Epidemiology of forest malaria in Central Vietnam: the hidden parasite reservoir

Malaria Journal

Research

Annette Erhart¹  Anna Rosanas-Urgell¹  Koen Peeters Grietens¹  Umberto D’Alessandro²  Nguyen Van Hong³  Tran Thanh Duong³  Pham Vinh Thanh³  Nguyen Xuan Xa³  Nguyen Van Van⁴  Nongnud Chowwiwat⁵  Germana Bancone⁵  Niko Speybroeck⁶  Carine Van Malderen⁶  Valérie Obsomer⁷ 

[1] Institute of Tropical Medicine Prince Leopold (ITM), Antwerp, Belgium;Institute of Tropical Medicine Prince Leopold (ITM), Antwerp, Belgium;Medical Research Council Unit (MRC Unit), Fajara, The Gambia;National Institute of Malariology, Parasitology and Entomology (NIMPE), Hanoi, Vietnam;Provincial Malaria Station, Tam Ky City, Quang Nam Province, Vietnam;Shoklo Malaria Research Unit, Mae Sot, Tak Province, Thailand;Université Catholique de Louvain (UCL), Brussels, Belgium;Université Ccatholique de Louvain (UCL), Louvain-la-Neuve, Belgium;

关键词: Malaria;    Sub-patent infections;    Elimination;    Central Vietnam;   

DOI  :  10.1186/s12936-015-0601-y

 received in 2014-08-04, accepted in 2015-02-01,  发布年份 2015

来源: Springer

【 摘 要 】

BackgroundAfter successfully reducing the malaria burden to pre-elimination levels over the past two decades, the national malaria programme in Vietnam has recently switched from control to elimination. However, in forested areas of Central Vietnam malaria elimination is likely to be jeopardized by the high occurrence of asymptomatic and submicroscopic infections as shown by previous reports. This paper presents the results of a malaria survey carried out in a remote forested area of Central Vietnam where we evaluated malaria prevalence and risk factors for infection.MethodsAfter a full census (four study villages = 1,810 inhabitants), the study population was screened for malaria infections by standard microscopy and, if needed, treated according to national guidelines. An additional blood sample on filter paper was also taken in a random sample of the population for later polymerase chain reaction (PCR) and more accurate estimation of the actual burden of malaria infections. The risk factor analysis for malaria infections was done using survey multivariate logistic regression as well as the classification and regression tree method (CART).ResultsA total of 1,450 individuals were screened. Malaria prevalence by microscopy was 7.8% (ranging from 3.9 to 10.9% across villages) mostly Plasmodium falciparum (81.4%) or Plasmodium vivax (17.7%) mono-infections; a large majority (69.9%) was asymptomatic. By PCR, the prevalence was estimated at 22.6% (ranging from 16.4 to 42.5%) with a higher proportion of P. vivax mono-infections (43.2%). The proportion of sub-patent infections increased with increasing age and with decreasing prevalence across villages. The main risk factors were young age, village, house structure, and absence of bed net.ConclusionThis study confirmed that in Central Vietnam a substantial part of the human malaria reservoir is hidden. Additional studies are urgently needed to assess the contribution of this hidden reservoir to the maintenance of malaria transmission. Such evidence will be crucial for guiding elimination strategies.

【 授权许可】

CC BY   
© Thanh et al.; licensee BioMed Central. 2015