Building Programs to Eradicate Toxoplasmosis Part III: Epidemiology and Risk Factors

Abstract

Purpose of review: Review comprehensive data on rates of toxoplasmosis in Panama and Colombia.

Recent findings: Samples and data sets from Panama and Colombia, that facilitated estimates regarding seroprevalence of antibodies to Toxoplasma and risk factors, were reviewed.

Summary: Screening maps, seroprevalence maps, and risk factor mathematical models were devised based on these data. Studies in Ciudad de Panamá estimated seroprevalence at between 22 and 44%. Consistent relationships were found between higher prevalence rates and factors such as poverty and proximity to water sources. Prenatal screening rates for anti-Toxoplasma antibodies were variable, despite existence of a screening law. Heat maps showed a correlation between proximity to bodies of water and overall Toxoplasma seroprevalence. Spatial epidemiological maps and mathematical models identify specific regions that could most benefit from comprehensive, preventive healthcare campaigns related to congenital toxoplasmosis and Toxoplasma infection.

Keywords: Incidence; Prevalence; Risk factors; Screening; Spatial epidemiology; Toxoplasma; Toxoplasmosis.

Fig. 1

Sample slides from presentation by Pandey, Moreira, Wang, Rzhetsky, McLeod et al. that details their studies in Panama. One component of their research was a study on the effectiveness of using digital media to teach pregnant women about congenital toxoplasmosis. Pandey and Moreira also created incidence and screening maps for toxoplasmosis in Panama; these maps were based on screening data, IgG/IgM test results, demographic data, and addresses from prenatal control charts. See Supplement for complete presentation

Fig. 2

Dot and scatter hexbin maps based on Moreira and Pandey et al.’s data on relative screening frequencies of patients in the Ciudad de Panamá metropolitan region. In the top two maps, gray points represent patients not screened for toxoplasmosis, orange points represent patients positive for infection, and blue points represent seronegative patients. Across all four maps, major trends in screening and case frequency include higher frequency of screening from north (more rural) to south (more urban) and higher seropositivity rates along roads and waterways

Fig. 3

Maps of screening rates for CT by corregimiento (township) at three different scales, based on Wang et al.’s findings and Moreira and Pandey et al.’s data. Screening rates were calculated using a Bayesian prior of Beta(254, 411). Average screening rate among the townships represented by the women with available data was 38.2%. Townships with much lower or higher than average screening rates are marked with white asterisks

Fig. 4

Summary of maps from Figs. 2 and 3, along with a map of toxoplasma seroprevalence by corregimiento (township) at three different scales. Prevalence rates were calculated using a Bayesian prior of Beta(63, 191). Average prevalence of toxoplasmosis among the townships represented by the women with available data was 24.8%. The highest rates of toxoplasmosis were observed in three provinces, shown in very dark red in the highest-resolution map, from west to east: Curundú, Pueblo Nuevo, Pedregal

Fig. 5

Summary of findings from Moossazadeh’s study of risk factors and development of a mathematical model for predicting highest-risk areas of Toxoplasma infection in Panama A A strong, but not significant, inverse relationship between highest level attained and screening compliance was found. B Rural-urban comparison showed that pregnant women in urban areas were more likely to be screened; the relationship was not significant. C Ages of IgM + women show that average age of educational; IgM positive women in both 2016–2017 studies was lower than the mean age of their cohorts (25.57 ± 9.03 cf. 27.28 ± 6.23 and 24.43 ± 7.24 cf. 26.59 ± 7.15, respectively). D T. gondii IgG seropositivity rates among pregnant women by maternal age, plotted with age centered around the mean. The curve represents the fit from the logistic regression of IgG status against age squared, with age centered around its mean. The points are shaded according to the number of women at each age, where darker colors signify a greater number of women. E Average education level among pregnant women by maternal age, plotted with age centered around the mean. F T. gondii IgG seropositivity rates among pregnant women by education level. Error bars represent the standard error of the mean. G T. gondii IgG seropositivity rates among pregnant women by longitude. Zero degree represents the longitude of Hospital Santo Tomás. H IgG seropositivity rate based on contact or no contact with dogs (both in the street or as pets). Error bars represent the standard error of the mean

Fig. 6

Summary of Raggi’s spatial epidemiological study of toxoplasma screening and seroprevalence rates in Panama. A KDE of previously screened individuals in the province of Panamá (n = 88). B KDE of previously unscreened individuals in the province of Panamá (n = 190). C KDE of previously screened individuals in Panamá Oeste (n = 60). D KDE of previously unscreened individuals in Panamá Oeste (n = 70). E KDE of positive IgG points in the province of Panamá (n = 83). F Aggregated toxoplasmosis prevalence rates based on Panama’s corregimientos, overlaid on Panama’s water systems

Fig. 7

Summary of mapping studies from Colombia. A Scatterplot matrix of all variables used in the Armenia study. B Statistically significant variable relationships and their p value ranges for the entire population surveyed. C Heat map showing the distribution of all cases of CT that went untreated in Quindío (n = 23). D Heat map showing cases of CT that received prenatal treatment in Quindío (n = 21). E Heat map of relative frequencies of cats negative for Toxoplasma, as determined by the University of Quindío (n = 109). F Heat map of relative frequency of cats positive for Toxoplasma, as determined by the University of Quindío (n = 25)