Limiting the transmission of leptospirosis to humans
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Leptospirosis, a zoonotic disease, is transferable through wild animals to other animals and humans directly and indirectly through contact with urine on mucous membranes. This disease can pose hazards for humans because of their increased contact with wild animals through increased urbanization and greater wildlife rehabilitation efforts and also through increased contact with domesticated animals. Furthermore, humans also have the potential of contracting this potentially fatal disease through recreational activities in contaminated waters or soils. The disease can present itself mildly, similar to symptoms of the flu, or more severely, leading to end-organ damage of multiple systems. Having been reinstated as a nationally notifiable disease by the Centers for Disease Control and Prevention in January 2013, leptospirosis has been recognized as a re-emerging zoonosis that has global public health implications. Understanding the disease is important in limiting its transmission; thus, this thesis aims to provide a review of the biology and transmission of leptospirosis to animals and humans, providing a basis in understanding the possible ways to limit the transmission and prevent future outbreaks. Furthermore, this thesis describes the manifestations, diagnostic testing, and treatment options for leptospirosis in canines and humans, as the increased prevalence of canines in households may pose a risk to humans in the future in the transmission of leptospirosis. According to current research, leptospires are extremely viable bacteria that can survive for long periods of time in a variety of environments and host species. Researchers have conducted various experiments to evaluate the factors that increase the virulence of leptospires. Experiments include the osmolarity, presence of serum, temperature chances, and the presence of iron. Results demonstrate that virulence increases with increased osmolarity, presence of serum, increased temperature, and the presence of iron. These characteristics of pathogenic leptospires allow them to avoid destruction by the immune system and colonize in the host, specifically in the renal tubules, allowing for excretion into the environment. Limiting the transmission of the disease is very important to prevent future outbreaks for animal species and humans. One method of limiting this transmission includes the use of vaccines. A major issue is the transmission of disease surround renal shedding, or excretion of the bacteria in urine. Canine polyvalent vaccines, containing multiple serovars, have been proven to be effective for a year, providing immunity and decreasing renal shedding of the bacteria. While vaccines for humans have been developed, they are not widely used due to the variation of serovars that are able to infect humans around the world and also the geographic distribution of disease, with prevalence mainly in tropical regions. Since leptospirosis is a disease that is not well-known, but can be found globally, there is necessity for greater emphasis on education, improved diagnostic testing, and treatment regimens. Emphasis on education is not only important for future veterinarians but also for those working in at-risk occupations. Furthermore, since experiments have shown that pet owners may not be aware of the prevalence and danger of zoonotic diseases, veterinarians should provide education for pet owners as well. Currently, the disease is underreported, which is accounted for due to the currently used diagnostic methods that are not efficient for early diagnosis, such as microscopic agglutination test, polymerase chain reaction, and cultures. In regards to treatment, antimicrobial treatment is considered controversial and there is not an agreed upon method of treatment. Thus, an emphasis should be placed on a developing a treatment method that is able to directly affect leptospires and usable across varying populations.