Respiratory infection is a leading cause of seeking medical care in returning travelers. Respiratory infections occur in up to 20% of all travelers, which is almost as common as travelers’ diarrhea. Upper respiratory infection is more common than lower respiratory infection. In general, the types of respiratory infections that affect travelers are similar to those in nontravelers, and exotic causes are rare. Clinicians must inquire about history of travel when evaluating a patient for respiratory infections.
Viral pathogens are the most common cause of respiratory infection in travelers; causative agents include rhinoviruses, respiratory syncytial virus, influenza virus, parainfluenza virus, human metapneumovirus, measles, mumps, adenovirus, and coronaviruses. Clinicians also need to consider novel viral causes of respiratory infection in travelers, including Middle East respiratory syndrome (MERS) coronavirus and highly pathogenic avian influenza viruses. Respiratory infection due to viral pathogens may predispose to bacterial sinusitis, bronchitis, or pneumonia. Bacterial pathogens are less common but can include Streptococcus pneumoniae, Mycoplasma pneumoniae, Haemophilus influenzae , and Chlamydophila pneumoniae. Coxiella burnetii and Legionella pneumophila can also cause outbreaks and sporadic cases of respiratory illness.
Risk for Travelers
Reported outbreaks are usually associated with common exposure in hotels and cruise ships or among tour groups. A few pathogens have been associated with outbreaks in travelers, including influenza virus, L. pneumophila , and Histoplasma capsulatum . The peak influenza season in the temperate Northern Hemisphere is December through February. In the temperate Southern Hemisphere, the peak influenza season is June through August. Travelers to tropical zones are at risk all year. Exposure to an infected person from another hemisphere, such as on a cruise ship or package tour, can lead to an outbreak of influenza at any time or place.
Air-pressure changes during ascent and descent of aircraft can facilitate the development of sinusitis and otitis media. Direct airborne transmission aboard commercial aircraft is unusual because recirculated air passes through a series of filters, and cabin air generally circulates in limited areas within the aircraft. Despite this, influenza, tuberculosis, measles, and other diseases have resulted from transmission in aircraft. Transmission may occur via several pathways, including direct physical contact, fomites, direct droplet spread, and suspended small particles. Intermingling of large numbers of people in locations such as airports, cruise ships, and hotels can also facilitate transmission of respiratory pathogens.
The air quality at many travel destinations may be poor, and exposure to sulfur dioxide, nitrogen dioxide, carbon monoxide, ozone, and particulate matter is associated with a number of health risks, including respiratory tract inflammation, exacerbations of asthma and chronic obstructive pulmonary disease (COPD), impaired lung function, bronchitis, and pneumonia. Certain travelers have a higher risk for respiratory tract infection, including children, the elderly, and people with comorbid pulmonary conditions such as asthma and COPD.
The risk for tuberculosis among most travelers is low (see Chapter 3, Tuberculosis).
Identifying a specific etiologic agent, especially in the absence of pneumonia or serious disease, is not always clinically necessary. If indicated, the following methods of diagnosis can be used:
- Molecular methods are available to detect a number of respiratory viruses, including influenza virus, parainfluenza virus, adenovirus, human metapneumovirus, and respiratory syncytial virus, and for certain nonviral pathogens.
- Rapid tests are also available to detect some pathogens such as respiratory syncytial virus, influenza virus, L. pneumophila , and group A Streptococcus .
- Microbiologic culturing of sputum and blood, although insensitive, can help identify a causative respiratory pathogen.
- Special consideration should be given to diagnosing patients with suspected MERS (www.cdc.gov/coronavirus/mers/interim-guidance.html) or highly pathogenic avian influenza (www.cdc.gov/flu/avianflu/severe-potential.htm)
Most respiratory tract infections, especially those of the upper respiratory tract, are mild and not incapacitating. Upper respiratory tract infections often cause rhinorrhea or pharyngitis. Lower respiratory tract infections, particularly pneumonia, can be more severe. Lower respiratory tract infections are more likely than upper respiratory tract infections to cause fever, dyspnea, or chest pain. Cough is often present in either upper or lower tract infections. People with influenza commonly have acute onset of fever, myalgia, headache, and cough. At present, MERS should be considered in travelers who develop fever and pneumonia within 14 days after traveling from countries in or near the Arabian Peninsula. Certain other patients with illness following contact with a confirmed or suspected MERS case, or with health care facilities with MERS transmission, should also be evaluated.
Practitioners should be aware that regions associated with MERS may expand or change (www.cdc.gov/coronavirus/mers). H5N1 and H7N9 should be considered in patients with new-onset severe acute respiratory illness requiring hospitalization when no alternative etiology has been identified and if the patient has recently (within 10 days) been to a country with recently confirmed human or animal cases of H5N1 (www.cdc.gov/flu/avianflu/h5n1/case-definitions.htm) or H7N9 (www.cdc.gov/flu/avianflu/h7n9/case-definitions.htm) or has had close contact with an ill person who has traveled to these areas in the last 10 days. It should also be noted that highly pathogenic avian influenza A H5 virus has now been reported in wild birds and domestic poultry in the United States. Pulmonary embolism should be considered in the differential diagnosis of travelers who present with dyspnea, cough, or pleurisy and fever, especially those who have recently been on long car or plane rides.
Affected travelers are usually managed similarly to nontravelers, although travelers with progressive or severe illness should be evaluated for illnesses specific to their travel destinations and exposure history. Most respiratory infections are due to viruses, are mild, and do not require specific treatment or antibiotics. Self-treatment with antibiotics during travel can be considered for higher-risk travelers who develop symptoms of lower respiratory tract infections, such as those who have chronic bronchitis and who have been instructed by their providers to take an antibiotic for exacerbations. A respiratory-spectrum fluoroquinolone such as levofloxacin or a macrolide such as azithromycin may be prescribed to the traveler for this purpose before travel.
The rate of influenza among travelers is not known. The difficulty in self-diagnosing influenza makes it problematic to decide whether to prescribe travelers a neuraminidase inhibitor for self-treatment. This practice should probably be limited to travelers with a specific underlying condition that may predispose them to severe influenza.
Specific situations that may require medical intervention include the following:
- Pharyngitis without rhinorrhea, cough, or other symptoms that may indicate infection with group A Streptococcus .
- Sudden onset of cough, chest pain, and fever that may indicate pneumonia (or pulmonary embolism), resulting in a situation where the traveler may be sick enough to seek medical care right away.
- Travelers with underlying medical conditions, such as asthma, pulmonary disease, or heart disease, who may need to seek medical care earlier than otherwise healthy travelers.
Vaccines are available to prevent a number of respiratory diseases, including influenza, S. pneumoniae infection, H. influenzae type B infection (in young children), pertussis, diphtheria, varicella, and measles. Unless contraindicated, travelers should be vaccinated against influenza and be up-to-date on other routine immunizations. Preventing respiratory illness while traveling may not be possible, but common-sense preventive measures include the following:
- Minimizing close contact with people who are coughing and sneezing.
- Frequent handwashing, either with soap and water or alcohol-based hand sanitizers (containing ≥60% alcohol) when soap and water are not available.
- Using a vasoconstricting nasal spray immediately before air travel, if the traveler has a preexisting eustachian tube dysfunction, may help lessen the likelihood of otitis or barotrauma.
Appropriate infection control measures should be used while managing any patient with a respiratory infection (www.cdc.gov/flu/professionals/infectioncontrol).
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Regina C. LaRocque, Edward T. Ryan