Officials from the Centers for Disease Control and Prevention (CDC) have declared that Zika virus is a teratogen that causes microcephaly and other serious brain anomalies. That conclusion was announced in a special report in The New England Journal of Medicine which outlined the investigator’s systematic analysis of epidemiologic evidence on the virus to date.
The goal of the effort by CDC researchers was to determine whether cause and effect could be established between prenatal Zika virus and subsequent birth defects. The data on Zika virus were evaluated against the criteria proposed by Shepard in 1994 as a “yardstick” for establishing human teratogenicity.
The 4 key criteria of Shepard’s that the Zika virus has met, said the CDC authors, and which justify the new classification, are as follows:
· Exposure to Zika virus occurs at a critical time in prenatal development, as documented in a report of laboratory-confirmed transmission in specific areas of Brazil and an increase in the number of cases of microcephaly identified in the first trimester;
· Clinical cases with the teratogenic effect have been clearly delineated, as seen in what the authors described as descriptions of the typical pattern of findings in Zika-exposed fetuses and infants, such as severe microcephaly, intracranial calcifications, and other brain abnormalities; and
· Verification that the association involves a rare exposure and a rare defect, as supported by evidence indicating that microcephaly is rare in the United States, with an incidence of 6 per 10,000 live births, and that adverse birth outcomes have been seen in offspring of women who spent only a limited period of time in an area where Zika virus was endemic.
With Zika virus confirmed as teratogenic, the CDC authors said, the focus of research can now shift to “understanding the full spectrum of defects caused by congenital Zika virus infection; if Zika virus is similar to other teratogens…, quantifying the relative and absolute risks among infants who are born to women who were infected at different times during pregnancy…and identifying factors that modify the risk of an adverse pregnancy or birth outcome.”
Is HPV vaccination effective in girls with kidney disease?
The quadrivalent human papillomavirus (HPV) vaccine may be as effective in girls with chronic kidney disease as in those without kidney disease, according to a new small study in the Clinical Journal of the American Society of Nephrology. However, the effectiveness may not carry over to girls who have had a kidney transplant.
The researchers performed a cohort study from 2008 to 2012 with 57 girls aged 9 to 21 years who had chronic kidney disease (n = 25), were in dialysis (n = 9), or who were post-kidney transplantation (n = 23) and had received the standard 3-dose HPV vaccine series. The girls were recruited from 2 pediatric nephrology clinics. The girls’ antibody levels of HPV genotypes 6, 11, 16, and 18 were assessed before vaccine dose 1 (baseline), <12 months after vaccine dose 3 (blood draw 2), and ≥12 months after vaccine dose 3 (blood draw 3). Some of the participants did not complete all 3 blood draws.
The antibody response to all 4 of the HPV genotypes was 100% in the chronic kidney disease and dialysis groups according the second and third blood draws. However, far fewer girls who had undergone transplants achieved seropositivity at blood draw 2 for HPV genotypes 6 (63.6%; P=0.003), 11 (63.6%; P=0.003), and 18 (72.7%; P=0.02) and at blood draw 3 for HPV genotypes 6 (62.5%; P=0.02), 11 (50%; P=0.001), 16 (75%; P=0.04), and 18 (50%; P=0.001).
The authors concluded that the antibody response to the quadrivalent HPV vaccine was strong and sustained in females who either had chronic kidney disease or were on dialysis. A similarly strong response was not seen among the participants who had undergone kidney transplant. They urged further study to find out if vaccination before kidney transplantation or a different vaccination regimen would benefit kidney transplant recipients.
Does cannabis use lead to adverse pregnancy outcomes?
Women who use cannabis during the course of their pregnancy may be more likely to deliver infants with low birthweight who need intensive care, according to a recent meta-analysis published in BMJ Open.
Researchers used 7 electronic databases, which were searched from inception to April 2014 for case-control, cross-sectional, and cohort studies that investigated cannabis use during pregnancy and the subsequent maternal and fetal outcomes. Maternal, fetal, and neonatal outcomes covering up to 6 weeks postpartum after exposure to cannabis were studied.
Variables that had 3 or more studies where the outcomes were consistently measured were used. Outcomes included in the meta-analysis were anemia, birthweight, low birthweight, neonatal length, placement in the neonatal intensive care unit, gestational age, head circumference, and preterm birth.
Overall, the investigators used 24 studies in their review. Analysis showed that women who used cannabis during pregnancy had increased odds of anemia (pooled OR [pOR]=1.36: 95% CI 1.10 to 1.69) when compared to women who did not use cannabis during pregnancy. When compared to infants with no in utero exposure to cannabis, those with exposure had a decrease in birth weight (low birth weight pOR=1.77: 95% CI 1.04 to 3.01; pooled mean difference (pMD) for birth weight=109.42â g: 38.72 to 180.12). In addition, infants with exposure to cannabis in utero were found to be more likely to be placed in the neonatal intensive care unit (pOR=2.02: 1.27 to 3.21).
The researchers concluded that cannabis use during pregnancy could lead to adverse outcomes in both mother and baby. Due to the increasing social acceptance of cannabis use, they stated that both healthcare providers and expectant mothers could use more education on the potential adverse effects of cannabis during pregnancy.