vaccination protects children from acquisition of infection with H. pylori), as of late 2019 there have been no advanced vaccine candidates and only one vaccine in a Phase I clinical trial. Furthermore, development of a vaccine against H. pylori has not been a current priority of major pharmaceutical companies.Many investigations have attempted to prevent the development of Helicobacter pylori-related diseases by eradicating the bacterium during the early stages of its infestation using antibiotic-based drug regimens. Studies find that such treatments, when effectively eradicating H. pylori from the stomach, reduce the inflammation and some of the histopathological abnormalities associated with the infestation. However studies disagree on the ability of these treatments to alleviate the more serious histopathological abnormalities in H. pylori infections, e.g. gastric atrophy and metaplasia, both of which are precursors to gastric adenocarcinoma. There is similar disagreement on the ability of antibiotic-based regiments to prevent gastric adenocarcinoma. A meta-analysis (i.e. a statistical analysis that combines the results of multiple randomized controlled trials) published in 2014 found that these regimens did not appear to prevent development of this adenocarcinoma. However, two subsequent prospective cohort studies conducted on high-risk individuals in China and Taiwan found that eradication of the bacterium produced a significant decrease in the number of individuals developing the disease. These results agreed with a retrospective cohort study done in Japan and published in 2016 as well as a meta-analysis, also published in 2016, of 24 studies conducted on individuals with varying levels of risk for developing the disease.
Asperger was investigating Asperger syndrome which, for various reasons, was not widely considered a separate diagnosis until 1981, although both are now considered part of ASD. Leo Kanner of the Johns Hopkins Hospital first used autism  in English to refer to classic autism when he introduced the label early infantile autism in a 1943 report. Almost all the characteristics described in Kanners first paper on the subject, notably "autistic aloneness" and "insistence on sameness", are still regarded as typical of the autistic spectrum of disorders. Starting in the late 1960s, classic autism was established as a separate syndrome.It took until 1980 for the DSM-III to differentiate autism from childhood schizophrenia. In 1987, the DSM-III-R provided a checklist for diagnosing autism. In May 2013, the DSM-5 was released, updating the classification for pervasive developmental disorders. The grouping of disorders, including PDD-NOS, autism, Asperger syndrome, Rett syndrome, and CDD, has been removed and replaced with the general term of Autism Spectrum Disorder. References


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