So, following on polio, a little more about diseases crossing borders.
As a kid, I went to a girls’ convent school outside London. (Blazer, boater, motto, crest. Elocution and deportment. Embroidery classes.) There were about three Americans that I remember, and a few South Asians living in the UK, and some girls whose parents were British but living abroad. One of the regular features of the return to term was an interrogation by the headmistress: Had anyone had any illness in their family over the holidays? One New Year, not knowing any better, I put up my hand. Why, yes, I said innocently; my brothers had had measles.
Fingers drummed. Jaws locked. I was whisked to the headmistress’s study. My mother was summoned. She protested that I had been vaccinated. The headmistress was unmoved. I was barred from school for the presumed incubation period. My mother was not pleased. (“You should have lied,” she hissed once we got home.)
It was my first introduction to the idea of contagion, and also to the practice of quarantine — the idea of confining someone who has been exposed to a disease in another place, and thus poses a potential risk to people in the place where she has arrived. (“Quarantine” is said to come from quarantina giorni, the “40 days” that ships had to sit at anchor outside ports in Italy in the 1600s to make sure any plague on board had burned itself out. Fortunately for me, I only had to wait a week.)
I often think about quarantine, not just because of my school experience but because I live in Minneapolis and Atlanta, whose airports house two of the 20 quarantine stations maintained at the US border by the Centers for Disease Control and Prevention. The “Q stations” are unobtrusively tucked into the no-man’s land between passport control and customs release, the territory patrolled by those focused and adorable USDA beagles that it is almost always a mistake to pet. If you weren’t looking for the Q stations — usually designated by a small, unremarkable sign and a door that locks — you would never notice them.
I wonder whether we shouldn’t make the signs bigger. We could use some reminders, right now, that it is likely that we will be exposed to diseases when we travel, and that we have a responsibility to prevent their spread.
In a new paper in the Journal of Travel Medicine, a group of researchers from the CDC, the Harvard School of Public Health and Massachusetts General Hospital underline how uncommon thinking about cross-border disease transmission has become. They surveyed 1,254 US residents who were leaving from Boston’s Logan Airport en route to developing countries, and found that 46 percent made no effort to seek out health advice before their trips.
“The most commonly cited reason for not pursuing health information was a lack of concern about health problems related to the trip,” they say.
The travelers were all permanent residents of the US, though some were foreign-born and headed to visit friends and relatives:
- 21% verified that their immunizations were up to date
- 36% obtained a prescription medication for travelers’ diarrhea
- 20% were carrying prescription antimalarial drugs.
Those are low percentages. Clearly, the travelers to low-income countries weren’t thinking about the diseases they might contract or bring back.
Why is this a bad idea? Because of the large numbers of US residents who do bring something back each year, imperiling themselves and sometimes others. There are more than 1,000 cases of malaria in US travelers each year, and they are usually traced to people failing to finish their course of malaria prophylaxis, or sometimes even to to start one. I’ve taken malaria prophylaxis and it’s no fun — basically, you have a choice between projectile vomiting and psychosis — but it’s worth it: Each year, several US residents die of a malaria infection they acquired abroad.
Perhaps that sounds like a low risk. Then consider this: More than 50 million people travel from the industrialized world to the developing world every year. More than half of them come back with something that makes them at least briefly sick. In 2006, a worldwide association of travel clinics in academic medical centers, called the GeoSentinel Surveillance Network, analyzed treatment records for 17,353 travelers who had gone to 230 countries, and found that 8 percent of them were sick enough to need medical care, and 10 percent of that 8 percent — roughly, 1 in 100 — had illnesses that lasted, and in some cases didn’t even manifest, for at least 6 months.
Among the illnesses people came back with: malaria, of course, but also dengue; several varieties of hepatitis; tick-borne illnesses; parasitic diarrhea; cholera; meningitis, and sexually transmitted diseases.
So, again, why care? These numbers are small. We care because, by the carelessness of bad planning combined with the bad luck of exposure, these travelers made themselves into potential vectors of infection for their families, their communities and their home countries. The conditions exist in the United States that will support the spread of hepatitis, malaria, dengue, and certainly STDs. All that is necessary is the organism.
How big an outbreak can an imported infection cause? Ask Canada. In the spring of 2003, a Chinese-Canadian family went back to Hong Kong for a visit. Around the time they left for home, the mother and one of her adult sons started feeling sick with what felt like the flu. She died of a heart attack at home in Toronto. A few days later, he went to a crowded local ER, where he lay on a gurney for 18 hours, awaiting care. He infected the man 5 feet to the right, who was in the ER for 9 hours before being sent home; and the man 15 feet to the left, who was admitted upstairs after only a few hours. All three of them died in the next three weeks, the first of 39 deaths and 438 cases that paralyzed Toronto during the international epidemic of SARS.
In 1977, the British virologist WIB Beveridge wrote — of flu, but it applies to all infectious diseases: “A spark in a remote corner of the world could become a fire that scorches us all.” It would be good not to be the spark, if we can.
UPDATE: A little while after I posted this, the ProMED list relayed a CDC report of two flight attendants and two pilots who all contracted falciparum malaria after a 2-3 day stay in Ghana. All four were hospitalized and both pilots were intubated. None of them took the prophylaxis offered by the airline. All four fortunately recovered.
Cite: LaRocque, RC et al. Pre-travel Health Advice-Seeking Behavior Among US International Travelers Departing From Boston Logan International Airport. Journal of Travel Medicine. dx.doi.org/10.1111/j.1708-8305.2010.00457.x