Communicable Diseases and Pathogens
Your body is constantly under attack from tiny invaders called pathogens - bacteria, viruses, protists, and fungi that can make you seriously ill. These microscopic troublemakers spread through coughing, sneezing, contaminated food and water, or direct contact with infected people.
Viruses like measles, HIV, and tobacco mosaic virus are particularly sneaky because they can't reproduce on their own. Instead, they hijack your cells' machinery, multiply rapidly, then burst out to infect other areas. HIV is especially dangerous as it attacks your immune system directly, eventually leading to AIDS if untreated.
Bacteria such as Salmonella and Gonorrhoea can reproduce themselves and produce harmful toxins that damage your cells and tissues. Meanwhile, fungi cause diseases like rose black spot in plants, and protists like malaria are often spread by vectors (carriers like mosquitoes that don't get the disease themselves).
Remember: Pathogens need specific conditions to spread - good hygiene, isolation of infected people, and vaccination programmes can stop outbreaks before they become epidemics.
