Rocky Mountain spotted fever (RMSF), caused by Rickettsia rickettsii, is among the most dangerous infectious diseases in the Americas. The disease attacks endothelial cells, leading to extensive microvascular damage throughout the body. Fluid leakage caused by systemic vessel damage creates rashes and edema alongside multiple severe complications, which include pneumonitis, myocarditis, kidney damage, and meningoencephalitis. Advanced RMSF can cause respiratory distress, cardiac abnormalities, coma, and peripheral gangrene, sometimes necessitating amputation if untreated.
The mortality statistics for RMSF show significant diversity because Latin American cases of the disease result in death rates equivalent to those observed in Ebola patients. The urgency for rapid diagnosis and prompt treatment becomes vital because death can occur during the initial eight days of illness for 50% of patients.
The transmission of RMSF occurs through tick species belonging to four distinct genera that include more than nine different species. RMSF remains endemic in Canada, the United States, Mexico, and several countries in South America. RMSF outbreaks have increased since the late 20th century, with urban epidemics emerging in the 21st century.
Brown dog ticks (Rhipicephalus sanguineus sl) are essential for RMSF transmission in Mexico because of their considerable dog population. The disease impacts dogs by causing fever and lethargy in addition to vomiting and limb swelling, resulting in several severe health problems. Brazilian RMSF transmission occurs through the combination of stray dogs and Amblyomma aureolatum ticks, whereas Amblyomma sculptum ticks that feed on capybaras found in urban parks are responsible for elevated RMSF case rates specifically within São Paulo.
An analysis employing One Health methods has divided RMSF into three main ecological zones according to its transmission mechanisms. Sylvatic RMSF consists of natural transmission between wild mammals that rely on the tick vectors Dermacentor spp. in North America alongside Amblyomma spp. and Dermacentor nitens in Latin America.
The disease spreads peridomestically in impoverished regions, where dogs and other domestic animals serve as the main host population. The transmission pattern can be seen in Arizona, Mexico, and Brazil due to their large populations of free-roaming dogs sustaining high tick populations, which consist of Rhipicephalus sanguineus and Amblyomma aureolatum. Lack of proper veterinary healthcare and inadequate tick prevention in certain communities facilitates the continued spread of RMSF.
Urban RMSF cases have emerged as hyperendemic outbreaks within major cities, including São Paulo Mexicali and San José in recent years. Brazilian capybaras now serve as essential agents for RMSF transmission through their role as hosts for Amblyomma sculptum ticks within urban areas. Rhipicephalus sanguineus ticks and stray dogs in Mexico have been responsible for multiple outbreaks throughout the country. The fast spread of RMSF occurs due to poor sanitation, limited healthcare access, and population density in affected areas.
Human actions that disturb natural environments through deforestation, urbanization, and animal population disruptions become essential factors that produce RMSF cases. Data-driven strategies based on vector control and improved animal management programs combined with community health initiatives need implementation to control RMSF transmission.
The number of capybaras corresponds directly to the tick population levels. The most effective control strategies focus on sterilization and fence installation to limit human-tick interactions instead of culling because quick population growth follows.
The brown dog tick, also known as Rhipicephalus sanguineus sensu lato, poses substantial control challenges because it demonstrates resistance to various acaricides and successfully resurfaces in areas it has left. The control measures involve using oral isoxazolines combined with tick collars and integrated pest management strategies, including fixing cracks, managing pastures, and utilizing environmental barriers, but demand ongoing maintenance.
The combination of rapid diagnosis with immediate antibiotic administration sharply decreases mortality statistics. Enhanced public awareness and education about the disease enable quicker identification of RMSF cases and better treatment results.
RMSF remains an extensive public healthcare burden throughout the American continent. Strategic control of this disease needs a unified approach that combines both animal wildlife management and population control of ticks with full-scale public awareness initiatives. Reducing the disease burden and preventing future outbreaks require sustainable solutions that center on fertility control, vector management, vaccination programs, and early treatment education. RMSF cases remain on the rise, particularly in urban areas, thus requiring immediate coordinated interventions to minimize disease-related damages.
References: Foley J, López-Pérez AM, Álvarez-Hernández G, et al. A wolf at the door: the ecology, epidemiology, and emergence of community- and urban-level Rocky Mountain spotted fever in the Americas. Am J Vet Res. 2025;86(3):368-378. doi:10.2460/ajvr.24.11.0368
