Molecular Confirmation of Rocky Mountain Spotted Fever Epidemic Agent in Mexicali, Mexico

Tinoco-Gracia, Luis; Lomelí, Moisés Rodríguez; Hori-Oshima, Sawako; Stephenson, Nicole; Foley, Janet E.

doi:10.3201/eid2409.171523

Cited by 24 publications

(20 citation statements)

References 12 publications

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“…Amblyomma cajennense is one of the most important vectors of R. rickettsii [17] in South America. This potentially fatal human and canine pathogen is emerging in northern Mexico, where it is associated with the brown dog tick, Rhipicephalus sanguineus [79,80]. Thus, the potential establishment of A .…”

Section: Discussionmentioning

confidence: 99%

Modeling Potential Habitat for Amblyomma Tick Species in California

Pascoe

Marcantonio

Caminade

et al. 2019

Insects

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The Amblyomma genus of ticks comprises species that are aggressive human biters and vectors of pathogens. Numerous species in the genus are undergoing rapid range expansion. Amblyomma ticks have occasionally been introduced into California, but as yet, no established populations have been reported in the state. Because California has high ecological diversity and is a transport hub for potentially parasitized humans and animals, the risk of future Amblyomma establishment may be high. We used ecological niche modeling to predict areas in California suitable for four tick species that pose high risk to humans: Amblyomma americanum, Amblyomma maculatum, Amblyomma cajennense and Amblyomma mixtum. We collected presence data in the Americas for each species from the published literature and online databases. Twenty-three climatic and ecological variables were used in a MaxEnt algorithm to predict the distribution of each species. The minimum temperature of the coldest month was an important predictor for all four species due to high mortality of Amblyomma at low temperatures. Areas in California appear to be ecologically suitable for A. americanum, A. maculatum, and A. cajennense, but not A. mixtum. These findings could inform targeted surveillance prior to an invasion event, to allow mitigation actions to be quickly implemented.

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Section: Discussionmentioning

confidence: 99%

Modeling Potential Habitat for Amblyomma Tick Species in California

Pascoe

Marcantonio

Caminade

et al. 2019

Insects

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“…However, surveillance may reveal very low prevalence of antibodies in dogs and low proportion of Rickettsia-positive ticks [21], possibly due in part to fine spatial scale endemic foci as well as local disease extinction and introduction of disease to new areas. Across Mexicali, there appears to be a higher risk for human cases and seropositive dogs in some neighborhoods on the periphery of the city and in agricultural small towns (ejidos) in the valley that extends to the southeast of the city [21][22][23]. Even though local elevations in tick numbers increase risk, there have been cases of RMSF and documented brown dog tick infestations even in homes without dogs [21].…”

Section: Introductionmentioning

confidence: 99%

An exploratory analysis of demography and movement patterns of dogs: New insights in the ecology of endemic Rocky Mountain-Spotted Fever in Mexicali, Mexico

et al. 2020

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An outbreak of Rocky Mountain spotted fever (RMSF) transmitted by the brown dog tick (Rhipicephalus sanguineus sensu lato) has emerged as a major human and animal health concern in Mexicali, Mexico. Due to high rates of brown dog tick infestation, susceptibility, and association with humans, dogs serve as sentinels and have a key role in the ecology of RMSF. A cross-sectional household questionnaire study was conducted in six rural and urban locations to characterize dog ecology and demography in RMSF high-and low-risk areas of Mexicali. In addition, we tracked movement patterns of 16 dogs using a GPS data logger. Of 253 households, 73% owned dogs, and dog ownership tended to be higher in high-risk areas, with a mean dog:human ratio of 0.43, compared with 0.3 in low-risk areas. Dogs in high-risk areas had higher fecundity and roamed more, but the dog density and numbers of free-roaming dogs were comparable. There was a higher proportion of younger dogs and lower proportion of older dogs in high-risk areas. The high proportion of immunologically naïve puppies in high risk areas could result in a lack of herd immunity leading to a more vulnerable dog and human population. The marked increase of space use of freeroaming dogs in high-risk areas suggests that unrestrained dogs could play an important role in spreading ticks and pathogens. As means to limit RMSF risk, practical changes could include increased efforts for spay-neuter and policies encouraging dog restraint to limit canine roaming and spread of ticks across communities; due to dog density is less impactful such policies may be more useful than restrictions on the number of owned dogs.

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“…The detection of R. parkeri in A. aureolatum and R. sanguineus ticks was of particular concern, because these species proved to be more susceptible to infection and maintenance of rickettsiae than A. sculptum (Labruna et al, 2008). The participation of R. sanguineus as a rickettsial vector in Brazil is speculative; however, this topic demands awareness, since it is known that this tick is associated with transmission of R. conorii in the Mediterranean Basin and R. rickettsii in the USA and Mexico (Demma et al, 2005;Solano-Gallego et al, 2015;Tinoco-Gracia et al, 2018). In addition, human parasitism by the brown dog tick has been established before, particularly under conditions of high population density (Reck et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

Spotted fever group rickettsial infection in dogs and their ticks from domestic–wildlife interface areas in southeastern Brazil

Campos

Cunha

Machado

et al. 2020

Rev. Bras. Parasitol. Vet.

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Rickettsia rickettsii is the causative agent of Brazilian spotted fever (BSF), for which humans and dogs are both susceptible. Dogs are sentinels in serological surveys, however, canine disease is rarely reported. Therefore, we aimed to evaluate natural infection by spotted fever group (SFG) Rickettsia spp. in dogs and ticks collected from domiciles close to forest fragments, featuring domestic–wildlife interface areas. Samples from 115 dogs and 135 ixodids were assessed by polymerase chain reactions (PCR) targeting the gltA gene for Rickettsia spp. and the ompA gene for the SFG rickettsial species. One dog (0.87%; 1/115) was positive for R. rickettsii. This dog presented nonspecific laboratory and clinical abnormalities (thrombocytopenia, hyperproteinemia, lymph node enlargement, emaciation, anorexia, and lethargy). Rickettsia parkeri was identified in 2.96% (4/135) of the ticks (Amblyomma sculptum, A. aureolatum, and Rhipicephalus sanguineus). This study confirmed the presence of SFG bacteria in non-endemic and preserved locations, where domestic and wild populations interact. We reinforce the fact that the dog is susceptible to natural R. rickettsii infection. Although this is a rare finding, preventive measures should be taken against BSF in the studied areas. Finally, R. parkeri infection is possibly being demonstrated in A. sculptum for the first time.

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Molecular Confirmation of Rocky Mountain Spotted Fever Epidemic Agent in Mexicali, Mexico

Cited by 24 publications

References 12 publications

Modeling Potential Habitat for Amblyomma Tick Species in California

Modeling Potential Habitat for Amblyomma Tick Species in California

An exploratory analysis of demography and movement patterns of dogs: New insights in the ecology of endemic Rocky Mountain-Spotted Fever in Mexicali, Mexico

Spotted fever group rickettsial infection in dogs and their ticks from domestic–wildlife interface areas in southeastern Brazil

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