First evidence of dengue infection in domestic dogs living in different ecological settings in Thailand

Abstract

BackgroundDengue is a vector-borne disease transmitted by Aedes mosquitoes. It is considered an important public health problem in many countries worldwide. However, only a few studies have been conducted on primates and domestic animals that could potentially be a reservoir of dengue viruses. Since domestic dogs share both habitats and vectors with humans, this study aimed to investigate whether domestic dogs living in different ecological settings in dengue endemic areas in Thailand could be naturally infected with dengue viruses.Methodology/Principal findingsSerum samples were collected from domestic dogs in three different ecological settings of Thailand: urban dengue endemic areas of Nakhon Sawan Province; rubber plantation areas of Rayong Province; and Koh Chang, an island tourist spot of Trat Province. These samples were screened for dengue viral genome by using semi-nested RT-PCR. Positive samples were then inoculated in mosquito and dog cell lines for virus isolation. Supernatant collected from cell culture was tested for the presence of dengue viral genome by semi-nested RT-PCR, then double-strand DNA products were double-pass custom-sequenced. Partial nucleotide sequences were aligned with the sequences already recorded in GenBank, and a phylogenetic tree was constructed. In the urban setting, 632 domestic dog serum samples were screened for dengue virus genome by RT-PCR, and six samples (0.95%) tested positive for dengue virus. Four out of six dengue viruses from positive samples were successfully isolated. Dengue virus serotype 2 and serotype 3 were found to have circulated in domestic dog populations. One of 153 samples (0.65%) collected from the rubber plantation area showed a PCR-positive result, and dengue serotype 3 was successfully isolated. Partial gene phylogeny revealed that the isolated dengue viruses were closely related to those strains circulating in human populations. None of the 71 samples collected from the island tourist spot showed a positive result.Conclusions/SignificanceWe concluded that domestic dogs can be infected with dengue virus strains circulating in dengue endemic areas. The role of domestic dogs in dengue transmission needs to be further investigated, i.e., whether they are potential reservoirs or incidental hosts of dengue viruses.

Animals as potential reservoirs for dengue transmission: A systematic review

“…Meta-analysis of all animal types displayed high heterogeneity (Supplementary Table 14). Overall, most of the dengue positive animals were reportedly from the urban and rural areas [ 35 , 36 , 44 , 48 , 56 , [62] , [63] , [64] , [65] , [66] , [67] , [68] , [69] , [70] , [71] , [72] , [73] , [74] ]. Otherwise, six studies involved the forest setting [ 30 , 36 , 37 , 44 , 59 , 75 ], one was in the coastal setting [ 60 ], one was unknown [ 76 ].…”

“…Third, many of the reports lacked evidence of live DENV, which is best confirmed by virus isolation, the gold standard in dengue diagnosis. Only two studies [ 48 , 63 ] in the available literature attempted and successfully isolated virus from its RT-PCR positive samples. While positivity by serology or RT-PCR test constitute indirect evidence of dengue presence in animals, they do not confirm an active infection and/or circulation of the virus among animal population.…”

Sero-epidemiological study on Dengue fever virus in humans and camels at Upper Egypt

“…However, little is known about the role of other animals as reservoirs for DENV. Some evidence exists for natural infection of domestic dogs with DENV [ 36 ]. That report is alarming since it confirmed the circulation of the virus among one common companion animal which lives in close proximity with humans.…”

Sylvatic dengue virus type 4 in Aedes aegypti and Aedes albopictus mosquitoes in an urban setting in Peninsular Malaysia

“…The growing population of Ae . albopictus and its opportunistic feeding behaviour would make it the most likely vector for transmission of DENV to both primate and non-primate hosts which may act as virus reservoirs in urban settings [47–49]. However, thus far there is no experimental evidence of this route.…”