<Li> The disease might be dangerous to other patients, and the patient might have to be isolated </Li> <P> A number of studies have reported associations between pathogen load in an area and human behavior . Higher pathogen load is associated with decreased size of ethnic and religious groups in an area . This may be due high pathogen load favoring avoidance of other groups, which may reduce pathogen transmission, or a high pathogen load preventing the creation of large settlements and armies that enforce a common culture . Higher pathogen load is also associated with more restricted sexual behavior, which may reduce pathogen transmission . It also associated with higher preferences for health and attractiveness in mates . Higher fertility rates and shorter or less parental care per child is another association that may be a compensation for the higher mortality rate . There is also an association with polygyny which may be due to higher pathogen load, making selecting males with a high genetic resistance increasingly important . Higher pathogen load is also associated with more collectivism and less individualism, which may limit contacts with outside groups and infections . There are alternative explanations for at least some of the associations although some of these explanations may in turn ultimately be due to pathogen load . Thus, polygny may also be due to a lower male: female ratio in these areas but this may ultimately be due to male infants having increased mortality from infectious diseases . Another example is that poor socioeconomic factors may ultimately in part be due to high pathogen load preventing economic development . </P> <P> Evidence of infection in fossil remains is a subject of interest for paleopathologists, scientists who study occurrences of injuries and illness in extinct life forms . Signs of infection have been discovered in the bones of carnivorous dinosaurs . When present, however, these infections seem to tend to be confined to only small regions of the body . A skull attributed to the early carnivorous dinosaur Herrerasaurus ischigualastensis exhibits pit - like wounds surrounded by swollen and porous bone . The unusual texture of the bone around the wounds suggests they were afflicted by a short - lived, non-lethal infection . Scientists who studied the skull speculated that the bite marks were received in a fight with another Herrerasaurus . Other carnivorous dinosaurs with documented evidence of infection include Acrocanthosaurus, Allosaurus, Tyrannosaurus and a tyrannosaur from the Kirtland Formation . The infections from both tyrannosaurs were received by being bitten during a fight, like the Herrerasaurus specimen . </P> <P> A 2006 Space Shuttle experiment found that Salmonella typhimurium, a bacterium that can cause food poisoning, became more virulent when cultivated in space . On April 29, 2013, scientists in Rensselaer Polytechnic Institute, funded by NASA, reported that, during spaceflight on the International Space Station, microbes seem to adapt to the space environment in ways "not observed on Earth" and in ways that "can lead to increases in growth and virulence". More recently, in 2017, bacteria were found to be more resistant to antibiotics and to thrive in the near - weightlessness of space . Microorganisms have been observed to survive the vacuum of outer space . </P>

When do specific clinical signs and symptoms appear in the course of an infection