Treatment and Prevention for Influenza

There is no specific cure for influenza. Recommended treatment usually consists of bed rest and increased intake of nonalcoholic fluids until fever and other symptoms lessen in severity. Certain drugs have been found effective in lessening flu symptoms, but medical efforts against the disease focus chiefly on prevention by means of vaccines that create immunity.

Drugs That Ease Symptoms
Vaccines

Pandemics and Historic Outbreaks

Evidence suggests that all influenza viruses in mammals, including humans, derived from viruses in wild ducks and other waterfowl. Some of these viruses could have been acquired by humans thousands of years ago. But medical historians know of no clearly identifiable influenza epidemics until large-scale outbreaks occurred in Europe in 1510, 1557, and 1580. The 1580 outbreak also spread into Africa and Asia, making it the first known pandemic. Pandemics have occurred periodically ever since. Major pandemics took place in 1729-1730, 1732-1733, 1781-1782, 1830-1831, 1833, and 1889-1890. The last of these, called the Russian flu because it reached Europe from the east, was the first pandemic for which detailed records are available.

In the 20th century, major pandemics occurred in 1918-1919, 1957-1958, and 1968-1969. The 1918-1919 pandemic was the most destructive in recorded history. It started as World War I (1914-1918) was ending and caused 20 million deaths—twice as many deaths as the war itself. When and where the pandemic began is uncertain, but because Spain experienced the first major outbreak, the disease came to be called the Spanish flu. The virus was exceptionally lethal; many of the deaths were among young adults age 20 to 40, a group usually not severely affected by influenza.

In 1957 a flu outbreak occurred in Guizhou, a province in southwestern China. Within six months, most areas of the world were battling what became known as Asian flu. Before the 1957-1958 pandemic subsided, an estimated 10 to 35 percent of the world’s population had been affected. The overall mortality rate, however, was comparatively low.

About a decade later, a variant of the virus that caused the 1957-1958 pandemic originated in either Guizhou or Yunnan province in southern China. The variant was first isolated and identified in Hong Kong in July 1968. Within a few months, cases of this Hong Kong flu appeared around the world. Hardest hit by the pandemic were children under age 5 and adults aged 45 to 64. In the United States, an estimated 30 million people were infected and there were some 33,000 influenza-related deaths.

No additional pandemics occurred during the 20th century, but public health experts expect that there will be more pandemics in coming years. While scientists do not yet know how to accurately predict flu outbreaks, they have established an international network to track and monitor outbreaks so that health officials can take immediate preventive measures to avoid pandemics. The international network, called FluNet, consists of about 110 influenza centers in more than 80 countries and several World Health Organization (WHO) centers, all linked electronically.

Influenza Research

By the late 1890s and early 1900s, scientists understood that microorganisms caused disease. Most disease research focused on bacteria, which are large enough to be visible under a light microscope and can be isolated using filters. But technology at the time prevented scientists from identifying a disease-causing agent as small as a virus.

In the 1890s German bacteriologist Richard F. J. Pfeiffer reported that he had identified the bacterium Haemophilus influenzae as the cause of influenza. Further investigation indicated, however, that this bacterium was not always present in people with influenza. Scientists concluded that the Haemophilus influenzae bacterium probably played a role in secondary infections.

Meanwhile, the long-held belief that influenza only occurred in humans was overturned. Around 1930 American bacteriologist Richard E. Shope showed that it was possible to transfer an influenza-like disease from one pig to another. Thereafter scientists chiefly used animals in their research on influenza.

In 1933 English physicians Wilson Smith, Christopher H. Andrewes, and Patrick P. Laidlaw removed secretions from the throat of a human flu victim, filtered out a suspect infectious agent, and injected the material into ferrets. The ferrets then developed influenza, thereby demonstrating that the infectious agent caused influenza. Research performed by other researchers eventually proved that the infectious agent was the influenza A virus. The influenza B virus was isolated in 1940, and the influenza C virus in 1950.

In 1941 scientists demonstrated that a vaccine could control influenza. The first vaccine was developed to protect soldiers during World War II (1939-1945). Early influenza vaccines produced from the 1940s to the mid-1960s were all made from killed viruses, which cannot cause infection. But these early vaccines contained impurities that produced fever, headaches, and other severe side effects. Improved pharmaceutical procedures have made today’s vaccines almost free from impurities, greatly reducing the chance that the vaccines will cause side effects.

Despite these improvements, developing influenza vaccines remains a challenge. Current vaccines do not provide 100 percent protection against influenza, and they can be quickly rendered ineffective by changes in the viruses themselves. Some scientists, believing that vaccines will never be able to completely control influenza, work to expand the number and variety of drugs available to treat the disease once symptoms appear. Until a cure for influenza is discovered, public health officials hope that identifying and reporting new viral strains quickly will result in timely actions that prevent the recurrence of deadly pandemics. Even in best-case scenarios, however, influenza is expected to remain a formidable opponent of human health.

Entrepreneur

Entrepreneur, one who assumes the responsibility and the risk for a business operation with the expectation of making a profit. The entrepreneur generally decides on the product, acquires the facilities, and brings together the labor force, capital, and production materials. If the business succeeds, the entrepreneur reaps the reward of profits; if it fails, he or she takes the loss.

The Austrian-American economist Joseph A. Schumpeter stressed the role of the entrepreneur as an innovator, the person who develops a new product, a new market, or a new means of production. One important example was Henry Ford. In the industrialized economies of the late 20th century, giant corporations and conglomerates have largely replaced the individual owner-operator. There is still a place for the entrepreneur, however, in small businesses as well as in the developing economies of the Third World nations.

NEW DIRECTIONS IN WEIGHT CONTROL

The weight-loss goal of most obese dieters is to achieve an ideal weight often defined by celebrities and models in fashion magazines. But research over the last decade indicates that a 5- to 10-percent reduction in body weight is sufficient to significantly improve medical conditions associated with obesity, such as hypertension, diabetes mellitus, and elevated cholesterol levels. These health improvements occur even though patients may still be overweight.
These new weight-loss goals may be difficult for obese people to accept. Obese people often seek weight-loss goals that may be biologically impossible to achieve or, if achieved, cannot be maintained. One study of overweight women found that the average weight goal was a 30 percent reduction in body weight. Yet no obesity treatment produces long-term, maintainable weight losses significant enough for patients to reach this goal. Physicians and commercial weight-loss programs need to help obese people feel successful when more modest reductions in weight and significant improvements in health are achieved, many health experts believe.

OBESITY

OBESITY, medical condition characterized by storage of excess body fat. The human body naturally stores fat tissue under the skin and around organs and joints. Fat is critical for good health because it is a source of energy when the body lacks the energy necessary to sustain life processes, and it provides insulation and protection for internal organs. But the accumulation of too much fat in the body is associated with a variety of health problems. Studies show that individuals who are overweight or obese run a greater risk of developing diabetes mellitus, hypertension, coronary heart disease, stroke, arthritis, and some forms of cancer.

MEASURING OBESITY

The body mass index (BMI) is commonly used to determine desirable body weights. BMI is a measure of an adult’s weight in relation to height, and it is calculated metrically as weight divided by height squared (kg/m2). People with a BMI of 25.0 to 29.9 are considered overweight and people with a BMI of 30 or above are considered obese .

Body mass index only provides a rough estimate of desirable weight, however. Physicians recognize that many other factors besides height affect weight. Weight alone may not be an indicator of fat, as in the case of a bodybuilder who may have a high BMI because of a high percentage of muscle tissue, which weighs more than fat. Likewise, a person with a sedentary lifestyle may be within a desirable weight range but have excess fat tissue. In general, however, the higher the BMI, the greater the risk for developing serious medical conditions.

CAUSES OF OBESITY

A calorie is the unit used to measure the energy value of food and the energy used by the body to maintain normal functions. When the calories from food intake equal the calories of energy the body uses, weight remains constant. But when a person consumes more calories than the body needs, the body stores those additional calories as fat, causing subsequent weight gain. Consuming about 3,500 calories more than what the body needs results in a weight gain of 0.45 kg (1 lb) of fat.

TREATMENTS FOR OBESITY

Obesity can become a chronic lifelong condition caused by overeating, physical inactivity, and even genetic makeup. No matter what the cause, however, obesity can be prevented or managed with a combination of diet, exercise, behavior modification, and in severe cases, weight-loss medications and surgery.

Diets

The most common and conservative treatment for obesity utilizes a nutritionally balanced, low calorie diet. Most health-care professionals and commercial weight-loss programs recommend diets consisting of 1,200 to 1,500 calories per day, usually in the following proportions: 60 percent carbohydrate, 30 percent fat, and 10 percent protein. Research from university obesity treatment centers indicates that patients who follow a low calorie diet lose 10 percent of their initial weight in 20 weeks. Without further treatment, however, patients usually regain one-third of the weight in the following year.

A more aggressive approach for persons who are more than 20 kg (40 lb) overweight includes very low calorie diets ranging from 400 to 800 calories per day. These diets are usually based on four to five servings of a liquid formula each day. Candidates must be carefully screened and medically supervised while on the diet. People on very low calorie diets lose approximately 15 to 20 percent of their initial body weight in 16 weeks. Once they go off a very low calorie diet, they typically regain approximately one-half of that weight within a year.

Meal replacements are liquid shakes or portion-controlled meals that are substituted for one or two meals a day. They are typically used as part of a 1,200 to 1,500 calorie diet. Studies have shown that meal replacements are often more effective than very low calories diets, resulting in an increase in the amount of initial weight loss and enabling dieters to maintain their weight loss. Unlike very low calorie diets, meal replacements do not require that candidates receive extensive medical monitoring.

Exercise

Caloric restriction alone will not produce long-term weight loss. While the data from studies on the effect of exercise for short-term weight loss are contradictory, research clearly indicates that regular exercise is the single best predictor for achieving long-term weight control. Regular exercise will also improve some of the medical conditions associated with obesity, including elevated blood cholesterol, hypertension, and diabetes mellitus.