Climatic fluctuations and malaria transmission dynamics, prior to elimination, in Guna Yala, República de Panamá

Abstract

BackgroundMalaria has historically been entrenched in indigenous populations of the República de Panamá. This scenario occurs despite the fact that successful methods for malaria elimination were developed during the creation of the Panamá Canal. Today, most malaria cases in the República de Panamá affect the Gunas, an indigenous group, which mainly live in autonomous regions of eastern Panamá. Over recent decades several malaria outbreaks have affected the Gunas, and one hypothesis is that such outbreaks could have been exacerbated by climate change, especially by anomalous weather patterns driven by the EL Niño Southern Oscillation (ENSO).ResultsMonthly malaria cases in Guna Yala (1998–2016) were autocorrelated up to 2 months of lag, likely reflecting parasite transmission cycles between humans and mosquitoes, and cyclically for periods of 4 months that might reflect relapses of Plasmodium vivax, the dominant malaria parasite transmitted in Panamá. Moreover, malaria case number was positively associated (P < 0.05) with rainfall (7 months of lag), and negatively with the El Niño 4 index (15 months of lag) and the Normalized Difference Vegetation Index, NDVI (8 months of lag), the sign and magnitude of these associations likely related to the impacts of weather patterns and vegetation on the ecology of Anopheles albimanus, the main malaria vector in Guna Yala. Interannual cycles, of approximately 4-year periods, in monthly malaria case numbers were associated with the El Niño 4 index, a climatic index associated with weather and vegetation dynamics in Guna Yala at seasonal and interannual time scales.ConclusionThe results showed that ENSO, rainfall and NDVI were associated with the number of malaria cases in Guna Yala during the study period. These results highlight the vulnerability of Guna populations to malaria, an infection sensitive to climate change, and call for further studies about weather impacts on malaria vector ecology, as well as the association of malaria vectors with Gunas paying attention to their socio-economic conditions of poverty and cultural differences as an ethnic minority.Electronic supplementary materialThe online version of this article (10.1186/s12936-018-2235-3) contains supplementary material, which is available to authorized users.

Variabilidade dos casos de malária e sua relação com a precipitação e nível d’água dos rios no Estado do Amazonas, Brasil

“…Coherence and wavelet phase analysis shows that local environmental conditions play an important role in the vector's seasonal cycle 41 . Consistent with the findings by Hurtado et al 42 , the relations between the variables indicated a strong annual pattern, in addition to significant coherences on the scale of variability less than one year and on the biennial scale. According to Chowell et al 43 , a strong annual pattern can be followed by biennial cycles, but differing by region and by type of malaria.…”

“…The malaria vector is susceptible to meteorological changes, which directly affect the mosquito's life cycle 10 . Information on the potential impact of climatic factors on malaria incidence can be useful for orienting disease prevention programs, aimed at the ultimate elimination of the disease 42 .…”

“…Coherence and wavelet phase analysis has become an increasingly useful and significant tool for interpreting natural phenomena in different fields of study 32,41,42,43 . The technique provides a robust mathematical base that encourages scientific research aimed at analyzing physical signs with complex variabilities.…”

Long-term transmission patterns and public health policies leading to malaria elimination in Panamá

“…Here, evidence about ENSO impacts on malaria transmission dynamics in Panamá was added. Previously, it has been described that malaria transmission in the main endemic regions of Panamá, Comarca Guna Yala and Comarca Guna de Madugandi, peaks follow ENSO oscillations [10,78], and are probably associated with increases in vector abundance. Understanding how and when ENSO impacts malaria transmission in a speci c country and, more generally in a region like Mesoamerica, can be useful for preparing to timely deploy malaria control activities in Panamá.…”

Long-term Transmission Patterns and Public Health Policies Leading to Malaria Elimination in Panamá

“…Indeed, many migrants are from countries where drug resistant strains circulate, a fact that continuously challenges the national malaria program treatment policies [18]. In fact, recent P. falciparum outbreaks in areas where malaria transmission had been previously interrupted have been linked to migratory events across the Panamanian-Colombian border [9,[54][55][56]76]. During this period (2000-2019) a significant and increasing proportion of the P. falciparum total cases were imported, mainly from Colombia (Additional file 3 and 4).…”