[Toxocariasis: larva migrans visceralis].
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Biomedical subjects
Publications and source records attributed to P Kimmig.
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Larvae of the trombiculid mite Neotrombicula autumnalis were collected at 18 sites in and around Bonn, Germany, to be screened for infection with Borrelia burgdorferi s.l. by means of PCR. Questing larvae numbering 1380 were derived from the vegetation and 634 feeding ones were removed from 100 trapped micromammals including voles, mice, shrews and hedgehogs. In a laboratory infection experiment, a further 305 host-seeking larvae from the field were transferred onto Borrelia-positive mice and gerbils, and examined for spirochete infection at various intervals after repletion. In three cases borrelial DNA could be amplified from the mites: (1) from a larva feeding on a wild-caught greater white-toothed shrew (Crocidura russula), (2) from a pool of four larvae feeding on a B. garinii-positive laboratory mouse, and (3) from a nymph that had fed on a B. afzelii-positive laboratory gerbil as a larva. In the first case, borrelial species determination by DNA hybridization of the PCR product was only possible with a B. burgdorferi complex-specific probe but not with a species-specific one. In the second case, probing showed the same borrelial genospecies (B. garinii) as the laboratory host had been infected with. In the latter case, however, DNA hybridization demonstrated B. valaisiana while the laboratory host had been infected with B. afzelii. Subsequent DNA sequencing confirmed much higher similarity of the PCR product to B. valaisiana than to B. afzelii indicating an infection of the mite prior to feeding on the laboratory host. The negligible percentage of positive mites found in this study suggests that either the uptake of borrelial cells by feeding trombiculids is an extremely rare event or that ingested spirochetes are rapidly digested. On the other hand, the results imply a possible transstadial and transovarial transmission of borreliae once they are established in their trombiculid host. However, unless the transmission of borreliae to a given host is demonstrated, a final statement on the vector competence of trombiculid mites is not possible.
This study examined the occurrence of Coxiella burnetii (C. burnetii), the infectious agent of Q-fever, in sheep and sheep-ticks in Baden-Wuerttemberg, Germany, as a possible source of infection in Q-fever outbreaks. Using PCR, we examined a total of 1066 Dermacentor ticks from 23 herds and 49 samples of tick excrement from 18 herds for C. burnetii. We found the infectious agent in one non-engorged tick and in one sample of tick excrement from the same herd, in Efringen-Kirchen (district Loerrach). Sequencing the PCR-products confirmed the amplifications as specific for C. burnetii. Further serological tests of random samples of the four districts of Baden-Wuerttemberg showed a seroprevalence from 0 to 1.4% using complement fixation test (CFT), as well as a 0.9 to 10.2% seroprevalence, using ELISA test. Serum samples from a Q-fever-suspicious herd resulted, however, in 6% (CFT) and 53% (ELISA) positive reactions. A comparison between CFT and ELISA showed both a correlation of the two test methods that increased with higher CFT titration levels and positive reactions using ELISA for 9.4% of the serums that had tested negative using CFT. The results of the present study reveal that ticks and their excrements are important vectors of transmission of Q-fever in Baden-Wuerttemberg. Investigations on C. burnetii using PCR as well as serological surveys of sheep are important instruments for diagnosis and disease control of Q-fever.
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BACKGROUND: Out of 2,560 participants in an epidemiological survey of alveolar echinococcosis (AE) performed in 1996 in southwestern Germany, 47 participants had tested seropositive in one of two crude antigen screening ELISAs and were inconspicuous on hepatic ultrasound. PATIENTS AND METHODS: Out of these 47 seroreactors, 36 attended a follow-up examination 30 months after the primary examination, including ultrasound and serology with various Echinococcus multilocularis-specific antigens. RESULTS: No lesion suspicious for AE was detected in any participant. Serology showed only minor changes as compared to the earlier results. CONCLUSION: Persistent seropositivity without detectable hepatic lesions could be interpreted as an early sign of sonographically not yet detectable AE, immunity to E. multilocularis or unspecific serological reactivity. For seropositive and clinically inconspicuous inhabitants of areas endemic for AE follow-up examinations at intervals of 2-3 years seem to be adequate.
The prevalence of different genospecies of Borrelia burgdorferi sensu lato in infected ticks could be a determinant for the risk of acquiring Lyme borreliosis (LB) and its clinical presentation. A total of 7373 ticks and 2761 samples from LB patients from the same area in southwest Germany were analyzed by PCR to assess the frequency of the occurrence of LB-associated genospecies. Fifteen percent of the tick samples and 19% of the human samples were found positive for the presence of B. burgdorferi sensu lato. Further identification of 1106 B. burgdorferi sensu lato positive tick samples by reverse line blotting and 125 positive patient samples by nested PCR using species-specific primers revealed the occurrence of B. afzelii, B. burgdorferi sensu stricto, B. garinii and B. valaisiana. Both single-species and mixed infections were noted and a similar distribution of the different genospecies was found in ticks compared with human samples. It was also the purpose of this study to obtain more information about a possible correlation between the distribution of Borrelia species and clinical syndromes of LB. Skin biopsies of 59 patients with acrodermatitis chronica atrophicans and cerebrospinal fluid samples from 78 patients with possible neuroborreliosis were analyzed. In conclusion, the distribution of the different genospecies in ticks is the decisive factor for the occurrence of the different Borrelia genospecies in samples from LB patients. Borrelia afzelii is the predominant genospecies in all kind of samples from the observed area and there seems to be no association of particular Borrelia genospecies with distinct clinical manifestations of LB.
Hantavirus, originally named after the Hantaan River in Korea, is the aetiologic agent for the Hemorrhagic Fever with Renal Syndrome (HFRS) in the asian region, in the Americas for the Hantavirus Pulmonary Syndrome (HPS). In Middle Europe hantaviruses are responsible for the "Nephropathia Epidemica" (NE), a mild form of HFRS. Hantaviruses belong to the family of Bunyaviridae. Like other members of this family their genome consists of three segments of single stranded RNA (ss-RNA) leading to various subtypes, strongly associated with different rodent hosts. There are two major groups, the hantaan lineage harbored by murine rodents and the Puumala lineage harbored by arvicolidae ("old world") and sigmodontidae ("new world"). Infected rodents may develop chronic infections for months or even life-long and may shed infectious virus with urine and feces. The primary mode of infection of man occurs by inhaling contaminated aerosols or soil particles. The collection of epidemiologic data in the state of Baden-Württemberg was realized in three different steps: Collection and localisation of clinical cases (n = 62): A concentration of clinical cases in the middle of the state was found. The examination of the seroprevalence of exposed persons: By the examination of 4000 sera from forest workers, a seroprevalence with an average of 2.1% was found. In the districts of Reutlingen and Tübingen seroprevalences up to 9% were found. This leads to the assumption that there are endemic areas. Epidemiologic studies of reservoir hosts: Serologic surveys of rodents (n = 1150) in the described areas yielded to a seroprevalence up to 10-30%. Virus carriers were determined with RT-PCR and nested-PCR testing. The prevalence in the rodent population showed an average of 10%. The isolated subtypes were all identified as members of the Puumala-lineage. The origin of sporadic infections with Hantavirus of the Hantaan-lineage in Baden-Wuerttemberg is still unknown.
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Between the turn of the years 98/99 and 99/2000, stool samples from various health departments in the south of Germany were sent to the LGA (Landesgesundheitsamt Baden-Württemberg). Different testings as bacteriological routines for enterobacteriaceae and virological antigen screenings of the stool samples for adeno-, astro- and rotaviruses lead to negative results. Additional RT-PCR tests for the presence of Norwalk-RNA showed nearly 40% of positive samples. From 14 group infections between december 98 and january 2000, 286 samples in total were sent to the LGA, 118 of them gave positive results for the norwalk agent. For the verification of the analysis, some random samples were sent to the Robert-Koch-Institut, div. of molecular virology at Berlin, where the results were confirmed.
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The inhabitants of a rural community in southwestern Germany were examined for alveolar echinococcosis (AE). The study was prompted by the recent increase of the prevalence of the parasite in foxes and the increase of fox populations: in the study area, 75% of the foxes carried Echinococcus multilocularis. The human population was screened using hepatic ultrasound and serology. All participants were interviewed for demographic and potential risk factors. Of 2,560 participants, one was identified with active AE, while 3 others had suspicious liver lesions. Another 9 participants were seropositive for specific antibodies without detectable lesions. Demographic and behavioral factors were not correlated with active or suspected cases nor with seropositivity. If the prevalence of 40/100,000 (95% confidence interval = 15-295/100,000) for active cases would be representative for the rural population in high endemicity areas, the current number of AE cases in southwestern Germany is considerably higher than previously suspected.
The risk of Borrelia burgdorferi infection and the value of antibiotic prophylaxis after tick bite are controversial. In this study, performed in two areas of southwestern Germany, ticks were collected from 730 patients and examined by the polymerase chain reaction (PCR) for B. burgdorferi. To assess whether transmission of B. burgdorferi occurred, the patients were clinically and serologically examined after tick removal and during follow-up examinations. Data from all tick bites gave a total transmission rate of 2.6% (19 patients). Eighty-four ticks (11.3%) were PCR positive. Transmission occurred to 16 (26.7%) of 60 patients who were initially seronegative and could be followed up after the bite of an infected tick. These results indicate that the transmission rate from infected ticks in Europe is higher than previously assumed. Examination of ticks and antibiotic prophylaxis in the case of positivity appears to be indicated.
Three molecular typing methods, repetitive-sequence-based PCR (rep-PCR) fingerprinting, plasmid profiling, and arbitrarily primed PCR fingerprinting, were used to characterize isolates of Salmonella enterica serovar Saintpaul. Most of the isolates were obtained from epidemic human cases of food-borne salmonellosis, together with some from the food material suspected to be the source of infection, and a few were obtained from other cases apparently not related to the epidemic. All three methods adequately discriminated the epidemic strain from other strains of the serovar. In addition several isolates from human cases which are not identical to the epidemic strain were found. These isolates therefore must have been responsible for some sporadic infections, which were only temporally related to the epidemic. These strains showed a high degree of similarity to a strain isolated from a turkey. rep-PCR fingerprinting with REP-Dt primers and primer ERIC1R, applicable even to crude cell lysates, offers an attractive choice as a primary method for the discrimination of various Salmonella serotypes as well as isolates within serotype Saintpaul.
In order to elucidate the epidemiological importance of hemorrhagic fever with renal syndrome in Germany, the prevalence of antibodies against hantaviruses was determined in 13,358 sera from residents of various geographic regions, 1,284 sera from occupational risk groups and 287 sera from chronic hemodialysis patients. Serological investigations were performed using a highly specific transferable solid phase enzyme immunoassay based on the recombinant nucleocapsid proteins of a Hantaan and a Puumala serotype strain. The overall antibody prevalence was found to be 1.68%. In the serum panels from western and southern Germany, it was determined to be 1.83% on average in contrast to only 0.8% in the panel from eastern Germany. An endemic focus revealing an antibody prevalence of 3.12% was detected in a low-mountain area called Suebian Alb, which is located in the federal state of Baden-Württemberg. Occupational risk groups and a group of chronic hemodialysis patients showed a significantly elevated antibody prevalence ranging from 3.3% to 10%. The Puumala serotype was found to be the prevailing virus, but the percentage of sera predominantly recognizing the Hantaan nucleocapsid protein increased towards the south and the east and was significantly elevated in dialysis patients.