Distribution and Occurrence of Amblyomma maculatum sensu lato (Acari: Ixodidae) and Rickettsia parkeri (Rickettsiales: Rickettsiaceae), Arizona and New Mexico, 2017–2019

Abstract

<jats:title>Abstract</jats:title> <jats:p>Amblyomma maculatum Koch sensu lato (s.l.) ticks are the vector of Rickettsia parkeri in Arizona, where nine cases of R. parkeri rickettsiosis have been identified since the initial case in 2014. The current study sought to better define the geographic ranges of the vector and pathogen and to assess the potential public health risk posed by R. parkeri in this region of the southwestern United States. A total of 275 A. maculatum s.l. ticks were collected from 34 locations in four counties in Arizona and one county in New Mexico and screened for DNA of Rickettsia species. Rickettsia parkeri was detected in 20.4% of the ticks, including one specimen collected from New Mexico, the first report of R. parkeri in A. maculatum s.l. from this state. This work demonstrates a broader distribution of A. maculatum s.l. ticks and R. parkeri in the southwestern United States than appreciated previously to suggest that R. parkeri rickettsiosis is underrecognized in this region.</jats:p>

Science abhors a surveillance vacuum: detection of ticks and tick-borne bacteria in southern New Mexico through passive surveillance

“…While R. parkeri has been reported in New Mexico from A. maculatum sensu lato, this is the first report of R. parkeri from Dermacentor spp . in New Mexico [20]. Rickettsia parkeri Black Gap was characterized from a D. parumapertus tick isolate collected in Brewster County, Texas in 2015 and closely related bacteria have been identified in the same tick species from Utah and Arizona in the Western United States and the states of Sonora and Chihuahua in Northern Mexico [48, 49].…”

“…Collection sites ( Fig 1 ) were chosen based on accessibility and encompassed a range of elevation and habitat. We included one location in southwestern NM where A. maculatum had previously been collected [20]. Study areas ranged in elevation from 1,000 m to 2,810 m.…”

“…In 2020, Hecht et al investigated the occurrence of Amblyomma maculatum sensu lato ticks and associated Rickettsia parkeri bacteria in far southwestern New Mexico and reported the first instance of Amblyomma maculatum Koch sensu lato (s.l.) infected with R. parkeri [20]. Most recently, in 2023, Grant et al assessed the distributions and lineages of temperate and tropical Rhipicephalus sanguineus sensu lato within the U.S. and found that the R. sanguineus sensu lato in New Mexico belong to the temperate lineage [21].…”

Phylogenetic Differentiation of Rickettsia parkeri Reveals Broad Dispersal and Distinct Clustering within North American Strains

“…The primary vectors of R. parkeri in North America are the ixodid ticks Amblyomma maculatum Koch sensu stricto (s. s.) in the eastern and Gulf Coast regions of the United States and A. maculatum sensu lato (s. l.) in southern Arizona ( 10 – 12 , 14 , 15 ). Recent field studies further identified R. parkeri sensu stricto (s. s.) in A. maculatum s. l. ticks in West Texas ( 16 ) and New Mexico ( 17 ), as well as in the northern state of Sonora ( 18 ) and the southeastern state of Tabasco, Mexico ( 19 ). In South America, Amblyomma triste Koch and Amblyomma tigrinum Koch, both members of the Amblyomma maculatum tick group ( 20 ), are the primary vectors of R. parkeri s. s. ( 5 , 6 , 21 – 23 ).…”

Association between Growth Rate and Pathogenicity of Spotted Fever Group Rickettsia

“…3,[6][7][8] Since then, additional cases of R. parkeri rickettsiosis have been reported in many southeastern and southwestern regions of the United States. [9][10][11] In addition to the primary vector, A. maculatum, R. parkeri has also been found in different species of ticks, including Amblyomma americanum, [12][13][14] Amblyomma triste, 15 and Ixodes scapularis. 14,16 R. amblyommatis, formerly named Rickettsia amblyommii and 'Candidatus Rickettsia amblyommii', has been detected in A. americanum throughout the United States.…”