INFLUENZA AND RUBELLA INFECTIOUS DISEASE .pptx

all about influenza and rubella, epidemiology source of infection

1. INFLUENZA AND RUBELLA THIRISHA.D ROLL NO:89 II YEAR

2. OBJECTIVES: INTRODUCTON AGENT FACTORS HOST FACTORS MODE OF TRANSMISSION INCUBATION PERIOD PATHOGENESIS CLINICAL FEATURES INFLUENZA:

3. INTRODUCTION: Influenza is an acute respiratory tract infection caused by influenza virus Types Influenza A Influenza B Influenza C Influenza D The disease is characterized by sudden onset of chills, malaise, fever ,muscular pain and cough

4. AGENT FACTORS: Influenza virus are classified within the Orthomyxoviridae family. Of importance are the influenza A and B viruses which are responsible for epidemics of disease throughout the world. Influenza A virus has 2 distinct surface antigens - the haemagglutinin (H) and the neuraminidase (N) antigens. The H antigen initiates infection following attachment of the virus to susceptible cells. The N antigen is responsible for the release of the virus from the infected cell. The currently identified subtypes are 18 HA and 11 NA. The influenza A virus is unique among the viruses because it is frequently subject to antigenic variation, both major and minor. AGENT:

5. When there is a sudden complete or major change. it is called a shift, and when the antigenic change is gradual over a period of time, it is called a drift. Antigenic shift appears to result from genetic recombination of human with animal or avian virus, providing a major antigenic change. Antigenic drift involves "point mutation" in the gene owing to selection pressure by immunity in the host population. RESERVOIR OF INFECTION: It has become increasingly evident that a major reservoir of influenza virus exists in animals and birds. Many influenza viruses have been isolated from a wide variety of animals and birds (e.g., swine, horses, dogs, cats, domestic poultry, wild birds, etc. Some of these include the major H and N antigens related to human strains

6. SOURCE OF INFECTION: Usually a case or subclinical case. During epidemics, a large number of mild and asymptomatic infections occur, which play an important role in the spread of infection. The secretions of the respiratory tract are infective. PERIOD OF INFECTIVITY: Virus is present in the nasopharynx from 1 to 2 days before and 1 to 2 days after onset of symptoms.

7. HOST FACTOR AGE AND SEX: Influenza affects all ages and both sexes. In general, the attack rate is lower among adults. Children constitute an important link in the transmission chain. The highest mortality rate during an epidemic occurs among certain high-risk groups in the population such as old people (generally over 65 years of age), children under 18 months, and persons with diabetes or chronic heart disease, kidney and respiratory ailments. HUMAN MOBILITY: This is an important factor in the spread of infection.

8. IMMUNITY: Immunity to influenza is subtype specific. Antibodies against HA and NA are important in immunity to influenza. Resistance to initiation of infection is related to antibody against HA, which neutralizes the virus, whereas decreased severity of disease and decreased ability to transmit virus to contacts are related to antibody directed against the NA. Antibodies against ribonucleoprotein are type-specific and are useful in typing viral isolates as in influenza A and B. The three types of influenza viruses are antigenically unrelated and therefore induce no cross-protection. Antibodies appear in about 7 days after the attack and reach a maximum level in about 2 weeks. After 8 to 12 months, the antibody level drops to pre-infection level.

9. ENVIRONMENT FACTORS: Season: Winter months in northern hemisphere Tropical areas: Throughout the year Overcrowding: Enhance transmission. 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: 18 to 72 hours.

10. PATHOGENESIS AND CLINICAL FEATURE: The virus enters the respiratory tract and causes inflammation and necrosis of superficial epithelium of the tracheal and bronchial mucosa, followed by secondary bacterial invasion. There is no viraemia. SYMPTOMS: fever last for 1 to 5 days (average 3 days in adult) chills aches and pains, coughing generalized weakness.

11. DEADLY COMPLICATION:PNEUMONIA. REYE’S SYNDROME:(fatty liver with encephalopathy ) is a rare and severe complication of influenza, usually B type, particularly in young children. It consists of rapidly progressive hepatic failure and encephalopathy, and there is about 30 per cent mortality rate.

12. AVIAN FLU(BIRD FLU): Avian influenza refers to a large group of different influenza viruses that primarily affect birds. On rare occasions, these bird viruses can infect other species, including pigs and humans. The vast majority of avian influenza viruses do not infect humans. However, avian HsN1 is a strain with pandemic potential, since it might ultimately adapt into a strain that is contagious among humans. TRANSMISSION: Primarily acquired infection through direct contact with infected live or dead poultry bird or contaminated environments such as live bird market.

13. INCUBATION PERIOD: DIAGNOSIS: 2-5 days Confirmed by RT-PCR. TREATMENT: Antiviral drugs like zanamivir, oseltamivir. PREVENTION: Hand wash, Proper personal hygiene. Avoid touching eyes, nose and mouth when contact with sick people. VACCINE: It is inactivated influenza vaccine given two doses 28 days apart. The recipient can have pain and tenderness at the site of injection, head ache, muscle pain, general ill ness.

14. PANDEMIC INFLUENZA: (H1N1) 2009 (SWINE FLU) The pandemic influenza A (H!N1) 2009 virus differs in its pathogenicity from seasonal influenza in two key aspects. First, as the majority of human population has little or no pre-existing immunity to the virus, the impact of the infection has been in a wider age range, in particular among children and young adults. Secondly, the virus can infect the lower respiratory tract and can cause rapidly progressive pneumonia, especially in children and young to middle-aged adults. Incubation period: The incubation period appears to be approximately 2-3 days, but could range up to 7 days.

15. CLINICAL FEATURES: A wide clinical spectrum of disease ranging from nonfebrile mild upper respiratory illness, febrile influenza like illness (Ili), to severe or even fatal complications including rapidly progressive pneumonia. The case fatality rate is similar to seasonal influenza i.e. about 0.5 per cent; however this could change. (a) Uncomplicated influenza symptoms include : fever, cough, sore throat, rhinorrhea, headache, muscle pain, and malaise, but no shortness of breath and no dyspnea. Patients may present with some or all of these symptoms. Gastrointestinal illness may also be present, such as diarrhea and/or vomiting, especially in children, but without evidence of dehydration.

16. (b) Complicated or severe influenza : Presenting clinical (e.g. shortness of breath/ dyspnea, tachypnea, hypoxia) and/or radiological signs of lower respiratory tract disease (e.g. pneumonia), central nervous system (CNS) involvement (e.g. encephalopathy, encephalitis), severe dehydration, or presenting secondary complications, such as renal failure , multiorgan failure, and septic shock Other complications can include rhabdomyolysis and myocarditis. Exacerbation of underlying chronic disease, including asthma, COPD, chronic hepatic or renal failure , diabetes, or other cardiovascular conditions. (3) Any other condition or clinical presentation requiring hospital admission for clinical management. (4) Any of the signs of progressive disease.

17. SIGNS AND SYMPTOMS: (a) Symptoms and signs suggesting oxygen impairment or cardiopulmonary insufficiency : - Shortness of breath (with activity or at rest), difficulty in breathing, turning blue, bloody or colored sputum, chest pain, and low blood pressure; - In children, fast or labored breathing; and - Hypoxia, as indicated by pulse oximetry. (b) Symptoms and signs suggesting CNS complications: - Altered mental status, unconsciousness, drowsiness, or difficult to awaken and recurring or persistent convulsions (seizures), confusion , severe weakness, or paralysis.

18. RISK FACTORS: Infants and young children, in particular <2years Pregnant women Persons of any age with chronic pulmonary disease (e.g. asthma, COPD) Persons of any age with chronic cardiac disease (e.g. congestive cardiac failure) Persons with metabolic disorders (e.g. diabetes) Persons with chronic renal disease, chronic hepatic disease, certain neurological conditions (including neuromuscular, neurocognitive, and seizure disorders), haemoglobinopathies, or immunosuppression, whether due to primary immunosuppressive conditions, such as HIV infection, or secondary conditions, such as immunosuppressive medication or malignancy Children receiving chronic aspirin therapy Persons aged 65 years and older.

19. LABARATORY DIAGNOSIS: Reverse transcriptase polymerase chain reaction (RT- PCR) will provide the most timely and sensitive detection of the infection. CLINICAL FEATURES: Clinical specimens to be collected for laboratory diagnosis are respiratory samples. Samples from the upper respiratory tract, including a combination of nasal or nasopharyngeal samples, and a throat swab are advised. Recent evidence supports viral replication and recovery of pandemic A (H1 N 1) 2009 virus from lower respiratory tract samples (tracheal and bronchial aspirates) in patients presenting lower respiratory tract symptoms and in these patients, such samples have higher diagnostic yields than samples from the upper respiratory tract.

20. INFECTION CONTROL: Appropriate infection control measures (standard plus droplet precautions) should be adhered to at all times, which includes strict adherence to hand hygiene with soap and water or an alcohol based hand sanitizer, and to cover mouth and nose with tissue or handkerchief when coughing or sneezing. If ill persons must go into the community e.g. to seek medical care, they should wear a face mask to reduce the risk of spreading the virus in the community. The duration of isolation precautions for hospitalized patients with influenza symptoms should be continued for 7 days after onset of illness or 24 hours after the resolution of fever and respiratory symptoms, whichever is longer, while a patient is in a health-care facility

21. VACCINE: 3 different influenza technology in uses to produce vaccine: Egg based Cell culture type Recombinant technology INACTIVATED INFLUENA VACCINE: Trivalent IIV(Inactivated Influenza Vaccine) TYPE A (HIN1) TYPE A (H3N2) TYPE B Quadrivalent influenza virus were introduced in the year 2013-2014 They contain same antigen as the trivalent vaccine with addition of another B strain virus.

22. Route of administration: Intra-muscular, Intra dermal. Vaccine available in both pediatric (0.25 ml), Adult(0.5 ml). One dose of IIV may be administered annually for person 9 years of age and older. Children 6 month through 8 years of age receiving influenza vaccine for first time should receive 2 dose administrated atleast 28 days apart. Vaccine effective after 14 days. Immunity last for 6 to 2 months. Vaccine is 50 to 60% effective in preventing hospitalization 80 % in preventing death. Vaccine should be stored at temperature of 2 to 8 degree celcius .

23. SIDE EFFECTS: Inactivated vaccines, administered by injection, commonly cause local reactions such as soreness, swelling and redness at the injection site, and less often can cause fever, muscle or joint-aches or headache. These symptoms are generally mild and do not need medical attention, and last for 1-2 days. Fever, aches and headaches can occur more frequently in children compared to elderly people.

24. LIVE ATTENUATED VACCINE Live attenuated vaccines are given uia a nasal spray, and can commonly cause runny nose, nasal congestion, cough and can less frequently cause sore throat, low grade fever, irritability and muscle-aches and headache. Wheezing and vomiting episodes have been described in children receiving live influenza vaccines

25. Standard antiviral treatment regimens: Oseltamivir: Oseltamivir is indicated for treatment of influenza. For adults the recommended oral dose is 75 mg oseltamivir twice daily for 5 days. For infants less than 1 year of age recommended oral doses are as follows: >3 months to 12 months 3 mg/kg, twice daily for 5 days > 1 month to 3 months 2.5 mg/kg, twice daily for 5 days 0 to 1 month• 2 mg/kg, twice daily for 5 days

26. For older children the recommended oral doses according to body weight are as follows: 15 kg or less 30 mg twice a day for 5 days 15-23 kg 45 mg twice a day for 5 days 24-40 kg 60 mg twice a day for 5 days > 40 kg 75 mg twice a day for 5 day Zanamivir; Zanamivir is indicated for treatment of influenza in adults and children (>5 years). The recommended dose for treatment of adults and children from the age of 5 years is two inhalations (2 x 5 mg) twice daily for 5 days.

27. RUBELLA(GERMAN MEASLES) Rubella or german measles is an acute childhood infection, usually mild, of short duration (approximately 3 days) and accompanied by low-grade fever, lymphadenopathy and a maculopapular rash. Infection in early pregnancy may result in serious congenital defects, including death of the foetus . Epidemiological determinants: Agent factors (a) AGENT : Rubella is caused by an RNA virus of the togavirus family. Only one antigenic type of the virus seems to exist. The virus has been recovered from the nasopharynx, throat, blood, CSF and urine. It can be propagated in cell culture.

28. (b) SOURCE OF INFECTION : Clinical or subclinical cases of rubella. A large number of rubella infections are , in fact, subclinical. (c) PERIOD OF COMMUNICABILITY: Rubella is much less communicable than measles, probably because of the absence of coughing in rubella. It is difficult to state the exact period of infectivity. It probably extends from a week before symptoms to about a week after rash appears. Infectivity is greatest 1- 5 days after the appearance of rash HOST FACTOR AGE: Mainly disease of childhood particularly 3to 10 year

29. Environmental factors: Disease usually occurs in seasonal patters winter and spring . TRANSMISSION : Transmission: from person to person by droplets from nose and throat INCUBATION PERIOD: 2 TO 3 Weeks average days .

30. CLINICAL FEATURES: In a typical case, the clinical features comprise the following: (a) PRODROMAL : The prodromal symptoms (coryza, sore throat, low- grade fever) herald the onset of viraemia. They are generally mild and insignificant, and less frequent in children. (b) LYMPHADENOPATHY : In susceptible individuals, the enlargement of the postauricular and posterior cervical lymph nodes appears as early as 7 days before the appearance of the rash. This, however, is not pathognomonic since cases of clinical rubella without enlargement of lymph nodes have been documented. (c) RASH: The rash is often the first indication of the disease in children. It appears first on the face , usually within 24 hours of the onset of prodromal symptoms. It is a minute, discrete, pinkish, macular rash and not confluent as the rash of measles. Conjunctivitis may occur. COMPLICATIONS : In rare instances arthralgia may occur in several joints in adults, especially young women. Encephalitis is very rare. Thrombocytopenic purpura has also been observed as a complication.

31. DIAGNOSIS : A definitive diagnosis of rubella is possible only through virus isolation and serology. Throat swabs should be cultured for virus isolation; it takes longer than serological diagnosis. The haemagglutination inhibition (HI) test is a standard serological test for rubella ELISA tests are preferred because serum pretreatment is not required and they can be adapted to detect specific lgM Detection of lgG is evidence of immunity because there is only one serotype of rubella virus. To accurately confirm a recent rubella infection, either a rise in antibody titer must be demonstrated between two serum samples taken at least 10 days apart or rubella-specific lgM must be detected in a single specimen.

32. CONGENITAL RUBELLA Congenital rubella syndrome (CRS) refers to infants born with defects secondary to intrauterine infection or who manifest symptoms or signs of intrauterine infection sometime after birth Congenital infection is considered to have occurred if the infant has lgM rubella antibodies shortly after birth (as lgM antibodies do not cross the placenta, their presence indicate that they must have been synthesized by the infant in utero) or if lgG antibodies persist for more than 6 months, by which time maternally derived antibodies would have disappeared. Rubella infection inhibits cell division , and this is probably the reason for congenital malformations and low birth weight deafness cardiac malformations cataracts CLASSICAL TRIAD

33. PREVENTION: Active immunization against rubella is now possible with live attenuated vaccines RUBELLA VACCINES: RA 27/3 vaccine is administered in a single dose of 0.5 ml subcutaneously. It may provoke mild reactions in some subjects such as malaise, fever, mild rash and transient arthralgia, but no serious disability There is no evidence in favour of the administration of second dose unless first vaccinated below the age of 12 months Infants under one year should not be vaccinated due to possible interference from persisting rubella antibody. Pregnancy is considered a contraindication to rubella immunization. The recipients of the vaccine should be advised not to become pregnant over the next 3 months. Rubella vaccine is also available as combined measles, mumps and rubella (MMR) vaccine , or measles and rubella (MR). They are equally effective.

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