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Epidemiology
: > 2,000 years ago, a plague gripped the Greek city of Athens. Ultimately,
as much as a third of the population succumbed and the devastation, which
helped Sparta gain the upper hand in the nearly 30-year-long war between
the city-states. That much Thucydides--an ancient historian, general in
the war and plague victim who recovered--conveys in his History of the
Peloponnesian War. But he did not leave a precise enough description
to decide definitively whether the disease was bubonic plague, smallpox
or a host of other ailments. Now DNA collected from teeth in an ancient
burial pit points to typhoid fever. In 1994 researchers discovered a mass
grave containing at least 150 bodies, including those of infants, deep
beneath the Kerameikos cemetery in Athens. Contrary to Greek custom, the
arrangement of the interred bodies grew progressively more haphazard as
they were piled on top of one another and few burial offerings, which included
a small number of vases, were left with the hastily buried corpses. Scientists
dated the vases to roughly 430 B.C., which is coincident with Thucydides'
report of when the plague broke out in the city. 3 random teeth samples
were picked from the plague victims and extracted the dental pulp. This
soft core under the hard tooth covering can store pathogens and other information
about the body for centuries. The researchers also tested 2 modern teeth
to make sure that no false results were indicated. Proceeding randomly
through a list of possible causes, Papagrigorakis' team tested the pulp
for the bacteria responsible for the bubonic plague, typhus, anthrax, tuberculosis,
cowpox and catscratch disease before finding a match in Salmonella
enterica serovar Typhi
--the
bacteria responsible for typhoid fever.
Typhoid fever--transmitted by contaminated food or water--causes fever,
rash and diarrhea, all closely matching Thucydides' account of the terrible
plague. The only thing that does not match up is the quick onset of the
disease, because modern cases of typhoid fever typically take longer to
gestate. This inconsistency may be explained by a possible evolution of
typhoid fever over time. Considering the overcrowding and unsanitary conditions
especially regarding the water supply within the walls of the besieged
Athens, a typhoid epidemic would have been likely to break outref.
In the 14th century plague killed one third of Europe's population
: around 1348, the population of England was estimated to be about 4 million,
and within 2.5 years about 1/3 had died from plague, sometimes called The
Great Dying. One third of the residents of Florence died in the first 6
months of the epidemic and as much as 75 percent died in a single year.
Venice lost 60 percent of its population over 18 months that the epidemic
raged. The last pandemics started in 19th century in China and
killed 12 millions people. Plague is still present in ... :
- Africa (where some people live in rat-infested villages, the death toll is the highest in the world) : Uganda and the Democratic Republic of the Congo. Pneumonic plague affected 130 suspect cases, including 57 deaths, in Zobia (a town that was home to at least 7000 diamond miners, some 300 km (186 miles) north of the provincial capital Kisangani), Bas-Uele district, Oriental province in eastern Congo, since 15 Dec 2004 to Mar 2005. The disease might have spread when 4000 of the miners left Zobia and disappeared into the bush 2 weeks ago, fleeing the disease and clashes involving various factions of the security forces guarding the mining arearef. As of 19 Jun 2006, WHO has received reports of 144 cases of suspected pneumonic plague, including 22 deaths in Ituri district, Oriental province. Suspected cases of bubonic plague have also been reported, but the total number is not known at this time. Ituri is known to be the most active focus of human plague worldwide, reporting around 1000 cases a year. The 1st cases in this outbreak occurred in a rural area, in the Zone de Sante of Linga, in mid-May 2006. There are now 12 zones in Ituri -- with total population of almost 100 000 -- affected by the plague outbreak. Bubonic plague, a less contagious form of the disease, is endemic to Ituri.ref1, ref2, ref3.
-
Asia : carriers of plague in central Asia are often Camelidae
getting their feet stuck in gerbil burrows, picking up the disease and
passing it on to their owners
- endemic in Mongolia
- the last case of plague was registered in Russia in 1979
-
Kazakhstan was the only former Soviet republic reporting plague : this
is, in part, because the Soviet Union actively suppressed all reports of
plague outbreaks. In fact, in 1949-50, there was a sizeable outbreak of
pneumonic plague, which may have killed upwards of 100 people, according
to Dr. Lev A. Melnikov, who was an eyewitness. Melnikov attributed the
outbreak to the dangerous plague reservoir Rhombomys
optimus
(the great gerbil). The first reports were from 1989. In the 1989-1997
period, 11 cases with 4 deaths were reported from the Guriev and Kzyl-Orda
regionsref
- Turkmenistan : an epidemic of plague began in May 2004 : > 20 deaths (7 in Mari, Ashgabad ) after 25 years of absence
- rural Americas (< 1.4% of world cases annually) :
- North America : southwestern USA. The introduction of plague into the US via California in 1900Lipson LG, 303-310 led to the spread of the infection eastward across about halfway across the country, but it did not reach the east coast (there are about 10-15 cases each year in humans in the USA) : although endemic in rodent populations the western USA, plague is most commonly seen in 2 regions:
- firstly :
- northern New Mexico : there were no reported cases of human plague in the state in 2004. 1 case was reported in Torrance County in 2003 and 2 cases were reported in 2002 in Santa Fe County. The last plague fatality occurred in 1994 in a Rio Arriba County child. There have been cases of plague in animals reported in 2005 in Rio Arriba, Santa Fe, Taos, Los Alamos, Colfax and Bernalillo Counties : an adolescent from Santa Fe County was affected by bubonic plague in July 2005 (rock squirrels collected in the vicinity of the patient's home were heavily infested with fleas, and fleas were collected from burrows in the area).
- northern Arizona
- southern Colorado : 3 Coloradans contracted plague in 2004 and 1 person died. In 2005 there were also 3 human cases of plague. 43 positive cases of plague in animals have been documented in Colorado in 2006ref
- Utah
- Texas : the last recorded human case of plague was in 1993 in a Kent County resident : in 2004 it has been isolated near the Midland-Glasscock counties border in West Texas and in fleas from wild prairie dogs in Dallam County in the Texas Panhandle
- secondly, California, southern Oregon, and western Nevadaref
- South America :
- Peru : northern
- Bolivia : in the Department of La Paz
- Brazil : several areas in northeastern
- Ecuador : the Chimborazo Province since 1977ref. 200-350 cases per year were reported from 1961 to 1966. 2 outbreaks of pneumonic plague occurred in Guamote county/canton, Ecuador in 1998 (160 casesref1, ref2) and 2004. Plague has been reported in this general region since first reports of cases in Chimborazo in 1977. There was a major outbreak in 1998 (approximately 160 cases) and 14 cases reported in 1999ref
The FBI and CDC are investigating the disappearance from a New Jersey research lab of at least 3 mice carrying a deadly strain of plague. The rodents have been missing for 2 weeks. Sources say FBI agents and bioterrorism experts are interviewing and polygraphing employees at the University of Medicine and Dentistry in Newark, N.J., the location of the lab run by the Public Health Research Institute, a leading center for research on infectious diseases. There are no indications of terrorism. The FBI responded to the matter, and we dedicated a great number of agents as well as a large number of resources to the investigation, which is still ongoing : we're satisfied that there is no public safety risk and there doesn't seem to be any nexus to criminal activity or terrorism. New Jersey officials also are downplaying the health risk. They believe the infected mice probably died quickly. However, some government officials are deeply concerned about what the case says about security of some of the most deadly infectious disease projects and research labs. One source admitted that while officials are saying there is minimal health risk, no one can be entirely certain. There is minimal information provided, but "3 mice" possibly represents only a single box of such animals in a BSL-3 facility. Occam's razor would indicate a stupid mistake, but as the loss was noted 2 weeks ago, all probable explanations will have been investigated and the answer is still being sought. If the mice had died, been incinerated, and the box emptied, cleaned, and sterilized, all traces will have been lost, along with any memories of what had happened. But the card for the box should have been kept along with any comments. If this were a break-in by Friends of the Earth, there would have been ancillary damage unless this has been suppressed. They have the experience to carry out such a "raid" -- if raid it was. Clearly those involved are assuming that the mice have died, if they were removed. Odd, but those with experience of such facilities probably have plenty of pre-Homeland Security war stories.
3 mice infected with the bacteria that cause bubonic plague have gone missing from a laboratory in Newark, New Jersey. Authorities have launched a search for the animals and an investigation into how they might have escaped. But researchers are quick to add that the mice, even if they are on the loose, pose little risk to the public. At this point we are satisfied that there is no public-safety risk, but the investigation is ongoing. The mice, which carried Yersinia pestis, were being studied at the Public Health Research Institute as part of a vaccine experiment. The institute, which handles about 10,000 mice a year, had a total of 24 plague mice in this experiment. Eight of these had not been vaccinated, 8 had been given the best current vaccine, and 8 had an experimental version: each group is missing a mouse, and has been for the past two-and-a-half weeks. There are many potential explanations. The rodents could have been stolen or accidentally incinerated along with bedding from the cages. It is even possible that they ate each other, as mice are known to do this when they have plague. The institute's director, David Perlin, acknowledges the possibility of theft, but says he thinks it is more likely to be an honest mistake. Some estimate that research into plague and plague vaccines has tripled in the United States following fears of bioterrorism sparked by the 11 September 2001 attacks. This trend means there are more infected animals scattered about the country that could, potentially, go missing. But experts have expressed surprise that such mice could actually escape. Research on plague takes place under tight security, in labs categorized as BSL3 and the entire lab is under video surveillance. The CDC is working with the FBI and local officials to see what happened. If the mice did actually escape from the lab, they would have quickly died from the disease. And the animals' bodies wouldn't be expected to pose a risk after decomposing for several days. Having plague running wild is not as unusual as some might think
A Los Angeles woman is being treated for bubonic plague, the 1st case of the age-old pestilence in the county since 1984, health officials announced Tue 18 Apr 2006. She may have contracted the disease from fleas in the area around her Country Club Park neighborhood. Although human cases of the plague are uncommon, it is endemic to ground squirrels and some rodents in parts of the Angeles National Forest, Tehachapi, Lake Isabella and Frazier Park.ref
Ring around the rosies,
A pocket full of posies,
Ashes, ashes!
We all fall down
Rosies represent rosary beads, used to (hopefully) provide divine intervention
against the disease. Plague victims may emit a rather strong and objectionable
odor; flowers (posies) could be carried to mask the smell. Ashes
are all that was left of a burnt corpse (in the Middle Ages). "All fall
down" reflects the profound death rate. Alternatively, for the last 2 lines
of the rhyme: The 3rd line can be replaced with "A Tishoo, a tishoo," which
represents the sneezes of the victims of pneumonic plague which are infectious
to others. To be sneezed on by them was a sure death sentence for all.
The death rate for those who acquire pneumonic plague directly is almost
100%.
Genomics : as many
as 13% of Y. pseudotuberculosis
genes no longer function in Y. pestis. The number of insertion sequence
(IS) elements (DNA sequences capable of interfering with gene expression)
has dramatically expanded in Y. pestis, delineating the probable
role of IS expansion in the elimination and modification of preexisting
gene expression pathways
Proteomics :
- 3 biovars :
- antiqua
- orientalis
- medievalis
- microcapsule, no flagella.
- PLD is required for survival in the midgut of rat flea.
- > 19 different antigenic components. Virulence factors (all plasmid-encoded) :
- fraction 1 (F1) capsular antigen is the principal antigen involved with both virulence and immunity. Although some experts consider a titer of antibody to F1 (determined by PHA) of at least 1:32 to be indicative of protection, the U.S. ACIP states that the minimum titer of antibody to F1 capsular antigen (determined by PHA) indicative of adequate protection against plague infection is 1:128 in animals.
- V antigen
- W antigen
- exotoxin
- endotoxin
- pesticin
- protease
- coagulase
- fibrinolysin
