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PubMedDate not supplied

Visceral leishmaniasis in a New York foxhound kennel.

Although endemic throughout much of the world, autochthonous visceral leishmaniasis has been reported on only 3 previous occasions in North America. After diagnosis of visceral leishmaniasis in 4 foxhounds from a kennel in Dutchess County, New York (index kennel), serum and ethylenediamine-tetraacetic acid (EDTA)-anticoagulated blood were collected from the remaining 108 American or cross-bred foxhounds in the index kennel and from 30 Beagles and Basset Hounds that were periodically housed in the index kennel. Samples were analyzed for antibodies to or DNA of tickborne disease pathogens and Leishmania spp. Most dogs had antibodies to Rickettsia spp., Ehrlichia spp., Babesia spp., or some combination of these pathogens but not to Bartonella vinsonii (berkhoffi). However, DNA of rickettsial, ehrlichial, or babesial agents was detected in only 9 dogs. Visceral leishmaniasis was diagnosed in 46 of 112 (41%) foxhounds from the index kennel but was not diagnosed in any of the Beagles and Basset Hounds. A positive Leishmania status was defined by 1 or more of the following criteria: a Leishmania antibody titer > or = 1:64, positive Leishmania polymerase chain reaction (PCR), positive Leishmania culture, or identification of Leishmania amastigotes by cytology or histopathology. The species and zymodeme of Leishmania that infected the foxhounds was determined to be Leishmania infantum MON-1 by isoenzyme electrophoresis. Foxhounds that were > 18 months of age or that had traveled to the southeastern United States were more likely to be diagnosed with visceral leishmaniasis. Transmission of Leishmania spp. in kennel outbreaks may involve exposure to an insect vector, direct transmission, or vertical transmission.

Animals↗
PubMed2002

Rabbit haemorrhagic disease: field epidemiology and the management of wild rabbit populations.

Rabbit haemorrhagic disease (RHD) has become established in wild rabbit populations throughout Western Europe, Australia and New Zealand. The abundance of wild rabbits has been significantly reduced, particularly in drier areas of southern Spain, inland Australia and South Island New Zealand. A detailed knowledge of the epidemiology of RHD is essential for the management of the disease in natural rabbit populations, either to rebuild or to control populations. When RHD first spread among naive wild rabbits, epidemiological studies provided unique information on the rate of spread, the possible role of insect vectors in transmission, and the correlation between the impact of disease on populations and climatic variables. Current research shows a consistent pattern of epidemiology between Europe and Australasia. Typically, the most severe epizootics of RHD occur among young sub-adult rabbits which have lost age-related resilience and maternal antibodies. However, the timing of these outbreaks reflects climatic variables that determine the breeding season of the rabbits and the periods when RHD virus (RDHV) is most likely to persist and spread. Further factors that may complicate epidemiology include the possibility that non-pathogenic RHDV-like viruses are present in natural rabbit populations. Additionally, the question of how the virus persists from year to year remains unresolved; persistence in carrier rabbits is a possibility. Understanding of the epidemiology of RHD is now sufficiently advanced to consider the possibility of manipulating rabbit populations to alter the epidemiological pattern of RHD and thereby maximise or minimise the mortality caused by the disease. Altering the epidemiology of RHD in this manner would assist the management of wild rabbit populations either for conservation or pest control purposes.

Animals↗
PubMed2001

Recent developments in the chemotherapy of Chagas disease.

Chagas disease remains an important health problem in the Americas. Advances are being made in parts of South America in blocking transmission from insect vectors or blood transfusion, but more effective chemotherapy is needed for the millions who are already infected. This is especially important since recent results have indicated that treatment is beneficial for the elimination of the chronic course of the disease. The rational development of new drugs depends on the identification of differences between human metabolism and that of the causative parasite, Trypanosoma cruzi. Recent developments in the study of the basic biochemistry of the parasite have allowed the identification of novel targets for chemotherapy, such as sterol metabolism, protein prenylation, proteases, and phospholipid metabolism, and these are the subject of this review.

Animals↗
PubMed2001

Bisphosphonates as chemotherapeutic agents against trypanosomatid and apicomplexan parasites.

Trypanosomatid and apicomplexan parasites remain an important health problem in developing countries. Advances are being made in parts of the world in blocking transmission from insect vectors, but more effective chemotherapy is urgently needed. This is especially important since development of resistance is a growing problem. The rational development of new drugs depends on the identification of differences between human metabolism and that of the parasites. Recent developments in the study of the basic biochemistry of these parasites have resulted in the discovery that bisphosphonates, drugs widely used in the treatment of benign and malignant diseases characterized by increased bone resorption, could have a role as lead antiparasitic agents.

Animals↗
PubMed1995

In vitro study of the anti-leishmanial activity of biodegradable nanoparticles.

Leishmania are obligate intracellular parasites, responsible for leishmaniasis. Leishmaniasis are transmitted via insect vector to vertebrate hosts including humans. The infection was reproduced in vitro with promastigotes which can infect murine resident peritoneal cells. Amphotericin B was incorporated into poly(D, L-lactide-co-glycolide) nanoparticles, biodegradable drug carriers, to allow specific targeting inside the cell. The interaction of the drug with infected cells was determined by exposing macrophage cultures to drug carriers. The toxic effects of polymeric drug carriers were defined prior to exposing cells to drug-loaded nanoparticles. For contact times up to 4h, cells tolerated polymer concentrations of 0.01%. The viability of parasites after treatment was determined. Infected macrophages were incubated at 26 degrees C (which allows the transformation of amastigote to promastigote) along with loaded and unloaded nanoparticles, as well as the free drug alone, and a count of the parasites in the medium was recorded. Anti-leishmanial activity was observed with drug-free nanoparticles. This activity may arise through the release of hydrogen peroxide following the activation of macrophages. The incorporation of amphotericin B did not enhance this effect. Interestingly, trehalose, a cryoprotector of the freeze-dried nanoparticles, altered parasite growth and activated macrophages.

Amphotericin B↗
PubMed1984

A simple method for experimental infection of phlebotomine sand flies with Leishmania.

Mouse macrophages, grown in continuous cell culture at 37 degrees C, were inoculated with the promastigote stage of various human pathogenic Leishmania species. Under these culture conditions, the parasites rapidly entered the cells and transformed into amastigotes. Two or 3 days after inoculation, the infected macrophages were mixed with washed human erythrocytes and were fed to female sand flies (Phlebotomus papatasi and Lutzomyia longipalpis) through a chick skin membrane. Within 7-10 days after feeding, large numbers of promastigotes were observed in the anterior portion of the insects' guts, indicating that the infected sand flies were capable of transmitting the parasites by bite. This relatively simple and rapid technique should facilitate studies on the biology of Leishmania in their insect vectors. It also eliminates the need for animals as a source of amastigotes.

Animals↗
PubMed1985

Human cutaneous leishmaniasis acquired in Texas.

Four cases of autochthonous human cutaneous leishmaniasis have been identified in south-central Texas since 1980. The patients presented with chronic ulcerating papules on the face, earlobe, and lateral thigh. In two patients, the infections healed without treatment. In the other two patients, the lesions healed following treatment with intramuscular sodium stibogluconate or topical antimony potassium tartrate. Serologic testing of family members, using four different techniques, indicates that asymptomatic infections may occur. These are the first reported cases of cutaneous leishmaniasis acquired in Texas since 1974. Organisms isolated from patients in 1974 and 1980 belonged to the Leishmania mexicana complex when tested by the isoenzyme technique. Although no animal reservoir or insect vector has been identified, six species of sand flies belonging to the genus Lutzomyia do inhibit this part of Texas. Accumulated evidence strongly suggests that cutaneous leishmaniasis is endemic in south-central Texas.

Antibodies↗
PubMed1988

Toxic effects produced or mediated by human eosinophil granule components on Trypanosoma cruzi.

The eosinophil granule major basic protein, the eosinophil cationic protein, and the eosinophil-derived neurotoxin were found to be lytic for Trypanosoma cruzi trypomastigotes from blood, cell cultures, or insect vectors and for cultured amastigotes. The toxic effects of the major basic and cationic proteins were inhibited by the polyanions heparin and dextran sulfate, in keeping with the cationic nature of these proteins, or by heat denaturation, suggesting that molecular conformation was also relevant. The lytic activity of the neurotoxin was not inhibited by heating at 56 degrees C for 4 hr, establishing an additional difference with the eosinophil cationic protein. Heparin had only a slight inhibitory effect on the toxicity of the neurotoxin, and dextran sulfate was inactive even at 25 mg/ml. Although both the eosinophil cationic protein and the neurotoxin possess ribonuclease activity, only the toxicity of the latter was abolished by the ribonuclease inhibitor RNasin (Promega, Madison, Wisconsin) or by a competitive substrate, yeast ribonucleic acid. Eosinophil peroxidase significantly increased the extent of trypomastigote or amastigote killing by hydrogen peroxide in the presence of iodide. This effect was abrogated by sodium azide, bovine serum albumin, or gelatin, known inhibitors of the eosinophil peroxidase + halide + hydrogen peroxide system. These results suggest that the destruction of T. cruzi trypomastigotes and amastigotes by eosinophils may result from toxic mechanisms involving several granule proteins.

Animals↗
PubMed1989

A review of the geographic distribution and epidemiology of leishmaniasis in the New World.

A review of the epidemiologic aspects of the New World leishmaniases, including their known geographic distribution, etiologic agents, zoonotic reservoirs, and insect vectors, based on biological and molecular characterization of Leishmania isolates is presented. Data summarized in this paper on parasite taxonomy and geographic distribution come from our studies of greater than 1,000 New World Leishmania isolates identified by species-specific monoclonal antibodies using an indirect radioimmune binding assay and from scientific literature.

Animals↗
PubMed2001

Impact of canine control on the epidemiology of canine and human visceral leishmaniasis in Brazil.

Brazil is the only country endemic for zoonotic visceral leishmaniasis (ZVL) that regularly conducts epidemiologic and prophylactic control programs that involve the treatment of human cases, insect vector control, and the removal of seropositive infected dogs. This report reviews 60 studies reporting data on the efficacy of these recommended control tools and concludes that in Brazil 1) eradication of the disease in Minas Gerais was achieved by the concomitant use of the three control methods, 2) although seropositivity by an immunofluorescent assay is not completely related to infectiousness, the removal of seropositive dogs leads to a significant reduction of canine and human incidence, 3) improvement of the sensitivity of the diagnostic tool used for canine control should optimize the efficacy of control, and 4) although difficult and expensive, the public health dog control campaigns performed in Brazil reduced the incidence of ZVL and should be maintained since treatment of dogs is an unrealistic intervention, both because of its prohibitive cost and relatively poor effectiveness.

Animals↗
PubMed2001

Probable autochthonous Plasmodium vivax malaria transmission in Michigan: case report and epidemiological investigation.

In September 1995, a Michigan resident with no history of international travel was diagnosed with Plasmodium vivax infection, and local mosquito-borne transmission was suspected. An epidemiological investigation did not identify additional cases of local transmission, and there was no apparent link to the 12 imported malaria cases detected in the region. Potential sites of nighttime outdoor exposure included a campground in a swampy area, close to a racetrack frequented by international travelers, some of whom were known to come from countries with malaria transmission. Entomological investigation identified Anopheles spp. larvae and adults near the campsite. Summer temperatures 4.2 degrees C above average would have contributed to shortened maturation time of P. vivax within the insect vector, increasing the likelihood of infectivity. These investigations indicated that this patient probably acquired P. vivax infection through the bite of a locally infected Anopheles spp. mosquito. Physicians need to consider malaria as a possible cause of unexplained febrile illness, even in the absence of international travel, particularly during the summer months.

Adult↗
PubMed1998

Neural network pattern recognition of photoacoustic FTIR spectra and knowledge-based techniques for detection of mycotoxigenic fungi in food grains.

Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS), a highly sensitive probe of the surfaces of solid substrates, is used to detect toxigenic fungal contamination in corn. Kernels of corn infected with mycotoxigenic fungi, such as Aspergillus flavus, display FTIR-PAS spectra that differ significantly form spectra of uninfected kernels. Photoacoustic infrared spectral features were identified, and an artificial neural network was trained to distinguish contaminated form uncontaminated corn by pattern recognition. Work is in progress to integrate epidemiological information about cereal crop fungal disease into the pattern recognition program to produce a more knowledge-based, and hence more reliable and specific, technique. A model of a hierarchically organized expert system is proposed, using epidemiological factors such as corn variety, plant stress and susceptibility to infection, geographic location, weather, insect vectors, and handling and storage conditions, in addition to the analytical data, to predict Al. flavus and other kinds of toxigenic fungal contamination that might be present in food grains.

Aflatoxins↗
PubMed2001

Interspecific variability of prevalence in blood parasites of adult passerine birds during the breeding season in Alaska.

Blood parasite prevalence based on microscopic examination of stained blood smears was determined in adults of 11 passerine bird species sampled during their breeding season (May and June 1997-98) in interior Alaska (USA). These species included primarily Nearctic migratory species such as the dark-eyed junco (Junco hyemalis) and neotropical migratory species such as the blackpoll warbler (Dendroica striata), alder flycatcher (Empidonax alnorum), Swainson's thrush (Catharus ustulatus), northern waterthrush (Seiurus noveboracensis), and bank swallow (Riparia riparia) as well as one long-distance palearctic migrant, the arctic warbler (Phylloscopus borealis). The more prevalent parasites were Leucocytozoon dubreuili (73% of the sampled turdinids), L. fringillinarum (42% of the sampled fringillids and parulids), and Trypanosoma avium (39% of the sampled hosts). Other parasites (H. fallisi: 18% of the sampled turdinids; Haemoproteus paruli: 14% of the sampled parulids; H. fringillae: 5% of the sampled fringillids; microfilariae: 4% of the sampled hosts) were observed less frequently. Plasmodium vaughani was found only in two yellow warblers (Dendroica petechia). Overall parasite prevalence varied between 0% in the alder flycatcher to >80% in Swainson's thrush, arctic warbler, and Townsend's warbler (Dendroica townsendi). Prevalence of various hematozoa also was bird species-dependent. No relationship was observed between prevalence and either foraging (aerial versus trees/shrubs) or nesting habits (ground versus arboreal) or general location of the wintering area of the different species examined. Prevalence also was unrelated to average dates of arrival on breeding grounds and, therefore, to potential duration of exposure to local insect vectors before capture. Differences in blood parasite prevalence among species breeding in a same region and in the same type of habitat may result from differences in host specificity such as immunological resistance to infection or blood meal preference by potential vectors and/or in behavioral adjustments/physiological traits that alter exposure to vectors.

Alaska↗
PubMed1998

A short history of plant virology. III. The thirties.

The Thirties testified on the outstanding development of plant virology: the new discoveries formalized the concept of virus on a physicochemical background. Plant viruses, which had received their own taxonomical position at the end of the Twenties, were no longer considered as simple "infective pathogens" as their size, shape and chemical nature were determined, particularly for one of them--tobacco mosaic virus (TMV). This paramount contribution was achieved as a consequence of a functional interaction between biology on one side, and chemistry and physics on the other side, from the development of which molecular biology was born. The chemical characterization of TMV developed from the first determination of nitrogen presence in purified virus, performed by Carl Vinson, through the identification of TMV as Wendell Stanley's infective, autoreplicative protein macromolecule, to the final discovery of its nucleoprotein nature by the British group of Frederick Bawden. Thorough analytical techniques--in particular electron microscopy--led to disclose the exact shape and size of TMV particle. These discoveries, that opened a new era of virology, were corroborated by new knowledge that, although less explosive, can be considered of great importance for the development of plant virology. The methodologies to estimate viral activity; the study of the relationships between viruses and insect vectors; the studies on virus spread within plants; the identification of non-sterile type of resistance and of correlation between single plant genes and viral pathogenesis benefited plant virology of a set of knowledge that, together with the discoveries on the physico-chemical properties of TMV, raised plant virology from a secondary branch of plant pathology to a new independent science by itself.

History, 20th Century↗
PubMedDate not supplied

[The epizootiological role of the population organization of the stock of fleas on the long-tailed suslik in a natural focus of plague in Tuva].

Spatial location of epizootic events in the Tuva plague focus is determined at a considerable degree by the population structure of the flea Citellophilus tesquorum--the main plague microbe vector. Within the enzootic territory occupied by five populations of the long-tailed ground squirrel (Citellus undulatus) there are six populations of C. tesquorum. Each population of fleas has a corresponding autonomic plague focus. Various conditions for the microbe life activity in these populations are recovered. The circulation of the microbe is closely connected with certain intrapopulation groupings of fleas--the nuclei of populations.

Animals↗
PubMed1999

RT-PCR and its detection limit for cell culture grown bluetongue virus 1 using NS1 gene group specific primers.

RT-PCR was standardised for the detection of bluetongue viral RNA using highly expressed non structural protein 1 gene as the target gene with specific primers targeted to 274 bp of 5' end of NS1 gene. PCR product was consistently obtained in 30 PCR cycles. Further, detection limit of RT-PCR was estimated using serial 10 fold dilutions of BHK 21 cells grown BTV 1. The study suggested that RT-PCR can be used for detection of BTV in Indian conditions with the sensitivity limit of 10 infectious particles of the virus. The study suggested that this technique may be used as a tool for sensitive detection of BTV in carrier/reservoir animals, insect vectors and certification of animals and their germ- plasm for export and import purposes.

Animals↗
PubMed2001

Hepatocystosis in a baboon (Papio anubis).

A 26-lb wild-caught adult female baboon was obtained from a commercial vendor. Routine tests for parasites, pathogenic bacteria, and tuberculosis were negative throughout the 10-week quarantine. However, routine radiographs performed at the end of the quarantine period detected multiple small radioopaque nodules evenly dispersed throughout the liver. A hepatic biopsy was obtained during routine ovariectomy of the baboon, and a diagnosis of granulomatous hepatitis made. Approximately 1 year after her arrival, the baboon was euthanized for reasons unrelated to the hepatitis. The liver contained multiple (40 to 50) white foci that were 1 to 3 mm in diameter; these foci were visible on the surface as well as throughout the parenchyma. There was multifocal, moderate capsular fibrosis, with adhesions between the hepatic lobes and between the diaphragm and liver. Histologic examination revealed multiple degenerate Hepatocystis sp. merocysts. H. kochi and H. simiae are malarial-type nonpathogenic protozoa endemic to Old World nonhuman primates, including baboons. Infected animals are asymptomatic and do not experience hemolysis. Transmission requires an insect vector, therefore infection with Hepatocystis sp. has minimal implications for colony health. There is no known danger of transmission to humans.

Animals↗