Beta-hemolytic streptococci infection is the major contributing environmental factor. The typical route of infection is the upper respiratory system. Rarely it is also caused by a skin infection surrounding the anus (perianal streptococcal dermatitis). Diagnosis
Guttate psoriasis can typically be diagnosed by clinical examination alone. Management
The treatments used for plaque psoriasis can also be used for guttate psoriasis. Few studies have specifically focused on guttate psoriasis management, so there are currently no firm guidelines for managing guttate psoriasis differently from plaque psoriasis. Immunosuppressive drugs that inhibit T cell activation have been effective in treating severe cases of chronic guttate psoriasis. Due to the role streptococcal infection plays in the development of guttate psoriasis, systemic antibiotics have been considered as a potential treatment option. There is uncertain evidence whether systemic antibiotics or tonsillectomy are effective and safe in treating the disease. The condition often clears up on its own within weeks to months, and only about one third of patients will develop chronic plaques. Epidemiology
Guttate psoriasis accounts for approximately 2% of psoriasis cases. References


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In 1957 Black-Schaffer proposed a unitary explanation that stress on the ventricle, of any kind, may trigger the endocardial reaction, so that all EFE could be thought of as secondary.Evidence gradually accumulated as to the role of infection as one such type of stress. The studies of Fruhling and colleagues in 1962 were critical. They followed a series of epidemics of Coxsackie virus infection in their part of France. After each epidemic there were increased numbers of cases with EFE coming to autopsy. On closer study there were cases of pure acute myocarditis, cases of mixed myocarditis and EFE, and cases where myocarditis had healed, leaving just EFE. They were able to culture Coxsackie virus from the tissues of many of the cases at all stages  of this apparent progression. A similar progression from myocarditis to EFE was later observed at Johns Hopkins but no virology was done.Noren and colleagues at the University of Minnesota, acting on an idea floated at a pediatric meeting, were able to show a relation between exposure to maternal mumps in fetal life, EFE, and a positive skin test for mumps in infants. This brought on a large ongoing controversy and finally prompted a virologist colleague of theirs to inject embryonated eggs with mumps virus. The chicks at first showed the changes of myocarditis, about a year later, typical EFE, and transitional changes in between. Despite this, the controversy about the role of mumps continued as the actual incidence of EFE plummeted.