Lymphangitis is an inflammation or an infection of the lymphatic channels that occurs as a result of infection at a site distal to the channel. It may present as long red streaks spreading away from the site of infection. It is a possible medical emergency as involvement of the lymphatic system allows for an infection to spread rapidly. The most common cause of lymphangitis in humans is bacteria, in which case sepsis and death could result within hours if left untreated. The most commonly involved bacteria include Streptococcus pyogenes (Group A strep) and hemolytic streptococci. In some cases, it can be caused by viruses such as mononucleosis or cytomegalovirus, as well as specific conditions such as tuberculosis or syphilis, and the fungus Sporothrix schenckii. Other causes of Lymphangitis could be from Arthropod bites and Iatrogenic causes. Lymphangitis is sometimes mistakenly called "blood poisoning". In reality, "blood poisoning" is synonymous with sepsis.
Lymphatic vessels are smaller than capillaries and tiny venules and are ubiquitous in the body. These vessels are fitted with valves to direct flow in only one direction. Fluid diffusing through the thin-walled small capillaries should be collected and the lymphatic system does just that: a fluid rich in protein, minerals, nutrients, and other substances useful for tissue growth. As well as essential nutrients, the lymphatic system can also transport or carry cancer cells, defective or damaged cells, and pathogens such as bacteria and viruses, as well as foreign bodies and organisms. The vessels of the lymphatic system all pass through lymph nodes, which function as filters for the lymph fluid before it is returned to the blood. The lymph nodes contain multiple types of white blood cells that when activated, can engulf or metabolize pathogens (bacteria and viruses) and defective or cancerous cells, preventing infections and malignant cancer cells from spreading.
