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Viral Droplet Infections Dr. Abd El hamied Mohamed Abd El hamied Lecturer of Occupational Health & Industrial Medicine Viral Droplet Infections Seasonal Influenza Avian Influenza Swine Influenza Seasonal influenza Avian Influenza Swine flu Acute highly Infectious viral Acute infection infectious viral disease of birds. caused by Type disease Some (AI) A influenza characterized by viruses can cause viruses (H1N1 fever, general & infections subtype). catarrhal (clinical or manifestations. subclinical) in humans. Public health significance: Seasonal influenza Occurs as sporadic cases, outbreaks, epidemics & pandemics. In the last century, there are 3 pandemics. During epidemics, clinical attack rates range from 10-20% in general population to >50% in closed population. Influenza epidemics evolve rapidly, spread widely with serious complications & death especially in elderly & patients with chronic debilitated diseases. Avian Influenza 1st direct bird to human spread of H5NI occurred in Hong Kong in 1997. Re-emergence in December 2003 & spread from Asia to Europe & Africa (pandemic), resulting in millions of poultry infections, hundreds of human cases & many human deaths. In Egypt, 1st direct bird to human spread of H5N1 occurred in 2006 & total cases in 2009 were 85 with a total deaths of 27 (CFR is 31.7%) Globally ► general CFR reached 50%. Swine flu In April 2009 ►WHO declared a "public health emergency of international concern" when 1st 2 cases of H1N1 virus were reported in US, followed by hundreds of cases in Mexico. In April 2010,CFR was at least 17.700 deaths worldwide. Risk factors : extremities of age pregnant females individuals with syst emic diseases. In Egypt in 2009 → 808 cases were confirmed with 2 deaths (CFR around 0.2%). In Aug-2010, WHO declared that swine flu pandemic officially over. Causative agent Seasonal influenza Type A: epidemics & pandemics. Type B: regional epidemics Type C: sporadic cases & localized outbreaks. ☻Has 2 antigens projecting from its surface: Haemagglutinin (HA) Neuraminidase (NA) 16 known subtypes 9 known subtypes Site of attachment to host Helps releasing newly cells formed viruses from host cells WHO nomenclature for influenza Strain type (A, B or C) / Geographical origin / Laboratory reference number/ year of occurrence / (description of H&N antigens). For example; A/ Mississippi/1/85/ (H3N2) Antigenic drift Antigenic shift of Modification of HA & NA Replacement proteins, viral proteins → a new viral mostly due to variant of A subtype with genetic antibodies against recombination of previous strains are not human & animal able to neutralize this new influenza viruses → variant → regional a completely new A subtype → outbreaks & annual pandemic. epidemics Since 1918, the only 3 influenza A sub-types known to cause human disease are: H1N1, H2N2 & H3N2. Other subtypes such as H5N1 are rare. Since isolation of influenza virus in 1933, antigenic shifts occurred 3 times: in 1957, 1968 & 1977 (causing pandemic every time). • No cross immunity between different antigenic strains. Avian Influenza Current pandemic is caused by subtype H5N1. Swine flu Type A influenza viruses (H1N1 subtype). Resistance: Killed at 70C,by Killed by heat& oxidizing alcohol, vinegar & agents. disinfectants. Reservoir of infection: Human cases (typical or Birds (wild & atypical)+ swine + avian Exit: Nasopharyngeal secretions domestic) + pigs Nasopharyngeal discharges, lacrimal discharges, faeces & blood. Human cases + pigs Period of infectivity: 3-5 days from clinical days onset in adult. 7 days children. in 1 day before up to 7 young sick. after becoming Modes of transmission Seasonal influenza 1. Direct droplet. 2. Nasal inoculation after hand contamination with virus. 3.Freshly contaminated articles with nasopharyngeal discharges. 4. Air borne: (droplet nuclei & infected dust). Avian Influenza 1. ANIMAL TO ANIMAL INFECTION: direct contact of susceptible animal to secretions (saliva, nasopharyngeal, feces or blood) of infected animals. Many different animals are infected including ducks, chicken, pigs, whales, horses & seals. 2. Animal to human infection: direct contact of humans with infected poultry, its discharges & feces. Antigenic shift & the danger of person to person transmission: If a pig is infected with both human influenza A virus & AI virus in the same time, mixing genes (Re-assortment) occur →a new virus → able to infect humans & spread from person to person resulting in an influenza pandemic. IP: 1-3 days Susceptibility: 1. Age: all ages are susceptible. 2.Immunity: Type specific & Transient immunity. Recurrent attacks due to multiple strains, genetic mutation & no cross immunity between different strains. 3.Environment: Cold, over-crowdness & ill ventilation. International 7 days. High Clinical Picture: moderate or severe form. Acute fever, headache, myalgia, prostration, back sore throat, rhinorrhea & cough. Self limited disease (recovery within 2-4 days). Complications: 1. 2ry bacterial infection e.g. bronchitis, 2. Children with salicylate therapy ►Reye disease (CNS & liver). + influenza-like Sub-clinical, mild, pain, fever symptoms. Diarrhea, vomiting, abdominal pain & bleeding from nose and gums. As seasonal human flu. Some people reported vomiting. have diarrhea + Diagnosis of Seasonal Influenza Laboratory Diagnosis 1.Direct identification of viral antigen nasopharyngeal cells by FA test or ELISA. 2. A rising titre of specific serum antibodies. in Diagnosis of Swine Flu Case classification: •Possible case: clinical +epidemiological criteria. •Probable case: clinical + epidemiological criteria + positive influenza rapid testing. •Confirmed case: laboratory confirmation Clinical criteria: one of the following: 1. Fever >38°C OR history of fever AND flu-like illness (≥2 of the following symptoms: cough, headache, rhinorrhea or vomiting/diarrhea). 2. Severe/life-threatening illness . •Epidemiological criteria: •At least one of the following in a person during the 7 days before onset of illness: 1. Close contact with a confirmed or probable case of swine flu A (H1 N1) virus infection. 2. Traveled to a geographical area known to have confirmed cases of swine influenza A/H1 N1 Prevention & Control Prevention: General: Specific: A. Active immunization: 1. Inactivated trivalent vaccine: Prevention + Control: Prevention: A. General A. General 1. General 1. HE of public: measures of Wash your hands. prevention for droplet & Avoid touching your contact eyes, nose or mouth infections. Nature : Killed containing 2 subtypes of A virus (H1N1 2. Measures for & H3N2), B strain (currently patients with AI: circulating strains present in a. the locality). Isolation: ☻Efficacy: 80% fever reduce complications by with 60% & death by 80 %. in hospital Avoid touching surfaces contaminated with virus. standard Healthy habits during precautions. cough & sneezing. b. Nursing 2. Measures for swine: precautions: hand ☻ Dose: 2 doses 0.5 ml I.M. for hygiene, gloves, gowns, eye protection, children not immunized disposable blood pressure cuffs, before. thermometers, etc. Single dose if immunized c. Tamiflu: anti viral before. drug of choice. ☻ Indications: 3. 1. Old aged persons > 65 years 2. Chronic Measures HCWs: for Standard precautions, numbers of infected & potentially infected animals. Quarantine: infected vaccination to ↓ risk of 3. HCWs. co-infection 4. Immunosuppressed. human & avian strain. with putting farms in quarantine. Cook debilitating surveillance, diseases. Culling: killing large pork thoroughly. Avoid markets. live animal 2. LA intranasal vaccine: 2 subtypes A&B Heat sensitive vaccine. 4. Measures during food preparation especially poultry: B. Specific prevention Vaccination of at risk groups e.g. Indication: only for healthy b. Hand washing people aged 5–49 ys. with soap & water pilgrims. 0.5 ml intranasal. a. Produces local & systemic Handling poultry. immunity. Hygienic of raw after handling or raw 1. Admantadine HCL: frozen adults 200 mg chicken or eggs. (children100 mg) orally c. Cook all poultry for 10 days. & products to a 2. Remantadine HCL: for high temperature > 70. influenza A but not B. B. Chemoprophylaxis: Side effects: fever & CNS (5-10 % of cases). d. Eggs should not be consumed raw or partially cooked. Contraindicated in patient with psychological or neurological disorders. 5. LAV given to poultry. Control of Seasonal Flu I. Case: Treatment: Antibiotics + Antiviral (Amantadine or Remantadine within 48 h of onset for 3-5 days). II. Contacts: Surveillance for IP. Chemoprophylaxis. III. Epidemic measures: 1. HE of the public, particularly high risk groups. 2. Immunization for high risk groups. 3. Surveillance of the community. 4. Adequate supplies of antiviral drugs & vaccination. Control of Swine Flu I. Case: Notification to WHO. Treatment: Tamiflu II. Contacts: Surveillance for maximum IP. Chemoprophylaxis. III. Epidemic measures: 1. Locally organized immunization programs for high risk groups. 2. Surveillance. 3. HE through media: about mode of transmission + prevention. MOH plan for flu pandemic, 2007 1. Database of all available health care settings. 2. ↑ number & quality of Labs for diagnosis of H1 N1virus. 3. HE of individuals, HCWs about signs , symptoms & prevention. 4. Vaccination of HCWs with seasonal flu vaccine. 5. Provision of a strategic store of Antiviral drugs. 6. Provision of a strategic store of PPE e.g. masks. 7. Quarantine measures & sentinel surveillance e.g. at airports & fever hospitals. ال إله إال أنت سبحانك إني كنت من الظالمين