Infectious Disease

Spreading bacterial infection of the dermis and subcutaneous tissue that follows a breach in the skin barrier and tracks diffusely through tissue planes rather than forming a discrete collection.

Toxin-mediated colitis that follows antibiotic disruption of the normal gut flora, allowing a spore-forming organism to overgrow and damage the colonic mucosa.

A retroviral infection that progressively destroys CD4 T-helper cells, so that disease is defined not by the virus itself but by the opportunistic infections and cancers that emerge once immune surveillance collapses.

Acute inflammation of the gut caused by ingested pathogens or their toxins, producing diarrhoea and vomiting whose pattern and severity reflect the underlying mechanism of mucosal injury.

An acute respiratory viral infection whose rapid antigenic change allows it to repeatedly evade population immunity, producing seasonal epidemics and occasional pandemics.

A mosquito-borne protozoal infection of red blood cells whose species (above all, whether it is Plasmodium falciparum) determines how rapidly it can become life-threatening.

Inflammation of the meninges, most dangerously from bacterial invasion of the normally sterile subarachnoid space, where speed of antibiotic delivery, not diagnostic certainty, determines survival.

Life-threatening organ dysfunction caused not by infection alone but by a dysregulated host response to it, in which speed of recognition and treatment is the entire determinant of survival.

Chronic granulomatous infection with Mycobacterium tuberculosis, contained by cell-mediated immunity into a latent state in most people, but able to reactivate into active, transmissible disease when that containment fails.