Currently, the term HIT is used without a modifier to describe the immune-mediated severe form.In 2021 a condition resembling HIT but without heparin exposure was described to explain unusual post-vaccination embolic and thrombotic events after the Oxford–AstraZeneca COVID-19 vaccine. It is a rare adverse event (1:1 million to 1:100,000) resulting from COVID-19 vaccines (particularly adenoviral vector vaccines). This is also known as Thrombosis with Thrombocytopenia Syndrome or TTS. References


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In the ten states where Lyme disease is most common, the average was 31.6 cases for every 100,000 persons for the year 2005.Although Lyme disease has been reported in all states about 99% of all reported cases are confined to just five geographic areas (New England, Mid-Atlantic, East-North Central, South Atlantic, and West North-Central). New 2011 CDC Lyme case definition guidelines are used to determine confirmed CDC surveillance cases.Effective January 2008, the CDC gives equal weight to laboratory evidence from 1 a positive culture for B. burgdorferi; 2) two-tier testing (ELISA screening and Western blot confirming); or 3) single-tier IgG (old infection) Western blot. Previously, the CDC only included laboratory evidence based on (1) and (2) in their surveillance case definition. The case definition now includes the use of Western blot without prior ELISA screen.The number of reported cases of the disease has been increasing, as are endemic regions in North America. For example, B. burgdorferi sensu lato was previously thought to be hindered in its ability to be maintained in an enzootic cycle in California, because it was assumed the large lizard population would dilute the number of people affected by B. burgdorferi in local tick populations; this has since been brought into question, as some evidence has suggested lizards can become infected.Except for one study in Europe, much of the data implicating lizards is based on DNA detection of the spirochete and has not demonstrated that lizards are able to infect ticks feeding upon them.