What is the Dengue Virus? Arbovirus Arbovirus Arthropod, Mosquito, born (Aedes aegypti) It is a pathogen that causes Dengue fever (DF) Dengue hemorrhagic fever (DHF) Can lead to Dengue shock syndrome (DSS) Has four different serotypes (DEN-1,2,3,4) First reported epidemics in 1780 in Asia, Africa, and North America
Target tissues Dengue induces cytokine production in cells Cytotoxic factor effects endothelial cells involved in most of the following: Heart Liver Kidneys Lungs Intestines Spleen Lymph nodes Brain Skin (inflammatory rashes)
Symptoms: DHF Fever Headache Muscle and joint pain Dehydration Nausea and/or Haematemesis (vomiting of blood) Epistaxis (Bleeding from the nose, mouth, or gums) Haematuria (Blood in Urine) Pain behind the eyes Plasma leakage Respiratory distress Petechia (Skin rash) and/or Purpura (Lesions)
Diagnostic tests Virus isolation by infection of mice using infected mosquitoes Detection of IgM antibodies in the blood by PCR or Viral isolation (Serology) ELISA (Enzyme-Linked Immunoabsorbent assay) ELISA Thrombopenia Raised hematocrit
Pathogenesis and infection process of Dengue Humans are initially infected through a mosquito vector Initial interaction with cell occurs with the viruses ability to infect cell Primary target, Phagocytes Virus uses cell receptor molecule to enter cell Cell receptor molecules include: Glycosaminoglycan Heparan Sulfate (Expressed in almost all cell types) Virus replicates in target organs Infects white blood cells and lymphatic tissues Virus is released and circulates in blood Alternate mosquito then bites host and receives virus
Prevention: There is no specific treatment Relieving symptoms and complications: Plasma volume replacement Sedatives for restless patients Blood transfusion with patients with significant blood loss Aspirin should be avoided All efforts of control are aimed against mosquitoes Elimination of breeding areas Actions to prevent mosquito bites (repellant, nets, and vapors) Vaccinations are pending Problem is that the vaccination needs to prevent all four serotypes vaccination Treatment: DHF
Epidemiology Affects humans Is prominent in tropical environments Ideal for Mosquito habitats What is promoting the disease? Global warming is causing climate changes which is causing the disease to move to more environments (higher altitudes and amplitudes) More habitats for mosquitoes to thrive in Spread has been increased by urbanization and population growth Inability of mosquito control in countries is also a major factor
Morbidity and Mortality More than 2.5 Billion people live in areas that have a risk of infection Over 100 million cases of Dengue infection are reported each year globally 500,000 cases pertain to DHF DHF has a 5% fatality rate for those infected People at high risk are children and the elderly
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