Diseases Associated with Person-to-Person Contact Flashcards
Diphtheria Geographic risk, prevention, transmission, possible symptoms and appropriate referral/triage of:
Endemic in many countries in Africa, South America, Asia, the South Pacific, the Middle East, and Eastern Europe and in Haiti and the Dominican Republic.
Prevention: All travelers should be up-to-date with diphtheria toxoid vaccine before departure. Routine booster doses with Td (tetanus-diphtheria) should be given to all adults every 10 years. This booster is particularly important for travelers who will live or work with local populations in countries where diphtheria is endemic.
Transmission: Person-to-person through oral or respiratory droplets, close physical contact, and rarely, by fomites. Cutaneous diphtheria is common in tropical countries, and contact with discharge from skin lesions may transmit infection in these environments
Symptoms:
The incubation period is 2–5 days (range, 1–10 days). Affected anatomic sites include the mucous membrane of the upper respiratory tract (nose, pharynx, tonsils, larynx, and trachea [respiratory diphtheria]), skin (cutaneous diphtheria), or rarely, mucous membranes at other sites (eye, ear, vulva). Nasal diphtheria can be asymptomatic or mild, with a blood-tinged discharge. Respiratory diphtheria has a gradual onset and is characterized by a mild fever (rarely >101°F [38.3°C]), sore throat, difficulty swallowing, malaise, loss of appetite, and if the larynx is involved, hoarseness. The hallmark of respiratory diphtheria is a pseudomembrane that appears within 2–3 days of illness over the mucous lining of the tonsils, pharynx, larynx, or nares and that can extend into the trachea. The pseudomembrane is firm, fleshy, grey, and adherent; it will bleed after attempts to remove or dislodge it. Fatal airway obstruction can result if the pseudomembrane extends into the larynx or trachea, or if a piece of it becomes dislodged.
Treatment: Patients with respiratory diphtheria require hospitalization to monitor response to treatment and manage complications. Equine diphtheria antitoxin (DAT) is the mainstay of treatment and is administered after specimen testing, without waiting for laboratory confirmation. An antibiotic (erythromycin or penicillin) should be used to eliminate the causative organisms, stop exotoxin production, and reduce communicability. Supportive care (airway, cardiac monitoring) is required. Antimicrobial prophylaxis (erythromycin or penicillin) is recommended for close contacts of patients.
Hepatitis B Geographic risk, prevention, transmission, possible symptoms and appropriate referral/triage of
An estimated 240 million people have chronic HBV infection globally. Nevertheless, no data show the specific risk of infection with HBV among US travelers. Published reports of travelers acquiring hepatitis are rare, and the risk for travelers who do not have high-risk behaviors or exposures is low. The risk for HBV infection in travelers may be higher in countries where the prevalence of chronic HBV infection is high or intermediate; expatriates, missionaries, and long-term development workers may be at increased risk for HBV infection in such countries. All travelers should be aware of how HBV is transmitted and take measures to minimize their exposures.
Prevention: Vaccine As part of the pre-travel education process, all travelers should be counseled and given information about the risks for hepatitis B and other bloodborne pathogens from contaminated equipment or items used during medical, dental, or cosmetic procedures; blood products; injection drug use; any activities or procedures that involve piercing the skin or mucosa; or unprotected sexual activity, and should be informed about prevention measures. When seeking medical or dental care or cosmetic procedures (such as tattooing or piercing), travelers should be alert to the use of equipment that has not been adequately sterilized or disinfected, reuse of contaminated equipment, and unsafe injecting practices (such as reuse of disposable needles and syringes). HBV and other bloodborne pathogens can be transmitted if tools are not sterile or if personnel do not follow proper infection control procedures. Travelers should consider the health risks when receiving medical or dental care. The health risks should be strongly considered when deciding to obtain a tattoo or body piercing in areas where adequate sterilization or disinfection procedures might not be available or practiced.
Transmission: HBV is transmitted by contact with contaminated blood, blood products, and other body fluids (such as semen). Activities associated with transmission include any that may increase the likelihood of contaminated blood or body fluid exposure. Travelers may be at increased risk due to engaging in casual and unprotected sex, having medical procedures in areas where blood may not be screened, or even through obtaining tattoos or having acupuncture.
Symptoms:
HBV infection primarily affects the liver. Typically, the incubation period for hepatitis B is 90 days (range, 60–150 days). The usual signs and symptoms include malaise, fatigue, anorexia, nausea, vomiting, abdominal pain, and jaundice. In some cases skin rashes, joint pain, and arthritis may occur. Among people aged ≥5 years, 30%–50% will develop signs and symptoms during acute infection. In children aged <5 years and immunocompromised adults, acute HBV infection is typically asymptomatic. The overall case-fatality ratio of acute hepatitis B is approximately 1%.
Acute hepatitis B progresses to chronic HBV infection in 30%–90% of people infected as infants or young children and in <5% of people infected during adolescence or adulthood. Chronic infection with HBV may result in chronic liver disease, including cirrhosis and liver cancer.
Treatment:
No specific treatment is available for acute hepatitis B. Supportive treatment, including hospitalization, may be indicated for some people with severe clinical manifestations. Antiretroviral drugs are approved to treat chronic hepatitis B.
Hepatitis C Geographic risk, prevention, transmission, possible symptoms and appropriate referral/triage of
Approximately 2%–3% (130–170 million) of the world’s population has been infected with HCV. In many developed countries, including the United States, the prevalence of HCV infection is 2%) in several countries in Latin America, Eastern Europe, and the former Soviet Union, and certain countries in Africa, the Middle East, and South Asia; the prevalence is reported to be highest (>10%) in Egypt. The most frequent mode of transmission in the United States is through sharing drug-injection equipment. Travelers’ risk for contracting HCV infection is generally low, but travelers should exercise caution when traveling to countries where the prevalence of HCV infection is ≥2%, as the following activities can result in blood exposure: Receiving blood transfusions that have not been screened for HCV Having medical or dental procedures Activities such as acupuncture, tattooing, public shaving, or injection drug use in which equipment has not been adequately sterilized or disinfected, or in which contaminated equipment is reused Working in health care fields (medical, dental, or laboratory) that entail direct exposure to human blood
Prevention: No vaccine is available to prevent HCV infection, nor does immune globulin provide protection. Before traveling, people should check with their health care providers to understand the potential risk of infection and any precautions they should take. When seeking medical or dental care, travelers should be alert to the use of medical, surgical, and dental equipment that has not been adequately sterilized or disinfected, reuse of contaminated equipment, and unsafe injection practices (such as reuse of disposable needles and syringes). HCV and other bloodborne pathogens can be transmitted if instruments are not sterile or the clinician does not follow other proper infection-control procedures (washing hands, using latex gloves, and cleaning and disinfecting surfaces and instruments). There are still a few areas of the world, such as parts of sub-Saharan Africa, where blood donors may not be screened for HCV. Travelers should be advised to consider the health risks if they are thinking about getting a tattoo or body piercing or having a medical procedure in areas where adequate sterilization or disinfection procedures might not be practiced. Travelers should be advised to seek testing for HCV upon return if they received blood transfusions or sustained other blood exposures for which they could not assess the risks.
Transmission: Transmission of HCV is bloodborne and occurs mainly through sharing drug-injection equipment, from transfusion of unscreened blood, or from untreated clotting factors. In developing countries, unsterile medicinal and other injection practices account for many HCV infections. Although infrequent, HCV can be transmitted through other procedures that involve blood exposure (such as tattooing) and during sexual contact.
Symptoms: Most people (80%) with acute HCV infection have no symptoms. If symptoms do occur, they may include loss of appetite, abdominal pain, fatigue, nausea, dark urine, and jaundice. Of those who develop chronic HCV infection, the most common symptom is fatigue; severe liver disease develops in about 10%–20% of infected people. HCV is a major cause of cirrhosis and hepatocellular cancer and is the leading reason for liver transplantation in the United States.
Treatment: Treatment for hepatitis C is rapidly evolving. Currently, sustained virologic response (SVR), which is considered a cure, is achieved in 50% of patients taking the previous standard treatment of pegylated interferon and ribavirin for 24–48 weeks. In May 2011, 2 new protease inhibitors, telaprevir and boceprevir, were approved to treat hepatitis C in the United States. When these drugs were added to a regimen of pegylated interferon and ribavirin in clinical trials, SVR rates increased to 75% for those also receiving telaprevir and to 63% for those also receiving boceprevir among people with HCV genotype 1 (the most common genotype in the United States). Treatment is most effective for people diagnosed within the first year of infection. However, this is difficult as serologic markers of acute infection are lacking and most acute cases are only mildly symptomatic or asymptomatic.
Influenza Geographic risk, prevention, transmission, possible symptoms and appropriate referral/triage of
Seasonal Influenza Influenza season varies geographically and by climate. In temperate climates, influenza activity generally occurs during the winter months. The influenza season in the Northern Hemisphere may begin as early as October and can extend until May. The influenza season in the Southern Hemisphere may begin in April and last through September. In tropical and subtropical areas, influenza may occur throughout the year, but most countries will have defined seasonal peaks.
Prevention: Vaccine Measures that may help prevent influenza virus infection and other infections during travel include avoiding contact with others while sick; avoiding close contact with sick people; washing hands often with soap and water (where soap and water are not available, using an alcohol-based hand sanitizer containing ≥60% alcohol); avoiding touching one’s eyes, nose, and mouth; and covering coughs and sneezes with a tissue, then disposing of the tissue. In countries where HPAI H5N1 virus outbreaks are occurring among poultry, travelers should avoid markets and farms where live poultry are sold or raised, avoid contact with dead poultry, and not drink chicken blood or eat undercooked chicken.
Transmission: Influenza viruses spread from person to person, primarily through large-particle respiratory droplet transmission (such as when an infected person coughs or sneezes near a susceptible person). Transmission via large-particle droplets requires close contact between the source and the recipient, because droplets generally travel only short distances (approximately 6 feet or less) through the air, before settling onto surfaces. Airborne transmission via small-particle aerosols in the vicinity of the infectious person may also occur. Indirect transmission through hand transfer of influenza virus from virus-contaminated surfaces to mucosal surfaces of the face (such as the nose or mouth) may also occur. However, the relative contribution of the different modes of transmission to the spread of influenza viruses is unclear. Most healthy adults who are ill with influenza shed the virus in the upper respiratory tract and are infectious from the day before symptom onset to approximately 5–7 days after symptom onset. Generally, people are most contagious in the 3 days after illness onset. Children and those who are immunocompromised or severely ill, including those who are hospitalized, may shed influenza virus for 10 days or more after the onset of symptoms. Seasonal influenza viruses have rarely been detected from nonrespiratory sources such as diarrheal stool or blood.
Symptoms: Uncomplicated influenza illness is characterized by the abrupt onset of signs and symptoms that include fever, muscle aches, headache, malaise, nonproductive cough, sore throat, vomiting, and rhinitis. Illness without fever can occur, especially in elderly people. Children are more likely than adults to also experience nausea, vomiting, or diarrhea when ill with influenza. Physical findings are predominantly localized to the respiratory tract and include nasal discharge, pharyngeal inflammation without exudates, and occasionally rales on chest auscultation. The incubation period is usually 1–4 days after exposure. Influenza illness typically resolves within 1 week for most previously healthy children and adults who do not receive antiviral medication, although cough and malaise can persist for >2 weeks, especially in the elderly. Complications of influenza virus infection include primary influenza viral pneumonia, secondary bacterial pneumonia, exacerbation of underlying medical conditions (such as pulmonary and cardiac disease), encephalopathy, myocarditis, myositis, or coinfections with other viral or bacterial pathogens.
Treatment: Early antiviral treatment can shorten the duration of fever and other symptoms and reduce the risk of complications from influenza. Antiviral treatment is recommended as early as possible for any patient with confirmed or suspected influenza who is hospitalized; has severe, complicated, or progressive illness; or is at a higher risk for influenza complications. Antiviral treatment can also be considered for any previously healthy patient not at high risk of complications, with confirmed or suspected influenza, if treatment can be initiated within 48 hours of illness onset. Although antiviral therapy is ideally initiated within the first 48 hours of illness, for hospitalized patients, those with severe illness, or those at higher risk of complications, antiviral therapy may still be beneficial if started >48 hours after illness onset. Two neuraminidase inhibitors are available for antiviral treatment and chemoprophylaxis of influenza: oral oseltamivir (Tamiflu) and inhaled zanamivir (Relenza). Both are active against influenza A and B viruses. Oseltamivir is approved for treatment and chemoprophylaxis of patients aged ≥1 year. Zanamivir is approved for treatment in those aged ≥7 years and for chemoprophylaxis in those aged ≥5 years (Table 3-05). Two other medications, amantadine and rimantadine, which belong to the adamantane class of antivirals, are active only against influenza A but not influenza B viruses and are not recommended for treatment or chemoprophylaxis because of widespread viral resistance among circulating influenza A viruses. People at increased risk for complications of influenza should discuss antiviral treatment and chemoprophylaxis with their health care provider before travel, if traveling to areas where influenza activity is occurring. The effectiveness of antivirals for treating HPAI H5N1 virus infections has not been fully studied, although limited observational evidence suggests that early treatment has been associated with lower risk of death. CDC recommends treatment with oseltamivir for human infection with avian or swine influenza A viruses.
Measles Geographic risk, prevention, transmission, possible symptoms and appropriate referral/triage of:
The number of reported measles cases in the United States has declined from nearly 900,000 annually in the early 1940s to an average of 83 cases annually from 2001 through 2011. As a result of high vaccination coverage and better measles control in the Americas, in 2000, measles was declared eliminated (no disease transmission for at least 12 months) in the United States. Indigenous measles virus circulation was interrupted in 2002 in the rest of the Western Hemisphere. However, measles virus continues to be imported into the United States from other parts of the world. Globally, an estimated 20 million measles cases occur each year. Given the large global incidence and high communicability of the disease, travelers may be exposed to the virus in almost any country they visit, particularly those outside the Western Hemisphere, where measles is endemic or where large outbreaks are occurring. Of the 222 reported measles cases in the United States in 2011, 200 (90%) were associated with importations from other countries, including 72 direct importations (52 among US residents traveling abroad and 20 among foreign visitors). The largest percentage of importations (46%) was among people who acquired the disease in Europe. However, importations consistently occur from other countries and regions, including India and the Philippines.
Prevention: Vaccine
Transmission: Measles is transmitted primarily from person to person by large respiratory droplets but can also spread by the airborne route as aerosolized droplet nuclei. Infected people are usually contagious from 4 days before until 4 days after rash onset. Measles is one of the most contagious viral diseases known; secondary attack rates are >90% in susceptible household and institutional contacts. Humans are the only natural host for sustaining measles virus transmission, which makes global eradication of measles feasible.
Symptoms: The incubation period ranges from 7 to 21 days from exposure to onset of fever; rash usually appears about 14 days after exposure. Symptoms include prodromal fever that can rise as high as 105°F (40.6°C), conjunctivitis, coryza (runny nose), cough, and small spots with white or bluish-white centers on an erythematous base on the buccal mucosa (Koplik spots). A characteristic red, blotchy (maculopapular) rash appears on the third to seventh day after the prodromal symptoms appear. The rash begins on the face, becomes generalized, and lasts 4–7 days. Common complications include diarrhea (8%), middle ear infection (7%–9%), and pneumonia (1%–6%). Encephalitis, which can result in permanent brain damage, occurs in approximately 1 per 1,000–2,000 cases of measles. Subacute sclerosing panencephalitis (SSPE), a rare but serious degenerative central nervous system disease caused by a persistent infection with a defective measles virus, is estimated to occur in 1 per 100,000 cases. However, among people who became infected with measles during the 1989–1991 measles resurgence in the United States, the estimated risk of SSPE was 22 per 100,000 reported measles cases. SSPE is manifested by mental and motor deterioration that starts an average of 7–10 years after measles virus infection (most frequently in children who were infected at age
Treatment:
Treatment is supportive. The World Health Organization recommends vitamin A for all children with acute measles, regardless of their country of residence, to reduce the risk of complications. Vitamin A is administered once a day for 2 days at the following doses:
- 50,000 IU for infants aged <6 months
- 100,000 IU for infants aged 6–11 months
- 200,000 IU for children aged ≥12 months
An additional (third) age-specific dose of vitamin A should be given 2–4 weeks later to children with clinical signs and symptoms of vitamin A deficiency. Parenteral and oral formulations of vitamin A are available in the United States.
Pertussis Geographic risk, prevention, transmission, possible symptoms and appropriate referral/triage of:
Pertussis is endemic worldwide, even in areas with high vaccination rates. From 2004 through 2010, the annual number of reported pertussis cases in the United States ranged from approximately 8,000 to >27,000. Disease rates are highest among young children in countries where vaccination coverage is low, which is primarily in the developing world. In developed countries, the incidence of pertussis is highest among infants too young to be vaccinated. Immunity from childhood vaccination and natural disease wanes with time; therefore, adolescents and adults who have not received a tetanus-diphtheria-pertussis (Tdap) booster vaccination can become infected or reinfected. US travelers are not at increased risk for disease specifically because of international travel, but they are at risk if they come in close contact with infected people. Infants too young to be protected by a complete vaccination series are at highest risk for severe pertussis that requires hospitalization.
Prevention: Vaccine
Symptoms: In classic disease, mild upper respiratory tract symptoms begin 7–10 days (range, 6–21 days) after exposure, followed by a cough that becomes paroxysmal. Coughing paroxysms can vary in frequency and are often followed by vomiting. Fever is absent or minimal. The clinical case definition for pertussis includes cough for ≥2 weeks with paroxysms, whoop, or posttussive vomiting. Disease in infants aged
Treatment:
Macrolide antibiotics (azithromycin, clarithromycin, and erythromycin) are recommended for the treatment of pertussis in people aged ≥1 month; for infants aged <1 month, azithromycin is the preferred antibiotic. Antimicrobial therapy with a macrolide antibiotic administered <3 weeks after cough onset can limit transmission to others. Postexposure prophylaxis is recommended for close contacts of cases and for people at high risk of developing severe disease (such as infants and those who will have contact with young infants). The recommended agents and dosing regimens for prophylaxis are the same as for the treatment of pertussis.
Pneumococcal Disease Geographic risk, prevention, transmission, possible symptoms and appropriate referral/triage of:
Occurs worldwide, but prevalence is higher in developing than in industrialized countries. Risk is highest in young children, the elderly, and those with chronic illnesses or immune suppression.
Prevention: Vaccine
Transmission: Person to person through close contact via respiratory droplets.
Clinical Presentation: Sudden onset of fever and malaise, cough, pleuritic chest pain, purulent or blood-tinged sputum. In the elderly, fever, shortness of breath, or altered mental status may be initial symptoms. Pneumococcal meningitis may present as a stiff neck, headache, lethargy, or seizures.
Treatment: Empiric therapy depends on the syndrome. Many strains are resistant to penicillin, cephalosporins, and macrolides, so definitive treatment should be targeted on the basis of antimicrobial susceptibility results. In the United States and other countries where β-lactam resistance is common, the initial regimen for pneumococcal meningitis might include vancomycin or a fluoroquinolone, plus a third-generation cephalosporin.
Rubella Geographic risk, prevention, transmission, possible symptoms and appropriate referral/triage of:
Occurs worldwide outside the Americas. In the United States, endemic rubella virus transmission has been eliminated, but it continues to be imported.
Prevention: Vaccine
Transmission: Person-to-person contact or droplets shed from the respiratory secretions of infected people. Transmission from mother to fetus can also occur, resulting in an infant being born with congenital rubella syndrome.
Symptoms: Average incubation period is 14 days (range, 12–23 days). Usually presents as a nonspecific, maculopapular, generalized rash that lasts ≤3 days with generalized lymphadenopathy. Rash may be preceded by low-grade fever, malaise, anorexia, mild conjunctivitis, runny nose, and sore throat. Asymptomatic rubella virus infections are common. Infection during early pregnancy can lead to miscarriage, fetal death, or severe birth defects known as congenital rubella syndrome.
Treatment: Supportive care.
Sexually transmitted disease Geographic risk, prevention, transmission, possible symptoms and appropriate referral/triage of:
STDs are among the most common infectious diseases. Annually, an estimated 448 million infections occur worldwide, and 19 million infections occur in the United States. Some STDs are more prevalent in developing countries (chancroid, lymphogranuloma venereum, granuloma inguinale [donovanosis]) or in specific regions (gonorrhea with treatment failure and decreased susceptibility to cephalosporins in East Asia) and may be imported into developed countries by travelers returning from such locales. Casual sexual relationships occur frequently during travel to foreign countries; 5%–50% of travelers report casual sex with a new partner while abroad. In addition, commercial sex in various destinations, such as Southeast Asia, attracts many foreign travelers. Commercial sex workers in some regions have high rates of STDs, including HIV, and travelers who have sex with them risk acquiring these infections. Knowledge of the clinical presentation, frequency of infection, and antimicrobial resistance patterns is needed to manage STDs that occur in travelers. Assessing risk for men who have sex with men is important because of the recent increased rates of infectious syphilis, gonorrhea with treatment failure and decreased susceptibility to cephalosporins, and lymphogranuloma venereum in various geographic locations.
Prevention: The prevention and control of STDs are based on education, counseling, early identification, and treatment. Specific messages to avoid acquiring or transmitting STDs should be part of the health advice given to travelers. Abstinence or mutual monogamy is the most reliable way to avoid acquiring and transmitting STDs. For people whose sexual behaviors place them at risk for STDs, correct and consistent use of the male latex condom can reduce the risk of HIV infection and many common STDs, including chlamydia, gonorrhea, and trichomoniasis. Preventing lower genital tract infections might reduce the risk of pelvic inflammatory disease in women. Condoms might protect against genital herpes, syphilis, and chancroid, although data are limited. Only water-based lubricants (such as K-Y Jelly or glycerin) should be used with latex condoms because oil-based lubricants (such as petroleum jelly, shortening, mineral oil, or massage oil) can weaken latex condoms. Spermicides containing nonoxynol-9 are not recommended for STD/HIV prevention, as nonoxynol-9 can increase the risk of HIV transmission. Contraceptive methods that are not mechanical barriers do not protect against HIV or other STDs. Prompt evaluation of sexual partners is necessary to prevent reinfection and disrupt transmission of many STDs. Preexposure vaccination is among the most effective methods for preventing some STDs. Two human papillomavirus (HPV) vaccines are available and licensed for girls and women aged 9–26 years to prevent cervical precancers and cancers: the quadrivalent HPV and the bivalent HPV vaccine. The quadrivalent vaccine also prevents genital warts and is recommended for boys and men aged 9–26 years as well as girls and women (see the Human Papillomavirus section in this chapter). Preexposure vaccination against hepatitis A and B is recommended, as these infections can be sexually transmissible. Hepatitis A vaccine is recommended for all unvaccinated injection drug users and sexually active men who have sex with men. Hepatitis B vaccine is recommended for all unvaccinated men who have sex with men, as well as people who have a history of an STD, have had >1 sexual partner in the previous 6 months, use injection drugs, or have a sex partner who uses injection drugs. However, all travelers should be considered candidates for both these vaccines. Travelers, particularly those at high risk for acquiring HIV infection (such as men who have sex with men), may consider discussing preexposure prophylaxis with their health care provider Transmission: Many infections may be asymptomatic (chlamydia, gonorrhea), so screening for these infections at anatomic sites of contact and serologic testing for syphilis should be encouraged among travelers who present in clinic concerned they may have acquired an STD. Any traveler who might have been exposed and who develops vaginal, urethral, or rectal discharge, an unexplained rash or genital lesion, or genital or pelvic pain should be advised to cease sexual activity and promptly seek medical evaluation. Some systemic infections are acquired through sexual transmission (hepatitis A, hepatitis B, hepatitis C, HIV, syphilis). Because many travelers do not volunteer a history of sexual contact during travel, clinicians should inquire about sexual exposures when caring for returned travelers.
Treatment: Evaluation, management, and follow-up of STDs should be based on standard guidelines (CDC and the World Health Organization), and the prevalence of antimicrobial resistance in different geographic areas should be considered. Early detection and treatment are important. STDs can often result in serious and long-term complications, including pelvic inflammatory disease, infertility, stillbirths and neonatal infections, genital cancers, and an increased risk for HIV acquisition and transmission.
Tuberculosis Geographic risk, prevention, transmission, possible symptoms and appropriate referral/triage of:
Globally, nearly 9 million new TB cases and approximately 1.5 million TB-related deaths occur each year. TB occurs throughout the world, but the incidence varies (see Map 3-13). In the United States, the annual incidence is <4 per 100,000 population, but in some countries in sub-Saharan Africa and Asia, the annual incidence is several hundred per 100,000.
Drug-resistant TB is of increasing concern. Multidrug-resistant (MDR) TB is resistant to the 2 most effective drugs, isoniazid and rifampin. Extensively drug-resistant (XDR) TB is resistant to isoniazid and rifampin, any fluoroquinolone, and ≥1 of 3 injectable second-line drugs (amikacin, kanamycin, or capreomycin). MDR TB is less common than drug-susceptible TB, but nearly 440,000 new cases of MDR TB are diagnosed each year, and some countries have proportions of MDR TB as high as 20% (see Map 3-14). MDR and XDR TB are of particular concern among HIV-infected or other immunocompromised people. As of October 2011, XDR TB had been reported in 77 countries (see Map 3-15).
Travelers who anticipate possible prolonged exposure to TB (such as those who would spend time in hospitals, prisons, or homeless shelters) or those who stay for years in an endemic country should have a 2-step tuberculin skin test (TST) or a single interferon-γ release assay (IGRA), either the QuantiFERON TB test (Gold In-Tube version) or T-SPOT.TB test, before leaving the United States (see Perspectives: Tuberculin Skin Testing of Travelers, later in this chapter). If the predeparture test result is negative, a single TST or IGRA should be repeated 8–10 weeks after returning from travel. Because people with HIV infection or other immunocompromising conditions are more likely to have an impaired response to either a skin or blood test, travelers should inform their physicians about such conditions. Except for those with impaired immunity, travelers who have already been infected are less likely to be reinfected.
The risk of TB transmission on an airplane does not appear to be higher than in any other enclosed space. To prevent TB transmission, people who have infectious TB should not travel by commercial airplanes or other commercial conveyances. The World Health Organization (WHO) has issued guidelines for notifying passengers who might have been exposed to TB aboard airplanes. Passengers concerned about possible exposure to TB should see their primary health care provider for evaluation.
Bovine TB (M. bovis) is a risk in travelers who consume unpasteurized dairy products in countries where M. bovis in cattle is common. Mexico is a common place of infection for US travelers.
Prevention:
Travelers should avoid exposure to TB patients in crowded environments (such as hospitals, prisons, or homeless shelters). Travelers who will be working in hospitals or health care settings where TB patients are likely to be encountered should be advised to consult infection control or occupational health experts about procedures for obtaining personal respiratory protective devices (such as N-95 respirators), along with respirator selection and training.
Based on WHO recommendations, Bacillus Calmette-Guérin (BCG) vaccine is used once at birth in most developing countries to reduce the severe consequences of TB in infants and children. However, BCG vaccine has variable efficacy in preventing the adult forms of TB and interferes with testing for LTBI with the TST. Therefore, BCG is not routinely recommended for use in the United States. Recently, some experts have advocated BCG vaccination for people who are likely to be exposed to MDR or XDR TB patients in settings where the TB infection control measures recommended in the United States are not fully implemented. BCG may offer some protection in this circumstance; however, people who receive BCG vaccination must follow all recommended TB infection control precautions to the extent possible. Additionally, IGRA is preferred over the TST for pre- and post-travel testing in people vaccinated with BCG.
To prevent infections due to M. bovis, travelers should also avoid eating or drinking unpasteurized dairy products.
Transmission:
Tuberculosis (TB) transmission occurs when a contagious patient coughs, spreading bacilli through the air. Bovine TB (caused by the closely related Mycobacterium bovis) can be transmitted by consuming contaminated, unpasteurized dairy products from infected cattle.
Symptoms:
TB disease can affect any organ but most commonly occurs in the lungs (70%–80%). Common TB symptoms include prolonged cough, fever, decreased appetite, weight loss, night sweats, and coughing up blood (hemoptysis). The most common sites for TB outside the lungs are the lymph nodes, chest-wall lining, bones and joints, brain and spinal cord lining (meningitis), kidneys, bladder, and genitalia.
Infection is manifested by a positive TST or IGRA result, which usually occurs 8–10 weeks after exposure. Overall, only 5%–10% of people progress from infection to disease during their lifetime. In the remainder, the infection remains in a latent state (latent TB infection or LTBI). However, the risk of progression is much higher in immunosuppressed people (8%–10% per year in HIV-infected people not receiving antiretroviral therapy). In recent years, people who are receiving tumor necrosis factor-α inhibitors to treat rheumatoid arthritis and other chronic inflammatory conditions have also been found to be at increased risk for disease progression. LTBI is an asymptomatic condition, and people with LTBI do not transmit TB. Progression to disease can occur weeks to decades after initial infection.
Treatment:
People with LTBI can be treated to prevent progression to TB disease. American Thoracic Society (ATS)/CDC guidelines for treatment of LTBI recommend 9 months of isoniazid as the preferred treatment. The combination regimen of isoniazid and rifapentine given as 12 weekly doses using directly observed therapy is recommended as equivalent to 9 months of isoniazid for treating LTBI in otherwise healthy patients aged ≥12 years who are at higher risk of developing active TB, for example after recent exposure to contagious TB. For people who have been exposed to isoniazid-resistant, rifampin-susceptible TB or who cannot tolerate isoniazid, 4 months of rifampin is a reasonable alternative. Travelers who suspect that they have been exposed to TB should inform their health care provider of the possible exposure and receive medical evaluation. CDC and ATS have published guidelines for targeted testing and treatment of LTBI. Recent data from WHO suggest that drug resistance is relatively common in some parts of the world. Travelers who have TST or IGRA conversion associated with international travel should consult experts in infectious diseases or pulmonary medicine.
TB disease is treated with a multiple-drug regimen administered by directly observed therapy for 6–9 months (usually isoniazid, rifampin, ethambutol, and pyrazinamide for 2 months, followed by isoniazid and rifampin for an additional 4 months) if the TB is not MDR TB. MDR TB treatment is more difficult, requiring 4–6 drugs for 18–24 months; it should be managed by an expert in MDR TB. ATS/CDC/Infectious Diseases Society of America have published guidelines on TB treatment.
Varicella Geographic risk, prevention, transmission, possible symptoms and appropriate referral/triage of:
Varicella occurs worldwide. In temperate climates, varicella tends to be a childhood disease, with peak incidence among preschool and school-aged children and during late winter and early spring. In tropical climates, infection tends to occur later during childhood and adolescence, resulting in higher susceptibility among adults than in temperate climates. Varicella vaccine is routinely used to vaccinate healthy children in only some countries, including the United States, Australia, Canada, Costa Rica, Germany, Greece, Korea, Qatar, Saudi Arabia, Spain, Switzerland, United Arab Emirates, and Uruguay. With the implementation of the varicella vaccination program in the United States, substantial declines have occurred in disease incidence, and although varicella is still endemic, the risk of exposure to varicella zoster virus is higher in most other parts of the world than it is in the United States. Additionally, exposure to herpes zoster poses a risk for varicella in susceptible travelers, although localized herpes zoster is much less infectious than varicella. Travelers at highest risk for severe varicella are infants, immunocompromised people, or pregnant women without evidence of immunity
Prevention Vaccine
Transmission: Varicella-zoster virus is transmitted from person to person by direct contact, inhalation of aerosols from vesicular fluid of skin lesions of varicella or herpes zoster, or from infected respiratory tract secretions that might also be aerosolized. The varicella zoster virus enters the host through the upper respiratory tract or the conjunctiva. The period of communicability is estimated to begin 1–2 days before the onset of rash and ends when all lesions are crusted, typically 4–7 days after onset of rash in immunocompetent people, but this period may be longer in immunocompromised people. People with varicella should be isolated for as long as lesions persist. In utero infection can also occur as a result of transplacental passage of virus during maternal varicella infection.
Symptoms: Varicella-zoster virus is transmitted from person to person by direct contact, inhalation of aerosols from vesicular fluid of skin lesions of varicella or herpes zoster, or from infected respiratory tract secretions that might also be aerosolized. The varicella zoster virus enters the host through the upper respiratory tract or the conjunctiva. The period of communicability is estimated to begin 1–2 days before the onset of rash and ends when all lesions are crusted, typically 4–7 days after onset of rash in immunocompetent people, but this period may be longer in immunocompromised people. People with varicella should be isolated for as long as lesions persist. In utero infection can also occur as a result of transplacental passage of virus during maternal varicella infection.
Treatment: Treatment with antivirals is not routinely recommended for otherwise healthy children with varicella. Treatment with oral acyclovir should be considered for people at increased risk for moderate to severe disease, such as people aged >12 years, people with chronic cutaneous or pulmonary disorders, people who are receiving long-term salicylate therapy, and people who are receiving short, intermittent, or aerosolized courses of corticosteroids. Intravenous acyclovir is recommended for immunocompromised people, including patients being treated with chronic (or high-dose) corticosteroids, and people with serious, virally mediated complications (such as pneumonia). Therapy initiated within 24 hours of onset maximizes efficacy. POSTEXPOSURE PROPHYLAXIS Vaccine Varicella vaccine is recommended for postexposure administration for unvaccinated healthy people aged ≥12 months and without other evidence of immunity, to prevent or modify the disease. The vaccine should be administered as soon as possible within 5 days after exposure to rash, if there are no contraindications to use. Among children, protective efficacy was reported as ≥90% when vaccination occurred within 3 days of exposure. No data are available regarding a potential benefit of administering a second dose to 1-dose vaccine recipients after exposure. However, administration of the second dose should be considered for these people to bring them up-to-date on vaccination. Varicella Zoster Immune Globulin People without evidence of immunity who have contraindications for vaccination and who are at risk for severe varicella and complications are recommended to receive postexposure prophylaxis with varicella zoster immune globulin (VZIG). People at high risk for severe complications include immunocompromised people, pregnant women without evidence of immunity, and some infants. The VZIG product used in the United States is available under an investigational new drug protocol and can be obtained from the sole authorized US distributor, FFF Enterprises (Temecula, California) toll-free at 800-843-7477 or www.fffenterprises.com. VZIG provides maximum benefit when administered as soon as possible after exposure but may be effective if administered as late as 10 days after exposure. If VZIG is not available, CDC recommends that administration of intravenous immune globulin be considered as an alternative (also within 10 days of exposure). Although there are limited published data on the benefit of acyclovir as postexposure prophylaxis, if VZIG is not available some experts recommend prophylaxis with acyclovir (80 mg/kg/day, administered 4 times per day for 7 days; maximum dose, 800 mg, 4 times per day), beginning 7–10 days after exposure for people without evidence of immunity and with contraindications for varicella vaccination.
