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Biomedical subjects

Z Hubálek

Publications and source records attributed to Z Hubálek.

At least 19 recordsLinked to original sources
PubMed2006

Effect of forest clearing on the abundance of Ixodes ricinus ticks and the prevalence of Borrelia burgdorferi s.l.

Questing Ixodes ricinus L. (Acari: Ixodidae) ticks were collected on a forest trail that had been completely cleared of shrubs and ground vegetation in winter 2002 and on a nearby control uncleared forest transect in South Moravia (Czech Republic). Samples were collected each May in 2003, 2004 and 2005. Nymphal ticks were 3.4 times, 1.9 times and 1.2 times less frequent on cleared forest than on uncleared forest trails in the three respective years, whereas adult tick abundance was 27.2 times, 4.0 times and 2.2 times lower, respectively. The ticks were examined for borreliae by dark-field microscopy: prevalence of nymphal ticks infected with Borrelia burgdorferi sensu lato (12.6% to 20.0%) did not differ significantly between the cleared and uncleared trail during the 3 years. In conclusion, the habitat modification appeared to result in a decreased abundance of I. ricinus as well as a reduced frequency of infected ticks (and thus indirectly a lower potential risk of Lyme borreliosis), which lasted, however, for only 2 years. Eight cultures of borreliae isolated from the ticks were all identified as the 'ornithophilic' genomic species Borrelia garinii, possibly indicating a greater role of forest birds than that of forest rodents as the hosts of immature I. ricinus in the tick (and borrelial) colonization of the cleared part of the forest.

Animals↗
PubMed2005

Emmonsiosis of subterranean rodents (Bathyergidae, Spalacidae) in Africa and Israel.

The presence of adiaspores of the fungal genus Emmonsia was examined in the lungs of 85 mole rats representing 3 subterranean genera: blind mole rats (Spalax galili and S. golani) from Israel, Ansell's mole-rats (Cryptomys anselli) from Zambia, and silvery mole-rats (Heliophobius argenteocinereus) from Malawi and Zambia. Emmonsiosis was found in 28% of the blind mole rats, 100% of the Ansell's mole-rats, but in none of the silvery mole-rats. Infection in African mole-rats was caused by Emmonsia parva, and infection in Israeli blind mole rats was caused by E. parva and E. crescens. The study indicates that the perennial burrow system of the Ansell's mole-rat forms an appropriate microhabitat for the saprophytic growth of E. parva in Lusaka region, Zambia. We suggest that factors contributing to the striking difference in prevalence of emmonsiosis between the two African mole-rat genera (Cryptomys, Heliophobius) may be their differing burrow types, burrow longevity, and social lives.

Africa↗
PubMed2004

Borreliae in Ixodes ricinus ticks feeding on humans.

A total of 298 Ixodes ricinus (L.) ticks (Acari: Ixodidae) feeding on humans in the Czech Republic were tested for borreliae (Borrelia burgdorferi sensu lato) by darkfield microscopy between 1997 and 2003. A majority (68%) of the supplied I. ricinus ticks were nymphs, 25% were females and 7% were larvae. Overall, 20% of 74 examined females and 9% of 203 examined nymphs (but none of 21 examined larvae) were infected with borreliae. The proportion of ticks with a high infection load (>100 spirochetes) was 4% in females and 2% in nymphal I. ricinus. During the year, the highest numbers and proportions of infected nymphal and female ticks were taken from humans in June. Detection of borreliae in the ticks feeding on humans might be helpful in the prophylaxis of Lyme borreliosis.

Animals↗
PubMed2004

[Antibodies against mosquito-born viruses in human population of an area of Central Bohemia affected by the flood of 2002].

In the Central-Bohemian area affected by the flood of 2002, 497 residents were screened for antibodies against the mosquito-borne viruses Tahyna (TAHV), West Nile (WNV), Sindbis (SINV) and Batai (BATV; syn. Calovo) using the haemagglutination-inhibition (HIT) and plaque-reduction neutralization (PRNT) tests. Blood samples were collected in September 2002 when the mosquito populations showed the maximum density following the flood. Antibodies against TAHV (16.5% persons in PRNT, 14.9% in HIT), SINV (1.4% in HIT) and BATV (1.4% in HIT, 0.2% in PRNT) were detected. Although 6.8% and 1.2% of the subjects tested reactive with WNV in HIT and PRNT, respectively, the results were interpreted as cross-reactivity with tick-borne encephalitis virus. The seroprevalence of TAHV (both in PRNT and HIT) showed no association with gender (15.8% of males, 16.9% of females), increased with age (1.4% of persons younger than 20 years, 11.2% of persons aged between 20 and 50 years, and 26.2% of persons older than 50 years were positive), and correlated with the mosquito peri-residential challenge (5.0% residents seropositive in a mosquito-free control zone D--mostly Prague, 14.7% in a mild-risk zone C, 20.5% in a moderate-risk zone B, and 28.0% in the most heavily mosquito-infested risk zone A). The highest TAHV seropositivity rate (> 25%) was found amongst the inhabitants of the villages Obríství, Kozly, Tuhan, Chrást, Chlumín and Hostín. Paired blood samples were obtained from 150 of the persons at a 6-month interval: an infection episode with TAHV during or after the flood was clearly evidenced in one person living in Obríství, and less convincing findings of recent TAHV infections were found in other three residents of Chlumín and Obríství (seroconversion and/or significant antibody titres increase detected in HIT only). This serosurvey indicated the existence of an active natural focus of Valtice fever (TAHV infection) stretched along the river Labe nearby Neratovice (Obríství, Chlumín, Tuhan; Kozly, Tisice, Chrást), and a low TAHV activity area along the lower reaches of the river Vltava between Zloncice and Bukol/Zálezlice. An increased population density of mosquitoes after the flood may have boosted the incidence of mosquito-borne virus diseases, particularly Valtice fever, in Central Bohemia. An optimum prophylactic strategy to control these diseases would be epidemiological surveillance (including monitoring of both the density of mosquitoes and their rate of infection with viruses in natural foci) on the basis of which antiepidemic measures such as integrated mosquito control can be taken.

Animals↗
PubMed2003

Screening for West Nile virus infections of susceptible animal species in Austria.

Avian mortality and encephalomyelitis in equines are considered good indicators for West Nile virus (WNV) activity. We retrospectively tested 385 horse sera for WNV antibodies and looked for WNV nucleic acid and/or WNV antigen in paraffin embedded tissues from 12 horses with aetiologically unresolved encephalomyelitis and 102 free-living birds of different species which had been found dead. With the exception of four horses originating from eastern European countries investigated on the occasion of transit through Austria, all horse sera were negative. Nested RT-PCR of the horse tissues yielded no amplification of WNV-RNA. Also, all bird samples, examined by immunohistochemistry, in situ hybridization and nested RT-PCR were negative for WNV. These results indicate that currently WNV cannot be considered a significant pathogen in Austria.

Animals↗
PubMed2003

Migratory birds and West Nile virus.

West Nile virus was first recorded in the New World during August 1999 in New York City. Aetiology of the disease in the Old World indicated birds as the likely introductory and amplifying hosts with ornithophilous mosquitoes, e.g. Culex pipiens, as the principal vectors. Speculation regarding likely agents for movement of the virus in its new environment focused on migratory birds, but evidence to date is equivocal. While spread of the disease has been fairly rapid, at a rate of roughly 70 km a month, it has not shown the kind of long-distance, leap frog movements one might expect if transient birds were the principal introductory hosts. Furthermore, movement of the disease has not been focused southward, but shows a radiating pattern with detection sites located in all directions from New York where terrestrial habitat was available. In addition, tests among potential New World, avian hosts have revealed prolonged viraemia (up to 5 days) only in the relatively non-migratory House Sparrow (Passer domesticus). Dispersal movements by this species could account for the observed pattern of West Nile virus spread in the Western Hemisphere to date. Regardless of whether avian migration, dispersal, or some other agent is responsible, West Nile virus should reach the New World tropics in another 1-2 years, at which time a vast number of new potential introductory and amplifying avian hosts would be exposed to the disease and mosquito vectors would be available throughout most of the year, likely causing serious, long-term threats to human health and vulnerable avian populations in the region.

Animals↗
PubMed2003

Longitudinal surveillance of the tick Ixodes ricinus for borreliae.

Host-seeking Ixodes ricinus (L.) (Acari: Ixodidae) were monitored for borreliae (Borrelia burgdorferi s.l.) using dark-field microscopy in South Moravia (Czech Republic) each May from 1991 to 2001 (150 nymphs, 100 females and 100 males each year). This survey revealed a mean annual percentage of infected ticks of 16.8% (range, 11.7-24.2) in nymphs, 24.9% (range, 16.5-33.6) in females and 26.1% (range, 17.1-37.3) in males. Annual incidence of Lyme borreliosis in humans of the area in the same period (range, 8.7-41.7 per 100,000) correlated significantly with the frequency (number of ticks per flag per hour) of nymphs infected with >50 borreliae or all nymphal ticks, but not with the frequency of females, infected females or the infection rate (% of ticks infected) of either nymphal or female ticks. A prediction of the annual incidence of Lyme borreliosis, based on the frequency of heavily infected or all nymphal I. ricinus ticks, is feasible. The infection rate in I. ricinus correlated significantly with the North Atlantic Oscillation winter index of the last year (in nymphs) or of the year before last (in adults).

Aging↗
PubMed2003

[Borrelia in ticks biting humans and prevention of Lyme borreliosis].

We examined by dark field microscopy 195 of 209 Ixodes ricinus ticks that were removed from humans in the Czech Republic (mainly in southern Moravia) during 1997-2001. The majority of the ticks were nymphs (62%), 31% were females and 7% larvae; 10.7% of the nymphs, 20.3% of the females but no larvae were found to be infected with B. burgdorferi s.l., the agent of Lyme borreliosis (LB). This observation supports for Central Europe the conclusions drawn from North America about nymphal ixodid ticks as the most important vector stage in transmission of LB. In the course of the year, we found the highest proportion of infected nymphal and female ticks taken off humans in June. The detection of borreliae in a human-biting tick is an important step that enables the general practitioner to prescribe prophylactic antimicrobial treatment and to reduce significantly the risk of Lyme disease in the patient.

Animals↗
PubMed2003

[A case of Babesia microti imported into the Czech Republic from the USA].

Human babesiosis is a zoonotic tick-borne protozoan infection caused by several species of the genus Babesia. It is a rare disease in Europe. Until recently, 31 cases have been described. Most of them were severe infections caused by a cattle parasite Babesia divergens in splenectomized patients. In contrast, a rodent species Babesia microti was responsible for hundreds of cases of human babesiosis in the U.S.A. In this report we describe the first case of human babesiosis in the Czech Republic. To our knowledge, it is also the first case of symptomatic B. microti infection imported to Europe from the United States.

Babesia microti↗
PubMed2001

Enzyme activities of Borrelia burgdorferi sensu lato.

Activities of 19 enzymes were tested by the API ZYM system in 13 strains of Borrelia burgdorferi sensu lato (B. burgdorferi sensu stricto, B. afzelii, B. garinii, B. lusitaniae, B. valaisiana) grown in liquid BSK-H medium supplemented with rabbit serum. All strains produced acid phosphatase, esterase (C4), esterase-lipase (C8), leucine arylamidase and naphthol-AS-BI-phosphohydrolase. Nine strains also produced alkaline phosphatase, and three strains produced alpha-glucosidase. The API ZYM system probably cannot be used for differentiation between B. burgdorferi sensu lato genomospecies.

Acid Phosphatase↗
PubMed2001

[Analysis of the incidence of tularemia in the Breclav District 1994-1999].

Southern Moravia is one of the areas where there are long-term natural foci of tularaemia. In 1994 in the Breclav district an exacerbation of the disease was recorded in hares. During autumn hunts a positive reaction was recorded in 5.75% of examined hares. An elevated seropositivity persisted also in subsequent years and at the same time a higher human morbidity in the mentioned region. The objective of the investigation was to assess the causes and circumstances which led to the exacerbation of old known but in recent years quiescent foci in the mentioned region. To this end 350 small terrestrial mammals were examined. In one case it proved possible to detect the causal agent in Microtus arvalis. By examination of arthropods it proved possible to isolate 33 strains, i.e. 32 strains from ticks Dermacentor reticulatus and one strain from Ixodes ricinus. The results of the examination revealed that tularaemia as a classical infection with a natural focus may persist in areas where there are prerequisites for survival of the causal agent in the environment. One of the important factors of the environment are susceptible individuals (hares, small terrestrial mammals) as well as blood sucking arthropods as vectors of the disease.

Animals↗
PubMed2000

European experience with the West Nile virus ecology and epidemiology: could it be relevant for the New World?

A review of West Nile virus (WNV) and the epidemiology of West Nile fever (WNF) in Europe is presented. European epidemics of WNF reveal some general features. They usually burst out with full strength in the first year, but few cases are observed in the consecutive 1 to 2 (exceptionally 3) years, whereas smaller epidemics or clusters of cases only last for one season. The outbreaks are associated with high populations of mosquitoes (especially Culex spp.) caused by flooding and subsequent dry and warm weather, or formation of suitable larval breeding habitats. Urban WNF outbreaks associated with Culex pipiens biotype molestus are dangerous. Natural (exoanthropic, sylvatic) foci of WNV characterized by the wild bird-ornithophilic mosquito cycle probably occur in many wetlands of climatically warm and some temperate parts of Europe; these foci remain silent but could activate under circumstances supporting an enhanced virus circulation due to appropriate abiotic (weather) and biotic (increased populations of vector mosquitoes and susceptible avian hosts) factors. It is very probable that WNV strains are transported between sub-Saharan Africa and Europe by migratory birds. The surveillance system for WNF should consist of four main components: (1) monitoring of mosquito populations and their infection rate; (2) wild vertebrate surveys; (3) sentinel birds (domestic ducks rather than chickens); and (4) monitoring of human disease. In the case of persisting high risk of WNF for humans and equids in certain enzootic areas, immunization against WNF should be considered. For that purpose a commercially available, cross-protective vaccine against Japanese encephalitis could be used.

Animals↗
PubMed2000

West Nile virus investigations in South Moravia, Czechland.

Seven virus isolates were obtained from 11,334 mosquitoes after the 1997 Morava River flooding in South Moravia (Czech Republic): 6 strains of Tahyna bunyavirus, California antigenic group (5 from Aedes vexans, 1 from Ae. cinereus), and 1 strain of West Nile flavivirus (WNV) from Culex pipiens. In 1999, one isolate of Tahyna virus from Ae. vexans and one isolate of WNV from Cx. pipiens were recovered from a total of 14,354 mosquitoes examined in the same area, whereas no virus was detected there in 1,179 overwintering mosquitoes (mostly Cx. pipiens) in March 2000. The infection rate of mosquitoes with arboviruses was significantly higher in 1997, the year of the flood and an enormously high population density of mosquitoes. Antibodies neutralizing WNV were detected in 13 of 619 (2.1%) hospitalized patients or persons seeking outpatient clinics of the area in 1997. Five of the seroreactors revealed clinical symptoms compatible with West Nile fever: in 2 of them (children), recent infection with WNV was confirmed by a significant increase of antibody titer between acute and convalescent serum samples.

Adolescent↗
PubMed1999

Isolation of Borrelia afzelii from overwintering Culex pipiens biotype molestus mosquitoes.

During the years 1995-1996, a total of 1,743 overwintering Culex pipiens biotype molestus female mosquitoes were tested for the presence of spirochetes in several localities in South Moravia, Czech Republic.The spirochetes were observed in 5% of the mosquitoes investigated. One of the five isolated strains of spirochetes (BR-84) was identified as Borrelia afzelii. The potential role of mosquitoes in the ecology and epidemiology of Lyme disease (LD) borreliae should be further investigated.

Animals↗
PubMed1999

Emmonsiosis of wild rodents and insectivores in Czechland.

Adiaspores of the fungus Emmonsia crescens were detected microscopically in the lung tissue of 13% of 10.081 small mammals belonging to 24 species examined in 14 areas of the Czech Republic between 1986 and 1997; 441/1.934 (23%) Clethrionomys glareolus, 1/6 (17%) Arvicola terrestris, 357/2.172 (16%) Apodemus flavicollis, 220/1.981 (11%). A sylvaticus, 23/265 (9%) A. microps, 11/81 (14%) Microtus subterraneus, 93/1.275 (7%) M. arvalis, 98/1.439 (7%) M. agrestis, 1/3 (33%) Ondatra zibethicus, 1/1 Cricetus cricetus, 1/20 (5%) Crocidura suaveolens, 2/40 (5%) Neomys fodiens, and 13/529 (2%) Sorex araneus were infected. Emmonsiosis was not recorded among the species of rodents that do not build their nests in the soil (Muscardinus avellanarius, Micromys minutus, Mus musculus, Rattus norvegicus). The overall prevalence of emmonsiosis was significantly higher in adult (19%) than in juvenile (7%) mammals, and in rodents (13%, and 20% in adults) than in insectivores (2%, and 4% in adults). The frequency of infected mammals also varied according to geographic area, altitude, habitat, and season.

Age Distribution↗