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Chikungunya virus (CHIKV) is a mosquito-borne virus belonging to the genus Alphavirus. The virus is transmitted to humans by the bite of infected female Aedes mosquitoes, primarily Aedes aegypti. CHIKV infection is spreading worldwide, and it periodically sparks new outbreaks. There are no specific drugs or effective vaccines against CHIKV. The interruption of pathogen transmission by mosquito control provides the only effective approach to the control of CHIKV infection. Many studies have shown that CHIKV can be transmitted among the Ae. aegypti through vertical transmission. The previous chikungunya fever outbreaks in Thailand during 2008–2009 were caused by CHIKV, the East/Central/South African (ECSA) genotype. Recently, there have been 3794 chikungunya cases in 27 provinces reported by the Bureau of Epidemiology of Health Ministry, Thailand during 1 January–16 June 2019; however, the cause of the re-emergence of CHIKV outbreaks is uncertain. Therefore, the aims of this study were to detect and analyze the genetic diversity of CHIKV infection in field-caught mosquitoes. Both female and male Ae. aegypti were collected from endemic areas of Thailand, and CHIKV detection was done by using E1-nested RT-PCR and sequencing analysis. A total of 1646 Ae. aegypti samples (900 females and 746 males) were tested. CHIKV was detected in 54 (3.28%) and 14 samples (0.85%) in female and male mosquitoes, respectively. Seventeen samples of female Ae. aegypti collected from the Ubon Ratchathani, Chiang Rai, Chiang Mai, Nakhon Sawan, and Songkhla provinces found mutation at E1: A226V. Interestingly, E1: K211E mutation was observed in 50 samples collected from Nong Khai, Bangkok, Prachuap Khiri Khan, and Krabi. In addition, the phylogenetic tree indicated that CHIKV in Ae. aegypti samples were from the Indian Ocean Clade and East/South African Clade. Both clades belong to the ECSA genotype. The information obtained from this study could be used for prediction, epidemiological study, prevention, and effective vector control of CHIKV. For instance, a novel CHIKV strain found in new areas has the potential to lead to a new outbreak. Health authorities could plan and apply control strategies more effectively given the tools provided by this research. [ABSTRACT FROM AUTHOR]

Phlebotomine sand flies are tiny, hairy, blood-sucking nematoceran insects that feed on a wide range of hosts. They are known as a principal vector of parasites, responsible for human and animal leishmaniasis worldwide. In Thailand, human autochthonous leishmaniasis and trypanosomiasis have been reported. However, information on the vectors for Leishmania and Trypanosoma in the country is still limited. Therefore, this study aims to detect Leishmania and Trypanosoma DNA in field-caught sand flies from endemic areas (Songkhla and Phatthalung Provinces) and non-endemic area (Chumphon Province) of leishmaniasis. A total of 439 sand flies (220 females and 219 males) were collected. Head and genitalia dissection of female sandflies were done for morphology identification, and the remaining parts of those sand flies were then used for the detection of Leishmania and Trypanosoma parasites. The DNA was extracted from individual female sand flies. Polymerase chain reaction (PCR) anneal, specific to the ITS1 and SSU rRNA gene regions, was used to detect Leishmania and Trypanosoma DNA, respectively. The positive PCR products were cloned and sequenced. The results showed that the female sand fly species in this study consisted of Sergentomyia khawi (35.9%); Se. anodontis (23.6%); Phlebotomus betisi (18.6%); Ph. kiangsuensis (9.5%); Ph. asperulus (6.4%); Se. barraudi (2.3%); 0.9% of each Se. indica, Ph. stantoni, and Ph. major major; and 0.5% of each Se. sylvatica and Ph. mascomai. The PCR and sequence analysis were able to detect Leishmania and Trypanosoma DNA in sand fly samples, which were identified as L. martiniquensis, 1/220 (0.45%) in Se. khawi, 3/220 (1.36%) of T. noyesi in Se. anodontis, and Ph. asperulus. Fourteen (6.36%) of the unidentified trypanosome species in Se. khawi, Se. indica, Se. anodontis, Ph. asperulus, and Ph. betisi were found in all of the areas of this study. Interestingly, we found a 1/220 (0.45%) co-infection sample of L. martiniquensis and Trypanosoma in Se. khawi from Songkhla Province. These data indicate that several species of sand flies might be potential vectors of Leishmania and Trypanosoma parasites in southern Thailand. However, more extensive study for potential vectors using a larger number of sand flies should be conducted to prove whether these sand flies can be natural vectors of leishmaniasis and trypanosomiasis in both humans and animals. In addition, our study could be useful for the future study of infection prevention, including effective vector control for leishmaniasis and trypanosomiasis in Thailand. [ABSTRACT FROM AUTHOR]