Thimerosal exposure & increasing trends of premature puberty in the vaccine safety datalink.

Background & objectives: The US Agency for Toxic Substances and Disease Registry (ATSDR) reports that mercury (Hg) is a known endocrine disruptor and it adversely affects the steroid synthesis pathway in animals and humans, and may interact to enhance the risk for a child developing premature puberty. An association between premature puberty and exposure to Hg from thimerosal-containing vaccines (TCVs) was evaluated in computerized medical records within the Vaccine Safety Datalink (VSD). Methods: A total of 278,624 subjects were identified in birth cohorts from 1990-1996. The birth cohort prevalence rates of medically diagnosed International Classification of Disease, 9th revision (ICD-9) premature puberty and control outcomes were calculated. Exposures to Hg from TCVs were calculated by birth cohort for specific exposure windows from birth-7 months and birth-13 months of age. Poisson regression analysis was used to model the association between the prevalence of outcomes and Hg doses from TCVs. Results: Significantly increased (P<0.0001) rate ratios were observed for premature puberty for a 100 μg difference in Hg exposure from TCVs in the birth-7 months (rate ratio=5.58) and birth-13 months (rate ratio=6.45) of age exposure windows. By contrast, none of the control outcomes had significantly increased rate ratios with Hg exposure from TCVs. Interpretation & conclusions: Routine childhood vaccination should be continued to help reduce the morbidity and mortality associated with infectious diseases, but efforts should be undertaken to remove Hg from vaccines. Additional studies should be done to evaluate the relationship between Hg exposure and premature puberty.

Comparative evaluation of phenol and thimerosal as preservatives for a candidate vaccine against American cutaneous leishmaniasis

For decades thimerosal has been used as a preservative in the candidate vaccine for cutaneous leishmaniasis, which was developed by Mayrink et al. The use of thimerosal in humans has been banned due to its mercury content. This study addresses the standardization of phenol as a new candidate vaccine preservative. We have found that the proteolytic activity was abolished when the test was conducted using the candidate vaccine added to merthiolate (MtVac) as well as to phenol (PhVac). The Montenegro's skin test conversion rates induced by MtVac and by PhVac was 68.06 percent and 85.9 percent, respectively, and these values were statistically significant (p < 0.05). The proliferative response of peripheral mononuclear blood cells shows that the stimulation index of mice immunized with both candidate vaccines was higher than the one in control animals (p < 0.05). The ability of the candidate vaccines to induce protection in C57BL/10 mice against a challenge with infective Leishmania amazonensis promastigotes was tested and the mice immunized with PhVac developed smaller lesions than the mice immunized with MtVac. Electrophoresis of phenol-preserved antigen revealed a number of proteins, which were better preserved in PhVac. These results do in fact encourage the use of phenol for preserving the immunogenic and biochemical properties of the candidate vaccine for cutaneous leishmaniasis.

Comparative evaluation of the merthiolate-iodine-formaldehyde concentration technique and the Kato-Katz technique in the quantitative diagnosis of schistosomiasis japonica

A total of 384 stool specimens found to be positive for schistosoma eggs using the Direct Fecal Smear were further examined quantitatively by the MIFC and the Kato-Katz techniques. MIFC has a higher efficiency rate (95.57%) as compared to Kato-Katz technique (73.43%). Kato-Katz yields a higher percentage of false negatives (26.56%). These found to be statistically significant. With regards to quantification, Kato-Katz has a higher mean egg difference (245.69%) but this was found to be statistically significant. Thus, MIFC technique is more reliable and efficient than Kato-Katz in the quantitative diagnosis of Schistosomiasis japonica. (Auth. Sum.)

Studies on schistosomiasis egg quantification in the stool: evaluation of the merthiolate-iodine-formaldehyde-concentration technique

The presentation consists of two main parts which deal on the evaluation of the Merthiolate-Iodine-Formaldehyde-Concentration (MIFC) technique of stool examination and the recommended improved method for schistosome egg counting. It is felt that studies along this line will be a practical value in the assessment of the efficacy of schistosomicidal drugs for so far, no drug against Schistosoma japonicum infection has been found to give a 100% cure rate within a span of six months follow-up. From the point of view of disease transmission, a good quantitative procedure for egg counts is likewise deemed important.(Auth. Abs.)