Coinfection is the simultaneous infection of a host by multiple pathogen

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

. In virology, coinfection includes simultaneous infection of a single

cell Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery w ...

by two or more virus particles. An example is the coinfection of liver cells with hepatitis B virus and hepatitis D virus, which can arise incrementally by initial infection followed by

superinfection A superinfection is a second infection superimposed on an earlier one, especially by a different microbial agent of exogenous or endogenous origin, that is resistant to the treatment being used against the first infection. Examples of this in bact ...

. Global

prevalence In epidemiology, prevalence is the proportion of a particular population found to be affected by a medical condition (typically a disease or a risk factor such as smoking or seatbelt use) at a specific time. It is derived by comparing the number o ...

or incidence of coinfection among humans is unknown, but it is thought to be commonplace, sometimes more common than single infection. Coinfection with helminths affects around 800 million people worldwide. Coinfection is of particular human health importance because pathogen species can interact within the host. The net effect of coinfection on human health is thought to be negative. Interactions can have either

positive Positive is a property of positivity and may refer to: Mathematics and science * Positive formula, a logical formula not containing negation * Positive number, a number that is greater than 0 * Plus sign, the sign "+" used to indicate a posi ...

or negative effects on other parasites. Under positive parasite interactions, disease

transmission Transmission may refer to: Medicine, science and technology * Power transmission ** Electric power transmission ** Propulsion transmission, technology allowing controlled application of power *** Automatic transmission *** Manual transmission ** ...

and progression are enhanced and this is also known as syndemism. Negative parasite interactions include microbial interference when one bacterial species suppresses the virulence or

colonisation Colonization, or colonisation, constitutes large-scale population movements wherein migrants maintain strong links with their, or their ancestors', former country – by such links, gain advantage over other inhabitants of the territory. When ...

of other bacteria, such as '' Pseudomonas aeruginosa'' suppressing pathogenic '' Staphylococcus aureus''

colony In modern parlance, a colony is a territory subject to a form of foreign rule. Though dominated by the foreign colonizers, colonies remain separate from the administration of the original country of the colonizers, the '' metropolitan state'' ...

formation. The general patterns of ecological interactions between parasite species are unknown, even among common coinfections such as those between sexually transmitted infections. However,

network analysis Network analysis can refer to: * Network theory, the analysis of relations through mathematical graphs ** Social network analysis, network theory applied to social relations * Network analysis (electrical circuits) See also *Network planning and d ...

of a food web of coinfection in humans suggests that there is greater potential for interactions via shared food sources than via the immune system. A globally common coinfection involves tuberculosis and

HIV The human immunodeficiency viruses (HIV) are two species of ''Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune ...

. In some countries, up to 80% of tuberculosis patients are also HIV-positive. The potential for dynamics of these two infectious diseases to be linked has been known for decades. Other common examples of coinfections are

AIDS Human immunodeficiency virus infection and acquired immunodeficiency syndrome (HIV/AIDS) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV), a retrovirus. Following initial infection an individual ma ...

, which involves coinfection of end-stage

with opportunistic parasites and polymicrobial infections like Lyme disease with other diseases. Coinfections sometimes can epitomize a

zero sum game Zero-sum game is a mathematical representation in game theory and economic theory of a situation which involves two sides, where the result is an advantage for one side and an equivalent loss for the other. In other words, player one's gain is e ...

of bodily resources, and precise viral quantitation demonstrates children co-infected with rhinovirus and respiratory syncytial virus,

metapneumovirus ''Metapneumovirus'' is a genus of viruses in the family ''Pneumoviridae''. The genus contains two species: * Avian metapneumovirus Avian metapneumovirus (aMPV), also known as turkey rhinotracheitis or swollen head syndrome, causes a variety o ...

or parainfluenza virus have lower nasal viral loads than those with rhinovirus alone.

Poliovirus

Poliovirus is a positive single-stranded RNA virus in the family ''

Picornaviridae Picornaviruses are a group of related nonenveloped RNA viruses which infect vertebrates including fish, mammals, and birds. They are viruses that represent a large family of small, positive-sense, single-stranded RNA viruses with a 30 nm i ...

''. Coinfections appear to be common and several pathways have been identified for transmitting multiple virions to a single host cell. These include transmission by virion aggregates, transmission of viral genomes within membrane vesicles, and transmission by bacteria bound by several viral particles. Drake demonstrated that poliovirus is able to undergo multiplicity reactivation. That is, when polioviruses were irradiated with UV light and allowed to undergo multiple infections of host cells, viable progeny could be formed even at UV doses that inactivated the virus in single infections. Poliovirus can undergo genetic recombination when at least two viral genomes are present in the same host cell. Kirkegaard and Baltimore presented evidence that

RNA-dependent RNA polymerase RNA-dependent RNA polymerase (RdRp) or RNA replicase is an enzyme that catalyzes the replication of RNA from an RNA template. Specifically, it catalyzes synthesis of the RNA strand complementary to a given RNA template. This is in contrast to t ...

(RdRP) catalyzes recombination by a copy choice mechanism in which the RdRP switches between

(+)ssRNA Baltimore classification is a system used to classify viruses based on their manner of messenger RNA (mRNA) synthesis. By organizing viruses based on their manner of mRNA production, it is possible to study viruses that behave similarly as a dis ...

templates during negative strand synthesis. Recombination in RNA viruses appears to be an adaptive mechanism for transmitting an undamaged genome to virus progeny.

Examples

Anaplasmosis Anaplasmosis is a tick-borne disease affecting ruminants, dogs, and horses, and is caused by ''Anaplasma'' bacteria. Anaplasmosis is an infectious but not contagious disease. Anaplasmosis can be transmitted through mechanical and biological vector ...

* Bacteriophage coinfection * GB virus C * HIV-HCV coinfection * HIV-TB coinfection (enhances TB transmission and lethality) * Hepatitis D * Hookworm-malaria coinfection * ''

Mansonella perstans ''Mansonella perstans'' is a filarial (arthropod-borne) nematode (roundworm), transmitted by tiny blood-sucking fly, flies called midges. ''Mansonella perstans'' is one of two filarial nematodes that causes serous cavity filariasis in humans. ...

'' * Trichuriasis * Chikungunya and

Dengue Dengue fever is a mosquito-borne tropical disease caused by the dengue virus. Symptoms typically begin three to fourteen days after infection. These may include a high fever, headache, vomiting, muscle and joint pains, and a characteristic ...

coinfection *

and HIV coinfection (suppresses HIV) * Chagas and HIV coinfection * Most

sexually transmitted disease Sexually transmitted infections (STIs), also referred to as sexually transmitted diseases (STDs) and the older term venereal diseases, are infections that are spread by sexual activity, especially vaginal intercourse, anal sex, and oral s ...

s and HIV (enhance HIV transmission) * Some COVID-19 patients, or those who were ill with other coronaviruses, can be co-infected with seasonal influenza (flu) viral strains, certain viral strains that cause the

common cold The common cold or the cold is a viral infectious disease of the upper respiratory tract that primarily affects the respiratory mucosa of the nose, throat, sinuses, and larynx. Signs and symptoms may appear fewer than two days after exposur ...

, or can be co-infected with

bronchitis Bronchitis is inflammation of the bronchi (large and medium-sized airways) in the lungs that causes coughing. Bronchitis usually begins as an infection in the nose, ears, throat, or sinuses. The infection then makes its way down to the bronchi. S ...

or pneumonia from another bacterial or viral micro-organism. Even more dangerous, some of them could already have conditions like tuberculosis or active

that make patients very vulnerable.

References

External links

{{Medical resources , DiseasesDB = , ICD10 = , ICD9 = , ICDO = , OMIM = , MedlinePlus = , eMedicineSubj = , eMedicineTopic = , MeshID = D060085 Virology Epidemiology Infectious diseases