Isospora natalensis Elsdon-Dew,
Type host: Homo sapien Linneaus, 1758,
Other hosts: None reported to date.
Type locality: AFRICA: South Africa,
Geographic distribution: AFRICA: South Africa,
Description of oocyst: Oocyst shape: spheroid to
subspheroid; number of
walls: 1 (in line drawing); wall characteristics: smooth, thin; L x W: 25-30 x
21-24; M: absent; OR: absent; PG: absent. Distinctive features of oocyst:
subspheroidal shape distinguishes it from I. belli.
Description of sporocysts and sporozoites:
Sporocyst shape: ellipsoid; L x
W: 17 x 12; L/W ratio: 1.4; SB: absent; SSB: absent; PSB absent; SR: present; SR
characteristics: large, coarse granules loose and irregularly distributed in
sporocyst and without limiting membrane; SP: "smaller than one would expect" without
RB or N visible. Distinctive features of the sporocyst: "they take up an equatorial
position in the oocyst."
Prevalence: Found in 2 individuals in Durban, South
Africa, but the sample size was not stated.
Sporulation: Exogenous. Oocysts sporulated in 24
left "in the
open," but in a closed container, development did not take place in 7 days. However,
when the container was reopened, "maturation took place as usual (Elsdon-Dew,
Prepatent period: Unknown.
Patent period: 4 days in 1 individual in whom the
oocysts were produced in
large numbers (Dodds and Elsdon-Dew, 1955).
Site of infection: Unknown. Oocysts recovered from
Material deposited: None.
Remarks: This species has not been reported since
Its oocysts resemble those of the I. ohioensis complex in dogs, I.
rivolta in cats,
and I. suis in pigs, but they are slightly larger than these species (Lindsay
al., 1997). The oocysts also closely resemble those of I. arctopitheci in
every mensural and qualitative way (cf. Figs. 14, 20). Given the unusually broad
host range of I. arctopitheci, it may be the same species and, thus, would be
References: Dodds and Elsdon-Dew (1955); Elsdon-Dew
(1953); Lindsay et al. (1997).