Clotting-factor concentrates (CFC) are a potential source of transmission of blood-borne viruses. Newer physical and chemical methods (pasteurization, wet-heating, solvent/detergent treating) developed to inactivate viruses are effective against HIV, HBV and HCV. However, it is not clear if these methods protect against other pathogenic viruses such as parvovirus B19, cytomegalovirus (CMV), hepatitis A virus (HAV) and hepatitis E virus (HEV). To evaluate the safety of current CFC we have studied seroprevalence of parovirus B19, CMV, HAV and HEV antibodies in 22 HIV and HCV negative haemophiliacs who were treated exclusively with clotting-factor concentrates considered safe with respect to HIV and HCV transmission, 22 healthy individuals served as controls. Neither HAV nor HEV antibodies were detected in haemophiliacs or controls. Two controls and two haemophiliacs were seropositive for CMV. Five controls (32% prevalence) and 15 haemophiliacs (77%) were positive to parovirus B19. No statistical differences can be established for seropositivity with CMV, HAV and HEV between haemophilic patients and controls. In the case of parvovirus B19 the differences are statistically significant (P= 0.0128). The relative risk of parvovirus B19 is 2.4 in the case of haemophiliacs. CFC considered safe against HIV and HCV are not safe against parvovirus B19, although they seem to be safe against CMV, HAV and HEV.
To evaluate the influence of the dose of co-trimoxazole prophylaxis on the risk of toxoplasmosis in human immunodeficiency virus (HIV)-infected patients, we performed a nested case-control study of 32 patients with toxoplasmosis (case patients) and 64 patients without toxoplasmosis (control patients) who were matched by CD4 cell count and Toxoplasma gondii serostatus; these patients were from a cohort of 521 HIV-infected patients who underwent a diagnostic neuroimaging study between March 1993 and January 1997. Twenty-seven (84.4%) of 32 case patients and 33 (51.6%) of 64 control patients received low doses of co-trimoxazole, a finding associated with an adjusted odds ratio (OR) of 9.36 (95% confidence interval [CI], 2.05-42.75) and indicating 89% protective efficacy for high doses. Fifteen (46.9%) of 32 case patients and 16 (25%) of 64 control patients were exposed to rifampin (adjusted OR, 3.38; 95% CI, 1.08-10.61). These results indicate that high doses of co-trimoxazole appear to be more effective than low doses for lowering the risk of toxoplasmosis in HIV-infected patients and that rifampin therapy may reduce the efficacy of co-trimoxazole.
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