Detection of circulating parasite antigen and specific antibody in Toxocara canis infections

Serological surveys, measuring humoral antibody responses, have indicated significant levels of human infection with the zoonotic nematode Toxocara canis, and raised concern about the resultant risk of ocular and neurological damage. Such measurements do not distinguish with certainty current infection from past exposure. Thus, we have developed a test for circulating Toxocara antigen released by parasites in the host. This monoclonal antibody-based two-site 'sandwich' assay discriminates between T. canis and the related feline ascarid T. cati, and has been used, in tandem with the standard ELISA, to examine experimental and human infections. In experimental animals, antigen is transiently detectable, disappearing when immunocomplexed with host antibody. Antigen was also found in sera from UK patients diagnosed with visceral or ocular toxocariasis, and in four asymptomatic Papua New Guinean children. In the latter population, individuals positive for parasite antigens were not necessarily positive for antibody, implying that some infected cases may be negative in the current diagnostic ELISA. The antibody test was also adapted to measure host antibody directed to single monoclonal antibody-defined epitopes, revealing evidence of differential temporal regulation of distinct antibody specificities.

Meningitis in an Irish community

A series of 26 cases of meningitis occurring in one year in a defined area is presented. The clinical features, and complications are reviewed. Neisseria meningitidis occurred twice as commonly as Haemophilus influenzae, suggesting that the pattern of infection differs from that reported in England and Wales. An incidence of 4.6/100,000 for N. meningitidis is reported exceeding rates of infection in previous UK "epidemics".

Toxocariasis: a practical approach to management of ocular disease

The diagnosis of ocular toxocariasis is difficult to make with certainty. New methods of antigen detection are helpful. Surgical intervention may play a role in improving the prognosis, but the place of specific chemotherapy remains undefined. We discuss three case histories to illustrate these points. We suggest that the visual prognosis need not be so poor as commonly believed, and outline a suggested plan of management.

The epidemiology of Toxocara canis

Bred as hunter, companion and pet, the dog has a long and honourable association with man. Yet the domestic dog can host a wide range of parasites - many of which can also infect humans. One of these, the ascarid nematode Toxocara canis (Fig. 1), is of particular interest because of retinal damage that may result from larvae becoming trapped in the eye. At the Hospital for Tropical Diseases in London, about 20-30 patients with toxocariasis are treated annually. Widespread fouling of public parks, playgrounds and pedestrian areas with dog faeces - especially in large cities - is well -recognized as one of the main sources of Toxocara infection. Yet as Stephen Gillespie discusses here, epidemiological indicators vary widely and the risk of infection is often treated too lightly.

Rapid diagnosis of whooping cough using monoclonal antibody

A counterimmunoelectrophoresis (CIE) method for antigen detection using monoclonal antibody was assessed for its ability to aid in the rapid diagnosis of Bordetella pertussis in 59 patients. A positive diagnosis from a combination of results from tests of serum and urine was obtained in 51 (87%) of cases. For sera, CIE had a sensitivity of 85% and a specificity of 94%; for urine samples the sensitivity was 81% and a specificity of 100%. Antigen detection by CIE is simple to perform and yields results on the same day, thus allowing treatment to begin at an early stage.

Susceptibility of Pseudomonas pseudomallei to new beta-lactam and aminoglycoside antibiotics

Pseudomonas pseudomallei is resistant to many antimicrobial agents. We determined the susceptibility to twelve beta-lactams and six aminoglycosides of twelve isolates of P. pseudomallei. Imipenem (MIC range 0.5-1.0 mg/l; MIC90 1.0 mg/l), ceftazidime (MIC range 1-8 mg/l; MIC90 8.0 mg/l), amoxycillin/clavulanate (MIC range 4-8 mg/l; MIC90 8.0 mg/l), piperacillin (MIC range 4-16 mg/l; MIC90 8.0 mg/l), and carumonam (MIC range 4-16 mg/l; MIC90 8.0 mg/l) were the most active. Aminoglycosides were relatively inactive, for example, gentamicin (MIC range 16-64 mg/l; MIC90 64 mg/l), netilmicin (MIC range 16-128 mg/l; MIC90 128 mg/l) and amikacin (MIC range 32-64 mg/l; MIC90 64 mg/l).

Malaria in Northern Ireland

The clinical features, parasitology and prophylactic history of 67 patients who imported malaria to Northern Ireland between 1974 and 1983 are reported. P. falciparum infections were encountered more frequently than anticipated from current United Kingdom experience. The clinical implications of these findings are discussed.