Background: Leishmaniasis is a neglected disease with a global spread that affects both domestic and wild animals in addition to people. Leishmania donovani is the suspected anthroponotic cause of VL in India, where it is an endemic disease. The reservoir hosts play a crucial role in the life cycle of the Leishmania parasite. The complicated connection between the pathogen, vector, and reservoir exhibits geographical and temporal diversity. Human-to-human and, to a lesser extent, human-to-animal transmission is the principal mechanism for the maintenance of anthroponotic diseases. Scope and approach: A deliberate, systematic search was conducted on PubMed, Science Direct, and Google Scholar using keywords such as "Leishmania donovani," "zoonotic visceral leishmaniasis," and "wild animal reservoir for leishmania donovani." 530 potentially significant references were obtained from these 507 were disallowed due to copy avoidance, irrelevant titles, research publications from nations other than India, or modified compositions. The remaining 20 investigations were later rejected because they did not meet the criteria for inclusion. Finally 3 research papers with 867 goats, 161 cattles, 106 chickens, 26 sheep, 3 buffaloes, 406 dogs and 309 rats were reported. Conclusion: According to the review, goats are the epidemic's primary host and possible reservoir in several regions of India. In the endemic regions of the disease, some species of rodents along with the canines appear to be maintaining the L. donovani transmission cycle.

The immune system is a dynamic network of cells and cytokines are the major mediators of immune responses which combat pathogens. Based on the cytokine production, effector T cells differentiate into subsets known as Th1, Th2, Th17 or Treg (T regulatory). This system serves as a barrier to intracellular pathogens, bacterial infections and stimulates the production of reactive oxygen species (ROS), reactive nitrogen intermediates (RNI) and nitric oxide (NO), which diffuses across membranes and engulfs intracellular pathogens. Oxidative stress occurs when ROS, reactive nitrogen species (RNS) production and antioxidant defences become imbalanced. Oxidative stress generated by infected cells produces a substantial amount of free radicals which enables killing of intracellular pathogens. Intracellular pathogens are exposed to endogenous ROS as part of normal aerobic respiration, also aexogenous ROS and RNS are generated by the host immune system in response to infection. Nanoparticles which are designed for drug delivery are capable of trapping the desired drug in the particles which protects the drug from enzymatic degradation in a biological system. The small (subcellular) size of nanoparticles enables higher intracellular uptake of the drug which results in the reduction of the concentration of free drugs reducing their toxic effect. Research on the modulation of immune response and oxidative stress using nanoparticles used to encapsulate drugs has yet to be explored fully. In this review we illustrate the immune activation and generation of oxidative stress properties which are mediated by nanoparticle encapsulated drug delivery systems which can make the therapy more effective in case of diseases caused by intracellular pathogens.

Recent advancements in gut microbiome research have highlighted the complex interplay between gut microbiota and various physiological and pathological processes, showing that gut microbiota plays a vital role in human health and disease. Imbalances in the gut microbiota, known as dysbiosis, have been associated with a range of health conditions, including gastrointestinal disorders, metabolic diseases, etc. In response to these findings, probiotics, prebiotics, synbiotics, and postbiotics have emerged as a promising therapeutic strategy to modulate gut microbiota composition and functionality. This review paper explores the latest research on how gut microbiota impacts host physiology, immune responses, and overall well-being. Furthermore, the paper delves into the therapeutic potential of probiotics, postbiotics, prebiotics, and synbiotics in therapeutic applications and curing various diseases. The paper also addresses the challenges and opportunities in the field, highlighting the need for personalized approaches to probiotic therapy and the importance of considering factors such as strain specificity, dosing, and safety.Overall, this review aims to provide a comprehensive overview of the evolving landscape of gut microbiota and probiotics, prebiotics, synbiotics, and postbiotics as novel therapeutic agents. It underscores the potential of harnessing the gut microbiome to improve health, prevent diseases, and complement traditional medical interventions. As research in this field continues to expand, a deeper understanding of the gut microbiota and probiotics, prebiotics, synbiotics, and postbiotics promises new avenues for preventive and therapeutic healthcare strategies.