Annex G: Geographic Information of the Project Area


(Report of the PDF-B phase of the GIS group of the Special Program for Health Analysis – SHA/PAHO in collaboration with the Division of Health and Environment)


Introduction


As a part of the preparation phase (PDF-B) for the project "Comprehensive Action Program to Prevent Reintroduction of DDT for Malaria Control in Mexico and Central America", the prototype of a Geographic Information System (GIS) was developed in order to facilitate the regional analysis of health and environmental problems. This Annex shows some of the techniques utilized to generate interactive thematic maps with preliminary results on the geographical distribution of malaria in Mexico and Central America, as well as the strategies that have been used for malaria control in the participating countries. Examples on the application of various methods of spatial analysis were incorporated in the GIS for the sake of identifying spatial standards in the distribution of malaria control and the use of pesticides.


The main objective of the GIS application in this Project is to compile, standardize and map data related to the use of DDT and newly introduced pesticides in Mexico and Central America, and include geo-referenced information on malaria control, positive cases of malaria and population at risk, distribution of vectors and interventions of control, environmental and ecological factors, and the distribution of the health system.





Demonstration of thematic maps in the area of the project



Map 1. Project Participating Countries: each geographical unit has an active band with different documents and files, as it is the case of the text in Word of the reports per country on malaria control in the region. An ArcView program or "Script" was already personalized in order to generate active bands to documents in PDF format, and programs to link the objects to different image files or videotapes.




Map 2. Annual Parasite Index (API): the background color represents the percentage of positive malaria cases in relation to the population at risk. The graphics show the type of parasite (Plasmodium vivax, P. falciparum, P. malariae, or P. ovale) in each country.




Map 3. DDT application from 1957 to 1997: This map is the result of the standardization of a regional historical database prepared by OPS (HCP, HEP, and SHA), and it shows series of 40 years with indicators of the incidence of malaria and use of pesticides for its control with relation to the total of the Latin American countries. In particular, this map shows the cyclic variations by decade and gradual reduction in the use of pesticides.















Map 4. Total tons of pesticides

The background color represents the amount of pesticides used and the graphics represent the type of pesticides used (DDT, organophosphates, carbamates, dieldrin, others).






Map 5. Amount per capita of pesticides used for malaria control in Central America. Higher concentrations of pesticides were used for malaria control in Nicaragua and Panama.






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ap 6. DDT application in Mexico - 1988 to 1997. The background color represents the total amount of pesticides (in tons) applied in Mexican states during the period under analysis. The southern states of Guerrero, Oaxaca, and Chiapas are the ones that received larger amounts of pesticides. The graphs represent the annual amounts of DDT used for spraying households. The gradual reduction of DDT use since 1991 becomes clear.


Map 7. DDT Use in El Salvador. The Counties are classified in standard deviations with regard to the average application of DDT (in kg) per unit of area. The average DDT use per group of Counties was 210,587 kg. Chalatenango shows an annual application of DDT three times above the average value.

M
ap 8. Total cases of malaria in Panama during the year 2000. The background color shows the total positive cases of malaria by County, grouped according to the natural break method.

The dots represent the number of positive cases and the type of parasite: Plasmodium vivax = yellow and P. falciparum = red (1 dot = 1 case)..The Counties of Blas and Bocas del Toro report the greatest number of cases with P. vivax, while the Counties of Chiriqui and Panama report the highest incidence of P. falciparum












Map 9. Population at malaria risk in Guatemala. The background in different tones of gray represents the population density of Guatemala by County (inhabitants by km2); the graphs show the positive cases of malaria with relation to the total population by County.


Map 10. Distribution of malaria cases in Guatemala . This map shows the cartographic correlation between malaria, altitude and hydrography. Each point represents 100 annual cases of malaria from 1960 to 2000. Altitudes under 1000 meters are shown in green. Greater concentrations of malaria cases are observed in Counties located in altitudes under 1000 meters above sea level.


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ap 11. Standard deviations of the annual average API in Guatemala. The average API by Counties in Guatemala is 11.11 cases per every 1000 at risk population. Petén is three standard deviations above the annual average, while Alta Verapaz follows with two standard deviations. The Counties of Quetzaltenango and Guatemala are in the opposed extreme with two deviations under the annual average API.







Map12. Annual variation of positive malaria cases in the Counties of Guatemala: 1960 to 2000. The columns represent the total of positive cases, and the changes of color and tone, the decade. The active band (hot link) is available to a videotape showing the evolution of the cases of malaria in Guatemala for the same analysis period.















Map 13. Concentration of positive cases of Malaria in the east of Petén County of Guatemala. Positive Malaria cases by Plasmodium vivax are represented by orange circles; the cases of Plasmodium falciparum are represented by red triangles; most cases concentrate in the municipalities of Sayaxche and La Libertad, to the east of the County of Petén.





















Map 14. Distance of Health Centers with relation to the municipalities of Sayaxche and La Libertad. The location of the health centers and their areas of influence are measured by polygons of Thiessen, as well as the linear distances toward the localities classified according to the local API. The lines in yellow and red represent distances greater than 5 km (equivalent to 1 hour walking). With this information it is possible to prioritize actions based on the distance of health services and the API above the average local.















Map 15. Total application of DDT by total households. The localities are represented in green circles according to the potential for total DDT application. The calculation was carried out under the assumptions that the average surface of 200 m2 had been sprayed twice a year with 2g of DDT per m2. The surface water bodies are shown, as well as the potential areas of impact within a distance of 5 km from the main streams and rivers. The red dots show places where greater amounts of DDT were applied that are within a distance of 5 km from the rivers.





Annex H: Bibliographical references of documents produced during the PDF-B phase



  1. Instituto de Salud, Ambiente y Trabajo S.C.: Diagnóstico Situacional del Uso de DDT y el Control de la Malaria – Informe Regional para México y Centroamérica. (Ing. Mario Caballero-Ramírez). Mexico, Septiembre 2001.


  1. Belize – Ministry of Health: Diagnostic Situation on the use of DDT and the Control and Prevention of Malaria in Belize., Vector Control Unity (Mario Fernandez) July 2001, 37p.


  1. Costa Rica – Ministerio de Salud: Diagnóstico Situacional de la Malaria y el uso del DDT en Costa Rica., San José, Costa Rica, 2001.


  1. El Salvador - Ministerio de Salud Publica y Asistencia Social: Diagnóstico Situacional del uso del DDT en los Programas de Control de Vectores en El Salvador.– Gerencia de Atención Integral de Salud Ambiental – Departamento de Zoonosis/Vectores. (Manuel Rodriguez Cedillos, Roberto de Jesus Cardoza, José Eduardo Romero Chévez) San Salvador, El Salvador, Agosto de 2001.


  1. Guatemala - Ministerio de Salud Publica y Asistencia Social: Diagnóstico Situacional de Uso del DDT y el Control de la Malaria. (Tamara Belzabel Obispo A.), Republica de Guatemala, Septiembre 2001.


  1. Honduras - Secretaria de Salud: Diagnostico Situacional del Uso de DDT y el Control de la Malaria., Sub-Secretaria de Riesgos Poblacionales, Dirección General de Riesgos Poblacionales, Departamento de Enfermidades Transmitidas por Vectores. Tegucigalpa, Honduras, Agosto de 2001.


  1. Mexico - Secretaria de Salud: Situación Actual de la Malaria y el Uso de DDT en México. Centro Nacional de Salud Ambiental, Centro de Vigilancia Epidemiológica (Esperanza Gallardo Díaz, Victor Borja Aburto, Jorge Mendez Galván, Gustavo Sánchez Tejeda, Hector Olguin Bernal, Jorge Ramírez Hernandez). México, Diciembre, 2000. 53p.


  1. Nicaragua: Diagnostico Situacional del Uso del DDT y el Control de la Malaria. Ministerio de Salud, Dirección de Enfermedades Transmitidas por Vectores. Nicaragua, 2001.


  1. Panama: Diagnóstico Situacional del uso del DDT y el control de la Malaria en Panamá. Ministerio de Salud de Panamá (Cecilia del Rosario Guerra, Carlos Victoria, Manuel de la Crua). Panamá, marzo, 2001.


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