American cutaneous leishmaniasis cases in the metropolitan region of Manaus, Brazil: association with climate variables over time

Abstract

A temporal series of the normalized difference vegetation index (NDVI) and other environmental parameters covering the years 2002-2009 was used for the study of the potential association between the climate and the number of cases of American cutaneous leishmaniasis (CL) in Manaus Metropolitan Region (MMR), State of Amazonas, Brazil. The results show that CL has a marked seasonality and a strong linkage with local climate conditions. Dry and warm conditions favor the vector, while the maximum number of CL cases occurs during the following wet season. This has a clear relation to the El Niño/La Niña Southern Oscillation (ENSO) and the results presented here show that uncharacteristic dry conditions in the MMR follow El Niño after a lag period of 3 months, while wet conditions follow La Niña, again after a lag period of 3 months. El Niño brings dry conditions with warming of the land surface leading to increased growth of trees and bushes as indicated by rising NDVI values, eventually producing increased numbers of CL cases, with a peak of new cases occurring 4 to 5 months later. La Niña, on the other hand, produces wet and cool weather, which is less favorable for the leishmaniasis vector and therefore results in comparatively lower number of CL cases. Since these seasonal climate changes affect the dynamics of the CL vector, and thus the number of CL cases, a close watch of the ENSO phenomenon and the weather type it brings should be useful for monitoring and control of CL in the MMR.

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 Ferreira de Souza et al 41 , the biennial scale of ENOS is the principal phenomenon that modulates climatic variability in Amazonia, as reflected mainly by the rainfall anomalies. In the tropics, El Niño/La Niña heavily modulate the interannual changes in the predominant environmental variables.…”

“…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.…”

Effect of temperature, rainfall and relative density of rodent reservoir hosts on zoonotic cutaneous leishmaniasis incidence in Central Tunisia

“…Cutaneous leishmaniasis in Brazil [27] has a marked seasonality and is linked with dry and warm conditions of the following season, which favor the vectors and fly development.…”

An investigation of the effects of environmental and ecologic factors on cutaneous leishmaniasis in the old world: a systematic review study

“…According to the report published by the World Health Organization (WHO) in 2019, the annual incidence of leishmaniasis has been estimated to range from 700,000 to 1.2 million in the world [4,5]. It is estimated that the incidence of leishmaniasis is more than 12 million cases worldwide, and 1.5-2 million new cases are added to this rate annually, 75% of which are of cutaneous forms [6]. CL is hard to treat because no vaccine is yet available [3].…”