toman's tuberculosis case detection, treatment and monitoring

TOMAN’S TUBERCULOSIS
Table 5
Frequency of agreement or disagreement between four microscopists on the score
of positive results (data from Table 4 presented in percentages)
All other microscopists Total (%)
Negative Scanty 1+ 2+ 3+
Report of one 1+ 19 5 25 42 9 100
microscopist 2+ 2 7 14 34 43 100
3+ 0 2 2 28 68 100
the frequency of agreement between equally proficient microscopists may reach
93%. However, these results were achieved under experimental conditions and with
experienced laboratory technicians. The question that arises is, “How does smear
microscopy work under field conditions, particularly in peripheral health centres of
developing countries?” This question is answered below.
Smear microscopy under field conditions in developing countries
In peripheral health centres, sputum collection, the preparation and staining of
smears, and their examination by microscopy are usually performed under suboptimal
conditions – often by microscopists with limited experience. This applies to most
of the peripheral health centres in rural areas, which are attended by the majority of
patients complaining of chest symptoms. As a rule, such patients are offered a sputum
examination for diagnosis. The standard of case detection in developing countries
therefore depends, in addition to operational factors, largely on the technical performance
of smear microscopy.
In order to assess the qualitative performance of sputum examination in rural
health institutions, several studies were carried out by the National Tuberculosis Institute,
Bangalore, India (4, 5). In a South Indian district where a district tuberculosis
programme had been implemented about 6 months before the investigation, the performance
of nine randomly selected health centres was analysed. The microscopists
at these centres were non-specialized health workers who had been trained for 2–4
weeks in the collection and examination of sputum according to a manual that they
had been given. They had received on-the-job training from an experienced laboratory
technician, who was also a member of the tuberculosis control team (6, 7). The
team was responsible for the implementation and supervision of the programme in
the entire district (population 1.5 million).
Method of assessment
In each of the nine centres, one sputum sample was collected from every patient complaining
of persistent cough and a smear was prepared and examined immediately
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