16 INFLUENZA VACCINE
Influenza is an infectious disease of the respiratory tract spreading among a wide range of ages from infants to the old. The Japanese vaccination policy against this has two aspects, mass and individual protection; control of social influenza by practicing mass vaccination to pupils of elementary and junior high schools and students of senior high schools and for the individuals in the groups of school children and students who are vaccinated to immune to infection.
The first vaccination in Japan started in 1957, when Asian type (H2N2) virus emerged. In 1962, the mass vaccination system was adopted officially. New-type influenza HA-vaccine, causing less side reaction by removing the lipid component by ether treatment and can safely be used for children has been used since 1972. HA stands for hemagglutinin. HA vaccine contains all the seven protein components other than that construct HA the virus.
Mass vaccination requiring the parents' consent has been practiced in a way close to optional. The rate of effectiveness of the vaccine is estimated at about 80% the rate varies largely depending on the mutation of the epidemic viruses. Vaccination to such cases with such complication a pneumonia, and with such basal diseases as heart disease, diseases of the respiratory tract, diabetic and renal disease, and the olderly can be recommended also in the optional form.
A. OUTLINE OF THE DISEASE
16.1 Clinical Features and Diagnosis
16.1.1 Clinical features
Influenza infection starts from inhalation of droplet nuclei derived from patients through sneeze and sputum. The incubation period varies from one to five days depending upon the dose of virus inhaled, the invading site and the level of the virus proliferated. The most common incubation period is 2 days, which correspond to the period corresponding to 4 to 5 generations of 8 hours/generation. After the incubation period, systemic and local symptoms emerge. The former include fever, as the major one, and headache, general weakness, feeling of discoordination, Iumbago, melosalgia and arthralgia. Symptoms of the respiratory system representing the lather appear often a day or two later, characterized by sneeze, pharyngalgia nose stuffing, and cough. In addition to these respiratory symptoms, mild symptoms of the digestive tract are often accompanied such as anorexia, vomiting, gastroenteritis, abdominalgia, and diarrhea. The prognosis is usually good, and patients recover within a week. If the disease worsen, various complications as shown in Table 16.1 are induced.
16.1.2 Pathology
The severity and spread of the symptoms of influenza reflect the injury of the cells, tissues or organs. They are subcutaneous necrosis of the pharynx and bronchus. congestion of the lamina propria and plasma cell infiltration of the surroundings, degeneration of the respiratory epithelial cells and toxic myocarditis. The fatal cases are often due to mixed infection with Staphylococcus aureus, beta-hemolytic Streptococcus faecalis, Haemophilus influenza. ....................