Table 4.
Summary of evidence by risk factor.
| Risk factor | Studies suggesting increased risk of vertical transmission | Studies suggesting no difference in risk of vertical transmission |
|---|---|---|
|
| ||
| Maternal age | Three studies found an increased risk among younger mothers (Kaplinski et al., 2015; Messenger et al., 2017; Torrico et al., 2004). | Ten studies found no significant difference in risk with maternal age (Basile et al., 2019; Bern et al., 2009; Bua et al., 2012; Cardoni et al., 2004; Danesi et al., 2020; García et al., 2008; Martin Suasnabar et al., 2018; Negrette et al., 2005; Rendell et al., 2015; Salas et al., 2007). |
| Maternal parity | One study found an increased risk in infants with a larger number of siblings (Chaparro and Genero, 2018). | Two studies found significant no difference in risk with maternal parity (Bern et al., 2009; Salas et al., 2007). |
| Parasite load and diagnostics | Several studies found an increased risk with parasite load (Bern et al., 2009; Brutus et al., 2010; Bua et al., 2012; Kaplinski et al., 2015; Rendell et al., 2015), positive parasitemia (Salas et al., 2007), positive PCR (Bern et al., 2009; Burgos et al., 2007; Murcia et al., 2017, 2013),* positive T. cruzi hemoculture (Alonso-Vega et al., 2005; Hermann et al., 2004), or positive xenodiagnoses during pregnancy (Martin Suasnabar et al., 2018). | One study found a non-significant trend for higher risk with parasitic load among one subpopulation and no difference in risk in another subpopulation (Buekens et al., 2018). |
| Parasite genetics | One study found apparent clustering of parasite sequences from congenital transmission cases in the TcII-TcV-TcVI cluster (Herrera et al., 2019).* | One study found no significant difference in risk with T. cruzi IId lineage (Burgos et al., 2007). |
| Infant genetics | One study found an increased risk with infant mutations in SNPs of the ADAM12 (rs11244787, rs1871054) and MMP2 (rs243866, rs17859821, rs2285053) genes, which code for placental expression enzyme (Juiz et al., 2016). | One study found no significant difference in risk with infant mutations in SNPs of the ALPP (rs2014683, rs1048988), MMP2 (rs243865, rs243864, rs2285053), and MMP9 (rs3919242, rs2234681) genes (Juiz et al., 2016). |
| Socioeconomic factors | Two studies found no significant difference in risk among women who lived in a rural area (Salas et al., 2007) or lived in a rural area during infancy (Chaparro and Genero, 2018). | |
| One study found no significant difference in risk among women based on home construction materials, education level, types of appliances owned, or living in a rural area (Kaplinski et al., 2015). | ||
| Twins | Two studies found higher risk in twin than singleton births (Kaplinski et al., 2015; Rendell et al., 2015). | One study found no significant difference in risk between twin and singleton births (Salas et al., 2007). |
| Siblings and families | One study found an increased risk with having other siblings with Chagas (Basile et al., 2019). | |
| One study found an increased risk among infants whose maternal grandmother was infected with T. cruzi (Danesi et al., 2020). It also found an increased risk among infants with siblings infected congenitally. | ||
| Immunologic factors | One study found an increased risk among infants with higher IL-17A, higher MCP-1, higher monokine induced by IFN-γ, and lower IFN-γ (Volta et al., 2016). | One study found no significant difference in risk by maternal IL-2, IL-4, IL-10, or TGF-β1 levels (Hermann et al., 2004). |
| One study found an increased risk among women whose cord blood had higher IFN-γ and lower IL-10 (Alonso-Vega et al., 2005).* | One study found no significant difference in risk by maternal IL-10 or IFN-γ levels (Cardoni et al., 2004). | |
| One study found increased risk among women with higher IFN-γ in whole blood cells incubated with T. cruzi lysate and women with lower proportions of CD4+ HLA-DR+ T lymphocytes (Hermann et al., 2004). | One study found no significant difference in risk by blood leukocyte count, percentage of monocytes, levels of sTNF-R2, or levels of IL-10 (García et al., 2008). | |
| One study found an increased risk among mothers with lower TNF-α levels (Cardoni et al., 2004).* | One study found no significant difference in risk by infant levels of IL-10 or sTNF-R1 (García et al., 2008). | |
| One study found an increased risk among mothers with lower TNF and sTNF-R1 (García et al., 2008). | ||
| One study found an increased risk among infants with lower levels of TNF at 1 month or higher levels of sTNF-R2 at 1 and 12 months (García et al., 2008). | ||
| Maternal HIV status | One study found an increased risk among women with HIV (Scapellato et al., 2009). | |
| Vector exposure | Two studies found a higher risk among women who had never lived in a triatomine-infested house than women who had (Kaplinski et al., 2015; Rendell et al., 2015). | Three studies found no significant difference in risk between women who reported currently having triatomine bugs in the home and women who did not (Chaparro and Genero, 2018; Kaplinski et al., 2015; Rendell et al., 2015). |
| One study found a higher risk among women with low or no vector exposure than women with medium or high vector exposure (Martin Suasnabar et al., 2018). | ||
| One study found a higher risk among women from endemic areas with high vector control than women from endemic areas with low vector control (Negrette et al., 2005). | ||
| One study found a higher risk among women from areas of low vectorial risk than high vectorial risk (Danesi et al., 2020). | ||
| Infant sex | One study found an increased risk among female infants (Messenger et al., 2017). | Two studies found that infant sex was not a significant risk factor (Negrette et al., 2005; Salas et al., 2007; Torrico et al., 2004). |
| Other | One study found increased risk with the maternal cardiac form of Chagas disease, compared to the indeterminate form (Basile et al., 2019). | Two studies found that maternal history of blood transfusion was not a significant risk factor (Chaparro and Genero, 2018; Martin Suasnabar et al., 2018). |
| One study found that sibling order was not a risk factor (Negrette et al., 2005). | ||
| One study found no significant difference in risk by maternal hemoglobin or hematocrit levels (Torrico et al., 2006).* | ||
*
Statistics not provided in the original study for this association