Vector Borne Disease Section

Chiang Mai, Thailand

Vector Borne Disease Section

Chiang Mai, Thailand
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Suwonkerd W.,Vector Borne Disease Section | Vryheid R.,San Diego State University | Suwannachote N.,Vector Borne Disease Section
Southeast Asian Journal of Tropical Medicine and Public Health | Year: 2010

Thailand partially integrated the malaria program into the provincial and local Public Health system starting in 2003 by adding it to the control of other vector borne diseases and by transferring some activities to the Public Health Department. This study evaluates the results of this transfer on 8 high malaria incidence districts of Mae Hong Son and Chiang Mai Provinces. Indicators were measured for all community hospitals, Vector Borne Disease Control Units, (VBDU), health centers (HC), malaria clinics, and malaria posts in 2003 and 2004 during the first two years of partial integration. The number of Vector Borne Disease Control staff decreased 1.8 - 3%, and their operational budgets decreased 25%. The VBDU staff did all the indoor residual spraying (IRS), insecticide treated net (ITN) work and entomology surveys, they took 80.6% of the blood films, and treated 72% of the patients, while Public Health system did the remainder. The Annual Parasite Incidence (API) (1 - 10/1,000) and IRS coverage (88 - 100%) remained adequate in most areas during the first years after partial integration, but the API increased (to 31.6 - 57.6/1,000) in some populations. The percentage of insecticide treated bed net coverage was adequate in Mae Hong Son (95.4%), but inadequate in Chiang Mai (52.2%). Early diagnosis and prompt treatment (4 - 23 days), hospitals reporting disruption of anti-malarial drugs (3 of 7), and health centers having all needed equipment, training, and drugs for malaria diagnosis (9%) remain inadequate. If the program is allowed to diminish, malaria could spread again among the population. Integration of antimalarial activities into the general Public Health system has only been partially successful. We recommend the integration process and results should be monitored and evaluated to find and mitigate problems as they occur, and modify the integration process if needed.


Wipasa J.,Chiang Mai University | Suphavilai C.,Chiang Mai University | Okell L.C.,London School of Hygiene and Tropical Medicine | Cook J.,London School of Hygiene and Tropical Medicine | And 5 more authors.
PLoS Pathogens | Year: 2010

Antibodies constitute a critical component of the naturally acquired immunity that develops following frequent exposure to malaria. However, specific antibody titres have been reported to decline rapidly in the absence of reinfection, supporting the widely perceived notion that malaria infections fail to induce durable immunological memory responses. Currently, direct evidence for the presence or absence of immune memory to malaria is limited. In this study, we analysed the longevity of both antibody and B cell memory responses to malaria antigens among individuals who were living in an area of extremely low malaria transmission in northern Thailand, and who were known either to be malaria naïve or to have had a documented clinical attack of P. falciparum and/or P. vivax in the past 6 years. We found that exposure to malaria results in the generation of relatively avid antigen-specific antibodies and the establishment of populations of antigen-specific memory B cells in a significant proportion of malaria-exposed individuals. Both antibody and memory B cell responses to malaria antigens were stably maintained over time in the absence of reinfection. In a number of cases where antigenspecific antibodies were not detected in plasma, stable frequencies of antigen-specific memory B cells were nonetheless observed, suggesting that circulating memory B cells may be maintained independently of long-lived plasma cells. We conclude that infrequent malaria infections are capable of inducing long-lived antibody and memory B cell responses. © 2010 Wipasa et al.


Wipasa J.,Chiang Mai University | Okell L.,London School of Hygiene and Tropical Medicine | Okell L.,Imperial College London | Sakkhachornphop S.,Chiang Mai University | And 5 more authors.
PLoS Pathogens | Year: 2011

Immunity to malaria is widely believed to wane in the absence of reinfection, but direct evidence for the presence or absence of durable immunological memory to malaria is limited. Here, we analysed malaria-specific CD4+ T cell responses of individuals living in an area of low malaria transmission in northern Thailand, who had had a documented clinical attack of P. falciparum and/or P. vivax in the past 6 years. CD4+ T cell effector memory (CD45RO+) IFN-γ (24 hours ex vivo restimulation) and cultured IL-10 (6 day secretion into culture supernatant) responses to malaria schizont antigens were detected only in malaria-exposed subjects and were more prominent in subjects with long-lived antibodies or memory B cells specific to malaria antigens. The number of IFN-γ-producing effector memory T cells declined significantly over the 12 months of the study, and with time since last documented malaria infection, with an estimated half life of the response of 3.3 (95% CI 1.9-10.3) years. In sharp contrast, IL-10 responses were sustained for many years after last known malaria infection with no significant decline over at least 6 years. The observations have clear implications for understanding the immunoepidemiology of naturally acquired malaria infections and for malaria vaccine development. © 2011 Wipasa et al.


PubMed | Vector Borne Disease Section
Type: Journal Article | Journal: The Southeast Asian journal of tropical medicine and public health | Year: 2011

Thailand partially integrated the malaria program into the provincial and local Public Health system starting in 2003 by adding it to the control of other vector borne diseases and by transferring some activities to the Public Health Department. This study evaluates the results of this transfer on 8 high malaria incidence districts of Mae Hong Son and Chiang Mai Provinces. Indicators were measured for all community hospitals, Vector Borne Disease Control Units, (VBDU), health centers (HC), malaria clinics, and malaria posts in 2003 and 2004 during the first two years of partial integration. The number of Vector Borne Disease Control staff decreased 1.8 - 3%, and their operational budgets decreased 25%. The VBDU staff did all the indoor residual spraying (IRS), insecticide treated net (ITN) work and entomology surveys, they took 80.6% of the blood films, and treated 72% of the patients, while Public Health system did the remainder. The Annual Parasite Incidence (API) (1 - 10/1,000) and IRS coverage (88 - 100%) remained adequate in most areas during the first years after partial integration, but the API increased (to 31.6 - 57.6/1,000) in some populations. The percentage of insecticide treated bed net coverage was adequate in Mae Hong Son (95.4%), but inadequate in Chiang Mai (52.2%). Early diagnosis and prompt treatment (4 - 23 days), hospitals reporting disruption of anti-malarial drugs (3 of 7), and health centers having all needed equipment, training, and drugs for malaria diagnosis (9%) remain inadequate. If the program is allowed to diminish, malaria could spread again among the population. Integration of antimalarial activities into the general Public Health system has only been partially successful. We recommend the integration process and results should be monitored and evaluated to find and mitigate problems as they occur, and modify the integration process if needed.

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