Q.What does the term Zoo-anthroponosis refer to?

A pathogen is any organism capable of causing disease in a host. Across this chapter, pathogens are grouped by biological kingdom, and each group tends to share transmission patterns and disease mechanisms.

Bacteria are pathogenic in only a small fraction of species; they spread via air, water, droplets/aerosols, or shared personal items, and often damage tissue by releasing toxins (e.g. Corynebacterium diphtheriae in diphtheria, Clostridium tetani in tetanus). Viruses are obligate intracellular parasites — inert outside a host cell but capable of hijacking a cell's machinery once inside to replicate and then destroy it, spreading to further cells; they are classified by which body system they preferentially damage (pneumotropic, dermotropic, viscerotropic, neurotropic). Protozoan parasites such as Entamoeba, Trypanosoma, Leishmania and Plasmodium live inside body tissues or blood, often relying on an insect vector (mosquito, tsetse fly, sandfly) to complete their life cycle. Fungal pathogens (Trichophyton, Microsporum, Epidermophyton) cause surface/cutaneous infections favoured by heat and mois …