the infectious agent that causes aids is virus.
the infectious agent that causes aids is virus.
the infectious agent that causes aids is a(n)?
virus
the current consensus is that hiv was introduced to north america by a haitian immigrant who contracted it while working in the democratic republic of the congo in the early 1960s, or from another person who worked there during that time. in 1981 on june 5, the u.s. centers for disease control and prevention (cdc) published a "morbidity and mortality weekly report" (mmwr) describing cases of a rare lung infection, pneumocystis carinii pneumonia (pcp), in five healthy gay men in los angeles. this edition would later become "mmwr's" first official reporting of the aids epidemic in north america. by year-end, a cumulative total of 337 cases of severe immune deficiency had been reported, and 130 out of the 337 reported cases had died. on september 24 in 1982, the cdc used the term “aids” (acquired immune deficiency syndrome) for the first time, and released the first case definition of aids: “a disease at least moderately predictive of a defect in cell-mediated immunity, occurring in a person with no known case for diminished resistance to that disease.” the march 4, 1983 edition of the "morbidity and mortality weekly report" (mmwr) noted that most cases of aids had been reported among homosexual men with multiple sexual partners, injection drug users, haitians, and hemophiliacs. the report suggested that aids may be caused by an infectious agent that is transmitted sexually or through exposure to blood or blood products, and issued recommendations for preventing transmission. although most cases of hiv/aids were discovered in gay men, on january 7, 1983 the cdc reported cases of aids in female sexual partners of males with aids. in 1984, scientists identified the virus that causes aids, which was first named after the t-cells affected by the strain and is now called hiv or human immunodeficiency virus.
misconceptions about hiv/aids
in the 1950's, carleton gajdusek began research which eventually showed that kuru could be transmitted to chimpanzees by what was possibly a new infectious agent, work for which he eventually won the 1976 nobel prize. during the 1960s, two london-based researchers, radiation biologist tikvah alper and biophysicist john stanley griffith, developed the hypothesis that the transmissible spongiform encephalopathies are caused by an infectious agent consisting solely of proteins. earlier investigations by e.j. field into scrapie and kuru had found evidence for the transfer of pathologically inert polysaccharides that only become infectious post-transfer, in the new host. alper and griffith wanted to account for the discovery that the mysterious infectious agent causing the diseases scrapie and creutzfeldt–jakob disease resisted ionizing radiation. (a single ionizing "hit" normally destroys an entire infectious particle, and the dose needed to hit half the particles depends on the size of the particles. empirical results of ionizing doses applied to the unknown infectious substance evidenced an infectious particle size too small to be a viral mechanism.) in his paper, entitled "self-replication and scrapie", griffith proposed three ways in which a protein could be a pathogen. in the first hypothesis, he suggested that if the protein is the product of a normally suppressed gene, and introducing the protein could induce the gene's expression, that is, wake the dormant gene up, then the result would be a process indistinguishable from replication, as the gene's expression would produce the protein, which would then go wake the gene up in other cells. his second hypothesis forms the basis of the modern prion theory, and proposed that an abnormal form of a cellular protein can convert normal proteins of the same type into its abnormal form, thus leading to replication. his third hypothesis proposed that the agent could be an antibody if the antibody was its own target antigen, as such an antibody would result in more and more antibody being produced against itself. however, griffith acknowledged that this third hypothesis was unlikely to be true due to the lack of a detectable immune response.
prion