Cathleen A. Hanlon, David R. ShlimI

Cathleen A. Hanlon, David R. Shlim

INFECTIOUS AGENT

Rabies is an acute, fatal, progressive encephalomyelitis caused by neurotropic viruses in the family Rhabdoviridae, genus Lyssavirus. Numerous and diverse variants of lyssaviruses are found throughout the world, all of which may cause fatal human rabies cases. Tens of millions of human exposures and tens of thousands of deaths may occur each year.

TRANSMISSION

The most natural and successful mode of transmission is through the bite of a rabid animal. Virus at the wound site may remain undetectable during a variable incubation period; there is no viremia. Clinical illness begins following invasion of the peripheral and then central nervous system and culminates in acute fatal encephalitis. Exposure of highly innervated tissue and close proximity to the brain increases the risk of successful infection and may result in postexposure prophylaxis (PEP) failure if there is a delay in administration. Rarely, virus has been transmitted by exposures other than bites, such as introducing the agent into open wounds (such as through scratches) or mucous membranes and transplantation of tissues from undiagnosed rabid donors.

All mammals are believed to be susceptible to infection, but major reservoirs are carnivores and bats. Although dogs are the main reservoir in developing countries, the epidemiology of the disease differs from one region or country to another, so that all patients with mammal bites should be medically evaluated. Bat bites anywhere in the world are a cause of concern and an indication to consider prophylaxis.

EPIDEMIOLOGY

Rabies is found on all continents, except Antarctica. Regionally, different viral variants are adapted to various mammalian hosts and perpetuate in dogs and wildlife, such as bats and some carnivores, including foxes, jackals, mongooses, raccoons, and skunks. In certain areas of the world, canine rabies remains enzootic, including parts of Africa, Asia, and Central and South America. Table 3-14 lists countries that have reported no cases of rabies during the most recent period for which information is available (formerly referred to as “rabies-free” countries).

Timely and specific information about the global occurrence of rabies is often difficult to find. Surveillance levels vary, and reporting status can change suddenly as a result of disease reintroduction or emergence. The rate of rabies exposures in travelers is at best an estimate and may range from 16 to 200 per 100,000 travelers.

CLINICAL PRESENTATION

After infection, the incubation period is variable, but clinical illness most commonly develops in several weeks to several months after exposure. The disease progresses rapidly from a nonspecific, prodromal phase with fever and vague symptoms to an acute, progressive encephalitis. The neurologic phase may be characterized by anxiety, paresis, paralysis, and other signs of encephalitis; spasms of swallowing muscles can be stimulated by the sight, sound, or perception of water (hydrophobia); and delirium and convulsions can develop, followed rapidly by coma and death. Once clinical signs manifest, patients die quickly, but with intensive supportive care may succumb in 7–14 days.

DIAGNOSIS

The diagnosis may be relatively simple in a patient with a compatible history and a classic clinical presentation. However, clinical suspicion and prioritization of differential diagnoses may be complicated by variations in clinical presentation and a lack of exposure history. The exposure history is especially evasive if the risk of exposure to rabies was not recognized, the exposure was not discussed with friends and family, and several weeks to months have elapsed since the exposure.

Definitive antemortem diagnosis requires high-complexity experimental test methods on multiple samples (such as serum, cerebrospinal fluid [CSF], saliva, and skin biopsy from the nape of the neck), which are best collected sequentially if initial testing is negative. Additional detailed information on diagnostic testing may be obtained from CDC (http://www.cdc.gov/rabies/specific_groups/doctors/ante_mortem.html). Rising levels of rabies virus–neutralizing antibodies, particularly in the CSF, is diagnostic in an unvaccinated, encephalitic patient.

Kết quả (Việt) 1:

Cathleen A. Hanlon, David R. ShlimCÁC ĐẠI LÝ TRUYỀN NHIỄMBệnh dại là một encephalomyelitis cấp tính, gây tử vong, tiến bộ, gây ra bởi virus neurotropic trong gia đình Rhabdoviridae, chi Lyssavirus. Rất nhiều và đa dạng các biến thể của lyssaviruses được tìm thấy trên khắp thế giới, tất cả đều có thể gây ra trường hợp tử vong của con người dại. Hàng chục triệu con người tiếp xúc và hàng chục ngàn người chết có thể xảy ra mỗi năm.BỘ TRUYỀN ĐỘNGChế độ tự nhiên và thành công nhất của truyền là thông qua các vết cắn của một con vật dư tợn. Virus tại chỗ vết thương có thể vẫn không thể phát hiện trong một thời gian ủ bệnh biến; có là không có viremia. Lâm sàng bệnh bắt đầu sau cuộc xâm lược của các thiết bị ngoại vi và sau đó hệ thống thần kinh trung ương và culminates trong viêm não cấp tính gây tử vong. Tiếp xúc với mô cao phân bố và gần đến não làm tăng nguy cơ nhiễm trùng thành công và có thể dẫn đến sản postexposure (PEP) thất bại nếu không có một sự chậm trễ trong chính quyền. Hiếm khi, virus đã được truyền qua tiếp xúc khác hơn so với cắn, chẳng hạn như giới thiệu các đại lý vào vết thương mở (chẳng hạn như thông qua các vết trầy xước) hoặc màng nhầy và cấy ghép mô từ các nhà tài trợ dư tợn chẩn đoán.All mammals are believed to be susceptible to infection, but major reservoirs are carnivores and bats. Although dogs are the main reservoir in developing countries, the epidemiology of the disease differs from one region or country to another, so that all patients with mammal bites should be medically evaluated. Bat bites anywhere in the world are a cause of concern and an indication to consider prophylaxis.EPIDEMIOLOGYRabies is found on all continents, except Antarctica. Regionally, different viral variants are adapted to various mammalian hosts and perpetuate in dogs and wildlife, such as bats and some carnivores, including foxes, jackals, mongooses, raccoons, and skunks. In certain areas of the world, canine rabies remains enzootic, including parts of Africa, Asia, and Central and South America. Table 3-14 lists countries that have reported no cases of rabies during the most recent period for which information is available (formerly referred to as “rabies-free” countries).Timely and specific information about the global occurrence of rabies is often difficult to find. Surveillance levels vary, and reporting status can change suddenly as a result of disease reintroduction or emergence. The rate of rabies exposures in travelers is at best an estimate and may range from 16 to 200 per 100,000 travelers.CLINICAL PRESENTATIONAfter infection, the incubation period is variable, but clinical illness most commonly develops in several weeks to several months after exposure. The disease progresses rapidly from a nonspecific, prodromal phase with fever and vague symptoms to an acute, progressive encephalitis. The neurologic phase may be characterized by anxiety, paresis, paralysis, and other signs of encephalitis; spasms of swallowing muscles can be stimulated by the sight, sound, or perception of water (hydrophobia); and delirium and convulsions can develop, followed rapidly by coma and death. Once clinical signs manifest, patients die quickly, but with intensive supportive care may succumb in 7–14 days.DIAGNOSISThe diagnosis may be relatively simple in a patient with a compatible history and a classic clinical presentation. However, clinical suspicion and prioritization of differential diagnoses may be complicated by variations in clinical presentation and a lack of exposure history. The exposure history is especially evasive if the risk of exposure to rabies was not recognized, the exposure was not discussed with friends and family, and several weeks to months have elapsed since the exposure.Definitive antemortem diagnosis requires high-complexity experimental test methods on multiple samples (such as serum, cerebrospinal fluid [CSF], saliva, and skin biopsy from the nape of the neck), which are best collected sequentially if initial testing is negative. Additional detailed information on diagnostic testing may be obtained from CDC (http://www.cdc.gov/rabies/specific_groups/doctors/ante_mortem.html). Rising levels of rabies virus–neutralizing antibodies, particularly in the CSF, is diagnostic in an unvaccinated, encephalitic patient.