Among returning travelers, respiratory infections are a leading cause for seeking medical care. Upper respiratory infection is more common than lower respiratory infection. In general, the types of respiratory infections affecting travelers are similar to those in nontravelers, and exotic causes are rare. Clinicians should inquire about the details of travel (such as type of travel and travel destinations) when evaluating a returning traveler with a respiratory infection.
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. Consider also viruses of special concern in travelers, including Middle East respiratory syndrome (MERS) coronavirus and highly pathogenic avian influenza viruses. Include MERS in the differential diagnosis of travelers who develop fever and pneumonia within 14 days after traveling from countries in or near the Arabian Peninsula. Contact with a confirmed or suspected MERS case, or with health care facilities with MERS transmission, is of special concern, even in the absence of confirmed pneumonia. Be aware that regions associated with MERS may expand or change (see Chapter 4, Middle East Respiratory Syndrome, and www.cdc.gov/coronavirus/mers).
Consider a diagnosis of highly pathogenic avian influenza viruses (such as H5N1 and H7N9) in patients with new-onset severe acute respiratory illness requiring hospitalization when no alternative cause has been identified. A history of recent travel (within 10 days) to a country with confirmed human or animal cases—especially if the traveler had contact with poultry or sick or dead birds—improves the likelihood of the diagnosis (see Chapter 4, Influenza, and www.cdc.gov/flu/avianflu/specific-flu-viruses.htm).
Bacterial pathogens are less common than viral but can include Streptococcus pneumoniae, Mycoplasma pneumoniae, Haemophilus influenzae , and Chlamydophila pneumoniae. Coxiella burnetii and Legionella pneumophila can cause outbreaks and sporadic cases of respiratory illness. Bacterial sinusitis, bronchitis, or pneumonia may also occur secondarily after a viral respiratory infection.
Outbreaks may occur following common-source exposures in hotels, on 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, peak influenza season runs from June through August. There is no peak season for influenza in tropical climates; the risk of infection is present 12 months of the year. Exposure to an infected person traveling from another hemisphere, such as on a cruise ship or on a package tour, can lead to influenza outbreak 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 within limited zones or areas of 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 (see Chapter 3, Air Quality & Ionizing Radiation). Certain travelers have a higher risk for respiratory tract infection, including children, the elderly, and people with comorbid pulmonary conditions such as asthma or COPD.
Risk for tuberculosis among most travelers is low (see Chapter 4, Tuberculosis).
Most respiratory 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 respiratory tract infections. People with influenza commonly have acute onset of fever, myalgia, headache, and cough. Consider pulmonary embolism 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 (see Chapter 8, Deep Vein Thrombosis & Pulmonary Embolism).
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:
Travelers with respiratory infections 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. Travelers with pneumonia, as established by the presence of an infiltrate on chest radiography, can be treated with antibiotics in accordance with existing guidelines for community-acquired pneumonia. Antiviral treatment is recommended for travelers with influenza who have severe disease or who are at a higher risk for complications; it can be considered for others who present within 48 hours of symptom onset.
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:
Appropriate infection control measures should be used while managing any patient with a respiratory infection (www.cdc.gov/flu/professionals/infectioncontrol).
Regina C. LaRocque, Edward T. Ryan