Conferencias Magistrales. Ehrlichiosis y anaplasmosis humanas en América. Human Ehrlichiosis and Anaplasmosis in America. J. Stephen Dumler. Entre ellas, existen seis especies que causan infecciones en humanos, incluyendo Ehrlichia chaffeensis, agente responsable de la Ehrlichiosis Monocítica. No Brasil, estudos sorológicos e moleculares têm avaliado a ocorrência de espécies de Ehrlichia em cães, gatos, animais selvagens e seres humanos.

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Ehrlichiosis is a disease caused by rickettsial organisms belonging to the genus Ehrlichia. In Brazil, molecular and serological studies have evaluated the occurrence of Ehrlichia species in dogs, cats, wild animals and humans. Ehrlichia canis is the main species found in dogs in Brazil, although E. Ehrlichia chaffeensis DNA has been detected and characterized in mash deer, whereas E.

Canine monocytic ehrlichiosis caused by E. Ehrlichia canis DNA also has been detected and molecularly characterized in three domestic cats, and antibodies against E. There is serological evidence suggesting the occurrence of human ehrlichiosis in Brazil but its etiologic agent has not yet been established. Improved molecular diagnostic resources for eyrlichiosis testing will allow better identification and characterization of ehrlichial organisms associated with human ehrlichiosis in Brazil.

O DNA de E. Ehrlichia are Gram-negative, pleomorphic, obligate intracellular bacteria that infect ehrlihciosis wide range of mammals. The genus initially included 10 species classified based on the host cell infected: The remaining organisms were ehrlicyiosis into the Anaplasma genus: The organisms not currently belonging to the genus Ehrlichia will not be further discussed in this review.

The organism was first described in dogs by Donatien and Letosquard in Algeria. Ehrlichia organisms are mainly transmitted through the bite of an infected tick.

Thus, the presence of known competent tick vectors as well as reservoir hosts largely determine where ehrlichiosis is found. Other tick species, such as A. Several methods with varying degrees of sensitivity and specificity can be used to detect Ehrlichia organisms.

Unfortunately, this technique lacks sensitivity and specificity. Although this technique is still widely used, a significant number of false positives may occur due to cross-reactivity with other organisms from the genera Ehrlichia, Anaplasma and Neorickettsia RISTIC et al.

Several other serological tests are now commercially available to diagnose ehrlichiosis e. Diagnostic accuracy has been greatly enhanced by the introduction of culture and molecular techniques.

These organisms can all be grown in cell culture with exception of E. However, this is a time-consuming technique not available in many laboratories. Cultures also require specialized laboratory facilities and highly trained personnel. The geographic distribution of some Ehrlichia species has not yet been fully established, although E.

Ehrlichiosis is widely detected across Brazil Figure 3. Three species have been described to date in Brazil: This is a review of recent studies on the occurrence of Ehrlichia species in domestic and wild animals, ticks and humans in Ehrrlichiosis. Clinical findings of Ehrlichia canis infection in dogs.

Ehrlichiosis in Brazil

Canine monocytic ehrlichiosis CME is a disease caused by E. The acute stage lasts two to four weeks and has non-specific clinical signs that may include apathy, anorexia, vomiting, fever, ocular and nasal discharge, weight loss, ocular lesions, lymphadenopathy, hepatosplenomegaly, and dyspnea MOREIRA et al.


Cardiomyocyte injury has been identified in Brazilian dogs naturally infected with E. In this population, dogs with acute ehrlichiosis were at a higher risk of developing myocardial cell injury than other sick dogs DINIZ et al.

The subclinical phase usually starts 6 to 9 weeks post-infection. In chronic cases, infected dogs fail ehrlkchiosis mount an effective immune response. It appears that CME occurs at any time throughout the year in many parts of Brazil.

Tropical weather favors the proliferation of its main biological vector R. Although the disease is currently described nationwide, prevalence data is only available for some regions Table 1. The studies ehrlicuiosis with respect to population, geographic area, presence of vector, and diagnostic test used. Therefore, comparison of epidemiological data among studies is diffi;cult or not feasible.

IFA and other serological methods may yield false-positive results because these techniques do not differentiate between infection and previous exposure to the organism, whereas false-negatives by PCR in peripheral blood also may occur in subclinically or chronically infected dogs.

The prevalence of E. Table 1 summarizes the occurrence of E. Using nested-PCR, only 7. It is important to notice that since these studies were conducted in a hospital population, prevalence data may not reflect ehrlkchiosis actual situation of canine ehrlichiosis in that region. A national erhlichiosis of E. The geographical distribution of Ehrlichia spp. Risk factors of Ehrlichia canis infection in dogs. Eighty-seven out of The groups at higher risk of being seropositive to ehrlichiosis than the general population included: Dogs seropositive for B.

In another study using thrombocytopenia and anemia as screeners for E.

At the Botucatu VTH, Southeastern Brazil, canine blood samples randomly obtained from routine tests made at the Clinical Pathology Laboratory were divided into two groups based on platelet count: This population has an unexpectedly high prevalence of thrombocytopenia but unfortunately the randomization method was not described in the study. In this study the authors suggested that in endemic areas dogs with severe thrombocytopenia are more likely to be infected by E.

In the city of Jaboticabal, Southeastern Humanps, 51 dogs with uveitis tested positive to E. Anemia and thrombocytopenia were the most common hematological abnormalities found. A high association between clinical uveitis and positive serology for E. A high prevalence of seropositive dogs Ehrlichia canis prevalence in this study ranged from In a survey conducted in urban areas of Minas Gerais State, blood samples were collected from 51 dogs that were restricted to house backyards and 50 dogs that lived in apartments.

Diagnostic sensitivity between cytological methods was assessed in 50 dogs naturally infected by E. Using 35 samples collected from dogs suspected of being infected with E. Moreover, 51 blood samples from dogs with both clinical signs consistent with ehrlichilsis and the presence of intracytoplasmatic inclusion bodies or morulae-like forms hmanos white enrlichiosis cells were submitted to molecular analysis.


These same dogs were also positive by a second PCR assay targeting a fragment of the ehrlichial dsb humaanos. Four animals had anemia and one of them also had thrombocytopenia. This was the first study to provide evidence of canine infection caused by E. The first humnos detection of E. Further studies are needed to better characterize the Ehrlichia spp. In the United States, white-tailed deer Odocoileus virginianus is considered the main reservoir of E. Two out of three positive E.

Ehrlichia ruminantium infection in ruminants has been reported only in Africa and Caribbean region. Some non-African cervids are also known to be susceptible to this agent, including the whitetailed deer, the Timor deer Cervus timorensis and chital Axis axis PETER et al.

Recently, an Ehrlichia sp. To date, there are no reports of other Ehrlichia species rather than E. Since IFA has high cross-reactivity with members of Anaplasmataceae family, definitive diagnosis of E.

In another study, 72 blood samples from wild captive felids 9 pumas [ P.

Ehrlichiodis positive samples were submitted to another omp-1 gene based nested-PCR and only four samples tested positive.

However, based on omp-1 sequences, Ehrlichia sp. It was the first study of molecular detection of Ehrlichia sp. There are to date two recognized diseases caused by Ehrlichia species: Other rickettsial agents, A.

The lack of molecular characterization of the organism precludes any conclusion regarding the pathogenic agent in these cases. The genetic sequence from this isolate was identical to E. Infestations by the brown dog tick, R. Thus, interaction between human beings and R. Ehrlichia ewingiian agent known to cause granulocytic ehrlichiosis in dogs, was recognized in to cause infections in humans BULLER et al. Human exposure to tick vectors is seasonal and occurs predominantly in rural and suburban areas involving recreational, peridomestic, occupational, and military activities DEMMA et al.

Both forms of human ehrlichiosis monocytic and granulocytic have common clinical and laboratory manifestations that include fever, headache, myalgia and malaise, thrombocytopenia, leukopenia, and elevated liver enzymes OLANO et al. The key for HME or HGE diagnosis is the identification uhmanos fever and thrombocytopenia, leukopenia, and elevated serum alanine-amino transferase in a patient exposed to ticks in endemic areas during times of tick activity STONE et al.

The disease was first thought to be caused by the canine pathogen E.

Ehrlichiosis monocítica humana

The first study using IFA was carried out in for E. Ebrlichiosis had fever, headache, nausea, vomiting, myalgia, conjunctivitis, respiratory and renal failure. However, IFA detected antibodies against E. The second patient was a year-old man presenting similar clinical signs. Antibodies were detected against E. Based on clinical and serologic results a suggestive diagnosis of HME was established. Nine of 1.