[Drop off rhythm of Rhipicephalus sanguineus (Acari: Ixodidae) of artificially infested dogs].

The present study evaluated the drop-off rhythm of Rhipicephalus sanguineus (Latreille) ticks from two populations from Brazil, one from Monte Negro, state of Rondônia, and another from Belo Horizonte, state of Minas Gerais. Artificial infestations with ticks were performed on dogs in the laboratory, held in a light: scotophase regimen of 12:12 h. Larval drop-off rhythm was characterized by similar number of engorged larvae detaching during both periods of light and scotophase, or by a larger number of larvae detaching during the light period.

Allopatric speciation in ticks: genetic and reproductive divergence between geographic strains of Rhipicephalus (Boophilus) microplus.

Background: The cattle tick, Rhipicephalus (Boophilus) microplus, economically impact cattle industry in tropical and subtropical regions of the world. The morphological and genetic differences among R. microplus strains have been documented in the literature, suggesting that biogeographical and ecological separation may have resulted in boophilid ticks from America/Africa and those from Australia being different species.

Redescription of the female, description of the male, and several new records of Amblyomma parkeri (Acari: Ixodidae), a South American tick species.

The tick Amblyomma parkeri Fonseca and Aragão was described in 1952, based on female and immature ticks collected in the states of São Paulo and Santa Catarina, Brazil. Thereafter, there has been no further report of A. parkeri, and the male has remained unknown.

Rocky Mountain spotted fever in dogs, Brazil.

Clinical illness caused by Rickettsia rickettsii in dogs has been reported solely in the United States. We report 2 natural clinical cases of Rocky Mountain spotted fever in dogs in Brazil. Each case was confirmed by seroconversion and molecular analysis and resolved after doxycycline therapy.

Ecological aspects of the free-living ticks (Acari: Ixodidae) on animal trails within Atlantic rainforest in south-eastern Brazil.

In a recent ecological study of the ticks on animal trails within an area of Atlantic rainforest in south-eastern Brazil, Amblyomma aureolatum, A. brasiliense, A. incisum, A.

Experimental infection of capybaras Hydrochoerus hydrochaeris by Rickettsia rickettsii and evaluation of the transmission of the infection to ticks Amblyomma cajennense.

The present study evaluated the infection of capybaras (Hydrochoerus hydrochaeris) by Rickettsia rickettsii and their role as amplifier hosts for horizontal transmission of R. rickettsii to Amblyomma cajennense ticks. Two groups of two capybaras each were evaluated: on day 0, group 1 (G1) was infested by R.

Biology and life cycle of Amblyomma incisum (Acari: Ixodidae).

Amblyomma incisum Neumann is a major tick species in the Atlantic Forest of Brazil. Tapir is the main host for adult ticks and a high aggressiveness of nymphs to humans has been reported. In this work data on the biology and life cycle of this tick species is presented for the first time.

Diagnoses of and illustrated key to the species of Ixodes Latreille, 1795 (Acari: Ixodidae) from Brazil.

The current Brazilian Ixodes fauna is composed of the following eight species: I. amarali Fonseca, 1935; I. aragaoi Fonseca, 1935; I.

Tick-borne rickettsioses in America: unanswered questions and emerging diseases.

During most of the 20th century, Rickettsia rickettsii, the agent of Rocky Mountain spotted fever, was considered the only tick-borne rickettsia associated with human diseases in the Americas. This dogma suggested that the other characterized and noncharacterized rickettsiae isolated from ticks were not pathogenic to humans. This concept has been modified extensively in the past 10 years with the identification of at least three additional rickettsial species that cause human tick-borne rickettsioses and that are prevalent in the Americas, including Rickettsia parkeri, Rickettsia massiliae, and Rickettsia africae.

Experimental infection of the rabbit tick, Haemaphysalis leporispalustris, with the bacterium Rickettsia rickettsii, and comparative biology of infected and uninfected tick lineages.

The present study consisted of two experiments that evaluated experimental infections of Haemaphysalis leporispalustris ticks by a Brazilian strain of Rickettsia rickettsii, and their effect on tick biology. In experiment I, ticks were exposed to R. rickettsii during the larval, nymphal or adult stages by feeding on rabbits (Oryctolagus cuniculus) needle-inoculated with R.

Comparative susceptibility of larval stages of Amblyomma aureolatum, Amblyomma cajennense, and Rhipicephalus sanguineus to infection by Rickettsia rickettsii.

The current study compared the susceptibility of larval stages of Amblyomma cajennense (F.), Amblyomma aureolatum (Pallas), and Rhipicephalus sanguineus (Latreille) to infection by a Brazilian strain of Rickettsia rickettsii. Guinea pigs experimentally infected by R.

Rickettsial spotted fever in capoeirão village, Itabira, Minas Gerais, Brazil.

The present study investigated the infection by spotted fever rickettsia in an endemic area for Brazilian spotted fever (BSF; caused by Rickettsia rickettsii) in Minas Gerais State, Brazil. Human, canine and equine sera samples, and Amblyomma cajennense adult ticks collected in a rural area of Itabira City, Minas Gerais State were tested for rickettsial infection. Through Immunofluorescence Assay (IFA) we demonstrated the presence of antibodies anti-R.

New epidemiological data on Brazilian spotted fever in an endemic area of the state of São Paulo, Brazil.

The present work evaluated rickettsial infection in dogs and their ticks in an area endemic for Brazilian spotted fever (BSF) in the metropolitan area of São Paulo, Brazil, where the tick Amblyomma aureolatum was presumed to be the vector of the disease. Ticks were collected on dogs from 185 houses, encompassing single infestations by Rhipicephalus sanguineus, Amblyomma aureolatum, Amblyomma longirostre, or Amblyomma sp. in dogs from 60 (32.

Prevalence of Rickettsia species antibodies and Rickettsia species DNA in the blood of cats with and without fever.

Rickettsia species antibodies have been detected in some cats but it is unknown whether infected cats develop clinical signs. The prevalence of Rickettsia species deoxyribonucleic acid (DNA) in blood from clinically ill cats has not been determined. The objective of this study was to determine if cats with fever (body temperature >or=102.

Biological parameters of ticks (Amblyomma cajennense Fabricius, 1787) under field and laboratory conditions in Pedro Leopoldo, State of Minas Gerais, Brazil.

This study evaluated the biological parameters of the duration of the pre-oviposition and egg incubation periods and maximum survival of unfed larvae, under field and laboratory conditions, with the aim of providing support for more rational measures for controlling Amblyomma cajennense. This study was conducted at the Experimental Farm of the Veterinary School of the Federal University of Minas Gerais. Every 14 days, from September 1997 to March 1998 and from October 1998 to April 1999, six netted tubes containing engorged females were kept on pasture of Brachiaria decumbens that was up to 60 cm high and another six were kept in a BOD glass chamber (27 degrees C, 80% relative humidity).

Ticks (Acari: Ixodidae) infesting wild birds in an Atlantic forest area in the state of São Paulo, Brazil, with isolation of rickettsia from the tick Amblyomma longirostre.

During field work in Nazaré Paulista, state of São Paulo, Brazil, we found 13 (56.5%) of 23 birds (mostly Passeriformes) to be infested by 28 larvae and 1 nymph of Amblyomma spp. Two larvae were reared to the adult stage, being taxonomically identified as Amblyomma parkeri Fonseca and Aragio, whereas five larvae and one nymph were identified as Amblyomma longirostre Koch.

Canine infection by rickettsiae and ehrlichiae in southern Brazil.

This study evaluated the infection caused by Rickettsia and Ehrlichia agents among dogs in southern Brazil. A total of 389 dogs were tested by the indirect immunofluorescence assay (IFA) for Rickettsia rickettsii, Rickettsia parkeri, Rickettsia amblyommii, Rickettsia rhipicephali, Rickettsia bellii, and Ehrlichia canis. Overall, 42.

In vitro isolation and molecular characterization of an Ehrlichia canis strain from São Paulo, Brazil.

An Ehrlichia canis isolate was obtained from an naturally infected dog exhibiting clinical signs of ehrlichiosis in São Paulo Municipality, state of São Paulo, Brazil. The isolate was characterized by PCR and DNA sequencing of portions of the ehrlichial genes dsb, 16SrRNA, and p28. Partial dsb and 16S rRNA sequences were identical to three and five other E.

New reports of Antricola guglielmonei and Antricola delacruzi in Brazil, and a description of a new argasid species (Acari).

Adults of 3 tick species (Acari: Argasidae) identified as Antricola guglielmonei, Antricola delacruzi, and Carios rondoniensis n. sp. were collected on bat guano in a cave in the state of Rondônia, western Amazon, Brazil.

Observations on Antricola ticks: small nymphs feed on mammalian hosts and have a salivary gland structure similar to ixodid ticks.

Ticks use bloodmeals as a source of nutrients and energy to molt and survive until the next meal and to oviposit, in the case of females. However, only the larvae of some tick species are known to feed upon bats; females are obligatorily autogenous, and nymphal stages are believed to not feed. We investigated the presence of blood in a natural population of nymphal Antricola delacruzi ticks collected from bat guano; their ability to feed upon laboratory hosts; and the microscopic structure of both salivary glands and gut.

The effect of temperature and fasting period on the viability of free-living females of Rhipicephalus sanguineus (Acari: Ixodidae) under laboratory conditions.

Little is known about the effect of temperature on viability of free-living phases of the life cycle of Rhipicephalus sanguineus (Latreille, 1806) despite of its importance as vector of several pathogens. Knowledge of the effect of abiotic factors on the capacity of a given tick species to infest new hosts is important for routine experimental activities under laboratory conditions, and may be relevant to understand the transmission of pathogens. The study evaluates the viability of R.