"We're out of options." Drug Resistant Typhoid April 14, 2013
The
first known epidemic of extensively drug-resistant typhoid is spreading
through Pakistan, infecting at least 850 people in 14 districts since
2016, according to the National Institute of Health Islamabad.The
typhoid strain, resistant to five types of antibiotics, is expected to
disseminate globally, replacing weaker strains where they are endemic.
Experts have identified only one remaining oral antibiotic —
azithromycin — to combat it; one more genetic mutation could make
typhoid untreatable in some areas. Researchers consider the epidemic an international http://mbio.asm.org/content/9/2/e00482-18.full" rel="nofollow - clarion call
for comprehensive prevention efforts. If vaccination campaigns and
modern sanitation systems don’t outpace the pathogen, they anticipate a
return to the pre-antibiotic era when mortality rates soared. “This
isn’t just about typhoid,” said Dr. Rumina Hasan, a pathology professor
at the Aga Khan University in Pakistan. “Antibiotic resistance is a
threat to all of modern medicine — and the scary part is, we’re out of
options.”
Typhoid fever, caused by the Salmonella Typhi bacteria, is a highly infectious disease transmitted by contaminated food or water. It causes high fevers, headaches and vomiting. About 21 million people suffer from
typhoid each year, and about 161,000 die, according to the World Health
Organization.
Typhoid
is endemic to Pakistan, where poor infrastructure, low vaccination
rates and overpopulated city dwellings persist. Doctors in the Sindh
province were not surprised by an outbreak in November 2016 — until
cases proved unresponsive to ceftriaxone, used to treat
multidrug-resistant, or MDR, strains of typhoid.Only
four isolated cases of extensively drug-resistant, or XDR, typhoid had
previously been reported worldwide, according to Dr. Elizabeth Klemm, an
infectious disease geneticist at the Wellcome Sanger Institute in
England. The
outbreak’s origins were clear: Early case mapping revealed large
clusters of victims around sewage lines in the city of Hyderabad. Dr.
Hasan’s colleagues visited the region and found water sources that could
be contaminated by leaking sewage pipes. Four
deaths have been reported so far, according to the National Institute
of Health Islamabad. At least one travel-related case has been detected
in the United Kingdom. Genetic sequencing http://mbio.asm.org/content/9/1/e00105-18" rel="nofollow - revealed
that a common, aggressive MDR typhoid strain called H58 interacted with
another bacteria, likely E. coli, and acquired from it an additional
DNA molecule, called a plasmid, that coded for resistance to ceftriaxone.
The
findings were disturbingly simple: XDR strains can materialize in one
single step, virtually anywhere where the H58 strain and the added
plasmid are both present — whether a sewer system or even a single human
gut.“There
are multiple worst-case scenarios,” said Dr. Klemm. “One is that this
strain spreads to other regions through migration. But the other is that
it pops up elsewhere on its own — plasmids with drug resistance are
everywhere.”
But
the accumulation of resistance genes in the Sindh strain was hardly an
ambush, according to a commentary by vaccine experts at the University
of Maryland School of Medicine.
The
1948 discovery of antibiotic treatment for typhoid plunged the
infection’s fatality rate from almost one in four to just one in 100,
triggering “an epic thrust-and-parry duel” between powerful drugs and “a
wily bacterial foe’s stepwise acquisition of resistance to them,” wrote
Dr. Myron M. Levine and Dr. Raphael Simon.Doctors
still prescribe an estimated 50 million doses of antibiotics for
typhoid globally each year. In Karachi, the capital of Sindh province,
antibiotic resistance is increasing by 30 percent each year, according
to the W.H.O.; at that rate, all typhoid cases in the city will be
resistant to multiple drugs by 2020. Physicians
are treating the Sindh strain with azithromycin and other more
expensive treatments that must be administered in hospital settings. “Once
we aren’t able to treat this effectively, we’re going back to the
pre-antibiotic era. That would mean a lot of fatalities in our future,”
Dr. Klemm said. To
preserve the last line of defense, public health officials have
launched a campaign to vaccinate 250,000 children in Hyderabad using a
new typhoid conjugate vaccine, Typbar-TCV, recently prequalified by the
W.H.O. The vaccine lasts at least five years and can be given to
children as young as six months old, according to the W.H.O. Experts
are also reinforcing hygiene habits for prevention: washing hands
frequently, boiling drinking water and eating well-cooked foods. In the
longer term, modern sanitation infrastructure is needed. The
vaccination campaign has faced local opposition, according to local
news reports, amid rumors that the vaccines have been poisoned in a
Western effort to harm children. Similar suspicions https://www.nytimes.com/2015/02/15/world/asia/attack-on-polio-vaccination-team-in-pakistan-leaves-one-dead.html" rel="nofollow - have persisted
since 2011, when a posed hepatitis B campaign helped gather
intelligence before the Abbottabad raid that killed Osama bin Laden. Two
polio vaccination workers https://www.nytimes.com/2018/01/22/health/polio-pakistan-killing.html" rel="nofollow - were killed in Pakistan this January. GAVI,
The Vaccine Alliance, a public–private global health partnership
working to increase access to immunization, has pledged $85 million to
ensure that typhoid vaccines reach developing countries. “It’s
a global concern at this point,” said Dr. Eric Mintz, an epidemiologist
at the Centers for Disease Control and Prevention. “Everything suggests
this strain will survive well and spread easily — and acquiring
resistance to azithromycin is only a matter of time."
Source: https://www.nytimes.com/2018/04/13/health/drug-resistant-typhoid-epidemic.html" rel="nofollow - https://www.nytimes.com/2018/04/13/health/drug-resistant-typhoid-epidemic.html
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