Although the lymphatic vessel system is almost as important as blood circulation, it is less widely known. It covers the human body like a net and fulfills many important functions. It not only plays an important role in the body's defense system, but it also transports up to four liters of lymph every day back out of the tissues.
Lymph is a fluid that contains dissolved substances such as blood proteins or metabolic breakdown products. If the system becomes diseased, return transport of the lymph fluid is no longer adequately ensured. The lymph pools and the affected parts of the body, usually the arms and legs, may develop enormous swelling. Elephantiasis is the most severe form of lymphedema.
Such conditions of the lymph vessel system can either be congenital and occur on its own by malformations of the lymphatic system (primary lymphedema) or be caused by another disease or condition (secondary lymphedema). The most common cause worldwide is a parasitic infection, where the parasite lodges itself in the lymphatic system, obstructing lymphatic vessels and disrupting the lymphatic flow.
Lymphatic filariasis, commonly known as elephantiasis
This is a neglected tropical disease where infection occurs when filarial parasites are transmitted to humans through mosquitoes. When lymphatic filariasis develops into chronic conditions, it leads to lymphedema (tissue swelling) or elephantiasis (skin tissue/thickening of limbs).
The global baseline estimate of people affected by lymphatic filariasis is over 15 million people living with lymphedema.