Prevalence of asymptomatic Leishmania infection and knowledge, perceptions, and practices in blood donors in mainland Portugal

BACKGROUND

Asymptomatic infection is the most common outcome of exposure to Leishmania parasites. In the Mediterranean region, where Leishmania infantum is endemic, studies on the prevalence of asymptomatic infection have often relied on serological testing in blood donors. In Spain, regional studies have shown seroprevalence in blood donors between 1 and 8%; in Portugal, values of 0 and 2% were suggested by two localized studies, in different populations. The purpose of this study was (i) to estimate the prevalence of asymptomatic Leishmania infection in blood donors in mainland Portugal, and (ii) to study the association between the detection of antibodies to Leishmania and sociodemographic factors, and also the knowledge, perceptions and practices (KPP) of the blood donors regarding leishmaniasis.

METHODS

A cross-sectional study targeted the population of people who donated blood in mainland Portugal. Participants, distributed proportionally by municipality and aged between 18 and 65 years, were selected randomly in 347 blood collection points between February and June 2022, and completed a sociodemographic and a KPP questionnaire. Detection of anti-Leishmania antibodies in serum was performed using an ELISA commercial kit. Individual KPP scores were calculated by adding grades defined for each question.

RESULTS

Globally, 201/3763 samples were positive. The estimated national true seroprevalence was 4.8% (95% CI 4.1-5.5%). The proportion of positive results was significantly different between NUTS (Nomenclature of Territorial Units for Statistics) regions. Models suggested that seropositivity was significantly higher in male sex, people older than 25 years, or residing in the Centro NUTS2 region, but not in dog owners nor people with lower KPP scores. Overall, 72.3% of participants had previously heard of leishmaniasis and, in multivariate analysis, a higher Knowledge score was associated with age 25-40 years, female sex, ownership of dogs, and higher education.

CONCLUSIONS

Global estimated true seroprevalence (4.8%) was similar to previous regional studies in blood donors in neighboring Spain. Higher seroprevalence values in the NUTS2 Centro region were consistent with incidence data from humans and seroprevalence studies in dogs. On the other hand, the low values in the Alentejo and the high values in the northern subregions may be the result of geographical shifts in parasite circulation due to climate change and should prompt localized and integrated, vector, canine, and human research, following a One Health approach.

Pregnant women with impaired tolerance to an oral glucose load in the afternoon: evidence suggesting that they behave metabolically as patients with gestational diabetes

OBJECTIVE

In previous studies we observed the existence of a circadian variation of the blood glucose response to oral glucose in pregnant women with higher values at 4 PM. Some women with increased risk of diabetes with normal oral glucose tolerance tests at 8 AM also had values above maximum normal levels at 4 PM. The aim of this trial was to determine the clinical significance of this impaired tolerance in the afternoon.

STUDY DESIGN

Seventy-seven pregnant women with normal risk of diabetes (65 of normal weight and 12 overweight), 75 with increased risk of diabetes (26 overweight), and 12 patients with gestational diabetes were incorporated in the study. All women underwent two oral glucose tolerance tests (1.5 gm/kg) at 31 to 32 weeks' gestation at 8 AM and 4 PM with a 1-week interval. At 33 weeks' gestation a whole-day blood glucose profile was performed with usual food intake; samples were withdrawn before each meal and at 30, 60, and 120 minutes after each meal. The weight of the newborns was recorded.

RESULTS

(1) Results of oral glucose tolerance tests confirmed a circadian variation of the response in all groups; (2) 37 women with increased risk of diabetes had higher values after oral glucose tolerance testing than the normal threshold at 4 PM but not at 8 AM; (3) among women with normal risk of diabetes all values were within the normal range despite the circadian variation; (4) blood glucose levels during whole-day profiles were normal in women with normal risk of diabetes and with increased risk of diabetes with normal oral glucose tolerance testing at 4 PM, whereas all women with increased risk of diabetes and impaired tolerance in the afternoon showed hyperglycemic episodes; (5) the percentage of newborns with high weight (>90th percentile) among women with increased risk of diabetes and abnormal oral glucose tolerance tests at 4 PM was similar to the percentage found in women with gestational diabetes and much higher than the one observed in women with normal oral glucose tolerance tests in the afternoon.

CONCLUSIONS

The impairment of the response to oral glucose tolerance testing seen in some patients with increased risk of diabetes at 4 PM but not at 8 AM seems of clinical significance in view of the abnormal whole-day blood glucose profile these women had and the weights of the newborns.