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emerging diseases


									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

    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
    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.

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.


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, 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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