South America : climate signals and epidemics. Y.Tourre article’s

Spatio-temporal variability of NDVI–precipitation over southernmost South America : possible linkages between climate signals and epidemics

Y M Tourre,
 [1] L Jarlan,
J-P Lacaux,
C H Rotela,
M Lafaye,

Extract of iop publishing website (Published 15 December 2008 )

Climate–environment variability affects the rates of incidence of vector-borne and zoonotic diseases and is possibly
associated with epidemics outbreaks. Over southernmost South America the joint spatio-temporal evolution of
climate–environment is analyzed for the 1982–2004 period. Detailed mapping of normalized difference vegetation
index (NDVI) and rainfall variability are then compared to zones with preliminary epidemiological reports. A
significant quasi-biennial signal (2.2- to 2.4-year periods, or QB) for joint NDVI–rainfall variability is revealed.
From rotated EOFs, dominant NDVI patterns are partitioned according to their lead frequencies : (1) the ‘QB group’
(2.1-to 3-year periods) includes six modes over southern Brazil, Uruguay, northern-central Argentina (two modes),
the southern Paraguay–northern Argentina border, and the Santa Cruz Province ; (2) the QB1 (2.4- to 3-year
+ quasi-quadrennial (QQ) mode over the Misiones Province ; and (3) the QB2 (2.1- to 2.5-year periods) +
+ inter-annual (IA) (3- to 7-year periods) two modes over south-eastern Argentina. Modes within the ‘QB
group’ are positively correlated with global climate signals and SST. The Uruguayan mode is correlated with global
ENSO (8-month lag) whilst the southern Entre-Rios/northern Buenos Aires provinces are correlated with central
equatorial Pacific SSTs (3-month lag). The Santa Cruz (Patagonia) Province is most correlated with the Pacific
South America (PSA) index and SST patterns (3-month lag) along the Antarctica circumpolar current. The spatial
distribution of lead NDVI modes includes the Formosa, Misiones, Chaco and Buenos Aires provinces among
others, known for being prone to vector-borne epidemics such as dengue fever, malaria, leishmaniasis (American
cutaneous leishmaniasis or ACL), hantivirus, chagas and Argentine hemorrhagic fever (AHF). Some provinces also
correspond to regions where lead NDVI PCs’ modes are associated with high-frequency climate signals such as the
quasi-biennial oscillation in northwest Argentina. The joint preliminary results (climate–environment–public health
reports) presented here for the first time are meant : (1) to contribute to a better understanding of
climate–environment–epidemics process-based and modeling studies and (2) to facilitate, in the long run, the
implementation of local and regional health early warning systems (HEWS) over southernmost South America. The
latter is becoming crucial with ever-increasing migration, urban sprawl (re-emergence of dengue fever epidemics
since the late 1990s), all embedded in a climate change context.

Keywords : climate and environment, NDVI, epidemics, southernmost South America

full text

[1METEO-France, Meteopole, 42 Avenue Coriolis, 31057 Toulouse Cedex 1, France and Lamont Doherty Earth Observatory (LDEO), Columbia University, Palisades, NY 10964, USA

[2Centre d’Etudes Spatiales de la Biosphère (CESBIO), 18 avenue Edouard Belin,
F-31401 Toulouse Cedex 4, France

[3Université Paul Sabatier (UPS), Observatoire Midi Pyrénées (OMP), 12 Avenue Edouard Belin, 31400 Toulouse, France

[4Instituto de Altos Estudios Espaciales ‘Mario Gulich’, Comision Nacional de Actividades Espaciales (CONAE), Universidad Nacional de Cordoba, Argentina

[5CNES, DSP/ARP/AV, 18 Avenue Edouard Belin, F-31401 Toulouse Cedex 4, France