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Viral Haemorrhagic Fevers

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Presentation on theme: "Viral Haemorrhagic Fevers"— Presentation transcript:

1 Viral Haemorrhagic Fevers

2 No vaccine for killer virus

3 S Africa fear over killer disease
More than 100 people in South Africa are under medical observation after coming into contact with people who died from suspected haemorrhagic fever. Images

4 Viral Haemorrhagic Fevers
Group of febrile illnesses RNA viruses from 4 families Highly infectious viruses Potential lethal syndrome Fever, malaise, vomiting, mucosal and GIT bleeding, hypotension, edema Most notorious Ebola case fatality rate 90%, 1995 Kikwik, Zaire Contracted from infected animal or arthropod vector International travel, nosocomial outbreaks

5 Images

6 Shared features Lipid envelope
Survival and perpetuation depend on animal host: natural reservoir Distributed all over the world, higher occurrence tropical areas e.g. South America, Africa, Pacific Islands Images

7 Shared features Transmitted 2 categories natural reservoirs: rodents or arthropods Transmission occurs through contact with: Natural reservoirs (mosquito bites, rodent bites) Excretions, secretions, blood reservoirs, intermediate hosts Person-to-person nosocomial infections Images

8 Pathophysiology Vascular bed attacked, microvascular damage and increased vascular permeability Specific pathophysiologic findings can vary depending on virus family and species Initial febrile illness, haemorrhaging skin and mucous membranes, orifices, effusions Widespread necrosis, may present any organ, modest and focal to massive in extent Liver, lymphoid system extensively involved Lung varying degrees interstitial pneumonitis, diffuse alveolar damage and haemorrhage ATN, microvascular thrombosis Minimal inflammatory response thromocytopaenia, leucocytosis

9 Morbidity and Mortality
Ebola, Marburg 25-100% mortality, pregnancy universally fatal High infection rate, especially Zaire type South-American HF case-infection ratio > 50% exposed Mortality rate 15-30% Lassa fever Fatality rate 2-15% Rift Valley Fever 1% exposed infected, mortality rate 50% Congo Fever Infection rate %, Fatality rate 15-30%

10 History Not all patients present with bleeding
Travel history, contact vectors, patient, bioterrorist attack Incubation period 2-14 d Initial symptoms non-specific Progressive fever, biphasic Chills Malaise Generalized myalgias, arthralgias Headache, anorexia,cough Severe sore throat Nausea, vomiting, diarrhoea, epigastric pain

11 Physical examination Findings not distinctive
Nonspecific conjunctival injection Facial/truncal flushing Petechiae, purpura,ecchymoses Icterus Epistaxis;GIT,GUT bleeding Lymphadenopathy Images Hypotension, shock, bradycardia, pneumonitis, pleural and pericardial effusions, haemorrhage Encephalopathy, seizures, coma, death

12 Arenaviridae Conjunctivitis, pharyngeal enanthema and petechiae, no exudate Sore throat Retrosternal pain Lassa fever: classic signs meningitis Swollen baby syndrome Infants toddlers; Lassa fever anasarca, abdominasl distension, bleeding Images

13 Bunyaviridae Retinal vasculitis, blindness Cotton wool spots macula
Severe disease bleeding, icterus, anuria, shock Encephalitis Congo fever most severe bleeding and ecchymosis Images

14 Filoviridae Ebola similar clinically more severe disease Marburg
5th day distinct morbiliform rash trunk, expressionless ghost-like facies Haemorrhage mucous membranes, venipuncture sites, body orifices DIC late disease Images

15 Flaviviridae Yellow fever
Midzone necrosis liver, jaundice d3, flushing face, congested conjunctivae, reddening edges tongue Heart, kidney damaged Early haemorrhage, swelling bleeding gums prominent Images

16 Differential diagnosis
Rickettsial infections Bacterial infections Salmonella, shigella, gram negative infections Septicaemia Meningococcal, staph, strep, typhoid Leptospirosis Malaria Viral: Chikungunya, Sinbis, Herpes, influenza EBV Acute anemia Acute Leukemia, promyelocytic leukemia DIC Encephalitis HUS TTP Meningitis Sepsis Collagen vascular diseases

17 Lab studies FBC Liver enzymes Alb Proteinuria universal
Leucopenia, leucocytosis, thrombocytopenia, hemoconcentration, DIC Liver enzymes Alb Proteinuria universal Serological tests – Ab not detected acute phase; Direct examination blood/tissues for viral Ag enzyme immunoassay, virions EM specific and sensitive PCR MassTag PCR Images

18 Treatment Supportive, ICU Blood, platelets, plasma
Ribavirin – arenaviruses Congo, Lassa Vaccination: Yellow fever Electrolyte and fluid balance Images

19 VHF isolation precautions WHO and CDC guidelines
Wash hands as needed Isolate the patient Wear protective clothing Dispose of needles and syringes safely Dispose of waste safely Use safe burial practices

20 Decontamination and isolation
Contain disease Appropriate barrier mechanisms and negative pressure isolation Report infection control of hospital as well as local and state public health officials, notify laboratory directors CDC – expedite virus specific diagnosis (beyond scope local lab) and mobilization resources containment

21 Specific infection control recommendations
Strict adherence to hand washing Double gloving, impermeable gowns N-95 masks or air-purifying respirators Negative pressure isolation 6-12 air changes per hour Leg and shoe coverings Face shields or goggles Images

22 Specific infection control recommendations
Restricted access Dedicated equipment Point-of-care analysers Environmental disinfection 1:100 bleach solution Multiple infected patients same part hospital Portable high-efficiency particulate air filtered forced-air equipment Survivors remain contagious extended periods of time Fatalities promptly buried/cremated Contacts medical surveillance 21 d

23 Lab samples Specially handled and packaged for shipment to authorized labs Biosafety level 3 and 4 facilities

24 References Clare DJ, Ricketti AJ et al. Viral Hemorrhagic Fevers: Currentb Status of Endemic Disease and Strategies for Control. Infect Dis Clin N Am 20 (2006) 359–393. Marty AM,Jahrling PB, Geisbert TW. Hemorrhagic Fevers. Clin Lab Med 26 (2006) 345–386 Pigott DC.Hemorrhagic Fever Viruses. Crit Care Clin 21 (2005) 765– 783 All Images:

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