Fig 1.
Geographic distribution of opossum sampling sites.
(A) Map of Mexico, with the state of Yucatan (shaded area). (B) Map of the state of Yucatan. The gray area highlights the metropolitan area of Merida where opossum sampling was conducted. (C) Sampling sites within the metropolitan area of Merida. Red dots indicate urban setting locations where opossums tested positive for T. cruzi, while black dots indicate urban setting locations where opossums tested negative. The map was generated using RStudio (version 2023.06.1), integrating geolocation data collected during the study along with publicly accessible municipal boundary data for Yucatan, Mexico, obtained from INEGI (https://www.inegi.org.mx/app/biblioteca/ficha.html?upc=889463770541), and used in compliance with the “Terms of Free Use of INEGI Information” (https://www.inegi.org.mx/inegi/terminos.html).
Fig 2.
Procedures for sample collection from opossums.
(A) Blood sampling: Blood was collected by venipuncture of the caudal vein. The image shows a D. virginiana female immobilized by physical restraint while blood sampling is performed. Several offspring are visible emerging from the marsupium. (B) Anal gland secretion sampling: Anal gland secretions were collected through manual compression. The image captures the posterior region of the opossum with the anal gland being compressed and the secretions collected in a tube. (C) Milk sampling: Milk was collected by gently expressing the mammary gland into a sterile collection tube. The image depicts the mammary gland being gently compressed to obtain the sample.
Table 1.
Prevalence of T. cruzi DNA in different samples obtained from male and female D. virginiana.
Fig 3.
Parasite load by sex and reproductive condition in Didelphis virginiana: This boxplot illustrates the distribution of T. cruzi parasite loads (expressed as parasite DNA equivalent per mL of blood) across different groups: females with offspring, females without offspring, and males.
Each individual parasite load of opossum is depicted by a dot. The boxes represent the interquartile range (IQR), with the line inside indicating the median. The whiskers extend to the minimum and maximum values. The boxes for females (both with and without offspring) are shaded gray, whereas the box for males is white. The females with offspring had the lowest median parasite load, followed by females without offspring, while males exhibited the highest median parasite load. No statistical difference was found using the Kruskal-Wallis test (p-value = 0.067).