ABSTRACT
Low levels of antibodies to N. caninum have been reported in human sera (Table 13.1). The significance of these findings is uncertain because neither parasite DNA nor the parasite has been confirmed in human tissues. Nevertheless, N. caninum has been successfully cultured in human cell lines such as MCF-7 human breast carcinoma, 1237 human brain microvascular endothelial cells (HBMECs), 648 human trophoblast (BeWo) and uterine cervical (HeLa), 310 human foreskin fibroblasts (HFFs), human astrocytoma cell line (86HG39), human epithelial lung cells (A549 cells) 1885 and also, the same level of growth was observed when human serum instead of fetal bovine serum was used for tissue culture. 1512 Seroprevalence of <italic>N. caninum</italic> in Humans Country Source of Sample No. of Sera No. Positive % Positive Test (Cut-Off) a Remarks Reference Brazil HIV-infected patients 61 23 37.7 IFAT a (1:50), ELISA IH, IB using 29-kDa protein 5 samples were positive by IB 1198 Neurological disorders 50 9 18.0 8 samples were positive by IB Newborns 91 5 5.5 4 samples were positive by IB Control 54 3 5.6 2 samples were positive by IB HIV-infected patients 342 91 26.6 IFAT (1:50) 1 patient with 1:400 1531 Healthy farmers 67 7 10.5 IFAT (1:200) All 7 were positive by IB 192 Denmark Repeated miscarriage 76 0 0.0 ELISA (ISCOM), IFAT (1:640), IB No evidence of infection by N. caninum 1601 Egypt Pregnant 101 8 7.9 ELISA IH, NcSAG1t Results confirmed by IFAT, 1:100 967 France Healthy women 500 0 0.0 IFAT (1:80) No evidence of infection by N. caninum 1720 HIV patients 400 4 1.0 IFAT (1:80) 3 positive at 1:80, and 1 positive at 1:160 Korea Blood donors 172 Toxoplasma-positive sera 12 6.9 ELISA IH, IFAT (1:100) Some sera reacted to N. caninum in IFAT and WB 1449 110 Toxoplasma-negative sera 1 0.9 UK Blood donors 199-general population 0 0.0 IFAT (1:160) No evidence of infection by N. caninum 805 48-farm workers 0 0.0 Farm workers and women with miscarriage 400 0 0.0 IFAT (1:400) Titer <1:200 in 2 individuals. No evidence of infection by N. caninum 1993 Submitted to public health laboratories 3232 general population 0 0.0 ELISA IH, IFAT (1:50) No evidence of infection by N. caninum 1318 518 farm workers 0 0.0 USA Blood donors 1029 69 6.7 IFAT, (1:100), 35 kDa fraction in IB All samples were negative at 1:200 IFAT. 16 IFAT positive sera reacted in IB. 27.5% of positive cases were also positive for T. gondii infection 1987
ISCOM = Detergent extracted tachyzoite antigen incorporated in immune stimulating complex particles.
