Powassan virus (POWV) disease is a rare human disease caused by a tick-borne encephalitis group flavivirus maintained in a transmission cycle between Ixodes cookei and other ixodid ticks and small and medium-sized mammals. During 1958-1998, only 27 POWV disease cases (mostly Powassan encephalitis) were reported from eastern Canada and the northeastern United States (average, 0.7 cases per year). During 1999-2005, nine cases (described herein) of serologically confirmed POWV disease were reported in the United States (average, 1.3 cases per year): four from Maine, two from New York, and one each from Michigan, Vermont, and Wisconsin. The Michigan and Wisconsin cases are the first ever reported from the north-central United States. Of these nine patients, 5 (56%) were men, the median age was 69 years (range: 25-91 years), and 6 (67%) had onset during May-July. All but one patient developed encephalitis with acute onset of profound muscle weakness, confusion, and other severe neurologic signs. In one case, no neurologic symptoms were present but the presence of pleocytosis, an elevated cerebrospinal fluid (CSF) protein concentration, and POWV-specific immunoglobulin M in CSF suggested neuroinvasion. All patients recovered from their acute disease, but most had long-term neurologic sequelae. Periresidential ecologic investigations were performed in three cases, including tests of local mammals and ticks for evidence of POWV infection. Woodchucks (Marmota monax), striped skunks (Mephitis mephitis), and a raccoon (Procyon lotor) collected at two of the Maine case-patients' residences had neutralizing antibody titers to POWV. I. cookei were found on woodchucks and skunks and questing in grassy areas of one of these residences; all were negative for POWV. Although POWV disease is rare, it is probably under-recognized, and it causes significant morbidity, and thus is an additional tick-borne emerging infectious disease entity. Because no vaccine or specific therapy is available, the basis of prevention is personal protection from ticks (or "tick hygiene") and reduced exposure to peridomestic wild mammals.

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OBJECTIVES. This study describes causes of death in persons with acquired immunodeficiency syndrome (AIDS) and assesses the completeness of reporting of human immunodeficiency virus (HIV) infection or AIDS on death certificates of persons with AIDS. METHODS. AIDS case reports were linked with death certificates in 11 local/state health departments; underlying and associated causes of death were available for 32,513 persons with AIDS who died. RESULTS. HIV/AIDS was designated as the underlying cause of death for 46% of persons with AIDS who died between 1983 and 1986 and 81% of persons with AIDS who died since 1987 (the year specific coding procedures were implemented for HIV/AIDS). Most other underlying causes of death were conditions within the AIDS case definition (notably Pneumocystis carinii pneumonia), pneumonia, infections outside the AIDS case definition, and drug abuse. Unintentional injuries, suicide, and homicide were less common. HIV/AIDS was listed as underlying or associated on 88% of death certificates from 1987 to 1989; reporting varied primarily by HIV exposure category and time between diagnosis and death. CONCLUSIONS. Physicians and other health care professionals should realize their critical role in accurately documenting HIV-related mortality on death certificates. Such data can ultimately influence the allocation of health care resources for HIV-infected individuals.

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