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The first fatal Rickettsia rickettsii infection was diagnosed in the southwest of Mexico. The patient had fever, erythematous rash, abdominal pain, and severe central nervous system involvement with convulsive crisis. The diagnosis of R. rickettsii infection was established by immunohistochemistry and specific polymerase chain reaction.

The aim of this study was to provide information of the occurrence of Rickettsia felis in wild mammals from three municipalities in Yucatan, Mexico. The reactivity of rodent serum to Rickettsia antigens was detected in 80.9% (17 of 21) samples using immunofluorescence assay. Polymerase chain reaction identified rickettsial DNA in spleens of 43.5% (10 of 23) rodents and 57.1% (4 of 7) opossums. The identification of the rickettsial DNA was confirmed as R. felis by restriction fragment length polymorphism and DNA sequencing. This study comprises the first report of R. felis detection in wild mammals in Yucatan.

The first human case of infection caused by Rickettsia in Yucatan was detected in 1996, and it was determined that the species was R. felis. Since then, passive epidemiologic surveillance was implemented to search for human cases in the public hospitals of the state, and in 2005, the first human case of Rocky Mountain spotted fever was detected. During the following 2 years, eight new confirmed cases and one probable case were identified. Seven cases involved children younger than 12 years of age, with a fatal outcome in three of the cases. Children are a particularly vulnerable population for this serious emerging infection.

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Rickettsia akari is the causative agent of rickettsialpox, a primarily urban mite-borne rickettsiosis that is encountered in the United States and in a few countries around the world. Its vector is the mite Liponyssoides sanguineus, which is found on rats and mice, which serve as reservoirs for the disease. In this work we report a severe animal case of R. akari infection with two unusual features: R. akari was found in a dog, and its potential vector was a tick.

Rickettsia typhi is the causal agent of murine typhus; a worldwide zoonotic and vector-borne infectious disease, commonly associated with the presence of domestic and wild rodents. Human cases of murine typhus in the state of Yucatán are frequent. However, there is no evidence of the presence of Rickettsia typhi in mammals or vectors in Yucatán. The presence of Rickettsia in rodents and their ectoparasites was evaluated in a small municipality of Yucatán using the conventional polymerase chain reaction technique and sequencing. The study only identified the presence of Rickettsia typhi in blood samples obtained from Rattus rattus and it reported, for the first time, the presence of R. felis in the flea Polygenis odiosus collected from Ototylomys phyllotis rodent. Additionally, Rickettsia felis was detected in the ectoparasite Ctenocephalides felis fleas parasitizing the wild rodent Peromyscus yucatanicus. This study’s results contributed to a better knowledge of Rickettsia epidemiology in Yucatán.