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Arboviruses of Medical Importance

Abstract Arboviruses are transmitted to humans primarily through the bites of arthropod vectors such as mosquitoes, ticks, and sandflies. Half of the world’s population live in areas endemic for arboviruses, which cause significant morbidity and mortality in both developed and developing countries. More than 130 arboviruses are known to infect humans, but only a much smaller number are medically important. Since 2015, there have been major…

Rabies

Acknowledgment The author acknowledges the work of Kis Robertson, Nina Marano, and Katherine J. Johnson on this chapter in the previous edition. Abstract Rabies has been recognized as a source of great human suffering and fear since ancient times. Characterized by a near 100% case fatality rate, it is among the deadliest infectious diseases known to humanity. The rabies virus (RABV) is present in the saliva…

Hepatitis A, B, C, D, and E: Focus on Adult Infections

Acknowledgment The authors acknowledge the work of Michael James Babineaux and Miriam J. Alter on this chapter in the previous edition. Abstract Viral hepatitis is caused by infection with five distinctly different human viruses that cannot be distinguished from one another without serologic testing ( Table 68.1 ). Hepatitis A virus (HAV), hepatitis B virus (HBV), hepatitis C virus (HCV), hepatitis delta virus (HDV), and hepatitis…

Enteric Fever: Typhoid and Paratyphoid Fever

Abstract Infection with the gram-negative bacteria Salmonella enterica serotype Typhi ( S . Typhi) or S. enterica serotype Paratyphi A, B, or C ( S. Paratyphi A, B, or C) may result in a serious febrile illness known as enteric fever. The illness is called typhoid fever or paratyphoid fever once the causative agent has been identified. Pathogenic Salmonella bacteria causing invasive disease are a particular…

Cholera

Abstract Vibrio cholerae is a noninvasive small intestinal pathogen that produces cholera toxin, resulting in severe acute watery diarrhea in humans. Vibrio are gram-negative bacteria that live in marine and freshwater environments, and the O1 and O139 serogroups of V. cholerae can cause both endemic and epidemic cholera. Transmission occurs via the fecal-oral route, and humans lacking access to clean water are most likely to be…

Travelers’ Diarrhea

Abstract Acute diarrhea associated with travel is referred to as travelers’ diarrhea (TD) and is the most frequent illness among travelers. TD is defined as an acute illness associated with an increase in frequency and change in stool form (loose or liquid) compared with normal in an individual from one region who has traveled to another. It is frequently associated with other gastrointestinal symptoms that may…

Yellow Fever

Abstract Yellow fever (YF) is a vector-borne disease resulting from the transmission of the YF virus to a human from the bite of an infected mosquito. It is endemic to sub-Saharan Africa and tropical South America. Infection in humans can cause mild, undifferentiated febrile illness to severe disease with jaundice and hemorrhagic manifestations. All travelers to YF-endemic countries should be advised of the risks of acquiring…

Malaria

Abstract Malaria is a bloodborne protozoan parasite mostly transmitted from person to person by bites of infected female Anopheles mosquitoes in tropical and subtropical regions. Despite a substantial reduction in the malaria burden observed since 2010, largely attributed to effective control measures and treatment regimens, the World Health Organization (WHO) still reported 228 million infections and 405,000 deaths in 2018. The majority of deaths from malaria…

Introduction to Infections Associated With International Travel and Outdoor Activities

Abstract Travel in the broadest sense means going from one place to another, especially journeys to distant or unfamiliar places, and the theme of travel being associated with exposure to exotic infectious diseases (IDs) has been a recurring one throughout history. This section covers a variety of IDs that may be encountered during international travel and through participation in outdoor activities: these two kinds of exposures…

Bacterial Vaginosis, Related Syndromes, and Less Common Sexually Transmitted Diseases

Abstract Bacterial vaginosis (BV), the most common cause of vaginal discharge in the United States, is not traditionally described as a sexually transmitted infection (STI) but is well documented to be sexually associated. In the United States, two STIs—chancroid and granuloma inguinale—are uncommon diseases associated with genital ulcerations. These two infections may be encountered outside the United States and are significant risk factors for human immunodeficiency…

Syphilis (Treponema pallidum)

Abstract Syphilis is a complex systemic disease caused by the spirochete Treponema pallidum subspecies pallidum . Syphilis is transmitted sexually or congenitally and can involve nearly every organ system. Its clinical progression involves several well-characterized stages: (1) an incubation period of 1 week to 3 months; (2) a primary stage characterized by a chancre (an indurated, nontender ulcer at the site of exposure); (3) a secondary…

Infections With Neisseria gonorrhoeae

Abstract Diagnosis of infection with Neisseria gonorrhoeae (NG), commonly known as gonorrhea, is important because the sequelae of untreated gonorrhea can include pelvic inflammatory disease (PID), perihepatitis, ectopic pregnancy, infertility, and chronic pelvic pain in women and epididymitis or infertility in men. Infection with gonorrhea also increases risk of both acquiring and transmitting human immunodeficiency virus (HIV). Gonorrhea is the second most common notifiable condition in…

Infections Caused by Chlamydia trachomatis , Including Lymphogranuloma Venereum

Abstract Chlamydia trachomatis is an obligate intracellular bacterium that infects mucosal surfaces of humans, including oropharyngeal, anogenital, and conjunctival surfaces. C. trachomatis can be classified through molecular typing into strains causing ocular infections (trachoma), nonulcerative oropharyngeal and/or anogenital infections (chlamydia), and a distinct ulcerative syndrome called lymphogranuloma venereum (LGV). C. trachomatis infections are highly prevalent worldwide, especially in adolescents and young adults, and can cause substantial…

Human Papillomavirus

Abstract Genital human papillomavirus (HPV) infection is estimated to be the most common sexually transmitted infection (STI) in the United States and worldwide. Oncogenic, or “high-risk” HPV types, such as HPV types 16 and 18, can cause cervical and other anogenital precancers, anogenital cancers, and oropharyngeal cancers. Other HPV types, such as HPV types 6 and 11, can cause anogenital warts as well as recurrent respiratory…

Human Immunodeficiency Virus and Acquired Immunodeficiency Syndrome

Abstract Human immunodeficiency virus (HIV) is a sexually transmitted infection that causes progressive immune dysfunction, putting affected individuals at risk for opportunistic infections and certain cancers. It was first recognized in the early 1980s, when men who had sex with men (MSM) in several cities in the United States presented with an unusual fungal pneumonia caused by Pneumocystis carinii (now called Pneumocystis jiroveci ) and others…

Herpes Simplex Virus Genital Infection

Abstract Genital herpes is a globally endemic sexually transmitted infection (STI) and the most common cause of genital ulcer disease. Classically, genital herpes manifests as a cluster of painful vesicular or ulcerative mucocutaneous lesions; however, such presentations account for a minority of cases, as the clinical manifestations vary widely. Genital herpes is caused by herpes simplex virus type 1 (HSV-1) or type 2 (HSV-2), two closely…

Trichomonas vaginalis

Abstract Trichomonas vaginalis is estimated to be the most common treatable sexually transmitted infection (STI) worldwide. It is an important contributor to perinatal morbidity, cervical cancer, poor sperm quality, and HIV acquisition and transmission. Less is known about the importance of asymptomatic infection. T. vaginalis shares many of the same risk factors as other STIs but tends to be more prevalent among older women. Risk factors…

Surgical Site Infections

Abstract Surgical site infections (SSIs), previously known as wound infections , remain one of the most common adverse events that occur with hospitalized surgical patients or after outpatient surgical procedures, despite many advances in preventive techniques. A 2015 report from the National Healthcare Safety Network (NHSN) of the Centers for Disease Control and Prevention (CDC) documents SSI as accounting for 16% of all healthcare-associated infections (HAIs)…

Pyomyositis (Pyomyositis Tropicans)

Acknowledgments The authors would like to acknowledge Dr. Joseph F. Woodward for his contribution to this chapter in the previous edition. Abstract Pyomyositis, a disease historically seen in tropical climates, is characterized by primary abscess formation in the skeletal musculature. It is increasing in incidence in temperate climates, especially in immunocompromised hosts. In all cases, Staphylococcus aureus is the most commonly implicated organism. Clinical presentation is…