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A report of acute corneal changes in workers employed in the chloroquine industry is presented. The workers were exposed to chloroquine phosphate dust in the manufacture of chloroquine tablets, and the corneal alterations were similar to those described after long continued systemic chloroquine therapy.

The present study shows that oral inoculation with infective A. suum eggs or 3rd stage larvae in pigs aged 5-16 weeks induces resistance against oral challenge with infective A. suum eggs. Acquired resistance is reflected by an adaptive type of host response as measured by increased pathological, serological and hematological responses and decreased recovery of worms from lungs and small intestine. Although based on a limited number of experimental pigs, the results of the present experiments suggest that resistance to A. suum may be induced both when the parasites are introduced directly into the digestive tract as 3rd stage larvae, i.e. without a previous migration through the liver and lungs, and when given as infective eggs.

An increasing number of young people in the Nordic countries try to commit suicide. Some of these attempts could perhaps be prevented if there was widespread knowledge of several characteristic features of such youngsters, and if we sought to give them attention and assistance.

The mouse has been shown to be a suitable experimental host in studies of the resistance to Fasciola hepatica infection. The present experiment compares the course of infection in two different strains of mice, including immunodeficient (congenitally athymic (nude)--(nu/nu)) mice. It was found that the infection was lethal in nu/nu mice, whereas nu/nu mice reconstituted with a neonatal thymus graft reacted as intact mice. The white blood cell picture of nu/nu mice remained unchanged during the infection and between day 24 and 30 after inoculation nearly all nu/nu mice died. Thymus-bearing mice showed blood leucocyte increase and neutrophilia from week 3 after primary inoculation. Furthermore, a marked peritoneal cell reaction occurred 2--4 weeks after primary inoculation. The total number of cells in peritoneal cavity increased approx. 10--15 times and a very remarkable eosinophil peak was seen in week 3 after primary inoculation. In nu/nu mice the peritoneal cell increase was approx. twice that of uninoculated mice and no eosinophil response was observed. When results obtained with the various groups of mice are compared, it appears that resistance to F. hepatica during infection is dependent on a functional thymus.

We studied whether gut mucosal IgA antitoxin production as well as the acquired protection against cholera toxin (CT) after oral immunization with CT are both thymus-dependent immune manifestations. In contrast to normal BALB/c mice, nude, athymic mice did not respond to oral immunizations with CT with either IgA antitoxin-producing cells (SFC) in the lamina propria or protection against challenge with CT in ligated intestinal loops. However, when nude mice were first reconstituted by grafting of syngeneic thymus glands, both IgA antitoxin SFC in the lamina propria and protection were stimulated by oral immunizations with CT and the response were of similar magnitude to those of normal mice after immunizations. During in vitro culture, isolated lamina propria lymphocytes from immunized but not from control mice concomitantly and proportionally produced IgA antitoxin and CT-neutralizing activity. We conclude that intestinal antitoxin formation and protection against toxin challenge after oral immunization with CT are both critically thymus-dependent and therefore likely to be under T-cell control.