مجلات علمية
Influenza 1996 I Strains I Ways of prevention I Vaccination
Waves of influenza1996 occur throughout the year in winter months causing significant morbidity and mortality rate in the United States and affect people with high risk mostly.
Influenza 1996 caused infections including an average of approximately 114,000 hospital visitors and 20,000 deaths per year.
The most affected by Influenza1996:
Annual vaccination is a must for people at high risk, including :
1. Adults over 50 years,
2. Persons with chronic diseases such as :
.Heart disease.
.Pulmonary disease.
3. People with certain metabolic conditions.
4. Women in the second or third trimester of pregnancy were mainly affected by 1996.
During influenza1996 epidemics, morbidity rates among older adults and persons with chronic diseases increased from 2 to 5 times over non-epidemic times. Influenza 1996 epidemiology is related to increased mortality.
Time of occurrence:
Influenza1996 epidemics occur every year through the winter months and cause substantial morbidity and mortality in the United States, including an average of approximately 114,000 hospital visitors and make deaths to 20,000 in the year.
Reporting Period:
This report contains data about U.S. influenza surveillance from the time between October 1994 to May 1997, from both active and passive surveillance systems.
Description of System:
During this period CDC received weekly reports that include:
1) State and regional epidemiologists on the estimation of local influenza activity.
2) About 140 guardian physicians on their visits from patients and the number of cases of influenza-like illness (ILI).
3) About 70 World Health Organization (WHO) co-operating laboratories in the United States on influenza virus solutions per week. These laboratories also provided influenza1996 isolates to CDC for antigenic analysis. Throughout the year, vital statistics offices in 121 cities give reports about deaths due to pneumonia and influenza per week, providing a measure of the effect of influenza on the mortality rate.
Results:
1. During the influenza season through the year between 1994 to1995, 25 state epidemiologists give reports about local or world widespread activity at the top of the winter season. Observer doctors gave reports for cases of Influenza-Like Illness by exceeding baseline levels for 4 weeks, reaching a peak at 5%. Influenza A(H3N2) was the most isolated virus type. The longest period of continuous mortality was 5 successive weeks, when the mortality rate from Pneumonia and Influenza exceeded the epidemic threshold, peaking at 7.6%.
2. At the influenza1996 season, 33 state epidemiologists reported regional or widespread activity at the peak of the season. Influenza-Like Illness cases exceeded baseline levels for 5 weeks, peaking at 7%. Influenza A(H1N1) viruses predominated, although influenza A(H3N2) and influenza B viruses also were identified throughout the United States. P&I mortality exceeded the epidemic threshold for 6 consecutive weeks, peaking at 8.2%.
3)The season of influenza 1996 to 1997 was the maximum level severe of Influenza due to: (a)39 state epidemiologists gave reports containing local or widespread activity at the peak of the season of influenza.
(b)Influenza-Like Illness reports exceeded borderline levels for 5 successive weeks and reached the top at 7%. The percentage of respiratory specimens positive for influenza peaked at 34%, with influenza A(H3N2) viruses. (c)Influenza B viruses were found in the United States, but only one influenza A(H1N1) virus isolate was reported overall. The mortality rate due to Pneumonia and Influenza exceeded the epidemic threshold for 10 successive weeks, reaching a peak of 9.1%.
Explanation:
Influenza A(H1N1), A(H3N2), and B viruses spread during 1994--1997. Local monitoring data are important because of geographic and transient variations in the spread of influenza types/subtypes.
Actions for Public Health:
conducts active national surveillance annually from October through May for influenza 1996 to detect the emergence and spread of influenza virus variants and monitor the impact of influenza-related morbidity and mortality. Giving data every week throughout the influenza season to WHO and health care providers can be used to make prevention and control activities, vaccine strain selection, and patient care.
Influenza 1996 Activity Worldwide
Influenza activity in Europe, Asia, and North America was associated with influenza A(H1N1) and influenza A(H3N2) viruses.
.Japan, Canada:
There is Influenza A(H1N1).
.China, some regions of the U.S. & most European countries:
There is Influenza A(H3N2).
.most of the world:
Influenza B viruses were isolated.
Africa:
There is influenza A(H1N1) in Durban, South Africa between workers.
Influenza A(H3N2) viruses in Senegal and Madagascar and South Africa.
Asia:
Influenza A(H3N2) viruses, but influenza A(H1N1) and influenza B viruses also were identified.
Korea:
There are influenza A(H3N2) and influenza B viruses.
China:
There are influenza A(H3N2), influenza A(H1N1), and influenza B viruses.
southern China,
Outbreaks by influenza A(H3N2) viruses occurred in Guangzhou Province.
Hong Kong
Influenza A(H1N1), influenza B viruses, and influenza A(H3N2) were found.
Taiwan and Guam
Influenza A(H3N2) and influenza B viruses were isolated.
Croatia, Germany, and the United Kingdom influenza A(H1N1) was found.
Germany and Iceland
influenza A(H3N2) was found.
Canada
influenza A and influenza B viruses were found.
The influenza vaccination:
Influenza 1996 vaccine is updated every year to affect all strains of viruses that antigenically resemble the Influenza strains. The influenza vaccine for influenza 1996 season contains:
1.A/Texas/36/91-like (H1N1). 2.A/Wuhan/359/95-like (H3N2).
3.B/Beijing/184/93-like antigens.
4. A/Wuhan/359/95-like antigens. 5.B/Beijing/184/93-like antigens.
U.S. manufacturers will use the antigenically equal strains A/Nanchang/933/95(H3N2) and B/Harbin/07/94 viruses, respectively, because of their growth properties. Since March 1996, most influenza 1996 viruses isolated worldwide have been antigenically similar to the vaccine strains.
Role of Influenza 1996 vaccination:
1. Vaccination of persons at high risk for influenza is a must way to reduce the effect of influenza.
2. Vaccination of persons in continuous contact with persons at high risk to reduce transmission of infection. 3. Influenza 1896 vaccination is effective 70%--90% in preventing influenza-like illness (ILI) in young, healthy adults.
4. Influenza1996 viruses have continual antigenic changes.
The influenza1996 vaccine
It contains 1.A/Texas/36/91(H1N1). 2.A/Johannesburg/33/94(H3N2).
3. B/Beijing/184/93-like antigens.
4. For the B/Beijing/184/93-like virus, U.S. vaccine manufacturers used the antigenically equivalent virus B/Harbin/07/94 because of its growth properties.
Summary
Influenza1996 made losses in many countries and worldwide but. By vaccination, it comes under control.
