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Virology Review 2020

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Virology Review 2020 by Dr. Margie Morgan (MicrobeswithMorgan)

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Virology Review 2020

  1. 1. Margie Morgan, PhD, MT(ASCP), D(ABMM)
  2. 2. 1. Direct Staining specimen for Antigen 2. Enzyme Immunoassay 3. Viral Cell Culture 4. Molecular Amplification
  3. 3.  Direct Fluorescent antibody (DFA) stain  Collect cells from base of fresh vesicular lesion  Stain cells with antibody specific for HSV 1 and 2 and/or VZV  Look for fluorescent cells (virus infected) using fluorescence microscope  Sensitivity @ 80% for HSV 1, HSV 2, and VZV  Tzanck prep = Giemsa stained cells from lesion /examine for multinucleated giant cells consistent with Herpes virus family  Sensitivity @ 50% / Cannot differentiate HSV 1, HSV 2, or VZV Tzanck Tzanck DFA
  4. 4. • Enzyme immunoassay (EIA) –  Antigen in specimen forms a complex with test antibody – color producing substrate then binds to Ag/Aby complex  Rapid point of care (20 min) , moderate sensitivity (70%), specificity adequate with high prevalence during specific viral season  Used most often for:  Detection of non culturable viruses such as Rotavirus in stool specimens  Influenza A /B , & Respiratory syncytial virus (RSV) in respiratory specimens • Membrane lateral flow EIA Liquid/in-well EIA
  5. 5. • Inner wall of tube/vessel coated with monolayer of cells in enriched liquid growth media • Three types of cell lines:  Primary cell lines – direct from animal or human organ into culture tube , will only survive one subculture into a new culture vial  Example: Rhesus monkey kidney-RMK  Diploid – semi continuous cell lines– Can survive 20 – 50 subcultures into new culture vials –  Example: Human diploid fibroblast cells such as MRC-5-Microbiology Research Council 5  Continuous cell lines – survive continuous passage into new vials,  Example: Tumor lineages such as HEp-2 and HeLa
  6. 6.  Patient specimens inoculated onto cell cultures, incubated for a number of days, then read under light microscopy for “Cytopathic effect” – the effect viral growth has on the cell line • The pattern of destruction of the cell monolayer is specific for each virus type and the time in which destruction occurs is virus specific.
  7. 7. Spin Down Shell Vial Culture – • Technique created to speed up viral cell culture • Cell monolayer is created on a coverslip • Specimen inoculated into vial with coverslip and media • Centrifuge vial to induce (speed up) virus invasion of cells • Incubate @ 35C, 24-72 hours • Direct fluorescent antibody staining using early virus antigens (those first formed ) Cover slip
  8. 8.  Molecular Amplification of DNA or RNA (Qualitative) • Rapid/Sensitive/Specific detection method for numerous viruses • Direct amplification of DNA • RNA viruses - RT-PCR – reverse transcriptase enzyme transcribes complimentary copies of DNA using the RNA template • More rapid and exceeds sensitivity of viral culture. Has become the Standard of Practice for detection of many viruses:  Respiratory viruses  Encephalitis viruses  Lesion viruses • Tests of diagnosis not cure – can continue to shed residual virus for 7 – 30 days after initial positive test  Molecular quantitative assays  CMV, Hepatitis B and C and HIV
  9. 9.  Viral transport media (VTM) or Universal transport media (UTM) - Hanks balanced salt solution with antibiotics, human cell protects virus viability, antibiotics prevent bacterial overgrowth • Transport of lesions, mucous membranes, nasal & throat any specimens that are collected with swab  Short term transport storage 4˚C  Long term transport(>72hours) storage at -70˚C  VTM specimens filtered (45nm filter) to eliminate bacteria in specimen prior to being placed onto cell monolayer
  10. 10.  Double stranded DNA virus  Eight human Herpes viruses • Herpes simplex 1 • Herpes simplex 2 • Varicella Zoster • Epstein Barr • Cytomegalovirus • Human Herpes 6, 7, and 8  Latency (hallmark of Herpes viruses) occurs within small numbers of specific kinds of cells, the cell type is different for each Herpes virus
  11. 11.  Transmission: direct contact/secretions  Latency: dorsal root ganglia  Infection sites: • Gingivostomatitis most common primary infection • Herpes labialis • Ocular • Encephalitis • Neonatal – viral surface cultures should be performed for diagnosis • Disseminated in immune suppressed Therapy – Acyclovir, Valacyclovir
  12. 12.  Viral Cell Culture • Produce CPE within 24-48 hrs • Human diploid fibroblast (MRC-5) • Observe for characteristic CPE Negative fibroblast Cell line HSV CPE – cell rounding starting on the edge of the monolayer. Histology/Cytology – Observe for multinucleated giant cells, cannot differentiate HSV 1, 2 and VZV Molecular Amplification is standard of practice for detecting HSV 1 and 2 from lesions and CSF Serology – used to screen for past infection not current
  13. 13.  Transmission: close contact  Latency: dorsal root ganglia  Diseases: • Chickenpox (varicella) • Shingles (zoster – latent infection) More serious disease in adults and immune suppressed with possible progression to pneumonia and/or encephalitis Ramsay-Hunt syndrome – facial nerve / facial paralysis
  14. 14.  Histology – multi-nucleated giant cells  Serology useful for immune status check  Cell culture – growth 5-7 days, fibroblasts Sandpaper like appearance in cell monolayer with rounded cells  Molecular Amplification for disease diagnosis  Effective vaccine has lowered the incidence of VZV in children and incidence of shingles in adults
  15. 15.  Transmitted by blood transfusion , vertical and horizontal transmission to fetus, close human contact and sexual contact  Latency: Macrophages  Disease: • Initial infection asymptomatic in most • Congenital – most common cause of TORCH • Perinatal
  16. 16. Mononucleosis – Fever, no swollen lymph nodes, heterophile antibody negative Organ specific diseases: • Gastrointestinal • Hepatic • Neurological • Cardiovascular Primary infection in the immune suppressed host is more serious than recurrent or secondary infection
  17. 17.  Laboratory Diagnosis: • Cell culture  Human diploid fibroblast cell culture of choice  Cytopathic effect can take >=14 days • Quantitative PCR is most useful  Due to persistent CMV shedding - quantitative PCR used to detect significant viral loads, most consistent with ongoing infection • Histopathology – Infects epithelial cells, macrophages and T lymphocytes. Intranuclear and intracytoplasmic inclusions (Owl eye)  Treatment: ganciclovir, foscarnet, cidofovir
  18. 18.  Transmission - close contact, through saliva  Latency in the B lymphocyte • Cell receptor for EBV infection CD21  Diseases include: • Infectious mononucleosis  Heterophile antibody produced  Patient serum reacts with horse and cattle rbcs • Lymphoreticular disease • Oral hairy leukoplakia • Burkitt’s lymphoma • Nasopharyngeal Carcinoma • 1/3 Hodgkin’s lymphoma  Will not grow in usual viral cell culture  Molecular testing and /or serology for diagnosis EBV infection with B cell transformation
  19. 19. VCA IgM VCA IgG EBNA-1 IgG (EBV Nuclear antigen) Negative Negative Negative No immunity Positive Negative Negative Acute infection Positive Positive Negative Acute infection Negative Positive Positive Past infection Negative Positive Negative Acute or past infection Positive Positive Positive Late primary infection Negative Negative Positive Past infection VCA = viral capsid antibody Serologic Diagnosis of EBV
  20. 20. HHV-6 • Children  Roseola [sixth disease] usual age 6m-2yr, high fever & rash • Adult  In Immune compromised can cause encephalitis  Can undergo germ line integration and be a source of false positive results in the normal host HHV-8 • (1) Kaposi’s sarcoma
  21. 21. Castleman disease Primary effusion lymphoma • Seen most often in HIV/AIDS
  22. 22. Adenovirus
  23. 23.  DNA - non enveloped/ icosahedral virus  Latent: lymphoid tissue  Transmission: Respiratory and fecal-oral route  Diseases: • Pharyngitis (year round epidemics) • Pneumonia • Gastroenteritis in children  Adenovirus types 40 & 41 • Kerato-conjunctivitis – usually bilateral red painful and inflamed eyes for @ 2 weeks • Disseminated infection in immunosuppressed – often starting with pneumoniae, @ 75% fatality • Hemorrhagic cystitis in immune suppressed/ transplantation
  24. 24. Diagnosis • Cell culture (CPE) possible, <=5 days • Amplification (PCR)* superior • Stool antigen detection by EIA (40/41 strains) • Supportive treatment only – no specific viral therapy • Histology - Intranuclear inclusions / smudge cells – membranes become blurred Round cells 2 – 5 days with stranding – HeLA or Hep-2 culture cells
  25. 25. Parvovirus Parvovirus can infect many animal species but the B19 virus causes disease only in humans. Animals are not a source of infection for humans and vice versa.
  26. 26.  DNA virus - infects humans only  Parvovirus B19 infections • Erythema infectiosum (Fifth disease) – headache rash and cold-like symptoms in the child • Hydrops fetalis - in pregnant, infection in 1st trimester, leading to miscarriage • Aplastic crisis in patients with pre-existing bone marrow stress • Chronic hemolytic anemia HIV/AIDS • Arthritis and Arthralgia  Histology - virus infects mitotically active erythroid precursor cells in bone marrow • Molecular and Serologic methods to confirm diagnosis Slapped face appearance of fifth disease
  27. 27. Papillomavirus Polyomavirus – widely present and latent in the normal host, can become active CNS disease in the immune suppressed
  28. 28.  Diseases:  Skin and anogenital warts,  Benign head and neck tumors,  Cervical and anal intraepithelial neoplasia and cancer  HPV types 16, 18, High risk strains, cause @ 70% of cervical cancers.  Other high risk strains include: 31, 33, 45, 53, 58  HPV types 6 and 11 = Low risk strains cause @ 90% Genital warts  Diagnosis :  Pap Smear  PCR – Detection with typing of many HPV types  Guidelines suggest both PAP and HPV PCR for women 30 - 65 years of age / every 5 years  Vaccines - 1°to guard against HPV 6,11,16,18 for young females and males Pap smear
  29. 29. • JC virus - PML  Progressive multifocal leukoencephalopathy  Encephalitis of immune suppressed  AIDS, cancer and immune suppression  Destroys oligodendrocytes in brain • BK virus - Nephropathy  Latent virus infection in kidney  Progression due in immune suppression  Hemorrhagic cystitis • Diagnosis  Histology/ homogenous and purple intranuclear  inclusions, primarily in tubular epithelium Giant Glial Cells of JCV Demyelination is classic finding on MRI in JCV
  30. 30. Hepatitis B
  31. 31.  Enveloped DNA virus  Child can acquire from mother during birthing process  Spread by contact with blood and other body fluids  Spectrum of Hepatitis B symptomatology • Acute phase - disease varies from subclinical hepatitis to icteric hepatitis fulminant, acute, and subacute hepatitis • Chronic phase - chronic hepatitis, cirrhosis, and hepatocellular carcinoma (HCC)  Vaccinate to prevent  Therapies available to treat  Diagnosis • Molecular assays and Serology
  32. 32.  Surface Antigen Positive Detected • Patient has Active Hepatitis B or is a Chronic Carrier  Next perform Hep B Quantitation for to assess viral load  Perform Hep e antigen test – if positive, patient is a Chronic carrier and has a worse prognosis  Core Antibody Positive detected • Immune due to prior infection, acute infection or chronic carrier Surface Antibody Positive detected • Immune due to prior infection or vaccine
  33. 33. Hepatitis C Mosquito borne Flaviviridae: Dengue Zika Yellow fever West Nile Tick borne Flaviviridae Powassan fever
  34. 34.  Disease acquisition: Parenteral transmission, drug abuse, blood products or organ transplants (prior to 1992), poorly sterilized medical equipment, sexual  Infects humans and chimpanzees  Approx 3.2 mil persons in US have/had chronic HepC  Seven major genotypes (1-7) • Acute self limited disease that progresses to a disease that mainly affects the liver • Type 1 virus most common in USA • Infection persists in @ 75-85% without symptoms • 5 - 20 % develop cirrhosis • 1-5 % associated with hepatocellular CA  Can lead to liver transplantation
  35. 35. Diagnosis: • Hepatitis C IgG antibody test  If Hep C antibody detected perform  RNA quantitative assay for viral load  Genotype of virus for proper therapy selection and duration  Assessment of liver disease progression - ? Cirrhosis for proper therapy  Therapy can not reverse cirrhosis  No vaccine available  Antivirals currently FDA cleared that can cure >= 85% of patients infected with Hepatitis C
  36. 36. • Dengue – also known as “break bone fever” • Vector: Aedes aegypti mosquito / found in Asia and the Pacific • Disease  Fever, rash, and severe joint pain  Small % progress to a hemorrhagic fever which can be fatal • Diagnosis usually Serology -IgM for acute infection  Zika virus • Vector: Aedes aegypti and A. albopictus mosquitoes • 2016 outbreak began in South America (Brazil) and spread to central America, Caribbean and US (Miami) • Clinically usually a milder disease than Dengue in most adults , fever and rash • Problem is the Neurologic tropism  Microcephaly in fetuses borne to infected moms  Potential developmental issues in infected children  Guillain-Barre syndrome • Diagnosis: Serum antibody IgM / PCR serum, urine, amniotic fluid and CSF
  37. 37. Yellow fever  Vector – Aedes aegypti mosquito  Most cases mild with 3-4 days fever, headache, chills, back pain, fatigue, nausea, vomiting • 15% cases toxic phase with jaundice due to liver damage, hemorrhagic issues, with 20 – 50% fatality rate  Diagnosis confirmed by molecular testing for virus in serum  Outbreaks possible when large numbers of infected mosquitoes are introduced into a heavily populated area,  Endemic in Africa, Central and South America • Large outbreak in Brazil 2018  No specific anti-viral drugs  Vaccine – supplies life long immunity
  38. 38. • West Nile  Vectors: Culex pipiens mosquito  Numerous Culex species can carry WN  Common across the US/ including CA  Birds primary reservoir, horses at risk  Disease  80% asymptomatic  20% Fever, Headache, Muscle weakness  Small % progress to encephalitis, meningitis, flaccid paralysis  Serology and Molecular assays  Molecular testing for West Nile has low sensitivity, and narrow time range for detection, both tests are necessary for high % diagnosis Cross reactions occur in serologic testing for the Flavivirus family: Dengue, Zika and West Nile virus, present diagnostic problems
  39. 39. Powassan (POW) virus  Transmitted to humans by Ixodes ticks  Approximately 100 cases of POW virus disease were reported in the United States over the past 10 years. • Most cases have occurred in the Northeast and Great Lakes region  Fever, headache, vomiting, weakness, confusion, seizures, and memory loss, can cause significant swelling in the brain  Long-term neurologic problems may occur.  There is no specific treatment
  40. 40.  Chikungunya virus  Vector Aedes mosquito including aegypti  Origin in Asia and African continents with recent migration to the Caribbean and SE USA  Acute febrile illness with rash followed by extreme joint pain,  No hemorrhagic phase  When screening for ZIKA – need to rule out infection with Dengue and Chikungunya. Similar diseases with very different sequelae
  41. 41.  >20 outbreaks since discovery in 1976 • Most recent problems started in Dec 2013 - West Africa • Prolonged outbreak due to area affected has high population with limited medical resources  Transmission direct contact with bodily fluids – fatality rate 55% • Animal reservoir (?) fruit bats  Asymptomatic not contagious  Fever, weakness, myalgia, headache, travel history • Also consider malaria and typhoid in the differential • Multifocal necrosis in liver, spleen, kidneys, testes and ovaries  Susceptible to hospital disinfectants  Testing (EIA, PCR) at CDC – positive >= 4 days of illness  Level A agent of Bioterrorism
  42. 42. SARS - Severe Acute Respiratory Syndrome –  Outbreak in China 2003 – spread to 29 countries  Dry cough and/or shortness of breath with development of pneumonia by day 7-10 of illness Lymphopenia in most cases  Laboratory testing public health laboratories (CDC) -antibody testing enzyme immunoassay (EIA) and molecular tests for NP, Throat, sputum, blood, and stool specimens. • MERS - Middle East Respiratory Syndrome • Arabian peninsula (2012) • Direct contact with infected camels • Close human to human contact can spread infection – no outbreaks – 30% fatality rate respiratory failure • Fever, rhinorrhea, cough, malaise followed by shortness of breath
  43. 43. SARS-CoV-2 is the name given this novel Coronavirus At the time of this lecture what is known • Of animal origin/most closely related to Bat Coronavirus • First infections related to exposure at open animal market in Wuhan, China • Influenza-like illness ranging from mild symptoms to severe respiratory illness and death (death rate 2 .5%), usually starts with:  Fever  Dry cough/ shortness of breath • Spread primarily by exposure to respiratory secretions
  44. 44.  Diverse group of > 60 viruses – SS RNA • Infections occur most often in summer and fall • Polio virus - paralysis  Salk vaccine Inactive Polio Vaccine (IPV)** recommended • Coxsackie A – Herpangina – vesicular oral lesions • Coxsackie B – Pericarditis/Myocarditis • Enterovirus – Aseptic meningitis in children, hemorrhagic conjunctivitis, Acute flaccid myelitis EV-D68 • Echovirus – various infections, intestine • Rhinoviruses – common cold  Grow in cell culture * 5-7 days • Teardrop or kite like cells formed  Molecular assays superior for diagnosis
  45. 45.  Fecal – oral transmission, contaminated food or person to person  Traveler’s disease  Recent outbreaks in homeless populations without adequate sanitary facilities  80% develop symptoms – jaundice & elevated aminotransferases  Usually – short incubation (15- 50 days), abrupt onset, low mortality, no carrier state  Diagnosis – serology, IgM positive in early infection to differ from other Hepatitis viruses  Antibody is protective and lasts for life  Vaccine available
  46. 46.  Hemagglutinin and Neuraminidase are glycoprotein spikes on outside of viral capsid • Gives Influenza A the H and N designations – such as H1N1 and H3N2  Antigenic drift - minor change in the amino acids of either the H or N glycoprotein  Cross antibody protection will still exist so an epidemic will not occur  Antigenic shift - genome re assortment with a “new” virus created/usually from a bird or animal/ this could create a potential pandemic  H5N1 = Avian Influenza  H1N1 = 2009 Influenza A
  47. 47.  Disease: fever, malaise …. Death from respiratory complications or secondary bacterial infection  Yearly H and N types dominate, most recently H1N1 and H3N2  Diagnosis • Cell culture obsolete [RMK] • Enzyme immunoassay (EIA) lateral flow membrane can be used in point of care testing • Amplification (PCR) gold standard for detection  Treatment: Amantadine and Tamiflu (Oseltamivir) • Seasonal variation in susceptibility but Tamiflu sensitive currently  Influenza B • Milder form of Influenza like illness • Usually <=10% of cases /year  Vaccinate – Quadrivalent vaccine – 2 A types, 2 B types
  48. 48.  Disease • Fever, Rash, Dry Cough, Runny Nose, Sore throat, inflamed eyes (photosensitive), Respiratory secretions very contagious • Koplik’s spot – small red spots with central bluish discoloration- inner lining of the cheek • Subacute sclerosing panencephalitis [SSPE]  Rare chronic degenerative neurological disease  Persistent infection with a mutated measles virus, due to mutated virus there is total lack of an immune response  Diagnosis: Clinical symptoms, PCR nasal or throat is best, IgM serology can have false positive reactions  Histology for acute lung injury – multinucleated giant cells, inclusions with perinuclear halos  Vaccinate – MMR (Measles, Mumps, Rubella) vaccine  Treatment: Not specific, Immune globulin, vitamin A H and E stain/ lung
  49. 49.  Types 1,2,3, and 4  Person to person spread  Disease: • Upper respiratory tract infection in adults and children with fever, runny nose and cough • Lower respiratory tract infection - Croup, bronchiolitis and pneumonia more likely in children, elderly and immune suppressed  Molecular** methods standard of practice  Supportive therapy only available  No vaccine
  50. 50. Person to person contact Leads to Parotitis, other sites affected less common: Testes/ovaries, Eye, Inner ear, CNS Diagnosis: clinical symptoms and serologic tests, and molecular assays Prevention: Measles/Mumps/Rubella (MMR) vaccine No specific therapy, supportive
  51. 51.  Respiratory disease - common cold to pneumonia, bronchiolitis to croup, serious disease in infants and immune suppressed • Classic disease: Young infant with bronchiolitis  Transmission by contact and respiratory droplet  Diagnosis: EIA (point of care), cell culture (heteroploid, continuous cell lines), Molecular testing is gold standard**, and lung biopsy  Treatment: Supportive, ribavirin Classic CPE = Syncytium formation heteroploid cell line Syncytium formation In lung tissue
  52. 52.  1st discovered in 2001 – community acquired respiratory tract disease in winter • 95% of cases in children <6 years of age but can be seen in the elderly and the immune suppressed • Upper respiratory tract disease • Lower respiratory tract disease  2nd only to RSV in the cause of bronchiolitis  Will not grow in cell culture  Molecular assays (PCR) for detection  Treatment: Supportive
  53. 53.  Winter - spring seasonality • Gastroenteritis with vomiting and fluid loss – most common cause of severe diarrhea in children 6m – 2 yrs • Fecal – oral spread  Major cause of childhood death in 3rd world countries  Diagnosis – cannot grow in cell culture • Enzyme immunoassay, PCR  Vaccine available Rota = Wheel EM Pix
  54. 54.  Spread by contaminated food and water, feces & vomitus – takes <=20 virus particles to spread infection – so highly contagious  Tagged the “Cruise line virus” – numerous reported food borne outbreaks aboard cruise liners  Leading cause of epidemic gastroenteritis – worldwide on land or sea • Fluid loss from vomiting can be debilitating especially children  Disease course usually limited, 24-48 hours  Molecular methods for diagnosis • Cannot be grown in cell culture
  55. 55.  CD4 primary receptor site for entry of HIV into the lymphocyte  Reverse transcriptase enzyme converts genomic RNA into DNA  Transmission - sexual, blood and blood product exposure, perinatal  Non infectious complications: • Lymphoma, KS, Anal cell CA, non Hodgkins Lymphoma  Infectious complications: • Pneumocystis, Cryptococcal meningitis, TB and Mycobacterium avium complex, Microsporidia, Cryptosporidium, STD’s , Hepatitis B and C
  56. 56. Antibody EIA with Western Blot confirmation (old way)  Positive EIA tests must be confirmed with a Western blot test  Western blot detects gp160/gp120 (envelope proteins), p 24 (core), and p41(reverse transcriptase)  Must have at least 2 solid bands on Western blot to confirm as a positive result New test - Antigen/antibody combination (4th generation) immunoassay* that detects IgG and IgM HIV-1 and HIV-2 antibodies and HIV-1 p24 antigen to screen for established and acute infection Detects infection earlier @ 2- 4 weeks Positive patients require additional testing:  HIV viral load quantitation >= 100 copies  Resistance Testing – report subtype to optimize therapy  Most isolates in USA type B • Monitor for low CD4 counts for infection severity
  57. 57. RNA Virus Rubella
  58. 58.  Known as the “Three day measles” or German measles  Relatively mild disease with rash, low grade fever, cervical lymphadenopathy  Respiratory transmission  Congenital rubella – • Occurs in a developing fetus of a pregnant women who has contracted Rubella, highest % (50%) in the first trimester of pregnancy • Prior to Zika it was the neurotropic virus of the fetus  Deafness, eye abnormalities, congenital heart disease  Diagnosis - Serology in combination with clinical symptoms  Live attenuated vaccine (MMR) to prevent
  59. 59. Hantavirus
  60. 60.  1993 - Outbreak on Indian reservation in the four corner states (NM,AZ,CO,UT) brought attention to this virus  Source - urine and secretions of wild deer mouse and cotton rat  Outbreak from transmission from pet rats to humans/ Yosemite National Park cabins  Myalgia, headache, cough and respiratory failure  Found in states west of the Mississippi River  Diagnosis by serology  Supportive therapy
  61. 61. Smallpox virus Variola virus Vaccinia virus
  62. 62.  Variola virus – agent of Smallpox, eradicated in 1977  Vaccinia virus - active constituent in the Smallpox vaccine, it is immunologically related to smallpox, • Vaccinia can cause disease in the immune suppressed, which prevents vaccination of this population to smallpox  Disease begins as maculopapular rash progresses to vesicular rash  All lesions in same stage of development in one body area – rash moves from central body outward  Category A Bioterrorism agent  Requires BSL4 laboratory (self contained lab)  Reported to public health department for investigation
  63. 63. Rabies virus
  64. 64.  Worldwide in animal populations • Bat and raccoons primary reservoir in US • Dogs in 3rd world countries • Bites and inhalation of aerosolized bat saliva, urine and feces  Post exposure rabies vaccine and rabies immunoglobulin PRIOR to the development of symptoms prevent disease  Classic disease symptom is salivation, due to paralysis of throat muscles  Detection of viral particles in the brain by Histologic staining known as Negri bodies and detection of rabies genetic material by molecular assays in saliva  Public health department should be contacted to assist with diagnosis Intracytoplasmi Negri bodies In brain biopsy
  65. 65.  Rare, degenerative fatal brain disorder  Transmissible spongiform encephalopathies (TSE) name established from the microscopic appearance of infected brain  Caused by type of protein known as prion  Confirmation by brain biopsy Spongiform change in the gray matter  Safety – prevent transmission • Universal Precautions • Use disposable equipment when possible Spongiform change in the Gray matter