Abstract | BACKGROUND: Lao People Democratic Republic (PDR; Laos), a landlocked country in Southeast Asia, has made important progress in reducing malaria morbidity and mortality in the past 5-6 years, and the northern provinces have very low reported incidence. To support national progress towards elimination, it is critical to verify and understand these changes in disease burden. METHODS: A two-stage cluster cross-sectional survey was conducted in four districts within four northern provinces (Khua, Phongsaly Province; Paktha, Bokeo Province; Nambak, Luang Prabang, and Muang Et, Huaphanh Province). During September and October 2016, demographics and malaria risk factors were collected from a total of 1492 households. A total of 5085 persons consented to collection of blood samples for testing, by rapid diagnostic test (RDT) and polymerase chain reaction (PCR)-based testing. Risk factors for infection were examined using logistic regression; and a randomized subset of males was tested for glucose-6-phosphate dehydrogenase ( G6PD) deficiencies using a combined PCR and sequencing approach. RESULTS: There were zero positives by RDT, and PCR detected Plasmodium infections in 39 (0.77%; 95% CI 0.40-1.47%) of 5082 analysable samples. The species distribution was Plasmodium vivax (28 total); Plasmodium falciparum/P. vivax (5); P. falciparum (3), Plasmodium malariae (2), and P. vivax/P. malariae (1). In multivariable analysis, the main risk factors included having any other cases within the household [aOR 12.83 (95% CI 4.40 to 37.38), p < 0.001]; and lack of bed net ownership within the household [aOR 10.91 (95% 5.42-21.94), p < 0.001]; age, sex and forest-travel were not associated with parasitaemia. A total of 910 males were tested for the six most common G6PDd in SE Asia; and 30 (3.3%; 95% CI 2.1-5.1%) had a G6PD variant allele associated with G6PD deficiency, with the majority being the Union (14) and Viangchan (11) polymorphisms, with smaller numbers of Canton and Mahidol. CONCLUSION: This is the first rigorous PCR-based population survey for malaria infection in Northern Lao PDR, and found a very low prevalence of asymptomatic Plasmodium infections by standard PCR methods, with P. vivax predominating in the surveyed districts. Clustering of cases within households, and lack of a bed nets suggest reactive case detection, and scale-up of coverage should be prioritized. The predominance of infections with P. vivax, combined with moderate levels of serious G6PD deficiencies highlight the need for careful rollout of primaquine towards elimination goals.
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Authors | Andrew A Lover, Emily Dantzer, Bouasy Hongvanthong, Keobouphaphone Chindavongsa, Susie Welty, Tania Reza, Nimol Khim, Didier Menard, Adam Bennett |
Journal | Malaria journal
(Malar J)
Vol. 17
Issue 1
Pg. 218
(Jun 01 2018)
ISSN: 1475-2875 [Electronic] England |
PMID | 29859089
(Publication Type: Journal Article)
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Topics |
- Adolescent
- Adult
- Aged
- Asymptomatic Infections
(epidemiology)
- Child
- Cluster Analysis
- Communicable Disease Control
- Cross-Sectional Studies
- Female
- Genotype
- Glucosephosphate Dehydrogenase Deficiency
(epidemiology, genetics)
- Humans
- Laos
(epidemiology)
- Malaria
(epidemiology, parasitology)
- Male
- Middle Aged
- Prevalence
- Risk Factors
- Young Adult
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