Wash those hands! Tie that mask! Change those gloves! Don that gown! Don’t recap that needle! From day one of clinical practice, nurses have heard these words from nursing instructors, then from preceptors and infection control specialists. The caveat “First do no harm” carries with it the responsibility to understand the wily ways of microorganisms and thus prevent transmission of infectious diseases and care for those who are afflicted with them.

In particular, nurses need to stay up-to-date on the guidelines for caring for patients with major diseases that threaten the public health, such as TB, hepatitis, and HIV/AIDS as they choose barrier devices and provide treatment.

A Chain of Events

The chain of events surrounding infection involves a source, portal of exit, mode of transmission, portal of entry, and a susceptible host. It begins with the pathogen or infectious agent. Bacteria, such as Mycobacterium tuberculosis, and viruses, including hepatitis and HIV, are potential culprits. The reservoir, or source of the infectious agent, is any person, animal, plant, or substance in which an infectious agent normally lives and multiplies. Next in the chain of events come the portals of exit — sneezing, draining lesions, and blood and body fluids are all means by which pathogens escape.

Mode of transmission is how microorganisms get from place to place or from the source to the host. Modes or routes include contact, droplet, airborne, common vehicle, and vectorborne. Contact transmission, the most common and important mode, includes direct and indirect contact. Direct contact involves direct body-surface-to-body-surface contact between a susceptible host and an infected or colonized person, such as giving a bath or other direct personal hygiene. Indirect contact involves contact of a susceptible host with a contaminated object, such as contaminated instruments, equipment, soiled dressings, or objects that weren't washed.

Droplet transmission is a form of contact; however, the contact occurs when large particle droplets (larger than 5 µm) containing microorganisms are projected when an infected person coughs, sneezes, or talks. Droplets are deposited on conjunctivae, nasal mucosa, or the mouth of the host. Droplets are typically only projected about three feet before falling to the ground. Airborne transmission occurs when droplet nuclei (small-particle residue [5 µm or smaller] of evaporated droplets containing microorganisms that remain suspended in the air) or dust particles containing infectious agents are transmitted through the air. Microorganisms transmitted in this manner can be spread widely through the air and become inhaled or deposited on a host located in the same room, or depending on environmental conditions, over a longer distance.

A common vehicle is the term used to describe contaminated material – inanimate items, such as food, water, medications, medical devices, or equipment – that can transport an infectious agent. Vectorborne transmission occurs when animals and insects transmit microorganisms.

To infect another person, however, there must be a portal of entry — the gastrointestinal tract, skin, placenta, genitourinary system, respiratory tract, mucous membranes, a percutaneous injury, invasive procedures, or vascular access, to name a few. And last, the chain is complete when there is a susceptible host, a person lacking resistance to the offending agent.

Preventing Transmission

Handwashing and isolation precaution strategies are mainstays in preventing cross-infection and protecting both patients and healthcare workers.

Hand Hygiene: Handwashing is the single most important precaution for preventing the spread of infection. Vigorous rubbing of all surfaces of the hands against each other with water and a detergent-type cleanser having detergent activity for a period of 15 seconds, followed by thorough rinsing, will remove cells and adherent bacteria. The detergent activity alone is sufficient to kill many (but not all) bacteria. In October 2002, the Centers for Disease Control and Prevention (CDC) issued new hand-hygiene guidelines that permit the use of alcohol-based hand rubs: “When hands are visibly dirty or contaminated with proteinaceous material or are visibly soiled with blood or other body fluids, wash hands with either a nonantimicrobial soap and water or an antimicrobial soap and water. If hands are not visibly soiled, use an alcohol-based hand rub for routinely decontaminating hands in other [routine] clinical situations.”¹

For more thorough antisepsis, healthcare workers should use an antibacterial cleanser, such as povidone-iodine or chlorhexidine, and a longer duration of scrubbing (five minutes or more). More details about handwashing are listed in Sidebar 1.

Isolation precautions: Isolation precautions are procedures used to prevent transmission of microorganisms from patient to caregiver, caregiver to patient, and patient to patient. Current guidelines provide for two tiers of precautions. The first is called standard precautions and is the primary strategy to prevent nosocomial infections. The second tier, transmission-based precautions, aims to interrupt transmission of specific pathogens that require methods beyond standard precautions.

Standard precautions: Standard precautions, previously called universal precautions, apply routinely to all patients. The same measures of barrier protection to prevent contamination of skin and mucous membranes apply equally to all. Barriers appropriate to the activity, such as gloves, protective eye wear, and impermeable gowns, are used to prevent any and all contact between skin and mucous membranes and blood, body fluids, secretions, and excretions with the exception of sweat.

Transmission-based precautions: Three types of transmission-based precautions are designed for patients documented or suspected to be infected or colonized with highly transmissible or epidemiologically important pathogens that require protection beyond standard precautions.

Airborne precautions are necessary when highly contagious pathogens may be present and can be spread by airborne droplet nuclei that remain suspended in air currents and can be widely dispersed over considerable distances. Examples of these pathogens include varicella, rubeola, and Mycobacterium tuberculosis.²

Droplet precautions are needed when pathogens are transmitted by droplets generated by coughing, sneezing, and talking. These droplets settle out of the air quickly and propagate no more than two or three feet from the source patient. Some pathogens include Neisseria meningitides and Bordetella pertussis.²

Contact precautions are necessary in caring for patients known or thought to be infected or colonized with epidemiologically important microorganisms that can be transmitted by direct or indirect contact. Examples include herpes simplex, scabies, and Clostridium dificile.³

The CDC has published the most widely used isolation/precaution guidelines for hospitals in the US. Information can be found online at www.cdc.gov/ncidod/hip/isolat/isopart2.htm.

Needles and Sharps: Many situations place healthcare workers at greater risk of exposure to potentially infectious materials, for example, percutaneous injury. This type of exposure is most likely to occur during the use of sharps, especially when work practices fail to address obvious risk, such as any use of exposed needles, recapping used needles, manipulation of used needles or other sharps by hand, removal of scalpel blades, blind suturing, use of fingers and hands in the vicinity of or to oppose a suture needle, passing of needles or sharps from one to another, failing to account for sharps used in a procedure, and disposal of used sharps.

The best options are to avoid the use of unprotected needles and use safety protected needles when possible. Use a needleless delivery system for IV administration of medication, fluids, and nutrition. With such a system, withdrawal of blood specimens, piggybacks, and administration of medications can be achieved using blunt end connectors instead of sharp needles. Many manufacturers now offer a variety of safety devices that reduce the risk of sharps injuries. These safety devices include safety IV catheters, self-blunting phlebotomy needles, safety butterfly needles, and safety syringes. Activation of the safety mechanism, whether active or passive, will reduce the risk of a sharps injury.

Protecting the Health of Communities

Understanding disease processes, modes of transmission, and all the other elements in the chain of events that can lead to infection are especially critical in diseases, such as TB, hepatitis, and HIV/AIDS, that threaten individual lives and the health of entire communities and populations. Historically, nurses have been key players in protecting the public’s health. The following sections on common pathogens and diseases present information on preventing and managing common infectious diseases that can wreak havoc if left unchecked.

TB: A Continuing Challenge

In the late 1970s and early 1980s, healthcare professionals thought that TB had just about been eradicated. Because of declining cases and, more importantly, the public health system’s ability to treat patients without prolonged period of confinement, most TB programs and sanitariums were closed. With the rapid growth of AIDS and worsening socioeconomic conditions in the mid-1980s, however, health officials warned that TB had returned to pose a serious threat to the public's health.

Today, healthcare professionals have learned about the prevention, diagnosis, and treatment of TB and MDRTB, which is TB that is resistant to at least both isoniazid (INH) and rifampin (RIF). They are educating the public about prevention and new approaches to treatment, particularly for MDRTB.

Background and Trends: In 1992, reported TB cases in the US were 26,673 (10.5 per 100,000).⁴ By 2000, the number dropped to 16,373 cases (5.8 per 100,000), representing a 39% decrease from the peak resurgence of 1992.⁵ The number further declined to 14,874 (5.1 per 100,000) in 2003.  In 2003 in Puerto Rico, cases had declined to 115 (3 per 100,000) from 200 (5.1 per 100,000) in 1999.⁶

The resurgence of TB and MDRTB seen from 1985 to 1992 was attributable primarily to the AIDS epidemic, “the most potent facilitator of TB ever known.”⁷ Other contributing factors included increases in substance abuse, homelessness, immigration, and lack of patient adherence to drug therapy. The nature of the disease changed dramatically as more cases of MDRTB were identified in the early 1990s.

A number of TB facts shed light on the extent of the world's TB problem.⁸

• TB presents a larger problem in the world, particularly in developing countries where it accounts for more than one quarter of all preventable deaths.
• Two billion people are infected with the TB bacteria, one third of the world's population.
• Every day, 20,000 people develop TB disease and 5,000 people die from it.
• TB is the single most opportunistic infection for people living with HIV/AIDS, accounting for one third of AIDS deaths worldwide.
• TB causes more deaths among women than all causes of maternal mortality combined.
• On average, one person dies of TB every 15 seconds.

TB control programs have two major aims – to detect people with active TB and treat them with effective anti-TB drugs, and to detect and preventively treat those who have latent TB infection and may be at high risk of developing active TB.

Active surveillance and case finding is a fundamental activity of TB control programs. It is important that all people suspected or diagnosed with TB are reported to the local health department or TB control program in accordance with communicable disease reporting regulations (usually reporting is required within 24 to 48 hours). This includes all people started on anti-TB medications in hospitals, private physicians' offices, or community health centers. In Puerto Rico, healthcare workers are required to notify the Program of Tuberculosis, Department of Health, about patients who have signs and symptoms of TB.

People at high risk for TB infection include –

• Close contacts of known or suspected infectious TB cases
• Foreign-born persons from areas where TB is common
• Residents or employees of high-risk congregate settings, such as nursing homes, correctional settings, and homeless shelters
• Healthcare workers who serve high-risk patients
• Medically underserved, low-income populations
• High-risk racial or ethnic minority populations, defined locally as having an increased prevalence of TB, and infants, children, and adolescents exposed to adults in high-risk categories
• People who inject illicit drugs, or any other locally identified high-risk substance users, such as crack-cocaine users.⁹

MDRTB is a much more serious disease than TB, and it requires complex drug therapy. Cases of MDRTB are difficult to track and follow-up may be incomplete, resulting in poor compliance and failure to complete the drug protocol. The problem of MDRTB is higher where persons reside in an endemic area and are exposed to drug-resistant cases.

The Disease Process: TB is an infectious disease caused by M. tuberculosis that affects the pulmonary system and, if left untreated, may spread to the bones and other organs. TB is acquired by inhalation of droplet nuclei-containing bacteria aerosolized from persons who are infectious and untreated or who failed to complete prior treatment. The duration of contact or exposure to the infectious person is an important determinant, and the length of time from exposure to the development of TB depends on the individual's immune system.

Inhaled organisms accumulate in the alveoli of the well-ventilated, lower lobes of the lungs. They replicate and gain access to lymphatic channels through the cervical nodes and thoracic duct to disseminate throughout the bloodstream. The infected individual may develop bronchopneumonia, usually in the upper lobes with regional lymph involvement. Unilateral pleural effusion, which may be present during the initial infection, is referred to as primary TB. More often, the person remains asymptomatic and a tuberculin skin test may indicate a positive reaction two to 10 weeks after the initial infection occurs.

Most people with positive skin tests harbor viable organisms within macrophages, maintaining a balanced host-parasite relationship (dormant or latent TB) for years. Most TB cases are a reactivation of organisms from the dormant stage, referred to as reactivation TB, which usually occurs when the immune defenses are compromised.

Risk Factors: Certain people, including the elderly, IV drug abusers, and the chronically ill or immunocompromised who are debilitated by cancer or HIV, may have certain conditions that increase the risk of progression from latent TB infection to disease, including –

• HIV infection or AIDS
• Substance abuse, especially IV drug use
• Recent infection with M. tuberculosis within the last two years, particularly infants and very young children
• Chest x-ray indicative of previous TB in a person who received inadequate or no treatment
• Certain medical conditions, such as diabetes, silicosis, end-stage renal disease, prolonged corticosteroid therapy, cancer of the head and neck, hematological and reticuloendothelial diseases, intestinal bypass or gastrectomy, and chronic malabsorption syndrome
• Low body weight (10% or less than ideal)
• Immunosuppressive therapy.⁹

Recognizing and Diagnosing TB: Symptoms of TB vary depending on where the TB bacteria are growing in the body, usually the lungs. Pulmonary TB usually causes a persistent cough that lasts longer than two weeks, chest pain, and coughing up blood or sputum from deep inside the lungs.⁴ The signs and symptoms of TB may vary markedly, especially in immunosuppressed groups where the manifestations may be subtle. Indicators include weight loss, cough (productive or nonproductive), anorexia, weakness, fatigue, dyspnea, and low-grade fever. Night sweats, hemoptysis, and cervical lymphadenopathy may occur. An assessment of risk factors for latent TB infection and progression from TB infection to disease is also important in determining the person's risk of TB disease.

The key to timely diagnosis is the early testing of anyone with typical signs and symptoms, a history of recent exposure, or membership in a high-risk group. Diagnosis comprises a Mantoux skin test, chest x-ray, and sputum for culture and sensitivity.

The tuberculin (Mantoux) skin test is 0.1 ml of purified protein derivative (PPD) injected intradermally into the surface of the forearm. The tuberculin syringe must be held close to the skin so that the needle hub (26 or 27 gauge) touches it as the needle is introduced, bevel up. This reduces the needle angle at the skin surface and promotes the injection just beneath the skin to form a wheal.

Examine the skin test site within 48 to 72 hours in adequate light. A positive reaction may be read at up to one week post testing, but a negative must be read within 72 hours. However, some people may actually not react sufficiently until more than 72 hours. Use a pen to mark the area of induration (hardness) that is palpated – not the area of redness. Redness is not a reliable indicator of reactivity. Measure the area of induration with a flexible millimeter ruler. Record the reading in millimeters, not as positive or negative. The size of induration correlates with the probability of TB. An area of 5 mm or greater is considered a positive result in a person with HIV, or in those with close contact to an active case, those with abnormal chest X-ray results caused by TB, and those who are otherwise immunocompromised. Induration of 10 mm or greater in a high-risk group is also considered positive. Induration of 15 mm or greater is considered a positive result in those without known risk. When the area of induration increases to more than 10 mm within a two-year period, the person is considered a tuberculin converter.

In those over age 65 and persons with immunocompromised states who have a negative test, and who have not been previously tested within the past year, repeat the Mantoux in one week to three weeks to boost the chances of detecting reactivity and be able to differentiate between recent conversion and past infection. Do not retest a patient with a history of a positive skin test. A positive PPD only indicates that the person is presently or has previously been infected and does not distinguish between active and dormant disease.

Immunization with the BCG vaccine (Bacillus Calmette Guerin), an attenuated form of the bacillus, is not a contraindication for PPD skin testing. Many people who have been immunized with BCG do not have a positive PPD. People with a history of prior BCG immunization who have positive reactions to a Mantoux PPD are considered to have TB.¹¹

A chest x-ray is an important diagnostic tool in evaluating patients with pulmonary TB. Abnormal findings may include infiltrates and/or cavitation, usually in one or both upper lobes, although these may be found anywhere in the lungs. People with HIV may present with atypical findings. However, only identification through a bacteriological culture can confirm that an individual has TB. The chest x-ray is used to rule out TB in a person with a positive tuberculin skin test and no symptoms of TB. In some cases, a computed tomography scan may be necessary.¹⁰

Sputum for acid-fast bacilli (AFB) should be collected if the person has signs and symptoms of TB, particularly a cough, abnormal chest x-ray, and/or a history of inadequately treated TB or treatment failure. It is collected initially to aid in diagnosis, then later to determine the effectiveness of therapy. Sputum is collected monthly throughout the course of TB treatment from patients who are diagnosed with pulmonary TB. Three early morning samples should be collected to reduce the chances of missing a positive result. A positive AFB result on a concentrated sputum smear indicates that a patient is infectious, if M. tuberculosis is identified. The concentrated AFB findings can be obtained in 24 to 48 hours. The culture identification takes longer, usually two to four weeks. Not all organisms that are AFB turn out to be M. tuberculosis. There are a number of AFB organisms, but only M. tuberculosis causes TB. The differentiation is made based on the final culture and other specific tests. Drug sensitivities take approximately one to two weeks following culture identification and growth.

Treatment: Current treatment programs, if properly followed and completed by the patient, can cure TB disease and prevent the development of TB disease in later life. A major challenge is to design the shortest possible regimen to minimize adverse drug effects and enhance patient adherence. Most protocols for prevention and treatment include the following measures.

Treatment of Latent TB Infection: Patients suspected of having latent TB should have a chest X-ray before treatment is considered.⁹ Even those without evidence of clinical disease need to be evaluated for treatment.

Isoniazid (INH) is the most effective known treatment for latent TB infection, according to the results of clinical trials throughout the world. It is prescribed based on mg/kg. The patient should take INH daily for nine months, or 270 doses within a 12-month period. It may also be taken for six months daily or 180 doses within a nine-month period, as long as the patient is HIV-negative and has a normal chest x-ray. It may be taken twice weekly, only if directly observed therapy (DOT) is provided, for at least 76 doses within 12 months. Another acceptable regimen includes rifampin (RIF) with a dose of milligrams per kilogram (mg/kg), up to 600 mg daily for four months for people who are HIV negative and have contact with people with INH-resistant RIF-susceptible TB.¹²

The patients who have the highest relative risk for developing TB disease once infected, as described earlier, should be treated for latent TB infection regardless of age.

CDC guidelines recommend that contacts who initially exhibit a negative PPD reaction need to receive a second tuberculin test 10 to 12 weeks after the initial injection. If the repeat skin test remains negative and contact with the source case has been broken, no further testing is necessary; if the person had been started on prophylaxis, treatment may be stopped. If the repeated PPD is positive, a chest x-ray is done to exclude disease; if there is no evidence of disease, a full course of treatment is given. Contacts who have HIV infections are given treatment, regardless of tuberculin skin test results. A history of liver disease may preclude the use of INH, which is metabolized by the liver.

Treatment of Active TB: All positive cultures for AFB must undergo examination to rule out atypical Mycobacterium infections. Drug sensitivity studies are also necessary because of rising incidence of drug resistance, especially with nonadherent patients or those who did not complete prior treatment.

The initial regimen for treatment of active TB usually includes four drugs – INH, RIF, pyrazinamide (PZA), and ethambutol (EMB) or streptomycin (SM). All TB drugs are prescribed based on the patient's weight, mg/kg.

These four drugs should be taken until the sputum culture converts from positive to negative and drug sensitivities are reviewed by the provider, which may take up to eight weeks or more. Sputum conversion may take longer for patients who have advanced disease, in cases where there is malabsorption or ineffective metabolism of the TB drugs, or when the patient is resistant to one or more of the four first-line drugs. Once sputum cultures convert to negative, the drug therapy may be modified for the remainder of the treatment course.

A preferred six-month protocol for the treatment of active TB includes an initial course of daily INH, usually 300 mg; RIF 600 mg daily; and PZA and EMB by weight daily for two months. EMB is started when therapy is initiated, and may be discontinued as soon as sensitivities warrant. SM may be used in place of EMB when necessary, but is not the drug of choice because of the possibility of eighth cranial nerve damage, kidney stones, and its use for the IM route only. A continuation phase of INH and RIF follows for four months.¹³

Sensitivity tests from sputum analysis guides the modification of treatment protocols for patients with drug-resistant strains. Resistance is common in patients who have been on inadequate treatment previously, in those who have recently acquired TB (more likely to have a resistant strain), and in immigrants from areas with a high prevalence of resistant strains.

Nurses must monitor patients for compliance and adverse effects of drug therapy. A baseline assessment includes liver enzymes, bilirubin, serum creatinine, and complete blood count with platelet count. Serum uric acid is measured when PZA is prescribed. Monitor patients, especially the elderly taking INH, at least every one to two months for signs and symptoms of hepatotoxicity, such as fatigue, jaundice, fever, anorexia, and dark-colored urine. Assure those who take RIF that this drug normally changes the color of urine, saliva, sputum, sweat, and tears to an orange-red. Monthly monitoring for adverse reactions to all TB medications is recommended. For example, a baseline and monthly visual acuity and color discrimination is required for patients taking EMB because the drug may cause optic neuritis.

Since most TB medications are metabolized in the liver, the risk for medication-induced hepatitis is increased, particularly if the patient uses illicit drugs, is an alcoholic, or has an underlying liver disorder. Discuss with the patient all other medications, including over-the-counter drugs, such as aspirin or acetaminophen.

In general, the following guidelines should be discussed with the patient and family involved with RIF –

• RIF can turn urine, saliva, sweat, or tears orange; advise patients not to wear soft contact lenses because they may become stained.
• RIF causes hypersensitivity to the sun: use a good sunscreen when sun exposure occurs.
• RIF makes birth control pills and implants less effective; another method may need to be used.
• RIF taken along with methadone may cause withdrawal symptoms and require an increased dosage of methadone.¹³

Preventing Transmission: Airborne precautions are necessary to prevent transmission of TB. A disposable particulate respirator (PR) mask should be worn by anyone entering the room of a patient known or suspected of infectious pulmonary tuberculosis. The PR mask must fit snugly and have a specialized filter designed to filter small-particle residue of the droplet nuclei which are typically 5 microns in diameter or less. The patient should be placed in a private room that has negative air pressure and the door of the room should remain closed.

Healthcare facilities with suspected or identified TB patients need to provide adequate respiratory protection, including PR masks, to employees and visitors. Facilities must have a routine skin-testing program for all employees, as well as an annual educational offering on infection control. Prophylactic treatment and follow-up therapy need to be available for employees who are exposed to the bacterium and convert to a positive PPD.

Hepatitis A & B – Public Health Concerns

Hepatitis – inflammation of the liver – can have viral, bacterial, physical, or chemical etiologies. Symptoms may include fever, hepatomegaly, fatigue, and jaundice.¹⁴ Although hepatitis A and B are both preventable with a vaccine, they remain major public health concerns. In 2002, the most recently compiled national statistics by the CDC indicate that cases of hepatitis A and B are declining.

Hepatitis A (HAV): Hepatitis A is the most common type of hepatitis in the US. For 2002, the CDC reported the lowest 8,795 cases, representing an incidence rate of 3.1 per 100,000, the lowest ever recorded. The decreased incidence is thought be a direct result of increased immunization.  In Puerto Rico, there were 239 cases during the same year.¹⁵ A vaccine has been available since 1995.

The Disease Process: Originally known as infectious serum hepatitis, scientists identified the hepatitis A virus in 1979. It can live in the environment for months, and be inactivated by formalin, chlorine, or temperatures higher than 185° F. Humans are its only natural host.¹⁷

The incubation period is 15 days to 50 days (average 28). Symptoms are usually abrupt, including fatigue, the most common symptom; fever; brown urine (bilirubinuria); light-colored stools; abdominal pain; anorexia; nausea and vomiting; diarrhea; jaundice; and pruritis. Jaundice and dark urine usually occur four days to 10 days after the preicteric phase; the liver enzymes, aspartate aminotransferase (AST) and alanine aminotransferase (ALT), are markedly elevated. Serum bilirubin is increased. Illness usually lasts no more than two months, although symptoms may last for as long as six months. Most people fully recover, with no long-term liver damage. There is no chronic carrier state in hepatitis A infection.¹⁸

The infection can also be asymptomatic. In fact, 70% of children younger than six years old exhibit no symptoms, but still test positive and are infectious. On the other hand, approximately the same percentage of infected individuals age six or older are symptomatic, and approximately 0.3% die each year from fulminant acute hepatitis A. Those over age 50 have a 1.8 % fatality rate.¹⁷

Recognition and Diagnosis: Hepatitis A is primarily transmitted via the fecal-oral route, although rare cases of transmission have occurred through the transfusion of blood products obtained from infected donors during the incubation period. The virus is found in feces, usually in highest concentrations about two weeks before onset of symptoms, diminishing rapidly with liver dysfunction and symptoms. A person is generally considered infectious from two weeks before to one week after onset of jaundice. If jaundice doesn’t appear, it is difficult to determine this timeframe.¹⁹

Detection of serum HAV IgM indicates acute infection and may be apparent several days before symptoms emerge until three to 12 months after onset. IgG also becomes detectable with the onset of symptoms, and high titers should remain  for life, conferring immunity. Separate IgM testing is required for a definitive diagnosis.¹⁹

Preventing Transmission: The most important approach to preventing fecal-oral transmission is good handwashing after a bowel movement and before preparing food. Another means is to avoid ingesting untreated water. It is also important to follow good technique when handling and preparing food, such as shellfish, because some outbreaks of HAV have been related to improper cooking and handling of contaminated shellfish. A vaccine has been available since 1995 for people ages two and older. It is an inactivated virus vaccine, given in a two-dose series, six months to 12 months apart. The first dose confers greater than 90% immunity, while the second dose boosts this to nearly 100%. In the US, routine childhood vaccination is recommended for those living in designated states that  had a higher incidence of the disease, which also includes Puerto Rico.²⁰

Those who are unvaccinated and have been exposed to someone with an acute case of hepatitis A can avoid illness or reduce the severity of symptoms (by more than 85%) by receiving gamma globulin within 14 days of the last exposure. People may acquire up to five months’ passive immunity.²⁰

Treatment: Palliative care is all that is available to a patient with acute hepatitis A. This includes rest, hydration, frequent small feedings with low-fat and high-carbohydrate foods, abstinence from alcohol, and avoidance of medications, especially sedatives and chlorpromazine.

Hepatitis B (HBV): In 2002, 7,996 acute cases of HBV were reported to the CDC in the

US. This represents a more than 65% reduction since 1990, although it doesn’t include asymptomatic (mostly infants and children) and chronic carriers.¹⁵ For the same year, 211 cases were reported in Puerto Rico.¹⁵ HBV is the fourth leading cause of cancer death in the world and 80% of liver cancer worldwide is caused by chronic HVB infection.²¹

HBV, a double-shelled DNA virus in the Hepadnaviridae class, was differentiated from hepatitis A in the 1940s by transmission modes. It was probably first recognized in 1883 when German shipyard workers became jaundiced after receiving a smallpox vaccination that contained human lymph. Jaundice was regularly observed in the early 1900s after reuse of needles and syringes; transmission from a blood transfusion was documented in 1943. The surface antigen (HBsAg) was first identified in 1965, and the complete virus in 1970.¹⁷

The Disease Process: The incubation period for HBV is 45 days to 180 days, with an average of 90 days. Symptoms are indistinguishable from other forms of hepatitis. Less than 10% of children and 30% to 50% of acutely infected adults develop jaundice. About 2% develop fulminant hepatitis, of which as many as 93% die. Unlike hepatitis A, about 5% to 10% of people with acute infections do not clear the virus and become chronic carriers. Generally, patients still HBsAg positive six months after onset are considered chronic carriers – a risk that decreases with age. Up to 90% of infants born with HBV will become carriers. Children infected between ages one and five have a 30 to 50% chance of chronicity, while the risk during adulthood is 6 to 10%.¹⁸

Chronic carriers are usually not aware of their infection unless they have been tested, because they are generally asymptomatic. They may still be infectious and have about a 25% chance of developing chronic active hepatitis, which often results in cirrhosis and 3,000 to 4,000 deaths in the US annually. They also have up to 300 times the risk for hepatocellular carcinoma than the general population. Each year, 1,000 to 1,500 will die in the US from liver cancer associated with HBV.¹⁷

Recognition and Diagnosis: All blood products, tissue, and human organs are screened for HBV before use, and testing is widely available to the general population. Prenatal screening should include testing for HBsAg. A full panel of laboratory tests should be performed because several viral particles can be detected in serum, which carry their own significance, either individually or in combination. Testing can uncover current acute, past, or chronic infection, and immunity.

Preventing Transmission: Blood and other body fluids that are HBsAg positive should be considered infectious. The highest concentrations of virus are found in blood and serous fluids. Saliva, semen, and vaginal secretions may also be infectious, but these are not common transmission modes. Saliva transmission has been documented through human bites. Kissing or being spit on are considered extremely low risk. No infections have been attributed to tears, sweat, feces, urine, or droplets. The virus can remain infectious on inanimate surfaces for at least 30 days. It is inactivated by normal sterilization methods.²¹

Sexual contact is the most common mode of viral transmission. Other modes of transmission include injectable drug use, household contact with an infected person, perinatal contact with an infected mother, and healthcare worker contact with an infected patient. The remainder of cases fall into the unknown risk category (commonly because patients refused to be interviewed).¹⁵

Perinatal transmission occurs in 70% to 90% of infants whose mothers were both HBsAg and HBeAg positive, although that number drops to about 20% if mothers are only surface antigen positive.¹⁸ HBeAg is thought to be related to infectivity, thus, if present in blood, more likely to be infectious.

The spread of HBV can be prevented through abstinence or the use of latex condoms during sexual intercourse; never sharing injection drug equipment or bleaching after each use; not sharing personal items, such as a toothbrush or razor; avoiding acupuncture or tattooing except from a licensed practitioner; thorough prenatal screening; observing standard precautions; and responding promptly to an on-the-job exposure. Hepatitis B vaccine also prevents HBV infection.

Vaccination (inactivated virus), available since 1981, should be strongly considered for healthcare workers who come in contact with potentially infectious material; sexually active individuals, especially those with multiple partners; men who have sex with men; people diagnosed with a sexually transmitted disease, and those who have sex with prostitutes; injection drug users; long-term prisoners; patients who undergo hemodialysis; and household contacts of someone with an acute or chronic case. In spring 2002, a combination hepatitis A and B vaccine was approved for use in adults 18 years and older. The vaccine is now required for school entry in many states in the US and should be given without exception to newborns whose mother is HBsAg positive. Vaccine schedules may vary to some extent, but should always include at least three doses. The second dose should be given no less than one month after the first, and the third dose four months to six months after the second. If there is a gap between doses, the schedule may be resumed without restarting the entire series. Newborns of infected mothers should receive the first dose within 12 hours of birth, as well as one dose of HBIG (hepatitis B immune globulin), 0.5mL IM. The infant should receive the HBIG as soon as possible (no later than 1 week of age). HBIG will not interfere with the infant’s two-month immunizations, and can be given concurrently.²² Only one dose of HBIG is given.

For percutaneous or perimucosal postexposure prophylaxis when the source case is known to be HBsAg positive, an unvaccinated person should receive HBIG immediately and start the vaccine series. A vaccinated person who has a known vaccine response requires no treatment; a known nonresponder should receive HBIG twice or HBIG and restart the vaccine. If the exposure is to a person whose HBsAg status is unknown and that person is considered high-risk for infection, he or she should be considered infected.¹⁷

Treatment: Not everyone with chronic HBV infection requires treatment. However, those who show signs of active liver disease may benefit from treatment. The goal of treatment is to eliminate or significantly suppress HBV replication and prevent the progression of liver disease to cirrhosis with the potential development of liver failure. There have been significant strides made toward reaching this goal over the past 10 years. Currently, there are three drugs approved for first-line therapy in patients with HBeAg-positive chronic HBV infection, including interferon alfa-2b (Intron A), lamivudine (Epivir), and adefovir dipivoxil (Hepsera). ²³

Interferon alfa-2b is administered by subcutaneous injection and therapy is associated with many adverse reactions including fatigue, anorexia, depression, and leukopenia. Interferon alfa-2b is typically administered weekly for 16 weeks.

Lamivudine is typically administered orally, once daily. Adverse reactions include nausea, vomiting, fatigue, depression, neutropenia, hyperglycemia, and diarrhea. Complete blood count should be monitored frequently to watch for signs of bone marrow toxicity. Adefovir is also administered orally, once daily. Adverse reactions include renal dysfunction, weakness, nausea, vomiting, and diarrhea. Liver and kidney function should be monitored throughout treatment.

Several new antiviral agents and immunomodulatory therapies are currently under investigation but have not yet been approved.²³

Hepatitis C: The Shadow Epidemic

There are more than 4 million people who are or have been infected with hepatitis C in the US; 2.7 million of whom are chronically infected. Most of those infected with hepatitis C are 40 to 59 years old. Approximately 70% of those who are infected do not know that they have the virus. Alchoholic liver disease and chronic hepatitis C are the leading causes of cirrhosis and hepatitis C infection is the leading indication for liver transplantation. The Centers for Disease Control and Prevention estimate that the number of annual deaths caused by hepatitis C will triple in the next 10 to 20 years. ²⁴ The majority of diagnoses are made during biochemical or blood donor screening, or when symptoms emerge from advanced chronic hepatitis, cirrhosis, or end-stage liver disease.

In 1988, scientists identified the hepatitis C virus (HCV) as the major causative agent of bloodborne non-A, non-B hepatitis. Since then, they have learned much about the biology, epidemiology, and pathophysiology of hepatitis C.

HCV is a single-stranded RNA virus of the Flaviviridae family, which includes viruses that cause yellow fever, dengue, Japanese encephalitis, and St. Louis encephalitis. Researchers have classified six major strains (or genotypes) of HCV. Athough genotype does not predict the outcome of infection, it predicts the likelihood of treatment success. Therefore genotype should be determined  in all HCV-infected patients before initiation of treatment to determine the duration of therapy and probability of success. Those infected with HCV genotypes 2 and 3 have a high probability of responding to treatment.²⁵

Recognition and Diagnosis: The average incubation period is six to seven weeks after infection with HCV; the range is two to 20 weeks. The patient may be asymptomatic until liver damage occurs. The primary screening test is the enzyme immunoassay (EIA) which can detect the hepatitis C antibody within four to 10 weeks.

Testing for hepatitis C antibody should be continued up to six months after a known exposure to HCV. A second confirmatory test – the RIBA (recombinant immunoblot assay) – can rule out a false-positive EIA result. Besides these antibody tests, qualitative tests, such as hepatitis C RNA testing by polymerase chain reaction (PCR) or branched DNA testing, can determine hepatitis C viral burden, similar to HIV. Quantitative tests for HCV RNA (viral loads) have become the gold standard for monitoring treatments.²⁵

No test can differentiate between acute and chronic infection. A diagnosis of chronic hepatitis C is based on a positive hepatitis C antibody test and elevated liver enzymes (AST and ALT) that persist for more than six months, or by liver biopsy for histological evidence of hepatitis, even with normal serum aminotransferase concentrations. The ALT is often only modestly elevated, and the AST is usually lower than the ALT. A liver biopsy determines the extent of liver involvement.

The Disease Process: Although patient’s are typically asymptomatic and hepatitis C is commonly diagnosed on routine exam years after infection, some patients present with an acute form. These patients may present with vague symptoms, such as fatigue, anorexia, malaise, nausea, vomiting, headache, and neuralgia. Rarely these symptoms are accompanied by fever and hepatomegaly.

HCV presents more commonly as chronic hepatitis after many years of undiagnosed infection. In fact, symptoms may not appear until end-stage liver disease. Seventy-five percent to 85% of those infected with HCV develop chronic infection, while only 2% to 5% of adult patients with acute hepatitis B virus .²⁵ Patients with persistent hepatitis B surface antigen develop chronic hepatitis B and are capable of transmitting the disease to others. On the other hand, all people with hepatitis C antibody are presumed to be infectious.

The history of hepatitis C infection is typically variable. An estimated 10% to 15% of all patients eventually become free of hepatitis C infection. Chronic viremia occurs in 85% to 90% of those who are infected, 70% of whom develop some degree of liver damage. On average, 15 years pass before diagnosis of HCV, 20 years before cirrhosis which occurs in 10% to 20%, and more than 25 years for the onset of hepatocellular carcinoma (HCC).²⁶

According to the American Cancer Society 25% to 50% of primary liver cancers are associated with HBV or HCV infection.  Liver cancer commonly occurs in those with hepatitis C-induced cirrhosis and rarely occurs in HCV-infected patients without cirrhosis. The risk of cancer greatly increases in those who have both hepatitis C and HIV or chronic hepatitis B infection, and who drink alcohol. The pathogenesis of hepatitis C infection is not well known. Liver necrosis, scarring, and Kupffer cell hyperplasia and phagocytosis all occur during acute infection.

Persistent hepatitis C infection in the absence of liver disease appears to result from either the virus’s ability to mutate and escape the body’s immunological control or to replicate outside the liver. Chronic hepatitis C may eventually progresses to cirrhosis. Cirrhosis, an inflammatory disease caused by fibrosis and nodular regeneration of liver tissue, is a slow, gradual process. The liver may become larger or smaller than normal, and is firm or hard when palpated.

Obstruction caused by cirrhosis can lead to portal hypertension. Elevated pressure in the liver causes collateral vessels to open up between the portal and systemic veins. Blood that has been shunted through this collateral system has not circulated through the liver where toxins and other harmful substances are normally removed, causing these noxious substances to accumulate. Long-term portal hypertension is associated with esophageal varices, splenomegaly, ascites, and hepatic encephalopathy.²⁸

Factors that influence the progression of fibrosis are age at the time of infection, gender, alcohol use, and viral coinfection. Patients who acquire hepatitis C after age 40 have more aggressive disease while children commonly have a mild form. Rapidly progressive disease is less common in women than men. Those who abuse alcohol are 15-times more likely to develop cirrhosis than those who abstain.²¹

Preventing Transmission: Hepatitis C is a bloodborne pathogen. Exposure through injection drug use poses the highest risk. According to the CDC, of people who inject drugs for at least five years, 60% to 80 % become infected with HCV compared to about 30 % who become infected with HIV. Other methods of exposure include transfusion and organ transplantation (however, testing for HCV has greatly reduced the risk; as of 2001, the risk of HCV infection from a unit of transfused blood is less than one per million transfused units), hemodialysis, nasal cocaine ingestion, occupational exposure to contaminated needlesticks or mucosal exposure to HCV-positive blood, and high-risk sexual practices. Sexual transmission is associated with multiple sex partners, prolonged exposure, and commonly the presence of other risk factors, such as injection drug use and coinfection with HIV.

While it is possible for HCV to be transmitted from any percutaneous exposure to blood, exposures such as tattooing, body piercing, or acupuncture have not been shown to place people at increased risk for infection.²⁹

Clotting factor concentrates, which are plasma-derived products used to treat individuals with hemophilia, posed a high risk for HCV infection before the use of virus inactivation procedures that were introduced in 1985 and 1987. Except for one outbreak of hepatitis C from a single type of contaminated IV immunoglobulin, there have been no other outbreaks of HCV from these products in the US. Currently, all immune globulin products undergo a virus inactivation procedure or test negative for HCV before release.²⁹

According to the CDC about 6% of infants become infected through vertical transmission of the disease from infected mothers. These infants appear to be healthy during the first years of life. Neither breastfeeding or the mode of delivery is associated with transmission so there is no need to avoid breastfeeding and no need for cesarean delivery based on HCV status.²⁹

Shared personal care items that can induce bleeding, such as toothbrushes and razors, have been proposed as possible vehicles of HCV transmission. Standard precautions should always be observed to prevent the spread of infection.

Treatment: Treatment success has improved dramatically in recent years with the advent of combination therapy using pegylated interferon and ribavirin. This combination therapy, which is the treatment of choice for patients with HCV, has demonstrated  sustained virologic response rates (undetectable HCV viral load) of  45% to 80%.²⁵

Approximately 75% of those treated with combination therapy experience adverse effects including neutropenia, thrombocytopenia, depression, hypothyroidism or hyperthyroidism, irritability, concentration and memory disturbances, visual disturbances, fatigue, muscle aches, headaches, nausea, vomiting, skin irritation, low-grade fever, weight loss, insomnia, hearing loss, tinnitus, interstitial fibrosis, hair loss, rash, hemolytic anemia, and gout.

Adverse effects are typically more severe during the initial weeks of therapy. They can commonly be managed with analgesics, such as acetaminophen in doses less than 2 grams per day or nonsteroidal anti-inflammatory agents; antidepressants, such as serotonin reuptake inhibitors; and, occasionally growth factors such as epoetin. Birth defects are associated with ribavarin so strict contraception methods must be used during and for 6 months after treatment.²⁵

Liver transplantation is sometimes indicated for those with HCV-induced cirrhosis.

Antiviral agents or immune globulin are not recommended for HCV postexposure prophylaxis. Instead the CDC recommends baseline testing of the source patient for HCV. For the patient who was exposed to an HCV-positive source, baseline and follow-up testing should be performed. Testing should include baseline testing for HCV and ALT activity, then follow-up testing  for HCV and ALT activity should take place in 4 to 6 months. If earlier test results are needed, testing for HCV RNA may be performed at 4 to 6 weeks. All supplemental HCV testing must be confirmed by enzyme immunoassay.³⁰

HIV/AIDS — An Update

In 1996, monumental advances unsettled perceptions of AIDS and altered the medical treatment:³¹ a revolutionary understanding of the pathogenesis of HIV infection, the ability to measure the plasma viral burden, and the introduction of more powerful drugs called HAART (highly active antiretroviral therapy). As a result, the goal of therapy changed to incorporate the detection of viral burden. The goal of therapy today is to reduce the viral load (preferably to less than 20 c/mL) for as long as possible. Patients are offered aggressive treatment early in the disease course, including at the time of initial seroconversion to HIV-antibody positive—a treatment approach unforeseeable in the recent past. Earlier in the epidemic, treatment was limited to monotherapy and delayed until clear evidence of immune system impairment.

The number of AIDS cases in the US grew rapidly during the 1980s, peaked in 1993, and sharply declined in 1996. But the decline slowed in the following years. The decreases in incidence and deaths are primarily due to the widespread use of HAART, which slows both the progression of HIV infection to AIDS and of AIDS to death. Because HAART is so helpful, new cases of AIDS are more likely to be related to failure of HAART or lack of access to prevention, HIV testing and counseling, and medical and social services that predominantly affect the poor, uniformed, or disenfranchised members of our society.

Since the implementation of HAART, the number of persons diagnosed with AIDS and the number of deaths among persons with AIDS has declined substantially. As a result, the number of persons living with AIDS has increased. As of December 2003, an estimated 395,317 persons in the 50 US states are living with AIDS; in Puerto Rico an estimated 9,798. The overall incident rate in the continental US is 15 per 100,000 people; and 27.5 per 100,000 in Puerto Rico.³³

In the early 1990s, before perinatal prevention treatments were available, between 1,000 and 2,000 infants were born with HIV every year. Since these treatments have become available, perinatal infections have decreased by 66%.³⁴

Declines in the incidence of AIDS and deaths from AIDS, first reported in 1996, provide evidence of the effects of new treatment regimens. However declines did not continue substantially after 1997, supporting that behavioral changes must also occur to reduce incidence of infection.

Recognizing and Diagnosing HIV Infection: Identification of patients with primary HIV infection provides several important opportunities to reduce transmission of HIV. Clinicians can counsel newly infected people who have recently engaged in high-risk activity for the transmission of HIV to prevent subsequent transmission and to notify partners of their HIV risk. Recently infected people fuel a substantial portion of the epidemic of new HIV infections.

People with primary HIV infections have high levels of plasma-HIV viremia and can transmit larger quantities of infectious virus through semen and vaginal fluids than patients with lower plasma levels. In addition, a substantial number of newly infected people acquire drug-resistant viral strains during their initial exposure. This is called primary resistance.³⁵ Patients with primary resistance already have drug-resistant strains of virus at their time of diagnosis. Secondary resistance will also develop over time as an effect of naturally occurring mutations, adherence problems, or poor selection of treatment regimens. People with primary resistance require testing, counseling, medical and social services, and contract tracing just like everybody else, but their therapeutic options are limited from the start.

HIV Testing: