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Biomedical subjects

C F Gilks

Publications and source records attributed to C F Gilks.

14 recordsLinked to original sources

The presentation and outcome of HIV-related disease in Nairobi.

The range of clinical presentations of HIV-related disease in Africa has not been adequately described, despite the fact that many hospitals have to rely heavily on clinical diagnosis. Six hundred adult medical patients seen in the Casualty Department of the main Government hospital in Nairobi were enrolled in a study of the presentation and outcome of HIV-related disease: 506 of these patients were admitted, of whom 19 per cent (95) were HIV seropositive. The remaining 94 were dealt with as outpatients: 11 percent (10) of these were seropositive. A history of prior treatment for sexually transmitted disease and, if male, being uncircumcised, were associated with being seropositive. Three presentations were strongly associated with HIV infection: acute fever with no focus except the gastrointestinal tract (enteric fever-like illness), acute cough with fever (community-acquired pneumonia) and chronic diarrhoea with wasting. The WHO clinical case definition (CCD) for AIDS missed a substantial amount of HIV-related morbidity (sensitivity 39 per cent) and misidentified many seronegative patients (positive predictive value 59 per cent). In comparison with the Centers for Disease Control surveillance definition for AIDS, the CCD was specific (91 per cent) and sensitive (79 per cent) but only had a positive predictive values of 30 per cent: the CCD may therefore be a poor surveillance tool for AIDS. Seropositive patients were much more likely to die than were seronegative patients (39 per cent vs. 15 per cent mortality). Enteric fever-like illness was the presentation which most commonly proved fatal. A wider spectrum of disease is associated with underlying HIV immunosuppression than has previously been described in Africa.

Acute Disease

Life-threatening bacteraemia in HIV-1 seropositive adults admitted to hospital in Nairobi, Kenya.

During 6 months, 506 consecutive adult emergency admissions to hospital in Nairobi were enrolled in a study of bacteraemia and HIV infection. 19% were HIV-1 antibody positive. Significantly more HIV-seropositive than seronegative patients had bacteraemia (26% vs 6%). The predominant organisms isolated from the seropositive patients were Salmonella typhimurium and Streptococcus pneumoniae. Mortality was higher in the seropositive than in the seronegative bacteraemic patients. The findings suggest that non-opportunistic bacteria are important causes of morbidity and mortality in HIV-infected individuals in Africa.

Acquired Immunodeficiency Syndrome

Extrapulmonary and disseminated tuberculosis in HIV-1-seropositive patients presenting to the acute medical services in Nairobi.

We studied 506 consecutive adult acute medical admissions to hospital in Nairobi; 95 (18.8%) were seropositive for HIV-1, and 43 new cases of active tuberculosis (TB) were identified. TB was clearly associated with HIV infection, occurring in 17.9% of seropositive patients compared with 6.3% of seronegatives [odds ratio (OR) 3.2; 95% confidence limits (CL) 1.6-6.5]. Extrapulmonary disease was more common in seropositive than seronegative TB patients (nine out of 17 versus five out of 26; OR 4.7; 95% CL 1.01-23.6); this accounted for most of the excess cases of TB seen in seropositive patients. Mycobacteraemia was demonstrated in two of eight seropositive TB patients but in none of 11 seronegative TB patients. No atypical mycobacteria were isolated. The World Health Organization (WHO) clinical case definition for African AIDS did not discriminate well between seropositive and seronegative TB cases. Five out of seven seropositive women with active tuberculosis had delivered children in the preceding 6 months and were lactating, compared with only one out of eight seronegative tuberculous women. An association between recent childbirth, HIV immunosuppression and the development of TB is suggested.

Adolescent

Relationships between sequestration, antigenic variation and chronic parasitism in Plasmodium chabaudi chabaudi--a rodent malaria model.

We describe here a rodent malaria model using cloned lines of Plasmodium chabaudi chabaudi in inbred CBA/Ca mice that exhibits both clonal antigenic variation in late stage-specific surface antigens, and deep vascular schizogony in the liver. We show that both these features are modulated by the spleen, and that surface antigen expression is crucially involved in the sequestering phenotype. Surface antigens are variant in chronic infection, and host protective immune responses can distinguish between these variants. Splenectomy abolishes this difference. The acute infection with non-sequestering cloned lines is kinetically indistinguishable from sequestering clones, but parasites unable to express variant sequestration-associated antigen do not form a chronic recrudescing infection. Another clone, able to re-express this antigen in the presence of the spleen, undergoes typical chronic recrudescence. In this model, the biological significance of sequestration-associated variant antigen seems to enable the establishment of chronic infection in the presence of a primed spleen.

Animals

Host diet in experimental rodent malaria: a variable which can compromise experimental design and interpretation.

Over the past few years several experienced groups studying malaria have encountered significant problems with their particular rodent malaria-host system. This has involved, in some cases, periods during which the recovery of cryopreserved parasite stocks and growth of bloodstream parasites was markedly inhibited and, in other cases, periods of drastically increased mortality rates. The common factor linking these incidents was that they coincided with alterations in the experimental animal diet used. The inhibition of growth of cryopreserved stabilates or bloodstream parasites was abolished by supplementation with p-aminobenzoic acid (PABA) or by changing the diet used. Although the suppressive effects of diets lacking PABA on parasite growth have been known for over 30 years, the variation of PABA levels in modern laboratory animal feed concentrates is not well recognized. We have not established the exact cause of increased mortality, but it has been overcome by changing the diet used. We are documenting our experiences with this potential variable to forewarn workers in other laboratories of possible problems inherent in the use of different diets.

4-Aminobenzoic Acid

Cycads and sago.

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Amino Acids, Diamino

Failure of penicillin prophylaxis in laboratory acquired leptospirosis.

A laboratory technician developed leptospirosis following accidental inoculation, despite prompt administration of parenteral penicillin by an accepted regimen of post-exposure prophylaxis. Another technician was similarly exposed and was given doxycycline; no illness or serological conversion followed. The implications of these cases are discussed and recommendations made for post-exposure chemoprophylaxis with doxycycline.

Accidents, Occupational

Strategies for the prevention of malaria in travellers: comparison of drug regimens by means of risk-benefit analysis.

A risk-benefit analysis has been used to balance the risks to travellers of death from malaria against the toxicity of various drug regimens. The mortality of travellers who take no prophylaxis is estimated to be surprisingly low, and it is concluded that most travellers, even in areas of drug resistance should take only non-toxic drugs, such as a combination of chloroquine and proguanil.

Africa