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Cerebrospinal nematodiasis in a goat herd.

During the fall of 1985, 4 Angora goats, from a herd of 40, were examined on a farm in central Michigan. Affected goats were alert but had neurologic deficits consistent with upper and lower moto neuron involvement. Eosinophilic pleocytosis in a cerebrospinal fluid sample from one goat was consistent with cerebrospinal nematodiasis. Parelaphostrongylosis was confirmed in 3 goats by identification of Parelaphostrongylosis tenuis larvae in spinal cord sections. Ivermectin may have influenced the herd's susceptibility to new parasitic infections. Control of parelaphostrongylosis probably is best achieved by removal of susceptible animals from treed swamps coinhabited by white-tailed deer from late summer until after the first killing frost.

Animals↗

Role of L3T4+ and LyT-2+ cells in experimental visceral leishmaniasis.

In contrast to euthymic (nu/+) BALB/c mice, athymic nude (nu/nu) BALB/c mice fail to control the visceral intracellular replication of Leishmania donovani, do not generate the macrophage-activating lymphokine IFN-gamma, and show little or no granulomatous tissue response. To characterize the T cell requirement for successful defense against L. donovani, nude mice were first reconstituted with unfractionated nu/+ immune spleen cells, which readily conferred the capacity to control and eliminate visceral (hepatic) L. donovani. In reconstituted mice, acquired resistance was paralleled by the ability of spleen cells to generate high levels of leishmanial Ag-stimulated IFN-gamma and the development of well formed liver granulomas. In contrast, nude mice reconstituted with either L3T4+- or Lyt-2+-enriched immune spleen cells alone failed to control visceral parasite replication and did not develop effective granulomas despite the finding that transfer of L3T4+ cells largely and Lyt-2+ cells partially restored the capacity to secrete IFN-gamma. To determine whether both T cell subsets were also required in a normal host, nu/+ BALB/c mice were treated with cell-depleting anti-L3T4 and anti-Lyt-2 mAb. Depletion of either T cell subset inhibited the acquisition of resistance to L. donovani and impaired the tissue granulomatous response. Thus, successful T cell-dependent host defense towards intracellular L. donovani and the tissue expression (granulomas) of this mechanism appear to require both L3T4+ and Lyt-2+ cells. A primary role for the L3T4+ cell may be IFN-gamma production; the role of the Lyt-2+ cell and the precise interaction of the two T cell subsets remain to be identified.

Animals↗

Vector control of filariasis in the Solomon Islands.

In Solomon Islands, filariasis is caused by the nocturnally perodic form of Wuchereria bancrofti and is transmitted by the same vectors of malaria. This study explores the control of this disease as an additional effect of the Malaria Eradication Programme.

Adolescent↗

Serum immunoglobulin E levels in onchocerciasis: the development of a radioallergosorbent test for Onchocerca volvulus infection.

The effects of Onchocerca volvulus infection on immunoglobulin levels have been studied in subjects from three localities with different onchocerciasis prevalence rates. Infestation by O. volvulus provoked a 200-500% rise in total serum IgE levels. Immunoglobulins G, M. and A were increased less dramatically. To study further the IgE response, radioallergosorbent test (RAST) systems were developed using total extract of O. volvulus and Onchocerca supernatant (excretory-secretory) antigens. Both antigen preparations reacted with more than 80% of the onchocerciasis sera from the hyperendemic village, but the reactions were not proportionate to skin microfilarial density. There were also positive reactions with sera of some individuals whose skin biopsies showed no microfilariae, indicating prior exposure to the parasite. European control sera tested under similar conditions reacted only slightly in the RAST system. The developed RAST systems may thus be used for determining prior exposure to O. volvulus.

Cameroon↗

Cryptic epitope explains the failure of a monoclonal antibody to bind to certain isolates of Trypanosoma cruzi.

A mouse monoclonal antibody, WIC 29.26 Ab, has previously been characterized as recognizing a carbohydrate epitope on a 72,000 m.w. glycoprotein (GP72) expressed on the surface of Trypanosoma cruzi epimastigotes and metacyclic trypomastigotes. This molecule has been implicated as a receptor in the control of parasite transformation, and when used as an immunogen in mice, partially protects against T. cruzi infection. In previous experiments in which a radioimmunoassay was used, WIC 29.26 Ab was found to react with approximately 50% of T. cruzi strains and clones derived from a variety of sources. In this study, we attempted to determine whether the WIC 29.26 Ab-nonreactive isolates lack the entire GP72 or merely lack the epitope recognized by this monoclonal antibody. WIC 226.4 Ab, a monoclonal antibody raised against periodate-treated GP72, reacted in an immunofluorescence assay with all strains and clones studied, including those which had not reacted with WIC 29.26 Ab. Likewise, two polyvalent rabbit sera, directed specifically against GP72, bound to all T. cruzi isolates tested. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of detergent lysates of surface-labeled epimastigotes immunoprecipitated with WIC 29.26 Ab showed that the epitope bound by this antibody was present in all but one of the parasites that were surface-nonreactive, as well as in all those that were surface-reactive. WIC 29.26 Ab precipitated a single 72K Mr band from most strains and clones, but in several cases 79K Mr and 66K Mr bands were seen. Isolates from both the surface-reactive and the surface-nonreactive groups showed the latter pattern. These results demonstrate that GP72, or similar electrophoretic variants--and with one exception, the carbohydrate epitope bound by WIC 29.26 Ab--are present in the surface membrane of all strains and clones tested. This observation suggests that in intact epimastigotes of the surface-nonreactive isolates, the epitope is not accessible because of structural changes in the molecule itself or because of differences in the membrane environment of GP72.

Animals↗

Antibody response to stage-specific Trichinella spiralis surface antigens in strong and weak responder mouse strains.

The antibody response to antigens on the cuticular surface of Trichinella spiralis was compared in two strains of mice, NIH mice, which control the parasite relatively strongly, and C3H, which reject this nematode more slowly. The evolution of the antibody response to the nematode surface was monitored by the appearance of antibodies that mediate the adherence of eosinophils to the worm and the appearance of antibodies that recognize molecules on the surface that can be labeled with 125I. Antibody responses were measured using three life cycle stages; muscle stage larvae, immature and mature intestinal stages, and newborn larvae. We found that NIH mice responded immunologically to the four molecules found in extracts of surface-labeled T. spiralis adult worms, but that C3H mice did not produce antibodies to one of these molecules until much later in the infection. NIH mice produced antibodies against both infective larvae antigens by day 4 after infection, whereas C3H recognized only one before day 30. Variations in antibody response also occurred against antigens on the surface of newborn larvae: antibody to one of these antigens was not present in C3H immune sera until day 30. Sera from the two strains likewise differed in their ability to mediate eosinophil adherence to each parasite stage, and in some of the life cycle stages, these differences corresponded to the recognition of specific antigens found on the parasites' surface. The links between recognition of defined parasitic antigens and the fate of the parasite in genetically different strains of mice are discussed.

Animals↗

Further studies on the anthelmintic effect of a sustained release pre-grazing treatment with morantel in grazing cattle in Sweden.

The efficacy of a morantel sustained release bolus (MSRB) to control gastrointestinal parasitism in first season grazing cattle was assessed under field conditions in Sweden. The MSRB was administered orally to calves immediately prior to turnout onto spring pastures in May, 1979, or in mid-season (July). The level of pasture contamination with infective larvae was reduced by 99 per cent in September by treatment at turnout. The corresponding figure was 89 per cent when the MSRB was administered in July. There was a 95 per cent reduction in worm burdens acquired over the entire grazing season in cattle treated in the early season and a 44 per cent reduction in worm burdens of cattle treated in the mid-season. During the 132 days grazing period a 19.1 kg (p less than 0.01) mean weight gain advantage was achieved by the early season treated animals, while a 10.0 kg mean weight gain advantage was achieved by the mid-season treatment. The weight gain advantage at the end of the grazing season in the early treated cattle increased continually during the winter with a resultant mean difference of 44.4 kg (p less than 0.01) by April 1980. Over the same period the mean weight gain advantage of the mid-season treated animals gradually fell to a final of 5.5 kg.

Animals↗

Coccidia parasitism increases resistance of mice to subcutaneous inoculation with Salmonella abortus ovis.

Resistance of outbred mice to subcutaneous challenge with S. abortus ovis was increased when previously or simultaneously parasitized with Eimeria Falciformis. This was measured by mortality rates and levels of splenic infection induced by Salmonella in parasitized and control NMRI or CD-1 (CR) mice. No effect was observed when E. falciformis was inoculated after S. abortus ovis.

Animals↗