European Journal of Obstetrics & Gynecology and Reproductive Biology
Pregnancy as a risk factor for acute toxoplasmosis seroconversion
Introduction
Toxoplasmosis is a zoonosis widely spread in nature, caused by a coccidian protozoan, Toxoplasma gondii. Its importance is due to the possibility of transplacental transmission, damaging the fetus [1].
In most areas of the world, 50–90% of the population carry antibodies against the parasite, demonstrating previous exposure. Some countries with low prevalence (<20%) are Thailand (3%), Japan, and USA. Australia (23%), UK (35%), Poland (36%), and Belgium (53%), show average prevalence. Tahiti (77%) and France present high prevalence (>60%) [2], [3], [4].
The rate of pregnancy damage depends on the infection prevalence among women at child-bearing age, among the animals they eat, the level of contact between vulnerable pregnant women and the sources of protozoan transmission, and on the time of gestation when the transmission occurs; the earlier in gestation transmission occurs, the greater the severity of sequelae in the fetus or newborn is [5].
In different geographical regions, annual seroconversion rates range from 0.6 to 1.5% [6], [7], [8]. The incidence of infection increases with age, and several studies have shown high prevalence among women at child-bearing age, although the children are more exposed to the sources of transmission of this parasite [3]. Some studies present conflicting results. A study by Walpole et al. [5], in Australia, could not relate exposure of women with seroconversion to any known risk factors. In the Netherlands, there was an inexplicable rise in infection rate at the end of pregnancy, despite the prophylactic measures adopted [5].
In pregnancy, there are alterations in the mother’s T-lymphocyte sub-populations, mainly at the end of pregnancy, with CD4 lymphocytes decreasing and CD8 lymphocytes increasing, and depletion of the function of NK cells as to the immune function of neutrophils, monocytes, and macrophages. The phagocytic function and the chemotaxis of polymorphonuclear neutrophils are depleted in women between the 30th and 34th weeks of gestation, thus justifying a higher vulnerability to the invasion of this micro-organism during the third trimester of pregnancy [10], [11], [12], [13]. The immune mechanisms, which are altered in pregnancy, are exactly the ones that protect her against T. gondii [1], [2], [3]. These immunological alterations could explain the higher vulnerability of pregnant women to the protozoan found in Australia [4] and the failure of prophylactic measures in the Netherlands [9].
Although there are many studies about the risk factors for seroconversion and its effects on pregnancy, no studies on the risk of pregnancy itself were found.
Section snippets
Methods
The study was carried out between January 1997 and 1999, in Goiânia (GO), a capital city in the midwestern region of Brazil.
Women of child-bearing age (12–49 years old) were identified via parental clinics, birth control groups, communitarian work groups, religious congregations, or public night elementary and high schools, and invited for meetings. Volunteers who consented to be followed for 6–12 months had blood samples collected, totalling 3564 women. The result of the serological screening
Results
Table 1 shows the percentage of women who were pregnant for the seroconverters and seronegative groups separately.
Table 2 shows the relation between low family income and low level of formal education, and seroconversion for different age groups.
In Table 3, we show the relation between various other factors and seroconversion, and in Table 4 the effect of pregnancy on these relationships.
In Table 5, we show the risk of seroconversion associated with environmental risk factors in pregnant and
Discussion
The prevalence of this infection varies in different regions of the world and even of the same city, which could be observed in Goiânia during the period of this study [11]. The north-western region of the city, where the population has lower family income, had already shown a statistical risk of seroconversion before the prevention program started. This city is located in the midwestern region of Brazil and presents tropical weather, which favours the survival of T. gondii oocysts, a fact that
Conclusion
The most important evidences found in this study were the identification of the adolescents as the group with the highest risk among the pregnant women, principally when they live in environments contaminated by host animals and vehicles of oocyst transmission, and the higher risk of acute infection for older pregnant women that consume contaminated food, such as raw meat, raw eggs and non-pasteurised goat’s milk. Daunter [19] showed that the presence of alterations in the balance
Acknowledgements
The authors would like to thank all the institutions and the people that have helped in the course of this research, collaborating in financial support, data collection, and sample processing. Financial support: National Foundation for Research Support; State Health Secretary of Goiás; Municipal Health Secretary of Goiânia; Technical laboratory support: Department of Parasitology, Institute of Tropical Pathology and Public Health, Federal University of Goiás; Laboratory of Immunology, Institute
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2017, Food ControlCitation Excerpt :Animal experiments have demonstrated an increased susceptibility to T. gondii infection in pregnant mice, possibly due to changes in immune function and hormone levels (Luft & Remington, 1982). Some epidemiological studies in humans have shown that pregnant women have a lower resistance to T. gondii (a higher risk of seroconverting) than nonpregnant women (Avelino, Campos, de Parada, & de Castro, 2004; Avelino, Campos, de Parada, & de Castro, 2003). Therefore, the use of an alternative scaling factor would give a more accurate estimate of annual new infection cases in pregnant women.
The progesterone level, leukocyte count and disgust sensitivity across the menstrual cycle
2016, Physiology and BehaviorCitation Excerpt :Those intricate local changes in the levels of immune factors may also affect systemic immune response to an infection, inducing a state of increased susceptibility to certain bacterial, viral or yeast pathogens. For instance, there is some evidence that gestation increases vulnerability to Mycobacterium leprae [19], Toxoplasma gondii [20], or Listeria monocytogenes [21] infection. What is more, influenza infection exhibits more severe symptoms, involves more complications and higher mortality rate in pregnant women [22–25].
Gestational toxoplasmosis in Paraná State, Brazil: Prevalence of IgG antibodies and associated risk factors
2013, Brazilian Journal of Infectious DiseasesCitation Excerpt :Regarding other factors studied such as raw fruit and/or vegetable ingestion, type of water consumed, presence of dogs, and presence of a vegetable garden in the residency were not significant either. However, the various studies carried out in Brazil and in the world have shown variation in these results, which can be explained by the climactic, cultural and hygiene differences of the various populations and also by the difference in methodologies employed in the studies, making it difficult to compare the results.11,12,27,28 Due to the low incidence of acute toxoplasmosis during pregnancy and the high cost of cohort studies, most of the studies that aim to determine toxoplasmosis risk factors are on prevalence and not on incidence.
Institutions associated with the research: Medical School of the Federal University of Goiás (FM-UFG), Institute of Tropical Pathology and Public Health of the Federal University of Goiás (IPTESP-UFG), National Foundation of Support to Research (FUNAPE), State Secretary of Health of Goiás, and Municipal Secretary of Health of Goiânia (GO). Study accomplished between January 1997 and 1999.