Molecular detection of Mycobacterium leprae using RLEP-PCR in post elimination era of leprosy.

Leprosy is considered as a contagious disease and is still a health problem in several countries including India. Diagnosis of leprosy is based either on clinical findings or on acid fast bacilli staining. Due to low sensitivity of acid fast bacilli staining most of the leprosy cases were remained undetected. The present study aims to assess the efficacy of RLEP-PCR in the field condition where majority of the patients are acid fast bacilli negative and have early disease. A total of 80 suspected leprosy cases were recruited. Slit skin smear samples were taken for microscopy and molecular experimentation. DNA was extracted and RLEP-PCR was executed for all the 80 samples. To establish the statistical correlation χ2 test and Fisher's exact test were made. To elucidate the sensitivity of the test Receiver Operating Characteristic (ROC) was drawn. These 80 leprosy patients comprised of 38 paucibacillary and 42 multibacillary leprosy cases. Of 80 leprosy patients 18 (22.5%) were AFB positive while 53 (66.25%) leprosy cases were RLEP-PCR positive. The results of test of significance (P=0.0001) and Cohen's kappa coefficient (κ) (0.614) indicated that the RLEP-PCR is a better diagnostic tool over AFB microscopy in case detection of leprosy. From the findings we concluded that RLEP-PCR could be used for the definitive detection of leprosy cases in accordance with the clinical findings in the field condition in the post elimination era of leprosy.

Multiple strain infection of Mycobacterium leprae in a family having 4 patients: A study employing short tandem repeats.

BACKGROUND: Leprosy is a slow, chronic disorder caused by Mycobacterium leprae. India has achieved elimination of leprosy in December 2005 but new cases are being detected and continue to occur in some endemic pockets. The possible ways of transmission of leprosy is not fully understood and is believed that leprosy is transmitted from person to person in long term contact. Studying the transmission dynamics is further complicated by inability to grow M. leprae in culture medium and lack of animal models. More than one family members were found to be affected by leprosy in some highly endemic pockets. This study reported the transmission pattern of leprosy in a family having 4 patients. METHODOLOGY/PRINCIPAL FINDINGS: We investigated the transmission of leprosy in a single family having 4 patients using microsatellite typing. DNA was isolated from slit skin smear samples taken from the patients and the isolated DNA were amplified using microsatellite loci TA11CA3. The amplified products were sequenced using Sanger's sequencing methods and the copy number variation in the microsatellite loci between strains were elucidated by multiple sequence alignment. The result showed that all the 4 members of the family acquired infection from 3 different strains of M. leprae from 3 different sources. The elder and middle daughters were infected by same types of strains having the repeat unit TA13CA3 and could have acquired the infection from social contacts of leprosy cases while the father and younger daughter were infected by strains with the repeat unit TA12CA3 and TA11CA3 and could have acquired infection from social contacts. CONCLUSIONS/SIGNIFICANCE: The study suggested that three family members viz, elder daughter, father and younger daughter could be infected by M. leprae from 3 different sources and the history of the disease and genetic analysis showed that the middle daughter acquired infection from her elder sister in due course of contact. This study implies that the transmission of leprosy not only occurred amongst the house hold members but also has been transmitted from social and neighborhood contacts in long term association with the them.

What is the appropriate duration of a therapeutic trial in cutaneous tuberculosis? Further observations.

BACKGROUND: Laboratory tests for the diagnosis of cutaneous tuberculosis lack adequate sensitivity and specificity and a trial of therapy is often used as a diagnostic test in difficult cases. However, the duration for which the trial should be undertaken is not clearly defined. Our previous study indicated that one month of therapy was adequate to detect a clinical response to treatment. However, about half the patients first reported after one month of treatment, some much later. METHOD: We therefore analysed the treatment records of 107 patients who received four-drug, short course, antitubercular therapy for a diagnosis of cutaneous tuberculosis in our hospital and who were asked to return for follow-up at biweekly intervals in the first month of treatment. RESULT: Twenty-one patients did not return for any follow-up visit, nine patients did not respond to treatment and treatment was stopped in one patient. Of the remaining 76 patients, 72 patients were recorded to have distinct clinical improvement within five weeks of starting treatment while only four patients showed improvement after 60-123 (8-17 weeks) days of therapy. CONCLUSION: These findings indicate that five weeks appears to be an adequate duration of a therapeutic trial in patients suspected to have cutaneous tuberculosis, with the exception of tuberculids and patients showing minimal clinical activity before treatment. Patients who have not responded by this time are unlikely to do so with further treatment and should have their diagnosis reviewed.

Cutaneous horn and thermal keratosis in erythema AB igne.

A 46-year-old Kashmiri lady developed erythema ab igne on both legs. She subsequently developed multiple keratoses and a cutaneous horn in the involved skin. An uncommon association of these three clinical conditions is being presented.