Emerging & Re-emerging Infectious Diseases PDF

EMERGING & RE-EMERGING INFECTIOUS DISEASE PROF. RAGHDA EL-SAYED FARAG Objectives Definitions Examples Factors affecting emerging infections Avian flu Swine flu Sars Zika fever  Emerging infections: Infectious diseases that have newly appeared in a population or have...

EMERGING & RE-EMERGING INFECTIOUS DISEASE PROF. RAGHDA EL-SAYED FARAG Objectives Definitions Examples Factors affecting emerging infections Avian flu Swine flu Sars Zika fever  Emerging infections: Infectious diseases that have newly appeared in a population or have existed but are rapidly increasing in incidence or geographic range (Avian flue, Swine flue, Zika virus, SARS, COVID-19). Re-emerging infections: The reappearance of a previously known infection after a period of disappearance or decline in incidence (TB, Cholera, Malaria, Dengue). Factors affecting emerging infections Host factors: Human behavior Human susceptibility to infection (immunosuppression) International travel & commerce Pathogen factors: High frequency of mutations Co-evolution and pathogenicity Development of resistance to drugs Environmental factors: Changing climate and eco-systems Technology and Industry AVIAN (BIRD) FLU MICROBIOLOGY Avian influenza typically refers to influenza A virus. Most well-known HPAI (highly pathogenic avian influenza) strain is H5N1. EPIDEMIOLOGY Human infections first reported in 1997 in Hong Kong. Since 2003, more than 700 human cases have been reported to the WHO. Viruses are easily transmissible and fetal among birds and of seasonal flue infection to human. TRANSMISSION 1. Direct or indirect contact with infected live or dead poultry. 2. Contact with avian influenza A virus-contaminated environments. 3. Human-to-human transmission occurs ONLY with mutations. SYMPTOMS Incubation period (3-7 days) Malaise High grade fever >38°C Headache Cough / sore throat Tiredness Runny / blocked nose Limb or joint pain Sneezing Diarrhea / vomiting / abdominal pain / chest pain / bleeding from nose and gum COMPLICATIONS Hypoxemia (dyspnea) Pneumonia Acute respiratory distress Respiratory failure Multiple organ dysfunction Secondary bacterial and fungal infections SWINE FLU Swine flu is caused by H1N1 influenza virus that infects the respiratory tract of pigs. H1N1 is one of several influenza virus strains that can cause seasonal flu in human. H1N1 appears to be mostly due to a combination of human influenza, swine and avian viruses 2009 swine flu pandemic is the third recent flu pandemic involving the H1N1 virus: a. The first was the 1918–1920 Spanish flu pandemic b. The second was the 1977 Russian flu 1918 Pandemic Flu (Spanish Flu) 1918 Influenza Flu Outbreak Estimated 60 to 80 Million Deaths Worldwide First Wave – Beginning March 1918 Mild Seasonal Flu Virus Second Deadly Wave – Summer/Fall of 1918 Virus Mutated to a More Deadly Strain Majority of the Fatalities – In the Second Wave Primarily in the (20 – 40)-Year-Old Age Range MODE OF TRANSMISSION 1. Direct droplet transmission from cough or sneeze of an infected person. 2. Indirectly through surfaces contaminated from an infected case. 3. Improper handling and cooking of pork products from swine infected with H1N1 virus. SYMPTOMS COMPLICATIONS Same as seasonal flu Same as seasonal Flue Mention? Mention? DIAGNOSIS Sample 1. Nasopharyngeal aspirate / wash 2. Oropharyngeal / throat swab Tests Viral culture Reverse transcription polymerase chain reaction (RT-PCR) Rapid influenza diagnostic tests (RIDTs) TREATMENT 1. Hospitalization and isolation 2. General and supportive treatment: Monitor vital signs Maintain hydration, electrolytes, and nutrition Paracetamol for fever 3. Oseltamivir (Tamiflu) 75 mg twice daily for 5 days SEVERE ACUTE RESPIRATORY SYNDROME (SARS) DEFINITION: Severe acute respiratory syndrome (SARS) is a viral respiratory illness of zoonotic origin caused by SARS-associated coronavirus (SARS-CoV-1). Caused the 2002-2004 SARS outbreak No cases of SARS-CoV-1 have been reported worldwide since 2004 TRANSMISSION 1. Direct droplet transmission from cough or sneeze of an infected person. 2. Indirectly through surfaces contaminated from an infected case. SYMPTOMS COMPLICATION Fever, chills Dry cough Fatigue Pneumonia Headache Dyspnea Sore throat Hypoxia (fatal) Muscle pain 2ry bacterial infections Diarrhea (10-20% of patients) Multi-organ failure (GI, liver, kidney) DIAGNOSIS CT chest Indicative for atyptical pneumonia or acute respiratory distress syndrome ELISA, immunuflourescence For SARS-CoV-specific antibodies PCR For virus identification TREATMENT 1. Hospital admission (isolation, close observation) 2. Treatment is supportive: Ventilator to deliver oxygen (assist breathing) Antibiotics (for pneumonia and secondary bacterial infections) High dose steroids (reduce swelling in lungs) MIDDLE EAST RESPIRATORY SYNDROME (MERS) DEFINITION: Viral respiratory infection caused by Middle East respiratory syndrome coronavirus (MERS-CoV) belonging to the genus betacoronavirus which is distinct from SARS coronavirus and common-cold coronavirus EPIDEMIOLOGY The first case was identified in June 2012 in Jeddah, Saudi Arabia Larger outbreaks have occurred in: − South Korea in 2015 − Saudi Arabia in 2018 TRANSMISSION Humans are typically infected from camels, either during direct contact or indirectly. Human-to-human spread typically requires close contact with an infected person (healthcare or household setting), so risk to global population is considered low SYMPTOMS Range from asymptomatic disease to severe pneumonia leading to ARDS. Complications include: 1. Kidney failure 2. DIC 3. Pericarditis DIAGNOSIS 1. RT-PCR testing of blood and respiratory samples 2. ↓ white blood cell count, especially ↓ lymphocytes TREATMENT and PREVENTION same as SARS. ZIKA FEVER Zika virus Zika virus is a member of virus family flaviviridae TRAMSMISSION 1. Spread by daytime-active Aedes aegypti mosquitoes 2. Sexual contact 3. Blood transfusion 4. Vertical (mother-to-child) transmission EPIDEMIOLOGY Since the 1950s, it occured sporadically from Africa to Asia. From 2007 to 2016, the virus spread eastward, across the Pacific Ocean to the Americas, leading to the 2015-2016 Zika virus epidemic. SIGNS AND SYMPTOMS COMPLICATIONS Incubation period 3-14 days 1. Infection during pregnancy: Typically asymptomatic a. Pregnancy complications (fetal loss, stillbirth, and preterm birth) Mild symptoms usually last 2-7 days: b. Microcephaly + congenital 1. Low fever abnormalities in the developing fetus 2. Maculopapular rash and newborn 3. Conjunctivitis 2. Guillain-Barré syndrome 4. Muscle and joint pain 3. Neuropathy 5. Malaise / headache 4. Myelitis  Zika Rash & conjunctivitis Aedes Aegypti Anencephaly Diagnosis Molecular testing for presence of the virus: RT-PCR for ZIKV RNA Immunoassay for viral proteins Virus isolation for live virus Serological testing for presence of antibodies(ELISA) Not recommended since antibodies against Zika: − Persist for years − Cross-react with other similar viruses, including dengue A positive lab result often cannot definitively tell you if you have a current or past infection or whether it is a Zika or dengue infection Treatment No specific treatment for Zika virus infection Fluids to prevent dehydration. Paracetamol for joint pain and fever. Thank You