Spatio-Temporal Distribution of Plasmodium Falciparum and P. Vivax Malaria in Thailand

Abstract

Malaria incidence data at the district level from 1997 to 2002 and total malaria case data from 1965 to 2002 in Thailand were analyzed to determine the spatial and temporal dynamics of Plasmodium falciparum and P. vivax malaria incidence. Over the 37-year period, there was a 35-fold reduction in the incidence rates of P. falciparum malaria (11.86% in 1965 versus 0.34% in 2002) and a 7-fold reduction in P. vivax malaria (2.89% in 1965 versus 0.40% in 2002). The incidence ratio of P. falciparum to P. vivax malaria was reduced from 4.1 to 0.8 during this period. Malaria incidence rate exhibited the most rapid reduction between 1975 and 1985, coinciding with the introduction of a combination of antifolate drugs (sulfadoxine-pyrimethamine). The distribution maps of P. falciparum and P. vivax malaria incidence rates indicated a high spatial heterogeneity. The Thailand-Myanmar and Thailand-Cambodia border areas, where migration of foreign workers was pronounced, had the highest incidence rates for P. falciparum, P. vivax, and mixed-species infections. Transition probability analysis based on the malaria incidence rate among Thai residents indicated that there was an overall trend of decrease in the number of malaria cases and the number of high incidence districts between 1997 and 2002. High spatial variation in malaria incidence and local human migration patterns suggest that malaria control measures need to be adjusted according to local environmental and demographic settings.

Clinical and laboratory profile of Plasmodium vivax malaria patients hospitalized in Apartadó,

“…La malaria por P. vivax está ampliamente distribuida alrededor del mundo; en las regiones del sur y sureste de Asia, representa 50 % de los casos de paludismo que se presentan (2,3, Tjitra E, Warikar N, Ebsworth EP, Kenangalem E, Sugiarto P, Okoseray MJ, et al Major burden of P.vivax infection in Papua, Indonesia; A region with high levels of chloroquine resistance; 16th IFTM Medicine in the Tropics; Marseille, France. 2005).…”

Genetic structures of geographically distinct Plasmodium vivax populations assessed by PCR/RFLP analysis of the merozoite surface protein 3β gene

“…Recently, vivax malaria has re-emerged in many regions such as Korea, certain temperate provinces of China, and some former Soviet republics, where it had been largely eradicated during the global malaria control campaigns (Sleigh et al 1998;Chai et al, 1999;Sabatinelli et al, 2000;Leclerc et al, 2004). In many regions of P. vivax and P. falciparum coexistence, P. vivax has become more prevalent (Sattabongkot et al, 2004;Zhou et al, 2005). As another serious concern, P. vivax has evolved resistance to antimalarial drugs.…”

Plasmodium vivax Isolates from Cambodia and Thailand Show High Genetic Complexity and Distinct Patterns of P. vivax Multidrug Resistance Gene 1 (pvmdr1) Polymorphisms

“…[1][2][3] It is now recognized that P. vivax poses a greater challenge to malaria elimination in the region, largely caused by its propensity for relapse. 4,5 Little is known about the transmission dynamics of vivax parasites in Southeast Asia and their evolving drug resistance patterns.…”