326 



SARCOCYSTIS, TOXOPLASMA AND RELATED PROTOZOA 



Geographic Distribution : Worldwide. 



Prevalence : Toxoplasmiasis is ap- 

 parently extremely common in man and 

 also in many domestic animals. As Jacobs 

 (1957) said, there is a sea of ToxoplasDia 

 infection around us. However, toxoplas- 

 mosis is far less common. Most infec- 

 tions are inapparent, and the disease itself 

 appears only under special circumstances, 

 many of which are still unknown. 



Most of the surveys which have been 

 made for Toxoplasuia have been serologic 

 and indicate either previous or present 

 infections. In some cases, particularly 

 in sheep and other domestic animals in 

 which Sarcucystis infection is common 

 and in which the Sabin-Feldman dye test 

 was used, they may indicate merely the 

 presence of cross-reacting antibodies 

 (Muhlpfordt, 1951; Awad, 1954; Awad and 

 Lainson, 1954). Hence surveys in which 

 the organism itself was isolated are more 

 reliable, altho much more time-consuming 

 and expensive. 



The prevalence of antibodies varies 

 widely in man in different geographic lo- 

 cations. For instance, according to 

 Jacobs (1957), there is relatively less in- 

 fection in California than in the eastern 

 United States. Feldman and Miller (1956a) 

 observed positive dye tests in 68% of 121 

 persons on Tahiti, 64% of 266 in Honduras, 

 36% of 104 in Haiti, 35% of 144 in Pitts- 

 burgh, Penn. , 31% of 270 in New Orleans, 

 26% of 184 in St. Louis, 17% of 293 in 

 Portland, Ore., 11% of 108 on Iceland, 

 4% of 236 Navajo Indians in Arizona, and 

 none of 21 Eskimos in Alaska. In a study 

 of 1072 urban and rural Negroes 11 to 19 

 years old in the region of Memphis, Ten- 

 nessee, Gibson (1956) found that the 

 Sabin-Feldman dye test was positive in 

 20. 4% of the urban and 18. 9% of the rural 

 group. Balozet (1955) found that 12% of 

 125 humans in Algiers were positive to 

 the complement fixation test. Thiermann 

 and Naquira (1958) found that the dye test 

 was positive in 43% and the complement 

 fixation test in 11% of 284 normal medical 

 students in Santiago, Chile; the dye test 

 was positive in 48% and the complement 

 fixation test in 2% of 131 blood donors, 

 mostly over 30 years old. Orio et al. 



(1958) found that the sera of 10. 2% of 1139 

 Africans in Middle Congo were positive 

 to the complement fixation test. The above 

 results give some idea of the range of pos- 

 itive reactions which may be expected in 

 different surveys. 



Among domestic animals, the first 

 spontaneous case of toxoplasmosis in the 

 dog was reported by Mello (1910) in Turin, 

 Italy. In reviewing the animal reservoir 

 of toxoplasmosis, Habegger (1953) stated 

 that only something more than 50 cases had 

 been reported in dogs thruout the world. 

 However, more recent reports have raised 

 this figure considerably. 



Miller and Feldman (1953) found dye 

 test antibodies in 59% of 51 dogs in Penn- 

 sylvania. Feldman and Miller (1956a) 

 found them in 28% of 51 dogs from New 

 York, 30% of 23 dogs from Arizona and 

 86% of 7 dogs from Honduras. Siim (1950) 

 found that 18. 5% of 54 dogs in Copenhagen 

 had dye test titers of 1:250 or more. Often, 

 Westphal and Kajahn (1950) found that 36% 

 of 84 dogs in Hamburg, Germany were 

 positive to the dye test. Borgen and Berg 

 (1957) found that 44.5% of 20 dogs in Norway 

 were positive to the dye test. De Roever- 

 Bonnet (1957) found that 1 of 75 dogs in 

 Amsterdam was positive to the dye test at 

 a titer above 1:100. Makstenieks and 

 Verlinde (1957) found that 14% of 29 dogs 

 from households in the Netherlands where 

 human toxoplasmosis existed were positive 

 to the dye test at 1:64 or above. Eyles 

 et al. (1959) found that 8. 3% of 809 dogs 

 from the Memphis pound or slums were 

 positive to the dye test at a titer of 1:64 

 or above, and they isolated Toxoplasma by 

 mouse inoculation from 3 of 200 of the 

 dogs. Gibson and Jumper (1960) found 

 that the sera of 16% of 800 dogs from the 

 Memphis pound were positive to the dye 

 test at a titer of 1:16 or above; they found 

 Toxoplasma by mouse inoculation in only 

 2 out of 75 of these animals. 



Morris, Aulisio and McCown (1956) 

 found that 25%i of 180 dogs in the Middle 

 Atlantic stages were positive to the com- 

 plement fixation test. Lainson (1956) 

 found that 42. 5% of 113 dogs in London 

 were positive to the complement fixation 

 test. Balozet (1955) found that 30% of 



