Maternal infections are associated with Intellectual Disability/Mental Retardation (ID/MR) in children.1 2 What began as a broad analysis of maternal genitourinary infections and pregnancy/child outcomes soon led to the discovery that Trichomoniasis also has a statistically significant association with intellectual disability.3 The main points of the study were as follows:

  • 134,596 mother-child pairs were examined.
  • Trichomonas was diagnosed in 3% of the women during pregnancy.
  • Other infections (chlamydia, gonorrhea, UTI or candidiasis) were diagnosed in 22%.
  • ID/MR was subsequently diagnosed in 4% of the children.

Consistent with prior studies, women with a genitourinary infection were significantly more likely to have a child with ID/MR (hazard ratio* or HR of 1.19.) Trichomonas infection alone, without another infection, was significantly associated with the development of intellectual disability. When analysis was focused on children with moderate to severe ID (i.e. excluding ‘mild ID’) the hazard ratio of trichomoniasis increased significantly to 1.83. (For comparison, alcohol has a hazard ratio of 1.18 relating to intellectual disability.) The bottom line; Trichomonas infection is significantly associated with the develop- ment of mental retardation, particularly so for moderate to severe forms. There are two caveats to these very important findings, which is that oral metronidazole treatment did not seem to affect the risk for ID/MR. (However, the authors recognized that they used the suboptimal source of outpatient pharmacy billing data to ascertain treatment and additional research, using more appropriate data sources, is needed to evaluate the effects of treatment of trichomoniasis on the risk of ID.) Also, one study showed a link between treatment with metronidazole and risk for preterm delivery.4 However, this study had important limitations, and in short, well defined conclusions regarding causation between metronidazole and preterm delivery cannot be made from this study and further research is also required in this area. Despite the above qualifications, this study has important implications. Trichomonas is often underestimated as an STD, both in terms of morbidity and incidence. However, recent findings suggest otherwise (see additional article in this issue.) Behavioral interventions and routine screening of the reproductive age population have the ability to reduce the prevalence of trichomoniasis in women. If future studies confirm these exploratory findings, more stringent health and screening efforts may be necessary.

Several Trichomonas organisms with squamous cell (bottom right) for scale; note the pear shape of the protozoan, with a central ovoid nucleus.

Several Trichomonas organisms with squamous cell (bottom right) for scale; note the pear shape of the protozoan, with  a central ovoid nucleus.

BIBLIOGRAPHY 1 Maternal infection and adverse fetal and neonatal outcomes. Goldenberg RL, Culhane JF, Johnson DC. 2005, Clin Perinatol., pp. 523-529. 2 Urinary tract infections during pregnancy and mental retardation and developmental delay. McDermott S, Callaghan W, Szwejbka L, Mann H, Daguise V. 2000, Obstet Gyne- col., pp. 113-119. 3 Trichomoniasis in Pregnancy and Mental Retardation in Children. Mann JR, McDermott S, Barnes TL, Hardin J, Bao H, Zhou L. 2009, Ann Epidemiol, pp. 891-899. 4 Failure of metronidazole to prevent preterm delivery among pregnant women with asymptomatic Trichomonas vaginalis infection. Klebanoff MA, Carey JC, Hauth JC, Hillier SL, Nugent RP, Thom EA et al. s.l. : N Engl J Med, 2001, Clin Microbiol Rev., pp. 37-45. REFERENCES: Available upon request