Worldwide status of leprosis, its mite vector, and a case study: sampling, diagnostic and management of the disease in Brazil.

Brazil is the largest citrus producer in the world, and leprosis is currently considered the main viral disease for the Brazilian citrus industry due to the high costs spent for the chemical control of its vector, the tenuipalpid mite Brevipalpus sp. The global importance of leprosis has significantly increased in the last years, with the northbound spread of the virus to new regions of the American Continent. However, despite the worldwide distribution of its vector, there is no confirmation of the disease outside the Americas. Leprosis is endemic to the main citrus producing areas of Brazil and, even though there are several strategies available for its management, such as pruning of symptomatic branches, reduction of Brevipalpus populations with predaceous mites etc., the control of the disease is fundamentally based on the spray of pesticides after the action threshold for the mite is reached. Recent studies on the epidemiology of leprosis and on virus-vector interactions, however, strongly suggest that growers should take into consideration the presence of the disease ? and not only the vector - in the field for its proper control. Hence, the correct diagnosis of leprosis is essential for its management. Typical symptoms can be easily recognized by experienced personnel in endemic areas. Nevertheless, particularly for new areas, identifying leprosis symptoms may be somewhat challenging. In recent years, however, in addition to the examination of lesions using a transmission electron microscope, other molecular- or serological- based tools have being successfully used to confirm new cases of the disease. This workshop on citrus quarantine pests will bring several aspects on leprosis including a historical view of the disease, its main characteristics, alternatives for its management, its increasing economical importance in Brazil and abroad, and the new data on the search for understanding the interactions amongst the mite vector, the virus, and the plant host