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A microscope at the grassroots

Jan Swasthya Sahyog’s experiences in a small hospital with an active village outreach programme show that the cost, versatility, sensitivity and specificity of the microscope make it the most important investment for a small healthcare unit. Biswaroop Chatterjee explains

According to Monica Cheesbrough, an authority on medical laboratory practice in tropical countries, microscopy forms 70-90% of the diagnostic work at the community health centre level. A laboratory at this level can increase the accuracy of diagnosis and thereby curtail expenditure by reducing the need for ‘shotgun’ therapy. It can also assess response to therapy, screen for diseases, and investigate epidemics (1). Some of India’s most important public health problems, such as tuberculosis (2) (estimated burden of 3.8 million patients shedding bacilli in their sputum in 2000), malaria (3) (reported burden of 1.7 million patients in 2003), and cancer of the uterine cervix (4) (estimated burden of 0.11 million new patients in 2004) can be diagnosed or screened with the help of a microscope.

From our experience in a small hospital with an active village outreach programme, we feel that a microscope is the most cost-effective investment that a small healthcare unit can make. We use the microscope every day to investigate the following symptoms that many of our patients complain of:

Cough with or without fever

Ziehl-Neelsen-stained sputum smears are used for acid-fast bacilli, for the presumptive diagnosis of tuberculosis. In the early years of our hospital, when we did not have an x-ray machine and had to depend entirely on microscopy to diagnose pulmonary tuberculosis, we resorted to concentrating sputum samples with a solution containing 1% sodium hydroxide and 3% ammonium sulphate (5). This increased our sputum-positivity rates by 89% in a series of 1,966 patients.

Gram-stained sputum smears are used for patients with productive cough and fever. Streptococcus pneumoniae, the most common cause of severe, community-acquired pneumonia worldwide, has a characteristic microscopic picture, with numerous pus cells and abundant encapsulated Gram-positive cocci in pairs (6).

Absolute eosinophil count is used for patients with tropical pulmonary eosinophilia and Löffler’s Syndrome (7). Laboratories in northeastern India could also look for Paragonimus ova in sputum from patients complaining of cough and bloody sputum (7).

Diarrhoea

We use saline mounts of stool for pus cells, which indicate the need for antibiotics; saline and iodine mounts of stool for parasites and their ova and cysts (7); hanging drop preparation of stool for Vibrio cholerae (8); and Modified Kinyoun-stained stool smears for oöcysts of Cryptosporidium and Isospora (7).

There have been several instances at our centre when the detection of Isospora in patients with long-standing diarrhoea and severe weight loss has led to the diagnosis of HIV infection. These patients have subsequently been cured of their diarrhoea with a course of Co-trimoxazole worth Rs 25.

Fever without localised symptoms

We do peripheral blood smears for malaria parasites (7). Our village health workers use bus conductors to send blood smears to our health centre for same-day reporting -- a system that has served more than 9,000 patients so far with average slide positivity rates of around 20%.

We also do total and differential leukocyte counts in blood; microscopic examination of urine sediment for pus cells and bacteria; slit-skin smears for acid-fast bacilli. Multi-bacillary leprosy is common enough in our area for type II reactions to be a significant cause of ‘fever of unknown origin’. Some of these patients lack discrete skin lesions and can be diagnosed only with the help of a microscope (9).

Laboratories in Bihar, West Bengal and Assam could also look for L-D bodies in splenic or bone marrow aspirates to diagnose kala-azar.

Joint pain and/or swelling (10)

We use total and differential cell count of synovial fluid and Gram-stained smear of synovial fluid for bacteria.

Dysuria (burning sensation while passing urine)

We use a wet mount of urinary sediment for pus cells and Trichomonas vaginalis (7) and Gram-stained urethral smear for pus cells containing Gram-negative diplococci, a finding that is highly specific for gonorrhoea in male patients (11).

Excessive vaginal discharge

We take a saline mount of vaginal fluid for Trichomonas vaginalis (7).  And a Gram-stained smear of vaginal fluid to look for clue cells and bacterial morphological types for bacterial vaginosis (12); pus cells trapped in cervical mucus for endocervicitis (13); and yeast cells with pseudohyphae for Candida vaginitis.

More than half our patients are diagnosed with bacterial vaginosis and they go home with Rs 14 worth of metronidazole as the only treatment. If these women were to be given syndromic treatment for vaginal discharge, without a specific diagnosis, it would cost them Rs 50 for metronidazole, doxycycline, and fluconazole. In addition, they would be exposed to the risk of side-effects from medicines that many of them would not have needed.

Anaemia

Romanowsky-stained thin blood films for microcytic and hypochromic red cells as well as pencil-shaped, teardrop-shaped and target-shaped red cells in iron-deficiency anaemia; macrocytic red cells and hyper-segmented polymorphs in folic acid or Vitamin B12-deficiency anaemia; and extreme aniso-poikilocytosis in thalassaemia.

Sodium dithionite mounts for sickle-cell anaemia.

Infertility

Semen analysis. We always do this test before embarking on more invasive and expensive investigations on the woman.

Our laboratory is staffed completely by locally trained technologists who belong to the area, contradicting the misconception that it is difficult to train and retain dependable microscopists in the ‘periphery’. Several of our technologists can perform all the tests mentioned above. They also function as trainers.

Microscopy vs disease-specific kits

Cost: A good Indian binocular microscope, inclusive of a voltage stabiliser, costs Rs 25,000 ($500) and provides the same resolution as competing brands abroad. Assuming a working life of just three years, under conditions of rough handling in high temperatures and humidity, the depreciation of the microscope will be Rs 28 per working day, or Re 0.56 per test, if 50 microscopic tests are done every day for 300 days a year. If one adds the cost of electricity, immersion oil, microscope slides, cover glasses, stains, lens tissue, and even the occasional replacement of microscope bulbs, the material cost comes to approximately Rs 9 per test. If one adds the salary of a technologist, at Rs 15,000 per month, ie, Rs 20 per test, the net cost of one microscopic test comes to Rs 29 (59 cents).

Few kit-based tests can be offered at these prices if one includes the salary of the technologist using the kit and the cost of transporting and storing kits under cold chain. Even though many modern kits are stable at environmental temperatures prevailing in temperate countries (up to 35°C), this ‘room temperature’ is exceeded in summer in many parts of India, especially in trucks and badly ventilated storage depots. Cooling in some form is therefore essential for the assured performance of these kits, and this should be factored in while comparing the costs of microscopy with disease-specific kits. A variable proportion of kits in stock often cross the expiry date and are wasted, leading to increased costs.

Versatility: Most diagnostic kits focus on just one parameter or analyte, such as malaria antigen, at a significant cost. A microscope does quite the opposite: it is a versatile instrument that helps diagnose dozens of illnesses. It can provide unexpected clues to the diagnosis, whereas disease-specific kits can only confirm what is suspected. For example, a technologist in our laboratory once diagnosed sickle-cell anaemia when he noticed sickle-shaped red blood cells in a sample of urine and then ran a haemoglobin electrophoresis on a blood sample to prove the diagnosis!

Specificity and sensitivity: If good-quality consumables are used and correct techniques followed, there is little doubt about what is seen under a well-maintained microscope by an experienced technologist; after all ‘seeing is believing’. The specificity of microscopy for malaria diagnosis was found to be 100% when compared against PCR in a series of 124 febrile cases in Iran, in 2002 (14). This cannot be said about many disease-specific diagnostic kits whose performance depends on intrinsic design, standards of manufacture, and conditions of storage. In a study done by us on 192 patients with fever, in 2008, we found that the top-selling malaria rapid diagnostic kit in our district had a sensitivity of 73% and specificity of 92%, when compared with microscopy of thick films.

The microscope as ‘self-help’ technology

A survey done in 2001 by the New Delhi Tuberculosis Centre found that 67% of chest symptomatic patients attending the out-patient clinic had already had a chest x-ray done, but not sputum microscopy. Most of the x-rays were advised by doctors in private practice and in government hospitals (15).

The Revised National Tuberculosis Control Programme (RNTCP) has provided a much needed boost to microscopy in rural areas. The programme, first launched in 1993, has set up microscopy centres (MCs) for every 100,000 population across the country (16). These microscopy centres have proved the feasibility of providing high-quality microscopy services in rural areas. However, the centres should be gradually integrated into the horizontal health system, not only to tap their immense diagnostic potential for other diseases but also to prevent ‘work expanding so as to fill the time available for its completion’, since only “2-3% of new adult out-patients in any general health facility will have a cough for three weeks or more” (17).

To quote E F Schumacher: “As Gandhi said, the poor of the world cannot be helped by mass production but by production by the masses… The system of production by the masses mobilises the priceless resources which are possessed by all human beings, their clever brains and skilful hands, and supports them with first-class tools.” A good microscope in the hands of a competent technologist is a perfect example of such a tool, a tool that can help us reach the Alma-Ata goal of “…essential healthcare based on practical, scientifically sound and socially acceptable methods and technology made universally accessible to individuals and families in the community through their full participation and at a cost that the community and country can afford to maintain at every stage of their development in the spirit of self-reliance and self-determination” (18).

(Biswaroop Chatterjee is a consultant microbiologist with a hospital in Howrah, West Bengal)

References

1 Cheesbrough M. ‘District Laboratory Practice in Tropical Countries’. Part 1. Cambridge: Cambridge University Press; 1998
2 Tuberculosis Research Centre, Chennai. ‘Burden of Tuberculosis in India for the Year 2000’. In: NCMH Background Papers -- Burden of Disease in India. New Delhi, India. National Commission on Macroeconomics and Health, Ministry of Health and Family Welfare, Government of India. 2005. p 24-5
3 Dua A S. ‘Programmes for the Control of Leprosy, Tuberculosis and Malaria’. In: NCMH Background Papers -- Burden of Disease in India. New Delhi, India. National Commission on Macroeconomics and Health, Ministry of Health and Family Welfare, Government of India. 2005. p 9-23
4 Nair M K, Varghese C, Swaminathan R. ‘Cancer: Current Scenario, Intervention Strategies and Projections for 2015’.  In: NCMH Background Papers -- Burden of Disease in India. New Delhi, India. National Commission on Macroeconomics and Health, Ministry of Health and Family Welfare, Government of India. 2005. p 219-25
5 Vasanthakumari R. ‘Concentrated Sputum Smear Microscopy: A Simple Approach to Better Case Detection in Pulmonary Tuberculosis’. Indian J Tub 1988; 35:80-2
6 Donowitz G R, Mandell G L. ‘Acute Pneumonia’. In: Mandell G L, Bennett J E, Dolin R, editors. Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases. 6th ed. Orlando: Churchill Livingstone; 2005. p 820-45
7 Sun T. Parasitic Disorders: Pathology, Diagnosis and Management. 2nd ed. Baltimore: Williams and Wilkins; 1999
8 Seas C, Gotuzzo E. Vibrio cholerae. In: Mandell G L, Bennett J E, Dolin R, editors. Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases. 6th ed. Orlando: Churchill Livingstone; 2005. p 2536-44
9 Levis W R, Ernst J D. Mycobacterium leprae (Leprosy, Hansen’s Disease). In: Mandell G L, Bennett J E, Dolin R, editors. Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases. 6th ed. Orlando: Churchill Livingstone; 2005. p 2886-96
10 Cush J J, Lipsky P E. ‘Approach to Articular and Musculoskeletal Disorders’. In: Fauci A S, Braunwald E, Isselbacher K J, Wilson J D, Martin J B, Kasper D L et al (eds). Harrison’s Principles of Internal Medicine. 14th ed. New York: McGraw-Hill: 1928-35
11 Baron E J, Peterson L R, Finegold S M, editors. Bailey and Scott’s Diagnostic Microbiology. 9th ed. St Louis: Mosby; 1994
12 Nugent R P, Krohn M A, Hillier S L. ‘Reliability of Diagnosing Bacterial Vaginosis is Improved by a Standardised Method of Gram Stain Interpretation’. J Clin Microbiol 1991; 29:297-301
13 Holmes K K, Handsfield H H. ‘Sexually Transmitted Diseases: Overview and Clinical Approach’. In: Fauci A S, Braunwald E, Isselbacher K J, Wilson J D, Martin J B, Kasper D L et al (eds). Harrison’s Principles of Internal Medicine. 14th ed. New York: McGraw-Hill: 801-12
14 Haghdoost A-A, Mazhari S, Bahadini K. ‘Comparing the Results of Light Microscopy with the Results of PCR Method in the Diagnosis of Plasmodium Vivax’. J Vect Borne Dis43, June 2006, pp 53-57
15 Dhingra V K, Rajpal S, Aggarwal J K, Chopra K K. ‘Dependence on Radiology for Diagnosing Pulmonary Tuberculosis: An Urban Situation’. Indian J Tub 2002; 49:153-6
16 Revised National Tuberculosis Control Programme. Central TB Division, Directorate General of Health Services. Technical and Operational Guidelines for Tuberculosis Control. New Delhi. Ministry of Health and Family Welfare, Government of India. 2005
17 Revised National Tuberculosis Control Programme. Central TB Division, Directorate General of Health Services. Managing the Revised National Tuberculosis Control Programme In Your Area -- A Training Course. Modules 1-4. New Delhi: Ministry of Health and Family Welfare, Government of India; 2005
18 World Health Organisation (homepage on the Internet). Geneva: Declaration of Alma-Ata. International Conference on Primary Health Care, Alma-Ata, USSR, September 6-12, 1978 (cited June 12, 2009). Available from: http://www.who.int/hpr/NPH/docs/declaration_almaata.pdf

Infochange News & Features, December 2010