H5N1 & Marburg outbreaks
From ANIMAL PEOPLE, April 2005:
HANOI, LUANDA–If an epidemiologist’s worst nightmare isn’t
the avian influenza strain called H5N1, it might be Marburg
hemorrhagic fever, a virulent close cousin to the better known Ebola
virus. Both are zoonotic diseases, meaning that they spread to
humans from animals. With a quirk or two of virus evolution, both
could depopulate continents. The worst-ever outbreaks of each are
raging right now in Southeast Asia and Central Africa.
H5N1, discovered after it killed three people in Hong Kong in 1997,
apparently crossed from migratory wild birds to ducks and geese
reared in huge outdoor pens and paddies in southern China, crossed
to indoor-raised chickens, then raced throughout Southeast Asia with
the mostly illegal but lightly prosecuted commerce in gamecocks.
Killing about 70% of the humans who contract it from birds,
H5N1 has not killed millions chiefly because it has not evolved into
a form that spreads easily from human to human, and does not spread
easily from bird to human. Only the estimated 25 to 40 million
Southeast Asians who raise poultry are believed to be at risk of
becoming infected by the bird-to-human route.
A 10-year-old girl who died on March 27, 2005 in Hanoi was
the 50th known human fatality since January 2004, and the 36th
Vietnamese. Twelve Thais have died, and two Cambodians. There
have been more than 3,000 known outbreaks among poultry. More than
60 million birds have either died from H5N1 or have been gassed,
buried alive, or even burned alive in mostly futile control efforts.
China introduced an H5N1 vaccine for poultry in December
2003, has since introduced two more of increasing efficacy, and has
innoculated more than 2.7 billion domestic fowl since January 2004.
Indonesia began vaccinating 50 million poultry in March 2005. There
are H5N1 vaccines for humans, too, but world production of all
human flu vaccines combined is only 500 million doses per year. Only
the U.S. is believed to have vaccination coverage enough to slow a
serious flu epidemic.
Marburg was first identified in 1967, after laboratory
workers in Marburg and Frankfort, Germany, and Belgrade,
Yugoslavia, received infected monkeys who were captured in Uganda.
Until 2005 the biggest known outbreak killed 123 people from 1998 to
2000 in the Democratic Republic of Congo. As with Ebola, the first
victims are typically young men who have eaten monkeys. They infect
their families, who infect health workers.
Like Ebola, Marburg is so infectious and kills so quickly
that it has so far always burned itself out before mutating into a
strain that victims could carry into contact with many others.
Ebola victims typically have contact with 12 other people before
death; Marburg victims have contact with just four.
The current outbreak hit Uige, Angola, 200 miles north of
Luanda, in October 2004. Government censorship suppressed awareness
of it until it reached the outskirts of Luanda, killing 29 people in
the first four days of April 2005. People believed to have had
exposure to victims were quarantined as far away as Italy and
Portugal. The known death toll by April 5 was 156, including more
than 125 children under age 15, with 88% mortality among identified
cases. While the initial source of the outbreak is unknown,
recycling the needles used to give childhood vaccinations is believed
to be the major cause of the unprecedentedly high mortality among