Nine-banded armadillo and leprosy research

In this presentation an attempt has been made to describe the nine-banded armadillo as an animal model, probably the only one in which lepromatous leprosy similar to that found in humans can be experimentally produced. Some unique features of the physiology of the animal are mentioned. The pathology and the microbiology of leprosy in the armadillo are described in detail. The discovery of lepromatous leprosy in the wild armadillos in the southern parts of United States, the transmission of disease among them through trauma and thorn pricks and the pathogenesis of the disease are presented. The impact of leprosy in the wild animals may have on human leprosy is discussed.

Dosage and site of entry influence growth and ddissemination of mycobacterium leprae in T900r mice

The role of dosage of Mycobacterium leprae and the environment of the inoculated site, in producing leprosy lesions in immunologically-suppressed, highly-susceptible T900r mice, was investigated. Various doses of M. leprae, i.e., 10(7), 10(6), 10(5), 10(4), were inoculated into both flanks and footpads of two different groups of mice. The sites of inoculation were biopsied for histopathological examination and for M. leprae counts at the end of 6, 8 and 12 months. M. leprae multiplied at the infected site and disseminated [figure: see text] to other parts of the body at all concentrations in the mice that were infected in the footpad with a temperature of 31 degrees C. In animals inoculated at the flanks with a temperature of 37 degrees C, multiplication was recorded only when the dosage of M. leprae was high and there was no dissemination of the organism in any of them. The temperature at the site of entry and the dose of infecting M. leprae may play an important role in the development of leprosy in susceptible individuals exposed to M. leprae.

Epithelioid granuloma in the iris of a lepromatous leprosy patient; an unusual finding

This case report depicts a case of histopathologically confirmed polar lepromatous (LL) leprosy with a bacterial index of 4+. He experienced recurrent episodes of erythema nodosum leprosum (ENL) in the first 5 years after diagnosis. Skin smears became negative after 6 years of dapsone monotherapy and have remained negative since that time. At 23 years after diagnosis, the patient had developed cataracts and underwent intracapsular cataract extractions with broad-based iridectomies. In one of the iris specimens, histopathologic examination revealed a focal granuloma composed of epithelioid cells. Subsequently a lepromin skin test showed a positive Mitsuda reaction with a borderline tuberculoid histopathology. This clearly illustrates the immunological upgrading of a polar lepromatous patient, perceived first in the iris tissue.

Comparative study of Mitsuda reaction to nude mouse and armadillo lepromin preparations using nine-banded armadillos

In 14 nine-banded armadillos the Mitsuda response to nude mouse-derived lepromin (lepromin-nu/nu) was compared to that of armadillo-derived lepromin (lepromin-A) by injecting the reagents intradermally into either side of the abdomen of the animal and examining the biopsies from the sites after 12 days. The histopathologic responses to both antigens were found to be similar, whether the animal was Mitsuda-negative (lepromatous) or Mitsuda-positive (tuberculoid). It is pointed out that armadillos are good experimental models for leprosy, and their use can replace humans in experimental studies.

Histopathological activity in paucibacillary leprosy patients after ROM therapy

Histopathological activity was assessed in the skin tissue of 13 skin-smear negative, borderline tuberculoid leprosy patients after administration of a single dose of ROM (rifampin 600 mg, ofloxacin 400 mg and minocycline 100 mg) therapy. Biopsies taken just before therapy showed Mycobacterium leprae to be present in eight cases. After 6 months, only three showed granulomatous lesions and others showed only resolving or inactive lesions. Acid-fast bacilli (AFB) persisted in the nerves of three cases. At the end of 12 months, granulomas persisted in 2 out of 13 (15%) patients. No bacilli, however, were detected in any of them at the end of 12 months. This study demonstrated that 12 months after a single dose of ROM granuloma cleared in 85% of the patients and AFB were absent in all of them.

Nasal mucosa and skin of smear-positive leprosy patients after 24 months of fixed duration MDT: histopathological and microbiological study

The skin and nasal mucosa of 10 lepromatous leprosy patients who had completed 24 doses of fixed duration multidrug therapy (MDT) but who continued to be skin-smear positive for acid-fast bacilli (AFB) were examined histopathologically. The nasal mucosa showed granuloma fractions that exceeded those seen in the skin specimens, signifying that activity in this region subsides much more gradually than the activity in the skin. Mouse foot pad studies done using T900r mice with an inoculum from the nasal mucosa biopsy specimens of these patients did not demonstrate any growth of Mycobacterium leprae, indicating that these bacilli were not viable. A skin specimen from one patient grew significant amounts of bacteria in the T900r mouse foot pad. These results show that 2 years of treatment with MDT would prevent dissemination of M. leprae from the nasal mucosa and, therefore, should preclude further transmission of the disease. It also indicates that viable bacteria might persist in the skin of patients, especially those with an initial bacterial index of > or = 4+ who have completed 24 doses of regular MDT. Therefore, a more cautious approach to administering only 12 doses of MDT to highly positive multibacillary patients is suggested.