The concept that disease rooted principally in chronic aberrant constitutive and reactive activation of mast cells (MCs), without the gross MC neoplasia in mastocytosis, first emerged in the 1980s, but only in the last decade has recognition of “mast cell activation syndrome” (MCAS) grown significantly. Two principal proposals for diagnostic criteria have emerged. One, originally published in 2012, is labeled by its authors as a “consensus” (re-termed here as “consensus-1”). Another sizable contingent of investigators and practitioners favor a different approach (originally published in 2011, newly termed here as “consensus-2”), resembling “consensus-1” in some respects but differing in others, leading to substantial differences between these proposals in the numbers of patients qualifying for diagnosis (and thus treatment). Overdiagnosis by “consensus-2” criteria has potential to be problematic, but underdiagnosis by “consensus-1” criteria seems the far larger problem given (1) increasing appreciation that MCAS is prevalent (up to 17% of the general population), and (2) most MCAS patients, regardless of illness duration prior to diagnosis, can eventually identify treatment yielding sustained improvement. We analyze these proposals (and others) and suggest that, until careful research provides more definitive answers, diagnosis by either proposal is valid, reasonable, and helpful.

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While the number of deaths and hospitalizations caused by the novel coronavirus SARS-CoV-2 and the disease it causes (COVID-19) have captured public attention, a wave of chronic disease is also resulting from the pandemic. Some survivors of COVID-19, even those whose symptoms were too mild to warrant hospitalization, have struggled with persistent symptoms months after initial infection. SARS-CoV-2 affects several body systems and generates a wide variety of symptoms including dyspnea, myalgia, fatigue, and brain fog. It is yet unknown who is at risk of long-term disease, how long these symptoms may last, and what the long-term sequelae of the damage inflicted by this virus may be. NDs must adapt their practices to include consideration of COVID-19 as a differential diagnosis or root cause for a wide range of clinical presentations. The purpose of this article is to review the evidence of some of the longer-term effects and symptoms of COVID-19 that NDs may encounter in clinical practice, with background information on other post-infection syndromes for context.