Borreliae in larval Ixodes ricinus ticks.
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Animals↗
Biomedical subjects
Z Hubálek
Publications and source records attributed to Z Hubálek.
Salmonellae in gulls and other free-living birds in the Czech Republic.
Cloacal swabs, collected from 756 wild synanthropic and exoanthropic birds of 57 species in the Czech Republic, yielded 32 strains of Salmonella typhimurium [phage types (PT) 141, 104 and 41], six isolates of S. enteritidis (PT 8, 4 and 6e), and one each of S. panama and S. anatum. Except for one S. enteritidis isolate from a grey-lag goose (Anser anser) and one S. typhimurium isolate from a coot (Fulica atra), all of the other strains were derived from black-headed gulls (Larus ridibundus), of which 24.7% were found to be infected. The black-headed gull might play a role in the dispersal of pathogenic salmonellae.
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Effect of pH on the stability of type-C toxin of Clostridium botulinum.
Stability of type-C botulinum toxin at pH 1.8-12.0 and during exposure to 5 and 28 degrees C for 20 and 16 h, respectively, was tested by titration on adult mice. The toxin was found in the samples kept at pH of 2.7-10.2, whereas, at the pH extremes of 1.8 and 12.0, it was inactivated.
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Probability models of the rate of infection with tick-borne encephalitis virus in Ixodes persulcatus ticks.
A total of 3,254 adults of Ixodes persulcatus tick were collected in a taiga forest habitat situated in the Amgun river basin (Khabarovsk region, the Far East, USSR) and examined individually for the presence and amount of tick-borne encephalitis virus. The over-all proportion of infected ticks was 6.6% and it varied between 3.4% and 9.4% in the years 1982 to 1985. The amount of virus per tick was approximated by the gamma distribution determining a probability that the number of plaque-forming units (PFU) per tick is not greater than a selected value. The frequency distribution of infected ticks followed a model of the negative binomial distribution, enabling the estimation of probability of the occurrence of a given number of infected ticks in the area. However, the parameters of both probability models (i.e., the PFU content per tick, and the frequency of infected ticks) varied for particular years.
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A comparison of the occurrence of borreliae in nymphal and adult Ixodes ricinus ticks.
The prevalence of borreliae in 209 nymphal and 251 adult Ixodes ricinus was investigated in two areas of southern Moravia, Czechoslovakia, using the dark-field and the Giemsa stained-smear techniques. The proportions of infected ticks were 3.8% in nymphs and 10.6% in adults of area A, while they were 29.1% in nymphs and 35.9% in adults of area B. The mean number of borreliae per tick was about 3 to 10 times greater in adult than in nymphal I. ricinus. The results indicate a significant role of nymphal I. ricinus in the ecology of Borrelia burgdorferi and in the epidemiology and epizootiology of Lyme borreliosis.
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Persistence of Clostridium botulinum type C toxin in blow fly (Calliphoridae) larvae as a possible cause of avian botulism in spring.
Diverse samples were examined at a site of water-bird mortality, caused by Clostridium botulinum type C toxin in southern Moravia (Czechoslovakia). The toxin was detected in high concentrations in mute swan (Cygnus olor) carcasses (less than or equal to 1 x 10(6) LD50/g) as well as in necrophagous larvae and pupae of the blow flies Lucilia sericata and Calliphora vomitoria (less than or equal to 1 x 10(5) LD50/g) collected from them. It was detected in lower concentrations (less than or equal to 1 x 10(3) LD50/g) in other invertebrates (ptychopterid fly larvae, leeches, sow-bugs) associated with these carcasses, and occasionally in water samples (8 LD50/ml) close to the carrion. The toxin was not detected in the samples of water, mud or invertebrates collected at a distance greater than or equal to 5 m from the carcasses. The toxin-bearing larvae of L. sericata and C. vomitoria, containing 80,000 LD50/g of type C toxin, were exposed in the mud at the study site for 131 days from November to March. Although the toxin activity decreased 25-fold and 40-fold in the two samples of maggots exposed during this period, it remained very high (less than or equal to 3,200 LD50/g). Birds ingesting a relatively low number of these toxic larvae (or pupae) in the spring could receive a lethal dose of the toxin.
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Isolation of Tahyna virus from biting midges (Diptera, Ceratopogonidae) in Czecho-Slovakia.
A total of 14,250 haematophagous biting midges (genus Culicoides, Diptera: Ceratopogonidae) were collected in June 1986 in the mountains Ceskomoravská vysocina (about 600 m above sea level); from these 2 strains of Tahyna virus (serogroup California, Bunyaviridae) were isolated. To our knowledge this is the first isolation of a California serogroup virus from the species of family Ceratopogonidae as well as the first report of arbovirus isolation from biting midges in Europe.
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[Botulism in birds living in an aquatic environment in Nové Mlýny in the Breclav District].
Epizootic of wild water birds caused by the toxin Clostridium botulinum of C type occurred in extensive shallow artificial lakes of the Nové Mlýny dam system from May to October 1988 and later on from February to early April 1989. In total more than 3,000 dead or dying birds of 44 species were found, the following orders were prevailing: Anseriformes (56%), Lariformes (33%), Charadriiformes (6%) and Ralliformes (4%). Botulotoxin was detected at high concentrations in sarcophagic fly larvae of Calliphora vomitoria and Lucilia sericata which were collected in bird cadavers, but it was not found in different components of the aquatic environment (water, submersed vegetation, phytoplankton, zooplankton, Gastropoda, Crustacea, Oligochaeta, larvae of Odonata, Chironomidae and Ceratopogonidae). Future development of the epizootic situation in the Nové Mlýny artificial lakes will depend on the water level and meterological conditions in the critical period (May to September).
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Hantaviruses in small wild living mammals in Czechoslovakia. Results of a 1983-1989 study.
During a 7- year period were hunted small wild living mammals and examined by ELISA and RIA techniques for the presence of hantavirus antigen and/or antibodies by MFA. In total 3,050 animals of 16 species caught in 9 out of 10 regions of Czechoslovakia, were examined. The proportion of positive animals was 4.4%. To the positive ones with the serotype 2 (Western type) belonged the following: M. arvalis, C. glareolus, P. subterraneus, A. sylvaticus, A. flavicollis. To the Eastern serotype: A. agrarius in eastern Slovakia, A. flavicollis in North of Bohemia and A. sylvaticus in South of Moravia. The repeatedly examined localities were found to be either repeatedly positive or repeatedly negative. The antigen titres in the lungs of M. arvalis were constant irrespective of sex and season of capture. They were, however, much higher in young animals, whereas the proportion of positivities was higher in adults ones. The titres of antigen in the lungs of C. glareolus never exceeded those of M. arvalis.
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Isolation and characterization of Sedlec virus, a new bunyavirus from birds.
A pathogenic agent designated AV 172 was isolated from the blood of a Reed Warbler (Acrocephalus scirpaceus) out of 767 samples from birds belonging to 35 species and 14 families. The birds (largely wetland passerines) were captured in the reed-belt littoral of Nesyt fishpond in southern Moravia, Czechoslovakia, during the years 1984 to 1987. Virus AV 172 has been found to represent probably a new species (designated virus "Sedlec") of family Bunyaviridae. Sedlec virus is pathogenic to suckling and adult mice when inoculated intracerebrally (i.c.) but not intraperitoneally (i.p.) and its ether-sensitive spherical particles measures 90-100 nm.
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Prevalence of borreliae in Ixodes ricinus ticks from southern Moravia, Czechoslovakia.
A total of 378 adult Ixodes ricinus ticks were collected by flagging vegetation in four localities of two districts (Breclav, Znojmo) in south Moravia and examined microscopically. Borreliae were identified in Giemsa-stained midgut smears from 32 (i.e. 8.5%) ticks (9.4% females, 7.2% males); the infection rate varied between 0.0 and 11.4% in the four localities examined. Among female ticks, significantly more were found to be infected in autumn (19.7%) than in spring (5.8%). Dark-field (DF) and Giemsa-stained smears (GS) examinations were compared for their sensitivity in detecting borreliae in 128 field-collected ticks; GS method showed a little higher sensitivity (11.7% ticks were positive) than DF procedure (9.4% ticks positive). Two strains of Borrelia burgdorferi were isolated from a total of 150 adult I. ricinus ticks cultured in BSK medium.
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[The identification of Borrelia isolated in the Soviet Union and Czechoslovakia from Ixodes ricinus (L.) ticks].
Seven strains of the causative agent of Lyme borreliosis have been isolated from ticks of the species Ixodes ricinus (L.) obtained at the territories of Leningrad Province, Lithuania and Czechoslovakia. The strains have been studied in reactions with 5 types of monoclonal antibodies. All isolated strains belong to serotype II according to Barbour's system and are typical for European strains.
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Francisella tularensis from ixodid ticks in Czechoslovakia.
A total of 26,478 ixodid ticks (935 pools) were examined by intracerebral inoculation of suckling mice. Six species of ticks were tested: Ixodes ricinus (23,470 individuals), I. trianguliceps (12), Haemaphysalis punctata (831), H. concinna (39), Dermacentor reticulatus (69) and D. marginatus (2,057). The ticks were collected largely by flagging vegetation, a substantial minority (4%) from animals. Three strains of Francisella tularensis were isolated, one each from I. ricinus (males, district Breclav, southern Moravia), D. reticulatus (males, district Breclav) and D. marginatus (engorged females collected from sheep in Roznava district, eastern Slovakia). D. marginatus and D. reticulatus represent new vector species for Czechoslovakia.
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[An arbovirus study of pregnant women in Southern Moravia].
The authors revealed by means of the haemagglutination-inhibition test (HIT) and the plaque reduction neutralization test (PRNT) that in 1983 to 1985 pregnant women in the Breclav district became infected with the Tahyna virus. HI antibodies against the virus were detected in 96 (28.4%) women from a total of 338 examined. A new infection was proved in 15 (4.4%) women. The majority of infections was contracted in August to October. Positive results were supported by the PRNT. Antibodies against arboviruses Sindbis, Calovo, West Nile, tick-borne encephalitis, Bhandza were not detected in any of the women.
Adolescent↗
Results of arbovirological examination of birds of the family Hirundinidae in Czechoslovakia.
Migratory birds (swallow, Hirundo rustica; sand martin, Riparia riparia; house martin, Delichon urbica) caught in southern Moravia (Czechoslovakia) in 1984-87 were examined for arbovirus infections. Isolation experiments were carried out using blood samples of 183 birds (52 swallows, 107 sand martins, and 24 house martins). The results were negative. Serological examinations of 136 birds (36 swallows, 86 sand martins, and 14 house martins) were made by haemagglutination-inhibition test (HIT) using 6 arboviral antigens of the genera Alphavirus (Sindbis--SIN) and Flavivirus (tick-borne encephalitis--TBE, West Nile--WN) and of the family Bunyaviridae (Tahyna--TAH, Calovo, CVO, and Bhanja--BHA). Antibodies against all of the tested viruses were detected at different rates: SIN 2.9%, TBE 1.5%, WN 1.5%, TAH 4.4%, CVO 1.5%, and BHA 2.2%. The titres ranged from 1.20 to 1.80.
Alphavirus↗
Isolation of "exotic" Bhanja virus (Bunyaviridae) from ticks in the temperate zone.
One strain of Bhanja virus was isolated from Dermacentor marginatus male ticks collected from sheep in Slovak Karst, eastern Czechoslovakia (48 degrees 31'N, 20 degrees 28'E). In addition, three strains of Brezová virus (subtype of Tribec orbivirus, Reoviridae) were isolated from Ixodes ricinus ticks. The result represents the northernmost isolation of Bhanja virus and, moreover, its first recovery from D. marginatus in Europe. Cross-neutralization plaque reduction test revealed antigenic similarity of the Czechoslovak strain to the south-European isolates of Bhanja virus, but a more distant relationship to virus strains isolated in Africa and Asia.
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Thermal sensitivity of Clostridium botulinum type C toxin.
A sterile suspension containing 950 mouse LD50 per ml of type C botulinum toxin was exposed for various periods to different temperatures. The time required for the 99% (hundred-fold) reduction of toxicity was more than 5 years at -70 degrees C or -20 degrees C, 6 months at +5 degrees C, 3 weeks at +20 degrees C, 2 weeks at +28 degrees C, 2 days at +37 degrees C, 9 h at +42 degrees C, less than 30 min at +56 degrees C, less than 20 min at +60 degrees C, and below 5 min at +80 degrees C. The results suggest that Clostridium botulinum type C toxin, if produced in an ecosystem of the mild climatic zone, might persist there over the winter season and cause the intoxication of vertebrates next early spring in the absence of further microbial toxigenesis.
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[Comparison of 3 serological tests for the detection of antibodies to Bhanja virus in domestic ruminants].
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Animals↗