Introduction History Epidemiology Current outbreak Mode of transmission Replication Pathogenesis Diagnosis Prevention Animal models

Transcription

1 Dr. Sonu kumari Agrawal PGIMER, CHANDIGARH Introduction History Epidemiology Current outbreak Mode of transmission Replication Pathogenesis Diagnosis Prevention Animal models 1

2 Ebola virus is pathogen of viral haemorrhagic fever causing severe disease and high case-fatality rates 2

3 Nearly 40 years ago Belgian scientist travelled to a remote part of the Congolese rainforest Unknown and terrifying disease September 1976 YAMBUKU Electron Microscope MARBURG VIRUS Institute of Tropical Medicine Antwerp 3

4 Group: Group ss RNA Order : Mononegavirales Family: Filoviridae Genus: Ebola virus 4

5 Shape of a shepherd's crook or in the shape of a " U" or a " 6" and they may be coiled or branched Linear non-segmented, single-stranded RNA Virus 80 nm in width, but vary some what in length Structure of Ebola genome and proteins - 7 structural and 1 nonstructural 7 structural proteins - Nucleoprotein (NP) 4 viral/virion proteins (VP35, VP40, VP30, VP24) Glycoprotein (GP) RNA-dependent RNA polymerase (L protein) 5

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7 Mortality rate ZEBOV 60-90% SEBOV 40-60% CIEBOV 0% BEBOV 20-30% 7

8 First cases of filovirus haemorrhagic fever Germany and the former Yugoslavia - Marburg virus In northern Zaire, now Democratic Republic of the Congo (DRC) EBOLA VIRUS 8

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10 Year Coutry Ebola Species Cases Death CFR 2005 Congo Zaire % 2007 DRC Zaire % 2007 Uganda Bundibugyo % 2008 DRC Zaire % 2011 Uganda Sudan % 2012 Uganda Sudan % 10

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12 Initial outbreak in Guinea 6 December Guéckédou, Guinea A 2-year-old boy died His mother 3 year-old sister Grandmother 35 cases killed 23 Funeral March - dozens of people were dead in eight Guinean villages Two people -carried the disease to their village 15 March 2014 WHO reported that the Ministry of Health of Guinea 86 suspected cases May,2014 Boffa, Télimélé, Boke and Dubrék 23 May 59 deaths 23 April, confirmed cases deaths Mid- Jun e 25 July 12

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14 8 August,

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16 What in the world is Zaire ebolavirus doing in West Africa, far from its usual haunts in Central Africa? why no Ebola virus has ever been seen before? before? Why now? Poor Economy To stay alive - to find wood to make charcoal and deeper into mines to extract minerals -Risk of exposure to Ebola virus Exposures related to Hunting and consumption of fruit bats Neglected health-care facility where a supply of gloves, clean needles, and no disinfectants 16

17 Bats are considered the most likely natural reservoir of the EBOV Bats were known to reside in the cotton factory in which the first cases for the 1976 and 1979 outbreaks were employed The absence of clinical signs in these bats is characteristic of a reservoir species 17

18 A wide range of hosts were infected with ebola bats They got infected, replicated virus, and survived infection Detect anti-ebola virus antibodies and Ebola virus RNA in fruit bat species 18

19 Could Zaire ebola virus have been recently introduced into Guinea from Central Africa? Introduction from a human traveler seems Unlikely 19

20 45,000 Indians in the affected countries At risk 20

21 On September 1, 1976, four days after returning from a tour of northern Zaire Health care worker Contacts & family member of the ebola virus the index case, a 44 year-old male teacher at the Mission School, sought medical intervention for a febrile illness he thought to be malaria parenteral injection of chloroquine (an anti-malaria drug) from Yambuku Mission Hospital (YMH) Mourners who have direct contact with bodies YMH did not use disposable needles or sterilize the needles Parenteral injection was the primary mode of administering nearly all medicines disseminated into the surrounding villages serviced by YMH 21

22 Not entirely clear how Ebola is spread Natural host of Ebola virus - Direct contact with blood or bodily fluids from an infected person fruit bats - species of the genera Hypsignathus monstrosus,epomopsfranqueti contact and with Myonycteris contaminated medical Bats drop partially torquata eaten equipment, particularly needles and fruits and pulp syringes No Airborne transmission Then land mammals such as gorillas,chimpanzees and duikers feed on these fallen fruits 10 % Health care worker affected 22

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25 Incubation period: 2-21 days Stage I (unspecific): Extreme asthenia (body weakness) Diarrhea, nausea and vomiting, anorexia Abdominal pain Headaches, arthralgia, myalgia,back pain Mucosal redness of the oral cavity, dysphagia, conjunctivitis Rash Stage II (Specific): Hemorrhage - Petechiae, ecchymoses, uncontrolled oozing from venepuncture sites, mucosal haemorrhages -30 to 40% Anuria, Tachypnea Late Complications: (>2 weeks after onset) Shock, convulsions Migratory arthralgias Ocular disease (unilateral vision loss, uveitis) Orchitis, suppurative parotitis Pericarditis Illness-induced abortion among pregnant women 25

26 Differential diagnosis 26

27 Clinical feature Laboratory Diagnosis 27

28 suspected - (alive or dead person with fever and at least three additional symptoms, or fever and a history of contact with a person with hemorrhagic fever or a dead or sick animal, or unexplained bleeding) Probable - meets the suspected case definition and has an epidemiologic link to a confirmed or probable case Confirmed - suspected or probable case that also has laboratory confirmation Category A Diseases/Agents Category B Diseases/Agents Category C Diseases/Agents High-priority agents include. organisms that pose a risk to national security because they can be easily disseminated or transmitted from person to person result in high mortality rates and have the potential for major public health impact might cause public panic and social disruption require special action for public health preparedness. Second highest priority agents include those that are moderately easy to disseminate; result in moderate morbidity rates and low mortality rates; and require specific enhancements of CDC's diagnostic capacity and enhanced disease surveillance Third highest priority agents include emerging pathogens that could be engineered for mass dissemination in the future because of availability; ease of production and dissemination; and potential for high morbidity and mortality rates and major health impact. 28

29 Category A Category B Category C Anthrax (Bacillus anthracis) Botulism (Clostridium botulinum toxin) Plague (Yersinia pestis) Smallpox (variola major) Tularemia (Francisella tularensis) Viral hemorrhagic fevers EBOLA VIRUS Marburg]and arenaviruses [e.g., Lassa, Machupo]) Brucellosis (Brucella species) Epsilon toxin of Clostridium perfringens Food safety threats (e.g., Salmonella species, Escherichia coli O157:H7, Shigella) Glanders (Burkholderia mallei) Melioidosis (Burkholderia pseudomallei) Psittacosis (Chlamydia psittaci) Q fever (Coxiella burnetii) Ricin toxin from Ricinus communis (castor beans) Staphylococcal enterotoxin B Typhus fever (Rickettsia prowazekii) Viral encephalitis (alphaviruses [e.g., Venezuelan equine encephalitis, eastern equine encephalitis, western equine encephalitis]) Water safety threats (e.g., Vibrio cholerae, Cryptosporidium parvum) Emerging infectious diseases such as Nipah virus and hantavirus Category Definitions Risk Group 4 pathogens Biosafety level -4 containment 29

30 Triple packaging using absorbent material With cold chain Institute Pasteur, the European Mobile Laboratory CDC in Guinea the Kenema Government Hospital Viral Hemorrhagic Fever Laboratory in Sierra Leone Liberia Institute of Biomedical Research 30

31 Sample Timeline of Infection Within a few days after symptoms begin Diagnostic tests available Antigen-capture enzyme-linked immunosorbent assay (ELISA) testing IgM ELISA Polymerase chain reaction (PCR) Virus isolation Later in disease course or after recovery Retrospectively in deceased patients IgM and IgG antibodies Immunohistochemistry testing PCR Virus isolation 31

32 Serology IgM anti-bodies can appear as early as two days post onset of symptoms and disappear between 30 and 168 days after infection IgG-specific antibodies develop between day 6 and 18 after onset and persist for many years 32

33 v Virus isolation 33

34 Cell line VeroE6 and MA104 Cells were observed for cytopathic effect for 2 weeks Causes lytic infections in cell culture All cell cultures were tested for viral antigen by immunofluorescent Molecular method RT-PCR specific for a 419-bp region of the L gene of the filoviruses A confirmatory RT-PCR was performed on the filovirus-positive samples to amplify a 428-bp region of the EBOV NP 34

35 Other test Thrombocytopenia <150,000 cells/µl ALT, AST Coagulation profile 35

36 On isolation of patients use of strict barrier nursing procedures Present treatment strategies are mainly symptomatic and supportive Hydrating the patient, maintaining their oxygen status and blood pressure and treating them for any complicating infections Is there any role of Ribavarin in Ebola? No in-vitro or in-vivo effect on filoviruses severe adverse effects associated with the drug Ribavirin is not recommended for Ebola virus infections 36

37 What drugs exist to combat the disease? Combines two different serums made by two different companies San Diego firm Mapp Biopharmaceutical & ZMAb ( Canadian company Defyrus Inc) August 2013, Mapp Biopharmaceutical -working with the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID) Biological weapon 37

38 Inject Ebola into mice, and extract three types of antibodies that fight different parts of the virus spliced in human DNA to produce chimera antibodies acceptable to humans MB-003 The next challenge was producing enough MB-003 for an effective dose.antibodies could be grown inside genetically engineered Nicotiana Benthamiana (Australian tobacco plant) Testing the MB-003 serum on monkeys 43% of the infected monkeys survived In June 2012, Defyrus tested ZMAb in Rhesus Macaques -100% of infected monkeys survived (24hr) & 50% survived when treated 48 hours after exposure Before ZMapp could begin human trials and get approval from the U.S. FDA Ebola outbreak began in Guinea Two American missionary workers infected with Ebola (Kent Brantly and Nancy Writbol) ZMapp were given Improved 38

39 TKM-Ebola is an exprimental drug for Ebola disease Developed by Tekmira Pharmaceuticals Corp Small interfering RNAs targeting three of the seven proteins in Ebola virus: L polymerase membraneassociated protein (VP24), and (VP35) phase 1 trial 39

40 Standard precaution measures Vaccine Active case identification and isolation of patients Identifying contacts of ill or deceased persons and tracking the contacts daily for the entire incubation period of 21 days The aim - to avoid contact with the blood or secretions of an infected patient Investigation of retrospective and current cases to document all Direct contact with the body of the deceased patient should be historic and ongoing chains of virus transmission Identifying deaths in the community and using safe burial practices Daily reporting of cases avoided Education of health-care workers -appropriate use of personal protective equipment 40

41 Practice careful hygiene Avoid contact with blood and body fluids Do not handle items that may have come in contact with an infected person s blood or body fluids Avoid funeral or burial rituals that require handling the body of someone who has died from Ebola Avoid contact with animals and raw meat Avoid hospitals where Ebola patients are being treated After you return, monitor your health for 21 days and seek medical care immediately if you develop symptoms of Ebola 41

42 Hand Hygiene Perform hand hygiene immediately after removing PPE. If hands become visibly contaminated during PPE removal, wash hands before continuing to remove PPE Wash hands with soap and water or use an alcohol-based hand rub * Ensure that hand hygiene facilities are available at the point needed, e.g., sink or alcohol-based hand rub PPE Use in Healthcare Settings PPE Used in Healthcare Settings Gloves protect hands Gowns/aprons protect skin and/or clothing Masks and respirators protect mouth/nose Goggles protect eyes Face shields protect face, mouth, nose, and eyes 42

43 Key Points About PPE Before contact with the patient - generally before entering the room Use carefully don t spread contamination Remove and discard carefully, either at the doorway or immediately outside patient room Remove respirator outside room Immediately perform hand hygiene 43

44 Sequence for Donning PPE Gown first Mask or respirator Goggles or face shield Gloves Sequence for Removing PPE Gloves Face shield or goggles Gown Mask or respirator 44

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47 Public Health Agency of Canada (PHAC) has donated up to 1000 doses of its experimental VSV-EBOV candidate Consists of transgenic vesicular stomatitis virus that expresses the Ebola glycoprotein The vaccine, which has only been tested in animals, protected 100% of macaques when administered 21 days before an otherwise fatal infection when administered immediately after exposure to Ebola: when it was given to primates 30 minutes after inoculation with the virus - four out of eight survived NIH and GlaxoSmithKline A recombinant adenovirus that expresses the glycoproteins of two different strains of Ebola virus 100% protection when used prophylactically in primates phase 1 trials 47

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49 Objectives of Epidemic Preparedness and Response 1. Anticipation/prediction so that epidemics be prevented 2. Early detection to know when there is a problem 3. Rapid Response guidelines/trained staff/supplies in place before epidemic 4. Effective Response appropriate control methods adequate resources and logistics Outbreak Detection and Response Without Preparedness First Case Late Detection Delayed Response CASES DAY Opportunity for control 49

50 Outbreak Detection and Response With Preparedness Early Detection Rapid Response CASES DAY Potential Cases Prevented Components of Epidemic Preparedness 50

51 No need to panic "put in operation the most advanced surveillance and tracking systems" for the hemorrhagic virus The government is setting up centres at airports and ports to deal with travellers showing any potential symptoms of Ebola, spread through close contact with bodily fluids of people who who are sick. All air passengers arriving in India from Ebola-affected countries must now fill in a symptom-checklist form and provide addresses as the government builds a database to track people who might develop symptoms. 51

52 Syrian golden hamster Guinea pig African green monkeys Mice Baboons Cynomolgus monkey Be Prepared! 52