Clarithromycin for the treatment of Mediterranean spotted fever

[Rickettsiosis after tick bite: A subtle clinic picture on many occasions, we must be vigilant]

Rickettsia diseases are a group of tick-borne transmitted diseases, classified into 2 large groups: spotted fevers and typhus fevers. In addition, a new condition has been described recently, known as tick-borne lymphadenopathy. A retrospective series is presented of paediatric cases of rickettsia diseases diagnosed in 2013 and 2014. A total of 8 patients were included, of which 2 of them were diagnosed as Mediterranean spotted fever, and 6 as tick-borne lymphadenopathy. Rickettsia slovaca, Rickettsia sibirica mongolitimonae, and Rickettsia massiliae were identified in 3 of them. Aetiology, clinical features and treatment carried out in each of them are described. The interest of these cases is that, although most have a benign course, the high diagnostic suspicion and early treatment seem to be beneficial for its outcome.

An update on the detection and treatment of Rickettsia felis

Rickettsia felis was described as a human pathogen almost two decades ago, and human infection is currently reported in 18 countries in all continents. The distribution of this species is worldwide, determined by the presence of the main arthropod vector, Ctenocephalides felis (Bouché). The list of symptoms, which includes fever, headache, myalgia, and rash, keeps increasing as new cases with unexpected symptoms are described. Moreover, the clinical presentation of R. felis infection can be easily confused with many tropical and nontropical diseases, as well as other rickettsial infections. Although specific laboratory diagnosis and treatment for this flea-borne rickettsiosis are detailed in the scientific literature, it is possible that most human cases are not being diagnosed properly. Furthermore, since the cat flea infests different common domestic animals, contact with humans may be more frequent than reported. In this review, we provide an update on methods for specific detection of human infection by R. felis described in the literature, as well as the treatment prescribed to the patients. Considering advances in molecular detection tools, as well as options for as-yet-unreported isolation of R. felis from patients in cell culture, increased diagnosis and characterization of this emerging pathogen is warranted.

Tick-borne lymphadenopathy: a new infectious disease in children

OBJECTIVE

To describe the epidemiologic and clinical aspects of patients with tick-borne lymphadenopathy (TIBOLA).

PATIENTS AND METHODS

The study included all patients treated in our hospital who presented characteristic clinical signs of TIBOLA consisting in the presence of an inoculation lesion after a tick bite with regional lymphadenopathies. The study was carried out at the "Corporació Parc Taulí" hospital in the city of Sabadell, Barcelona, Spain. The inclusion period was from April 2000 to April 2006. Serology tests were performed for Rickettsia conorii, R. slovaca, and Borrelia burgdorferi. The presence of Rickettsia was assessed by means of polymerase chain reaction (PCR)-restriction fragment length polymorphism (PCR-RFLP) and linear-after-the exponential-PCR in blood, skin biopsy, and ticks from the patients.

RESULTS

Thirty-six patients fulfilled the inclusion criteria. Twenty-eight patients were children. In most cases, infection occurred between the months of October and April. In 34 patients the tick bite was on the scalp. A necrotic eschar surrounded by a perilesional erythematous halo was observed in 29 cases. All patients had painful regional lymphadenopathies. Serology for R. conorii was positive in 8 cases and for R. slovaca in 2. PCR was negative. The tick, identified as Dermacentor marginatus, was studied in 7 patients. Four of the 7 D. marginatus were positive for sequences compatible with R. slovoca as determined by RFLP or DNA sequencing. Thirty-three patients received antibiotic treatment. Progress was satisfactory in all cases.

CONCLUSIONS

TIBOLA is present in Catalonia (Northeastern Spain) mainly in children. Although clinical and epidemiologic manifestations are very specific microbiologic confirmation is difficult.

Tropical rickettsioses

In recent years, a bewildering array of emerging rickettsial pathogens have been described throughout the world, including in the tropics. Here we present an updated overview of scrub typhus, murine typhus, and epidemic typhus. We also present an update on the emerging spotted fever group rickettsioses described in the tropics through 2005, focusing on epidemiologic and clinical data and management.

Tick-borne rickettsioses around the world: emerging diseases challenging old concepts

During most of the 20th century, the epidemiology of tick-borne rickettsioses could be summarized as the occurrence of a single pathogenic rickettsia on each continent. An element of this paradigm suggested that the many other characterized and noncharacterized rickettsiae isolated from ticks were not pathogenic to humans. In this context, it was considered that relatively few tick-borne rickettsiae caused human disease. This concept was modified extensively from 1984 through 2005 by the identification of at least 11 additional rickettsial species or subspecies that cause tick-borne rickettsioses around the world. Of these agents, seven were initially isolated from ticks, often years or decades before a definitive association with human disease was established. We present here the tick-borne rickettsioses described through 2005 and focus on the epidemiological circumstances that have played a role in the emergence of the newly recognized diseases.

Enfermedades producidas por Rickettsia

Species of the genus Rickettsia are small, obligate intracelular, gramnegative bacteria, many of which are considered nowadays a paradigm of emergent pathogens. With the exception of R. prowazekii, they are maintained in the natural environment through a cycle involving different hosts (mainly mammals), and arthropod vectors (in general ticks, and fleas); humans are affected only by incidental transmission due to arthropod bites. The common pathogenesis of these diseases lie on the predominantly infection of endotelial cells, that determines the development of multisistemic small vessel vasculitis, which may affect lungs (interstitial pneumonitis), heart (miopericarditis), skin (rash), central nervous system (meningoencephalitis), as well as liver, and kidneys. They are classified in two groups: spotted-fever group, and typhus group rickettsia. In Spain the most prevalent rickettsioses of both groups are mediterranean spotted fever (caused by R. conorii), and murine typhus (caused by R. typhi), respectively. This review focuses mainly in these two diseases, and also in other rickettsioses of interest due to their recently emergence or reemergence (R. slovaca, R. africae, R. prowazekii, R. felis), or to their high incidence in other areas (R. rickettsii, Orientia tsutsugamushi).