Can sandflies be the vector for leprosy?
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Biomedical subjects
Publications and source records attributed to K V Desikan.
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An assessment has been made of 108 neuritic leprosy patients to find out if the number of affected nerves and the clinical presentations of these patients give any indication of the underlying severity (classification) of the disease. Detailed clinical recordings, skin smears, lepromin testing with Dharmendra antigen, and a leukocyte migration inhibition test (LMIT) using sonicated Mycobacterium leprae antigens were done in these patients. Nerve biopsies of available affected nerves were taken in 39 patients. The results show that neuritic leprosy patients also have a spectrum. However, none of the clinical parameters, including the number and distribution of affected nerves, the immune response and the nerve histology, were found to be inter-related. Further, even though all of the patients were skin-smear negative, a significant proportion showed lepromatous histology and nearly two thirds had a moderate-to-heavy bacterial load within the nerves.
The length of treatment advocated for leprosy has been very long and arbitrary. During the past few years, attempts have been made to reduce the length of treatment required. World Health Organization (WHO) has recommended six months therapy for paucibacillary leprosy. The present study was undertaken to see the extent of histological changes that occur with this therapy. Thirty four untreated tuberculoid (TT/BT) leprosy patients were biopsied initially and after completion of fixed course of this treatment. Clinically, 50 percent of the patients showed regression of disease activity at the end of six months. Morphology of the lesions was studied, in clinically active and inactive cases on completion of therapy. It was found that after six month's therapy, histology of the lesions was similar, whether the case was active or not. After the prescribed treatment, biopsy showed marked reduction in the extent of granuloma, along with significant increase in lymphocytes and a increase in epithelioid cells in these granulomas.
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Skin smear direct microscopy is an important tool for diagnosis of leprosy. The study was planned to understand the reproducibility of skin smear reading by a trained technician. Skin smears were collected from known patients of leprosy from the field area. They were stained for acid fast bacilli following the standard cold staining procedure and were read following the Ridley scale. A sample of smears was re-examined on two occasions by the same technician, following blind procedure. There was a systematic under reading on the second occasion, which was attributed to the defective storage of the slides. However, the agreement between second and third examinations was very good (Concordance 81.34%, Kappa 0.74). The finding was confirmed on a repeat examination. It can be concluded that the Direct Skin Smear Microscopy is a reliable and reproducible technique under experimental conditions.
Sera from 478 persons (348 leprosy patients, 33 tuberculosis patients, 29 healthy contacts of leprosy patients, 38 normal healthy Indians, and 30 normal healthy Europeans) were screened for anti-HIV-1 IgG antibodies by ELISA. None was positive. In addition, 132 samples (from 43 leprosy patients, 21 tuberculosis patients, 5 healthy contacts of leprosy patients, 33 normal healthy Indians, and 30 normal healthy Europeans) were also tested by Western blot assay for anti-HIV-1 IgG antibodies. Only 1 of the 63 healthy subjects expressed a prominent p17 band. One or more bands were found in 44 (leprosy patients 33/43, tuberculosis patients 7/21, and leprosy contacts 4/5) of the remaining 69 sera. Antibody to the HIV-1-specific antigen p24 was expressed by 17 of these subjects (14/43 leprosy patients, 1/21 tuberculosis patients, and 2/5 leprosy contacts), either as a single band or in combination with other bands. This raises the possibility of a common antigenic pattern between HIV-1 and mycobacteria, especially Mycobacterium leprae.
Delayed-typed hypersensitivity (DTH) response and protection value of some of the candidate vaccines alone and in combination with BCG has been investigated. It was observed that both M.w. and BCG gave heightened DTH and good protection. On the other hand both M. leprae and ICRC evoked moderate DTH and gave poor protection. However on combining any of these candidate vaccines with live BCG, the lowering of DTH and poor protection was observed except in the M. leprae combination which in spite of low DTH gave better protection.
A retrospective study is presented herewith of 94 cases classified as BT and treated with sulphone monotherapy. A system of scoring based on the number and extent of lesions, and nerve involvement was followed. It was observed that cases with a clinical score of 2 or having more than 15 lesions or patients with extensive lesions covering 3 or more of 7 sectors of the body had a bad prognosis in respect of time taken for subsidence, occurrence of deformities and most importantly occurrence of relapses. Hence it is suggested that such cases should be considered as Multibacillary and treated as such, despite bacteriological findings which may be either negative or a bacteriological positivity of less than 2 at any one site.
The response to standard Dharmendra lepromin and the circulating T, B cell numbers in the peripheral blood were quantitated in 15 patients with Borderline (BB) Leprosy. On the basis of lepromin response, the patients fall into three groups (a) negative (b) +/- reaction (c) rarely positive. No significant difference in the numbers of E-rosette and EAC rosette forming cells was observed in the BB patients in comparison to controls.
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Three regimens containing rifampin have been tried in paucibacillary leprosy patients. The patients were selected according to the criteria laid down by the World Health Organization (WHO). In Regimen I, rifampin 600 mg is given once a month for 6 months with dapsone 100 mg daily. Treatment is stopped at the end of 6 months. Regimen II is the same as Regimen I, and is supplemented with an additional 6 months' treatment with dapsone 100 mg daily. Regimen III is the same as Regimen II, except that rifampin is administered daily for the first 7 days. At the end of the scheduled treatment period, 72.2% of the patients in Regimen I, 94.9% of the patients in Regimen II, and 97.1% in Regimen III became inactive. Eighteen out of the 25 active cases at the time Regimen I treatment was stopped had to be restarted on drug therapy since they showed a worsening of their disease, as indicated by an increase in their bacterial index, the appearance of new lesions, renewed activity in old lesions, an increase in the size of old lesions, or development of nerve abscesses. The remaining seven cases regressed without further treatment. All four Regimen II patients and two Regimen III patients who had evidence of activity at the time treatment was stopped did not require any further treatment. On follow-up for 1 1/2 years, three Regimen I patients and none of the Regimen II or Regimen III patients showed relapses. It is thus apparent that rifampin helps to shorten the time duration and to increase the cost effectiveness of treatment of paucibacillary leprosy cases.(ABSTRACT TRUNCATED AT 250 WORDS)
A study was made on the Langerhans' cells at the sites of contact sensitivity skin reactions in 45 untreated leprosy patients. The skin reaction was induced by 2,4-dinitrochlorobenzene (DNCB). Langerhans' cells were quantitated using OKT6 monoclonal antibody and indirect immunofluorescence. Clinically, the skin reaction in the tuberculoid patients was positive at 4, 24, and 48 hr, while the lepromatous patients failed to respond at any of the time intervals. Sequential histological analysis of the skin reaction showed predominantly mononuclear cell infiltrates around the blood vessels and neurovascular bundles in both the tuberculoid and lepromatous patients. Time kinetic assessment showed no difference in the numbers and distribution of OKT6+ epidermal Langerhans' cells at the site of the DNCB skin reactions among the tuberculoid and lepromatous patients. This, therefore, suggests that either there is a functional defect in Langerhans' cells or some other mechanism(s) such as a T-cell abnormality is responsible for the lack of clinical reaction in lepromatous patients.
Punch biopsies taken 12, 24, 48, and 72 hours after skin testing with Leprosin A have been used to prepare ultrathin sections for the identification and enumeration of infiltration cells. The study was performed on small numbers of both healthy persons and leprosy patients with various forms of the disease living in India. Similar cells were found to infiltrate both positive and negative responses to the skin test reagent, although there were quantitative differences. The most striking findings were the absence of the expected basophils and an infiltration of eosinophils which proceeded to degranulate. This was especially noticeable in a healthy leprosy contact and in patients at the tuberculoid end of the leprosy spectrum, whether or not they produced positive skin reactions to Leprosin A. In patients at the lepromatous end of the spectrum, infiltrates were largely neutrophils.
Single-cell suspensions from the granulomas of leprosy cases were prepared for an in vitro study of the properties of the infiltrating cells. Biopsies from 44 untreated patients with tuberculoid and lepromatous leprosy were analyzed. The granulomas were found to contain lymphocytes and "large cells" (epithelioid cells and macrophages). The number of lymphocytes was significantly higher in the suspensions from the tuberculoid granulomas in comparison to the suspensions from the lepromatous granulomas. A high percentage of lymphocytes from the tuberculoid granulomas formed rosettes with sheep erythrocytes, and also showed the presence of esterase as dots in the cytoplasm. However, the lymphocytes did not form rosettes with EAC. Most of the "large cells" from both types of granulomas were esterase positive, exhibited peroxidase activity, and did not carry receptors for C3. A high percentage of "large cells" in the tuberculoid granulomas was nonadherent to a plastic surface, while the lepromatous granulomas contained a high proportion of adherent "large cells."
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The medium 'V' has been evaluated for the in vitro growth of M. leprae. M. leprae were obtained from five untreated cases of multibacillary type of leprosy. Medium was prepared and inoculated by the method described by Veeraraghavan. Killed (Autoclaved) M. leprae from the same biopsies were kept as controls. Growth was monitored in a double blind manner at 60 hours, 120 hours of incubation at 8-10 degrees C of both primary and subcultures. Counting was done by both standard Shepard and McRae method as well as by Veeraraghavan's method. There was no evidence of any multiplication in any of the cases at 60 and 120 hours of incubation.