Editing Group A streptococcal infection (section)

== Epidemiology ==
Cases of GAS are still present today, but were also evident before World War I. This was shown by a training camp located in Texas, where a harmful strain of pneumonia complicating measles was caused by a strain of Streptococcus.<ref name=":02">{{Citation|last=Quinn|first=Robert W.|chapter=Streptococcal Infections|date=1982|pages=525–552|publisher=Springer US|isbn=9781475711424|doi=10.1007/978-1-4757-1140-0_29|title=Bacterial Infections of Humans}}</ref>  Existence of streptococci strains was additionally found in World War II. An epidemic of streptococcal infection in the United States Navy during this war indicated that this type of disease was able to exist and spread in formerly unexposed individuals by environments that [[Serology|serological]] types of group A streptococci preferred.<ref name=":02" /> In later years, a positive test result for the presence of group A streptococci was found in 32.1 percent of individuals after [[throat culture]]s were carried out in a 20-year-long (1953/1954–1973/1974) study performed in Nashville, Tennessee.<ref name=":02" /> Also, from 1972 to 1974, recurring GAS illness was observed with a prevalence of 19 percent in school-aged children as well as a prevalence rate of 25 percent in families.<ref name=":02" /> The severity of streptococcal infections has decreased over the years, and so has rheumatic fever (a [[sequela]]e of GAS) which is indicated by the change in numerous hospitals from containing wards allocated for the sole purpose of treating rheumatic fever to hardly seeing the disease at all.<ref name=":02" /> Environmental factors, such as less crowding and the increase of family living space, can account for the reduction in incidence and severity of group A streptococci.<ref name=":02" /> With more space for individuals to reside in, it provides the bacteria with less opportunities to spread from person to person. This is especially important considering an estimated 500,000 deaths worldwide all occurring after acute rheumatic fever, invasive infection, or subsequent heart disease can be accredited to GAS.<ref name=":12">{{Cite journal|last1=O'Loughlin|first1=R. E.|last2=Roberson|first2=A.|last3=Cieslak|first3=P. R.|last4=Lynfield|first4=R.|last5=Gershman|first5=K.|last6=Craig|first6=A.|last7=Albanese|first7=B. A.|last8=Farley|first8=M. M.|last9=Barrett|first9=N. L.|last10=Spina|first10=N. L.|last11=Beall|first11=B.|date=2007-10-01|title=The Epidemiology of Invasive Group A Streptococcal Infection and Potential Vaccine Implications: United States, 2000-2004|journal=Clinical Infectious Diseases|volume=45|issue=7|pages=853–862|doi=10.1086/521264|pmid=17806049|issn=1058-4838|doi-access=}}</ref> This number is quite large, often leaving the health care system encumbered, since 91 percent of patients infected with invasive GAS need to be hospitalized with 8950–11,500 episodes and 1050–1850 deaths taking place each year.<ref name=":12" /> A later study that occurred from 2005 to 2012 found that there were 10,649–13,434 cases consequently resulting in 1136–1607 deaths per year.<ref name=":22"/>