Page 1571 - Small Animal Internal Medicine, 6th Edition

CHAPTER 99 Zoonoses 1543

commonly subclinically infected and pass the organism into culture or PCR assay. Dogs with clinical signs of brucel-
the environment in urine, feces, milk, and parturient dis- losis should be evaluated serologically for Brucella infec-
VetBooks.ir charges. Seropositive dogs have been detected, but zoonotic tion with the 2-mercaptoethanol rapid slide agglutination
card test. Seronegative dogs are unlikely to harbor Brucella
transfer to humans from dogs has not been documented.
Infection of cats most commonly occurs after tick exposure,
should have results confirmed by tube agglutination or agar
ingestion of contaminated carcasses, or aerosolization from unless the clinical syndrome is peracute. Seropositive dogs
a contaminated environment. Fever, anorexia, and lethargy gel immunodiffusion. Long-term antibiotic treatment (tet-
developed in some experimentally infected cats. Infection racyclines, aminoglycosides, quinolones) usually does not
has been associated with abortion in cats, but the organism clear the infection, thus some recommend euthanasia of
can also be isolated from normal parturient cats. Infection infected dogs. Ovariohysterectomy or castration will lessen
of cats appears to be common; 20% of cats from a shelter in contamination of the environment. Genital tract secretions
southern California and 20% of cats in Maritime Canada should be avoided.
were seropositive, the organism was grown from the vagina
of healthy cats in Japan, and DNA of the organism was
amplified from uterine tissues of cats in Colorado (Cairns SHARED VECTOR ZOONOSES
et al., 2007).
Human illness associated with direct contact with Some zoonotic agents are transmitted between animals and
infected cats occurs after aerosol exposure to the organism humans by shared vectors such as fleas, ticks, or mosquitoes.
passed by parturient or aborting cats; clinical signs develop Rickettsia rickettsii (ticks), Rickettsia felis (fleas), Ehrlichia
4 to 30 days after contact. Humans commonly develop acute spp. (ticks), Anaplasma phagocytophilum (ticks), Borrelia
clinical signs similar to those associated with other rickettsial burgdorferi (ticks), Bartonella spp. (fleas and ticks), Dipy-
diseases, including fever, malaise, headache, pneumonitis, lidium caninum (fleas), Dirofilaria immitis (mosquitoes),
myalgia, and arthralgia (Marrie, 1995). After primary infec- and West Nile virus (mosquitoes) are examples of vector-
tion, chronic Q fever develops in approximately 1% and can borne zoonoses common in the United States. For the flea-
manifest as hepatic inflammation or valvular endocarditis. and tick-borne zoonoses, the pet brings the vector of the
Tetracyclines, chloramphenicol, and quinolones are usually organism into the environment, resulting in exposure of the
effective therapeutic agents in humans. Gloves and masks human being. Veterinary healthcare providers could have
should be worn when attending to parturient or aborting a slightly increased risk of exposure because they handle
cats. People who develop fever or respiratory tract disease many animals infested with fleas and ticks. However, the
after exposure to parturient or aborting cats should seek vector, not direct contact with the infested animal, results
medical attention. in infection of the person. Flea and tick control should
Leptospira spp. can be transmitted in urine from infected always be maintained with animals, and infested animals
dogs and cats to humans, resulting in clinical disease (Sykes seen in the clinic should be treated immediately. See
et al., 2010). Host-adapted species cause subclinical infec- other sections of this textbook for detailed discussions of
tion; infection by non-host-adapted species commonly these agents.
results in clinical illness. The organisms enter the body
through abraded skin or intact mucous membranes. (See
Chapter 94 for a detailed discussion of the clinical manifesta- SHARED ENVIRONMENT ZOONOSES
tions of this disease and its treatment in dogs and cats.)
Human clinical syndromes vary with the serovar but are Some agents that infect both animals and man are not com-
similar to those that occur in the dog. Animals with sus- monly transmitted between the pet and the owner by direct
pected leptospirosis should be handled while wearing gloves. contact but are acquired from the same environmental
Contaminated surfaces should be cleaned with detergents source. Notable examples include Histoplasma capsulatum,
and disinfected with iodine-containing products. Vaccines Coccidioides immitis, Blastomyces dermatitidis, Cryptococcus
containing four leptospire serovars should be considered neoformans, and Aspergillus spp. See Chapter 97 for detailed
(see Chapter 93). discussions of these agents.
Brucella canis is a bacterium that preferentially infects
the testicles, prostate, uterus, and vagina of dogs (see Chap- Suggested Readings
ters 55 and 56). The infection is maintained in dogs pri- Biswas S, et al. Comparative activity of pradofloxacin, enrofloxacin,
marily by venereal transmission. Humans can be infected and azithromycin against Bartonella henselae isolates collected
from cats and a human. J Clin Microbiol. 2010;48:617.
by direct contact with vaginal and preputial discharges Bradbury CA, Lappin MR. Evaluation of topical application of
from dogs. Clinical syndromes in dogs are diverse but 10% imidacloprid-1% moxidectin to prevent Bartonella hense-
commonly include abortion, stillbirth, failure to conceive, lae transmission from cat fleas. J Am Vet Med Assoc. 2010;236:
orchitis, epididymitis, vaginal discharge, uveitis, discospon- 869.
dylitis, and bacteremia. Intermittent fever, depression, and Breitschwerdt EB, et al. Bartonellosis: an emerging infectious
malaise are common in infected people. Diagnosis is based disease of zoonotic importance to animals and human beings. J
on serologic testing or demonstration of the organism by Vet Emerg Crit Care (San Antonio). 2010;20:8.