Abstract
Visiting friends and relatives (VFRs) tend to have a higher prevalence of travel-related infectious diseases than other tourists. In addition, health care workers face special concerns when working abroad. Many illnesses, mostly infectious in origin, are associated with travel but can often be prevented. It is crucial to inquire about the countries traveled to, time of travel, travel activities, and basic health status to determine what illnesses need to be considered in a returning traveler who is sick. There are many websites that provide accurate, current information about travel-related health risks.
Keywords
cholera, malaria, rabies, travelers’ diarrhea
1
What are VFRs, and why is this population at particular risk of acquiring travel-related illness?
VFRs (visiting friends and relatives) are individuals who travel to visit relatives or friends, which often involves return to the individuals’ country of origin. VFRs tend to have a higher prevalence of travel-related infectious diseases (e.g., VFRs are eight times more likely to be diagnosed with malaria than are tourist travelers). Many VFRs assume immunity against infectious diseases in their home countries; however, immunity has often waned by the time of travel. Also, ≤30% of VFRs have a pretravel health care encounter, so these travelers may lack awareness of risk. Furthermore, many may travel to higher risk destinations while staying in homes that lack health amenities frequently available to foreign tourists, such as bed nets and safe food and water.
2
In a returning traveler who is sick, what illnesses might you suspect based on duration of time since travel?
Time since potential exposure can help identify illness in returning travelers. Chikungunya, dengue, Japanese encephalitis, enteric fever, influenza, and spotted fever Rickettsial illnesses often have an incubation period of <2 weeks. Hepatitis A and E often have an incubation of 2 to 6 weeks; enteric fever may also be seen during this time period. Hepatitis B, amebic liver abscesses, schistosomiasis, leishmaniasis, and tuberculosis often have an incubation of >6 weeks. Although malaria typically presents within 2 weeks of travel, symptoms may not develop for up to months after return (98% of Plasmodium falciparum infections present within 3 months of travel; however, almost 50% of P. vivax infections present after 30 days of travel and may not be seen until 12 months after return). Human immunodeficiency virus (HIV) may present at any time.
3
What special concerns do health care workers face when practicing abroad?
Health care workers who spend time abroad in health care settings may face health risks less prevalent in the United States, as well as decreased access to effective treatment while abroad. Risk is largely dependent upon the specific environment in which the health care worker operates. Specific considerations include increased exposure to bloodborne pathogens such as hepatitis B and HIV, highly contagious diseases such measles and tuberculosis, and epidemics such as cholera. Health care workers should consider bringing postexposure prophylaxis antiretrovirals with them for potential HIV exposure. Health care workers also may experience unique psychological stress related to their work.
4
What causes cholera and how is it treated?
The bacterium causing cholera, Vibrio cholerae, is typically acquired from untreated, contaminated water, but it can also be transmitted on food, especially seafood. The characteristic symptom is a diffuse, “rice-water” secretory diarrhea that may lead rapidly to hypovolemia. Treatment focuses on rehydration with oral rehydration solution and/or intravenous fluids; antibiotics, including macrolides, fluoroquinolones, or tetracyclines, may reduce symptom duration and fluid requirements but do not obviate the need for aggressive rehydration. In mid-2016, the FDA approved Vaxchora, a live, attenuated vaccine for the prevention of cholera caused by serogroup O1 in adults 18–64 years old.
5
What is the meningitis belt?
The meningitis belt is an area of sub-Saharan Africa where meningococcal meningitis is hyperendemic ( Fig. 56.1 ), most notably during the dry season (December–June). Although meningococcal outbreaks are most common in the meningitis belt, outbreaks can occur worldwide (notably, the Hajj pilgrimage to Saudi Arabia has been associated with outbreaks). Transmission occurs person-to-person by close contact with saliva or respiratory secretions. The six major Neisseria meningitidis serogroups are A, B, C, W, X, and Y; serogroup A predominates in the meningitis belt. At-risk travelers are recommended to receive a quadrivalent meningitis vaccine, which protects against serogroups A, C, W, and Y.
6
What causes travelers’ diarrhea, and how can it be prevented and treated?
Travelers’ diarrhea is the most common travel-related illness and occurs worldwide, especially in most of Asia, Mexico, Central and South America, Africa, and the Middle East. Bacterial pathogens are the typical cause, led by enterotoxigenic Escherichia coli . Prevention centers on good hand hygiene, avoiding ice and tap water in endemic areas, and eating foods that are well prepared. Oral hydration is key in treatment of travelers’ diarrhea. Indications for antibiotic use include more than four unformed stools daily, fever, or blood or mucus in the stool. In adults, a fluoroquinolone is often prescribed empirically; azithromycin is recommended for children, pregnant women, and travelers to Asia (where quinolone-resistant Campylobacter is prevalent).
7
What causes ciguatera, and what are the symptoms of ciguatera?
Reef fish (such as barracuda) predate on ciguatoxin-producing dinoflagellates. These fish may then accumulate the toxin and pass it to humans when eaten. Ciguatera typically presents with gastrointestinal symptoms starting 3–24 hours after eating a toxin-laden fish but may include more severe symptoms such as hypotension and bradycardia as well as neurologic and psychiatric symptoms such as paresthesias, hot/cold reversal, and hallucinations. Symptoms usually last a few days but may persist up to 4 weeks; treatment is primarily supportive. Ciguatera toxin–containing fish do not smell or appear unusual, and neither cooking nor freezing destroys the toxin. There is no clinical testing for ciguatera.
8
A patient presents to urgent care with facial flushing, diarrhea, and respiratory distress shortly after eating at a sushi restaurant. What likely caused this acute illness?
Scombroid, also known as histamine toxicity from fish, causes up to 40% of seafood-related, foodborne illness in the United States and is common worldwide. Illness occurs when bacteria, proliferating in poorly refrigerated fish, convert the amino acid histidine into histamine. Symptoms result from consuming histamine and present like an allergic reaction, starting between 5 and 60 minutes after eating contaminated fish. Classically, patients may describe contaminated fish as tasting bitter, peppery, or metallic, but concentrations of histamine needed to produce symptoms are much lower than concentrations needed to affect taste. Treatment is usually not necessary, although anti-histamines may be helpful and possibly epinephrine if anaphylaxis is a concern.
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