Temporal risk assessment for Lyme borreliosis in Denmark.

The prevalence of Borrelia burgdorferi sensu lato in Ixodes ricinus nymphs in Denmark was found to be approximately 5%. The mean abundance of infected nymphs varied from 0.3 to 4.4 per 100 m2 according to site. The seasonal occurrence of infected nymphs in a beech forest coincided with seasonal distribution of neuroborreliosis cases. In order to establish a working hypothesis, it was assumed that the availability of habitats and human habitat preferences is one of the factors leading to low number of neuroborreliosis cases in the spring. In addition, this paper gives a description of the neuroborreliosis cases in Denmark in the period 1985-97 and offers a possible explanation for the variation in cases. The explanation is based on an assessment of tick density, which by comparison with the number of neuroborreliosis cases provides information on the infectivity of ticks. The model suggests that high temperatures and low precipitation in the autumn is essential for the transmission of B. burgdorferi sensu lato to reservoir hosts or development of B. burgdorferi sensu lato within ticks, which secures high tick infectivity in the following season.

Spatial risk assessment for Lyme borreliosis in Denmark.

A study of nymphal and adult Ixodes ricinus density was performed in well-defined spruce and beech forest habitats with different levels of roe deer abundance and soil water capacity. In 35 habitats, a total of 489 larvae, 1,611 nymphs and 193 adult I. ricinus ticks were collected. Tick density was found to be influenced by roe deer abundance and soil water capacity. Based on this evaluation, a model predicting increasing number of ticks with increasing roe deer abundance and soil water capacity was suggested. A total of 1,045 nymphs and 106 adult ticks were tested for infection with Borrelia burgdorferi sensu lato Of these, 53 nymphs and 6 adults were found to be infected, leading to an general infection rate of 5% and 6% for nymphs and adults, respectively. Prevalences of Borrelia burgdorferi sensu lato in nymphal I. ricinus were found to be independent of roe deer abundance and soil water capacity. The correlation between human neuroborreliosis incidence and the estimated number of I. ricinus based on roe deer abundance and soil water capacity was examined. Differences in human neuroborreliosis incidence were found to correspond with the expected spatial differences in tick density in 12 counties in Denmark.

Differentiation of cuticular structures during the growth of the third-stage larva of Ascaris suum (Nematoda, Ascaridoidea) after emerging from the egg.

In order to monitor the early phases of the development of Ascaris suum from domestic pigs, third-stage larvae, retrieved from the liver and the lungs, were studied by analyzing worm growth and length increase of individual transverse annuli in the cuticle. Material for study using light and scanning electron microscopy was obtained from experimental infections. The results show that the third-stage larva (not the second-stage) after emergence from the egg grows continuously, without an ecdysis in the liver. During growth, each annulus is split into a complex of 2 subannuli, each of which attains a bimodal appearance and is a prominent feature during a late phase of the third-stage larva. The results suggest that the first 2 molts occur inside the egg, a synapomorphic feature of the Ascaridoidea. The third-stage larvae of ascaridoids, with some functional similarities of the dauer-larva stage of Caenorhabditis sp., facilitate transmission of these parasitic worms to the digestive tract of the vertebrate final host (utilizing the tracheal route in A. suum), where the third and the fourth molts take place.

Prevalence of gastrointestinal helminths in different poultry production systems.

A cross-sectional prevalence study of gastrointestinal helminths in Danish poultry production systems was conducted on 268 adult chickens selected at random from 16 farms in Denmark from October 1994 to October 1995. The trachea and the gastrointestinal tract of each bird was examined for the presence of helminths. In the free-range/organic systems the following helminths were found: Ascaridia galli (63.8%), Heterakis gallinarum (72.5%), Capillaria obsignata (53.6%), Capillaria anatis (31.9%) and Capillaria caudinflata (1.5%). In the deep-litter systems: A. galli (41.9%), H. gallinarum (19.4%) and C. obsignata (51.6%). In the battery cages: A. galli (5%) and Raillietina cesticillus or Choanotaenia infundibulum (3.3%). Exact identification of the cestodes was not possible because of missing scolexices. In the broiler/parent system: C. obsignata (1.6%), and finally for the backyard system: A. galli (37.5%) H. gallinarum (68.8%), C. obsignata (50.0%), C. anatis (56.3%) and C. caudinflata (6.3%). The results confirm the higher risk of helminth infections in free-range and backyard systems but prevalence may also be high in deep litter systems.

Centrids, a pair of asymmetrically arranged sense organs in Ascaris suum (Nematoda, Ascaridoidea).

Two prominent, asymmetrically placed cuticular somatic sensilla, called centrids, are reported in Ascaris suum Goeze, 1782, the pig roundworm. The right centrid is situated much more anteriorly on the body than is the left one. The centrids are globular in the fourth-stage larva and obviously void of an apical pore, suggesting at least a tactile function. In adult worms, the centrids are platelike, lacking a globular expansion. The observation on the presence of asymmetrically placed centrids in A. suum gives further impetus to the importance assigned to sense organs in the classification and identification of nematodes. The name centrid was originally chosen to indicate the placement of the papillae in the midbody region of worms. The name centrid, rather than, e.g. postdeirid, is proposed to be used when denoting asymmetrically oriented midbody sensilla among the Ascaridida and papillae, when shown homologous to these, of species within the Rhabditea generally. This proposal is in line with the name "Mittelkörperpapillen" originally adopted to denote homologous sensillae in Cucullanidae (Seuratoidea) by Törnquist in 1931.

Ascaridia galli infections in free-range layers fed on diets with different protein contents.

1. One hundred and twenty 17-week-old Lohman Brown hens were divided into 4 groups. Groups 1 and 3 were given a diet with 180 g protein/kg and groups 2 and 4 were given a diet with 140 g protein/kg. Groups 1 and 2 were orally infected with 500 (+/- 50) embryonated Ascaridia galli eggs. 2. Marked differences in mean weekly weight gain for the 4 groups were observed. 3. Hens given 140 g protein/kg had a significant lower mean worm burden of adult A. galli worms and a significant lower weight gain compared to the group given 18 g protein/kg. 4. There was no significant difference in faecal egg counts between the 2 parasitised groups. 5. The egg production did not differ significantly between any of the groups. 6. The results of this study indicate that the amount of dietary protein in the diet has an effect on the establishment of A. galli infections in the gut of layers kept under free range conditions.

Ixodes ricinus strains in Europe.

An analysis of cuticular hydrocarbons (CH) of unfed adult Ixodes ricinus ticks collected throughout Europe showed that there are 10 distinct I. ricinus groups. Studies on the seasonal and annual consistency of CH composition and possible effects of host and environmental factors suggested that CHs may be used as a genuine genetic marker for I. ricinus. Preliminary studies compared the vector competence of ticks from three of the most separated I. ricinus groups and the results suggested that there may be significant differences in tick susceptibility to Borrelia afzelii.

European reservoir hosts of Borrelia burgdorferi sensu lato.

Existing knowledge on reservoir hosts of Borrelia burgdorferi sensu lato was collated and reviewed and several species, particularly birds, were identified as reservoir competent. At the present time, 9 small mammals, 7 medium-sized mammals and 16 bird species, including passerines, sea birds and pheasants, appear to be capable of transmitting spirochaetes to ticks and thus of participating in the natural circulation of B. burgdorferi s.l. in Europe. The house mouse, Mus musculus is strongly suspected of reservoir competence and many other small rodent species, particularly in eastern Europe and Russia, have been implicated. Ungulates are not thought to play a major role as reservoir hosts, though co-feeding transmission may permit some tick infection. The criteria for establishment of reservoir status are outlined and a method for identification of host blood meals of previous instars of unfed ticks, developed in a participant laboratory, is briefly described.

Growth and structural features of the adult stage of Ascaris suum (Nematoda, Ascaridoidea) from experimentally infected domestic pigs.

For studying the morphogenesis of the adult stage of Ascaris suum, worms were obtained from experimentally infected domestic pigs. Structural and morphometric features of A. suum are analyzed by light and scanning electron microscopy. It was shown that the increase in length of the worm from days 35 to 56 is based on a region-specific lengthening of individual transverse annuli in the cuticle. An increased worm size also results in an increased diameter of different cuticular sense organs. It is shown that a pair of lateral midbody papillae, the centrids, are prominent sensilla in the adult male and female worm. The centrids have an asymmetric placement, the right centrid being more anterior on the worm than the left.

Studies on Ascaridia galli in chickens kept at different stocking rates.

The development of Ascaridia galli infections was investigated over a period of 378 days in parasite naive chicken flocks ('permanent flocks') kept at different stocking rates and infected by introducing previously infected chickens (seeder birds). The results of this study indicated that differences in stocking rate may lead to different levels of establishment of A. galli infections in chickens. Furthermore, significantly higher weight gains were seen in the medium stocking rate (MSR) group than in either the low stocking rate (LSR) or the high stocking rate (HSR) groups. Periodically, the egg excretion was significantly different between the groups. Although not significant for the whole period, the general trend was that the egg excretion was lower in the MSR group than the LSR and HSR groups. The mean worm burdens in the permanent flocks at the end of the experiment were not significantly different from each other. To estimate the availability of infective eggs in the houses and pens, tracer animals were introduced into each of the permanent flocks every month. Information derived from tracer animals did not confirm an effect of stocking rate on the availability of infective eggs in the environment, although there was a trend towards higher mean worm burdens in the tracers from the MSR group.

A cross-sectional study of helminths in rural scavenging poultry in Tanzania in relation to season and climate.

A cross-sectional study on the prevalence of helminths in rural scavenging poultry on six hundred adult chickens selected randomly from six villages in the Morogoro Region, Tanzania during the wet and the dry seasons, was conducted. The trachea and gastrointestinal tract of each bird were examined for the presence of parasites. All chickens were infected with one or several species of helminths, the average being 4.8 +/- 1.7 helminths per chicken during the wet season and 5.1 +/- 1.8 during the dry season. A total of 29 different helminth species were shown in the trachea or the gastrointestinal tract. The following species were identified: Syngamus trachea (0.7% (wet season), 2% (dry season)); Gongylonema ingluvicola (6.3%, 17.7%); Tetrameres americana (54.3%, 60.3%); Dispharynx nasuta (0%, 2.7%); Acuaria hamulosa (8.3%, 19.3%); Ascaridia galli (28.3%, 32.3%); Heterakis gallinarum (74.0%, 78.7%); H. isolonche (18.7%, 5.0%); H. dispar (25.7%, 6.3%); Allodapa suctoria (40.0%, 52.0%); Subulura strongylina (3.3%, 1.0%); Strongyloides avium (0.3%, 3.0%); Capillaria annulata (2.0%, 0.0%); C. contorta (9.0%, 1.0%); C. caudinflata (2.0%, 4.3%); C. obsignata (8.7%, 25.0%); C. anatis (4.0%, 9.0%); C. bursata (1.0%, 2.7%); Raillietina echinobothrida (41.3%, 46.3%); R. tetragona (25.3%, 21. 3%); R. cesticillus (8.7%, 2.7%); Choanotaenia infundibulum (0.0%, 3. 7%); Hymenolepis carioca (9.0%, 18.0%); H. cantaniana (48.0%, 43. 0%); Amoebotaenia cuneata (39.3%, 36.0%); Metroliasthes lucida (1.0%, 0.3%); Davainea proglottina (5.7%, 0.3%) and Polymorphus boschadis (0.3%, 0.0%). No trematodes were found. No correlation was found between season and prevalence, or season and mean worm burdens. Twelve helminths of the species recovered represent new local records.

Ascaridia galli populations in chickens following single infections with different dose levels.

In all, 3 groups of 20 Lohman Brown chickens aged 1 day were orally infected with doses of 100, 500, or 2,500 embryonated Ascaridia galli eggs, respectively. After 8 weeks, egg counts (eggs per gram of feces, EPG) were determined for all animals prior to slaughter. The gastrointestinal tracts were examined for the presence of adult and immature stages of A. galli. All groups had roughly similar worm burdens and, hence, significantly different establishment rates of 14.2%, 2.9%, and 0.5%, respectively. A significantly lower mean female worm burden was seen in the high-dose group (P = 0.02), which also showed a significantly lower level of egg excretion (P = 0.01). However, fecundity (EPG per female) did not significantly differ between the groups (P = 0.55). The mean lengths of adult worms as well as the weight of the mean worm burdens were significantly smaller in the high-dose group. This study demonstrated that single infections with varying doses of A. galli eggs influenced the establishment rate, sex ratio, egg excretion, and worm size and weight but not the worm fecundity.

Ultrastructure and development of the body cuticle of Oesophagostomum dentatum (Strongylida, Nematoda).

The ultrastructure, development, and morphogenesis of the body cuticle of adult and juvenile Oesophagostomum dentatum (Strongylida, Nematoda) were investigated by light microscopy, scanning electron microscopy, and transmission electron microscopy. The cuticle of the first 3 juvenile stages consists of a trilaminate epicuticle, an amorphous layer, and a radially striated layer. In the last juvenile stage and the adult worm, the radially striated layer is replaced by a fibrous layer with 3 sublayers of giant fibers and a basal amorphous layer. The new forming cuticle of the 3rd juvenile stage exhibits the epicuticle and amorphous material and, at a later time, the epicuticle and the radially striated layer; finally, amorphous material appears between these layers. Our finding of a structural change in the cuticular morphology between the 3rd and 4th juvenile stage harmonizes with earlier reports about the Strongylida. Such a change occurs at different ontogenetic stages or seems to be missing in other nematodes. Morphogenetic events such as the formation of the radial striation layer from amorphous precursor material agrees with previous observations on strongylids.

Prevalence of antibodies to Borrelia burgdorferi in Danish rodents.

Six rodent species from six Danish localities were examined for antibodies to Borrelia burgdorferi by immunofluorescence assay (IFA). A total of 1097 specimens were tested using a serum titre of 1:8. The wild mice Apodemus sylvaticus and A. flavicollis had high prevalences of B. burgdorferi antibodies of 42.1% and 27.9% respectively, but the vole Microtus agrestis also showed an exceptionally high prevalence of 32.7%. Clethrionomys glareolus had a low average prevalence of 17.4%. The lowest and highest prevalences of rodents seropositive for B. burgdorferi of 6.5% and 100% were found for Micromys minutus and Mus musculus respectively. Twice as many of the Microtidae voles (M. agrestis and C. glareolus) as of the family Muridae were caught, and in Denmark the actual number of seropositive Microtidae was 1.6 times higher than for Muridae. The results indicate that in Denmark the family Microtidae species plays an important role as an animal reservoir host for B. burgdorferi. The prevalence of antibodies against B. burgdorferi varied from locality to locality, but seropositive rodents were found at all localities examined, indicating that the spirochete was widely present in Denmark.

Entomopathogenic fungi associated with Ixodes ricinus ticks.

The objective of this study was to demonstrate the occurrence of entomopathogenic fungi on Ixodes ricinus ticks in relation to the tick stage, engorgement and season. Ticks were collected from the vegetation, from small rodents and from deer. All entomopathogenic fungi found belonged to the Hyphomycetes. Paecilomyces farinosus and Verticillium lecanii were the predominant species. Other species, found only on engorged females were: Beauveria bassiana, B. brongniartii, P. fumosoroseus and V. aranearum. Eight out of 1833 ticks collected from the vegetation and three out of 269 engorged nymphs were infected with fungi. Thirty-three out of 149 engorged females were infected, whereas males and engorged larvae were not infected. Throughout the season, a significantly higher proportion of ticks collected in autumn were infected. Entomopathogenic fungi may have a significant impact on the size of the I. ricinus population, since females were the most frequently infected stage.

Prevalence of antibodies to Borrelia burgdorferi in Danish deer.

To estimate the prevalence of antibodies to Borrelia burgdorferi in the most common species of Danish deer, blood samples were collected from roe deer (Capreolus capreolus), fallow deer (Dama dama), and red deer (Cervus elaphus). A total of 156 blood samples were collected primarily from hunts in three areas of Denmark from November 1990 to December 1991. Presence of deer IgG antibodies to the Borrelia burgdorferi strain DK ECM 1 were shown by an indirect immunofluorescence assay at serum titre 1:64. Antibodies to spirochaetes were detected in 52% of roe deer, 38% of fallow deer, and 27% of red deer. There were significant differences between the number of seropositive animals in the three areas of Denmark examined, but no differences could be shown for age, sex or season. The high antibody prevalence indicates that deer are exposed to tick-borne Borrelia burgdorferi throughout Denmark.

The common frog (Rana temporaria) as a potential paratenic and intermediate host for Angiostrongylus vasorum.

Common frogs (Rana temporaria) were exposed either to third-stage larvae (L3) or to first-stage larvae (L1) of Angiostrongylus vasorum. Following exposure to L3, viable larvae could be detected in the frogs for at least 2 weeks. Following exposure to L1, the frogs developed viable L3 in their tissues within 30 days. In a test of the infectivity of these larvae, one fox was fed frogs previously infected with L3 and another fox was fed frogs previously infected with L1. On autopsy it was found that adult A. vasorum populations had been established in both foxes. Thus, it could be concluded that frogs can act not only as paratenic hosts but also as intermediate hosts for A. vasorum.

[Asymptomatic benign mediastinal teratoma]. / Asymptomatisk benignt mediastinalt teratom.

A case of asymptomatic benign mediastinal teratoma is presented. The necessity for definite diagnosis of mediastinal tumours is stressed together with the need for conferences involving several specialties.

[Cost-benefit analysis of electric stimulation of the spinal cord in the treatment of angina pectoris]. / Cost-utility analyse af elektrisk rygmarvsstimulation til behandling af angina pectoris.

Since August 1988, in Odense Hospital, electric spinal cord stimulation (SCS) has been employed for the treatment of pain in patients with confirmed ischaemic heart disease who suffer from incapacitating angina pectoris despite maximal medical/surgical treatment. The object of the present investigation was to assess not only the social economic consequences of SCS treatment (cost-utility analysis) but also altered quality of life in SCS patients (perception of pain, mobility, function in daily life and physical activity). Sixteen consecutive SCS patients all of whom were resident in the County of Funen and who were submitted to implantation of an SCS system during the period August 1988 to December 1989, participated in this investigation. The results are based on data from the year prior to SCS implantation compared with the subsequent time with SCS treatment. Saving was found at hospital level (reduction in number of admissions) og 40,200 Danish crowns/annum/patient (approximately IJ 3,000) (1989 prices), and for non-hospital related expenses a corresponding saving of 16,289 Danish crowns/annum/patient (approximately IJ 1,600) was found mainly on account of reduction in the amount of home nursing required. The total saving was found to constitute 56,489 Danish crowns/annum/patient (approximately IJ 5,600). In addition, improvements were registered in all respects which constituted assessment of the quality of life of the patients.