<unk>  is the simultaneous infection of a host by multiple pathogen species. In virology,<unk>  includes simultaneous infection of a single cell by two or more virus particles. An example is the<unk>  of liver cells with hepatitis B virus and hepatitis D virus, which can arise incrementally by initial infection followed by superinfection. Global prevalence or incidence of<unk>  among humans is unknown, but it is thought to be commonplace, sometimes more common than single infection.<unk>  with helminths affects around 800 million people worldwide.<unk>  is of particular human health importance because pathogen species can interact within the host. The net effect of<unk>  on human health is thought to be negative. Interactions can have either positive or negative effects on other parasites. Under positive parasite interactions, disease 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 of other bacteria, such as Pseudomonas aeruginosa suppressing pathogenic Staphylococcus aureus colony formation. The general patterns of ecological interactions between parasite species are unknown, even among common<unk> s such as those between sexually transmitted infections. However, network analysis of a food web of<unk>  in humans suggests that there is greater potential for interactions via shared food sources than via the immune system. A globally common<unk>  involves tuberculosis and HIV. 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<unk> s are AIDS, which involves<unk>  of end-stage HIV with opportunistic parasites and polymicrobial infections like Lyme disease with other diseases.<unk> s sometimes can epitomize a zero sum game of bodily resources, and precise viral quantitation demonstrates children co-infected with rhinovirus and respiratory syncytial virus, metapneumovirus or parainfluenza virus have lower nasal viral loads than those with rhinovirus alone.
Coinfection
Superinfection
Concomitant drug
Opportunistic infection
Intoxication
Breakthrough infection
Pesticide residue
Laboratory-acquired infection