A pathogen (from Greek pathos, suffering/emotion, and gene, to give birth to), infectious agent, or more commonly germ, is a biological agent that causes disease or illness to its host. A biological agent is an Infectious disease or Toxin that can be used in Bioterrorism or Biological warfare. A disease is an abnormal condition of an organism that impairs bodily functions and can be deadly Illness (sometimes referred to as ill-health or ail) can be defined as a state of poor Health. In Biology, a host is an organism that harbors a Virus or Parasite, or a mutual or Commensal Symbiont, typically providing nourishment [1] However, pathogens can infect unicellular organisms from all of the biological kingdoms. A microorganism (also spelled micro organism or micro-organism and also called a microbe) is an Organism that is Microscopic (usually In biological Taxonomy, a kingdom or regnum is a Taxonomic rank in either (historically the highest rank or (in the new three-domain system The term pathogen is derived from the Greek "that which produces suffering. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly " There are several substrates and pathways where by pathogens can invade a host; the principal pathways have different episodic time frames, but soil contamination has the longest or most persistent potential for harboring a pathogen. Soil contamination is caused by the presence of man-made chemicals or other alteration in the natural soil environment
The body contains many natural defenses against some of the common pathogens (such as Pneumocystis) in the form of the human immune system and by some "helpful" bacteria present in the human body's normal flora. Pneumocystis pneumonia ( PCP) is a form of Pneumonia caused by the yeast-like Fungus, Pneumocystis jirovecii (Jirovecii is pronounced An immune system is a collection of mechanisms within an Organism that protects against Disease by identifying and killing Pathogens and Tumor The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have The human flora is the Microrganisms that constantly inhabit the Human body. However, if the immune system or "good" bacteria is damaged in any way (such as by chemotherapy, human immunodeficiency virus (HIV), or antibiotics being taken to kill other pathogens), pathogenic bacteria that were being held at bay can proliferate and cause harm to the host. Chemotherapy, in its most general sense refers to treatment of disease by chemicals that kill cells specifically those of micro-organisms or Cancer. Human immunodeficiency virus ( HIV) is a Lentivirus (a member of the Retrovirus family that can lead to acquired immunodeficiency syndrome In modern usage an antibiotic is a Chemotherapeutic agent with activity against Microorganisms such as Bacteria, fungi or Protozoa The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have Such cases are called opportunistic infections. An opportunistic infection is an infection caused by Pathogens that usually do not cause disease in a healthy Immune system.
Some pathogens (such as the bacterium Yersinia pestis, which may have caused the Black Plague, the Variola virus, and the Malaria protozoa) have been responsible for massive numbers of casualties and have had numerous effects on afflicted groups. Yersinia pestis (formerly Pasteurella pestis) is a Gram-negative rod-shaped Bacterium belonging to the family The Black Death, or the Black Plague, was one of the deadliest Pandemics in human history widely thought to have been caused by a bacterium named Yersinia Smallpox is an Infectious disease unique to humans caused by either of two virus variants named Variola major and Variola minor. Malaria is a vector -borne Infectious disease caused by Protozoan Parasites It is widespread in tropical and subtropical regions including Of particular note in modern times is HIV, which is known to have infected several million humans globally, along with Severe Acute Respiratory Syndrome (SARS) and the Influenza virus. Today, while many medical advances have been made to safeguard against infection by pathogens, through the use of vaccination, antibiotics, and fungicide, pathogens continue to threaten human life. Vaccination is the administration of Antigenic material (the Vaccine) to produce immunity to a disease In modern usage an antibiotic is a Chemotherapeutic agent with activity against Microorganisms such as Bacteria, fungi or Protozoa Fungicides are Chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores Social advances such as food safety, hygiene, and water treatment have reduced the threat from some pathogens. Food safety is a scientific discipline describing handling preparation, and storage of Food in ways that prevent Foodborne illness. Hygiene refers to practices associated with ensuring good health and cleanliness Water treatment describes those processes used to make water more acceptable for a desired end-use
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Types of pathogens
Below is a list of different types of notable pathogens as categorized by their structural characteristics, and some of their known effects on infected host.
Pathogenic bacteria
Although the vast majority of bacteria are harmless or beneficial, a few pathogenic bacteria cause infectious diseases. Pathogenic bacteria are Bacteria that cause Infectious diseases. The most common bacterial disease is tuberculosis, caused by the bacterium Mycobacterium tuberculosis, which kills about 2 million people a year, mostly in sub-Saharan Africa. Tuberculosis (abbreviated as TB for tubercle bacillus or T u' b' erculosis Bacillus --> is a common Mycobacterium tuberculosis is the Bacterium that causes most cases of Tuberculosis. Pathogenic bacteria contribute to other globally important diseases, such as pneumonia, which can be caused by bacteria such as Streptococcus and Pseudomonas, and foodborne illnesses, which can be caused by bacteria such as Shigella, Campylobacter and Salmonella. Pneumonia is an inflammatory illness of the Lung. Frequently it is described as lung Parenchyma / alveolar inflammation and abnormal Streptococcus is a Genus of spherical Gram-positive bacteria belonging to the phylum Firmicutes and the Pseudomonas is a Genus of gamma Proteobacteria, belonging to the larger family of Pseudomonads Recently 16S rRNA sequence This article is about the bacteria For the disease see Shigellosis Shigella is a Genus of Gram-negative The Genus Campylobacter, (meaning 'twisted bacteria' first discovered in 1963 describes Gram-negative, spiral Microaerophilic bacteria Salmonella is a Genus of rod-shaped Gram-negative enterobacteria that causes Typhoid fever, Paratyphoid fever Pathogenic bacteria also cause infections such as tetanus, typhoid fever, diphtheria, syphilis and leprosy. Tetanus is a medical condition that is characterized by a prolonged contraction of Skeletal muscle fibres Typhoid fever, also known as enteric fever, bilious fever, Yellow Jack or commonly just typhoid, is an illness caused by the Bacterium Diphtheria ( Greek διφθερα ( diphthera)—“pair of leather scrolls" is an upper respiratory tract illness characterized by sore Syphilis is a Sexually transmitted disease caused by the spirochetal Bacterium Treponema pallidum pallidum. Leprosy (from the Greek lepi (λέπι meaning scales on a fish or Hansen's disease, is a chronic disease caused by the bacterium Bacteria can often be killed by antibiotics.
Pathogenic viruses
- Further information: Table of clinically important viruses
Pathogenic viruses are mainly those of the families of: Adenoviridae, Picornaviridae, Herpesviridae, Hepadnaviridae, Flaviviridae, Retroviridae, Orthomyxoviridae, Paramyxoviridae, Papovaviridae, Rhabdoviridae, Togaviridae. Adenoviruses are medium-sized (90–100 nm) Nonenveloped (naked Icosahedral viruses composed of a nucleocapsid and a double-stranded linear DNA A Picornavirus is a Virus belonging to the family Picornaviridae. The Herpesviridae are a large family of DNA viruses that cause diseases in animals including humans Hepadnaviruses are a family of Viruses which can cause Liver infections in humans and animals The Flaviviridae are a family of Viruses that are primarily spread through arthropod vectors (mainly ticks and mosquitoes A retrovirus is any Virus belonging to the viral family Retroviridae. The Orthomyxoviridae (Derivation of name orthos is Greek for straight myxa is Greek for Mucus) are a family of RNA viruses that Paramyxoviruses are Viruses of the Paramyxoviridae family of the Mononegavirales order they are negative-sense single-stranded A Papovaviridae is a member of the Papovaviridae family of Viruses Papovaviridae includes two genera: Papillomavirus and Rhabdoviruses are Viruses belonging to the family Rhabdoviridae, which is in the order Mononegavirales. The Togaviridae are a family of Viruses including the following genera Genus Alphavirus; type species Sindbis virus Some notable pathogenic viruses cause: smallpox, influenza, mumps, measles, chickenpox and rubella. Ebola is another pathogenic virus.
Pathogen strength
A new theory regarding pathogens states that the longer a pathogen can survive outside of the body, the more dangerous it can be to a potential host. For example, the smallpox virus (variola virus) can survive outside the human body for approximately 885 days. It is also one of the most deadly pathogenic viruses, as it kills 1 in 10 of the people it infects. The tuberculosis bacterium kills 1 in 5 of the people it infects, but only survives 244 days outside of it's host. The Ebola virus has devastating results, 9 out of 10 people will die from it.
In countries that have higher sanitation standards, pathogens cannot survive for as long outside of the body. This means for the pathogen that genetic mutations causing it to become less deadly are preferable as they increase its survival chances inside a host.
Transmission of pathogens
One of the primary pathways by which food or water become contaminated is from the release of untreated sewage into a drinking water supply or onto cropland, with the result that people who eat or drink contaminated sources become infected. In Medicine, transmission is the passing of a Disease from an infected individual or group to a previously uninfected individual or group Water of sufficient quality to serve as drinking water is termed potable water whether it is used for drinking or not In developing countries most sewage is discharged into the environment or on cropland as of 12 August 1985; even in developed countries there are periodic system failures resulting in a sanitary sewer overflow. Developing countries are countries that haven't reached Western-style standards of democratic government free market economy industrialization social programs and human rights guaranties The term developed country, or advanced country, is used to categorize countries with developed Economies in which the tertiary and quaternary sectors Sanitary sewer overflow (SSO is a condition whereby untreated Sewage is discharged into the environment prior to reaching treatment facilities thereby escaping Wastewater
Examples of pathogens
References
- ^ http://www.medterms.com/script/main/art. Cholera, sometimes known as Asiatic cholera or epidemic cholera, is an infectious Gastroenteritis caused by the Bacterium Hepatitis A, (formerly known as infectious hepatitis) is an acute Infectious disease of the Liver caused by Hepatitis A virus which is Poliomyelitis, often called polio or infantile paralysis, is an acute viral Infectious disease spread from person to person primarily via Rotavirus is a Genus of Double-stranded RNA virus in the family Reoviridae. Ebola is the common term for a group of Viruses belonging to genus Ebolavirus, family Filoviridae, and for the disease which they
Dictionary
pathogen
-noun
- (pathology, immunology) Any organism or substance, especially a microorganism, capable of causing disease, such as bacteria, viruses, protozoa or fungi. Microorganisms are not considered to be pathogenic until they have reached a population size that is large enough to cause disease.
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