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Biomedical subjects

F van Knapen

Publications and source records attributed to F van Knapen.

At least 109 records · Page 6Linked to original sources
PubMed1983

Visceral larva migrans: examinations by means of enzyme-linked immunosorbent assay of human sera for antibodies to excretory-secretory antigens of the second-stage larvae of Toxocara canis.

An enzyme-linked immunosorbent assay is described for the detection of serum antibodies to visceral larva migrans (Toxocariasis). Excretory-secretory antigens of the second-stage larvae of Toxocara canis were used as antigen to coat the polystyrene plates. With sera from patients high antibody titers were observed in both ocular and visceral disorders. Cross-reactions due to other parasitic infections could be excluded, including other migrating larval infections such as ascariasis, trichinellosis, strongyloidiasis, filariasis, and anisakiasis. In a small seroepidemiologic survey of healthy primary schoolchildren, a remarkably high percentage (7.1) reacted positively to this method. These children showed eosinophilia as compared to the seronegative group. The data were compared with those observed in other countries and the results prompt reconsideration of the significance of T. canis for public health.

Ascariasis↗
PubMed1982

Prevalence of antibodies to toxoplasma in farm animals in the Netherlands and its implication for meat inspection.

A serological survey on toxoplasmosis was carried out amongst horses, sheep, cattle, pigs and poultry in the Netherlands. Sera were obtained from slaughter animals and the results were compared with those of previous studies of this kind in the Netherlands. In horses and cattle the percentage of seropositive animals remained the same in the past 20 years. In sheep and particularly in pigs, however, a remarkable decline of seropositive animals was found. This is probably due to the age of the animals examined and a change in present day methods of farming. In poultry it was shown that only free scratching hens were seropositive in up to 30 per cent of the animals tested, whereas broilers and battery animals were seronegative. Since as yet no individual control measures in the slaughterhouse exist with regard to toxoplasmosis it is recommended to carry out periodic epizootiological surveys amongst farm animals to be able to follow trends of the infection.

Abattoirs↗
PubMed1982

Detection of toxoplasma antigen in tissues by means of enzyme-linked immunosorbent assay (ELISA).

An enzyme-linked immunosorbent assay (ELISA) for the detection of free toxoplasma antigens in patient sera was applied for demonstration of toxoplasmosis in tissues. Unfixed organs stored at room temperature remain antigen-positive for weeks, even when parasites are no longer demonstrable by means of direct immunofluorescence testing. Chronically infected brains, containing tenths of cysts do not react positive, whereas recently infected brains (proliferative stage) are positive, suggesting that with this ELISA method discrimination can be made between different stages of the infection.

Animals↗
PubMed1982

Detection of specific immunoglobulins (IgG, IgM, IgA, IgE) and total IgE levels in human trichinosis by means of the enzyme-linked immunosorbent assay (ELISA).

Sera from 58 cases of confirmed human trichinosis were examined over an 11-month period. The enzyme-linked immunosorbent assay (ELISA) was used for the detection of class-specific serum antibodies (IgG, IgM, IgA, IgE) and for total serum IgE. The indirect immunofluorescent test served as reference technique. The ELISA proved to be more sensitive. Specific IgG antibodies were detected by ELISA in 100% of the clinical cases. Both IgG and IgM were demonstrable throughout the observation period of 11 months. Specific serum IgA was seen in 62% of the patients during the first 3 months, presumably the result of stimulation of the immune system by the adult worms in the intestine. Specific serum IgE was seen in a few cases only at the onset of the disease. Total serum IgE levels were elevated in 32% of the patients in the first month of the disease and in 17% after 11 months, compared to 10% of healthy individuals.

Antibodies↗
PubMed1981

Comparison of four methods for early detection of experimental Trichinella spiralis infections in pigs.

Four methods employed in the diagnosis of experimental porcine trichinellosis (trichinoscopy, digestion method, immunofluorescence and enzyme linked immunosorbent assay (ELISA)) were compared by eleven laboratories in the countries of the European Economic Community and Sweden. The aim of this study was to test the reliability of ELISA during the onset of T. spiralis infection. Material from conventionally raised pigs infected with 1500 to 10000 larvae was compared to uninfected controls at Day 17 and Day 21 post infection. The serological techniques gave higher percentages of positive results than the direct techniques. Specific antibodies could be demonstrated with ELISA at an earlier stage and at higher percentages than with the other methods. ELISA micro-assay was the most sensitive procedure.

Animals↗
PubMed1979

Food-borne parasitic infections--old stories and new facts.

A review is presented of food-borne parasitic infections. Parasitic infections with public health hazards both from conventional slaughter animals and from seafood (fish and shellfish) are discussed. The former category includes cysticercosis, echinococcosis, and trichinosis, the latter category covers various trematode, cestode, nematode, and possibly also protozoan infections. Examples of trematode infections are heterophyidiasis, transmitted to man by marine fish, and Paragonimus spp parasites, transmitted by crustaceans. Cestode infections include diphyllobothriasis transmitted by both fresh water fish and fish from brackish waters. Special attention is drawn to the condition known as sparganosis. Of the nematode infections, the eosinophilic granulomatous enteritis due to the genera Anisakis, Phocanema, and Contracaecum, transmitted to man by either marine fish or crustaceans, is mentioned. Two other nematode infections. Angiostrongylus cantonensis and Capillaria philippinensis, can also be transmitted to man by marine fish. Free living amoebae (a.o. Naegleria) may be transmitted to man via shellfish as vehicles. Apart from a possible direct effect of these parasites, chemical alterations in seafood resulting from the presence of parasites may also be deleterious to the consumer. Special attention is drawn to a newly developed serological detection method, the enzyme-linked immunosorbent assay, which makes detection of infection possible not only at the slaughterhouse but also at the farm or in large herds. Strategies to control parasitic infections both in conventional slaughter animals and in seafood are discussed.

Animals↗
PubMed1979

Dermatomyositis and toxoplasmosis.

In a patient with childhood dermatomyositis, high toxoplasma antibodies were found at the time of diagnosis. A direct immunofluorescence technique demonstrated active toxoplasmosis in the muscle biopsy. The response to treatment and follow-up in this patient suggest that toxoplasmosis could have caused the dermatomyositis.

Child↗
PubMed1977

The enzyme-linked immunosorbent assay and its application to parasitic infections.

The enzyme-linked immunosorbent assay (ELISA) was used for the serodiagnosis of four parasitic infections. ELISA was performed as a macromethod in polystyrene tubes and/or as a micromethod in polystyrene microplates. Conventionally raised pigs were infected orally with different numbers of Trichinealla spiralis larvae, and the pigs' sera were tested for antibody to T. spiralis. Results were compared with those from sera of uninfected conventionally raised pigs. Cynomolgus monkeys were infected orally and immunized with Toxocara canis. The results of macro-ELISA and micro-ELISA were compared with those of immunofluorescence. Micro-ELISA proved to be more sensitive than macro-ELISA, the latter being more sensitive than immunofluorescence. The applicability of ELISA for seroepidemiology was demonstrated by results obtained with sera from patients with proved African trypanosomiasis. With both macro-ELISA and micro-ELISA it was possible to discriminate between the positive and negative sera. ELISA was used for study of the seroepidemiology of toxoplasmosis. Again, positive sera could be distinguished from negative sera. The examples presented show that ELISA can be used as an additional serologic tool for the detection of both helminthic and protozoal infections.

Animals↗
PubMed1977

Detection of circulating antigen during acute infections with Toxoplasma gondii by enzyme-linked immunosorbent assay.

The serodiagnosis of toxoplasmosis is usually based on demonstration of antibodies by means of different serological methods. However, for confirmation of active toxoplasmosis, examination of paired sera is still needed. In this study a description is given of a sensitive enzyme method (enzyme-linked immunosorbent assay) with which it is possible to detect circulating antigens during the acute stage of mouse and human toxoplasmosis. Preliminary investigations of human sera suggested that circulating antigens are only found during a short period (active phase) of the toxoplasma infection and that they can be found in cases of fresh infections as well as during reinfections. The possible clinical relevance is discussed.

Animals↗