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PubMed2001

[Geographical divisions of rat transmissible diseases].

In order to prevent rat transmissible diseases, it is necessary to know the geographical distribution of rats, their external parasitic arthropod and rat-borne disease in human, and to make a graph of geographical division. Stratified sampling was conducted by county to capture rats, and to sort out flea for identification of their genus and species. A total of 55,064 rats sorting as 6 families, 17 genera and 21 species were captured, and a total of 34,733 flea sorting as 4 families, 25 genera and 53 species were picked. Three kinds of rat-borne diseases, namely plague, leptospirosis and epidemic hemorrhagic fever have been occurred and epidemic in Shanxi Province. Following the general principles for geographical division, Shanxi Province was divided into 4 sub-regions: (1) basin among mountains and prairie in Yanbei; (2) loess plateau, hill and prairie with shrub in the west; (3) hill, shrub and basin, prairie with forest in the middle part; (4) hill, basin with forest and prairie in the southeast. When bubonic plague was epidemic, its transmissible mode was probably Meriones meridianus--Xenopsylla conformis--Mus musculus, Rattus norvegicus--Xenopsylla cheoopis--human. Bubonic plague has been occurred within Xingxian and Linxian conxian counties of the second sub-region. Leptospirosis has been occurred in Xiangfen county of the third sub-region, the source of infection was from pigs instead of rats. Epidemic hemorrhagic fever has been occurred in the third and fourth sub-regions, the source of infection was mainly from Ruttus norvegicus.

Animals↗
PubMed2001

Utilizing image processing techniques to compute herbivory.

Leafy spurge (Euphorbia esula L. sensu lato) is a perennial weed species common to the north-central United States and southern Canada. The plant is a foreign species toxic to cattle. Spurge infestation can reduce cattle carrying capacity by 50 to 75 percent [1]. University of Wyoming Entomology doctoral candidate Vonny Barlow is conducting research in the area of biological control of leafy spurge via the Aphthona nigriscutis Foudras flea beetle. He is addressing the question of variability within leafy spurge and its potential impact on flea beetle herbivory. One component of Barlow's research consists of measuring the herbivory of leafy spurge plant specimens after introducing adult beetles. Herbivory is the degree of consumption of the plant's leaves and was measured in two different manners. First, Barlow assigned each consumed plant specimen a visual rank from 1 to 5. Second, image processing techniques were applied to "before" and "after" images of each plant specimen in an attempt to more accurately quantify herbivory. Standardized techniques were used to acquire images before and after beetles were allowed to feed on plants for a period of 12 days. Matlab was used as the image processing tool. The image processing algorithm allowed the user to crop the portion of the "before" image containing only plant foliage. Then Matlab cropped the "after" image with the same dimensions, converted the images from RGB to grayscale. The grayscale image was converted to binary based on a user defined threshold value. Finally, herbivory was computed based on the number of black pixels in the "before" and "after" images. The image processing results were mixed. Although, this image processing technique depends on user input and non-ideal images, the data is useful to Barlow's research and offers insight into better imaging systems and processing algorithms.

Algorithms↗
PubMed2001

Cat-scratch disease: epidemiology, aetiology and treatment.

Cat-scratch disease (CSD) is a clinical syndrome that usually presents as a self-limiting lymphadenopathy associated with a cat scratch or bite. Commonly affecting children and young adults, it has a worldwide distribution. In temperate climates, higher rates are reported in the autumn and winter, which can be attributed to the seasonal breeding of the domestic cat. The organism responsible was identified in 1983, having eluded detection for 50 years. Initially, Afipia felis was thought to be the cause; however, subsequent study failed to confirm a link. During the 1990s, it was demonstrated conclusively that Rochalimaea henselae, later reclassified as Bartonella henselae, was the cause of CSD. B. henselae has been isolated from bacteraemic cats, with transmission among cats thought to be via the cat flea. Although other Bartonella species are transmitted by arthropod vectors, it is unlikely that the cat flea is involved directly in human infection, but plays a role in amplifying the reservoir. B. henselae is difficult to culture, and either serology or the polymerase chain reaction are considered to be the best methods of detection. Genetic variation occurs amongst B. henselae strains, perhaps explaining the inconsistency of some diagnostic techniques. A separate serogroup (Marseilles) has been reported in a seronegative patient with CSD, and B. clarridgeiae has the potential to cause the disease. Atypical presentation is seen in up to 25% of cases, and manifests itself as ocular involvement, encephalopathy, granulomatous hepatitis, hepatosplenic infection, endocarditis and osteomyelitis. The majority of CSD cases resolve spontaneously and do not require antibiotic treatment. In complicated CSD, treatment with trimethoprim-sulphamethoxazole, ciprofloxacin or azithromycin is recommended, with gentamicin being reserved for the severely ill patient.

Animals↗
PubMed1994

[The plague in Finland in 1710].

In the autumn of 1710 Helsinki was struck by the so-called oriental plague during four months. The infection was transferred by black rats which harboured fleas. The flea-bites caused boils. It was believed that the plague was air-borne, and the air was very humid that autumn. Big fires were lit in order to reduce the humidity, the purpose being to make it easier for the infected to breathe. Attempts were also made to dissect the boils. The carriers of the contamination came as refugees from Estland over the Gulf of Finland. The infection had spread from Turkey to Poland and Balticum after the defeat of the Finnish-Swedish army in the summer of 1709 at Poltava in Ucraine. Helsingfors (Helsinki) was struck extremely hard. About two-thirds of the inhabitants died of the pestilence. Some escaped by fleeing to the countryside. The plague spread through the country as far north as to Uleåborg (Oulu) and Cajana (Kajaani). Marketplaces became important centres of infection. With the advent of the frost in December the plague dwindled. At that time Helsinki was practically a dead town.

Disease Outbreaks↗
PubMed2001

Monospecific helminth and arthropod infections in an urban population of brown rats from Doha, Qatar.

Parasitic infections were studied for the first time in an urban population of brown rats (Rattus norvegicus) from Doha. Only one species of helminth was found, the cestode Hymenolepis diminuta, and one ectoparasite, the flea Xenopsylla astia, from a sample size of 136 rats (52 males and 84 females). The prevalence of H. diminuta was 17.6%, increasing with host age but not in relation to host sex nor season of capture. Host age was a key factor in influencing abundance of infection, although there was a significant three-way interaction with season and host sex arising through heavy infections in juvenile male rats in the summer. The prevalence of X. astia was 45.6%, although both prevalence and abundance of infestations were season and host age dependent. In the winter prevalence and abundance were similar in both host age and sex groups, but in the summer both parameters of infestation were markedly higher among juveniles compared with adults. We found evidence for some association between these two species: H. diminuta was more prevalent among rats with fleas than among those without, although this association was season-, and independently sex- and age-dependent. There were no quantitative interactions and reasons for this are discussed in relation to the foraging and breeding behaviour of the brown rat in Qatar.

Animals↗
PubMedDate not supplied

Reaction of freshwater phyto- and zooplankton to pesticides.

The reaction of plankton to the toxic effect of pesticides is considered at four levels: the cell, the organism, the population, and the biocenosis. The basis for the methodological approach to evaluation of response at the cell level was the principle of phase reactions. Depending on concentration, the pesticides may either suppress or stimulate the plankton organisms. Temperature may be decisive intoxic effects (pesticides are effective in a range of 15 to 25 degrees C). Most pesticides having algacidal activity are effective in a range of concentrations of 1-10 mg/liter. Phytoplankton as a whole has a high buffer capacity with respect to pesticides. Changes in ratios of basic components of phytoplankton effected by pesticides most often lead to a change of the dominant. Analogical changes are characteristic also for zooplankton; pesticides lead to the elimination of water fleas from its composition. The stimulating effect of a low concentration of pesticides, changes in the functional activity of the components of bacterial plankton, and changes coupled with this in biogeochemical cycles of nitrogen and phosphorous as well as elimination of water fleas from the plankton promotes the development of "secondary" eutrophication, that is, an increase in the biomass of the phytoplankton.

Animals↗
PubMed2002

Household papular urticaria.

BACKGROUND: Papular urticaria often occurs after bites of insects such as mosquitoes, sandflies, bed bugs and fleas. Multiple bites and local pruritus are characteristic symptoms. Treatment is usually symptomatic and includes antihistamines and corticosteroids. The reappearance of the symptoms can be prevented by successful control of the parasite. OBJECTIVES: To find the causative agent of papular urticaria in afflicted households with involvement of numerous family members, all in a narrow geographic area. PATIENTS: We describe the cases of 20 patients belonging to seven families, who presented to the local primary clinic, suffering from papular urticaria. RESULTS: The cat flea, Ctenocephalides felis, was the hematophagous insect responsible for all infestations. The pruritus and the papular urticaria were treated symptomatically with calamine lotion, topical corticosteroids or oral antihistamines. All clinical symptoms disappeared within a few weeks after effective control of the parasites by spraying and fumigating the infested locations. CONCLUSIONS: Thorough investigation--including, at times, environmental inspection--is necessary to reach the rewarding discovery of the etiology of household papular urticaria. This condition may arise in other environments of similar character.

Adult↗
PubMed2002

[Yersinia pestis as a dangerous biological weapon].

Plague is an infectious disease caused by the Yersinia pestis microorganism, which is transmitted to the human host from a natural reservoir (different rodent species) by a flea bite. Plague is still encountered in humans in the areas of its enzootic prevalence in local rodent populations. Infection by flea bite results in a bubonic or septicemic plague, possibly complicated by secondary pneumonia. The person with pneumonic symptoms may be a source of a droplet-borne inhalatory infection for other people who consequently develop primary pneumonic plague. Despite a clinical form, plague is a severe infection characterized by a short incubation period, rapid onset and quick progress with mortality exceeding 50% if not treated properly. The pneumonic plague is associated with a particularly rapid progress and the mortality rate of almost 100% if not treated properly. As Yersinia pestis can be easily obtained and cultured and is highly pathogenic for humans, it poses a serious threat of being used for bioterrorism purposes. Artificially created aerosol containing plague bacilli can cause numerous and almost simultaneous cases of primary pulmonic plague in an exposed population. Persons exposed would most likely develop severe pneumonia with rapidly progressing respiratory and circulatory failure. The use of the Yersinia pestis strains resistant to antibiotics typically applied cannot be excluded.

Animals↗
PubMedDate not supplied

[Structure and seasonal dynamics of the biotic community ectoparasites of the bank vole in the Il'men'-Volkhov lowland].

A biodiversity, seasonal dynamics and parasite load of a single individual and local population of the bank vole (Clethrionomys glareolus) were studied in coniferous and mixed forests of the Ilmen-Volkhov lowland (neighborhood of Oskuy village, Chudovo region, Novgorod Province) in the period from June 1999 till May 2002. The Gero's traps were used for collecting the host. Lines of traps stood in each place during 3-5 days and were checked twice a day. Trapping of micromammalian hosts and collecting of parasites took place each month, except a few gaps. Total number of collected animals 2854 including 1405 bank voles. The 29 ectoparasite species were recorded on the bank vole in the area of study. Among some mites and fleas a few species are accidental parasites probably accepted by voles from other species of animals. In the Oskuy area, the bank voles are the main and additional hosts of 25 ectoparasite species: fleas--8, lice--1, ixodid ticks--2, gamasid mites--7, acariform mites 7. Species composition of ectoparasites, their occurrence and abundance change during the year. Seasonal changes of abundance and occurrence indices are most expressed in the temporary ectoparasites (ixodid ticks, chiggers, gamasid mites), while in the permanent parasites (lice, acariform mites: Myobiidae, Myocoptidae, Listrophoridae), the seasonal fluctuations of indices are displayed in a less scale. Most vole specimens were infected with this or that ectoparasite species. The parasitocenosis on an individual specimen usually included less than 10 species of the total number 29 species recorded on the bank vole in the area investigated. One ectoparasite species was recorded on 21% of host specimens, 2-5 ectoparasite species were found on 71% of host individuals. Maximal number of ectoparasite species (10 species) was registered on one specimen only. The parasite load was dispersed unevenly among the infected voles. Mean number of parasites of all species on a host individual varied from 124 to 295. The highest grade of parasites (237-297 parasite specimens) was found in the voles with 7-10 species of parasites.

Animals↗
PubMedDate not supplied

[Ectoparasites of the zokor Myospalax myospalax (Rodentia) in northern Altaĭ].

Following ectoparasites have been recorded on the zokor in the Northern Altay: specific fleas--Ctenophthalmus dilatatus, Rhadinopsylla ioffi, Brachyctenonotus myospalacis; a flea distributed on various rodents; ixodid ticks--Ixodes crenulatus, I. persulcatus; gamasid mites--Hirstionyssus myosplalacis. The C. dilatatus carried hypopi of acaroid mites.

Animals↗
PubMed2002

Allergens causing atopic diseases in canine.

Canine atopic skin disease is seasonal or sometimes non-seasonal immune-mediated skin disease which occurs commonly in Korea. The definite clinical sign is systemic pruritus, especially on periocular parts, external ear, interdigit spaces and lateral flank. For diagnosis of this dermatitis, complete history taking followed by intradermal skin test and serum in vitro IgE test needs to be performed. Allergen selection for the diagnosis and treatment of atopic dermatitis should be varied geographically. In this study, with intradermal skin test(IDST) the prevalence of atopic disease and what allergens are involved in are researched. Allergens used for IDST included 26 allergen extracts from six allergen groups: grasses, trees, weeds, molds, epidermal allergens and environmental allergens. The number of allergens was 42 in which the positive and negative controls are included. The most common positive allergen reaction was the house dust mites on IDST(22/35, 63%). The other positive allergen reactions were to flea(3/35, 9%), molds(1/35, 3%), house dusts(2/35, 6%), feathers (1/35, 3%), cedar/juniper(1/35, 3%), timothy grass(1/35, 3%) and dandelion(1/35, 3%). In this study, the most prevalent allergen causing atopic dermatitis in dogs in Korea was the house dust mites followed by the flea.

Allergens↗
PubMed1953

Plague in Africa from 1935 to 1949; a survey of wild rodents in African territories.

The history of plague in Africa during the period 1935-49 is reviewed. Much of the information derives from a questionnaire sent to all African territories in 1950. The annual incidence of plague in Africa declined, particularly from 1946 onwards. In 1949, under 400 cases were reported, as compared with over 6,000 in 1935. By the end of 1949, plague was still active in the Belgian Congo, Kenya and Tanganyika, Madagascar, and southern Africa. No cases were reported from Egypt, Tunisia, Algeria, Morocco, Senegal, or Uganda during 1949. A comparison of the seasonal incidence of plague with prevailing atmospheric conditions (temperature and rainfall) in African territories shows that human plague is more frequent in warm moist weather-60 degrees -80 degrees F (15 degrees -27 degrees C)-than in hot dry, or cold, weather-over 80 degrees F (27 degrees C) or under 60 degrees F (15 degrees C). The highlands of equatorial Africa and of Madagascar appear to provide the optimum environment for the persistence of plague on the domestic (murine) plane and the high-veld and Kalahari of southern Africa on the sylvatic plane. The rat (Rattus rattus) and the multimammate mouse (R. (Mastomys) natalensis) and their fleas Xenopsylla brasiliensis and X. cheopis appear to be mainly responsible for the persistence of the reservoir in the East African highlands; R. rattus and X. cheopis play this role in Madagascar. The gerbils (Tatera and Desmodillus) and their burrow fleas X. philoxera and X. piriei are the main reservoirs of plague in southern Africa. Within these areas, Pasteurella pestis finds an environment suitable for its continued survival; the conditions seem to be comparable to those defined as obtaining in endemic centres in India. Elsewhere in Africa such endemic centres do not appear to exist.

Africa↗
PubMedDate not supplied

[Structure and seasonal dynamics of an ectoparasite community on the common shrew (Sorex araneus) in the Il'men'-Volkhov lowland].

Species composition, seasonal dynamics, and a load of ectoparasites per individual and population of the common shrew Sorex araneus have been examined in coniferous and mixed forests of the Ilmen'-Volkhov lowland (a neighbourhood of Oskuy village, Chudovo district, Novgorod Province) during the period 1999-2003. Trapping of mammals was carried monthly, with exception of few accidental gaps. The Gero traps were used for catching micromammalian hosts. The lines of trap were checked 2 times a day, places of lines changed each 3-5 day. Total number of micromammalians collected during the period of study is 3215, including 1115 specimens of the common shrew S. araneus and 246 ones of the pigmy shrew S. minutus. Parasite fauna on the common shrew included 23 ectoparasite species: fleas--12, ixodid ticks--2, gamasid mites--7, and myobiid mites--2 species. Among recorded species, 9 fleas species and some gamasid species are accidental parasites. These accidental ectoparasite species are common to the bank vole Clethrionomys glareolus in the territory investigated. Species composition, occurrence and abundance indices of parasites changed during the year. In total, about 55% shrew specimens are infected with ectoparasites. The infracommunity of ectoparasites on the common shrew usually consists of 6 species or less. Mean number of all ectoparasite individuals per one host specimens varies from 4 to 83. The greatest number of parasites (50 and 83) was recorded on the shrews, which carried 5 and 4 parasites species, respectively. Biodiversity of parasite species in the ectoparasite community on the common shrew and the load of parasites per one host specimen are lower than those in the bank vole. In forest biotopes explored, the most part of temporary ectoparasite species found on the common shrew was also recorded on other small mammals, which could have contacts with this host. It is possible to conclude that among the parasite supracommunity in the explored ecosystem, the temporary ectoparasites represent a "fond" of temporary parasites, which are common for most small mammal species. A role of different shrew and rodent species as main of additional hosts changes depending on a population density of potential mammalian hosts and other environment factors.

Animals↗
PubMed1978

[Several principles for epidemiologic evaluation of individual regions of the Trans-Caucasian plains-piedmont natural focus of plague].

The authors analyse many-year data concerning the epizootological study of seven landscape-geographical regions of the Eastern Transcaucasus differing by natural conditions and the enzootic intensity. Quantitative assessment of natural nidality determined by the level (norm) of many-year indices calculated for the years of 1955--1974 are presented for each region. Flea vectors were more numerous in localities of stable enzootic manifestation; also the numbers of Meriones erythrourus (carrier rodent) was more stable than in the regions of temporary occurrence of the causative agent and those free of plague. Many-year level of the flea (X. conformis) abundance index equal to one served as the threshold value determining the territory enzooticity.

Animals↗
PubMed2005

Seasonal variation of tungiasis in an endemic community.

Tungiasis (caused by the sand flea Tunga penetrans) is hyperendemic in many resource-poor communities in Brazil. To understand transmission dynamics of this parasitic skin disease in a typical endemic area, a longitudinal study was carried out in a slum in Fortaleza in northeastern Brazil. In a door-to-door survey, the population of a randomly selected area (n = 1,460) was examined on four occasions for the presence of embedded sand fleas. Prevalence rates were 33.6% in March (rainy season), 23.8% in June (end of the rainy season), 54.4% in September (peak of the dry season), and 16.8% in January (begin of the rainy season). Tungiasis was more common in males than in females. The intensity of infestation was correlated with the prevalence. The study shows that prevalence of tungiasis and parasite burden vary significantly during the year with a peak in the dry season. These findings have important consequences for the design of control measures.

Adolescent↗
PubMed2005

Bionomics and distribution of species of Hystrichopsylla in Arizona and New Mexico, with a description of Hystrichopsylla dippiei obliqua, n. ssp. (Siphonaptera: Hystrichopsyllidae).

More than 450 specimens of Hystrichopsylla were collected from nests and hosts of species of Microtus, Neotoma, Tamiasciurus, and Peromyscus in Arizona and New Mexico from 1981-2004. A new subspecies, Hystrichopsylla dippiei obliqua, is described and a map illustrating the distribution of the three taxa (Hystrichopsylla dippiei truncata Holland, H. d. obliqua, and H. occidentalis sylvaticus Campos and Stark) occurring in Arizona and New Mexico is provided. Hystrichopsylla. o. sylvaticus is reported in New Mexico for the first time and H. d. truncata is a new record in Rio Aribba County, NM. Relationships of Mexican species are also discussed. These large fleas are seldom collected from the fur of their mammalian hosts (usually singly) but are prevalent in moist nests. The maximum number of the new subspecies collected from a single nest was 54. Dry nests, particularly those that are not subterranean or otherwise protected from desiccation, do not support development of Hystrichopsylla fleas. Minimum elevation at which H. dippiei ssp. is found in Arizona and New Mexico appears to be about 2,100 m.

Altitude↗
PubMed1991

Distribution and incidence of ectoparasites on small mammals in a rainforest belt of southern Nigeria.

A total of 174 small mammalian hosts were trapped in Ekpoma, Bendel State, Nigeria from October, 1986 to September, 1987 and examined for ectoparasites. 108 infested hosts had 10 species of ectoparasites comprising three species of mites (Laelaps (Echinolaelaps) muricola, Laelaps (E.) gigantea and Laelaps (E.) echidninus); two species of ticks (Amblyomma variegatum and Ixodes sp.); two species of fleas (Xenopsylla cheopis and X. braziliensis); and on especies each of sucking lice (Polyplax spinulosa) and subcutaneous larvae of Cordylobia anthropophaga. Rise in seasonal rainfall positively influenced the incidence of C. anthropophaga and adult fleas, but decrease reduced the incidence of ticks, mites and lice. The incidence of parasitic infestation was influenced by age of host, but not by the sex. Ectoparasite distribution was uneven on their hosts.

Animals↗
PubMed1991

Parasitic and phoretic arthropods of sylvatic and commensal white-footed mice (Peromyscus leucopus) in central Tennessee, with notes on Lyme disease.

Sixteen species of parasitic or phoretic arthropods were collected from 56 white-footed mice, Peromyscus leucopus, live-trapped in central Tennessee from April through November 1987. Arthropod infestation was compared for mice taken from sylvatic (woodland) versus commensal (household) habitats. Three species were recorded from hosts in both habitats: the sucking louse Hoplopleura hesperomydis, the flea Epitedia wenmanni, and the laelapid mite Androlaelaps casalis. Twelve of the 13 remaining arthropod species were taken only from mice trapped in woodland whereas the phoretic glycyphagid mite Glycyphagus hypudaei was collected only from commensal mice. Arthropod faunas on commensal hosts clearly were impoverished. The 12 additional arthropod species recorded from the woodland mice consisted of 1 nidicolous beetle, Leptinus orientamericanus; 1 bot, Cuterebra fontinella; 3 fleas, Ctenophthalmus pseudagyrtes, Orchopeas leucopus and Peromyscopsylla scotti; 1 tick, Dermacentor variabilis; 2 mesostigmatid mites, Androlaelaps fahrenholzi and Ornithonyssus bacoti; 3 chiggers, Comatacarus americanus, Euschoengastia peromysci, and Leptotrombidium peromysci; and 1 undescribed pygmephorid mite of the genus Pygmephorus. Two nymphal and 100 larval D. variabilis were examined for spirochetes and found to be uninfected.

Animals↗