Dr. Saja Alkafajy - Air Borne Infections Lecture 1 PDF

Control of Communicable diseases AIR BORNE INFECTIONS Seasonal influenza By Dr. Saja Alkafajy  AIR BORNE INFECTIONS A mechanism of transmission of an infectious agent by particles, dust, or droplet nuclei suspended in the air. Droplet nuclei ar...

Control of Communicable diseases AIR BORNE INFECTIONS Seasonal influenza By Dr. Saja Alkafajy  AIR BORNE INFECTIONS A mechanism of transmission of an infectious agent by particles, dust, or droplet nuclei suspended in the air. Droplet nuclei are tiny particles (1 - 10 microns) that represent the dried residue of droplets.  General Prevention and Control Measures 1.Ventilation : Since organisms transmissible through the air can be widely dispersed, specific air ventilation is required to manage their dispersion thus control outbreaks of airborne infections. If resources are available then (especially in healthcare facilities) techniques such as the use of monitored negative airflow ventilation with at least six air changes per hour and filtration of direct exhaust to the outside should be used. In routine areas of work and stay adequacy of ventilation at all times is ensured by provision of at least two windows per room with an area of about 10 percent of the floor space and arranged so as to provide cross ventilation 2. Avoid Overcrowding : Other important measure, for preventing airborne infections is prevention of overcrowding. Beds must be spaced with an interval of at least two meters between the centres of the two adjacent beds.  General Prevention and Control Measures 3. Respiratory Protection Devices : Surgical masks that cover the mouth and nose should be worn by healthcare staff in hospitals and by the patient themselves also. N95 respirator- surgical mask are currently recommended.  INFLUENZA Influenza is an acute respiratory tract infection caused by influenza virus , characterized by sudden onset of chills, malaise, fever, muscular pains and cough. There are 4 types of influenza viruses, types A, B, C and D. Influenza A and B viruses circulate and cause seasonal epidemics of disease.  Influenza A viruses are further classified into subtypes according to the combinations of the proteins on the surface of the virus. Currently circulating in humans are subtype A(H1N1) and A(H3N2) influenza viruses. The A(H1N1) is also written as A(H1N1)pdm09 as it caused the pandemic in 2009 and replaced the previous A(H1N1) virus which had circulated prior to 2009. Only influenza type A viruses are known to have caused pandemics. Influenza B viruses are not classified into subtypes but can be broken down into lineages. Influenza type B viruses belong to either B/Yamagata or B/Victoria lineage. Influenza C virus is detected less frequently and usually causes mild infections, thus does not present public health importance. Influenza D viruses primarily affect cattle and are not known to infect or cause illness in people  Epidemiology All age groups can be affected but there are groups that are more at risk than others. People at greater risk of severe disease or complications when infected are pregnant women, children under 5 years of age, older people, individuals with chronic medical conditions (such as chronic cardiac, pulmonary, renal, metabolic, neurodevelopmental, liver or hematologic diseases) and individuals with immunosuppressive conditions/treatments (such as HIV, receiving chemotherapy or steroids, or malignancy). Health care workers are at high risk of acquiring influenza virus infection due to increased exposure to the patients, and of further spreading particularly to vulnerable individuals. Vaccination can protect health workers and the people around them. Epidemics can result in high levels of worker/school absenteeism and productivity losses. Clinics and hospitals can be overwhelmed during peak illness periods. Hospitalization and death due to influenza occur mainly among high-risk groups. In industrialized countries most deaths associated with influenza occur among people aged 65 years or older. The effects of seasonal influenza epidemics in developing countries are not fully known, but research estimates that 99% of deaths in children under 5 years of age with influenza related lower respiratory tract infections are in developing countries Mode of transmission: Influenza is spread mainly from person to person by droplet infection or droplet nuclei created by sneezing, coughing or talking. The portal of entry of the virus is the respiratory tract. Incubation period: 1-4 days (2days)  SIGNS AND SYMPTOMS Symptoms of influenza usually begin around 2 days after being infected by someone who has the virus. Symptoms include: sudden onset of fever cough (usually dry) headache muscle and joint pain severe malaise sore throat runny nose. The cough can be severe and can last 2 weeks or more.  Diagnosis Laboratory confirmation is performed using direct antigen detection, virus isolation, or detection of influenza-specific RNA by reverse transcriptase-polymerase chain reaction (RT-PCR).  Treatment Most people will recover from influenza on their own. People with severe symptoms or other medical conditions should seek medical care. People with mild symptoms should: stay home to avoid infecting other people rest drink plenty of fluids treat other symptoms such as fever seek medical care if symptoms get worse.  Treatment People at high risk or with severe symptoms should be treated with antiviral medications as soon as possible. They include people who are: pregnant children under 59 months of age aged 65 years and older living with other chronic illnesses receiving chemotherapy living with suppressed immune systems due to HIV or other conditions.  Prevention and Control measures Vaccination is the best way to prevent influenza. Safe and effective vaccines have been used for more than 60 years. Immunity from vaccination goes away over time so annual vaccination is recommended to protect against influenza. The vaccine may be less effective in older people, but it will make the illness less severe and reduces the chance of complications and death. Vaccines are updated routinely with new vaccines developed that contain viruses that match those circulating. Several inactivated influenza vaccines and recombinant influenza vaccines are available in injectable form. Live attenuated influenza vaccines are available as a nasal spray. Vaccination is especially important for people at high risk of influenza complications. Annual vaccination is recommended for: pregnant women children aged 6 months to 5 years people over age 65 people with chronic medical conditions health workers.  The influenza vaccine isn't 100% effective, so it's also important to take several measures to lower the spread of infection, including: 1. Wash your hands well and often with soap and water for at least 20 seconds. If soap and water aren't available, use an alcohol-based hand sanitizer with at least 60% alcohol. Make sure friends and family that you're around regularly, especially kids, know the importance of hand-washing. 2. Avoid touching your face. Keeping your hands away from your eyes, nose and mouth helps keep germs away from those places. 3. Cover your coughs and sneezes. Cough or sneeze into a tissue or your elbow. Then wash your hands.  4. Regularly clean often touched surfaces to prevent spread of infection from touching a surface with the virus on it and then your face. 5. Avoid crowds. The flu spreads easily wherever people gather in child care centers, schools, office buildings and auditoriums and on public transportation. By avoiding crowds during peak flu season, you lower your chances of infection. 6. Also avoid anyone who is sick. And if you're sick, stay home for at least 24 hours after your fever is gone so that you lessen your chance of infecting others.  Vaccination 1. Inactivated influenza vaccine (IIV) Administered by intramuscular injection 2. Live, attenuated influenza vaccine (LAIV) Administered intra nasally 3. Recombinant influenza vaccine (RIV) Administered by intramuscular injection Infectious diseases will last as long as humanity itself" THANK YOU