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Biomedical subjects

A C McDougall

Publications and source records attributed to A C McDougall.

At least 19 recordsLinked to original sources
PubMed1992

The allocation of leprosy patients into paucibacillary and multibacillary groups for multidrug therapy, taking into account the number of body areas affected by skin, or skin and nerve lesions.

In Nepal, the setting up and maintaining of reliable services for slit-skin smears has proven difficult. A clinical classification system for leprosy has therefore been developed to assist in the allocation of patients to either paucibacillary or multibacillary groups for the purpose of multiple drug therapy (MDT), using 9 body areas: head (1), arms (2), legs (2), trunk (4). Patients with more than two areas of the body affected are grouped as multibacillary (MB) and those with only one or two areas affected are paucibacillary (PB). Using a computer simulation model and the data of 53 patients registered at Green Pastures Hospital (GPH) in Pokhara and 703 field patients from the Western Region, different clinical classification systems were evaluated with regard to their sensitivity, specificity, and predictive value for MB or PB classification, as compared with the histological classification for the GPH cases and the bacteriological classification for the field patients. The sensitivity and specificity of the body area system in present use were 93% and 39%, respectively. The low specificity is due to MB overclassification. The sensitivity of the WHO classification system without skin smear facilities is 73% (the difference with the body area system is significant: p < 0.05, McNemar's test). Our histology findings confirm previous publications indicating that, while some borderline-tuberculoid (BT) patients may outwardly have a 'PB appearance' and be skin-smear negative, their nerve biopsy and sometimes skin biopsy may show a 'MB' picture. This is the first publication discussing a 'body area system' for the purpose described, including diagrams of the areas used. In Nepal it has proved easy to use and teach and its use may be justified in other control programmes which implement MDT, particularly if slit-skin smear services are unreliable or nonexistent.

Adolescent↗
PubMed1991

ALERT-India 1981-89: nine years' experience of leprosy control in the slums of Bombay.

Bombay has a population of about 8 million people, one-half of whom live in slums. In 1981, ALERT-India started its first leprosy control project in N, S and T Wards of Greater Bombay Municipal Corporation covering an area of 122 sq km in the north-eastern suburbs of Vidhyavihar, Ghatkopar, Vikhroli, Kanjurmarg, Bhandup and Mulund, with a total population of 1,100,000 according to the 1981 census. In the 9 years of operation, over 12,000 patients have been registered and treated and of these 7425 have been released from treatment, having satisfactorily completed courses of chemotherapy. However, over 1000 cases are still identified every year by house-to-house or school surveys, or by self-reporting, including a considerable percentage in children. The origin, development, staff structure, operational procedure, administration and recording system of ALERT-India are described in detail, with emphasis on what has been accomplished with purely outpatient facilities, using paramedical workers, all of whom have received inservice training from Government recognized training centres for their specific tasks. The account includes a brief description of an expansion of the organization's work into townships in New Bombay, where preliminary surveys in 1988 confirmed the presence of leprosy cases and the need for treatment facilities. The discussion addresses: 1, the better use of the large volume of statistical information which has been collected by ALERT-India during the past 9 years, with emphasis on its value in assessing the impact on the control programme and modifying future policy; 2, the need to radically examine the present policy of survey, versus an 'education campaign approach' with regard to increasing early case-detection and self-reporting; 3, the establishment of a central coordinating body for leprosy control in Bombay to exchange information, coordinate efforts and formulate a future plan of action, the latter in association with the National Leprosy Eradication Programme; and 4, the development of a health education resource centre in association with the Bombay Municipal Corporation.

Health Services↗
PubMed1990

A re-appraisal of clinical and bacteriological criteria in the implementation of multiple drug therapy for leprosy control programmes and proposals for their better use.

Behind the appraisal of criteria above and our proposals, is the question 'To what extent and for what purpose should slit-skin smears be used in programmes implementing MDT?' The answer may lie somewhere between the extreme of abolishing them altogether and the present situation, in which many people seem to think that a comprehensive service has to be provided at many levels, including the periphery, almost regardless of quality and with minimal supervision. Our plea is twofold: (1) the much wider use of standardized clinical, as opposed to bacteriological, criteria for the grouping of the patients, the termination of treatment in multibacillary cases and follow up, and (2) the abolition of the routine use of slit-skin smear examination in the field, coupled with the phasing out of unsupervised peripheral units of doubtful quality and the identification of one laboratory at central or provincial level which is able to provide a reliable, high quality service for smears in selected cases. Clearly these proposals will not solve all the operational and methodological problems. There is an urgent need for research on the best ways to implement MDT on a large scale. But the truth of the matter is that 7 years after the WHO recommendations and for reasons which have so far been poorly defined, less than half the world's registered cases have so far received MDT. Most of the registered cases continue to take a form of treatment, dapsone monotherapy, which was condemned over 10 years ago as being hazardous on account of the dangers of resistance.(ABSTRACT TRUNCATED AT 250 WORDS)

Drug Therapy, Combination↗
PubMed1990

Mode of transmission and histology of M. leprae infection in nude mice.

Athymic (nude) mice were experimentally infected with Mycobacterium leprae via the alimentary and respiratory tracts and through the skin. Animals were allowed to inhale aerosols of M. leprae or had bacilli instilled into the nostrils or directly into the lungs. Others were fed M. leprae by gastric tube or had bacilli placed on the tongue. Attempts were also made to transmit M. leprae from infected footpads by Aedes aegyptii mosquitoes. The most successful infections resulted from nasal instillations and from bacilli inoculated onto the tongue surface: in these cases heavy systemic infections occurred. M. leprae was also shown to survive passage through the alimentary tract and bacilli recovered from the faeces were capable of causing infection in recipient nude mice. The possible epidemiological significance of these findings for the transmission of leprosy in man is discussed.

Animals↗
PubMed1979

Dapsone.

Explore the source record for details and available documents.

Dapsone↗
PubMed1979

The paranasal sinuses in lepromatous leprosy.

During the course of a larger study of patients with treated lepromatous leprosy attending a hospital in South India, sixteen patients with untreated disease presented with symptoms suggesting both intranasal and sinus involvement. Radiological abnormalities of the sinus were recorded in all sixteen patients and the results have been published separately. This paper describes the clinical and bacteriological findings, together with the results of histopathological examination of biopsies of sinus mucosa in two patients, in both of whom there was a histiocytic infiltrate, with acid-fast bacilli. In one of these biopsies, bacilli in the lamina propria were numerous; globi were common, and 20% of free-standing organisms were solid-staining. The significance of these findings is discussed with emphasis on the value of a full ear, nose and throat examination in all cases of leprosy, especially those with the lepromatous form. In this type of leprosy the upper respiratory tract tissues are clearly of importance for the lodgement and of multiplication of bacilli; it is possible that the paranasal air sinuses, with their large surface area, may contribute to the numbers of bacilli which are disseminated from the nose into the environment.

Body Temperature↗
PubMed1979

Untreated lepromatous leprosy: histopathological findings in cutaneous blood vessels.

Skin biopsies from 100 patients with untreated lepromatous leprosy from Malaysia, India, Africa, and South America were examined with particular regard to pathological changes in intima, media, or adventitia of blood vessels and to the presence of leprosy bacilli in these layers. Bacilli were found in capillaries, venules, or arterioles in all cases, and in many instances they were present in endothelial lining cells or smooth muscle in large masses (globi). In several cases, solid-staining bacilli in endothelial lining cells were especially prominent. The findings are discussed in relation to a) the continuous bacteremia of lepromatous leprosy, b) the role of endothelial cells in phagocytosis, c) smooth muscle cells of the media as a site in which bacilli may persist, and d) the transmission of human leprosy by biting arthropods.

Blood Vessels↗
PubMed1978

Ocular histopathology in animals experimentally infected with Mycobacterium leprae and M. lepraemurium. 1. Mycobacterium leprae and M. lepraemurium infections in the mouse. 2. Mycobacterium leprae infections in the 9-banded armadillo (Dasypus novemcinctus L.).

At varying periods of time following the successful establishment of systemic infections with Mycobacterium leprae or M. lepraemurium in the mouse and the nine-banded armadillo eyes were examined by light microscopy. Inoculation of bacilli was by the intravenous or intraperitoneal route or directly into the hind footpads; eyes were not directly inoculated in this study. During periods of up to 3 years under laboratory conditions no animal showed evidence of impaired vision or blindness, and the external appearance of both eyes was normal. The ocular histopathology and the sites of accumulation of bacilli are described. In immunologically normal mice infected with M. lepraemurium bacilli were much commoner in extraorbital tissues, but they were, nevertheless, found in various tissues within the orbit, including the ciliary body and sclera. In immunologically normal mice (and one rat) injected with M. leprae of human origin no bacilli were found in the eye, but in mice immunologically depressed by thymectomy and total body irradiation considerable numbers of bacilli were present in the iris and ciliary body and also in the limbal cornea. In the armadillo bacilli were found in large numbers in virtually all tissues except the lens, retina, optic nerve, and aqueous and vitreous humours, but the uveal tract was heavily involved. Findings are discussed in relation to the great frequency of ocular involvement and the importance of immune-complex disease in patients with lepromatous leprosy, and to factors wihch may favour the localisation and multiplication of Mycobacterium leprae in the eye.

Animals↗
PubMed1978

Peripheral nerve biopsies in the diagnosis of leprosy in Aboriginal patients from the Northern Territory of Australia.

In the 12 years from 1964 to 1976, 171 peripheral nerve biopsies were taken from 81 Aboriginal patients in the Northern Territory of Australia, in whom a diagnosis of leprosy was either known or strongly suspected. Sixty-eight biopsy samples were from 19 patients known to have leprosy, and who were under assessment for nerve grafting, results of which have already been published. We describe here the histopathological findings in the remaining 62 patients, in whom a diagnosis of leprosy was suspected on clinical grounds, backed in many cases by abnormalities of nerve conduction. Forty-one patients (66%) had abnormal histopathological findings in the nerve biopsy sample, 19 (31%) showing definite evidence of leprosy. Several patients with enlarged peripheral nerves, in whom the biopsy findings did not confine leprosy, remain under observation; their future investigation will include lymphocyte transformation tests and testing with refined lepromin, together with repeat nerve biopsy, where ethical and feasible. The clinical and epidemiological data suggest that a previous, and perhaps self-healing, form of leprosy may account for the neurological findings.

Abscess↗