Annual Bloodborne Pathogen/infectious Disease Information

Tuberculosis: (abbreviated as TB for tubercle bacillus or Tuberculosis) Is a common and deadly infectious disease caused by mycobacteria, mainly Mycobacterium tuberculosis. Tuberculosis most commonly attacks the lungs (as a pulmonary TB) but can also affect the central nervous system, the lymphatic system, the circulatory system, the genitourinary system, bones, joints and even the skin. Other mycobacteria such as Mycobacterium bovis, Mycobacterium africanum, Mycobacterium cannetti, and Mycobacterium microti can also cause tuberculosis, but these species do not usually infect healthy adults.
One third of the world’s current population has been infected by TB, and new infections occur at a rate of one per second. Not everyone infected develops the full-blown disease; asymptomatic, latent infection is the most common. However, one in ten latent infections will progress to active disease, which, if left untreated, kills more than half of its victims. In 2004, mortality and morbidity statistics included 14.6 million chronic active cases, 8.9 million new cases, and 1.6 million deaths, mostly in developing countries. In addition, a rising number of people in the developed world are contracting tuberculosis because their immune systems are compromised by immunosuppressive drugs, substance abuse, or HIV/AIDS.

The rise in HIV infections and the neglect of TB control programs have enabled a resurgence of tuberculosis. The emergence of drug –resistant strains has also contributed to this new epidemic with, from years 2000 to 2004 20% of TB cases being resistant to standard treatments and 2% resistant to second-line drugs. TB incidence varies widely, even in neighboring countries, apparently because of differences in health care systems.

In the past, tuberculosis has been called consumption, because it seemed to consume people from within, with a bloody cough, fever, pallor, and long relentless wasting. Other names included phthisis (Greek for consumption) and phthisis pulmonalis: scrofula (in adults), affecting the lymphatic system and resulting in swollen neck glands; tabes mesenterica, TB of the abdomen and lupus vulgaris, TB of the skin; wasting disease; white plague, because sufferers appear markedly pale; king’s evil, because it was believed that a king’s touch would heal scrofula; and Pott’s disease, or gibbus of the spine and joints. Miliary tuberculosis-now commonly known as disseminated TB occurs when the infection invades the circulatory system resulting in lesions which have the appearance of millet seeds on X-ray.

When the disease becomes active, 75% of the cases are pulmonary TB. Symptoms include chest pain, coughing up blood, and a productive prolonged cough for more than 3 weeks. Systemic symptoms include fever, chills, night sweats, appetite loss, weight loss, pallor, and often a tendency to fatigue easily.

In the other 25% of active cases, the infection moves from the lung, causing other kinds of TB more common in immunosuppressed persons and young children. Extrapulmonary infection sites include the pleura, the central nervous system in meningitis, the lymphatic system in scrofula of the neck, the genitourinary system in urogenital tuberculosis, and bones and joints in Pott’s disease of the spine. An especially serious form is disseminated TB, more commonly known as military tuberculosis. Although extrapulmonary TB is not contagious, it may co-exist with pulmonary TB, which is contagious.
When people suffering from active pulmonary TB cough, sneeze, speak, or spit, they expel infectious aerosol droplets 0.5 to 5 micrometers in diameter. A single sneeze, for instance, can release up to 40,000 droplets. Each one of these droplets may transmit the disease, since the infectious dose of tuberculosis is very low and the inhalation of just a single bacterium can cause a new infection.

Tuberculosis is spread by aerosols created by coughing or sneezing. People with prolonged, frequent, or intenses contact are at particularly high risk of becoming infected, with an estimated 22% infection rate. A person with active but untreated tuberculosis can infect 10 – 15 other people per year. Others at risk include people in areas where TB is common, people who inject drugs using unsanitary needles, residents and employees of high – risk congregate settings racial or ethnic minority populations, children exposed to adults in high – risk categories, patients immunocompromised by conditions such as HIV/AIDS, people who take immunosuppressant drugs, and health care workers serving these high – risk clients.

Transmission can only occur from people with active – not – latent – TB. The probability of transmission from one person to another depends upon the number of infectious droplets expelled by the carrier, the effectiveness of ventilation, the duration of exposure, and the virulence of the M. tuberculosis strain. The chain of transmission can therefore be broken by isolating patients with active disease and starting effective anti – tuberculosis therapy. After two weeks of such treatment, people with non – resistant active TB generally cease to be contagious. If someone does become infectious, then it will take at least from 21 days, or 3 – 4 weeks, before the new infectiouos person can transmit the disease to others. TB can also be transmitted by eating meat if the cattle is infected with TB. Mycobaterium bovis causes TB in cattle.

Pathogenesis
Mycobacterium tuberculosis ( stained red )in sputum. About 90 % of those infected with Mycobacterium tuberculosis have asymptomatic, latent TB infection ( sometimes called LTBI ), with only 10 % lifetime chance that a latent infection will progress to TB disease. However, if untreated, the death rate for these active TB cases is more than 50 %.
TB infection begins when the mycobacteria reach the pulmonary alveoli, where they invade and replicate within the alveolar macrophages. Further spread is through the bloodstream to the more distant tissues and organs where secondary TB lesions can develop in lung apices, peripheral lymph nodes, kidneys, brain, and bone. All parts of the body can be affected by the disease, though it rarely affects the heart, skeletal muscles, pancreas and thyroid.

Tuberculosis is classified as one of the granulomatous inflammatory conditions. Macrophages, T lymphocytes, B lymphocytes and fibroblasts are among the cells that aggregate to form granuloma, with lymphocytes surrounding the infected macrophages. The granuloma functions not only to prevent dissemination of the mycobacteria, but also provides a local environment for communication of cells of the immune system. Within the granuloma, T lymphocytes ( CD4+ ) secrete cytokinases such as interferon gamma, which activates macrophages to destroy the bacteria with which they are infected. T lymphocytes ( CD8+ ) can also directly kill infected cells.

Importantly, bacteria are not always eliminated within the granuloma, but can become dormant, resulting in a latent infection. Another feature of the granulomas of human tuberculosis is the development of cell death, also called necrosis, in the center of tubercles. To the naked eye this has the texture of soft white cheese and was termed caseous necrosis.
If TB bacteria gain entry to the bloodstream from an area of damaged tissue they spread through the body and set up many foci of infection, all appearing as tiny white tubercles ( In anatomy, a tubercle is a round nodule, small eminence, or warty outgrowth found on bones, skin, or within the lungs in tuberculosis) in the tissues. This severe form of TB disease is most common in infants and the elderly and is called military tuberculosis. Patients with this disseminated TB have a fatality rate of approximately 20 % even with intensive treatment.

In many patients the infection waxes and wanes. Tissue destruction and necrosis are balanced by healing and fibrosis. Affected tissue is replaced by scarring and cavities filled with cheese – like necrotic material. During active disease, some of these cavities are joined to the air passages bronchi and this material can be coughed up. It contains living bacteria and can therefore pass on infection. Treatment with appropriate antibiotics kills bacteria and allows healing to take place. Upon cure, affected areas are eventually replaced by scar tissue.

Diagnosis
Mantoux tuberculin skin test.
Tuberculosis can be a difficult disease to diagnose, mainly due to the difficulty in culturing this slow – growing organism in the laboratory ( 4 – 12 weeks for blood culture ). A complete medica evaluation for TB must include a medical history, a chest x – ray, and a physical examination. Tuberculosis radiology is used in the diagnosis of TB. It may also include a tuberculin skin test, microbiological smears and cultures. The interpretation of the tuberculin skin test depends upon the person’s risk factors for infection and progression to TB disease, such as exposure to other cases of TB or immunosuppression.
Currently, latent infection is diagnosed in a non – immunized person by a tuberculin skin test, which yields a delayed hypersensitivity type response to an extract made from M. tuberculosis. Those immunized forTB or with past – cleared infection will respond with delayed hypersensitivity parallel to those currently in a state of infection, so the test must be used with caution, particularly with regard to persons from countries where TB immunization is common. New TB tests are being developed that offer the hope of cheap, fast and more accurate TB testing. These are polymerase chain reaction detection of bacterial DNA and antibody assays to detect the release of interferon gamma in response to mycobacteria. These tests are not affected by immunization, so generate fewer false positive results. Rapid and inexpensive diagnosis will be particularly valuable in the developing world.
Progression
Progression from TB infection to TB disease occurs when the TB bacilli overcome the immune system defenses and begin to multiply. In primary TB disease 1 – 5 % of cases this occurs soon after infection. However, in the majority of cases, a latent infection occurs that has no obvious symptoms. These dormant bacilli can produce tuberculosis in 2 – 23 % of these latent cases, often many years after infection. The risk of reactivation increases with immunosuppression, such as that caused by the infection with HIV. In patients co – infected with M. tuberculosis and HIV, the risk of reactivation increases to 10 % per year.
Treatment

Ttreatment for TB uses antibiotics to kill the bacteria. The two antibiotics most commonly used are Rifampin and Pyrazinamide. However, instead of the short course of antibiotics typically used to cure other bacterial infections, TB requires much longer periods of treatment ( around 6 – 12 months ) to entirely eliminate mycobacteria from the body. Latent TB treatment usually uses a single dose antibiotic, while active TB disease is best treated with combinations of several antibiotics, to reduce the risk of the bacteria developing antibiotic resistance. People with latent infections are treated to prevent them from progressing to active TB disease later in life. However, treatment using Rifampin and Pyrazinamide is not risk – free. The Center for Disease Control and Prevention ( CDC ) notified healthcare professionals of revised recommendations against the use of Rifampin plus Pyrazinamide for treatment of latent tuberculosis infection, due to high rates of hospitalization and death from liver injury associated with the combined use of these drugs.

Drug resistant tuberculosis is transmitted in the same way as regular TB. Primary resistance occurs in persons who are infected with a resistant strain of TB. A patient with fully – susceptible TB develops secondary resistance ( acquired resistance ) during TB therapy because of inadequate treatment, not taking the prescribed regimen appropriately, or using low quality medication. Drug resistant TB is a public health issue in many developing countries, as treatment is longer and requires more expensive drugs. Multi – drug resistant TB ( MDR – TB ) is defined as resistance to the two most effective first line TB drugs : Rifampin and Pyrazinamide. Extensively drug resistant TB ( XDR – TB ) is also resistant to three or more of the six classes of second line drugs.

History
Tuberculosis has been present in humans since antiquity. The earliest unambiguous detection of Mycobacterium tuberculosis is in the remains of bison dated 18,000 years before the present. However, whether tuberculosis originated in cattle and then transferred to humans, or diverged from a common ancestor, is currently unclear. Skeletal remains show prehistoric humans ( 4000 BC ) had TB and tubercular decay has been found in the spines of mummies from ( 3000 – 2400 BC ).** Phthisis is a Greek term for tuberculosis; around 460 BC, Hippocrates identified Phthisis as the most widespread disease of the times involving coughing up blood and fever, which was almost always fatal. Genetic studied suggest that TB was present in South America for about 2,000 years. In South America, the earliest evidence of tuberculosis is associated with the Paracas – Caverna culture ( circa 750 BC to circa 100 AD ).
** To read the full article, go to : http://en.wikipedia.org/wiki/Tuberculosis

Folklore
Before the Industrial Revolution, tuberculosis may sometimes have been regarded as vampirism. When one member of a family died from it, the other members that were infected would lose their health slowly. People believed that this was caused by the original victim draining the life from the other family members. Furthermore, people who had TB exhibited symptoms similar to what people considered to be vampire traits. People with TB often have symptoms such as red, swollen eyes ( which also creates a sensitivity to bright light ), pale skin and coughing blood, suggest the idea that the only way for the afflicted to replenish this loss of blood was by sucking blood. Another, folklore belief attributed it to being forced, nightly, to attend fairy revels, so that the victim wasted away owing it to the lack of rest; this belief was most common when a strong connection was seen between the fairies and the dead. Similarly, but less commonly, it was attributed to the victims being “hagridden” being transformed into horses by witches (hags) to travel to their nightly meetings, again resulting in a lack of rest.

Hepatitis
Hepatitis implies injury to the liver characterized by the presence of inflammatory cells in the tissue of the organ. The name is from ancient Greek hepar or hepato, meaning liver, and a suffix – it is, meaning inflammation. The condition can be self limiting, healing on its own, or can progress to scarring of the liver. Hepatitis is acute when it lasts less than six months and chronic when it persists longer. A group of viruses known as the hepatitis viruses cause most cases of liver damage worldwide. Hepatitis can also be due to toxins ( notably alcohol ), other infections or from autoimmune process. It may run a subclinical course when the affected person fell ill. The patient becomes unwell and symptomatic when the disease impairs liver functions that include, among other things, removal of harmful substances, regulation of blood composition, and production of bile to help digestion.

Signs and symptoms

Acute Hepatitis
Clinically, the course of acute hepatitis varies widely from mild symptoms requiring no treatment to fulminant hepatic failure needing liver transplantation. Acute viral hepatitis is more likely to be asymptomatic in younger people. Symptomatic individuals may present after convalescent stage of 7 to 10 days, with the total illness lasting 2 to 6 weeks.
Initial features are of nonspecific flu – like symptoms, common to almost all acute viral infections and may include malaise, muscle and joint aches, fever, nausea or vomiting, diarrhea, and headache. More specific symptoms, which can be present in acute hepatitis from any cause, are ; profound loss of appetite, aversion to smoking among smokers, dark urine, yellowing of eyes and skin ( i.e. jaundice ) and abdominal discomfort. Physical findings are usually minimal, apart from jaundice (33 % ) and tender hepatomegaly ( 10 % ). There can be occasional lymphadenopathy ( 5 % ) or splenomegaly ( 5 % ).

Chronic Hepatitis
Majority of patients will remain asymptomatic or mildly symptomatic, abnormal blood tests being the only manifestation. Features may be related to the extent of liver damage or the cause of hepatitis. Many experience return of symptoms related to acute hepatitis. Jaundice can be a late feature and may indicate extensive damage. Other features include abdominal fullness from enlarged liver or spleen, low grade fever and fluid retention ( ascites ). Extensive damage and scarring of liver ( i.e., cirrhosis ) leads to weight loss, easy bruising and bleeding tendencies.

Hepatitis B
Hepatitis B is caused by a hepadnavirus, which can cause both acute and chronic hepatitis. Chronic hepatitis develops in the 15 % of patients who are unable to eliminate the virus after an initial infection. Identified methods of transmission include blood ( blood transfusion , now rare ), tattoos ( both amateur and professionally done ), sexually ( through sexual intercourse or through contact with blood or bodily fluids ), or via mother to child by breast feeding ( minimal evidence of transplacental crossing ). However, in about half of the cases the source of infection cannot be determined. Blood contact can occur by sharing syringes in intravenous drug use, shaving accessories such as razor blades, or touching wounds on infected persons. Needle exchange programs have been created in many countries as a form of prevention.
Patients with chronic hepatitis B have antibodies against hepatitis B, but these antibodies are not enough to clear the infection that establishes itself in the DNA of the affected liver cells. The continued production of virus combined with antibodies is a likely cause of the immune complex disease seen in these patients. A vaccine is available that will prevent infection from hepatitis B for life. Hepatitis B infections result in 500,000 to 1,200,000 deaths per year worldwide due to the complications of chronic hepatitis, cirrhosis, and hepatocellular carcinoma. Hepatitis B is endemic in a number of ( mainly South – East Asian ) countries, making cirrhosis and hepatocellular carcinoma big killers. There are six FDA approved treatment options available for persons with a chronic hepatitis B infection: Alpha – Interferon, Pegylated Interferon Adefovir, Entecavir, Telbivudine, and Lamivudine. About 65 % of persons on treatment achieve a sustained response.
Hepatitis B is the most infectious bloodborne pathogen known.

Hepatitis C
Hepatitis C ( originally “ non – A non – B hepatitis” ) is caused by a virus with an RNA genome that is a member of the Flaviviridae family. It can be transmitted through contact with blood ( including through sexual contact with if the two parties’ blood is mixed ) and can also cross the placenta. Hepatitis C may lead to a chronic from of hepatitis, culminating in cirrhosis. It can remain asymptomatic for 10 – 20 years. Patients with hepatitis C are susceptible to severe hepatitis if they contract either hepatitis A or B, so all hepatitis C patient should be immunized against hepatitis A and B if they are not already immune, and avoid alcohol use. The virus can cause cirrhosis of the liver, HCV viral levels can be reduced to undetectable levels by a combination of Interferon and the anti – viral drug Ribavirin. The genotype of the virus determines the rate of response to this treatment regimen. Genotype 1 is more resistant to Interferon therapy than other HCV genotypes.
**To more information see : http//Wikipedia.org/wiki/Hepatitis

HIV
HIV stands for human immunodefifiency virus. This is the virus that causes AIDS. HIV is different from most other viruses because it attacks the immune system. The immune system gives our bodies the ability to fight infections. HIV finds and destroys a type of white blood cell 9 t cells or CD4 cells ) that the immune system must have to fight disease.

AIDS
Aids stands for acquired immunodeficiency syndrome. AIDS is the final stage of HIV infection. It can take years for a person infected with HIV, even without treatment, to reach this stage. Having AIDS means that the virus has weakened the immune system to the point at which the body has a difficult time fighting infections. When someone has one or more AIDS defining infections and a low number of CD 4+ cells ( < 200 cells per cubic millimeter ), he or she has AIDS.
Origin of HIV
Scientists identified a type of chimpanzee in West Africa as the source of HIV infection in humans. The virus most likely jumped to humans when humans hunted these chimpanzees for meat and came into contact with their infected blood. Over several years, the virus slowly spread across Africa and later into other parts of the world.
Brief history of HIV in the United States
HIV was first identified in the United States in 1981 after a number of gay men started getting sick with a rare type of cancer. It took several years for scientists to develop a test for the virus, to understand how HIV was transmitted between humans, and to determine what people could do to protect themselves. During the early 1980’s, as many as 150,000 people became infected with HIV each year. By the early 1990’s, this rate had dropped to about 40,000 each year, where it remains today.
AIDS cases began to fall dramatically in 1996, when new drugs became available. Today, more people than ever before are living with HIV/AIDS. CDC estimates that about one quarter of those people do not know that they are infected: not knowing puts them and others at risk.
How HIV is transmitted
HIV is a fragile virus. It cannot live for very long outside of the body. As a result, the virus is not transmitted through day – to – day activities such as shaking hands, hugging, or a casual kiss. You cannot become infected from a toilet seat, drinking fountain, doorknob, dishes, drinking glasses, food, or pets. You also cannot get HIV from mosquitoes.
HIV is primarily found in the blood, semen, or vaginal fluid of an infected person. HIV is transmitted in 3 main ways:
1. Having sex ( anal, vaginal, or oral ) with someone infected with HIV
2. Sharing needles and syringes with someone infected with HIV
3. Being exposed ( fetus or infant ) to HIV before or during birth or through breast feeding
HIV also can be transmitted through blood infected with HIV. However, since 1985, all donated blood in the United States has been tested for HIV. Therefore, the risk for HIV through the transfusion of blood or blood products is extremely low. The U.S. blood supply is considered among the safest in the world. There has not been a documented case of HIV transmission in the healthcare setting ( due to percutaneous or mucocutaneous exposure ) in the U.S. since 2001.
Risk factors for HIV transmission
You may be at risk for infection if you have
1. Injected drugs or steroids, during which equipment ( such as needles, syringes, cotton, water ) and blood were shared with others
2. Had unprotected sex vaginal, anal, or oral ( that is, sex without using condoms ) with men who have sex with men, multiple partners, or anonymous partners
3. Exchanged sex for drugs or money
4. Been given a diagnosis of, or been treated for hepatitis, tuberculosis ( TB ), or a sexually transmitted disease ( STD ) such as syphilis
5. Received a blood transfusion or clotting factor during 1978 – 1985
6. Had unprotected sex with someone who has any of the risk factors listed above

To protect yourself, remember these ABC’s
A=Abstinence
B=Be Faithful
C=Condoms

Symptoms of HIV Infection
The only way to know whether you are infected is to be tested for HIV. You cannot rely on symptoms alone because many people who are infected with HIV do not have symptoms for many years. Someone can look and feel healthy but still can be infected. In fact, one quarter of the HIV infected persons in the United States do not know that they are infected.
The following may be warning signs of advanced HIV infection:
1. Rapid weight loss
2. Dry cough
3. Recurring fever or profuse night sweats
4. Profound and unexplained fatigue
5. Swollen lymph glands in the armpits, groin, or neck
6. Diarrhea that lasts for more than a week
7. White spots or unusual blemishes on the tongue, in the mouth, or in the throat
8. Pneumonia
9. Red, brown, pink, or purplish blotches on or under the skin or inside the mouth, nose, or eyelids
10. Memory loss, depression, and other neurological disorders

HIV testing
Once HIV enters the body, the body starts to produce antibodies, substances the immune system creates after infection. Most HIV tests look for these antibodies rather than the virus itself. There are many different kinds of tests, including rapid tests and home test kits. All HIV tests approved by the U.S. Government are very good at finding HIV.

** For more information see www.cdc.gov/hiv/topics/basic/index.htm

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