Vientiane, Laos
Vientiane, Laos

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Hiscox A.,Wageningen University | Kaye A.,London School of Hygiene and Tropical Medicine | Vongphayloth K.,Institute Pasteur du Laos | Banks I.,London School of Hygiene and Tropical Medicine | And 5 more authors.
American Journal of Tropical Medicine and Hygiene | Year: 2013

We assessed risk factors for vectors of dengue and chikungunya viruses near a new hydroelectric project, Nam Theun 2, in Laos. Immature stages of Aedes aegypti were found only in sites within 40 km of the urban provincial capital, but Aedes albopictus was found throughout. Aedes aegypti pupae were most common in water storage jars (odds ratio [OR] = 4.72) and tires (OR = 2.99), and Ae. albopictus pupae were associated with tires in 2009 (OR = 10.87) and drums, tires, and jars in 2010 (drums OR = 3.05; tires OR = 3.45, jars OR = 6.59). Compared with water storage vessels, containers used for hygiene, cooking, and drinking were 80%less likely to harbor Ae. albopictus pupae in 2010 (OR = 0.20), and discarded waste was associated with a 3.64 increased odds of infestation. Vector control efforts should focus on source reduction of water storage containers, particularly concrete jars and tires. Copyright © 2013 by The American Society of Tropical Medicine and Hygiene.


Borthwick N.,University of Oxford | Borthwick N.,Weatherall Institute of Molecular Medicine | Ahmed T.,University of Oxford | Ahmed T.,Weatherall Institute of Molecular Medicine | And 24 more authors.
Molecular Therapy | Year: 2014

Virus diversity and escape from immune responses are the biggest challenges to the development of an effective vaccine against HIV-1. We hypothesized that T-cell vaccines targeting the most conserved regions of the HIV-1 proteome, which are common to most variants and bear fitness costs when mutated, will generate effectors that efficiently recognize and kill virus-infected cells early enough after transmission to potentially impact on HIV-1 replication and will do so more efficiently than whole protein-based T-cell vaccines. Here, we describe the first-ever administration of conserved immunogen vaccines vectored using prime-boost regimens of DNA, simian adenovirus and modified vaccinia virus Ankara to uninfected UK volunteers. The vaccine induced high levels of effector T cells that recognized virus-infected autologous CD4 + cells and inhibited HIV-1 replication by up to 5.79 log 10. The virus inhibition was mediated by both Gag- and Pol- specific effector CD8 + T cells targeting epitopes that are typically subdominant in natural infection. These results provide proof of concept for using a vaccine to target T cells at conserved epitopes, showing that these T cells can control HIV-1 replication in vitro. © The American Society of Gene & Cell Therapy.


Hiscox A.,Institute Pasteur du Laos | Hiscox A.,London School of Hygiene and Tropical Medicine | Khammanithong P.,Khammouane Provincial Health Office | Kaul S.,Nam Theun 2 Power Company | And 5 more authors.
PLoS ONE | Year: 2013

Background:Construction of the Nam Theun 2 hydroelectric project and flooding of a 450 km2 area of mountain plateau in south-central Lao PDR resulted in the resettlement of 6,300 people to newly built homes. We examined whether new houses would have altered risk of house entry by mosquitoes compared with traditional homes built from poorer construction materials.Methodology/Principal Findings:Surveys were carried out in the Nam Theun 2 resettlement area and a nearby traditional rice farming area in 2010. Mosquitoes were sampled in bedrooms using CDC light traps in 96 resettlement houses and 96 traditional houses and potential risk factors for mosquito house entry were recorded. Risk of mosquito house entry was more than twice as high in traditional bamboo houses compared with those newly constructed from wood (Putative Japanese Encephalitis (JE) vector incidence rate ratio (IRR) = 2.26, 95% CI 1.38-3.70, P = 0.001; Anopheline IRR = 2.35, 95% CI: 1.30-4.23, P = 0.005). Anophelines were more common in homes with cattle compared against those without (IRR = 2.32, 95% CI: 1.29-4.17, P = 0.005).Wood smoke from cooking fires located under the house or indoors was found to be protective against house entry by both groups of mosquito, compared with cooking in a separate room beside the house (Putative JE vector IRR = 0.43, 95% CI: 0.26-0.73, P = 0.002; Anopheline IRR = 0.22, 95% CI: 0.10-0.51, P<0.001).Conclusions/Significance:Construction of modern wooden homes should help reduce human-mosquito contact in the Lao PDR. Reduced mosquito contact rates could lead to reduced transmission of diseases such as JE and malaria. Cattle ownership was associated with increased anopheline house entry, so zooprophylaxis for malaria control is not recommended in this area. Whilst wood smoke was protective against putative JE vector and anopheline house entry we do not recommend indoor cooking since smoke inhalation can enhance respiratory disease. © 2013 Hiscox et al.


Tangena J.-A.A.,Institute Pasteur du Laos | Tangena J.-A.A.,Durham University | Thammavong P.,Institute Pasteur du Laos | Wilson A.L.,Durham University | And 2 more authors.
Trends in Parasitology | Year: 2016

Unprecedented economic growth in Southeast Asia (SEA) has encouraged the expansion of rubber plantations. This land-use transformation is changing the risk of mosquito-borne diseases. Mature plantations provide ideal habitats for the mosquito vectors of malaria, dengue, and chikungunya. Migrant workers may introduce pathogens into plantation areas, most worryingly artemisinin-resistant malaria parasites. The close proximity of rubber plantations to natural forest also increases the threat from zoonoses, where new vector-borne pathogens spill over from wild animals into humans. There is therefore an urgent need to scale up vector control and access to health care for rubber workers. This requires an intersectoral approach with strong collaboration between the health sector, rubber industry, and local communities. © 2016 Elsevier Ltd.


PubMed | Institute Pasteur du Laos, Durham University and London School of Hygiene and Tropical Medicine
Type: Journal Article | Journal: Medical and veterinary entomology | Year: 2016

During the resettlement of 6500 persons living around the Nam Theun 2 hydroelectric project in Laos, more than 1200 pour-flush latrines were constructed. To assess the role of these latrines as productive larval habitats for mosquitoes, entomological investigations using Centers for Disease Control (CDC) light traps, visual inspection and emergence trapping were carried out in over 300 latrines during the rainy seasons of 2008-2010. Armigeres subalbatus (Diptera: Culicidae) were nine times more likely to be found in latrines (mean catch: 3.09) than in adjacent bedrooms (mean catch: 0.37) [odds ratio (OR) 9.08, 95% confidence interval (CI) 6.74-15.11] and mosquitoes were active in and around 59% of latrines at dusk. Armigeres subalbatus was strongly associated with latrines with damaged or improperly sealed septic tank covers (OR 5.44, 95% CI 2.02-14.67; P < 0.001). Armigeres subalbatus is a nuisance biter and a putative vector of Japanese encephalitis and dengue viruses. Dengue virus serotype 3 was identified from a single pool of non-blood-fed female A. subalbatus using reverse transcription polymerase chain reaction. Maintaining a good seal around septic tanks by covering them with a layer of soil is a simple intervention to block mosquito exit/entry and contribute to vector control in resettlement villages. The scale-up of this simple, cheap intervention would have global impact in preventing the colonization of septic tanks by nuisance biting and disease-transmitting mosquitoes.


PubMed | Institute Pasteur du Laos and Durham University
Type: Journal Article | Journal: Trends in parasitology | Year: 2016

Unprecedented economic growth in Southeast Asia (SEA) has encouraged the expansion of rubber plantations. This land-use transformation is changing the risk of mosquito-borne diseases. Mature plantations provide ideal habitats for the mosquito vectors of malaria, dengue, and chikungunya. Migrant workers may introduce pathogens into plantation areas, most worryingly artemisinin-resistant malaria parasites. The close proximity of rubber plantations to natural forest also increases the threat from zoonoses, where new vector-borne pathogens spill over from wild animals into humans. There is therefore an urgent need to scale up vector control and access to health care for rubber workers. This requires an intersectoral approach with strong collaboration between the health sector, rubber industry, and local communities.


Grandadam M.,Institute Pasteur du Laos | Kamgang B.,Institute Pasteur Of Bangui | Herve J.P.,IRD Montpellier | Rogier C.,Institute Pasteur Of Madagascar | And 3 more authors.
PLoS Neglected Tropical Diseases | Year: 2014

Background:Dengue is not well documented in Africa. In Cameroon, data are scarce, but dengue infection has been confirmed in humans. We conducted a study to document risk factors associated with anti-dengue virus Immunoglobulin G seropositivity in humans in three major towns in Cameroon.Methodology/Principal Findings:A cross sectional survey was conducted in Douala, Garoua and Yaounde, using a random cluster sampling design. Participants underwent a standardized interview and were blood sampled. Environmental and housing characteristics were recorded. Randomized houses were prospected to record all water containers, and immature stages of Aedes mosquitoes were collected. Sera were screened for anti-dengue virus IgG and IgM antibodies. Risk factors of seropositivity were tested using logistic regression methods with random effects.Anti-dengue IgG were found from 61.4% of sera in Douala (n = 699), 24.2% in Garoua (n = 728) and 9.8% in Yaounde (n = 603). IgM were found from 0.3% of Douala samples, 0.1% of Garoua samples and 0.0% of Yaounde samples. Seroneutralization on randomly selected IgG positive sera showed that 72% (n = 100) in Douala, 80% (n = 94) in Garoua and 77% (n = 66) in Yaounde had antibodies specific for dengue virus serotype 2 (DENV-2).Age, temporary house walls materials, having water-storage containers, old tires or toilets in the yard, having no TV, having no air conditioning and having travelled at least once outside the city were independently associated with anti-dengue IgG positivity in Douala. Age, having uncovered water containers, having no TV, not being born in Garoua and not breeding pigs were significant risk factors in Garoua. Recent history of malaria, having banana trees and stagnant water in the yard were independent risk factors in Yaounde.Conclusion/Significance:In this survey, most identified risk factors of dengue were related to housing conditions. Poverty and underdevelopment are central to the dengue epidemiology in Cameroon. © 2014 Demanou et al.


Choumet V.,Institute Pasteur Paris | Attout T.,CNRS Systematics, Biodiversity and Evolution Institute | Chartier L.,Institute Pasteur Paris | Khun H.,Institute Pasteur Paris | And 6 more authors.
PLoS ONE | Year: 2012

Background: Anopheles gambiae is a major vector of malaria and lymphatic filariasis. The arthropod-host interactions occurring at the skin interface are complex and dynamic. We used a global approach to describe the interaction between the mosquito (infected or uninfected) and the skin of mammals during blood feeding. Methods: Intravital video microscopy was used to characterize several features during blood feeding. The deposition and movement of Plasmodium berghei sporozoites in the dermis were also observed. We also used histological techniques to analyze the impact of infected and uninfected feedings on the skin cell response in naive mice. Results: The mouthparts were highly mobile within the skin during the probing phase. Probing time increased with mosquito age, with possible effects on pathogen transmission. Repletion was achieved by capillary feeding. The presence of sporozoites in the salivary glands modified the behavior of the mosquitoes, with infected females tending to probe more than uninfected females (86% versus 44%). A white area around the tip of the proboscis was observed when the mosquitoes fed on blood from the vessels of mice immunized with saliva. Mosquito feedings elicited an acute inflammatory response in naive mice that peaked three hours after the bite. Polynuclear and mast cells were associated with saliva deposits. We describe the first visualization of saliva in the skin by immunohistochemistry (IHC) with antibodies directed against saliva. Both saliva deposits and sporozoites were detected in the skin for up to 18 h after the bite. Conclusion: This study, in which we visualized the probing and engorgement phases of Anopheles gambiae blood meals, provides precise information about the behavior of the insect as a function of its infection status and the presence or absence of anti-saliva antibodies. It also provides insight into the possible consequences of the inflammatory reaction for blood feeding and pathogen transmission. © 2012 Choumet et al.


Jutavijittum P.,Chiang Mai University | Andernach I.E.,Institute of Immunology | Yousukh A.,Chiang Mai University | Samountry B.,Health Science University | And 6 more authors.
Vox Sanguinis | Year: 2014

Background and Objectives: In Lao People's Democratic Republic, hepatitis B virus is highly endemic. However, blood donations are only screened for HBsAg, leaving a risk of transmission by HBsAg-negative occult infected donors. Here, we characterized first-time blood donors to assess prevalence of hepatitis B virus infections and occult infected donors. Materials and Methods: Sera were screened for HBsAg, HBeAg and anti-HBs, anti-HBc and anti-HBe antibodies. Occult HBV infections (OBIs) were assessed in HBsAg-negative sera by PCR, and sera of HBsAg positive and occult infected donors were phylogenetically characterized. Results: 9·6% of the donors were HBsAg positive, and 45.5% were positive for at least one of the hepatitis B virus serum markers. More than 40% HBsAg carriers were HBeAg positive, with HBeAg seroconversion occurring around 30 years of age. Furthermore, 10·9% of HBsAg-negative, anti-HBc and/or anti-HBs-positive donors were occult infected with hepatitis B virus. Thus, at least 3·9% of blood donations would potentially be unsafe, but hepatitis B virus DNA copy numbers greatly varied between donors. Conclusion: In Lao People's Democratic Republic, a sizable proportion of HBsAg-negative and anti-HBc antibody-positive blood donations are potentially DNA positive and infective for hepatitis B. © 2013 International Society of Blood Transfusion.


Lee W.-J.,Seoul National University | Brey P.T.,Institute Pasteur du Laos
Annual Review of Cell and Developmental Biology | Year: 2013

Since Metchnikoff developed his views on the intestinal microflora, much effort has been devoted to understanding the role of gut microbiomes in metazoan physiology. Despite impressive data sets that have been generated by associating a phenotype-causing commensal community with its corresponding host phenotype, the field continues to suffer from descriptive and often contradictory reports. Hence, we cannot yet draw clear conclusions as to how the modifications of microbiomes cause physiological changes in metazoans. Unbiased, large-scale genetic screens to identify key genes, on both microbial and host sides, will be essential to gain mechanistic insights into gut-microbe interactions. The Drosophila genome-commensal microbiome genetic model has proven to be well suited to dissect the complex reciprocal cross talk between the host and its microbiota. In this review, we present a historical account, current views, and novel perspectives for future research directions based on the insights gleaned from the Drosophila gut-microbe interaction model. © 2013 by Annual Reviews. All rights reserved.

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