support through Global Fund for AIDS, Tuberculosis and Malaria Global Fund grants during that period. Venezuela, Dominican Republic, and Haiti show an increasing malaria incidence in recent years. In Venezuela, this is accompanied by an increasing proportion of cases caused by P. Adjoining areas of Guyana have been presenting a similar picture in recent years associated with increased gold mining in the Amazon forest areas of these two countries.
This phenomenon has also increased the population at risk of malaria and in most instances, in virgin rainforests with limited access to health clinics. This underlines the shared risk factors of mobile populations living at the high risk associated with gold mining in these two countries as well as Suriname, French Guiana, and adjoining areas of Brazil.
Brazil and Colombia together report more than one-half of the malaria cases in the Americas and have shown efforts in identifying and successfully targeting at-risk populations. However, P. However, additional studies are required for analyzing these associations. Haiti and Dominican Republic, sharing the island of Hispaniola, have exclusively P. A large proportion of cases in Dominican Republic has reportedly been imported from Haiti, leading to an increase in the total case incidence, although the number of autochthonous cases in the country has been declining.
Natural disasters have been associated with increases in malaria incidence on the island; Hurricanes David and Federico led to increase in — and Hurricane George led to an increase in in Dominican Republic. It is likely that this is an artefact, because the increase was mostly from the center department of the country, which was most affected by the earthquake, and the same persons may have been tested more than one time by different relief agencies, leading to duplication of data.
Limited access to diagnosis and treatment and a weak surveillance system increase the uncertainty of observed malaria incidence trends in the country; for example, the SPR reported by the country varied from Mexico, El Salvador, and Costa Rica, three countries in the pre-elimination phase, have had sustained reductions in malaria incidence for two or more recent decades. They do not report autochthonous P. Although Honduras and Nicaragua have been reporting higher proportions of cases caused by P.
All of the Central American countries are preparing to progress toward the pre-elimination and elimination phases.
Malaria in the Americas: Trends from 1959 to 2011
Political support for this goal was evidenced in the form of a recent resolution passed by the ministers of health of the Mesoamerican countries as well as the Dominican Republic and Haiti to eliminate malaria by Argentina and Paraguay, in the southern cone of South America, are also targeted for elimination; they are both presently in the pre-elimination phase with exclusively P. Paraguay reported an outbreak of malaria in , but thereafter, malaria decreased significantly, with only one autochthonous case reported in and none up to week 51 in Overall, funding for malaria control from national sources kept increasing while financing from external sources declined between and with waning interest of donor agencies, largely mirroring the malaria problem as it grew during those years.
However, additional investigation is required to adeptly relate the malaria trend in the American continents to historic trends in malaria financing and coverage of other malaria control interventions. The new funding model of the Global Fund takes the countries' World Bank classification based on the gross domestic product GDP and malaria burden into account.
Thus, many previously eligible countries in the Americas will have less likelihood of receiving external funding.
Malaria in the Americas: Trends from to
Given the fact that 18 of the endemic countries have shown marked decreases in malaria burden and some of these have also intimated interest in eliminating the disease, it is imperative that national resources presently available continue to be destined to further malaria reduction. Also, additional resources should be made available to ensure functional surveillance systems in areas where elimination has been achieved to prevent reintroduction.
Failure to adequately address funding shortages in years ahead could lead to increases in malaria, which has been previously seen. In a article, White 45 proposed that increased P. Such a temporal increase pattern was seen in Brazil and Venezuela during the — period and Ecuador during — However, such an association can be better ascertained with data collected at weekly or monthly intervals and at the level of localities or foci. Associations like these will require more detailed analysis to better establish this relationship, because the data presented here do not so permit.
Although Chaparro and Padillo 46 used joinpoint regression analysis for malaria deaths in Colombia, this methodology has mostly been used for chronic diseases, such as cancer, which unlike malaria, are not prone to rapid changes in annual incidence rates. Furthermore, the innate variability in reporting of incidence data because of social, economic, and programmatic reasons also limits interpretation of trends.
However, use of joinpoint regression in this study has provided satisfactory results. Decreased cases were reported in and in Guatemala owing to temporary weakening of information systems as a result of decentralization; however, this artefact did not affect the declining trend since the late s that was evidenced by joinpoint methodology. However, large and abrupt variation in cases, which was seen in some countries in the s and s, resulted in non-significant trends, signifying possible inadequate quality of data.
Although this study used country-level data, malaria incidence rates could both increase and decrease at the state or district level within a country in the same year or period. State- or district-level analyses would, thus, present a better understanding of underlying patterns of malaria incidence for use in decision-making at the subnational and local levels, especially when pursuing the goal of malaria elimination.
API depends on the definition of the population at risk; the population of the whole country is not accurate for calculating API, because it underestimates the incidence. SPR is conservative, because it measures incidence of malaria in only suspected or tested cases, which are always fewer than the total population at risk. Although both the definition of a suspected case and the coverage of diagnosis impact SPR, it has been proven to be a reliable indicator for measurement of malaria incidence trends.
This is well-observed between and in Guatemala, where declining API would give an impression of decreasing malaria, although increasing SPR points to the problems of decreases in diagnosis and treatment coverage and associated surveillance quality. National surveillance systems and coverage of the national malaria programs have improved over the past 50 years in the endemic countries of the Americas. Presently, all countries, except Haiti, have nominal reporting systems implemented completely or partially throughout the country.
Laboratory-confirmed cases have been used in this study; improvement in the coverage and quality of diagnostic services over the years is, thus, a limiting factor in interpreting results.
Related Regional Strategic Plan for Malaria in the Americas 2006-2010
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