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Analysis of Laboratory-Based Surveillance Systems for Ebola and Viral Hemorrhagic Fevers in Thailand

This document presents a comprehensive situation analysis of laboratory-based surveillance systems for Ebola and other viral hemorrhagic fevers (VHFs) in Thailand. Discussed are the various viruses causing hemorrhagic fever, including Marburg and Lassa viruses, and their epidemiological characteristics, transmission methods, and clinical manifestations. The analysis highlights the need for improved surveillance and response strategies to effectively manage outbreak risks. Relevant details from the summit organized by the Public Health Science Research Institute are included, focusing on the critical role of laboratory diagnostics.

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Analysis of Laboratory-Based Surveillance Systems for Ebola and Viral Hemorrhagic Fevers in Thailand

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  1. Marburg and Lassa viruses ศาสตราจารย์ ดร.พิไลพันธ์ พุธวัฒนะ ศูนย์ความร่วมมือการวิจัยไข้หวัดใหญ่ภาควิชาจุลชีววิทยา คณะแพทยศาสตร์ศิริราชพยาบาลมหาวิทยาลัยมหิดล Situation analysis of laboratory-based surveillance system for Ebola and other VHF in Thailand จัดโดย สถาบันวิจัยวิทยาศาสตร์สาธารณสุข โรงแรมรามาการ์เดน ดอนเมือง 29 กันยายน 2557

  2. Viruses causing hemorrhagic fever • Filoviridae : Ebola and Marburg • Arenaviridae :Lassa fever, Junin and Machupo • Bunyaviridae :Crimean-Congo haemorrhagic fever, Rift Valley fever, Hantaanhaemorrhagic fever • Flaviviridae : yellow fever, dengue, Omsk haemorrhagic fever, Kyasanur forest disease

  3. Common characteristics of viruses causing HF • Enveloped virus with RNA genome • Wide range of natural hosts : zoonotic diseases and some are vector-borne viruses • Geographically restrict

  4. Symptoms of VHF • Specific signs and symptoms vary by type of VHF, but the initial signs and symptoms is nonspecific and difficult to provide differential diagnosis. • Initial symptoms: high fever, fatigue, loss of strength, muscle aches

  5. VHF in Africa • Yellow fever virus • Lassa fever virus • Marburg virus • Ebola virus • Crimean-Congo hemorrhagic fever virus

  6. Family Filoviridae is classified into 2 genera: Genus Marburgvirus Genus Ebolavirus

  7. Marburg virus • First discover in 1967 in Marburg and Frankfurt, Germany and in Belgrade, Serbia (Yugoslavia) • Source of infection: African Green monkeys from Uganda

  8. Marburg hemorrhagic fever outbreak • Germany and Yugoslavia 1967 • South Africa (origin from Zimbubwe ?) 1975 • Kenya 1980, 1987 • DR Congo 1998-2000 • Angola 2004-2005 • Uganda 2007, 2012 • 1990 Lab contamination in Russia • 2008 USA and Netherlands ex Uganda

  9. Transmission • Fruit bats, Rousettusaegyptiof the family Pteropidaeare reservoir hosts. • Transmission from bats to human may occur through contact with bat feces or aerosols. • Transmission from primates • Human to human transmission: contact to blood, secretions, body fluids/tissues, semen or contaminated equipment (household contact, nosocomial infection, burial ceremony)

  10. Pteropid bats

  11. Marburg hemorrhagic fever • Incubation period 5-10 days • High fever, severe headache, severe malaise, severe watery diarrhoea, abdominal pain and cramping. Nausea and vomiting can begin on the third day. • Fresh blood in vomitus and feces, bleeding from nose, gum and vagina. Spontaneous bleeding at venepuncture site • CNS involvement • Death occurs most often on between day 8 and 9, and usually preceds by severe blood loss and shock. • Case fatality rate 23-90%

  12. General properties of filovirus • RNA genome of negative polarity, linear • Envelope • Filamentous shape • Carry enzyme RNA dependent RNA polymerase in virion

  13. Lab diagnosis • RT-PCR • Ag detection • Ab detection by ELISA/NT assay • Virus isolation in cell culture

  14. Arenaviruses • Enveloped virus with single stranded RNA genome comprising 2 RNA segments: S and L. The genome is ambisense. • Presence of transcriptase in virion • S RNA segment (3400 bases) encodes for nucleocapsid protein (N) and glycoprotein. • L RNA segment (7000 bases) encodes for RNA polymerase.

  15. Lassa fever virus • First report in the town named Lassa in Nigeria in 1969 in 2 American missionaries who died from the disease. • It is endemic in West Africa in Sierra Leone, Liberia, Guinea and Nigeria. • Cases reported from Ivory coast, Mali, Ghana….. • Estimated number 100,000 to 300,000 cases with approximately 5,000 deaths per year

  16. Reservoir host of Lassa virus is a rodent known as the "multimammate rat" (Mastomysnatalensis). 

  17. Transmission • Mastomys rodents live in savannas and forest and around home. Rodents shed the virus in urine and droppings. • Man gets infection through ingestion and inhalation. • Human to human transmission through contact with blood, secretions, excretion and tissues and also nosocomial infection • Incubation period 1-3 weeks

  18. Signs and symptoms • Approximately 80% of Lassa fever virus infection are mild and undiagnosed. • Mild symptoms include mild fever, general malaise and weakness. 20% of the cases progress to severe disease and hemorrhage, repeated vomiting, facial swelling, pain in chest, back and abdomen and shock. Deafness is the most common complication. • Death occurs from multi-organ failure. • Fatality rate 1% or 15-20% of hospitalized cases

  19. Treatment • Ribavirin given at early illness.

  20. Lab diagnosis • Same as mentioned for Marburg

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