A sapronosis is an

infectious disease An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dise ...

caused by an organism that is able to live and reproduce in the

soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...

or an other abiotic environment, and infects a living host directly from that environment. One widely-known example of a sapronosis is

Legionnaire's disease Legionnaires' disease is a form of atypical pneumonia caused by any species of ''Legionella'' bacteria, quite often '' Legionella pneumophila''. Signs and symptoms include cough, shortness of breath, high fever, muscle pains, and headaches. Naus ...

. Approximately a third of all known disease organisms are sapronoses. Almost all

fungal infection Fungal infection, also known as mycosis, is disease caused by fungi. Different types are traditionally divided according to the part of the body affected; superficial, subcutaneous, and systemic. Superficial fungal infections include common ti ...

s are sapronoses, but there are no known sapronotic viruses. Occupation often plays a role in sapronoses: people working with the soil, such as farmers or gardeners, are often at particularly high risk.

Sporotrichosis Sporotrichosis, also known as rose handler's disease, is a fungal infection that affects skin, lungs, bone and joint, and can be widespread. It presents with firm painless Nodule (medicine), nodules that later ulceration, ulcerate. It can be local ...

, a fungal sapronosis, is for example sometimes known as "rose handler's disease". Sapronoses pose unique public health challenges. Because they can persist in the environment outside of any living host, they are difficult to control or eradicate. Their spread is also not subject to

threshold host density Threshold host density (NT), in the context of wildlife disease ecology, refers to the concentration of a population of a particular organism as it relates to disease. Specifically, the threshold host density (NT) of a species refers to the minimu ...

. Sapronotic outbreaks are typically caused by a common source material, can be stopped by removing that material. For example, an outbreak of sporotrichosis that affected more than 3000 South African miners was stopped by removing wood in which the fungus was living.

Terminology and classification

The term "sapronosis" was coined by the Russian microbiologist Vasiliy Ilyich Terskikh in 1958, who contested the then-widespread idea that pathogenic bacteria could not persist in the environment outside of a host. Sapronoses sometimes serve as one part of the three-part classification of infectious diseases; the other two parts are anthroponoses (spread mostly from human to human) and

zoonoses A zoonosis (; plural zoonoses) or zoonotic disease is an infectious disease of humans caused by a pathogen (an infectious agent, such as a bacterium, virus, parasite or prion) that has jumped from a non-human (usually a vertebrate) to a human. ...

(spread mostly from animals to humans). In contrast to those, the primary

reservoir A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including contro ...

of a sapronosis is in the soil. Sapronoses are therefore sometimes distinguished from environmental pathogens, also called "saprozoonoses", which have one part of their life cycle in the soil and one part in an animal host. Typical examples of sapronotic agents are fungal such as coccidioidomycosis, histoplasmosis,

aspergillosis Aspergillosis is a fungal infection of usually the lungs, caused by the genus ''Aspergillus'', a common mould that is breathed in frequently from the air around, but does not usually affect most people. It generally occurs in people with lung dise ...

cryptococcosis Cryptococcosis is a potentially fatal fungal infection of mainly the lungs, presenting as a pneumonia, and brain, where it appears as a meningitis. Cough, difficulty breathing, chest pain and fever are seen when the lungs are infected. When the ...

, ''Microsporum gypseum''. Some can be bacterial from the

sporulating In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...

clostridium ''Clostridium'' is a genus of anaerobic, Gram-positive bacteria. Species of ''Clostridium'' inhabit soils and the intestinal tract of animals, including humans. This genus includes several significant human pathogens, including the causative ag ...

and bacillus to ''Rhodococcus equi, Burkholderia pseudomallei, Listeria'', ''Erysipelothrix'', ''Yersinia pseudotuberculosis,'' legionellosis, Pontiac fever, ''and'' nontuberculous mycobacterioses. Other sapronotic agents are amebic as in primary amebic meningoencephalitis. Yet again, difficulties in classification arise in the case of sporulating bacteria whose infectious spores are only produced after a significant period of inactive

vegetative Vegetative describes vegetation. Vegetative may also refer to: *Vegetative reproduction Vegetative reproduction (also known as vegetative propagation, vegetative multiplication or cloning) is any form of asexual reproduction occurring in ...

growth within an abiotic environment, yet this is still considered a case of sapronoses.

References

{{Concepts in infectious disease Disease ecology Infectious diseases

Terminology and classification

See also

References