Newly diagnosed leprosy cases

Dear Sir,

The case report on ‘conjugal leprosy’ ¹ in a recent issue of Tropical Doctor raised some interesting issues. As many readers working in low prevalence areas may be unfamiliar with leprosy, I am taking the liberty of pointing out some aspects of the case not covered in detail by the author.

Since the consensus is that leprosy is usually transmitted through the air, and there is no evidence for sexual transmission, ² it is probably the close proximity (shared air space, including sleeping arrangements) which means that some spouses will be infected. Non-blood-related spouses may be at slightly lower risk than genetically related members of the household since inherited susceptibility plays a small part in risk for contacts. Segregation is not recommended for newly diagnosed patients and neither is sexual abstinence, since taking multidrug therapy leads to a rapid decrease in infectivity of the disease.

Physical examination of all household contacts on at least one occasion soon after the index case is diagnosed is not only a cost-effective way to identify other cases at an early stage, but also presents an opportunity for health education to the household members. ³

The authors do not state whether the male case had, on first presentation, any skin lesions which might have been tested for loss of sensation, but he did have thickened peripheral nerves – which is a diagnostic sign of leprosy. Nerve biopsies are rarely needed and can be harmful. It was unfortunate that he did not either receive multidrug therapy nor return for follow-up for the next seven months.

This patient also had peripheral nerve function impairment when first seen. In such a situation, it is imperative to ask the duration of impairment, since the probability of favourable response to steroids declines quickly as the delay before starting it increases. It is likely that when he was seen again and the lateral popliteal nerve damage had already been present for over six months, it was too late to expect reversal of that impairment after giving a steroid course. However, by then, he had sustained bilateral ulnar nerve impairment so there was a possibility that this might recover, so the steroid course was probably justified. ³ The female case also had nerve function impairment, but it is not clear how much earlier it had begun; evidently, the authors considered steroid treatment to be appropriate after reviewing the history.

Should the motor nerve function impairment not recover, it would be worthwhile to refer the patient for reconstructive surgery when he has been free from reaction/neuritis for six months or longer.

Both the man and the woman need to be educated about care of anaesthetic areas to prevent trophic ulceration. It was good to read that they had been taught about hand exercises to prevent development of contractures.

I was also pleased to read that skin smears had been used in the diagnostic work-up. The slit skin smear is a valuable but underutilised test, which can be done by any laboratory technician who is trained for staining and reading sputum for microscopy for tuberculosis, with the type of equipment usually available in a clinical laboratory. The result can be available more quickly than a histology report on a skin biopsy.

I agree with the authors that there is a need to undertake surveillance for leprosy in endemic areas as the disease has not been eliminated (only the public health problem has been ‘eliminated’). Apart from ‘active screening of all family members and close contacts’ ¹ of new cases of leprosy, what is important for early case detection is for all medical practitioners to be alert for suggestive signs of leprosy and conduct passive surveillance during their routine clinics. Physical examination and a slit skin smear are enough to confirm/exclude leprosy in a majority of patients with suggestive signs. Any suspected cases which they cannot manage themselves can be referred to a suitable specialist for a second opinion.

If any readers of Tropical Doctor need an easily accessible source of up-to-date information on leprosy (epidemiological or clinical), I would recommend the new multi-author open-access International Textbook of Leprosy, sponsored by American Leprosy Missions, available online at www.internationaltextbookofleprosy.org. Many chapters are already uploaded and the few still in preparation will appear very soon.

Yours faithfully,

C Ruth Butlin