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Emerging diseases Emerging Diseases As we face the new millennium, we must renew our commitment to the prevention and control of infectious diseases, recognizing that the competition between humans and microbes will continue long past our lifetimes and those of our children.” Jeffrey P. Koplan, Director, CDC Institute of Medicine definition of emerging infections: New, reemerging or drug resistant infections whose incidence in humans has increased within the past two decades or whose incidence threatens to increase in the near future. Emerging Infectious Diseases Infectious diseases are a continuing danger to all people, no matter what their age, gender, lifestyle, ethnic background, or economic status. They are still one of the most common causes of suffering and death, and they impose an enormous financial burden on society. Some diseases have been effectively controlled with the help of modern technology such as antibiotics and vaccines. Yet new diseases—such as AIDS, Lyme disease, and hantavirus pulmonary syndrome—are constantly appearing. Others, such as malaria, tuberculosis, and bacterial pneumonias, are now appearing in forms that are resistant to drug treatments. West Nile virus Lyme Disease SARS Dengue fever Hantavirus Tuberculosis BSE (Mad Cow) Emerging diseases Antibiotic Resistance Where are Antibiotics Used 1. Human medicine - Antibiotics are used primarily in two different settings: as preventive medication and as treatment of a disease. Antibiotics are one of the most common medications prescribed in the United States (US). Approximately one out of seven prescriptions in the US is for an antibiotic. In 1994, there were over 100 million physician visits where antibiotics were prescribed for 4 common outpatient conditions (sinusitis, bronchitis, otitis, and pharyngitis). Another study found that 50-70% of visits for colds, URI, and bronchitis resulted in an antibiotic script. A New England Journal of Medicine article found that 30% of hospitalized patients are receiving antimicrobial medication. The true usage of antibiotics in developing countries is almost impossible to measure since many of these medications are available without a prescription and the reason they are being taken is not usually determined. 2. Animal medicine - As in human medicine, antibiotics are used for prevention of disease and treatment of illness. The selective pressure of antibiotic use is even stronger in animals since domestic animals outnumber humans 5 to 1. Other figures quoted are that 6 billion animals are raised annually for human consumption and most of these animals receive antibiotics during their lifetime. Farm animals receive 30 times more antibiotics than humans. 50% of all antibiotics produced are administered to farm animals. Milk can contain small concentrations of 80 different antibiotics. 3. Animal Husbandry - In the US, antibiotics have been used as growth promoters in the animal husbandry business since the 1950s. At that time it was shown that antibiotics in animal feed increased the weight for many different animals including chickens and cattle. This practice has been banned in several European countries due to the antibiotic resistance issue. However, no such ban exists in the United States. On the contrary, the animal husbandry business has now started to use quinolones as well. Several studies have shown that there is a strong correlation between antibiotic use and resistance occurrence. There is less information as to how much this practice in animal husbandry contributes to the overall antibiotic resistance problems in humans. 4. Treatment of Crop Disease - Antibiotics are used both for treatment of bacterial and fungal infections of crops, as well as prevention of these diseases. Factors in Misuse of Antibiotics in Human Medicine 1. Over prescribing of antibiotics by physicians and other allied health professionals: a large majority of antibiotics are written for common outpatient concerns many of which are caused by viruses, not bacteria. 2. Over usage and incomplete course of antibiotics by patients: many patients request antibiotics for the common outpatient conditions from their physicians. When appropriate antibiotics are given, patients may only take part of the course of antibiotic and not finish the remainder, possibly leaving a bacteria partially treated. Resistance can increase in these settings. 3. Over the counter availability of antibiotics: this is a big concern internationally where many antibiotics are available without prescriptions. Many pharmacists in these countries act as the Emerging diseases caregiver and give out antibiotics based on patients' complaints without adequate diagnosis or testing. 4. High cost and lack of adequate medications: many antibiotics are very expensive for several lesser-developed countries. This may contribute to only partial use of an antibiotic. For example, if only one drug is available for TB, it may be used as single therapy, which leads to significant resistant rates. WEST NILE VIRUS West Nile virus (WNV) is a potentially serious illness. Experts believe WNV is established as a seasonal epidemic in North America that flares up in the summer and continues into the fall. This fact sheet contains important information that can help you recognize and prevent West Nile virus. What Are the Symptoms of WNV? WNV affects the central nervous system. Symptoms vary. No Symptoms in Most People. Approximately 80 percent of people who are infected with WNV will not show any symptoms at all. Mild Symptoms in Some People. Up to 20 percent of the people who become infected will display mild symptoms, including fever, headache, and body aches, nausea, vomiting, and sometimes swollen lymph glands or a skin rash on the chest, stomach and back. Symptoms typically last a few days. Serious Symptoms in a Few People. About one in 150 people infected with WNV will develop severe illness. The severe symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. These symptoms may last several weeks, and neurological effects may be permanent. How Does It Spread? Infected Mosquitoes. Generally, WNV is spread by the bite of an infected mosquito. Mosquitoes are WNV carriers that become infected when they feed on infected birds. Infected mosquitoes can then spread WNV to humans and other animals when they bite. Transfusions, Transplants, and Mother-to-Child. In a very small number of cases, WNV also has spread through blood transfusions, organ transplants, breastfeeding and even during pregnancy from mother to baby. Not through touching. WNV is not spread through casual contact such as touching or kissing a person with the virus. Lyme Disease Lyme disease (Lyme borreliosis) is a bacterial infection spread by certain kinds of ticks. Lyme disease occurs in North America, Europe, and Asia. Lyme disease is the most common disease transmitted by arthropods (a type of insect) in the United States. In different parts of the United States, different kinds of ticks carry the bacteria that can cause Lyme disease. Deer ticks spread Lyme disease in the northeastern and upper midwestern United States. The ticks that spread Lyme disease are very small (about the size of a poppy seed or sesame seed), and their bite is usually painless. People usually don't know they have been bitten. Even in areas where Lyme disease occurs most often, only a few tick bites will lead to Lyme disease. Emerging diseases The risk of Lyme disease is highest during the spring, summer, and early fall months (May through August), when young (nymphal stage) ticks are most active and people spend more time outdoors. Early signs and symptoms, which often include an expanding skin rash and a flulike symptoms, usually appear during this time. If Lyme disease is diagnosed early, antibiotic treatment usually gets rid of the infection quickly and completely so that no further complications develop. If Lyme disease goes undetected or is not properly treated, problems involving the skin, joints, nervous system, and heart may develop weeks, months, or even years later. These problems usually improve after antibiotic treatment, but in rare cases the disease may cause permanent damage. Recent studies show that most people with Lyme disease who are diagnosed early and treated appropriately with antibiotics have no long-term disabilities resulting from the disease. SARS Severe acute respiratory syndrome (SARS) is a viral respiratory illness caused by a coronavirus, called SARS-associated coronavirus (SARS-CoV). SARS was first reported in Asia in February 2003. Over the next few months, the illness spread to more than two dozen countries in North America, South America, Europe, and Asia. The SARS global outbreak of 2003 was contained; however, it is possible that the disease could re-emerge. The SARS outbreak According to the World Health Organization (WHO), during the SARS outbreak of 2003, a total of 8,098 people worldwide became sick with SARS; of these, 774 died. In the United States, there were 192 cases of SARS among people, all of whom got better. Through July 2003, laboratory evidence of SARS-CoV infection had been detected in only eight U.S. cases. Most of the U.S. SARS cases were among travelers returning from other parts of the world with SARS. There were very few U.S. cases among close contacts of travelers, including health-care workers and family members. SARS did not spread more widely in the community in the United States. Symptoms of SARS In general, SARS begins with a high fever (temperature greater than 100.4°F [>38.0°C]). Other symptoms may include headache, an overall feeling of discomfort, and body aches. Some people also have mild respiratory symptoms at the outset. About 10 percent to 20 percent of patients have diarrhea. After 2 to 7 days, SARS patients may develop a dry cough. Most patients develop pneumonia. How SARS spreads The main way that SARS seems to spread is by close person-to-person contact. The virus that causes SARS is thought to be transmitted most readily by respiratory droplets (droplet spread) produced when an infected person coughs or sneezes. Droplet spread can happen when droplets from the cough or sneeze of an infected person are propelled a short distance (generally up to 3 feet) through the air and deposited on the mucous membranes of the mouth, nose, or eyes of persons who are nearby. The virus also can spread when a person touches a surface or object contaminated with infectious droplets and then touches his or her mouth, nose, or Emerging diseases eye(s). In addition, it is possible that the SARS virus might spread more broadly through the air (airborne spread) or by other ways that are not now known. dengue A painful viral disease that flourishes in tropical climates throughout the world. The virus that causes the disease is carried by Aedes mosquitoes. Because of the intense pain in the bones, dengue is known also as "breakbone fever" and by other names based on the necessity of keeping the neck rigid, such as "dandy" and "giraffe." People who have had dengue are generally immunized against the disease for 5 years, and epidemics tend to recur at 5-year intervals. Occasional epidemics occur in the Gulf states of the United States. SYMPTOMS. The symptoms of dengue begin within a week after the bite of the infected mosquito. The onset is marked by a severe headache and pain behind the eyes. Within hours the characteristic pain in the back and joints begins. Movement is difficult, and the temperature may rise as high as 41° C (106° F). A pink rash, congested eyeballs, and a flushed face are outward signs. The disease usually has two stages of about 3 days and 2 days separated by a period of 24 hours in which the symptoms disappear, raising hopes of the end of the attack. The second stage is marked by the earlier symptoms and in addition a red rash appears on the trunk and lower extremities, leading often to peeling skin. The total course of the disease is rarely more than 6 or 7 days. Although the sufferer is exhausted and less resistant to other diseases, dengue by itself is rarely fatal. Convalescence is slow. TREATMENT AND PREVENTION. As there is no known remedy for dengue, the treatment is mainly palliative. An icecap to reduce the headache, analgesics to relieve the pain, and a large intake of liquid are the basic essentials. Aspirin should be avoided to prevent problems associated with thrombocytopenia that often occurs with the disease. The best method of preventing dengue is by controlling the mosquito. TB TB, or tuberculosis, is a disease caused by bacteria called Mycobacterium tuberculosis. The bacteria can attack any part of your body, but they usually attack the lungs. TB disease was once the leading cause of death in the United States. In the 1940s, scientists discovered the first of several drugs now used to treat TB. As a result, TB slowly began to disappear in the United States. But TB has come back. Between 1985 and 1992, the number of TB cases increased. The country became complacent about TB and funding of TB programs was decreased. However, with increased funding and attention to the TB problem, we have had a steady decline in the number of persons with TB. But TB is still a problem; more than 16,000 cases were reported in 2000 in the United States. TB is spread through the air from one person to another. The bacteria are put into the air when a person with TB disease of the lungs or throat coughs or sneezes. People nearby may breathe in these bacteria and become infected. People who are infected with latent TB do not feel sick, do not have any symptoms, and cannot spread TB. But they may develop TB disease at some time in the future. People with TB disease can be treated and cured if they seek medical help. Even better, people who have latent TB infection but are not yet sick can take medicine so that they will never develop TB disease. Emerging diseases Hantavirus pulmonary syndrome Hantavirus pulmonary syndrome is a rare disease caused by a virus (hantavirus). The first symptoms of hantavirus pulmonary syndrome are fever, muscle pain, and being tired. This happens 1 to 3 weeks after a person is exposed to hantavirus. Some people also get headaches, dizziness, vomiting, or diarrhea. After about 4 to 10 days, people who are sick with hantavirus infection begin to cough and have shortness of breath. If someone is sick with hantavirus pulmonary syndrome and does not get help quickly, he or she may die. Can animals transmit hantavirus pulmonary syndrome to me? Yes, wild rodents can pass hantavirus to people. Several different types of wild mice and rats can be infected with hantavirus and pass it in their droppings, urine, or saliva. The common house mouse does not carry hantavirus. People can get hantavirus when they touch rodent urine, droppings, or places where these animals have nested. Dried droppings or urine can be stirred up in dust and breathed in by people. Hantavirus has not been shown to infect other kinds of animals, such as dogs, cats, or farm animals.
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