Measurement of acute phase proteins for assessing severity of Plasmodium falciparum malaria

Seventeen adult patients with acute Plasmodium falciparum malaria, admitted to the Hospital for Tropical Diseases, were studied. Serial measurements of the serum concentration of C-reactive protein, serum amyloid A protein, and percentage parasitaemia were determined, together with initial measurement of serum electrolytes, liver function, haemoglobin, white cell and platelet counts. Initial C-reactive protein and serum amyloid A concentrations were increased (C-reactive protein mean 49.0 mg/l serum amyloid A 28 mg/l) falling towards the normal range by the seventh day of treatment. There was a significant correlation between the pretreatment parasite count and clinical and laboratory markers of inflammation. C-reactive protein and serum amyloid A concentrations correlated inversely with the serum sodium. These results indicate that measurement of acute phase reactants such as C-reactive protein and serum amyloid A may prove valuable in assessing the severity of P falciparum malaria, and in following the response to antimalarial treatment.

The primary antibody response of malaria patients to Plasmodium falciparum sexual stage antigens which are potential transmission blocking vaccine candidates

Thirty serum samples collected from adult patients attending the Hospital for Tropical Diseases, London, with P. falciparum malaria, were studied. Sera were screened by indirect immunofluorescence for anti-gametocyte antibodies. Twelve of the serum samples taken from 14 patients with primary infections were found to have both IgM and IgG antibodies to gametocyte antigens and total Ig titres comparable with those of patients who had had previous malaria attacks. Sera of individuals from hyperendemic areas have been found to immunoprecipitate the 230 and 48/45 kD gametocyte surface antigens which are known targets of transmission blocking antibodies. To investigate the epitope specificity of the serum samples from our adult patients, competitive ELISAs with 3 monoclonal antibodies (MAbs) that block transmission and recognize different epitopes on the 48/45 Kd antigen, were carried out. Specific antibodies for these epitopes were found in 60% of the sera while nearly a third were able to inhibit the binding of at least two MAbs.

Human gnathostomiasis

Following a meal that included raw fish in Bangladesh, a woman aged 40 years had symptoms suggestive of gnathostomiasis. The presentation of her illness and the results of investigations are reported.

Studies on immunisation of pigs with the Bartha strain of Aujeszky's disease virus

The K strain of Aujeszky's disease virus (ADV) grown in Vero cells was used to vaccinate pigs. Following intramuscular inoculation, the pigs remained healthy, no vaccine virus was excreted and virus could be detected only at the inoculation site. One inoculation gave good protection against challenge with a virulent strain of ADV, and the amount of virulent ADV excreted was geatly curtailed. Following vaccination only low leads of serum neutralizing antibody were detected (geometric mean titre 1/2), but three weeks after challenge very high levels were found (GMT 1/1773). Intranasal vaccination gave similar results. There was minimal excretion of vaccine virus. The clinical reaction on challenge was less severe than in the intramuscularly challenged group, although lower antibody levels were detected three wekks following challenge (GMT 1/483). A field trial, using this strain given subcutaneously, indicated that one inoculation of this vaccine is effective.

Further studies on experimental bacterial pneumonia: ultrastructural changes produced in the lungs by Salmonella cholerae-suis

The development of ultrastructural changes in the lungs of pigs was examined at intervals from 6 hours to 14 days after intranasal infection with virulent Salm. cholerae-suis. Most bacteria were phagocytosed by PMN and pulmonary macrophages immediately after arrival in distal airways and alveoli. During the first few days after infection oedema fluid formed in interalveolar septa and alveoli, there was exudation of fibrin and degenerative changes of a mild nature occurred in epithelial cells. Bacteria laden phagocytic cells migrated through the tissues to pulmonary lymphatics and capillaries. Many bacteria survived and multiplied in phagocytes, causing necrosis of the cells from the fifth to the seventh day, when large numbers of organisms were liberated into the tissues. This phase coincided with widespread exudation and maximum destruction of lung tissue. Although necrosis appeared to be caused by free organisms, at no stage did bacteria become attached to, or penetrate, pulmonary cells, and it is suggested that injury is mediated by a toxin produced by Salm. cholerae-suis. Many alveoli were distended by osmiophilic lamellar material released by degenerating type II pneumonocytes. This appearance and later hyperplasia of type II epithelial cells and excessive secretion of lamellar bodies was typical of the changes in human alveolar lipoproteinosis. From the ninth day onwards the number of bacteria in the lung fell dramatically, organisms were confined to circumscribed abscesses and lymphoid tissue developed throughout the lungs.

Ultrastructure of phagocytosis of Salmonella cholerae-suis by pulmonary macrophages in vivo

Phagocytosis of virulent Salmonella cholerae-suis in the lungs of pigs was studied by electron microscopy during the period 6 hours-14 days after intranasal infection. All bacteria were phagocytosed by polymorphonuclear leucocytes (PMN) and pulmonary macrophages soon after arrival in distal airways and alveoli. Many organisms were destroyed but some survived and later multiplied within phagocytes. Bacteria were also carried in phagocytic cells to lymphatics and pulmonary capillaries, thereby establishing bacteraemia. Between the 5th and 7th days bacteria caused necrosis of the phagocytes and were released into the tissues in very large numbers. Destruction of all types of lung cell was widespread during this period but the Salmonellae did not penetrate pulmonary cells. From the 9th day onwards bacteria in the lung were restricted to circumscribed abscesses and lymphoid tissue developed throughout the lungs. These latter changes coincided with the appearance of circulating specific antibody.

The histopathology of Fasciola hepatica infections in sheep

Experimental infections of lambs with Fasciola hepatica are described. The growth rate of the parasite, time of entry to the bile ducts, and time of patency are recorded and a preferential migration of the parasite in the liver parenchyma noted. The gross and histological lesions produced in the liver from 1 to 40 weeks after infection are described and compared with previous observations in cattle.

The parenchymal migration of the parasite is shown to consist of two phases, a free migrating phase up to the 6th week, and a localized phase after the 6th week prior to entry into the bile ducts. Hepatic cell regeneration is observed and hepatic fibrosis is minimal. The localized phase of migration is associated with a unique peripheral palisade of giant cells in the fluke tracts and with the formation of pseudofollicular aggregation of lymphocytes. The presence of flukes in the bile ducts produces fibrosis of the duct walls. The walls, however, remain pliable and expanded to accommodate the parasites and calcification was never observed.