Variation in clinical and parasitological traits in Pietrain and Meishan pigs infected with Sarcocystis miescheriana

Future prophylaxis needs new concepts, including natural disease resistance of hosts against infectious agents. Genomic approaches to detect and improve disease resistance in farm animals and the molecular mechanisms involved in host-parasite interactions depend to a high degree on the trait differences between founder breeds, i.e. on the animal model. The present study evaluates differences in susceptibility/resistance against Sarcocystis miescheriana in the European Pietrain (PI) and the Chinese Meishan (ME) pig breeds, based on 25 individuals, infected orally with 5x10(4) sporocysts of S. miescheriana. Significant differences appeared in clinical, serological, haematological and parasitological findings. The major discriminating period post infection (p.i.) was between days 42 and 45. Severity of signs was negatively correlated with specific immunoglobulin titres during the first 3 weeks p.i. and positively with the load of bradyzoites in muscle tissues of the pigs. Loads of bradyzoites in muscle tissues were 20 times higher in PI than in ME. Sarcocystis-specific differences between the two breeds were in the range of 1-2 standard deviations. The study lays the foundation for further experiments to analyse chromosomal regions, candidate genes, and thus the molecular basis of Sarcocystis susceptibility/resistance as a model for host-parasite interaction in protozoan infectious disease.

Screening of dogs for Echinococcus granulosus coproantigen in a low endemic situation in Cyprus

In the framework of an echinococcosis surveillance and control programme in Cyprus, a commercial enzyme-linked immunosorbent assay (ELISA) (CHEKIT ECHINOTEST) designed for the detection of Echinococcus granulosus and E. multilocularis coproantigens was used in 1997-2000 for the investigation of large numbers of dogs. Most of the animals originated from areas where approximately 0.2% of the dogs had been found to be infected with E. granulosus in previous (1993-1996) arecoline surveys. The sensitivity of the coproantigen test was 83%, as determined in 35 dogs naturally infected with this cestode species. The specificity was 98% in 97 randomly selected dogs from Cyprus, but it was reduced to 80% in a group of 50 dogs, infected with Taenia spp. A total of 6551 dogs (mainly of rural origin) was examined, including three large groups (N: 2928, 1761 and 1800) from the Government Control Area (GCA) in southern Cyprus and a small group (N: 62) from the Non-Government Control Area (NonGCA) in the northern part of the island. Among the dogs from the GCA, 184 (2.8%) tested positive for coproantigen; coproantigen prevalences were 2.6, 4.9 and 1.1% in these three groups, and of 62 dogs from the NonGCA 8.1% were positive. The calculated true prevalences of E. granulosus in the dog population of the GCA ranged between 0.0 and 3.58%. The predictive values of the test, based on a 0.2% prevalence, was >99.9% for negative results, but very low (7%) for coproantigen-positive results. However, the relatively small number of coproantigen-positive dogs can be treated with praziquantel or the results can further be confirmed by arecoline purging.

Veterinary aspects of alveolar echinococcosis--a zoonosis of public health significance

Human alveolar echinococcosis (AE), caused by the metacestode stage of Echinococcus multilocularis, is a serious zoonosis which caused up to 100% lethality in untreated patients before the 1970s, when modern methods of treatment were not yet established. AE occurs in large areas of the northern hemisphere mostly with low country-wide prevalences, but high prevalences of up to 4% have been reported from small population groups in highly endemic foci, e.g. from China. AE includes many veterinary aspects which are the topic of this review. Recent studies have shown that E. multilocularis has a wider geographic range than previously anticipated. There is evidence for growing populations of red foxes (Vulpes vulpes) in some areas, for increasing invasion of cities by foxes and also for establishment of the parasite cycle in urban areas. These and other factors may lead to an increased infection risk for humans. Significant progress has been made in the development of sensitive and specific new techniques for the intra vitam and post mortem diagnosis of intestinal E. multilocularis infection in definitive hosts, notably the detection of coproantigen by enzyme-linked immunosorbent assay and of copro-DNA by PCR. Both tests can also be used for the identification of E. multilocularis in faecal samples collected in the environment. Recommendations are given for chemotherapy and chemoprophylaxis of the intestinal infection in definitive hosts. In recent years, infections with the metacestode stage of E. multilocularis have not only been diagnosed in humans in several regions, including at least eight countries in central Europe, but also in animal species which do not play a role in the transmission cycle (wild and domestic pigs, dogs etc.). From 1987 to 2000 our group in Zurich has diagnosed 10 cases of AE in dogs and 15 in captive monkeys. In 2 dogs, concurrent infections of the intestine and of the liver with adult and larval stages of E. multilocularis, respectively, were observed for the first time. Clinical data are presented, and methods of diagnosis and treatment (surgery, chemotherapy) are described. Furthermore, small liver lesions caused by E. multilocularis were diagnosed in 10% of 90 slaughter pigs, and 2.9% of 522 breeding sows had specific serum antibodies against parasite antigens. In view of the unpredictable epidemiological situation, all possible measures for preventing E. multilocularis infections in humans and in domestic animals should be initiated by the veterinary and health authorities.

Topological-histological investigation of the pterygium

BACKGROUND

It is a wide-spread assumption, never proven scientifically, that the pterygium is a duplication of the conjunctiva, with an intervening gap at the limbus. We therefore conducted a histological reinvestigation, primarily to clarify the topological relation between normal bulbar tissue and lesion.

METHODS

Excised pterygia were prepared for light microscopy and embedding in paraffin. Two pterygia were serially sectioned, and samples of 49 others were removed, sectioned and stained (stains: H&E, alcian blue, toluidine blue, PAS; antibody: cytokeratin 18).

RESULTS

The pterygium is an epithelium-covered protuberance of connective tissue, projecting over the normal surface of the eyeball; it consists of a base, which extends in the direction of growth, and lateral lobes. It is therefore impossible to insert a probe all the way under a pterygium. The bulbar tissue adjacent to the pterygial protuberance can likewise be histologically altered. That is, a narrow layer of connective tissue, well supplied with capillaries, may be present in the corneal section of the pterygium between Bowman's layer and the epithelium.

CONCLUSION

Histological alterations of the stroma predominate quantitatively over those of the epithelium. The topographical anatomy of the lesion and the fact that bulbar tissue is modified along with the pterygium should be taken into account when excision is undertaken. We predict that if all the altered tissue is removed, the rate of recurrence will be reduced.

Catalysis research of relevance to carbon management: progress, challenges, and opportunities

The goal of the "Opportunities for Catalysis Research in Carbon Management" workshop was to review within the context of greenhouse gas/carbon issues the current state of knowledge, barriers to further scientific and technological progress, and basic scientific research needs in the areas of H2 generation and utilization, light hydrocarbon activation and utilization, carbon dioxide activation, utilization, and sequestration, emerging techniques and research directions in relevant catalysis research, and in catalysis for more efficient transportation engines. Several overarching themes emerge from this review. First and foremost, there is a pressing need to better understand in detail the catalytic mechanisms involved in almost every process area mentioned above. This includes the structures, energetics, lifetimes, and reactivities of the species thought to be important in the key catalytic cycles. As much of this type of information as is possible to acquire would also greatly aid in better understanding perplexing, incomplete/inefficient catalytic cycles and in inventing new, efficient ones. The most productive way to attack such problems must include long-term, in-depth fundamental studies of both commercial and model processes, by conventional research techniques and, importantly, by applying various promising new physicochemical and computational approaches which would allow incisive, in situ elucidation of reaction pathways. There is also a consensus that more exploratory experiments, especially high-risk, unconventional catalytic and model studies, should be undertaken. Such an effort will likely require specialized equipment, instrumentation, and computational facilities. The most expeditious and cost-effective means to carry out this research would be by close coupling of academic, industrial, and national laboratory catalysis efforts worldwide. Completely new research approaches should be vigorously explored, ranging from novel compositions, fabrication techniques, reactors, and reaction conditions for heterogeneous catalysts, to novel ligands and ligation geometries (e.g., biomimetic), reaction media, and activation methods for homogeneous ones. The interplay between these two areas involving various hybrid and single-site supported catalyst systems should also be productive. Finally, new combinatorial and semicombinatorial means to rapidly create and screen catalyst systems are now available. As a complement to the approaches noted above, these techniques promise to greatly accelerate catalyst discovery, evaluation, and understanding. They should be incorporated in the vigorous international research effort needed in this field.

[Efficacy evaluation of epsiprantel (Cestex) against Echinococcus mutilocularis in dogs and cats]

Helminth-free dogs and cats were experimentally infected with protoscoleces of Echinococcus multilocularis and used in controlled trials for efficacy evaluation of the cestodicide epsiprantel. In two separate trials each 4 dogs were treated at day 20 post infection (p.i.) with average oral dosages of 5.1 (4.9-5.3) and 5.4 (5.2-5.8) mg/kg body weight (b.w.) epsiprantel, respectively, and necropsied at day 24 p.i. Among each 4 dogs of the two untreated control groups all animals were infected and had high intestinal worm burdens with averages of 33.575 and 100.725 E. multilocularis specimens per animal (individual worm burdens in group Ib 59,500-149,800, group IIb 20,500-43,200); in the two groups of treated dogs the average worm burdens were reduced by 99.6 and 99.9%. Among 8 treated dogs 4 were helminth-free, the other 4 had residual worm burdens (10-70 in 3 dogs, 1480 in 1 dog). In each 5 cats single oral treatments with average doses of 2.7 (2.7-2.8) and 5.5 (5.5-5.5) mg/kg b.w. epsiprantel were 100% effective against E. multilocularis 20 days p.i. and eliminated the worm burdens from all 10 animals. In the untreated group of 5 cats the average worm burden was 2864 per animal (individual worm burdens 20-6830). Side effects of the drug treatment were not observed. The results of the study show that in single therapeutic dosages recommended by the producer (dogs 5.5 mg, cats 2.75 mg/kg b.w.) epsiprantel eliminates E. multilocularis to over 99% or completely, but residual worm burdens may persist in some animals.

The "galloping" history of intermittent claudication

Intermittent claudication (IC) due to arterial occlusive disease was first diagnosed by the French veterinary surgeon Jean-François Bouley jeune in a horse drawing a cabriolet in the streets of Paris as early as 1831. The animal was repeatedly exercised and always started to limp with the hind legs at similar work loads. Autopsy revealed partially thrombosed aneurysm of the abdominal aorta and occlusions of both femoral arteries which were correctly identified as the cause of IC. In 1858 the famous neurologist Jean-Martin Charcot working at the Salpêtrière in Paris first discovered the condition in a patient, who was wounded by a bullet during the conquest of Algery and developed iliac artery aneurysm obliterated by a thrombus. He was aware of the first description in veterinary medicine. In Germany IC was also first mentioned in horses (Rademacher, 1838). 13 reports of patients were contributed by the neurologist Heinrich Erb in 1898 and 1904. Some interesting features of the phenomenon of IC like the amount of exercise necessary to provoke it, localization, social relevance, prolongation of the Achilles tendon reflex, decrease of maximal plantar flexion force of the foot and production of "Lewis factor p" are summarized. In human patients arteriosclerosis is the well recognized principal cause of arterial obstructions, in horses, however, the lesions are due to infection by the roundworm Strongylus vulgaris. In the fascinating life cycle the larvae migrate into the intima of small and large arteries and provoke aneurysms and intravascular thrombosis.

Echinococcosis: an emerging or re-emerging zoonosis?

The aim of this review is a critical discussion of factors actually or potentially contributing to persistence or emergence of echinococcosis in humans. Alveolar echinococcosis (AE), a life-threatening infection of humans, is caused by a larval stage of Echinococcus multilocularis. The adult parasite inhabits the intestine of foxes and other carnivores and has a wide distribution in the northern hemisphere (North America and northern and central Eurasia). Recent surveys in central Europe have extended the known geographical occurrence of E. multilocularis in foxes from four countries at the end of the 1980s to at least 11 countries in 1999. Cases of human AE previously regularly reported from only four countries are now recorded from seven countries, but the annual incidences are low. Since adequate information from earlier surveys is not available, it is not possible to conclude if the new findings reflect a recent extension of the parasite's range or just the first identification of hitherto unnoticed endemic areas. Evidence of parasite spreading has been reported from North America and Japan. Factors with the potential of enhancing the infection risk for humans in the future include increasing fox populations and parasite prevalences, progressing invasion of cities by foxes, the establishment of urban cycles of the parasite, and the spill-over of the E. multilocularis infection from wild carnivores to domestic dogs and cats. In view of the potential severity and fatality of AE in humans health authorities should initiate internationally coordinated countermeasures. Although control programmes against human cystic echinococcosis (CE), caused by E. granulosus, have been established in some countries and effective control strategies are available, the parasite has still a wide geographical distribution affecting many countries of all continents. Thus, human CE is persisting in many parts of the world with high incidences, and in some areas it is a re-emerging problem. For example, alarming increases of the number of human cases have been reported from Bulgaria and Kazakhstan, and the People's Republic of China. Progress in control can only be expected if health authorities attribute a higher priority to this disease and if all modern diagnostic and control options (for example vaccination of intermediate host animals) can be used.