Medical Entomology & Biology of Disease Vectors 2024

Head of Laboratory: Dr. Khamsing Vongphayloth, MD, PhD
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The Medical Entomology and Vector-borne Disease Laboratory at Institut Pasteur du Laos is one of the most active medical entomology laboratories in Laos as well as in Southeast Asia. In order to identify common and emerging vector-borne pathogens in Laos, the medical entomology lab has established studies to assess the distribution and potential for infection transmission of diverse arthropod vectors such as ticks, chigger mites, mosquitoes, sandflies, bat flies, etc. Our lab uses different approaches for taxonomic studies of arthropod vectors, in particular combination of traditional morphological taxonomy and modern molecular techniques. Both known and unknown pathogens related to arthropods are also investigated by molecular techniques using pan-genus PCRs and by Next Generation Sequencing in collaboration with different other laboratories.

In addition, the entomology lab is setting up a pilot program for a better understanding of climatic impacts on the tick vectors and their associated pathogens. This study could be a pilot project to support the future development of a country and/or regional health surveillance system on tick-borne diseases.

In order to build sustainable local capacity in Laos to investigate and respond to vector-borne diseases as well as other emerging zoonotic viral diseases, our laboratory has also provided on-the-job training for young Lao students.

Executive summary

Vector-borne diseases pose a significant infectious disease risk to populations. Over the last decades, emerging vector-borne diseases have become one of the most critical public health problems. These diseases are often neglected in low-income countries like Laos due to a lack of diagnostic tools and appropriate surveillance systems.

Ectoparasite and pathogen surveillance in Laos

In 2024, we pursued our collaboration with the US Navy Medical Research Unit Two (NAMRU-2) in Singapore and with the Institut Pasteur un Paris on the Ectoparasite and Pathogen Surveillance in Laos (TickMap7) project.

Ectoparasite and pathogen studies in Laos were initiated in 2014 to assess the distribution of ticks and other ectoparasites, such as chigger mites, and their associated pathogens (arboviruses and Rickettsia) using classical molecular methods, including PCR and Next-Generation Sequencing (NGS).

This year, field collections were conducted in two provinces: Luangnamtha and Phongsaly. From 2023 to 2024, we collected and identified 4,505 ticks and ectoparasites, uncovering 12 species across five genera, with Rhipicephalus microplus tick being the most abundant. Molecular analysis revealed the presence of Candidatus Rickettsia jingxinensis in Rhipicephalus ticks.

NGS analysis of tick samples from 2019 to 2023 identified at least 62 viral families, including Flaviviridae, Phenuiviridae, Nairoviridae and highlighting the diversity of the tick virome in Laos.

In the coming year, we will continue our studies of the viral families of interest through detailed NGS data analysis while improving molecular techniques for detecting Rickettsia spp.

We will also investigate the effects of climate change on tick ecology and pathogen transmission dynamics to support the development of a national or regional surveillance system, with a focus on protecting vulnerable rural populations.

Mosquitoes and sandflies with their related pathogens in Laos

In 2024, we continued studying the diversity and abundance of mosquito and sandfly populations in Laos, based on collections conducted across six provinces from 2021 to 2024. Morphological identification of mosquitoes revealed the presence of 69 mosquito species across 11 genera, showcasing the rich biodiversity of mosquito species in the region. Laboratory screening by RT-PCR detected flaviviruses in mosquito pools and phleboviruses in sandfly pools, indicating the active circulation of these arboviruses among mosquitoes and sandflies in Laos.

The public health significance of these viruses is not yet fully understood. Future research will focus on analyzing NGS data to molecularly characterize flaviviruses and phleboviruses, aiming to better understand their evolutionary relationships and transmission dynamics. Additionally, further collections and molecular screenings will be conducted to expand knowledge of vectors and virus distribution.

Plain language summary

Diseases spread by insects and ticks represent a big health problem. In Laos, these diseases are often ignored because there aren’t enough tools to detect them.

Tick and Ectoparasite Research.

In 2024, we worked with international partners to study ticks and other ectoparasites in Laos. Since 2014, we’ve been checking their diversity and trying to identify diseases they could carry, like Rickettsia bacteria and some particular viruses.

This year, we collected over 4,500 ticks and other ectoparasites from two provinces. We found 12 types of ticks. Some of these ticks carried Rickettsia bacteria. We also found at least 62 different families of viruses. Next, we’ll improve our methods to detect and study these bacteria and viruses. We’ll also look at how climate change could affect ticks and the pathogens they harbor.

Mosquito and Sandfly Research.

In 2024, we studied mosquitoes and sandflies in six provinces. We identified at least 69 types of mosquitoes and detected viruses in both mosquitoes and sandflies. These viruses, known as flaviviruses and phleboviruses, include some types that are known to cause illnesses in other regions. However, their full impact in Laos remains unclear.

The next steps include studying these viruses in more detail and collecting more mosquitoes and sandflies to see how they spread diseases. This work will help us prevent disease outbreaks in Laos in the future.

Team:

Head of Laboratory
Dr. Khamsing Vongphayloth, MD, PhD

Research Engineer
Mrs. Somsanith Chonephetsarath

Research Engineer (Master student, year 1)
Dr. Tiger Soulaphy, MD

Laboratory technicians
Ms. Phonesavanh Luangamath
Mr. Khaithong Lakeomany
Mrs. Vaekey Vungkyly
Mrs. Somphat Nilaxay
Mr. Beexiong Nilaphonexay

Trainees
Mr. Tavun Pongsanarm
Ms. Calista Chanthavady

Project carried on in the lab:

+ Ectoparasite and pathogen surveillance in Laos (TickMap 7)
+ Research on mosquitoes, sandflies and their related pathogens in Laos