![]() However, various experimental transmission studies suggest that the temperate and tropical lineages do differ in their ability to transmit a variety of other pathogens, including Ehrlichia canis, Hepatozooan canis, and Anaplasma platys. lineages differ in their capacity to transmit R. ![]() bacteria, but to date, only the tropical lineage has been associated with the distribution of RMSF in Mexico. (2021) found both lineages present in northern Mexico, with the tropical lineage widespread throughout the country and the temperate lineage present in Chihuahua and Sonora states. lineages occupy distinct ecological niches, various studies have found both the temperate and tropical groups living in sympatry in central eastern Arizona. While it has been suggested that the two main R. sanguineus species complex, ticks will be referred to in terms of temperate and tropical lineage throughout this text. While the redesignations are acknowledged as valid, given the current transitionary state of the taxonomical status of the R. To date, however, there has been no revision that includes the tropical lineage as described in North America. The aforementioned tropical lineage within the Americas is currently under revision, with specimens from Australia and southern Asia declared a separate species, R. designated a neotype and renewed morphological and molecular descriptions of the species and identified the previously designated temperate lineage as R. turanicus) are minute, further complicating the taxonomic status. lineages (a tropical group and a temperate group) and other Rhipicephalus species (specifically R. Morphological distinctions among the two main recognized R. Historically, a non-specific morphological description and loss of the holotype have led systematists to disagree on how to classify the species complex. The existence of more than one species within this taxon was first recognized by Szabo et al. refers to a complex of 11–17 related species or subspecies with a worldwide distribution. Genetic Variation of Rhipicephalus sanguineus s.l. with RMSF may have important implications for the epidemiology and expansion of this disease to other parts of the world and should be explored in greater detail. Affected communities report a high incidence of free-roaming dogs, which can spread infected ticks among households. Throughout Arizona and northern Mexico, the warm climate and peridomestic habitat provide suitable conditions for the ticks to remain active year-round. ![]() in and around human homes and allows the tick to complete its entire life cycle indoors. The close relationship between domestic dogs and humans enables infestations of R. ![]() ![]() sanguineus s.l., but the ticks will feed on humans as incidental hosts and can transmit R. Delays in seeking health care and the resemblance of symptoms to many other diseases further exacerbate the mortality rate of RMSF in these communities. While the disease is easily treated with antibiotics, it can be fatal if left untreated. Since the first case of locally transmitted RMSF was identified in Arizona in 2003, there have been nearly 500 cases and 28 deaths on six tribal reservations, with a case fatality rate almost 15 times higher than the national rate. Rhipicephalus sanguineus sensu lato-vectored RMSF has been recognized in Mexico since the 1930s, though data on estimated incidence is limited. Most of the reported cases occurred in southeastern states, including North Carolina, South Carolina, Tennessee, Oklahoma, and Arkansas, where the principal vector is Dermacentor variabilis, and Montana, Idaho, and Wyoming, where the principal vector is D. In 2018, the Centers for Disease Control and Prevention (CDC) reported 5544 cases of spotted fever rickettsioses, including RMSF reported in the United States, a twelve-fold increase since the year 2000. Among the most significant of these diseases is Rocky Mountain spotted fever (RMSF), a bacterial infection caused by Rickettsia rickettsii, which kills more people within North America than any other tickborne disease. Ticks (Acari: Ixodida: Ixodidae) are important vectors of many human and animal diseases, especially within North America. ![]()
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