Background and Symptoms
Toxoplasma gondii is very wide-spread in nature, and infects virtually all mammalian
species.1 This obligate intracellular
protozoan was first discovered in gondis, a small cricetine
rodent, maintained at the Pasteur Institute of Tunis.2
Toxoplasmoisis remained an obscure disease of laboratory
rabbits and guinea pigs at the Pasteur institute in Paris until
1937, when it was identified as a cause of congenital meningoencephalitis in infants. The majority of Toxoplasma
infections are asymptomatic and undiagnosed, although a
clinically acute acquired infection is characterized by fever,
headache, swollen lymph nodes, or pneumonia, and often resembles
infectious mononucleosis.3 Pregnant patients
with acute infection can transmit the disease to the fetus
causing abortion, stillbirth or severe congenital abnormalities.
Serological surveys have shown that by the age of 50 the
prevalence of infection can range from 30-40% in adult
populations in some areas of the United States.4
Toxoplasmosis is usually transmitted to people in poorly
cooked or raw meat, or by exposure to Toxoplasma oocysts
in the feces of infected cats.5 Latent
infections may become active in immunocompromised individuals
and can cause neurologic or pulmonary disease.3
was declared a reportable disease in Florida in 1964. During the
next decade, six human cases were reported. The number of cases
averaged 10 per year from 1974-93, however, 44 cases were
reported in 1994 and 1995 (22 each year). An analysis of these
cases showed that most were black (64%) and male (57%), with a
median age of 36 (range 6 to 84 years). Cases occurred in 13
counties throughout the state, but 18 (41%) were reported by St.
Lucie County. The vast majority of the St. Lucie County cases
were black (89%), and evenly divided by sex, with a median age
of 36 (range 23-72 years). The presumed source of infection or
immune status of these cases was not recorded. The most
recent five-year figures (2000-2005) show an average of 18 cases
per year confirmed within the state of Florida.
While it has been assumed
that most cases result from exposure to Toxoplasma
oocysts from cats, serologic surveys have shown relatively high
prevalence of T. gondii antibodies in horses (18%),
armadillos (19%), raccoons (18%), black rats (13%) and opossums
1. Mahmoud, AAF, and Warren, KS,
Algorithims in the diagnosis and management of exotic diseases: XX
Toxoplasmosis. J. Inf.
Dis. 1977;135: 493-96.
2. Frenkel, JK, Pursuing
toxoplasma. J. Inf. Dis. 1970;122: 553-59.
3. Melvin, DM et al. Blood and
tissue parasites. In Diagnostic Procedures for Bacterial,
Mycotic and Parasitic Infections, Balows, A and Hausler, WJ, (eds)
Am. Pub. Hlth. Assn. 6th edition, 1981; pp.1117-52.
4. Welch, PC et al. Serologic
Diagnosis of Acute Lymphadenopathic Toxoplasmosis. J. Inf.
5. Stagno, S et al. An
outbreak of toxoplasmosis linked to cats. Pediatrics,
6. Riemann, HP, et al. A
survey for antibodies to Toxoplasma gondii in horses. Am.
J. Vet. Res. 1975;36: 1797-1800.
7. Burridge, MJ, et al.
Serologic Survey for Toxoplasma gondii in wild animals in
Florida. JAVMA, 1979;175: 964-67.