ABSTRACT
INTRODUCTION: Scrub typhus, a zoonotic disease is one of the most covert emerging and re-emerging Rickettsial infections. There is an upsurge in the incidence of the disease worldwide with ever-changing habitat. Clinical diagnosis of scrub typhus is challenging as the signs and symptoms of scrub typhus are similar to other febrile illnesses. In developing countries, among the various laboratory tests to diagnose scrub typhus, Weil-Felix test is commonly performed despite its low sensitivity. The Immunofluorescence antibody (IFA) test has its limitations in terms of cost and expertise required. The present study was conducted to determine the seropositivity of IgM ELISA for scrub typhus in clinically suspected cases. MATERIALS AND METHODS: Weil-Felix test and IgM ELISA were performed using clinically suspected cases of scrub typhus using commercially available kits. RESULTS: Out of 482 samples tested, 109 were positive by both Weil-Felix test and IgM ELISA. One hundred and sixteen samples which were negative by Weil-Felix test reacted positive by IgM ELISA. Fourteen samples which were positive by Weil-Felix test were negative by ELISA. CONCLUSION: Owing to the limitations of the Weil-Felix test and IFA, commercially available recombinant IgM ELISA which has a good sensitivity and specificity may be an alternative in laboratories with moderate set up.
ABSTRACT
BACKGROUND: The present study investigated the effect of chitosan seed priming on the induction of disease resistance in pearl millet against downy mildew disease caused by Sclerospora graminicola (Sacc.) Schroet. RESULTS: Pearl millet seeds were primed with chitosan at different concentrations: 0.5, 1.5, 2.5 and 3 g kg(-1) seed. Of the different concentrations, 2.5 g kg(-1) was found to be optimum, with enhanced seed germination of 99% and seedling vigour of 1782, whereas the untreated control recorded values of 87% and 1465 respectively. At optimum concentration, chitosan did not inhibit sporulation and release of zoospores from sporangia. Furthermore, pearl millet seedlings raised after seed treatment with chitosan showed an increased level of the defence-related enzymes chitosanase and peroxidase as compared with the untreated pearl millet seedlings on downy mildew pathogen inoculation. The effect of chitosan in reducing downy mildew incidence was evaluated in both greenhouse and field conditions, in which respectively 79.08 and 75.8% disease protection was obtained. CONCLUSION: Chitosan was effective in protecting pearl millet plants against downy mildew under both greenhouse and field conditions by inducing resistance against the pathogen. Thus, chitosan formulation can be recommended for seed treatment in the management of downy mildew disease.
