Bioterrorism Agents And Barrier Protection

Hemorrhagic Fever Viruses DEFINITION Viral hemorrhagic fevers (VHFs) refer to a group of illnesses that are caused by several distinct families of viruses. Each disease causes a febrile syndrome characterized by hemorrhagic complications, but mortality rates, incubation periods, and susceptibility to antiviral therapy vary depending on the etiologic agent. While some types of hemorrhagic fever can cause relatively mild illnesses, many of these viruses cause severe, life-threatening disease. These organisms pose a biological threat due to their potential to cause severe morbidity, and because transmission can occur from person to person.13,14 The viruses that are considered the most dangerous, if weaponized, include the filoviruses (Ebola and Marburg), arenaviruses (Lassa fever, Junin, Machupo, Guanarito, Sabia), flaviviruses (Omsk hemorrhagic fever, Kyasanur Forest disease), and bunyaviruses (Rift Valley fever). DIAGNOSIS Patients presenting with a fever greater than 101° Fahrenheit with at least two accompanying symptoms would be suspect. Notification of the local health department is necessary. For decisions regarding obtaining and processing diagnostic specimens, contact local, state, and regional laboratory authorities or the CDC. TREATMENT Patients receive supportive therapy because there is no established cure for VHFs. Ribavirin, an antiviral drug, has been effective in treating some individuals with Lassa fever. Treatment with convalescentphase plasma has been used with success in some patients. POST-EXPOSURE PROPHYLAXIS There is no post-exposure prophylaxis currently available for VHFs.13 There is currently no vaccine for VHFs. Clinical manifestations of VHF4 VHF Incubation Early Signs/Symptoms Later Signs/Symptoms Ebola virus 2-21 days. Fever, severe fatigue headache, myalgias, abdominal pain, diarrhea, may include chest pain, cough, pharyngitis, lymphadenopathy photophobia, conjunctival infection. Maculopapular rash predominantly on trunk, appearing about 5 days after onset of illness, jaundice, and pancreatitis often occur. As disease progresses, bleeding may develop, such as mucous membrane hemorrhages, hematemesis, bloody diarrhea, petechiae, ecchymoses. Marburg virus 2-14 days. Fever, exhaustion, headache, vomiting, conjuncitvitis, enanthem on soft palate, myalgias backache, clouded consciousness. Maculopapular rash appearing on 5th to 7th day on trunk, face, neck, and proximal regions of extremities, nonpruritic. Jaundice and pancreatitis. As disease progresses bleeding develops. Lassa fever 5-16 days. Gradual development of fever, weakness, malaise. Arthralgias, back pain, nonproductive cough by 3rd day, then severe exudative pharyngitis, maculopapular rash may be seen on fair skinned patients, severe exhaustion by 8th day. As disease progresses bleeding develops. Rift Valley fever 2-6 days. Fever headache, photophobia, and retro-orbital pain. Hepatitis, bleeding, encephalitis, retinitis. Kyasanur Forest disease 2-9 days. Sudden onset of fever, myalgias, headache. Vomiting and diarrhea. Enanthem with papulovesicular lesions on soft palate. Conjunctival congestion, subconjunctival hemorrhage, mild iritis, retinal and vitreous hemorrhage. cervical and axilary lymphadenopathy, bleeding from nose, gums, GI tract. Omsk hemorrhagic fever 2-9 days. Fever, headache, vomiting, enanthem on palate, hyperemia of skin on upper body & mucous membranes. Sever fever, generalized lymphadenopathy, splenomegaly and pneumonia. New World aarenaviruses, (Machupo, Junin, Guanarito, Sabia) 7-16 days. Gradual onset of fever, sore throat, myalgias, low back pain, abdominal pain. Vascular, neurologic manifestations may occur 5-7 days after illness onset, bleeding. INFECTION CONTROL Appropriate isolation precautions for patients with suspected or confirmed VHF include a combination of Airborne, Contact, Droplet, and Standard Precautions. Although airborne transmission of these agents appears to be rare, airborne transmission theoretically may occur; therefore, airborne precautions should be instituted for all patients with suspected VHF. Airborne Precautions Place the patient in a private room with negative air-pressure ventilation. Use external air exhaust or high-efficiency particulate air filters if the air is recirculated. Keep the door to the room closed. N-95 respirator. Contact Precautions Place patient in a private room. Gloves should be worn when entering the room and removed before leaving the room. Hands should be washed with an antimicrobial agent or a waterless handwashing agent immediately after removing gloves. Gowns should be worn when entering the room if it is anticipated that clothing will have contact with the patient, environmental surfaces, or items in the room. The gown should be removed before leaving the patient’s room. Patient transport should be limited to essential purposes only. Noncritical patient-care equipment should be dedicated whenever possible. Droplet Precautions Place the patient in a private room or in a room with other patients who have the same infection. When a private room and like infection patients are unavailable, spatial separation of a least three feet should be maintained. Healthcare workers should wear a standard surgical mask when working within three feet of the patient. Standard Precautions Handwashing Wash hands immediately after gloves are removed, between patient contacts, and when otherwise indicated to avoid transfer of microorganisms to other patients or environments. Gloves Wear gloves when touching blood, bodily fluid, secretions, excretions, and contaminated items; put on clean gloves just before touching mucous membranes and nonintact skin. Change gloves between tasks and procedures on the same patient after contact with material that may contain a high concentration of microorganisms. Remove gloves promptly after use, before touching noncontaminated items and environmental surfaces, and before going to another patient.Wash hands immediately to avoid transfer of microorganisms to other patients or environments. Masks, eye protection, face shields Wear a standard surgical mask and eye protection or a face shield to protect mucous membranes of the eyes, nose, and mouth during procedures and activities that are likely to generate splashes or sprays. Place all persons who have had close or high-risk contact with a patient suspected of having VHF during the 21 days following onset of symptoms under medical surveillance. If multiple patients with suspected VHF are admitted to one healthcare facility, group them in the same part of the hospital to minimize exposure to other patients and healthcare workers.

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