Molecular Detection of Rickettsia felis and Rickettsia bellii in Mosquitoes

Abstract

To add to the limited information on Rickettsia in mosquitoes in China, we carried out a PCR survey on convenience samples of 3051 mosquitoes collected with hand nets in and around domestic dwellings in 25 provinces. Five species of mosquitoes were identified: Culex pipiens pallens (n = 1620), Aedes albopictus (806), Armigeres subalbatus (377), Anopheles sinensis (168), and Culex tritaeniorhynchus (80). A Rickettsia nested-PCR targeting the variable domain of gltA showed Rickettsia felis in four mosquito species of 16 provinces Cx. pipiens pallens (1.8%, 29/1620); Ae. albopictus (1.2%, 10/806); An. sinensis (1.2%, 2/168); and Ar. subalbatus (2.1%, 8/377). Rickettsia bellii was also widespread, occurring in 12 provinces and 2 species: Cx. pipiens pallens (4.3%, 69/1620) and An. sinensis (0.6%, 1/168). R. felis and R. bellii were found in almost similar numbers in female [1.5% (27/1809) and 1.2% (21/1809), respectively] as in male mosquitoes [1.8% (22/1242) and 4.0% (49/1242), respectively]. Our results indicated that mosquitoes in China are widely infected with R. felis, the agent of human flea-borne spotted fever, and that R. bellii can also occur outside of the Americas and its usual tick hosts.

First report of Rickettsia felis in mosquitoes, USA

“…Although found in a wide range of arthropods including fleas, ticks, mites, and lice, the cat flea (Ctenocephalides felis) is currently believed to be the most likely primary vector of R. felis. There is growing evidence, however, that mosquitoes might be involved in R. felis transmission with the organism having been identified in a wide variety of mosquitoes in Africa and China [1,2]; mouse-model experiments have indicated transmission of R. felis by Anopheles gambiae [3]; there is an association between malaria and fleaborne spotted fever cases in Africa [2]. Although R. felis has been demonstrated in a variety of mammals and arthropods in the USA, there is only one study on its presence in mosquitoes [4].…”

“…The mosquitoes were identified morphologically and with a PCR targeting the mitochondrial cytochrome c oxidase subunit [5] before being pooled (n = 57; 4 to14 per pool) according to species, sex, trap number and collection site. After washing (once in PBS for one minute; once in 70% ethanol for ten minutes; four times, one minute each, in sterile PBS) to remove surface contaminants, DNA was extracted for three previously published and validated PCRs, a gltA-based FRET-PCR [3], a nested-PCR targeting the gltA of Rickettsia [3], and a R. felis species-specific BioB-based PCR [4], which were performed to test for the presence of Rickettsia DNA in mosquitoes. (Figure 1).…”

Identification of Rickettsia felis DNA in the blood of domestic cats and dogs in the USA

“…Three previously validated quantitative PCR assays, mainly a gltA-based Rickettsia FRET-PCR [26], a nested-PCR targeting the gltA of Rickettsia [26], and a R. felis species-specific BioB-based PCR [27], were used to detect Rickettsia DNA in the samples. To optimize the sensitivity of our testing and the relatively small amount of sample DNA available to us, we initially screened 10 µL of each DNA sample with the highly sensitive Rickettsia FRET-qPCR.…”

Mosquito-Borne Diseases Emergence/Resurgence and How to Effectively Control It Biologically

“…Different pathogenic alpha-proteobacteria, including Anaplasma spp., Ehrlichia spp., Candidatus Neoehrlichia, Bartonella spp., and Rickettsia spp., have been identified (xeno-monitoring studies) in adult mosquitoes [59,60]. More interestingly, the agent of febrile rickettsiosis, Rickettsia felis, has not only been identified in mosquitoes [58,61] but also shown to be potentially transmitted by Anopheles mosquitoes in laboratory experiments [62]. Francisella tularensis [63] is also carried by mosquitoes (Aedes), which act as a main vector in Sweden and Finland, making it the first reported mosquito-borne bacterium [63].…”

“…Pathogens 2020, 9, x FOR PEER REVIEW 3 of 25 Different pathogenic blood-borne bacteria are regularly detected in mosquitoes [58,59]. It is not yet clear whether the presence of these bacteria in mosquitoes may be explained by occasional ingestion with blood meals or acquisition from the environment, or whether these bacteria may multiply and eventually be transmitted during blood meals.…”