Acta Leidensia最新文献

This review focuses on parasite enzymes which are involved in the detoxification of oxygen radicals, and covers the following enzymes: superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase and glutathione reductase. These enzymes are crucial for parasites to evade oxygen-mediated attack by host leukocytes, both intracellularly and extracellularly. In addition, the newly defined parasite system involving trypanothione, trypanothione peroxidase and trypanothione reductase is discussed.

A cysticercus antigen was purified from the membrane. It is a glycoprotein containing hexoses and sialic acids with a molecular weight of 70 Kd and isoelectric focussing point 4.8. In western blot studies, the purified antigen bound with antibodies present in cerebrospinal fluid of all neurocysticercosis patients tested. Amino acid composition of the antigen showed a high content of Glutamate, Leucine and Aspartate while Proline and Hydroxyproline were absent. When cysts recovered from pigs were cultured for eight days, the excretory-secretory antigen obtained bound strongly with the antibody raised against the purified antigen. This indicates the homology of the two antigens. The possibilities of using this antigen for vaccination are discussed.

In april 1987, an epidemiologic study in Northern Togo was carried out in order to evaluate the prevalence of cysticercosis and epilepsy. The survey also aimed to investigate possible connections between these two illnesses. The study encompassed 5264 subjects over 15 years old, selected using random sampling techniques; 125 cases of cysticercosis were diagnosed (2.4% of sample population); 12 by anatomo-pathological examination of cysts 18 (14.4%) based on skull and muscle x-ray calcifications and 104 patients were identified using ELISA tests on 1527 serum samples (optical density greater than or equal to 0.4). Among 88 epileptic patients (prevalence = 16.7 per thousand), 27 also suffered from cysticercosis (38.7% of all epileptic patients, 21.6% of cysticercosis patients and 0.51% of the total population).

A preliminary report of praziquantel (PZQ) treatment in 10 patients with cysticercosis in Vietnam is presented in this paper. One patient with a severe neurological disorder probably died due to increased intracranial pressure. Nine patients were treated with relatively low dose of PZQ (15-20 mg/kg). Almost all subcutaneous cysts disappeared while patients with neurological symptoms definitely improved. However, more or less severe side effects were observed during the treatment course in spite of concurrently applied corticosteroids. The patients are still under follow-up attention.

After a historical introduction to the Ostertagiinae and several revisions of this group, it is proposed that the subfamily shall contain seven genera: Ostertagia, Hyostrongylus, Longistrongylus, Marshallagia, Mazamastrongylus, Spiculopteragia and Teladorsagia. The synonyms of these genera are to be found in the literature. In this proposal the genus Hyostrongylus should belong to the Ostertagiinae though it has probably an intermediate position between the Ostertagiinae and Graphidiinae. Cervicaprastrongylus and Tunisostertagia are regarded as synonyms of Hyostrongylus and Ostertagia respectively. The position of Ostertamia and Trichostrongyella is not clear but they could have their closest affinities with Teladorsagia and Mazamastrongylus respectively. The origin of the subfamily and the relationships of the genera with regard to their preferences for host groups and to their geographical distribution are discussed.

Progress in recent research towards vaccination against cysticercosis is reviewed briefly. An antigen of Taenia ovis has recently been cloned using recombinant DNA techniques and this single defined recombinant molecule has been shown to induce high-level protection against challenge infection in sheep. Prospects for the application of this discovery in T. ovis for development of effective vaccines against infection with the metacestodes of other taeniid parasites are discussed. The extent and level of cross protection between different taeniid species is reviewed. Recent research results defining stage-specific immune responses against T. taeniaeformis in mice following immunization with oncosphere and metacestode antigens is discussed in relation to the potential development of cocktail vaccines. Such vaccines may be capable of protecting against initial infection and the killing of those parasites which might evade the early-phase immune responses. Recent advances in the development of a practical vaccine against Taenia ovis infection in sheep raise the realistic prospect of the development of a similar vaccine against other taeniid parasites including T. solium. Advances in the understanding of vaccination - induced immune responses against T. taeniaeformis infection in mice also indicate that effective immunization may be capable of eliminating the establishment of any viable metacestodes.

The influence of the novel hydroxynaphthoquinone 566C80 on exoerythrocytic development of Plasmodium berghei was examined in Brown Norway rats. The procedure employed was designed to identify residual activity of the drug against tissue merozoites emerging into the bloodstream and to distinguish this from any observed causal prophylactic activity against the liver stages. Single oral doses of 10 and 1 mg/kg of 566C80 administered 3 hours after sporozoite-inoculation were effective in preventing the appearance of a patent parasitaemia, while a dose of 0.1 mg/kg significantly reduced the severity of the ensuing blood infection. There was a pronounced residual effect of 566C80 against the blood forms at a dose of 10 mg/kg, a slight residual effect at a dose of 1 mg/kg, but no apparent residual effect at 0.1 mg/kg. At the time when EE merozoites would normally emerge into the bloodstream, an aliquot of blood was sub-inoculated into mice from sporozoite-infected, 566C80-treated rats. This procedure confirmed that 566C80 is active against the exoerythrocytic stages of Plasmodium berghei.

A study was carried out in a rural community of the state of Guerrero in order to find ways to control human taeniasis/cysticercosis (Taenia solium). At the beginning of the study the frequency of porcine cysticercosis was established to be around 6.6%. Fecal examination in the human population showed that of 760 persons, 24 were carriers of Taenia sp (3%). Of 440 human sera tested for antibodies against cysticercus cellulosae, 9 showed absorbance values of 0.2 or higher (2.3%). 900 persons received treatment against taeniasis. 400 soil samples and 600 flies were examined for the presence of eggs of Taenioae, all with negative results. Meetings with the adult population were organized to explain the disease and the life cycle of the parasite. Lectures and demonstrations for adults were given at the school for primary and secondary grade children. Special emphasis was given to the need to construct latrines in every home, as it was found that defaecation was practiced mainly in the open, usually at places where pigs had immediate access and ingested the faeces. One year after the initiation of the programme, pigs under the age of 1 year were inspected, to determine whether the cestocide treatment of humans has had an effect on the degree of parasitized pigs and if hygiene had improved. 11% of these animals were found to have cysticerci in their tongue. Two years after the initiation of the programme 78% of the children and 2% of adults answered questions about the lifecycle of the parasite correctly. The results of the trial are discussed and suggestions for future programmes are made.