We don't know too much about a Nepalese man who's in medical
isolation in Texas while being treated for extensively drug-resistant
tuberculosis, or XDR-TB, the most difficult-to-treat kind. Health authorities
are keen to protect his privacy.
But we do know that he traveled through 13 countries — from
South Asia to somewhere in the Persian Gulf to Latin America — before he
entered the U.S. illegally from Mexico in late November. He traveled by plane,
bus, boat, car and on foot.
And all the way he may have unwittingly put hundreds of
other people at risk of getting the highly drug-resistant TB strain.
That possibility has triggered a far-reaching investigation
by the U.S. and other health authorities to track down potentially exposed
people around the world. "It's a huge effort that's ongoing," Dr.
Martin Cetron, who heads the division of global management and quarantine at
the Centers for Disease Control and Prevention, tells Shots.
The case, first described by Betsy McKay at the The Wall
Street Journal, provides a window on a problem that health officials say is
sure to arise more and more often.
XDR-TB is a more dangerous part of a bigger problem with
multi-drug-resistant tuberculosis, or MDR-TB.
"We estimate at any one time in the world there are
about 630,000 cases of MDR-TB," Dr. Dennis Falzon of the World Health
Organization tells Shots, referring to multi-drug-resistant TB. MDR-TB isn't
vanquished by the two mainstay drugs isoniazid and rifampin and requires more
complicated drug regimens.
In 2007, a young lawyer named Andrew Speaker became the
best-known case of MDR-TB when he flew to Europe, potentially exposing other
passengers.
XDR-TB is resistant not only to isoniazid and rifampin but
also a class of drugs called fluoroquinolones and one or more potent injectable
antibiotics. TB germs become drug-resistant when patients fail to complete a
course of treatment. When a partly-resistant strain is treated with the wrong
drugs, it can become extensively resistant.
There are about 60,000 people with XDR-TB strains like the
Nepalese man who's in isolation, Falzon says.
That means there are other people with XDR-TB traveling the
world at any given time. Like the Nepalese man, until he got to the U.S.,
Falzon says, "many of these XDR cases aren't even diagnosed."
Shots - Health News
Quick TB Test Builds Up Arsenal Against Drug-Resistant
Bacteria
Shots - Health News
Old Drug Gets A Second Look For TB Fight
Shots - Health News
A Troubling Rise In Drug-Resistant Tuberculosis
To give some idea of the public health challenge, such cases
present, Dr. Kenneth Castro of the CDC's division of TB elimination tells Shots
that over 700 people were thought to be exposed to the Nepalese man while he
was in the custody of the U.S. Border Patrol.
"Out of those, 60 percent or so are back in their
country of citizenship which then leaves many others that are being sorted
through to determine if (their exposure) was real or not," Castro says.
But at least those potential contacts were known. Falzon
says it's almost impossible to trace people who may have had close contact with
the man during his complicated itinerary.
"We cannot trace down a bus tour which happened within,
let's say, the space of a few weeks," Falzon says. "And it's very difficult
to get details. The person (in detention) doesn't speak English."
The long-haul flight he took from a country on the Persian
Gulf to Brazil, which exposed fellow travelers sitting within a couple of rows
of his seat, occurred months ago. "We're trying to track down the exact
details of that flight and the persons who were exposed," the WHO official
says.
TB is spread through droplets in the air released by
coughing or sneezing. It requires close and prolonged exposure, so a shorter
flight, for instance, is not thought to pose a danger.
Castro says there's no reason to think XDR-TB is more
contagious than less-resistant or drug-susceptible strains. "The alarm
bells have to do with the consequences of the disease," he says — that is,
the two-year, toxic, costly drug regimen necessary to cure the infection.
One big advantage these days, Castro says, is a lab test
that can tell within two days whether a patient's sputum contains TB bacilli
with mutations that confer resistance to seven different drugs.
"This is a game-changer," Castro says. The TB
organism is notoriously slow-growing, so it used to take six weeks to culture
it in laboratory dishes and test its susceptibility to different drugs.
"The result is that some folks died before results of drug susceptibility
tests came back," he says.
The CDC has recorded 63 cases of XDR-TB from 1993 through
2011 (the most recent data available), more than half of them among
foreign-born people.
When illegal immigrants with drug-resistant TB are isolated
in ICE detention facilities, things get complicated. They cannot be deported
until they're no longer contagious, which can require months of complex
treatment. Otherwise, they'd pose a risk to fellow travelers.
But Dr. Edward Zuroweste of the nonprofit group Migrants
Clinicians Network says just because such patients are no longer contagious
doesn't mean they're cured. This requires at least two more years of treatment
— often back in a home country without specialists in treating drug-resistant
TB or access to the proper drugs.
Zuroweste's group has a contract with ICE to make sure
deportees have appropriate treatment. It checks up on them regularly to see if
they're sticking with it. He says 84 percent complete treatment, and the rest
either disappear or refuse further treatment.
He says the U.S. and other nations should expect to see
growing numbers of these difficult cases. "There's no way to ever isolate
the U.S. from an airborne disease," Zuroweste tells Shots. "The world
is becoming much smaller and people travel a lot. So what we have to do is
attack the disease, not the individual unfortunate enough to contract the
disease."
