Transcript of INTRODUCTIONINTRODUCTION METHODSMETHODS PRELIMINARY RESULTS CONCLUSIONSCONCLUSIONS...
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- INTRODUCTIONINTRODUCTION METHODSMETHODS PRELIMINARY RESULTS
CONCLUSIONSCONCLUSIONS REFERENCESREFERENCES
ACKNOWLEDGMENTSACKNOWLEDGMENTS CLIMATE VARIABILITY AND ITS IMPACT
ON DENGUE AND MALARIA IN MEXICO Hurtado-Daz M 1, Riojas-Rodrguez H
1, Rothenberg SJ 1, Cifuentes-Garca E 1, Gomez-Dants H 2 1 National
Institute of Public Health, 2 Mexican Institute of Social Security
Table 1 Crude association between climate variables and dengue
cases (ln) Veracruz Port and San Andrs Tuxtla, Veracruz Variable
VeracruzSan Andrs Tuxtla Coefficientp valueCoefficientp value
Precipitation20.040.00160.07 Precipitation (1 month
lag)0.00480.00010.020.03 Mixed index0.0740.622 ----- Mixed index (3
months lag)0.2 ----- El Nio 3-0.230.020.060.7 El Nio 3 (3 months
lag)0.170.10.00020.7 Table 2 Crude association between climate
variables and mlaria cases (ln) Pantelh, Chiapas
VariableCoefficientp value Pluvial Precipitation0.00180.073
Precipitation (1 month lag) 0.00150.12 El Nio 3-0.040.56 El Nio
Index, Pluvial Precipitation and Dengue Cases Veracruz 1995-2002
This work was partially granted by Inter-American Institute for
Global Change Research. We would like to give thanks also to the
personnel of Secretary of Health in Veracruz and Chiapas for its
cooperation. Malaria cases, Precipitation and ENSO Index Suchiate
1998-2002 Malaria cases, Precipitation and ENSO Index Tapachula
1998-2000 Cases of Dengue and Precipitation by Month Veracruz
1995-2002 There is evidence that annual and decennial climate
variation has a direct influence on vector-borne parasitic
diseases. 1 2 3 4 5 In Mexico, exist papers on the influence of
climate factors; 6 7 8 9 10 however no papers were found on climate
variability and its influence on health. In this project we are
going to examine the relation between climatic variables
(temperature and precipitation), El Nio Southern Oscillation (ENSO)
indexes and incidence of malaria and dengue in Mexico, to obtain
the methodology for analyzing the complex relations between climate
factors and human diseases. We selected the states of Veracruz
(Veracruz Port and San Andres Tuxtla) for dengue and Chiapas
(Pantelh and Suchiate) for malaria, based on the number of cases.
To construct the databases, we request from the surveillance system
on vector borne diseases, the number of monthly cases of dengue and
malaria by municipality; and from meteorological stations near to
municipalities of study, monthly data of temperature and
precipitation. We used exploratory, univariated and bivariated
analysis (cross correlations) to observe possible links between
diseases, climatic variables and ENSO. To explore the variables
that explain the variation in the number of cases, we created a
linear regression model taking the natural logarithm of cases per
month as the dependent variable In Veracruz, 3939 cases occurred in
a period of 91 months (1995-2002. There were important spikes in
September of 1996 (663 cases) and October of 1997 (508 cases). We
found a significant association (p < 0.05) between number of
cases of dengue and precipitation of the previous month; and the
number of cases of dengue with the ENSO variables, although the
coefficient is positive, it is not significant. In San Andrs Tuxtla
we have been able to establish the association between
precipitation and the increase of cases. This occurs annually with
peaks in certain months that are potentially associated with the
presence of ENSO, as we have observed this trend. Malarias data in
Pantelh were from 1990 to 1998. There were 785 cases, with a mean
rate of 51.6 per 100,000 inhabitants. The mean number of cases per
month is 7.2 with a maximum of 42. The rate shows a diminishing
trend during the period and has two peaks in June 1991 and July
1998. We do not see any relationship with the different ENSO
indexes. In the municipality of Tapachula 2396 cases of malaria
were recorded during the period 1998- 2000. The average number of
cases per month was 47 and the average rate was 17.3 per 100
thousand inhabitants. The highest number of cases occurred in June,
1988 (444 cases). We already collected climatic and health data at
the community level with weekly frequency. We also compiled data
from the year 2002-2003, related to the most recent El Nio event,
in order to have two events in our data series and draw inferences
from such series. The statistical methods that we have used are
relatively simple, but at this time we are using autoregressive
integrated moving average (ARIMA) models to analyze the data with
greater precision. These are preliminary results and we are
incorporating in the this stage of the analysis variables of
migration, social vulnerability and data from vector control
program, to know the effect that has the climate variability in the
incidence of these diseases. 1 Bouma, MJ, Dye C., 1997. Cycles of
Malaria associated with El Nio in Venezuela. JAMA, 178 (21):
1772-1774. 2 Bouma, MP., Poveda, GR, Chavasse D, Quiones M, Cox J,
Patz J. Predicting high-risk years for malaria in Colombia using
parameters of El Nio Southern Oscillation. Tro. Med. Int Health
1997 Dec; 2 (12):1122-7 3 Snchez Tarrago N. (editor) El fenmeno
climatolgico El Nio y sus efectos en la salud. Reporte tcnico de
vigilancianidad de anlisis y tendencias en salud, Ministerio de
Salud Pblica, La Habana Cuba, Vol. 3., no. 3, April 27, 1998 ISSN
1028-4362. 4
http://www.infomed.sld.cu/instituciones/uats/uats/RTV/rtv0398.htm 5
Proveda GJ. Evidencias de la asociacin entre brotes epidmicos de
malaria en Colombia y el fenmeno El Nio-Oscilacin Sur. Revista de
la Academia Colombiana de Ciencias Exactas, Fsicas y Naturales ISSN
0370-3908, Vol. XXI (81) pp. 409-419, November 1997. 6 Rodrguez MH,
Gonzales-Cern L., Hernndez JE, ENTEL JA, Villareal C. Kain KC,
Wirtz RA, Different prevalences of plasmodium vivax phenotypes
VK210 and VK 247 associated with the distribution of Anopheles
albimanus and Anopheles pseudopunctipennis in Mexico. Am J. Trop
Med Hyg 2000, Jan; 62 (1): 122-7 7 Herrera-Basto E, Prevost DR,
Zarate ML, Silva JL, Seplveda Amor J. First reported outbreak of
classical dengue fever at 1,700 meters above sea level in Guerrero
State, Mexico Jun 1988. Am J. Trop Med Hyg 1992 Jun; 46 (6):
649-53. 8 Rodrguez AD, Rodrguez MH, Hernndez JE, Dister SW, Beck
LR, Rejmankova E, Roberts DR. Landscape surrounding human
settlements and Anopheles albimanus (Diptera: Culicidae) abundance
in Southern Chiapas, Mexico. J. Med Entomol 1996, 33 (1): 39-48. 9
Fernndez-Salas I, Roberts DR. Rodrguez MH, Marina-Fernndez CF
Fernndez-Salas. Bionomics of larval populations of Anopheles
pseudopunctipennis in the Tapachula foothills area, southern
Mexico. J. Am Most Control Assoc 1994 Dec; 10 (4): 477-86. 10
Koopman JS, Prevots DR, Vca marin MA et al. Determinants and
predictors of dengue infection in Mexico. Am J Epidemiol 1991 Jun
1; 133 (11): 1168-78 Months Malaria cases Pluvial Precipitation
Mixed Index January 1998 December 2003