In Southeast Asia (SEA), a range of tick-borne pathogens (TBPs) circulate, including Anaplasma, Borrelia, Babesia, Coxiella, Ehrlichia, Rickettsia, and Theilaria. The detection of these pathogens typically employs various methodologies, ranging from basic methods such as blood smear examination, rapid diagnostic kits, and PCR to more sophisticated methods such as sequencing analysis. However, the availability of more advanced diagnostic tools may be limited to renowned universities or research institutes.

To address the growing threat posed by ticks and tick-borne diseases (TBDs) and the disparity in diagnostic capabilities between SEA countries, the establishment of a sustainable network of experts is necessary, facilitating collaborations among multidisciplinary researchers not only from the region but also from the world. The main focus of this network will be to improve the sharing of resources and knowledge to enhance the surveillance, diagnosis, and management of ticks and TBDs. The initial step in accomplishing this goal involves gathering experts from various regions to engage in comprehensive discussions and exchange scientific perspectives through an international symposium, with a particular focus on the Southeast Asian context.

On June 22 and 23, 2023, the first international symposium on ticks and TBDs in SEA was held in Phnom Penh, Cambodia. The symposium was organized by the Institut Pasteur du Cambodge (IPC) in collaboration with the Royal University of Agriculture and the Ministry of Agriculture, Forestry and Fisheries.

The main objective of the symposium was to create a network of experts on ticks and associated pathogens in SEA and promote knowledge transfer and emulation around this emerging topic within the region. Featuring participants from over 10 nationalities, this symposium served as an extensive platform to engage discussion about the current knowledge on ticks and TBDs. It offers optimism in the collective effort to fight against these diseases in the context of climate change and the “One Health” initiative.

This paper provides a summary of the symposium’s presentations and discussion, organized into 3 main parts. The first section addresses the current state of knowledge on ticks and TBDs in SEA countries that were present at this symposium. The contributions made by participants from Cambodia, Indonesia, Laos, Malaysia, Thailand, and Vietnam in their respective presentations collectively enhance the comprehension of a part of the regional knowledge landscape. The second part focuses on the development of new research approaches related to TBPs and TBDs that were presented during the symposium. The last part synthetizes insights from the round table discussion held on the final day, with the aim of identifying the most important challenges and offering recommendations for future research on TBPs and TBDs in the SEA region. The following text synthetized the presentations and the discussions occurring during the symposium.

Southeast Asia nations are known for their diverse ecosystems, tropical rainforests, and abundant wildlife. They also host a variety of tick species that play an important role in the transmission of TBDs, highlighting the importance of performing studies on ticks in this region. Scientists from 6 SEA countries summarized and presented their work on ticks covering the taxonomical studies and TBPs detection from both tick vectors and animals. Although representatives from other SEA countries attended the symposium, they did not present their work in this session. Therefore, the data from their countries are not included in this current article.

In the farm setting, a total of 3,534 ticks were collected from 79 cattle across 8 farms. These belong to 2 species: Rhipicephalus australis and Rh. microplus. Notably, no ticks were found on either chickens or pigs. In the other 3 habitats, we found 3,139 ticks belonging to 13 species. These include 6 new record species for the country: 1 soft tick species (Carios batuensis, formerly Ornithodoros batuensis) and 5 hard tick species (Dermacentor filippovea, Dermacentor steini, Haemaphysalis canestrinii, Haemaphysalis hystricis, and Haemaphysalis wellingtoni).

These newly recorded species were found in different locations. While O. batuensis was collected in bat caves in Stung Treng province, De. filippovea was sampled on wild pigs in Koh Kong province and Ha. canestrinii on a dog in Kratie province. The 3 other species were found on the vegetation at the forest fringes in Kampong Chhnang, Kampong Thom, and Stung Treng provinces.

No integrated tick control method has been implemented nationwide and the research into integrated tick management strategies remains a challenge in Cambodia. Indeed, tick control measures rely on traditional techniques carried out by individual owners, including manual hand picking, applying salts or tobacco to cattle, and burning grass near cattle shelters, even if some owners opt for commercial insect spray and antiparasitic medicine such as Ivermectin.

All things considered, the circulation of TBDs seems to be confirmed at a larger scale in Cambodia. Significant strengthening of research on ticks and TBD in human and veterinary medicine is needed to better understand their biology and evaluate tick-related risk in this country.

Thailand is also home to open Zoos located within wildlife sanctuaries, such as the zoo in Chonburi province, featuring a diverse collection of over 300 animal species. And certain wild species are able to move between these 2 zones (zoo and wild areas), and TBPs could potentially be transmitted among wild animals. Given the variety of species and transmission possibilities, the Open Zoo can be an excellent resource for studying tick diversity and their role as vectors of important pathogens.

A specific study conducted in this context identified 4 tick species: Rh. microplus, Ha. lagrangei, Ha. wellingtoni, and De. auratus. In these ticks, Anaplasma spp. exhibited the highest infection rate (247/425), followed by Babesia spp. (130/425), and Theileria spp. (71/425). Coinfections and tri-infections were found in some collected ticks.

These findings indicate that certain tick species in Thailand could potentially spread TBDs to wild animals in open zoos. This hypothesis is corroborated by the detection of related pathogens in the areas studied. The information obtained could be useful in developing plans for the treatment, prevention, and management of TBDs. However, further research is needed to determine the ability of ticks to transmit these pathogens and to better understand the relationship between pathogens, ticks, and hosts.

Recent scientific investigations conducted over the past decade reveal a pronounced abundance and extensive distribution of tick species. Reports also indicated that TBPs are frequently overlooked, despite their prevalence in both humans and animals. The occurrence of TBDs in humans and domestic animals is currently on the rise in Vietnam. Consequently, there is a pressing need to advance research efforts focused on ticks and TBDs.

The initial presentation session offered valuable insights into the current knowledge, areas of focus, and shared interests regarding tick studies in 6 SEA countries. The presentations continued on the progress made in research, with particular emphasis on advances at the proteomic and molecular levels. These include the development of new techniques for identifying tick vectors and their associated pathogens, the creation of vaccines, and the establishment of tick cell lines. It is important to note that these research advances have not been carried out exclusively by SEA countries, but rather by partners from other countries. This session holds significant importance as it provides a platform to familiarize participants with the research and facilities managed by other research groups.

In conclusion, proteomic techniques can be used differently in epidemiological studies to measure vector competence. MALDI-TOF MS has proved highly effective in accurately identifying tick species. In the vertebrate host, targeted proteomics could be used to identify markers of infection. However, pathogen detection in ticks is still better by molecular biology than by proteomics.

Despite the thriving in tick cell line research worldwide, its application in low- and middle-income countries has been limited, probably due to difficulties associated with availability, propagation, and maintenance of tick cell lines. To address these issues, the Tick Cell Biobank (TCB) was established to offer tick cell lines for research and training. The main TCB is located at the University of Liverpool, with 3 additional outposts in Asia, Africa, and South America. The TCB Asia Outpost was established in 2018 at the Tropical Infectious Diseases and Education Centre (TIDREC), Universiti Malaya, Malaysia, to provide tick cell resources and training to researchers in Asia. Currently, this outpost houses a total of 18 hard ticks’ cell lines comprising different strains of Amblyomma, Dermacentor, Hyalomma, Ixodes, and Rhipicephalus species. This outpost also aims to establish tick cell lines indigenous to SEA, as the cell lines available in the collections originated from the United States of America, Europe, the United Kingdom, and Africa, reinforcing their relevance to the study of endemic ticks and TBDs in this region.

The final session of the symposium features a roundtable discussion involving all the participants, separated into 3 groups. This session aimed to highlight the main difficulties encountered by the different laboratories and governmental entities, and to identify the major challenges and the priorities for the future researches on ticks and TBDs. The outcomes are summarized below in 2 different sections.

The 3 working groups identified the lack of talents dedicated to the subjects of ticks and TBD studies as the main problem. This can be explained by a lack of training, research projects, visibility, and awareness of TBDs. The modest perception of veterinary diseases and veterinarians in certain countries, as well as the lack of knowledge of TBDs among humans in comparison to widely known mosquito-borne diseases, could explain this lack of visibility. In addition and directly related to this first point, the lack of capacity-building at universities on these topics could also explain the difficulty of recruiting potential students and researchers. Indeed, a strong lack of interest and attractiveness is observed across multiples countries. In some countries, such as Cambodia, recognizing TBDs and their symptoms are not taught at the University of Science. Moreover, the scarcity of tick taxonomists, coupled with considerable time investment necessary for taxonomic training and the absence of universally applicable tick species determination key, pose a significant problem on developing researches on ticks and TBDs. Consequently, university programs related to vector-borne diseases, one-health and planetary health, especially in related medical-veterinary faculties, should be revised and continuously updated to reflect the current situation of ticks and TBDs in SEA.

Securing funding for tick research is consistently a common difficulty faced by SEA countries. Indeed, all 3 working groups mentioned the problem of research visibility, not only with regard to funders and donors, but also to public decision-makers and governments. Researches in veterinary entomology, particularly regarding ticks and TBDs, are not recognized as a priority in Southeast Asia, despite the significant financial impact of these diseases on livestock farming. Thus, it is important to enhance visibility and awareness of ticks and TBDs among various stakeholders in this region regarding their impacts on both animal and human health and socioeconomic aspects. To achieve this, scientists need to be able to draw on human and animal epidemiological studies, as well as to work more closely with hospitals, animal clinics, and practitioners in contact with potential patients. Forging closer links with local universities and public health authorities also regarded as promising approach.

The discussion groups highlighted that working with just human and veterinary clinical institutions would not be enough to fully understand the ecology of the tick vectors. Multidisciplinary collaborations among research institutes, clinics, conservation groups, animal researchers, and livestock associations (both private and governmental) are necessary to help understand various factors such as transmission efficacy, seasonal and environmental factors leading to the bloom of tick populations. This is especially critical for our colleagues who work heavily in wild areas such as agriculture workers, rangers, etc.

In a more technical aspect, one of the difficulties raised was the absence of an international freely accessible MALDI-TOF MS database for identifying ticks based on their protein spectra, similar to how GenBank serves for species identification through DNA sequences. Establishing such a free-access database will enable species identification at low cost, a factor considered crucial in resource-limited countries. The potential risk for a future privatization of this database poses a threat to progress made in MALDI-TOF MS research in both veterinary and medical entomology. Finally, the absence of dedicated genomic research was emphasized, particularly considering the extensive size of tick genome, thereby increasing the cost of full genome sequencing. Furthermore, the lack of tick survey and collection in SEA also contributes to the scarcity of tick specimens for genomic analyses.

The difficulty of establishing tick colonies in the laboratory has also been recognized as an obstacle in research on TBDs. This difficulty primarily arises challenges in breeding ticks due to: (i) their strict hematophagous behavior requiring prolonged and substantial blood meal; (ii) the variation in host preference among species complicating the use of a one single host for laboratory breeding; and (iii) the complexities involved in setting up an artificial feeding system. Breeding ticks in laboratory could therefore be expensive, requiring substantial quantities of blood that are logistically challenging to obtain in some developing countries.

The initiation of this symposium, the enthusiasm it has generated, and the meetings of scientists working on ticks and their associated diseases is a first step towards establishing a regional network that will have the ambition to last. One of the most difficult challenges will be to maintain this network and find common ground for research.

As mentioned above, the difficulties and challenges are numerous, and the priorities are more targeted and pragmatic, necessary in the first instance for large-scale research in subsequent years. The working groups have agreed to set a number of approaches to explore priorities in research. The development of the regional tick determination key validated by specialists from each country is considered as one of the initial milestones. In fact, this has been completed partially and a common tick determination key should be released in the years to come.

In parallel to that, the improvement in molecular tick identification has also been mentioned. This includes the advancement of MALDI-TOF MS protein spectra database for tick identification purposes, as well as the need to further develop tick DNA sequence database for gene barcoding. As MALDI-TOF MS was mentioned to be not currently available in many research centers, a completion of gene database for all the tick species in SEA could be better priority for the ticks and TBDs network. In addition, with the development of image recognition through machine learning, the groups raised the possibility of identifying tick adults and nymphs from photos, which would then be analyzed by machine/deep learning and made available through apps on mobile devices.

Once the tick species has been described, the next milestone will be investigating their vector competence. Indeed, the capacity of tick species to infest human or certain animal need to be thoroughly studied to evaluate the risk of pathogen transmission. For this, laboratory-reared tick colonies are needed, as well as access to BSL2 and BSL3 security laboratories depending on the pathogens handled. Access to these biosafety laboratories could be achieved through collaboration, pending the implementation of such laboratories in each country. However, maintaining multi species laboratory-reared tick colonies might be a more challenging task for various partners, as this is very difficult to set up.

With recent changes in land use, climate, and the environment, as well as changes in animal husbandry practices, close contact between man and animal (domestic or wild) is becoming very important. It is imperative to be able to detect the presence of pathogens at an early stage of infection. The use of next-generation sequencing (NGS) by countries in SEA is a key step towards describing the diversity and distribution of TBPs in this region.

With the availability of robust data on ticks, TBPs and TBDs, the next significant step is to develop a digital platform for sharing such data in a secure and efficient way. The tools exist, but there is the question of hosting the data for sharing, and the human resources involved and their responsibility. This platform will serve multiple purposes, from hosting MALDI TOF MS spectra database to hosting distribution map of different tick species, their host, and associated TBPs. Integration with other geospatial data such as land use and climate will allow the scientist to model and predict the risks of TBDs in this region.

Finally, in the framework of pathogen discoveries in ticks and vector competence studies, the development of tick cell lines is important to elucidate the various aspects of pathogen replication and pathogenesis in vitro and to better understand the host–pathogen interactions. It should be noted that almost all existing tick cell lines come from temperate countries, mainly Ixodes cells. It is imperative to develop new cell lines from tick species present and predominant in SEA. In addition, the development of tick cell lines offers the possibility of testing specific acaricides directly targeting these cells. For instance, emerging RNAi insecticides are currently developed and will be soon to be used against mosquitoes. These strategies could potentially be adapted and evaluated for their effectiveness against ticks.