Hooo-Hooo Volume 10, Nr 1 - Page 5

hosts acquiring a systemic infection upon direct or indirect exposure to the urine, blood or tissue of an infected animal. Leptospirosis seems to have been less well studied in wildlife - in epidemiological as well as many other aspects of the disease. This article will deal with the findings of a few recently published articles on leptospirosis with emphasis on wildlife. Classification of the organism Conventional classification of Leptospira is based on serological criteria dividing them into two species the pathogenic Leptospira interrogans sensu lato and the saprophytic Leptospira biflexa sensu lato. More than 60 serovars have been described for Leptospira biflexa. Currently more than 250 serovars separated into 25 serogroups are recorded Leptospira interrogans. The serological classification system is also complemented by a genotypic classification, in which 21 genetic species are currently recognized, which would include pathogenic, intermediate and non-pathogenic (or saprophytic) species. Epidemiology The epidemiology of leptospirosis is complex and transmission of infection involves recirculation of the pathogens among domestic and wild animal reservoirs. Rodents are recognized as one the most important sources of infection through persistent renal carriage stages resulting in urinary shedding of Leptospira. Multiple factors in complex systems determine the occurrence of epidemic outbreaks in humans or animals. Weather-related threats, such as the El Niño phenomenon, high rainfall season, flooding, environmental disasters, water consumption, water sports and occupational exposure may be associated with outbreaks of leptospirosis. As fresh water has been considered a source of leptospirosis the survival and the preservation of the virulence of pathogenic Leptospira spp were investigated by Andre-Fontaine et al (2015) - in five still waters with various pH and mineral profiles. They found the mean survival was 130 days for storage at 4 °C, 263 days at 20 °C, and 316 days at 30 °C. Pathogenic strains remained fully virulent and were able to induce lethal disease in gerbils even when the pH of the contaminated waters decreased to < 6. This study confirmed that despite unfavourable storage conditions (cold and nutrientpoor acidic waters), the survival and virulence of pathogenic Leptospira spp was fully preserved over at least 20 months. The rise in global travel and ecotourism has also led to dramatic changes in the epidemiology of leptospirosis and this was reviewed in an article by Bandara et al (2014). Despite decreasing prevalence of leptospirosis in endemic regions, previously non-endemic countries are now reporting increasing numbers of cases due to recreational exposure. In global context, the disease is widespread and considered as emerging or re-emerging, according to the geographical area and time, or as neglected. Lindsey et al (2009) reported wildlife ranching to be increasingly recognised as a productive form of land use on marginal lands where alternatives such as agriculture are far less viable. Other developments were legislative changes during the 1960–70s which granted landowners the right to utilize wildlife on their land. Due to a combination of a rising demand for tourism and safari hunting, recurrent droughts, overstocking with livestock blamed for range degradation and reduced productivity which coincided with declining state subsidies for livestock production it has resulted in a huge shift from livestock farming to wildlife ranching in many parts the South African region. Citing Zimbabwe, South Africa and Namibia as examples: In Zimbabwe 1,000 wildlife ranches were developed, covering and area of 27,000 km2 (prior to the land seizures in 2000), in South Africa 9,000 wildlife ranches covers 205,000 km2 in addition to 15,000 mixed livestock and wildlife ranches whilst in Namibia, wildlife ranches and communal conservancies encompass 288,000 km2 . In many other parts of Africa wildlife numbers may have declined and habitat may have shrunk but the bush meat trade remains of great economic 2016 MARCH 5