The decline of malaria in Vietnam, 1991-2014

Abstract

Background: Despite the well-documented clinical efficacy of artemisinin-based combination therapy (ACT) against malaria, the population-level effects of ACT have not been studied thoroughly until recently. An ideal case study for these population-level effects can be found in Vietnam's gradual adoption of artemisinin in the 1990s.

Methods and results: Analysis of Vietnam's national annual malaria reports (1991-2014) revealed that a 10% increase in artemisinin procurement corresponded to a 32.8% (95% CI 27.7-37.5%) decline in estimated malaria cases. There was no consistent national or regional effect of vector control on malaria. The association between urbanization and malaria was generally negative and sometimes statistically significant.

Conclusions: The decline of malaria in Vietnam can largely be attributed to the adoption of artemisinin-based case management. Recent analyses from Africa showed that insecticide-treated nets had the greatest effect on lowering malaria prevalence, suggesting that the success of interventions is region-specific. Continuing malaria elimination efforts should focus on both vector control and increased access to ACT.

Keywords: Artemisinin; Malaria; Urbanization; Vector control; Vietnam.

Fig. 1

Incidence of suspected, confirmed, and estimated cases of malaria per 1000 person-years by region from 1991 to 2014 on a log-transformed scale where labels correspond to raw (unlogged) values. In 2014, there were 473 confirmed cases in the northern region, 12,006 confirmed cases in the central region, and 2,462 cases in the southern region

Fig. 2

Incidence of suspected, confirmed, and estimated cases of malaria, by province (1992–2014). Provinces are arranged approximately by decreasing latitude (north to south) from top to bottom, and left to right. The y-axis is log-transformed, but the labels correspond to raw (unlogged) values and the “0.0” label on the y-axis corresponds to true zero

Fig. 3

a Incidence of malaria in Vietnam, 2014. Incidence is calculated per 1000 person-years using the estimated number of cases. b Average positive predictive value, q, by province for the years 2010–2014

Fig. 4

Changes in covariates between 1991 and 2014 for northern, central, and southern provinces

Fig. 5

Percent change in malaria incidence associated with a 10% increase in the proportion of treatments for P. falciparum containing artemisinin (top row), proportion of the population living in urban areas (middle row), and proportion of the population protected by vector control measures (bottom row), by region and nationwide, as predicted by models using these three covariates only. The circle shows the mean effect size, the solid line shows the 95% confidence interval, and the dotted lines shows the 99.9% confidence interval. Outcome variable used in model is indicated by color. For clarity, the x-axis has been limited to range from – 90 to 90%

Fig. 6

As in Fig. 5, with the addition of covariates measuring health system capacity