PUBLIC HEALTH SIGNIFICANCE SEASONAL INFLUENZA AVIAN INFLUENZA SWINE INFLUENZA

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1 INFLUENZA DEFINITION Influenza is an acute highly infectious viral disease characterized by fever, general and respiratory tract catarrhal manifestations. Influenza has 3 Types Seasonal Influenza Avian Influenza : an infectious viral disease of birds. Some of avian influenza viruses can cause infections (clinical or subclinical) in humans and other mammals. Swine Influenza: an infectious viral disease of pigs by any one of several types of swine influenza virus. PUBLIC HEALTH SIGNIFICANCE Occurs as sporadic cases, outbreaks, epidemics, and pandemics (3 in the last century). During epidemics, clinical attack rates is 10-20% in general population and more than 50% in closed population. Influenza epidemics evolve rapidly, spread widely with serious complications and death especially in elderly and patients with chronic debilitated diseases. 1- All birds are susceptible to infection with avian influenza viruses. 2- Many wild birds especially ducks and geese carry the viruses with no harm. 3- It can spread to domestic poultry causing serious outbreaks. 4- Virus A (H5N1) subtype, 1 st infected humans in 1997 during poultry outbreak in Hong Kong. 5- H5N1 re-emerged in 2003, spread from Asia to Europe & Africa (pandemic) and resulting in millions of poultry infections, hundreds of human cases and many human deaths. 6- In Egypt, the 1 st direct bird-to-human spread of (H5N1) occurred in The total number of cases in 2009 was 85 with 27 deaths with case fatality rate is 31.7% 7- Globally, case fatality rate reached 50% mostly due to respiratory complications. Influenza virus is (RNA) virus that have 3 types; Type A: associated with epidemics and pandemics. Type B: is associated with regional or widespread epidemics. Type C: is associated with sporadic cases and minor localized outbreaks. Influenza virus has 2 surface antigens: Swine influenza virus is common in pigs and its transmission to humans is not common. In April 2009, WHO, declared a "public health emergency of international concern" when 2 cases of H1N1 virus were reported in USA, followed by hundreds of cases in Mexico. Many countries starting vaccination campaigns. In April 2010, worldwide, 17,700 deaths were attributed to the virus. Risk factors were extremities of age, pregnant females and individuals with systemic diseases. In Egypt, total number was 808 cases with 2 deaths (case fatality rate 0.2%). In August 2010, WHO declared that swine flu pandemic is officially over CAUSATIVE AGENT Influenza viruses type A (H5N1) is the cause of current pandemic. It survives in low temperature. Influenza viruses type A But killed at 70C, by alcohol, vinegar and (H1N1) subtype. normal disinfectants.

2 RESERVOIR EXIT OF VIRUS PERIOD OF INFECTIVITY INCUBATION PERIOD Human (typical or a typical cases): the main reservoir. Birds (wild & domestic). Human cases Animal: swine & avian reservoir. Pigs. Pigs. The virus find exit via nasopharyngeal secretions. Nasopharyngeal discharges, lacrimal discharges, stool and blood. 3-5 days after clinical onset in adult up to 7 days in 1 day before up to 7 days after young children. becoming sick. 1-3 days Internationally 7 days. Internationally 7 days MODES OF TRANSMISSION 1- Animal to animal infection: Direct contact of susceptible animal to secretions (saliva, nasopharyngeal, feces or blood) of infected animals (ducks, chicken, pigs, whales, horses and seals). 1- Direct droplet infection 2- Air-borne infection: by droplet nuclei and contaminated dust in closed places (virus survives for hours in dried mucus particularly in cold and dry environment). 3- Freshly contaminated articles & fomites with nasopharyngeal discharges. 4- Nasal inoculation after hand contamination with the virus. It can occur as sub-clinical and clinical cases which may be mild, moderate or severe form. It is a self limited disease with acute fever, sore throat, headache, severe cough, myalgia, prostration and back pain. Recovery occur within 2-4 days. 2- Animal to human infection: Direct contact of humans with infected poultry, its discharges and feces. CLINICAL PICTURE 1- High fever, 2- Influenza-like symptoms. 3- Diarrhea, vomiting, abdominal pain. 4- Bleeding from the nose and gums. The same ways that seasonal flu spreads 1- Direct droplet infection 2- Air-borne infection: by droplet nuclei and contaminated dust. 3- Freshly contaminated articles & fomites with nasopharyngeal discharges. 4- Nasal inoculation after hand contamination with the virus. similar to the symptoms of seasonal human flu. Some people have reported also diarrhea and vomiting.

3 GENERAL PREVENTION General measures for prevention of droplet infections: [1] General measures for prevention of droplet and contact infections. [2] Measures for patients with avian flu: Isolation: in fever hospital with standard precautions. 1- Sanitary environment: Nursing precautions: hand hygiene, gloves, gowns, eye protection, - Air sanitation, good disposable thermometers. ventilation and adequate Tamiflu: is the anti viral drug of choice. spacing. - Prevention of [3] Measures for health care workers: overcrowdings. Standard precautions. 2- Health education: educate the public about; - Mode of transmission. - Methods of protection and importance of immunization. 3- Health promotion: - Healthy life style including adequate nutrition. Surveillance. Vaccination with human influenza A vaccine to risk of co-infection with human and avian strain. [4] Measures during food preparation especially poultry: Hygienic Handling of raw poultry. Hand washing with soap & water after handling frozen or raw chicken or eggs. Cook all poultry & poultry products to a high temperature above 70. Eggs should not be consumed raw or partially cooked. [5] Live attenuated vaccines for poultry, Effect: Protect animals preventing mortality, but not affecting the carrier state. General measures for prevention of droplet infections: 1) In health education of the public: stress on the following: - Washing hands. - Avoid touching eyes, nose or mouth. - Avoid touching surfaces contaminated with the flu virus. - Healthy habits especially during cough and sneezing. 2) Measures for swine: - Culling- killing of infected and potentially infected animals - Quarantine: putting infected farms in quarantine. - Avoid live animal markets and pig farms in infected countries. - Cook pork thoroughly, although swine flu viruses do not infect orally. SWINE FLU VACCINES: Vaccination of at risk groups e.g. pilgrims. Immunization is less effective in preventing illness but it : Disease severity by 60% Complications by 50-60% Death by 80 % Ministry of health plan, 2007 for flu pandemic 1- Database for all available health care settings & all resources. 2- Labs for diagnosis of H1N1 virus: its number & quality. 3- Health education: through mass media (signs & symptoms, preventive measures). [3] AVIAN INFLUENZA Antigenic shift and danger of person to person transmission: If a pig is infected with both human influenza virus and avian influenza virus in the same time, mixing genes (Reassortment) can occur producing a new virus that may be able to infect humans and spread from person to person resulting in an influenza pandemic. 4- Vaccination of health care workers, according to a priority plan. 5- Strategic store of antiviral drugs & personal protective devices e.g. masks 6- Quarantine measures & sentinel surveillance e.g. at airports, fever hospitals.

4 [1] SEASONAL INFLUENZA COMPLICATIONS SUSCEPTIBILITY & RESISTANCE LABORATORY DIAGNOSIS 1- Secondary bacterial infection: Bronchitis. Bronchopneumonia. Otitis media. Gastro enteritis. 2- Children with salicylate therapy: may develop Reye disease, that involve the CNS and liver. Age: When a new subtype appears, all ages are susceptible. Immunity: Infection produces type-specific, transient immunity. Recurrent attacks occur due to continuous mutation, multiple strains, with no cross immunity between different strains. Vaccine produces specific immunity to the included virus. Environment: More in cold weather due to overcrowding & ill ventilation. Epidemics: usually in winter, but may occur all over the year. 1. Direct identification of viral antigen in nasopharyngeal cells by FA test or Eliza. 2. Rising titer of specific serum antibodies. NATURE DOSE PROTECTIVE VALUE INDICATIONS SPECIFIC PREVENTION INFLUENZA VACCINES CHEMOPROPHYLAXIS INACTIVATED TRIVALENT VACCINE LIVE ATTENUATED INTRANASAL VACCINE Admantadine HCL: Adults 200 mg and children100 mg, orally for 10 days. Killed vaccine containing 2 subtypes of A virus (H1N1 & H3N2), B strain & the currently circulating strains present in the locality. -Non-immunized: 2 doses, 4 weeks apart, 0.5 ml each, I.M. -Immunized before: a single dose is sufficient (should be given each year before influenza season, in late autumn & early winter). - Live attenuated vaccine, contains two subtypes A & B. - Heat sensitive that requires cold chain supervision. 0.5 ml by intranasal spraying. 80% against the circulating strain of the virus. It produces local & systemic immunity. 1- Health care workers. 2- Old aged persons above 65 years. 3- Immune-compromised patients. 4- Cases with chronic debilitating diseases. Only for healthy people aged 5 49 years. Remantadine HCL: Uses: chemoprophylaxis of influenza A but not B. Side effects: in 5-10 % of recipient (fever & CNS problems). Indication: high risk groups such as elderly, children & chronic disease. Contraindications: patient with CNS, neurological or psychological disorders.

5 [2] SWINE INFLUENZA DIAGNOSIS Possible case Probable case Confirmed case Clinical + Epidemiological criteria Clinical + Epidemiological criteria + Positive influenza rapid testing 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 CONTROL SEASONAL INFLUENZA SWINE INFLUENZA [A] CONTROL OF CASE Notification to local health office to local health office & WHO Isolation mostly impractical because of delayed diagnosis. in fever hospital & discharge after cure. Treatment Antibiotics to prevent secondary bacterial infections. Tamiflu is the anti-viral drug of choice. Antiviral (admantadine or remantadine) within 48 hours, for 3-5 days to symptoms and virus titer in respiratory secretion. Disinfection Concurrent (for articles). Terminal (for the place). Concurrent (for articles). Terminal (for the place). [B] CONTROL OF CONTACT 1- Surveillance: for the maximum incubation period. 2- Chemoprophylaxis: antiviral may be used in high risk contacts. [C] EPIDEMIC MEASURES Health education of the public, particularly high risk of the public through media, (mode of transmission & ways of preventions). Immunization high risk groups high risk groups. Surveillance the community. all airports and screening for any suspected cases. Adequate supplies antiviral drugs and vaccination. antiviral drugs and vaccination.