Urban Medicine: Threats to Travelers to Cities in Low-Income Nations

Infectious Diseases

Morbidity from infectious diseases is common in international travelers, with up to 75% of travelers becoming ill during their time abroad; these illnesses are most often self-limited episodes of diarrhea or upper respiratory illness. Almost every infectious disease for which travelers are at risk is transmitted in the urban setting. Indeed, it is easier to list infectious diseases that are not transmitted in cities than those that are. Japanese encephalitis, and bartonellosis, are among those not commonly spread in cities; however, these diseases are infrequent in travelers regardless of destination. Yellow fever is not currently endemic in urban areas, but its urban vector, the Aedes aegypti mosquito, is now present in urban areas of the Americas, and there is concern that yellow fever could erupt in explosive outbreaks from urban transmission cycles.

The vast majority of infectious diseases, including all the more common ones that are transmitted to international travelers, including hepatitis A, tuberculosis, and traveler's diarrhea, are vigorously transmitted in urban regions. Urban malaria is widespread throughout Asia and Africa. Many diseases, including meningococcal meningitis, are particularly associated with crowded living conditions. Zoonotic cutaneous leishmaniasis is expanding into many urban areas, including several cities in Colombia and peri-urban foci in Venezuela. In Brazil the national average dengue incidence rate is 34.5 cases per 100,000 inhabitants; in cities in Brazil the incidence rate of dengue fever can be as high as 268 cases per 100,000 inhabitants. Dengue fever in tourists is well documented. These infectious diseases are discussed in detail elsewhere in this book.

Trauma

Motor vehicle crashes are the most common cause of death in non-elderly travelers to the developing world. Travelers between the ages of 15 and 44 years have a two- to three-fold higher rate of death in accidents as compared with the same age group in developed nations. Males are more likely to be involved in both fatal and nonfatal accidents. A study of 309 Canadians who died abroad showed that 25% of deaths were due to accidents; motor vehicle crashes formed the biggest subgroup within the accidental death category. Accidental injury was by far the most common cause of illness and death reported for 801 visitors to Jamaica's northern coast, causing 22.3% of illness and death. Furthermore, tourists may be more likely than indigenous populations to become involved in motor vehicle crashes. In a study of tourists to Bermuda, the rate of motorcycle injuries was found to be 5.7-fold higher among tourists than among the local population. A study at a regional hospital in Corfu, Greece, showed that among residents and Greek tourists, only 15% of accidents were due to motor vehicle crashes, but among foreign tourists, 40% of accidents were due to motor vehicle crashes.

The amount of trauma attributable to driving on the opposite side of the road relative to travelers' home nations is not known but may be significant. In a study of nonfatal motor vehicle crashes in Greece, travelers from left-side-driving countries were more likely to be injured than those from right-side-driving countries. In New Zealand, the failure to drive on the left was found to be a significant factor in nonfatal motor vehicle crashes.

Travel by motor vehicle is markedly more dangerous in the developing world as measured by every metric that has been employed. The number of deaths per one billion vehicle kilometers is 3.7 in Sweden, 7.6 in the United States, and 55.9 in Brazil. Many countries probably have higher rates still, but motor vehicle crash-related mortality statistics are not collected in much of the developing world. A study performed in Ghana demonstrated that reports on fewer than 10% of pedestrian injuries were collected and tallied. An estimated 1.24 million people die each year from traffic injuries, and 25 million are permanently disabled. As bad as these statistics are, they appear to be growing worse rapidly.

The pattern of road traffic fatalities differs between developed and developing countries. In the United States, over 60% of road crash fatalities occur among drivers; in the least motorized countries, fewer than 10% of road crash fatalities occur among drivers. Most road traffic injuries in developing countries occur in urban areas, where approximately 90% of road traffic fatalities occur among passengers, pedestrians, and cyclists. Urban pedestrians alone account for 55-70% of road traffic deaths. Among children under the age of 4 years and between 5 and 14 years, the rate of death from road traffic injuries in low-income countries is six times that found in high-income countries. Those who reside in these countries are often aware of these risks. In Lagos, Nigeria, buses are known as danfos , “flying coffins,” or molue , “moving morgues.” A regular commuter on Lagos buses said, “Many of us know most of the buses are death traps but since we can't afford the expensive taxi fares, we have no choice but to use the buses.”

A study performed in Accra, the capital of Ghana, investigated alcohol use among drivers. Of 722 drivers who were selected randomly, 21% had a blood alcohol concentration higher than 80 mg/dL, indicating impairment. This rate is significantly higher than the rates of impaired drivers in the developed world, which range from 0.4% in Denmark to 3.4% in France. Alarmingly, 3.7% of bus drivers and 8.0% of truck drivers in this Ghana study had blood alcohol concentrations of ≥80 mg/dL.

Compounding this situation, there are no formal emergency medical systems in most low-income countries. In Ghana, 70% of trauma patients travel to the hospital by taxi or bus, 22% travel by private vehicle, 5% are brought by the police, and 3% travel by ambulance. All the patients who arrived in ambulances were transfers from other hospitals; no trauma patients were brought to the hospital directly from the field by ambulance. The absence of emergency medical services in the field and limited care at medical facilities combine to yield a markedly elevated rate of death following trauma relative to the developed world. In a study by , the mortality rate for patients with mid-level injury severity scores, which can be thought of as life-threatening but eminently treatable, was 6% at a level I trauma center in Seattle and 36% in Ghana—a six-fold difference.

Travelers should be advised to use seat belts whenever possible and to avoid riding in motor vehicles at night. Travel by motorcycle is less safe than travel by cars; travelers should avoid riding on motorcycles. Travelers should avoid riding in informal locations on vehicles, such as the roof of a bus or the back of an open truck. Travelers planning to rent bicycles, mopeds, or motorcycles should pack and wear appropriate helmets. Pedestrians should remain vigilant in urban settings and never assume they have the right of way. Additionally, pedestrians should not wear headphones or ear buds in urban settings.

Pre-travel providers should feel free to attempt to rearrange travelers' priorities. When travelers state that their top priority is addressing a particular (often uncommon) infectious disease, the pre-travel provider can reply, “Good question, we'll get to that; first let's discuss seat belts, helmets, and the benefits of assigning a designated driver.” Additionally, the benefits of obtaining medical and evacuation insurance prior to international travel should be discussed with every traveler. The information that emergency medical evacuation alone may cost US$50,000-100,000 may motivate travelers to obtain medical and evacuation insurance prior to travel.