As part of our research on infectious
agents as possible causes of schizophrneia and bipolar disorder
(manic-depressive illness), the Stanley Laboraratory for Developmental
Neurovirology is also researching how such infectious agents could theoretically
be transmitted to humans. Cats are being investigated as one possible
reservoir for infections. It should be stressed that at this time we
have no proof that cats are involved in causing these diseases, and we are not
advocating that anyone avoid contact with their cats or otherwise change their
behavior toward cats. We are merely exploring the possibility as one
line of research with the goal of developing new methods for disease prevention
Why even consider cats at all?
There are several reasons to do so:
1. Cats carry at least 30
infectious agents which are known to be transmitted to humans. The
best known of these are rabies, the bacteria which causes cat scratch disease,
and toxoplasmosis. Some pediatric cancer specialists also suspect that some
childhood leukemias may be associated with a virus carried by cats but this has
not been proven.
2. Areas of the world in which
cats are very common (e.g. Ireland, Scandinavia) have a comparatively high
prevalence of schizophrenia and areas in which cats are not common (e.g. Papua
New Guinea) have a comparatively low prevalence.
3. Cats being widely kept as
housepets is a comparatively recent phenomena, starting in the early-mid 19th
century in England and North America. The increased prevalence of cats as
housepets coincides temporally with the increased prevalence of schizophrenia
and bipolar disorder according to one analysis (see E.F. Torrey and J. Miller, The
Invisible Plague: Rising Mental Illness from 1750 to the Present,
Rutgers University Press, to be published late 2001).
4. Two studies have reported that
individuals with schizophrenia and manic-depressive illness, compared to
individuals who do not have these disorders, have had greater exposure to cats
5. Some studies have reported
that individuals with first-onset schizophrenia have an increase in antibodies
6. There are case reports in the
literature of psychiatric and behavioral abnormalities in some individuals with
7. Some of the medications used
for the treatment of schizophrenia have the ability to inhibit toxoplasma in
Relevant articles, abstracts and
presentations at scientific meetings are linked below.
From House Cats? E. Fuller Torrey and Robert H. Yolken, Schizophrenia
Antecedents of Psychoses: A Case-Control Study of Selected Risk Factors
E. Fuller Torrey, R. Rawlings, R.H. Yolken, Schizophrenia Research, 2000.
to Toxoplasma Gondii in Individuals With First-Episode Schizophenia.
RH Yolken, S. Bachmann, I Ruslanova, E Lillehoj, G Ford, EF Torrey, Clinical
Infectious Diseases, 2001
Control Study of Schizophrenia and Affective Disorders and Toxoplasma Infection.
L Qiuying, L Xiaonian, L Li, et al. Acta Academiae Medicinae Hubei,
1999. (TABLES ONLY AT THIS TIME)
PRESENTATIONS AT SCIENTIFIC MEETINGS
Epidemiology of Severe Psychiatric Disorders: Is It Time To Put The Cat Out?
E. Fuller Torrey M.D., Stanley Foundation Research Program
Systematics of Toxoplasma gondii and Related Coccidia: Expanding the
Range of Distinguishing Characters for Taxonomy, Systematics and
John R. Barta, Department of Pathobiology, University of Guelph, Guelph,
INFECTION AND BEHAVIOURAL CHANGES–ANIMAL MODEL. Rick Holliman, St.
George’s Hospital and Medical School, London, UK
PATHOGENESIS OF TOXOPLASMOSIS. Vernon B. Carruthers, Johns Hopkins
University School of Public Health, Baltimore, Maryland
INFLUENCE OF LATENT TOXOPLASMOSIS ON HUMAN PERSONALITY. Jaroslav
Flegr, Department of Parasitology, Charles University, Prague, Czech Republic
EPISODES OF SCHIZOPHRENIA. John Gilmore , University of North Carolina at
Chapel Hill, Chapel Hill, NC
ARTICLES IN GENERAL INTEREST PERIODICALS