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PubMed2005

[Rickettsioses].

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).

Animals↗
PubMed2003

A sero-epidemiological study of Rickettsia typhi infection in dogs from Soria province, central Spain.

Data relating to Rickettsia typhi infection in Spain are scarce. The seroprevalence of canine infection with this species has now been investigated, in dogs from the central province of Soria. The results of indirect immunofluorescence assays indicated that nine (12.3%) of the 73 dogs checked were carrying antibodies against R. typhi. The gender, age and breed of the dog, and whether it was used for hunting, shepherding, guarding or simply as a pet, apparently had no significant affect on the probability of it being seropositive. Being infested with fleas or having a history of such infestation was, however, significantly associated with seropositivity. The present results confirm that dogs may be infected with R. typhi and indicate their potential usefulness as sentinels in epidemiological studies of the pathogen. The results of wide-scale, serological studies of dogs may allow the geographical distribution of R. typhi to be mapped relatively simply.

Animals↗
PubMed2005

Structural features of lipopolysaccharide from Rickettsia typhi: the causative agent of endemic typhus.

Rickettsia typhi causes endemic typhus, a relatively mild, acute febrile illness characterized by headache and macular rash. It is maintained in rodents and transmitted to humans by flea Xenopsylla cheopis. R. typhi contains a lipopolysaccharide thought to display a noticeable antigenic activity. We examined its structural features and it appears that the O-specific chain of the R. typhi LPS is composed mainly of the alternating Glc and QuiNAc residues linked by 1-->4 bonds.

Animals↗
PubMed2002

Geographic association of Rickettsia felis-infected opossums with human murine typhus, Texas.

Application of molecular diagnostic technology in the past 10 years has resulted in the discovery of several new species of pathogenic rickettsiae, including Rickettsia felis. As more sequence information for rickettsial genes has become available, the data have been used to reclassify rickettsial species and to develop new diagnostic tools for analysis of mixed rickettsial pathogens. R. felis has been associated with opossums and their fleas in Texas and California. Because R. felis can cause human illness, we investigated the distribution dynamics in the murine typhus-endemic areas of these two states. The geographic distribution of R. felis-infected opossum populations in two well-established endemic foci overlaps with that of the reported human cases of murine typhus. Descriptive epidemiologic analysis of 1998 human cases in Corpus Christi, Texas, identified disease patterns consistent with studies done in the 1980s. A close geographic association of seropositive opossums (22% R. felis; 8% R. typhi) with human murine typhus cases was also observed.

Adolescent↗
PubMed1984

Experimental infection with Rickettsia mooseri and antibody response of adult and newborn laboratory rats.

Quantitative studies of selected features of peripherally induced Rickettsia mooseri (= R. typhi) infection in Rattus norvegicus-derived white laboratory rats revealed a unique association between microbe and amplifying vertebrate host which appears to be especially conducive to maintenance of the enzootic cycle. Both adult and newborn (1-3 days old) rats were highly susceptible to percutaneous infection (ID50 = approximately 1 organism), but neither showed signs of disease or died even when inoculated with 10(4)-10(5) plaque-forming units. Gain in body weight of infected newborn rats was indistinguishable from that of uninfected newborn rats over the first 3 weeks of life. The course of the systemic infection, as measured by the rise and fall of R. mooseri titers in blood, brain and kidney and the serum antibody response, was almost identical in adult and newborn rats. Thus, despite their immaturity in certain immunological processes, newborn rats controlled postnatal R. mooseri infection about as well as did adult rats. The rickettsemic period of about 10 days corresponds to the period of infectivity of inoculated rats for fleas. Rickettsiae were not isolated from blood, brain or kidneys by methods employed for more than 4-5 weeks after infection. Serum antirickettsial antibodies persisted for at least 60 weeks postinfection, i.e., longer than the usual life span of rats in nature and, hence, are a valid measure of the cumulative experience of rat populations with R. mooseri infection.

Age Factors↗
PubMed1986

Acute febrile cerebrovasculitis: a syndrome of unknown, perhaps rickettsial, cause.

In late 1983, five patients living near Charlottesville, Virginia, were treated for an unusual syndrome of fever, headache, altered mentation, multifocal neurologic signs, and cerebrospinal fluid pleocytosis. Clinical signs of brainstem disease developed in four patients. All five had had recent exposure to forests or wood and contact with flea-infested dogs. Two patients died; one survivor has had recurrent seizures. Brain biopsy samples in two patients and autopsy findings in another showed cerebral vasculitis and perivasculitis involving mostly venules and capillaries. In the autopsy, the severest vascular lesions involved the brainstem and thalami, where they were accompanied by acute fibrinoid necrosis, but discrete vascular lesions of lesser intensity were randomly distributed in the white matter and cortex. Serologic studies on paired specimens in four patients showed significant cross-reacting antibody responses to rickettsial (typhus-group) antigens in the indirect hemagglutination, latex agglutination, and IgM microimmunofluorescence tests, but no agent was visualized or isolated. The cause of this serious inflammatory disorder is unknown.

Acute Disease↗
PubMed2001

Clinical and epidemiological observations regarding the 1998 Kauai murine typhus outbreak.

Five cases of murine typhus occurring on southwestern Kauai in 1998 are described, following an investigation by the Department of Health. Two cases also had concurrent leptospirosis. Recent habitat changes of peridomestic animals and their fleas may have increased the risk for developing murine typhus. Increased suspicion of typhus by island physicians and more aggressive rodent control activities are recommended.

Adult↗
PubMed2002

A returned traveller with persistent fever due to murine typhus.

Murine (endemic) typhus is a notifiable disease in Hong Kong, but its diagnosis can be difficult. We report a case of murine typhus in a middle-aged man who presented with persistent fever, headache, and skin rash 2 weeks after returning from a visit to China. The diagnosis of murine typhus requires a high index of suspicion for a febrile patient with a history of potential exposure to the disease vector (rat flea) in an endemic area. The importance of early recognition lies in the potential for early therapeutic intervention, leading to decreases in morbidity and duration of stay in hospital.

Anti-Bacterial Agents↗
PubMed2003

Seroprevalence of rickettsial infection in commensal rodents and shrews trapped in the Bangkok Metropolitan Area.

Murine typhus and scrub typhus are important human rickettsial diseases in Thailand. Small mammals, including many species of rodents and shrews, serve as the reservoir host of rickettsial diseases. Rickettsia typhi can be transmitted to humans by fleas causing murine typhus, while infection with Orientia tsutsugamushi causing scrub typhus in humans is transmitted by chiggers. The prevalence of rickettsial infection depends on the geographic area. The seroprevalence of antibody to R. typhi and O. tsutsugamushi was studied in commensal rodents and shrews trapped in markets in the Bangkok Metropolitan Area (BMA). R. typhi and O. tsutsugamushi antigen prepared in the yolk sac of embryonated eggs were used to determine the specific antibody in trapped animals' sera by using fluorescein isothiocyanate (FITC)-anti rat immunoglobulins as a second antibody. Antibody to R. typhi was found in 25 (5%) of 500 sera tested and no antibody to O. tsutsugamushi was detected. R. typhi antibody titer ranged from 40-1280 and was found in Rattus norvegicus (4.2%), Rattus rattus (0.4%), Rattus exulans (0.2%), and Mus musculus (0.2%) trapped in 8 of 47 markets in the BMA. R. typhi antibody was commonly found in R. norvegicus. The authors concluded that murine typhus is an important rickettsial disease and R. norvegicus is an important reservoir species of rodents found in markets of the BMA.

Animals↗
PubMed1953

DDT in the prevention of plague in Ecuador.

There was no satisfactory solution to the plague problem until the advent of DDT, which made it possible to break one of the links in the chain of spread of the disease. DDT has been used in Ecuador since 1946 with great success, particularly in the control of rural plague; it is systematically applied every four months in areas considered to be plague foci. Wherever possible, it is used in the form of 10% dusting-powder, although emulsions and solutions of DDT are also used.Since 1950, however, there have been indications, confirmed by experiments and by information from Brazil, that generations of DDT-resistant fleas are breeding. This creates a serious problem requiring close study if a solution is to be found and if one of the most effective weapons for plague-control is not to be rendered useless.

Animals↗
PubMed1993

Murine typhus in Thailand: clinical features, diagnosis and treatment.

One hundred and thirty-seven patients with murine typhus were reviewed. A history of direct contact with rats was rare, and none gave a history of flea bite. No seasonal trend was observed. Clinical presentations included fever (100%), hepatomegaly (24%), rash (20%) and non-specific signs. Complications were uncommon but included jaundice, pneumonia, renal insufficiency and meningitis. Only two patients died. A single 200 mg dose of doxycycline significantly shortened the duration of fever: 79% were afebrile in 48 h, compared to 15% of the untreated group.

Adolescent↗
PubMed1997

[Endemic typhus imported to Norway].

Murine typhus, caused by Rickettsia typhi, is an important zoonosis in all parts of the world. The disease is transmitted from rodents to humans by fleas. In this article we describe the first three cases of serologically proven murine typhus imported into Norway during the 1990s. The patients were Norwegian tourists who had visited respectively Guinea-Bissau, Crete and Thailand. They all became acutely ill with fever, chills and severe headache 1-10 days after return to Norway. None of them had a rash. Two patients were admitted to hospital, and one was treated with ciprofloxacin for suspected typhoid fever. All the patients recovered without sequelae. The diagnosis of murine typhus was based on detection of IgM-anti-bodies against R typhi in serum samples during reconvalescence.

Adult↗
PubMed1980

Infestation by Tunga penetrans.

Infestation by the flea Tunga penetrans, although quite prevalent in Central America, South America, and Africa, is rarely recognized or reported in North America. This report describes a case of tungiasis occurring in a New York resident who acquired the disease in Africa. The patient manifested characteristic lesions of white papules with central black pits on the dorsa of her toes. Treatment consisted of removal of the offending parasites.

Adult↗
PubMed1995

Branch retinal arterial occlusions in multifocal retinitis with optic nerve edema.

OBJECTIVE: To determine the natural history and visual prognosis of patients with branch retinal arterial occlusions secondary to multifocal retinitis. METHODS: Cases were reviewed for seven patients who exhibited multifocal retinitis and branch retinal arterial occlusion. The average age of the patients was 27 years (age range, 14 to 19 years). RESULTS: Six patients had systemic illnesses associated with their ocular findings. Four patients were scratched by a cat or exposed to a cat with fleas within 1 month of symptoms. Three of these patients were tested and had positive cat-scratch disease titers. At presentation, five patients complained of a scotoma, and two noted blurred vision. On examination, visual acuity was 20/25 or better in all but one eye. Five patients had vitritis, which was bilateral in three. Four patients exhibited optic nerve edema, which was bilateral in two. White intraretinal infiltrates were present in all patients, and were bilateral in five. The six patients who were examined within 1 week of symptoms had a white retinal infiltrate at the site of vascular occlusion. The retinal findings resolved in 2 to 6 weeks and did not recur. The final visual acuity was 20/20 OU in all patients. CONCLUSIONS: Branch retinal arterial occlusions represent a complication of multifocal retinitis and idiopathic optic nerve edema. The arterial occlusions are probably caused by a focus of retinitis. This self-limited disorder has an excellent visual prognosis and may be related to cat-scratch disease.

Adolescent↗
PubMed1996

Activity of novel juvenoids on arthropods of veterinary importance.

Different juvenile hormone mimics were compared regarding their efficacy against larval and pupal stages of the diptera Aedes aegypti, Musca domestica, and Lucilia cuprina as well as the cat flea Ctenocephalides felis. Structure-activity relationship of a series of new diphenylethers was analyzed and compared to juvenoids like methoprene, hydroprene, and fenoxycarb. Selected compounds were taken for a competition binding assay and their effect on JH-degradation by esterases was examined. The results indicate that neither high affinity to JH-binding proteins nor interference with JH breakdown are responsible for the extraordinary efficacy of the diphenylethers investigated. Two superior diphenylethers, however, proved to be more resistant to UV-radiation than methoprene.

Aedes↗
PubMed2001

Health evaluation of translocated free-ranging primates in French Guiana.

Among over 40 mammal species threatened by the filling of a hydroelectric dam reservoir in French Guiana, three species of primates have been translocated, comprising 124 red howler monkeys, six white-faced sakis, and 95 golden-handed tamarins. Health status of the animals was evaluated by direct physical examination and by hematological, biochemical, virological, and parasitological surveys of collected blood. The physical condition of the howlers was slightly worse toward the end of the capture period, but that of sakis and tamarins remained satisfactory. Several ectoparasites (ticks, larvae of dipterous insects, fleas, and lice) were collected, and various wounds, apparently nondebilitating, were recorded in howlers. Hematological and biochemical profiles determined for the three species revealed a slight anemia in howlers. Entamoeba, Strongyloides, and Trypanoxyurus were common in fecal samples of howlers. A survey of blood smears from the three species revealed infection by several types of microfilaria, Trypanosoma rangeli-like and Plasmodium brasilianum in all three, and Trypanosoma cruzi-like in howlers. These infections had no significant impact on the health status or the hematological profiles. Serologic investigations revealed occasional reactions against Toxoplasma gondii, a strong anti-Plasmodium response in the two Cebidae species, and a weaker one in tamarins. Attempts to isolate arbovirus failed, but antibody responses to Mayaro and yellow fever viruses were strong, especially in the howlers. A strong correlation between age and serological status led to a better understanding of the epidemic cycles. Our survey indicates French Guianan primates are reservoirs for several anthropozoonoses, including malaria, Chagas disease, and arboviruses.

Animal Diseases↗
PubMed1986

Acute toxicity of brass particles to Daphnia magna.

The aquatic toxicity of brass particles was examined. Acute, 48 hour bioassays were performed using the water flea, Daphnia magna. Tests were conducted with uniform suspensions of uncoated brass particles, brass particles coated with a Teflon solution, silica particles, and titanium dioxide particles. The Teflon coating solution and the supernatant of the brass suspension (after settling of the brass) also were tested. All tests were conducted according to guidelines set forth by the US Environmental Protection Agency and the Organization for Economic Cooperation and Development. Mean EC50 determinations of 20.0 micrograms l-1 and 23.6 micrograms l-1 were calculated for uncoated brass particles and coated brass particles, respectively. The silica, titanium dioxide, and Teflon each had an EC50 greater than 1 g l-1. Chemical fate studies demonstrated that the brass dissociated to its ionic components of copper and zinc quickly at pH 2.0. At pH 5.0 and 6.5, the dissociation occurred too slowly to account for the observed toxicity. The data suggested that the toxicity is due to filtration by the daphnids and subsequent ingestion. EC50 determinations for the brass particles are nearly identical with published EC50 values for copper salts.

Alloys↗
PubMed2005

Phytochemical phenolics in organically grown vegetables.

Fruit and vegetable intake is inversely correlated with risks for several chronic diseases in humans. Phytochemicals, and in particular, phenolic compounds, present in plant foods may be partly responsible for these health benefits through a variety of mechanisms. Since environmental factors play a role in a plant's production of secondary metabolites, it was hypothesized that an organic agricultural production system would increase phenolic levels. Cultivars of leaf lettuce, collards, and pac choi were grown either on organically certified plots or on adjacent conventional plots. Nine prominent phenolic agents were quantified by HPLC, including phenolic acids (e. g. caffeic acid and gallic acid) and aglycone or glycoside flavonoids (e. g. apigenin, kaempferol, luteolin, and quercetin). Statistically, we did not find significant higher levels of phenolic agents in lettuce and collard samples grown organically. The total phenolic content of organic pac choi samples as measured by the Folin-Ciocalteu assay, however, was significantly higher than conventional samples (p < 0.01), and seemed to be associated with a greater attack the plants in organic plots by flea beetles. These results indicated that although organic production method alone did not enhance biosynthesis of phytochemicals in lettuce and collards, the organic system provided an increased opportunity for insect attack, resulting in a higher level of total phenolic agents in pac choi.

Acids, Carbocyclic↗