agent/disease |
animals provide early warning of acute bioterrorism attack because
an animal species had increased susceptibility to a particular agent, because
the disease caused by the agent had a shorter incubation period, or because
animals were exposed sooner (or at more intense and continuous levels)
than the human populationref
|
Animals could be markers for ongoing exposure risk if a released
biological agent persists in the environment (such as soil, water, or air).
Aside from case detection, active surveillance with surveys of animals
may be useful; this surveillance may require testing wildlife as well.
Such testing could involve antibody seroprevalence or use of polymerase
chain reaction techniques to detect antigen. Evidence about the usefulness
of such an approach was inconsistent.
|
Animals can propagate/maintain epidemic
|
Category A |
Bacillus anthracis |
Yes: sheep, cattle (level 3 evidenceref)
No: dogs and pigs (level 1 evidenceref)
whether animals would have a shorter incubation period in the event
of an aerosol release was not clear, since the incubation period in the
2001 mail attacks was <4 days, while during the 1979 release of B. anthracis
from a Soviet military laboratory, human symptoms began in 2 days, with
death in as few as 6 days. At the same time, while human cases in Sverdlovsk
were concentrated along the path of the prevailing wind <4 km from the
laboratory, livestock, including sheep and cows, began dying 3 days after
the release in 6 villages located along the path of the aerosol at a distance
<50 km downwind from the facility. No human cases were reported in these
villages. Calculations of the airborne B. anthracis dosage at a
town where several sheep and a cow died indicate that the animals were
exposed to a dose more than an order of magnitude lower than humans received
near the weapons facility. This finding suggests that sheep and cows are
more susceptible than humans, although they could have also remained outside
in the path of the aerosol for a longer period, which led to greater exposure |
Yes: sheep, cattle (level 3 evidenceref1,
ref2).
Although dogs and cats are less susceptible to B. anthracis than
ruminants, their proximity to humans and their contact with soil could
make them sentinels; for example, anthrax developed in a Labrador retriever
after the dog hunted in a freshly plowed fieldref |
- |
Yersinia pestis |
Yes: cats (level 1 evidenceref)
: evidence from experimental inhalation studies indicates that the usual
incubation period for symptoms of plague to develop after an inhalation
exposure may be shorter (1–2 days) than the presumed incubation time for
humans (1–6 days), which provides evidence that symptoms develop in cats
at the same time as in humans, and thus may have some sentinel value |
Yes: dogs, cats (level 1 evidenceref),
multiple species (level 2 evidenceref) |
Yes: cats, camels, goats (level 3 evidenceref1,
ref2) |
Francisella tularensis |
No (level 3 evidenceref)
: during a prolonged outbreak of pneumonic tularemia in Scandinavia, for
example, febrile illness developed in a number of horses, a cow, and a
pig, but apparently not before the onset of disease in humans living nearby |
Yes: rodents (level 2 evidenceref)
No: horses, cows (level 2 evidenceref)
During an epidemic of pneumonic tularemia, attributable to contaminated
hay, F. tularensis can persist in the environment; a serosurvey
of asymptomatic livestock (horses and cows) did not show evidence of exposureref.
By contrast, in a more recent tularemia outbreak, serosurveys in the wildlife
population did show antibodies in a skunk and a rat that lived near persons
who had become infected after mowing fieldsref |
Yes: ticks, rodents, prairie dogs (level 2 evidenceref) |
Clostridium botulinum |
No (level 3 evidenceref) |
No (level 3 evidenceref) |
No (level 3 evidenceref) |
Filovirus (Ebola
virus ,
Marburg
virus ) |
Studies in Africa have demonstrated that Ebola virus outbreaks can
be preceded by deaths in primates as well as in other animal species such
as duikers (type of antelope)ref,
but whether a generalized attack that used Ebola virus in the USA would
affect certain animal species first is unknown. |
- |
Yes: wildlife (level 3 evidenceref).
The results of animal surveillance for Ebola virus in Africa found that
ongoing outbreaks in both primates and duikers suggest that the virus may
be able to propagate in a wildlife population, however, this characteristic
has not been demonstrated in US wildlife species. |
Category B |
Coxiella burnetii |
No: sheep (level 1 evidenceref)
: infection in animals is either asymptomatic or develops so slowly
that recognizable human cases seem certain to precede animal cases if the
agents are released as an aerosol. |
Yes: wild hogs, goats (level 2 evidenceref1,
ref2) |
Yes: cats, sheep, goat, cattle (level 3 evidenceref) |
Brucella spp. |
No (level 3 evidenceref)
: infection in animals is either asymptomatic or develops so slowly
that recognizable human cases seem certain to precede animal cases if the
agents are released as an aerosol. |
Yes: cattle (level 2ref) |
Yes: wildlife, cattle, dogs (level 3 evidence (Radostits OMG, Gay CC,
Blood DC, Hinchcliff KW, editors. Veterinary medicine: a textbook of the
diseases of cattle, sheep, pigs, goats and horses. 9th ed. London: Harcourt
Publishers Ltd; 2000)) |
Foodborne illness: Salmonella
spp. ;
Shigella
spp. ;
Cryptosporidium
parvum ,
etc. |
Yes: cattle (level 3 evidenceref).
animals would likely not manifest illness before humans if an attack were
directed at humans, since in a typical attack scenario, food would be infected
during the distribution pathway before consumption by humans and not necessarily
allow for animal consumption before this. However, if the attack on the
food supply were directed at the animals themselves, they could potentially
manifest symptoms before humans who would consume the meat, eggs, or dairy
products. Attacks on water supplies with agents such as Clostridium
botulinum could put humans at risk as well, although dilution and water
treatment would reduce the riskref.
An exception may be Cryptosporidium spp., which have caused widespread
outbreaks through the water supply. Waterfowl die-offs from type C and
type E botulism have been well documented, although these types are not
well recognized as causes of clinical C. botulinum poisoning in
humans, but the fact that primates are susceptible to type C makes C.
botulinum poisoning a possibility. On the whole, however, an attack
on human populations with C. botulinum would probably not be first
detected in animals; the illness would have such a short incubation period
in humans that they would become symptomatic at the same time as or before
the animals |
- |
- |
Burkholderia mallei |
– |
Yes: horses (level 2 evidenceref) |
Yes: horses (level 3 evidence (Greene CE. Infectious diseases of the
dog and cat. 2nd ed. Philadelphia: W.B. Saunders; 1998)) |
Alphaviruses (Venezuelan
equine encephalitis virus (VEEV) ,
Eastern
equine encephalitis virus (EEEV) ,
Western
equine encephalitis virus (WEEV) ) |
Yes: horses (level 3 evidence (Greene CE. Infectious diseases of the
dog and cat. 2nd ed. Philadelphia: W.B. Saunders; 1998)) : natural outbreaks
have often appeared in animal populations before they affected humans,
for example, EEEV often appears in equines 2 weeks before humans become
symptomatic. Whether the same pattern would hold true during an attack
with an aerosol is not clear. |
Yes: birds (level 1 evidenceref) |
Yes: wild birds (level 2 evidenceref).
Agents such as alphaviruses that are prevalent in wild bird populations
can spread over a wide area in a short time |
Rift valley fever
virus |
Yes: cattle, sheep (level 3 evidence (Radostits OMG, Gay CC, Blood
DC, Hinchcliff KW, editors. Veterinary medicine: a textbook of the diseases
of cattle, sheep, pigs, goats and horses. 9th ed. London: Harcourt Publishers
Ltd; 2000)) : 12-hour incubation period compared to the incubation period
of several days in humans |
Yes: sheep (level 1 evidenceref) |
Yes: mosquitoes, rodents (level 1 evidenceref).
Studies of mosquitoes native to the USA have demonstrated their potential
to spread a disease such as Rift Valley fever through livestock and other
animal populations, even though person-to-person transmission does not
occur |
ricin |
- |
- |
- |
e toxin of Clostridium
perfringens |
- |
- |
- |
Category C (emerging diseases) |
Nipah virus |
- |
Yes: multiple species (level 3 evidence (Bunning M. Nipah virus outbreak
in Malaysia, 1998–1999. Journal of Swine Health Products. 2001;9:295–9)) |
Yes: pigs (level 1 evidenceref) |
Hantavirus |
No (level 2 evidenceref)
: infection in animals is either asymptomatic or develops so slowly
that recognizable human cases seem certain to precede animal cases if the
agents are released as an aerosol. |
Yes: multiple species (level 2 evidenceref) |
Yes: rodents (level 2 evidenceref
[33]) |
Flavivirus (WNV ,
JEV ) |
Yes: wild birds (level 3 evidenceref) |
Yes: mosquitoes, birds (level 2 evidenceref) |
Yes: birds (level 1 evidenceref).
WNV can easily spread from animal to animal in bird populations |
Level 1 evidence, experimental or cohort study or randomized clinical trial;
level 2 evidence, case-control or cross-sectional study; level 3 evidence,
case reports or case series, expert opinion; .–, insufficient evidence
found