WILDLIFE DISEASES AND HUMANS
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Robert G. McLean
Chief, Vertebrate Ecology Section
Medical Entomology & Ecology Branch
WILDLIFE DISEASES
Division of Vector-borne Infectious
Diseases
National Center for Infectious Diseases
AND HUMANS
Centers for Disease Control and
Prevention
Fort Collins, Colorado 80522
INTRODUCTION GENERAL PRECAUTIONS Precautions against acquiring fungal
diseases, especially histoplasmosis,
Diseases of wildlife can cause signifi- Use extreme caution when approach- should be taken when working in
cant illness and death to individual ing or handling a wild animal that high-risk sites that contain contami-
animals and can significantly affect looks sick or abnormal to guard nated soil or accumulations of animal
wildlife populations. Wildlife species against those diseases contracted feces; for example, under large bird
can also serve as natural hosts for cer- directly from wildlife. Procedures for roosts or in buildings or caves contain-
tain diseases that affect humans (zoo- basic personal hygiene and cleanliness ing bat colonies. Wear protective
noses). The disease agents or parasites of equipment are important for any masks to reduce or prevent the inhala-
that cause these zoonotic diseases can activity but become a matter of major tion of fungal spores.
be contracted from wildlife directly by health concern when handling animals Protection from vector-borne diseases
bites or contamination, or indirectly or their products that could be infected in high-risk areas involves personal
through the bite of arthropod vectors with disease agents. Some of the measures such as using mosquito or
such as mosquitoes, ticks, fleas, and important precautions are: tick repellents, wearing special cloth-
mites that have previously fed on an ing, or simply tucking pant cuffs into
1. Wear protective clothing, particu-
infected animal. These zoonotic dis- socks to increase the chance of finding
larly disposable rubber or plastic
eases are primarily diseases acquired crawling ticks before they attach. Ad-
gloves, when dissecting or skinning
within a specific locality, and second- ditional preventive methods include
wild animals.
arily, diseases of occupation and avo- checking your clothing and body and
cation. Biologists, field assistants, 2. Scrub the work area, knives, other your pets for ticks and removing the
hunters, and other individuals who tools, and reusable gloves with soap ticks promptly after returning from in-
work directly with wildlife have an in- or detergent followed by disinfec- fested sites. If possible, avoid tick-in-
creased risk of acquiring these diseases tion with diluted household bleach. fested areas or locations with intense
directly from animal hosts or their ec- mosquito activity during the transmis-
3. Avoid eating and drinking while
toparasites. Plague, tularemia, and sion season. Reduce outdoor exposure
handling or skinning animals and
leptospirosis have been acquired in the to mosquitoes especially in early
wash hands thoroughly when fin-
handling and skinning of rodents, rab- evening hours to diminish the risk of
ished.
bits, and carnivores. Humans have infection with mosquito-borne dis-
usually acquired diseases like Colo- 4. Safely dispose of carcasses and tis- eases.
rado tick fever, Rocky Mountain spot- sues as well as any contaminated
ted fever, and Lyme disease because disposable items like plastic gloves. Equally important preventive mea-
they have spent time in optimal habi- sures are knowledge of the diseases
5. Cook meat from wild game thor- present in the general area and the spe-
tats of disease vectors and hosts.
oughly before eating. cific habitats and times of year that
Therefore, some general precautions
should be taken to reduce risks of 6. Contact a physician if you become present the greatest risk of exposure.
exposure and prevent infection. sick following exposure to a wild Knowledge of and recognition of the
animal or its ectoparasites. Inform early symptoms of the diseases and
the physician of your possible expo- the conditions of exposure are essen-
sure to a zoonotic disease. tial in preventing severe illness. Also
PREVENTION AND CONTROL OF WILDLIFE DAMAGE — 1994
Cooperative Extension Division
Institute of Agriculture and Natural Resources
University of Nebraska - Lincoln
United States Department of Agriculture
Animal and Plant Health Inspection Service
Animal Damage Control
A-25
Great Plains Agricultural Council
Wildlife Committee9
40 4
81
5 236
5 125 56 982
108 34
92 336
11 16 VT-1
31 17
17 29 NH-4
27 34 MA-14
55 25 242
40 RI-0
496
23 CT-200
56 40 NJ-960
134 110
6 44 DE-190
4 73 244 MD-584
367
7
73
Fig. 1. Reported human cases of wildlife rabies in the United States, 1991.
important are medical evaluation and disease. Vaccination of wildlife hosts Australia and Antarctica are free of it.
treatment with proper antibiotics. For as a means of reducing zoonotic dis- Most human cases have been con-
example, if you become ill following eases is currently being investigated tracted from rabies-infected dogs. In
some field activity in a known plague- and may soon be available for diseases the United States, human cases have
endemic area and you recognize the like rabies. decreased to an average of one person
early symptoms of the disease, seeking per year (75% of cases are acquired
medical care and informing the attend- outside the United States). Reduction
ing physician of your possible expo- WILDLIFE DISEASES in human rabies is likely linked with
sure to plague will aid in the correct OF PUBLIC HEALTH the intensive control of dog rabies
treatment of your illness and reduce CONCERN during the 1950s and 1960s through
the risk of complications or even massive vaccination campaigns, stray
death. dog control programs, and improve-
Directly Transmitted ment in human treatment following
In addition to taking personal precau- Diseases exposure. Nevertheless, thousands of
tions, risk of acquiring vector-borne
people in the United States continue to
diseases can be reduced in specific
Rabies receive treatment every year for pos-
locations through area-wide applica-
sible exposure to rabies virus by ani-
tions of insecticides to control mos- Rabies is an acute disease, caused by a mal bites. Most of the treatments are
quito or flea vectors or acaricides to virus (rhabdovirus), that can infect all still due to dog and cat bites; however,
control tick vectors. Reduction in host warm-blooded animals, and is usually these pet species have the lowest
populations (for example, rodents) and fatal. Certain carnivorous mammals occurrence of reported rabies among
their ectoparasites (fleas or ticks) may and bats are the usual animal hosts all animal species tested.
be needed to control transmission of (Fig. 1; Table 1). Rabies occurs
such diseases as plague or Lyme throughout most of the world; only
A-26Rabies in wildlife increased dramati- that moves (including inanimate for only a few days before clinical
cally during the 1960s and now objects), bewilderment, and aimless signs appear. Exceptions occur in a
accounts for most of the reported ani- wandering. Unusual barking, crying, few species of bats and in a unique Af-
mal rabies cases (91% in 1991). Some of and frothing at the mouth are addi- rican virus strain found in dogs. The
the increase in reporting was due to tional signs, which are the result of length of the incubation period (from
real increases in the number of cases, paralysis of the throat muscles. Occa- the time the animal is bitten until clini-
and some was due to an increased sionally, rabid bats are encountered cal rabies appears) is usually 2 to 3
awareness of wildlife rabies, particu- prostrate or fluttering on the ground, weeks, but varies from 10 days to
larly in striped skunks, raccoons, and unable to fly; they should be handled several months.
bats. In 1991, 6,975 cases of animal with care because they can still bite
Handling of Suspect Animals and
rabies were reported in 49 states, the and transmit rabies. Some rabid bats,
Diagnosis. Use caution when
District of Columbia, and Puerto Rico. particularly solitary species like the
approaching a suspected rabid animal
Raccoons (44.2%), striped skunks hoary bat, are aggressive and have
since many are still aggressive and can
(29.7%), and various species of bats been known to attack people. In
bite even if paralyzed. If the animal is
(9.9%) continued to be the major hosts. domestic animals, rabies should be
still alive, it should be killed humanely
Red and gray foxes (4.6%), other wild- suspected if there is any change in nor-
without damaging the head. To con-
life species (2.8%), and domestic ani- mal habits, such as sudden change in
firm whether an animal is infected
mals (8.9%) comprise the remainder of disposition, failure to eat or drink, run-
with rabies, the animal must be sub-
hosts. During the last 2 years, raccoons ning into objects, or paralysis.
mitted to the local health department
replaced striped skunks as the major
Transmission. Rabies virus is trans- or state diagnostic laboratory for
wildlife host in the United States
mitted primarily via the saliva during testing.
because of the continued expansion of
the bite of a rabid animal. However,
raccoon rabies in the northeastern Avoid exposure to any sick or dead
other methods of transmission are pos-
United States. Animal cases are animals that are suspected to have
sible. Accidental exposure of wounds
reported throughout the year, rabies. Handle any dead animal with
or cuts to the saliva or tissues of in-
although the number of cases reported gloves or with a plastic bag that can be
fected animals can occur. The virus is
reaches a seasonal peak for skunks in turned inside-out to cover and contain
also present in various body organs of
March and April, for raccoons in the animal. Avoid direct skin contact
infected animals, especially the brain
April, and for bats in August. with the animal. For large animals
and salivary glands, which poses a
such as skunks and raccoons, remove
Clinical Signs. Rabies is considered health hazard to persons who are field
the head cautiously and seal it in a
almost 100% fatal once clinical signs dressing or performing necropsies on
plastic bag, avoiding contact or aerosol
develop. The disease progresses rap- these animals. In addition, aerosol ex-
exposure. Seal the whole animal or
idly following the appearance of clini- posure has occurred, although rarely,
head inside an additional plastic bag
cal signs, and the animal dies within a in caves containing very large popula-
(double) and keep it cool at all times.
few days. Although abnormal behav- tions of infected bats. Transmission
Do not freeze the specimen unless a
ior is not diagnostic for rabies (other between animals also occurs by inges-
delay of several days is anticipated
diseases, like distemper, cause similar tion of infected tissues and by trans-
before it is examined for rabies. Disin-
behavioral changes), atypical behavior placental passage to offspring.
fect gloves or knives that were in con-
and signs develop following brain
When the virus enters the tissue of a tact with the animal with a strong
infection, and rabies should be sus-
susceptible animal or human, it multi- detergent or bleach or dispose of them.
pected whenever wild animals display
plies at the bite or inoculation site and For transport to the laboratory, place
unusual behavior.
travels slowly up nerve fibers to the the double-wrapped specimen in a
Infected animals usually display either part of the brain that controls the bit- leak-proof container with a coolant
“furious” or “dumb” rabies, although ten area. The virus multiplies there (not wet ice). Send the container by
some animals progress through both and spreads to other parts of the brain bus or other prearranged transporta-
stages. Skunks, raccoons, foxes, and and eventually produces a variety of tion. Include information about the
other canids usually have furious signs in the infected animal or person. specimen (species, date, geographic
rabies and are unduly aggressive The virus also spreads from the brain data, behavior) and the names,
before convulsions and paralysis set in. to other tissues, particularly to the sali- addresses, and telephone numbers of
Some animals, however, have dumb vary glands, where it multiplies and is the person submitting the specimen
rabies and proceed to tremors and released into the saliva. The virus is and of anyone exposed to the animal.
convulsions without agitation or perpetuated in nature when an in-
aggression. Other behavioral changes fected animal with virus in its saliva To test for rabies, a fluorescent anti-
include friendliness or loss of fear, bites another animal. body (FA) test is performed directly on
appearance in the daytime for some brain tissue to distinguish rabies virus
The virus is rarely present in the sali- from other disease agents (like distem-
typically nocturnal species (skunks,
vary glands without first occurring in per virus) that could be present in the
bats), unprovoked attacks on anything
the brain and is present in the saliva animal’s brain. In some states, brain
A-27material is inoculated into mice to rodents are the natural reservoirs for and neurological symptoms may
demonstrate virus for those specimens viruses in this group and these viruses appear if treatment is delayed.
that resulted in human exposure. are found worldwide. Infected rodents
Trichinosis is contracted by eating
shed virus in their urine, feces, and/or
If a person or pet is exposed to an ani- infected meat which contains the
saliva and can remain chronically
mal suspected of having rabies but encysted parasites. The parasites may
infected. The contaminated excreta
that has not been captured, record a remain infectious in meat which is raw
from infected rodents are thought to
description of the suspect animal (spe- or poorly cooked.
be the source of virus for aerosol and
cies, behavior) and provide the
direct (animal bite) transmission to Trichinosis is caused by a nematode
description to public health officials or
other rodents and humans. parasite which produces the disease in
the attending physician to determine
humans and domestic and wild ani-
possible treatment. The recent discovery of a possible new
mals. Evidence indicates that nearly all
Prevention and Treatment. The hantavirus in the southwestern United
mammals are susceptible to infections
best treatment for rabies is prevention. States and its apparent increased viru-
with this parasite, which encysts in the
Individuals at high risk of exposure to lence, has heightened the awareness of
muscle of the host and is then trans-
rabies, such as wildlife biologists, and concern for rodent-associated dis-
mitted through consumption of
game wardens, animal control officers, eases. It produces produces respira-
infected flesh. As would be expected,
animal handlers, and veterinarians tory distress and potential death in
the disease is most common in wild
should be vaccinated before potential humans. Human cases and deaths
carnivores and scavengers.
exposure. Safe and highly effective from this viral infection were first
vaccines are available through a physi- reported in 1993 in the Four Corners As with other wildlife diseases,
cian or the local health department. area of Arizona, Colorado, New trichinosis is difficult to control in
Mexico, and Utah and, more recently, nature. However, certain steps can be
First aid should immediately be pro- throughout the United States. Prelim- taken to decrease the problem. Car-
vided to a person who has been bitten inary information has incriminated the casses of carnivores and other meat-
by or had contact with a potentially deer mouse (Peromyscus maniculatus) eating species should not be discarded
rabid animal. Scrub the exposed site, as the natural reservoir and source of in the fields or woods, but should be
including bite wounds, with soap and human infection in that region. Indi- made unavailable by burying or other
water or water alone and flush thor- viduals trapping and handling small means. These carcasses also should not
oughly. Then apply a strong first aid rodents in this region should take be fed to swine, dogs, or other domes-
solution (iodine) or cream. First aid increased precautions to reduce their tic animals. Open garbage dumps
treatment is the most effective method exposure to this virus. They should at should be replaced by the landfill type
of preventing infection by the rabies least wear surgical gloves and masks or other methods of disposal where
virus but should not preclude medical when processing rodents (contact wildlife will not have access to meat
attention from a physician, hospital CDC Hotline for more detailed and scraps. If open garbage dumps cannot
emergency room, or the local health thorough safety information). Rodent be eliminated, rodent control pro-
department. Contact your physician or control with careful handling and dis- grams should be initiated and the
health department as soon as possible posal of carcasses should be instituted areas fenced to prevent scavenging by
to determine dosage of rabies vaccine at campsites or in cabins before they larger animals such as foxes. These
and whether antirabies serum is are occupied. The premises should be steps would markedly reduce the
required. Inform the health care pro- sprayed with detergents or diluted problem of trichinosis in wildlife in the
fessionals about the rabid animal and bleach before thorough cleaning. Wet- United States.
the circumstances of the exposure mopping is recommended. Dry
(species of animal involved and its If carnivorous or omnivorous wildlife
sweeping and vacuuming may
behavior, if the attack or bite from the such as bears, bobcats, opossums,
increase risk of producing airborne
animal was provoked, and what type raccoons, or feral pigs are consumed
particles. Rodent harborage should be
of first aid was administered). by humans, the meat should be
removed from premises and from the
properly prepared by cooking,
surrounding area. Exclude rodents
Hantavirus freezing, or curing to destroy any
where possible.
viable trichinae. Cooking to an internal
Hantavirus includes a group of viruses temperature of 137oF is deemed
that can cause a febrile illness in hu- Trichinosis
sufficient for pork, while freezing at
mans which can be accompanied by Trichinosis may result in diahrrea, 5oF for 20 days, -10oF for 10 days, or -
kidney, blood, or respiratory ailments sudden edema of the upper eyelids, 20oF for 6 days will kill trichinae.
and can sometimes be fatal. The febrile photophobia, muscle soreness and Curing should follow approved
illness includes fever, headache, pain, skin lesions, thirst, sweating, government regulations.
muscle aches, nausea, vomiting, and chills, and weakness. Other respiratory
lower back pain. Field and commensal
A-28Mosquito-borne the Mississippi River, EEE occurs east other exotic game birds, house spar-
of the Mississippi River but mostly rows, red-winged blackbirds, whoop-
Encephalitis along the Atlantic and Gulf coasts and ing cranes, and other species. The
Encephalitis is a disease caused by north-central states, and CE occurs in wildlife hosts for LAC virus are the
mosquito-borne viruses (arboviruses) California and the eastern United eastern chipmunk, tree squirrels, and
that affect the central nervous system. States (LAC type). Human cases of foxes. The natural hosts for the other
Infections range from unapparent to arbovirus infection have a seasonal three viruses are mostly songbirds,
mild, nonspecific illnesses (fever, head- occurrence from mid- to late summer. although squirrels and jackrabbits may
ache, musculoskeletal pain, and mal- be involved in WEE transmission.
These distinct viruses naturally infect a
aise) to occasionally severe illness of variety of birds and mammals and are No treatment or commercial vaccine is
the central nervous system resulting in transmitted between animals by mos- available for humans, but vaccines for
permanent neurologic damage and quito vectors. Occasionally, infected WEE and EEE are readily available for
possibly death. The four major types of mosquitoes will feed on human or horses. The best preventive measures
encephalitis in the United States equine hosts that are “dead ends” for are personal protection against mos-
include St. Louis encephalitis (SLE), the viruses, with little or no chance of quito bites, especially avoiding expo-
California encephalitis (CE primarily subsequent transmission to other mos- sure to mosquitoes during early
includes the LaCrosse virus [LAC]), quitoes. These viral infections may, evening hours, and the use of repellents.
eastern equine encephalitis (EEE), and however, result in severe illness or Mosquito populations can be reduced
western equine encephalitis (WEE). death in humans or horses (EEE and in an area by eliminating breeding sites
The distribution of these arboviruses WEE). Only EEE and occasionally for vector species. Killing adult mos-
varies (Fig. 2). SLE occurs throughout WEE viruses adversely affect wild ver- quitoes with areawide applications of
the United States (an epidemic oc- tebrates; for example, EEE causes insecticides has been most effective in
curred in central Florida in 1990 and death in ring-necked pheasants and preventing epidemics.
Arkansas in 1991), WEE occurs west of
SLE CE
EEE WEE
Fig. 2. Distribution of mosquito-borne encephalitis in the United States, 1964 to 1992; (a) St. Louis encephalitis (SLE); (b) California encephalitis (CE);
(c) eastern equine encephalitis (EEE); and (d) western equine encephalitis (WEE).
A-29130
14
17
6
88
255
907
21
Fig. 3. Distribution of Colorado tick fever (human cases) in the United States, 1980 to 1988. (Solid line outlines distribution of Dermacentor andersoni.)
Tick-borne Diseases of the Rocky Mountain wood tick Rocky Mountain Spotted Fever
(Dermacentor andersoni) or by D. (Tick-borne Typhus)
Colorado Tick Fever occidentalis in California. The virus is Rocky Mountain spotted fever (RMSF)
maintained in nature through trans- is a moderate to severe illness caused
Colorado tick fever (CTF) is an acute
mission by immature stages of ticks to by a rickettsia (Rickettsia rickettsii). The
and rather benign disease caused by a
various species of small mammals, disease is distinguished by a sudden
virus (coltivirus) that is transmitted to
particularly chipmunks, ground squir- onset of high fever, severe headache,
humans by ticks. Symptoms are usu-
rels, and deer mice during the spring muscle pain, and a red rash starting on
ally limited to high fever, headache,
and summer months. The virus sur- the extremities about 3 to 6 days after
muscle aches, and lethargy, but the
vives the winter in infected tick onset of symptoms and extending to
symptoms are frequently biphasic and
nymphs and adults. The habitats that the palms of hands and soles of feet
recurring. The disease is confined to
support the rodent hosts and tick vec- and then to the rest of the body. Delir-
the mountains or highland regions of
tors of the virus in the disease endemic ium, coma, and death occur in about
eight western states and western
region contain rocky surfaces with 1% to 2% of cases (15% to 20% in
Canada (Fig. 3). About 150 to 200 cases
moderate shrub cover and scattered untreated cases). The disease is trans-
are reported each year; 1,438 cases
pines. mitted to humans in the United States
were reported from 1980 to 1988 in
eight western states, 63% of them in Avoid tick-infested habitats during by several hard tick (Ixodidae) species;
Colorado. CTF is transmitted to spring and early summer and use per- D. andersoni in the Rocky Mountain
humans during the spring and early sonal protection against ticks. No vac- region, D. variabilis in the east and
summer by the bite of the adult stage cines or treatment are available. southeast, and Amblyomma americanum
A-30in the south-central states. In 1990, 649 Lyme Disease symptoms, including heart, nervous
cases of RMSF were reported from all system, and joint manifestations, may
Lyme disease is caused by a spirochete
regions of the United States, although develop in untreated individuals. The
bacterium (Borrelia burgdorferi) that is
more cases were reported in the south- joint pain and swelling usually occur
transmitted to humans by hard ticks.
Atlantic and south-central states (Fig. one or more months after infection,
Early symptoms include a flu-like ill-
4). The natural hosts for the rickettsia may involve one or more joints, and
ness with headache, slight fever, mus-
are a variety of wild rodents, although may recur in different joints; the knee
cle or joint pain, neck stiffness, swollen
rabbits and wild and domestic carni- joint is most frequently affected. Do-
glands, jaw discomfort, and inflamma-
vores are involved in some cases. The mestic animals may be affected as
tion of the eye membranes. A diagnos-
rickettsia survive the winter months in well.
tic rash, erythema migrans (EM),
the tick vector and may be maintained
occurs in 65% to 75% of the cases. The In 1992, 9,695 cases of Lyme disease
by transovarial transmission from the
rapidly expanding red rash starts at were reported in 44 states (Fig. 5).
female adult tick to its offspring.
the tick bite site and expands to a Most cases were reported in the north-
Avoid tick-infested areas and use per- nearly circular lesion of about 1 to 8 eastern and upper midwestern states
sonal measures to protect against tick inches (2 to 20 cm). It often has a bulls- where the vector is the deer tick (Ixodes
bites. No vaccine is presently licensed eye appearance with central clearing scapularis) and where transmission is
for public use, but antibiotic treatment and/or darkening around the edge. predominately in residential commu-
is effective and should be initiated Additional smaller skin lesions may nities. Other vectors are I. pacificus on
without waiting for laboratory confir- appear at other sites of the body and the West Coast and possibly A.
mation of clinical diagnosis. may last for days or weeks. Later americanum in the Southeast and in
2
4
1
1 2 17
1
5 NH-1
1 2 MA-17
3 3 2 RI-0
1 1 CT-2
1 13 25
36 11 NJ-8
178 DE-1
70 58 MD-23
1
1 22 43
6 13 18
6 3
3
Fig. 4. Distribution of Rocky Mountain spotted fever (human cases) in the United States, 1990.
A-3114
0 1 1
201
13
2 525
1 3370
5
33 1119 NH-49
1 15 32
41 21 VT-9
6 0 14 CT-1760
231 18 150 28 123 MA-212
85 RI-274
26 33 NJ-681
0 2 21 2 DE-218
23 MD-186
10
0
73 7
24
Fig. 5. Distribution of Lyme disease (human cases) in the United States, 1992.
south-central states. Transmission in cycle. The engorged nymphs drop to knowledgeable about the symptoms of
these other regions of the United States the ground and molt into adult ticks Lyme disease, and seek medical care
may be more sporadic and occur dur- which are active during the fall and and treatment if infected.
ing outdoor activities related to recre- following spring and feed on large
ation and occupation. Acquisition of mammals, primarily deer. Deciduous Tularemia
Lyme disease by humans peaks during forest is the predominant habitat for Tularemia is caused by the bacteria
the summer months when the tick the tick vector and vertebrate hosts in Francisella tularensis and is character-
nymphs are feeding on hosts. Because the Northeast and Midwest. Other ized by sudden onset of high fever and
of its small size, the attached nymph prime habitats include forested areas chills, joint and muscle pain, and pros-
frequently goes unnoticed and is not interspersed with residential develop- tration. Slow-healing sores or lesions
removed. The transmission cycle of ment and grass and shrub areas, par- develop at the site of entry of the bac-
Lyme disease begins when larvae ticularly along forest edges. teria (or arthropod bite). Inflammation
acquire spirochetes while feeding on
Patients treated with appropriate anti- and swelling of nearby lymph nodes
infected white-footed mice, chip-
biotics during the early stages of the follow.
munks, other rodents, and birds.
disease usually have rapid and com-
Engorged larvae drop to the ground, Tularemia is endemic throughout
plete recovery. Even patients treated
molt to the nymphal stage, and wait North America (Fig. 6). Most of the
during later stages generally respond
until the following summer to attach to 100 to 300 cases reported each year are
well and recover. No vaccine is avail-
and transmit spirochetes to susceptible from the area between the Rocky
rodents, birds, larger mammals, and able except for domestic dogs. Avoid
Mountains and the Mississippi River
humans. Uninfected larvae subse- locations with ticks during seasonal
(especially Arkansas and Missouri).
quently feed on these wild vertebrate activity periods, use personal mea-
Most cases are acquired during the
hosts to complete the transmission sures to protect against ticks, become
summer months from vector transmis-
A-32sion; however, a second peak of cases ments; and scratches or bites from ticks. This species of tick is active at
occurs during the winter and is prob- infected animals. Use personal protec- night. Since it feeds rapidly and its bite
ably associated with rabbit hunting tion measures against ticks and prac- is relatively painless, it may go unno-
and carnivore trapping. tice good sanitation procedures when ticed. The ticks feed on humans when
handling wild animals, especially rab- the rodents disappear from the cabin
The bacteria is maintained in rabbits,
bits. Promptly seek medical care and nests because of rodent control mea-
hares, rodents, and birds by tick trans-
treatment if symptoms develop. sures or death from other diseases.
mission. The natural reservoir for the
Most human cases occur during the
bacteria includes infected ticks and Relapsing Fever summer months when the cabins are
animal species that are less susceptible
Relapsing fever can be caused by sev- in use. Sporadic cases are reported pri-
and thus survive acute infections.
eral Borrelia spirochete bacteria, which marily in the mountainous regions of
Hard ticks, primarily D. andersoni, D.
are related to the Lyme disease spiro- the western United States and British
variabilis, and Haemaphysalis leporis-
chete and are transmitted by soft ticks Columbia; 159 cases were reported
palustris, and some flies, especially the
(Argasidae). Symptoms resemble during 1985 to 1991 in 10 western
deerfly (Chrysops discalis), can subse-
Lyme disease except for the absence of states (Fig. 7). Two outbreaks occurred
quently transmit the disease to
the diagnostic rash and the presence of among tourists and staff staying in
humans. Tularemia can also be trans-
recurring fever. The most common cabins at the Grand Canyon in Arizona
mitted directly to humans. Transmis-
type is caused by B. hermsii. Most hu- in 1973 and 1990. Inspect cabins for ro-
sion routes include drinking contami-
man cases of this type of relapsing dent use and nests, promptly remove
nated water; eating contaminated food
fever have been associated with log nests, and treat cabins with insecti-
or improperly cooked game meat;
cabins or houses containing rodent cides or fumigate to kill any remaining
inhaling aerosols contaminated with
nests (particularly of chipmunks and ticks. Rodent-proof cabins to prevent
rodent urine, feces, or dust; cuts from
pine squirrels) and Ornithodoros hermsi rodent entry.
contaminated knives or other instru-
Incidence rate per
100,000 people.
no cases
0.01 to 0.24
0.25 to 0.74
> 0.75
Fig. 6. Distribution of tularemia (human cases) in the United States, 1991 (191 cases reported).
A-3326
15
14
6
3 18
60
9 2
6
Fig. 7. Distribution of relapsing fever (human cases) in the United States, 1985 to 1991.
Two other species of relapsing fever appears less frequently and for a much Babesiosis is a protozoan disease with
spirochetes are transmitted occasion- shorter duration. From 1986 to 1991, gradual onset of fever, sweating, loss
ally to humans in the western United 262 cases and 4 fatalities were reported of appetite, fatigue, general muscle
States by Ornithodoros ticks. The spiro- in 23 states, the majority occurring in ache, and possibly prolonged anemia.
chete B. parkeri is transmitted by O. Missouri and Oklahoma. Use personal The disease can be severe and some-
parkeri, mostly in California, and B. protection against ticks and seek medi- times fatal. A protozoan, Babesia
turicatae by the tick O. turicata. Five cal care and treatment if sick. microti, is transmitted among wild
humans were infected with B. turicatae rodents, particularly white-footed
Powassan encephalitis is caused by a
in Texas in 1990 following exploration mice, by the tick I. scapularis along the
virus (flavivirus) which is transmitted
of a cave containing infected ticks. For coastal areas of New England and on
by the ticks I. cookei, D. andersoni, and
prevention, use personal protection adjacent offshore islands. This tick
other Ixodes spp. Symptoms include
against tick exposure. If sick with may be infected occasionally with both
the sudden onset of fever, sore throat,
relapsing fever, seek medical care and B. microti and the Lyme disease spiro-
sleepiness, headache, and disorienta-
appropriate antibiotic treatment. chete. Use personal protection mea-
tion. Encephalitis, meningitis, and,
sures to prevent tick exposure and
occasionally, partial paralysis may
Other Tick-borne Diseases seek medical care if sick.
develop. Natural hosts are marmots,
Three other tick-borne diseases occur sciurid rodents, rabbits, hares, carni- Personal Protection
in the United States. Human ehrlichio- vores, and possibly birds. Only 19
cases have been reported, all in New The following personal measures can
sis is a recently recognized disease
York, Pennsylvania, Ontario, and Que- protect against tick-transmitted
caused by a rickettsia, Ehrlichia chaf-
bec. Use personal protection to reduce diseases:
feensis. It is probably transmitted by
ticks. Symptoms are similar to those of exposure to ticks. No treatment is 1. When possible, avoid tick-infested
RMSF: an acute fever with headache, available. areas.
muscle ache, and nausea. A rash
A-342. To better see crawling ticks, tuck Flea-borne Diseases form, with 25% to 60% fatality in
pant legs into socks and tape the untreated cases. In the United States,
tops of socks over pant legs. Wear Plague plague is maintained in wild rodent
light-colored clothes. populations in the western states by
Plague is an acute disease caused by
flea transmission between rodents. Syl-
3. Use tick repellent on exposed skin the bacteria Yersinia pestis. Humans
vatic plague may persist in these ani-
(DEET) or treat clothes with usually become infected by the bites of
mal populations with varying severity,
permethrin. Follow label instruc- infected fleas but also directly from
depending on the species’ resistance.
tions for use. exposure to tissues or body fluids
Prairie dogs are susceptible to sudden
4. Check yourself frequently for ticks from diseased animals, especially
die-offs. Outbreaks of plague have
and remove them. when skinning animals. The disease is
decimated prairie dog colonies in less
characterized by the sudden onset of
5. After outdoor activity, remove and than 1 to 2 years. Rabbits, hares, carni-
fever and chills, followed by the devel-
wash field clothing promptly and vores, and wild ungulates have also
opment of swollen and painful lymph
dry clothes at a high temperature. been infected occasionally. Human
nodes (buboes) in the armpits, groin,
cases of plague are reported most fre-
6. Inspect your body carefully and and other areas 2 to 6 days following
quently in New Mexico, Arizona, Cali-
remove attached ticks with a exposure. In addition to the bubonic
fornia, Colorado, and Oregon (Fig. 8).
pointed tweezers. Grasp ticks as form, septicemic infection may
More than 50% of the 284 cases in the
close to the skin as possible and pull develop and involve other organs.
United States reported from 1970 to
them loose with a slow, steady Secondary infection of the lungs may
1990 were in New Mexico. Use insect
motion. lead to primary plague pneumonia,
repellents on skin or treat field clothes
which then can be transmitted from
7. Inspect pets carefully for ticks and with permethrin. Practice good sanita-
person to person by aerosol. The dis-
remove ticks soon after returning tion procedures when handling ani-
ease may be only mild and short-lived
from the outdoors. mals. Seek medical care and treatment
but frequently progresses to a severe
if sick.
1
1
10
1
2
4
6 27
28
40 161
3
Fig. 8. Distribution of plague (human cases) in the United States, 1970 to 1990.
A-35Murine Typhus Fever ers, and fish or poultry dealers. In a sanguineus). In this country rickettsial-
recent study in Hawaii, Norway rats, pox has been reported in Boston, West
Murine typhus fever is caused by Rick-
roof rats, and house mice were found Hartford, New York, Cleveland, and
ettsia typhi, a rickettsial organism that
to have high L. icterohemorrhagiae Philadelphia.
occurs throughout the southeastern
carrier rates.
and Gulf Coast states and southern
California. Rats are the reservoir ani- Symptoms of leptospirosis infection Bird-borne Diseases
mals from which the disease reaches range from none to severe, with acute
many humans by way of rat fleas. The fatalities. Many infections are charac- Large roosting concentrations of birds
oriental rat flea, Xenopsylla cheopis, is terized by diarrhea, chills, vomiting, can be noisy, and the associated drop-
considered the most important vector myalgia, and kidney damage. Preven- pings can be a nuisance because of the
of the disease. The causative organism tion is the most important means of objectionable odor and mess. In addi-
enters the bloodstream when feces of dealing with this disease. Proper sani- tion, birds may carry and transmit
infected fleas are scratched or rubbed tation, rodent-proofing, and food stor- diseases to livestock and humans. Col-
into a flea-bite wound or other breaks age and handling are essential. lections of droppings may provide a
in the skin. Murine typhus is similar to Medical attention is typically required. medium for bacterial and fungal
epidemic or louse-borne typhus, but growth that could pose a potential
illness is much milder and the fatality Salmonellosis public health problem. Birds should be
rate in untreated cases is much lower. dispersed or controlled when they
The Salmonella group of bacteria exists form large concentrations near human
nearly everywhere in the environment habitations and are judged to pose a
Commensal Rodent-borne and, unfortunately, several serotypes threat to public health or livestock.
are pathogenic to humans and other
Diseases animals. Salmonellosis can lead to
Concentrations of birds that do not
threaten human health or agriculture
Rats and mice are responsible for the severe cases of gastroenteritis (food are usually better left undisturbed.
spread of over 35 diseases, either poisoning), enteric fever septicemia
directly, through contamination of (blood poisoning), and death. Food Histoplasmosis
human food with their urine or feces, poisoning, the most common malady,
or indirectly, by way of rodent fleas is characterized by a sudden onset of Histoplasmosis is a respiratory disease
and mites. Following are brief descrip- abdominal pain, diahrrea, nausea, and in humans caused by inhaling spores
tions of the more common of these vomiting. Due to the severity of this from the fungus Histoplasma capsula-
diseases. disease, medical attention is typically tum. Birds do not spread the disease
required. directly — spores are spread by the
Rat-bite Fever wind and the disease is contracted by
Salmonella bacteria recognize few host inhalation. Bird droppings enrich the
Rat-bite fever is caused by the bacteria barriers and are transmitted in many soil and promote growth of the fun-
Streptobacillus moniliformis, which is ways. One common form of transmis- gus. Notable sources for histoplasmo-
found on the teeth and gums of rats. It sion is through food contaminated by sis infection include: (1) traditional
is transferred from rats to humans by rat or mouse feces that contain Salmo- bird roosts, (2) poultry farms, (3)
the bite of the rat. The most frequently nella (especially S. typhimurium) organ- enclosed buildings where birds or bats
occurring rat-bite fever in the United isms. It may also be spread by birds, have roosted, and (4) natural or
States is called Haverhill fever. It is which contaminate food with their organic fertilizers. In addition, the fun-
similar to the rat-bite fever of the feces or bacteria carried on their feet. gus can grow in various natural soils,
Orient called sodoku (caused by with or without droppings. In some
Spirillus minus). As with leptospirosis, the most impor-
tant means of reducing the potential of areas, such as the Ohio Valley, histo-
Leptospirosis (Weil’s Disease) this disease is through proper sanita- plasmosis is so widespread that 95% of
tion, rodent-proofing, and food storage the human population becomes
Leptospirosis is a mild to severe infec- and handling. Rodent control through infected, whether associated with
tion that is seldom fatal. Human cases trapping and appropriate use of toxi- birds or not.
of the disease result from direct or cants may also be necessary.
indirect contact with infected urine of Infection by only a few spores gener-
rodents and other animals. The spiro- ally produces a mild case in humans
Rickettsialpox
chetes (Leptospira spp., primarily L. and people are often unaware that
icterohemorrhagiae) are found in con- Rickettsialpox is a mild nonfatal dis- they have contracted the disease
taminated water or on food, and may ease resembling chicken pox. It is (unless it is detected later through a
enter humans through mucous mem- caused by a rickettsia (Rickettsia akari), skin reactivity test or lung X ray that
branes or minute cuts or abrasions of which is transmitted from house mice reveals healed lesions). A more severe
the skin. Thus, Weil’s disease is often to humans by the bite of an infected infection may result in an acute respi-
found in sailors, miners, sewer work- house mouse mite (Liponyssoides ratory illness with flu-like symptoms
A-36(in fact, histoplasmosis is often misdi- formaldehyde before clearing, but this disease spread by pigeons and
agnosed as flu). The most serious option is very expensive. starlings that results in chronic, usually
infections, usually resulting from mas- fatal, meningitis. Various species of
sive spore inhalation, may involve a Ornithosis (Chlamydia psittaci, birds may also play a part in the
dissemination of the fungus through psittacosis) transmission of encephalitis,
the blood stream. Such cases may Ornithosis is an infectious respiratory Newcastle disease, aspergillosis,
become chronic, recurring at later disease caused by Chlamydia psittaci, a toxoplasmosis, pseudotuberculosis,
times, and affect organs other than the viruslike organism that affects avian tuberculosis, and coccidiosis.
lungs. Treatment with an antifungal humans, pets, and livestock. It usually
agent such as amphotericin B or imi- leads to a mild pneumonia- or flu-like
dazole ketoconazole may be pre- Conclusion
infection, but it can be a rapidly fatal
scribed in more severe cases. disease (less than 1% of the cases
Wildlife workers tend to ignore the
Not all blackbird or starling roosts reported in the United States). In
risks associated with handling wildlife
pose immediate public health prob- humans many cases occur that are
species and working in natural envi-
lems related to histoplasmosis. The undetected or incorrectly diagnosed.
ronments. Diseases of wildlife or
histoplasmosis fungus grows readily Pigeons are most commonly associ-
diseases present in their habitats can
in the soil beneath bird roosts, but it ated with the transmission of orni-
infect humans and some can cause
cannot form spores under the acidic thosis to humans. Birds have adapted
serious illness or even death. Becom-
conditions of fresh droppings. An to the disease and show no symptoms,
ing aware of the potential diseases
active, undisturbed roost may only but act as healthy carriers, shedding
present and taking precautions to
give off a few spores. Old or aban- the organism in their feces, which later
decrease exposure will greatly reduce
doned roosts, however, can pose a sig- may become airborne as dust. The dis-
chances of becoming infected with one
nificant threat to human health. After ease may also be contracted from para-
of these diseases. This section provides
the droppings have dried out or been keets, farm poultry, or waterfowl.
a description of the major zoonotic
leached by the rain, the right condi- People working in dry, dusty areas diseases of wildlife in the United States
tions develop for spore release. If the where bird droppings are present, that can also infect humans and gives
soil is stirred up under dusty condi- should wear face masks or respirators information on disease prevention.
tions, as may be the case in land clear- to avoid inhaling airborne avian fecal Other diseases are briefly listed in
ing or bulldozing, massive amounts of material. Spray work areas with water Table 1 or can be found in one of the
spores may be released. Severe epi- and/or disinfectants to minimize the selected references.
demics have occurred in association potential for airborne infections par-
with bird roosts under such condi- You can prevent infection with zoo-
ticles. Medical attention, including
tions. notic diseases and reduce the serious-
antibiotic treatments are recom-
ness of an illness by observing the
Birds in large roosts can be dispersed mended for disease treatment.
following recommendations:
by the use of various frightening
Salmonellosis 1. Become aware of which zoonotic
devices or by roost thinning or clearing
(see Bird Dispersal Techniques). Pre- The Salmonella group of bacteria can diseases are present in your area
cautions should be taken when work- also be transmitted by birds. Refer to and their clinical symptoms.
ing around an old or abandoned roost Commensal Rodent-borne Diseases 2. Obtain any preexposure vaccina-
site. It is wise to test for the presence of (above) for additional information. tions that are available, particularly
histoplasmosis before beginning any for rabies.
work. Wear a self-contained breathing Other Bird-borne Diseases
apparatus or face mask with a dust fil- 3. Take personal precautions to reduce
Pigeons, starlings, sparrows, black-
ter (less than 2 microns) to prevent in- exposure to disease agents and
birds, and other types of birds have
halation of the spores. Wear protective vectors such as ticks, mosquitoes,
been implicated in the transmission of
clothing, gloves, and boots that can be and fleas.
various diseases of significance to
removed and disinfected with forma- humans or livestock. Starlings have 4. Practice good sanitation procedures
lin and washed. If an area that was been shown to be vectors of transmis- when handling or processing
once a bird roost is going to be cleared sible gastroenteritis (TGE) of swine. animals or their products.
or bulldozed, the area should be The virus can be carried in an infective
dampened with water or work should 5. If you become ill, promptly seek
state in the birds’ intestines or on their
be done when the weather is wet or proper medical treatment and
feet for up to 30 hours. It is generally
cold or both. Avoid working under inform the physician about possible
fatal to baby pigs and causes weight
dry, dusty conditions in late summer. exposures.
loss in adults. Starlings may also be
A roost may be decontaminated by involved in the transmission of hog
spraying it with a 3% to 5% solution of cholera. Cryptococcosis is a fungal
A-37Acknowledgments
Portions of this chapter were derived from F. R.
Henderson. 1983. Wildlife diseases and man.
in R. M. Timm, Prevention and Control of
Wildlife Damage. Univ. Nebraska Coop. Ext.
Lincoln.
For Additional
Information
For further information, consult the local or
state health department or contact the CDC
Voice Information System, Centers for Disease
Control and Prevention, Atlanta, Georgia, at
(404) 332-4555.
Acha, P. N., and B. Szyfres. 1987. Zoonoses and
communicable diseases common to man and
animals, 2d ed. Pan Am. Health Org.
Washington, DC. 963 pp.
Adrian, W. J., ed. 1981. Manual of common
wildlife diseases in Colorado. Colorado Div.
Wildl. Denver. 139 pp.
Benenson, A. S., ed. 1990. Control of
communicable diseases in man, 15th ed. Am.
Public Health Assoc. Washington, DC.
532 pp.
Thorne, E. T., N. Kingston, W. R. Jolley, and R. C.
Bergstrom eds. 1982. Diseases of wildlife in
Wyoming, 2d ed. Wyoming Game Fish Dep.
Cheyenne. 353 pp.
Weeks, R. J., and A. R. Stickley, Jr. 1984.
Histoplasmosis and its relation to bird
roosts: a review. Denver Wildl. Res. Center.
Bird Damage Res. Rep. No. 330. Denver,
Colorado. 23 pp.
Editors
Scott E. Hygnstrom
Robert M. Timm
Gary E. Larson
A-38Table 1. Some important wildlife diseases that affect humans.
Disease Parasite Method of Wildlife Type of Human
(Agent) Transmission Hosts Illness
Direct
Rabies Virus Animal bite, Striped skunk, raccoon, Paralysis, convulsions,
(rhabdovirus) aerosol foxes, bats, and other coma, death
mammals
Hantavirus Virus Aerosol, Deer mice, other Fever, headache, muscle
(hantavirus) animal bite wild and commensal aches, nausea, vomiting,
rodents back pain, respiratory
syndrome
Leptospirosis Bacteria Urine contamination, Commensal and wild Fever; jaundice; neuro-
(Leptospira spp.; ingestion rodents, rabbits, fox, logic; pain in abdomen,
icterohemorrhagiae) skunk, raccoon, joints, or muscles;
opossum, deer nausea; may be fatal
Brucellosis Bacteria Contamination, Hoofed animals Intermittent fever, chills,
(Brucella spp.; ingestion (coyote) headache, body aches,
abortus) (milk, etc.) weakness, weight loss
Rat-bite fever Bacteria Rodent bite Commensal rodents Abrupt onset with chills
(Streptobacillus and fever, headache,
moniliformis) muscle ache, followed
by rash on legs and
arms, arthritis
Salmonellosis Bacteria Ingestion of bacteria Rodents, swine, cattle, Sudden onset of head-
(Salmonella spp.) in food contaminated wild birds, poultry, ache, fever, abdominal
with feces pet turtles pain, nausea, diarrhea,
vomiting
Ornithosis Chlamydia Inhalation of Parrot and sparrow- Fever, chills, headache,
(Psittacosis) (Chlamydia contaminated air like birds, pigeons, muscle pain, loss of
psittaci) waterfowl, domestic appetite, sweating,
birds pneumonia
Histoplasmosis Fungus Inhalation of None, grows in soil Mild fever and
(Histoplasma spores enriched by feces influenza-like illness,
capsulatum) under bird and bat pneumonia, hepatitis,
roosts endocarditis, death
Cryptococcosis Fungus Inhalation None, grows in Meningitis; lung, liver,
(Cryptococcus is suspected droppings in and bone infection; skin
neoformans) pigeon nests lesions or ulcers
Trichinosis Nematode worm Ingestion of uncooked Swine, bear, wild and Nonspecific gastroenter-
(Trichinella spiralis) meat containing larval domestic carnivores, itis, loss of appetite,
cysts wild and domestic nausea, diarrhea, swollen
rodents eyelids, fever, chills,
muscle aches
Ascarid Nematode Ingestion of nematode Raccoon Larval stage invades and
roundworm (Baylisascaris eggs (raccoon feces damages body organs,
procyonis) contamination) including brain
Direct and Indirect
Plague Bacteria Contamination from Wild rodents (prairie Fever, headache, severe
(Yersinia pestis) skinning animals, dogs, ground and tree discomfort, shaking
fleas squirrels, chipmunks), chills, pain in groin or
rabbits, carnivores arm pits (swollen lymph
nodes), death
A-39Table 1. Some important wildlife diseases that affect humans (continued).
Disease Parasite Method of Wildlife Type of Human
(Agent) Transmission Hosts Illness
Direct and Indirect
Tularemia Bacteria Contamination from Wild rodents, rabbits, Mild illness to severe
(Francisella skinning animals, hares, carnivores, meningitis, pneumonia,
tularensis) ticks, biting insects birds, hoofed animals ulcer at inoculation site,
swollen lymph nodes,
death
Indirect
Tick-borne
Colorado tick fever Virus (coltivirus) Tick, Dermacentor Wild rodents (sciurids, High fever, headache,
andersoni, D. porcupine), hares, muscle ache, lethargy,
occidentalis rabbits, marmots, biphasic symptoms
carnivores
Rocky Mountain Rickettsia Tick, D. andersoni, Wild rodents, rabbits, Rapid onset, fever, head-
spotted fever (Rickettsia rickettsii) D. variabilis, hares, carnivores, ache, muscle aches,
Amblyomma birds nausea, vomiting,
americanum, abdominal pain, rash,
Haemaphysalis loss of muscle control,
leporispalustris possibly fatal
Ehrlichiosis Rickettsia Tick, species Unknown, possibly Fever, headache, nausea,
(Ehrlichia unknown dogs and other vomiting, muscle aches,
chaffeensis) carnivores fleeting rash
Lyme disease Bacteria Tick, Ixodes scapularis, Wild rodents Skin lesion (EM), fever,
(Borrelia I. pacificus, A. (Peromyscus, chip- headache, fatigue,
burgdorferi) americanum munks), raccoon, deer, muscle ache, stiff neck,
rabbits, birds cardiac and neurologic
manifestations, arthritis
Relapsing Bacteria Tick, Ornithodoros Wild rodents (chip- Rapid onset, severe
fever (Borrelia hermsii, B. hermsi, O. parkeri, munks, tree squirrels), headache, muscle weak-
parkeri, B. turicatae) O. turicata particularly in cabins ness, rigor, joint pain,
and caves recurring fever
Babesiosis Protozoa Tick, I. scapularis Wild rodents (white- Gradual onset, loss of
(Babesia microti) footed mice, meadow appetite, fever, sweating,
vole) fatigue, general muscle
aches, prolonged
anemia, sometimes fatal
Tularemia (listed above)
Mosquito-borne
St. Louis Virus Mosquito, Culex pipiens Birds (mostly song- Fever, headache,
encephalitis (flavivirus) complex, Cx. tarsalis, birds and waterbirds), musculoskeletal aches,
Cx. nigripalpus some rodents malaise, low fatality
Eastern equine Virus Mosquito, Culiseta Birds (mostly song- Fever, intense headache,
encephalitis (alphavirus) melanura, Aedes spp. birds and waterbirds), nausea, vomiting,
bats muscle, aches, confusion,
coma, high fatality
A-40Table 1. Some important wildlife diseases that affect humans (continued).
Disease Parasite Method of Wildlife Type of Human
(Agent) Transmission Hosts Illness
Indirect
Western equine Virus Mosquito Birds (mostly song- Fever, headache, nausea,
encephalitis (alphavirus) Cx. tarsalis birds and waterbirds), vomiting, malaise, loss
jackrabbits, rodents of appetite, convulsions,
low fatality
California Virus Mosquito Eastern chipmunk, Fever, irritability, head-
encephalitis (bunyavirus) Ae. triseriatus tree squirrel, red fox, ache, nausea, vomiting,
(LaCrosse) deer mouse loss of muscle control,
confusion, coma, low
fatality
Louse-borne
Louse-borne Rickettsia Body louse Humans, flying Onset variable, fever,
typhus (Rickettsia Pediculus humanus, squirrels headache, chills, general
prowazekii) animal contact pains, prostration, skin
rash after 5 to 6 days
Flea-borne
Flea-borne typhus Rickettsia Rat flea Domestic rats, wild Fever, severe headache,
(Murine) (Rickettsia typhi) Xenopsylla cheopis rodents, opossum chills, general pains,
possibly skin rash
Plague (listed above)
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