Biomedical subjects
Publications and source records attributed to P Kimmig.
PCR was used to detect and specifically identify a gene fragment from Cryptosporidium parvum. An 873-bp region of a 2,359-bp DNA fragment encoding a repetitive oocyst protein of C. parvum was shown to be specifically amplified in C. parvum. An excystation protocol before DNA extraction allowed the differentiation between live and dead Cryptosporidium parvum oocysts.
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The role of mineral thermal baths and particularly of bath fittings such as benches and toilet seats in the spreading of Trichomonas vaginalis is controversial. In order to clarify the possibility of transmission by smear infection of this ubiquitous urogenital parasite the ability to survive was investigated in 11 mineral baths in Baden-Württemberg by contamination of water samples of varying mineral content. In addition, Trichomonas-contaminated water samples were placed in Petri-dishes on different benches in the bath area to determine the different milieu-factors influencing survival and thus the possibility of smear infections. The determination of viable cells was carried out by recultivation and semiquantitative extinction measurement. The survival time of Trichomonas vaginalis in the water samples of the 11 mineral baths varied considerably from 30 min up to more than 3 hours. The total mineral content played the most important role. When exposed in Petri dishes in addition the evaporation of the medium (mineral water) is of importance. Generally at high evaporation rates the cells will lose viability faster than in closed tubes. But also in open dishes in 4 mineral baths viable Trichomonads were still detectable after 3 hours. Generally the ability of Trichomonas vaginalis to survive in water of a total mineral content of 0.05-2.2% is increased to such an extent that infection is theoretically possible. Transmission in the mineral pool itself appears nevertheless highly unlikely due to the dilution effect of the enormous water volume. However transmission of infection via wet, contaminated benches and toilet seats cannot be generally ruled out.
Cysts of Echinococcus multilocularis were found in the massively enlarged liver of an 18 month old Crab-eating macaque (Macaca fascicularis) at post mortem examination. The infection was diagnosed by macroscopic inspection, histological examination and the shape of the hooks of the protoscolices. This is the first description of a fox tapeworm infection in an Old World monkey. The animal had lived in a recreational park situated in an E. multilocularis endemic region. The special epidemiology of this case is discussed.
Ocellate furcocercariae from the lymnaeid snail Radix auricularia have been identified as causative agents of swimmer's itch, which has become increasingly common in the 'Tunisee' near Freiburg. On an average 11.0%, maximally 25.0%, of the snails were parasitized with these trematode larvae. The Trichobilharzia parasitizing rate in the intermediate hosts found here was thus approximately 10-100 times higher than the Trichobilharzia prevalence described so far. Dwarf mallards (Anas platyrhynchos, blood red) were experimentally infected with Trichobilharzia cercariae from the 'Tunisee'. From the 13th day p.i. miracidia could be found in their faeces by means of the hatching method. The trematode eggs had the shape of an elongated spindle, with a pointed and a rounded end. The sexually differentiated adult worms were localized only in the hepatic and enteric veins. They had an average length of 4.0 mm (3.2-4.6 mm) and a width of 125 microns. Their tegument was strongly folded and had tegumental spines in the oral and ventral suckers, in males in addition along the canalis gynaecophorus. The most striking internal organ was the gut filled with hematin and separated in 2 caeca at its anterior end. Its form and localisation as well as those of the sexual organs were important criteria for the differentiation of the different Trichobilharzia species. The Trichobilharzia species found in the 'Tunisee' clearly differed from Trichobilharzia szidati both morphologically and physiologically. The latter has been considered, until now, to be the main causative agent of swimmer's itch in Germany. Moreover, the adult trematodes from the 'Tunisee' could not be associated with any other species of this genus. We propose therefore the name Trichobilharzia franki n. sp. for the species from the Tunisee.
Cases of swimmer's itch caused by cercariae of the genus Trichobilharzia have spread during the last years in Southwestern Germany and increased in intensity. The only consequence was to forbid swimming because no effective strategies are known which would be ecologically or financially acceptable. In this examination we therefore tried, by means of medication of ducks, the possible final hosts, to kill the different stages of Trichobilharzia in patency and prepatency in order to interrupt the parasitic cycle. For this the effectiveness of praziquantel on the parasitic stages in the final host (preadults, adults, eggs or fully developed miracidia) was tested in experimentally infected dwarf mallards (Anas platyrhynchos, hemerot.) and mallards (Anas platyrhynchos platyrhynchos). During therapy of ducks with patent Trichobilharzia infection, onefold or twofold application of this drug (1 x 500 mg/duck, 1 x 300 mg/duck, 2 x 200 mg/duck) only prevented the releasing of eggs with hatchable miracidia for up to 24 h. Only a threefold application of 200 mg/duck in 24 h intervals led to a permanent reduction of detectable miracidia. Application of praziquantel in low doses (30 or 40 mg per duck and day) did not reduce the number of released miracidia. Medication with praziquantel led to a strong shift of adult worms located in the enteric veins of the ducks to the liver veins in a little as 3 h; examinations by scanning electron microscopy revealed changes in the worms' surface and damage of the tegument. During prepatency doses of 22.5 mg praziquantel per duck and day, given continuously for one week, were sufficient to completely stop the release of miracidia. In this low dosage, a special preparation of the bitter drug was voluntarily swallowed by the ducks, thus providing in principal a simple, cheap and ecologically sound method of controlling cercarial dermatitis.
Cryptosporidium parvum and Giardia lamblia are protozoan parasites which can cause gastroenteritis in man and animal. Surface water and drinking-water play an important role in transmission of the disease. The parasites can be detected by extensive and time-consuming procedures only. In this paper we describe a new way to isolate C. parvum and G. lamblia from water by a modification of essential steps of the original method of Rose. The new method applies the separation by flow centrifugation, the purification by different filters and the parasite isolation by percoll density gradient centrifugation. The modified method allows reproducible and by 20% increased recovery rates of cysts. Due to this fast and easy technique this procedure can be integrated in routine examinations.
People of Southern Germany as well as European and non European asylum applicants were examined for Toxocara-infection by means of an ELISA with excretory/secretory antigen of Toxocara canis-larvae; in default of a reference method the cut off was defined statistically. In the Stuttgart area, the average seroprevalence of healthy blood donors was 4.8%; children aged 1-7 years showed a seroprevalence of 2.1%. However the low percentage in children sera is probably not the effect of a lower risk of infection, but may result from the fact that most of the tested children live in city areas. Non-Europeans and Eastern Europeans showed a significantly higher seroprevalence (13.7% or 17.7% respectively) in comparison to the blood donors from Southern Germany. This indicates a higher risk of infection in these countries. It was possible to determine the different risk factors for a Toxocara canis-infection with some of the test-participants in Southern Germany. Compared to the low-risk-group (seroprevalence 1.9%), the test groups with risk factors showed a significant increase in seroprevalence: dog-owners 5.6%, owners of domestic cattle 9.4%, cat owners 10.9%, farmers 22.6%. In the presence of several risk factors an additive effect on the seroprevalence could be found: In the test group with one risk factor the seroprevalence (9.2%) was lower than in the test groups with two (10.8%) or three risk factors (18.6%). Considering the high prevalences found in this study and the possible dangerous complications of Toxocara canis-infections, medical and hygienic measures seem to be advisable.
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By intravenous (i.v.) inoculation of living tuberculosis bacteria (BCG) non-specific resistance to microfilariae of Litomosoides carinii (Filarioidea) is induced in cotton rats. This is only possible using the preparation "Immune-BCG Pasteur F" (suspended germs), but not with "Vaccin-BCG pour scarifications" (lyophilized tuberculosis bacteria). After inoculation of Immune-BCG, followed by a challenge infection by 60 infective larvae 6 weeks later, a patent infection develops. However, the level of microfilaraemia is constantly lower than in the control. After challenge infection 12 weeks later, this effect has disappeared. Immune-BCG has no influence on the worm load or the output of microfilariae by the adult worms. If i.v. inoculation of Immune-BCG is combined with a subcutaneous injection of specific antigen--living embryos from the uteri of adult worms--the BCG-activated immune system undergoes specific sensitization. Upon challenge infection 6 weeks later, the microfilaraemia is completely suppressed, but the worm load and production of microfilariae by the adult female worms are normal. If Immune-BCG is injected i.v. 3 days before intraperitoneal injection of freeze-killed microfilariae, there is still constantly reduced microfilaraemia when challenge infection follows 12 weeks later. Obviously, the effect of this relatively weak antigen may be increased by BCG stimulation.
The infestation by the larva of Echinococcus multilocularis, also known as alveolar echinococcosis, is the most dangerous parasitic disease of man in Middle Europe. This is due to the location in the liver but still more so because of the proliferative and infiltrating growth of the larval tissue. The basic infective cycle of the parasite is a zoonosis between foxes as final hosts and small rodents such as common voles as intermediate hosts. Man can be a false intermediate host and thus a carrier of the larval stage. The infection arises from oral ingestion of the tapeworm eggs either on wild berries or in dust. Dogs and cats are a further important source of infection. They can be facultative carriers of adult E. multilocularis and are thus able to excrete eggs or proglottids of the tapeworm. In west Germany, in particular the "Schwäbische Alb" must be regarded as an endemic region for E. multilocularis. According to the examinations of Zeyhle, the infection rate of foxes here is more than 15% on an average, in some local areas as for example in the district of Reutlingen it is over 25%. In order to estimate the danger of infection for man in hyperendemic areas the population of two villages of this district and also specially endangered occupational groups (hunters, foresters) of the whole "Schwäbische Alb" have been examined for echinococcosis by serological means. A stepless ELISA was used as screening test. Thus circa 2200 persons liable to E. multilocularis could be examined. Among the population of the district of Reutlingen nine highly suspective sera could be detected. Computer tomography of these nine persons showed only one case of Echinococcus which could be identified as E. multilocularis after operation. Presumably serological positive cases come up as a consequence of a real contact with E. multilocularis. But in most cases the larval cestode tissue might soon degenerate because man is a relatively poor intermediate host. It cannot be excluded, however, that the Echinococcus-larva could not yet be identified clinically because of its early stage. According to most cautious estimation the prevalence of E. multilocularis in this endemic area might be one per thousand, the contact frequency, however, up to one per cent.
Swimmer's dermatitides occurring in natural--accordingly polluted--waters are most probably of chemical nature. In clean waters, however, they are primarily caused by larvae of duck-flukes, the so called cercariae. In a natural pool near Biberach undetermined cases of swimmers' dermatitis have appeared. Hence a cercarial dermatitis was suspected and specific examinations were carried out. At the biological examination of the pool, many watersnails of the species Radix ovata have been found near the shore. Out of 180 collected snails 8 produced cercariae of different trematode species. Hence an infective cycle between duck and snail could be ascertained here. However, the special cercariae, producing dermatitis, could not be found. Having taken that into account the author was standing in the snail biotop without protective clothes for about 1 hour to provoke cercarial dermatitis. A few minutes later the corresponding clinical picture with an extremely strong itching developed. Papules were to be seen 12 h later, the symptoms lasted 2 weeks altogether. By different serological methods (Cercarienhuellenreaction) indirect immunofluorescent test with complete cercariae and cercarial sections antibodies against cercariae could be demonstrated in the serum of the author 14 days later. As a therapy only the symptomatic treatment of the itching is possible. In principle etiologic measures against cercarial dermatitides are possible by chemical snail control. But as a rule this is to be refused because of the severe ecological damages. However, in case of swimmers' dermatitis it is nonetheless indispensible to clarify eventual parasitogenic reasons because of the specific hygienic consequences.
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After intracutaneous inoculation of BCG and challenge by subcutaneous injection of infective larvae of Litomosoides carinii, the parasitaemia of the filarial infection in cotton rats remains significantly lower when BCG and larvae are applied in the region of the same popliteal and ileal lymph nodes. However, when the infective larvae are directed to other regional lymph nodes (Ln cubitales and axillares), the depression of microfilaraemia is missed. The worm load (recovery rate) and the expulsion of microfilariae by the adult worms are not influenced by the BCG inoculation. Obviously BCG stimulates the lymphatic tissue unspecifically, and the infective larvae produce the first antigen contact, which is boostered by the microfilariae at the onset of patency. When the intracutaneous BCG inoculation is combined with specific antigen stimulation by simultaneous injection of blood microfilariae in the region of the same lymph nodes, the microfilaraemia of the challenge infection disappears completely or remains extremely low.
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Experimental filarial infections of Mastomys natalensis, strain GRA Giessen, with Litomosoides carinii, Dipetalonema viteae, Brugia malayi (subperiodic), and Brugia pahangi were compared. Mean prepatent periods of 52, 57, 107, and 73 days p.i. were observed after subcutaneous inoculation of 40, 50, 85, and 70 infective larvae of L. carinii, D. viteae, B. malayi, and B. pahangi, respectively, in the neck region. All of the L. Carinii, D. viteae, and B. pahangi infected Mastomys showed a regularly detectable microfilaraemia. In B. malayi infections 95.5% of the animals developed parasitaemias, when the larvae had been inoculated in the neck region, whereas after groin infections only in 66.7% of the animals became patient. For both Brugia species, infections in the groin resulted in considerably lower microfilarial levels. Maximum microfilariae densities could be detected at day 120 (L. carinii) and at day 1980 (D. viteae) p.i. In the case of Brugia neck infections, the microfilarial levels increased usually until the end of the observation period, 300-350 days p.i. Worm recovery rates were 63% (L. carinii), 20.6% (D. viteae), 21.1% (B. malayi), and 31.4% (B. pahangi) of the inoculated larvae. When third stage larvae of Brugia species were inoculated in the neck region, adults of B. malayi and B. pahangi were isolated predominantly from the heart of lungs (84.4 and 78.5%, respectively). Only 12.3% of B. pahangi parasites were found in the testes; 3.4% and 18.1% were localized in the lymphatics. After inoculation of infective larvae in the groin more worms could be recovered in the testes and lymphatics, i.e. 23.4% and 14.9% (B. malayi) or 19.1% and 45.2% (B.pahangi), respectively. The results are discussed under the aspect of chemotherapeutic investigations for the evaluation of microfilaricidal, macrofilaricidal or chemoprophylactic compounds. It is concluded, that Mastomys natalensis, an animal with a broad spectrum of susceptibility for filarial infections, can be used as an alternative experimental model system, similar to that of the jird.
A method is described to isolate microfilariae of Litomosoides carinii on a Ficoll isopycnic gradient. The simple and fast procedure yields a high percentage of microfilariae apparently without causing any alteration of the larval surface and vitality.