Besnoitiawallacei (Tadros and Laarman, 1976) Dubey, 1977

ETYMOLOGY:Besnoitia (for Dr. C. Besnoit) wallacei (for Dr. G. Wallace)

SYNONYMS:Isospora wallacei Tadros and Laarman, 1976


GEOGRAPHIC DISTRIBUTION AND PREVALENCE: The prevalence of this parasite in cats is unknown. It has been reported from a naturally infected cats from Oahu, Hawaii (Wallace and Frenkel, 1975), Palmerston North, New Zealand and Kenya (Ng'ang'a et al., 1994). It has also been isolated from a cat fed naturally infected rats (Rattusrattus, R. norvegicus) collected near Launceston in Australia (Mason, 1980).

PARASITE IDENTIFICATION: Oocysts measure 16-19 by 10-13 by m (mean, 17 by 12 m). No micropyle or polar granule are present. Two elliptical sporocysts are present. Sporocysts measure 11-11 by 7-8 m (mean, 11 by 8 m) and do not contain Stieda bodies. Four sporozoites are present in each sporocyst and they measure approximately 2 by 10 m.

LIFE CYCLE: Only tissue cysts containing bradyzoites are infectious for cats (Wallace and Frenkel, 1975). The prepatent period is 12 to 15 days and the patent period is 5 to 12 days. Only one asexual generation has been described and it occurs in the lamina propria of the small intestine (Frenkel, 1977). The meronts measure between 500 and 800 m and are found 4 to 13 days after infection. Some meronts can be found in extraintestinal tissues. Sexual stages are goblet cells in the small intestinal epithelium. Macrogamonts are 16 to 13 m and microgamonts are about 11 m. Tissue cysts do not form in the tissues of cats.

Grossly visible tissue cysts, up to 200 m in diameter, are present in the tissues of mice 30 to 6 days after they are fed oocysts. The tissue cyst wall is up to 30 m thick and contains numerous hypertrophic host cell nuclei.


CLINICAL PRESENTATION AND PATHOGENESIS: Clinical signs of infection in cats have not been reported.

TREATMENT:Besnoitia wallacei infection does not cause clinical disease in cats and no treatment is needed.


Frenkel JK. 1977. Besnoitia wallacei of cats and rodents: with a reclassification of

other cyst-forming isosporoid coccidia. J Parasitol 63:611-628.

Mason RW. 1980. The discovery of Besnoitiawallacei in Australia and the identification of

a free-living intermediate host. Z. Parasitenkd. 61: 173-178.

Ng'ang'a CJ, Kanyari PW, Munyua WK. 1994. Isolation of Besnoitia wallacei in Kenya.

Vet Parasitol 52:203-206.

Wallace GD, Frenkel JK. 1975. Besnoitia species (Protozoa, Sporozoa, Toxoplasmatidae):

recognition of cyclic transmission by cats. Science 188:369-371.