Viral Haemorrhagic Fevers-PDF

Viral Haemorrhagic Fevers  Viral Haemorrhagic Fevers (VHF) Group of severe illnesses; sharing certain clinical manifestations (haemorrhage ,fever, shock) caused by four groups of RNA viruses. Most of VHF infections occur in “outbreaks”. Due to their severity of infection and their abi...

Viral Haemorrhagic Fevers  Viral Haemorrhagic Fevers (VHF) Group of severe illnesses; sharing certain clinical manifestations (haemorrhage ,fever, shock) caused by four groups of RNA viruses. Most of VHF infections occur in “outbreaks”. Due to their severity of infection and their ability to spread widely among population they can be used as “Biological weapons” (Bioterrorism). 1- FILOVIRIDAE, 2 – ARENAVIRIDAE, 3 – BUNYAVIRIDAE, 4 - FLAVIVIRIDAE  1- FILOVIRIDAE Genus Filovirus: Ebola. Structure: Marburg. Filamentous, Pleomorphic Width 80nm –Length 970nm. Enveloped. Helical nuleocapsid. Linear Single stranded , non- segmented RNA – ve sense.  2 - ARENAVIRIDAE Genus Arenavirus. 110-130 nm. Old world arena viruses : Dense granular Lassa Fever (west africa: ( Ribosomes acquired from host Nigeria) cells) New world. Enveloped. capsid helical symmetry. ssRNA segmented (2 segments ). 3 - BUNYAVIRIDAE 80-120nm. Enveloped. capsid helical. ss RNA segmented 3 L,M,S.  4 - FLAVIVIRIDAE 30-60 nm. Genus: enveloped. Flavivirus: capsid icosahedral. Yellow fever virus. ssRNA linear +ve sense. Dengue virus.. Others  Multi organ affection: – Liver. – CNS. – Kidneys. – Other.  Ebola Select this paragraph to edit  Ebola First identified in 1976 in Zaire (DRC ). Reported in South Sudan in 1979. Most severe form of VHF. Mortality rates up to 90% with zaire-ebolavirus. Occurs as epidemic. No animal reservoir found (possibly Bats and other primates).  Ebola Select this paragraph to edit 5 subtypes: Ebolavirus Zaire. Ebolavirus Sudan. Ebolavirus Cot’ivoir. Ebolavirus Bundibugyo. Ebolavirus Reston. Transmission: Direct contacts with patients body secretions (blood , saliva, semen, tissues etc). High risk: Caregivers and Family members  Ebola Pathogenesis: Classical VHF plus extensive widespread necrosis in: Liver. Spleen. Kidneys. Heart. Lymph-nodes. DIC  Ebola: Clinical features Incubation period:2-21 days. Prodrome phase: Bleeding stage: Sudden onste. – Rash. Non specific symptoms. – Petechia. Photophobia & conjunctival congestion. – Ecchymosis. Chest pain, cough & – Blood oozing. pharyngitis. – Upper & lower GI Lymphadenopathy. bleedings. – Eye bleeding.  Ebola: Clinical features Late stage: Complications: CNS. – Shock. Delirium. – Abortion. Psychosis. – Hearing loss. Coma. – Carditis. – Mortality rate up to 90%.  Ebola: Diagnosis Complete Blood count (leukopenia, lymphopenia and thrombocytopenia). Liver function test. Virology: Serology: ELISA, IFAT. Molecular: RT-PCR. Other: Ag detection ,viral isolation. Immunohistochemistry ( post mortem). EBOLA: Management antiviral therapy under trails. Supportive therapy. Maintain fluid & electrolytes balance. EBOLA: Prevention vaccine under trails. “Notifiable disease”. Isolation of cases. Health staff precautions. Use barriers; goggles ,masks ,gowns, gloves. Proper environmental “decontamination”. Cadavers care (incineration or careful burial.  Dengue Fever Select this paragraph to edit  Dengue Fever the most common Arboviral infection in humans. Highest prevalence in Southeast Asia. Several outbreaks occurred at Eastern Sudan states. Dengue fever Dengue Virus has 4 subtypes: Risk factors DEN-1,DEN-2, DEN-3,DEN-4. – Age. Partially homotypic: – Gender. infection with one serotype – Preexisting confers lifelong homotypic antibodies. immunity to that serotype & a partial heterotypic immunity to – Serotype. other serotypes – Genetic factors. – Hyperendemicity. Transmission: – Aedes aegypti. – Early morning & late afternoon feeder.  Dengue fever: Pathogenesis Pathogenesis of VHF plus: Ab dependent enhancement: Marked vascular Primary infection  Ab-virus permeability…..shock. complex non infectious complex  Hepatic involvement. recovery. Secondary infection with other CNS involvement. serotype  cross reacting non- neutralizing Ab. Ab-virus complex infectious complexes  vascular injury Dengue fever: Clinical features Incubation period:3-14 days. 4 syndromes: Undifferentiated fever. Classical Dengue fever. Dengue haemorrhagic fever (DHF). Dengue shock syndrome (DSS).  Dengue fever: Clinical features Undifferentiated fever. Dengue fever: Usually in children Occur in older children. Mild febrile illness. Sudden onset of high Following primary infection. grade fever. Frontal headache. Retro-orbital pain. Arthralgia & myalgia. Rash. Dengue fever: Clinical features Dengue shock syndrome (DSS): Dengue haemorrhagic fever – 4 criteria of DHF. (DHF). : – Evidence of circulatory 4 criteria: failure & shock. Fever. Haemorrhagic manifestations. Low platelet count. Other: Evidence of plasma leakage. – CNS manifestations. – Hepatic failure. – Carditis.  Diagnosis: Haematological: Supportive treatment. Haematocrit. Platelet count. tWBC count. Virological: Vaccine under research. Viral isolation. Mosquito control. Serology ELISA and others. RT-PCR.  Yellow Fever Select this paragraph to edit Yellow Fever An arboviral infection range from acute febrile illness to life threatening viral haemorrhagic fever. The largest prevalence in Africa and South America. In Sudan; outbreaks occurred in South Kordufan in 2005,last one 2010. Transmission is by mosquitoes (Aedes and haemogogus).  Liver: extensive hepatocellular necrosis (midzonal distribution.). Kidney: fatty changes & tubular necrosis. Heart: myocardial death. CNS: vascular injury. Lymphoid tissues: Germinal necrosis.  Yellow Fever: clinical features Incubation period3-6 days. Mild disease. Mild disease. – Fever Severe (malignant) disease. – Headache – – Epistaxis. – jaundice.  Yellow Fever: Clinical features Malignant disease: Phase 3: Phase1: Toxic phase: Non specific symptoms. Haemorrhagic Phase 2: manifestation. Remission of phase1 symptoms. Deep jaundice. CNS manifestations. Renal manifestations.  Yellow Fever: Diagnosis Haematological: – Haematocrit. Virological: – Low tWBC. – Viral isolation. – Low Platelet count. – Serology ELISA and Liver function test: elevated others. enzymes. – Antigen detection ,IF Renal function test. – RT-PCR. low albumin. Urine: marked albuminurea. Cardiac: ECG ,cardiac enzymes Yellow Fever: Management: Supportive. Prevention: – Personal protective measures. – Mosquito control. – Vaccination. Yellow fever vaccine:  Rift Valley Fever Select this paragraph to edit Rift Valley Fever Viral zoonotic infection causes severe disease in domestic animals (Livestock) and human. Several outbreaks occurred in Africa (Sudan , Kenya) and Arabic peninsula (Saudi Arabia and Yemen  Zoonotic infection. Epizootic (live stock problem). Epidemic occur in rainfalls Pathogenesis: floods. liver…..hepatocellular necrosis. Transmission: Endothelia damage. Contact with blood, other body fluids Eye….Retinitis. or organs of infected animals or man. CNS….Encephalitis.. Bite of infected mosquito. Ingestion of infected meal or raw milk. Inhalation through aerosol.  ncubation period:2-6days. Outcome of the infection Symptomatic Asymtomatic Complications Most resolve Meningoencephalitis Occular disease Haemorrhagic fever Hepatitis  RVF: Diagnosis: Haematological: Virological: Haematocrit. – Viral isolation. tWBC. – Serology ELISA and Platelet count. others. Liver function test. CSF analysis. – Antigen detection ,IF – RT-PCR.  Mosquito control. Supportive. Animal control by: Ribavirin??. – Vaccination: Interferon α??. Live attenuated + killed.