Long-term observations on mouse strains experimentally infected with Angiostrongylus costaricensis.

BALB/c and C57BL/6 mice were experimentally infected with Angiostrongylus costaricensis and the parasitic parameters and antibody response during the acute and chronic phases of infection were analyzed. Following administration of six third-stage larvae (L3), there was no significant difference in the mean worm recovery or mean larval output. Coinciding with the maturation of worms in infected animals and with the egg output in mesenteric arteries, a strong increase in the humoral immune response was observed in both mouse strains. This response was characterized by a hypergammaglobulinemia, with a predominance of IgA and IgG1 during the acute phase of infection, and IgG1 and total IgE during the patent and post-patent periods. Significantly higher levels of IgM, IgG and IgG1 were found in BALB/c mice compared with C57BL/6 mice. On the other hand, a significantly higher concentration of IgA was detected at 6 and 7 weeks post-infection in C57BL/6 mice compared with BALB/c mice. Specific IgE could not be detected in any of the mouse strains. Our results suggest that immunoglobulins, mainly IgG1, contribute to the outcome of a primary A. costaricensis infection with respect to the period of patency and to mortality during the chronic phase.

The granular forms of the leprosy bacillus

The leprosy bacillus, like other acid-fast bacilli, produces in its evolutionary cycle great numbers of granular forms which are found both within the bacilli and as free-lying bodies. These granules constitute an essential phase in its evolution. Among the free-lying forms are those of all sizes down to the limits of visibility, so that it is probable that still smaller, perhaps invisible and filterable forms exist, which may be of special though as yet unknown importance in the pathology and epidemiology of the disease. The supposition is feasible that many of these granular forms are phenomena of degeneration and disintegration, which are determined in part by the defensive substances of the organism and in part by the action of our medicinal products, and especially by the chaulmoogra oil; therefore, their presence can be considered a favorable sign. Howevwe, a careful study of the granular forms suggests that they should not be considered solely as degenerative forms. Evidence is given that in other cases they seem to be especially resistant or young forms, essential for the preservation and perhaps propagation of the microorganism of leprosy. Obviously, the importance of these forms for scientific study and practical work in leprosy cannot be overestimated...