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At least 1,009 records · Page 56Linked to original sources
PubMed1998

A review of heartwater and the threat of introduction of Cowdria ruminantium and Amblyomma spp. ticks to the American mainland.

Heartwater, caused by the rickettsial agent Cowdria ruminantium, is one of the most devastating livestock diseases in sub-Saharan Africa. In addition to domestic cattle, sheep, and goats, a variety of nondomestic species can acquire subclinical and clinical infections. Recent epidemiologic findings that demonstrate a long-term host carrier state in domestic and wild ruminants, intrastadial transmission by the tick vectors (Amblyomma spp.), vertical transmission of the agent from cows to their calves, and the presence of both C. ruminantium and Amblyomma variegatum in the Caribbean suggest that the introduction of this exotic disease to the American mainland is a significant threat. Veterinarians working with wildlife should be familiar with this disease and should follow appropriate preventive measures to minimize the risk of infection in captive and wild populations of ruminants.

Africa↗
PubMed2004

Evidence of rickettsial and leptospira infections in Andean northern Peru.

Between May and October 2002, a cluster of acute febrile illnesses occurred in the subtropical Andean foothills of Peru. Serologic evidence in villages where disease had been documented showed that the prevalence of IgM antibody to Leptospira ranged from 6% to 52%, that of IgM antibody to spotted fever group (SFG) rickettsia ranged from 10% to 19%, and that of IgM antibody to Coxiella burnetii from 1% to 15%. Measurement of IgG antibodies for SFG rickettsiae suggested that this disease was endemic. In contrast, IgG antibodies against C. burnetii were largely absent. In humans, microagglutination tests identified pathogenic variants of Leptospira. The presence of an SFG rickettsial infection was confirmed in four febrile patients following polymerase chain reaction and sequencing of the conserved 17-kD common antigen gene (htrA). Collectively, these analyses indicated that Rickettsia sp., C. burnetii, and Leptospira sp. were circulating in the region during the time of disease outbreak and implicate the involvement of an as yet undetermined SFG rickettsia in northwestern Peru.

Adolescent↗
PubMed2005

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.

Animals↗
PubMed2005

Evidence of Rickettsia spp. infection in Sweden: a clinical, ultrastructural and serological study.

Sweden is an area potentially endemic for spotted fever rickettsioses. Rickettsia helvetica has been isolated from its tick vector Ixodes ricinus, and in a handful of cases linked to human disease. This study demonstrates for the first time in Sweden the transmission of rickettsial infection after a tick bite and the attack rate in an endemic area. We present three cases of documented rickettsial infection and a prospective serological study of Swedish recruits who were trained in the area where the patients lived and showed seroconversion to spotted fever rickettsiae. All patients showed a four-fold increase in antibody titer to the spotted fever rickettsia, R. helvetica, and immunohistochemical examination revealed rickettsia-like organisms in the walls of skin capillaries and veins. Electron microscopy showed organisms resembling R. helvetica and immunogold labeling with two anti-rickettsial antibodies demonstrated specific labeling of the rickettsial organisms in the skin biopsy specimens. Eight of the thirty-five recruits showed a four-fold increase in IgG titer reflecting a high rate of exposure. The results of this study demonstrate that spotted fever rickettsioses should be taken into consideration in the diagnosis of tick-transmitted infections in Sweden.

Aged↗
PubMed1999

IgM antibodies in hospitalized children with febrile illness during an inter-epidemic period of measles, in Somalia.

BACKGROUND: In the context of the measles elimination programme, endorsed by the expanded programme on immunization of the World Health Organization, the identification of infections which may be confused with measles is a major challenge. OBJECTIVE: To determine the causes of febrile illness in children in an inter-epidemic period of measles in a Somalian hospital. STUDY DESIGN: Serological tests were performed on sera from 23 Somali children with febrile illness and from 23 age matched children, to measure the specific IgM and IgG antibodies against measles virus, mumps virus, rubella virus, human herpes-6 virus, Epstein Barr virus, parvovirus B19, dengue virus, Mycoplasma pneumoniae and Rickettsia conorii. RESULTS: In about one third of the cases of febrile illness viral, mycoplasmal and rickettsial agents could be identified serologically as the probable cause of the disease. CONCLUSIONS: Although febrile illness with rash in children needing hospitalization is usually assumed to be due to measles, there are several other important virological causes of this condition which need to be considered in the differential diagnosis. Moreover there is a growing need to develop a simple, sensitive, specific and ready to use test to identify each case of measles, if this disease is to be eliminated.

Antibodies, Bacterial↗
PubMed1999

Cowdria ruminantium infection in ticks in the Kruger National Park.

Adult Amblyomma hebraeum ticks, the principle vector of heartwater (cowdriosis) of domestic ruminants in southern Africa, were collected in pheromone traps placed in Kruger National Park, an exclusively wildlife sanctuary in South Africa. These ticks transmitted Cowdria ruminantium, the rickettsial agent causing heartwater, to a susceptible goat, resulting in acute, fatal disease. C ruminantium was isolated in bovine endothelial cell culture from the plasma of this animal during the febrile stage of the disease and transmitted to susceptible goats, causing fatal heartwater. The prevalence of C ruminantium infection in 292 ticks was determined by polymerase chain reaction (PCR) analysis to be 1.7 per cent (95 per cent confidence interval 0.71 to 4.0 per cent). A DNA probe analysis, which is less sensitive than PCR, detected infection in three of the five PCR-positive ticks. The remaining infections were below the detection limit of the DNA probe, which is approximately 70,000 organisms. This is the first evidence that a vector-wildlife cycle of transmission of C ruminantium can be maintained independently of domestic ruminants.

Animals↗
PubMedDate not supplied

[Morphological manifestations of the intracellular toxic effect of microorganisms of the ornithosis-lymphogranuloma-trachoma group].

Interactions of the causative agents of meningopneumonia and ovine abortion with pulmonary macrophages in experimental infection in white mice were studied by histological, immunofluorescent and electron microscopic methods. The causative agent of meningopneumonia did not multiply in colonies and caused toxic lesions in the cells and formed cytoplasmic oxiphilic inclusion bodies. Being the product of cell degeneration, these oxiphilic inclusion bodies were conducive to long-term survival of the cell and slow release from them of elementary bodies of meningopneumonia agent. The agent of ovine abortion multiplied in colonies without toxic affection of the cells or formation of oxiphilic inclusion bodies. It is suggested that oxiphilic inclusion bodies represent morphological manifestation of the intracellular toxic effect of rickettsial and ornithosis-like agents possessing dissociated (non-colonial) mode of multiplication.

Abortion, Veterinary↗
PubMed1989

Cardiovascular and pulmonary complications of epidemic typhus.

A case of typhus fever associated with cardiac and pulmonary complications is reported. The patient was a 24-year-old Egyptian female with characteristic clinical presentation of rickettsial infection, though no rash was present throughout the course of the disease. We could not find a report of such complications in the English medical literature.

Adult↗
PubMed2002

[Tick-borne neurological diseases].

Some microorganisms transmitted to man via tick bite are responsible for infections, which can be associated with neuro-meningeal complications. TBE virus is the most frequent virus associated with potentially severe neurological lesions. No treatment is available so far. The most frequent bacterial diseases in which neurological complications may appear are Lyme borreliosis, Q fever and some rickettsial infections. More recently ehrlichiosis have emerged as new infections that may be associated with neuro-meningeal complications. Appropriate antibiotic therapy may be used for the treatment of these bacterial infections, but no vaccine is available so far.

Animals↗