Microsporidia are a group of obligate intracellular fungi that were initially classified as protists but were later reclassified based on phylogenetic, molecular, and structural evidence linking them to the Chytridiomycota. These unicellular, non-motile organisms are highly specialized parasites that infect a wide range of animal hosts, including humans. They have evolved extensive genomic and metabolic reductions, making them highly dependent on their hosts for survival.Morphology and Genomic...

Alveolates are a group of organisms recognized by the presence of alveoli, which are cytoplasmic sacs located beneath the cell membrane. While their function remains uncertain, alveoli may help regulate water balance by controlling how much water enters and leaves the cell. In dinoflagellates, these structures may serve as armor plates. There are three major types of alveolates: ciliates, which move using cilia; dinoflagellates, which use flagella for movement; and apicomplexans, which are...

Pathogen colonization of host tissues is a critical step in the development of infectious diseases. Various pathogenic microorganisms, including bacteria, fungi, viruses, and protozoa, have evolved complex strategies to attach to, invade, and persist within host environments. These mechanisms enable pathogens to establish infections, evade immune responses, and resist antimicrobial treatments.Attachment to Host CellsIn bacteria, colonization typically begins with adherence to host epithelial...

Excavata is a diverse group of protists that includes both chemoorganotrophic and phototrophic species, with some thriving in anaerobic environments. Among the key groups within Excavata are diplomonads and parabasalids, which are flagellated protists that lack mitochondria and chloroplasts. These microorganisms typically inhabit anoxic environments, such as the intestines of animals, where they exist either symbiotically or as parasites, relying on fermentation for energy production. Some...

Bacterial gastroenteritis, characterized by diarrhea, abdominal cramps, and vomiting, is often caused by ingestion of contaminated food or water and is frequently associated with pathogenic Escherichia coli strains. These microbes exploit two principal mechanisms to inflict disease.Shiga toxin–producing E. coli, also referred to as STEC—notably O157:H7—release Shiga toxins that target ribosomes, blocking protein synthesis. The B subunit of the toxin binds the host glycolipid receptor...

When a pathogen enters the body and reproduces, it can cause an infection, damage body cells, and cause illness symptoms that eventually lead to disease. Therefore, its prevention requires breaking the chain of infection.
The chain begins with pathogens: bacteria, viruses, fungi, prions, or parasites such as protozoa helminths. These can be present on the skin as transient or resident flora, or they can be acquired from the environment. Identifying and treating the type of infection and...