The Parasitemia has Contributed to the Severity of Cases of Visceral Leishmaniasis

Abstract

Visceral leishmaniasis (VL) occurs due to the evolution, virulence, and adaptation of Leishmania, vector biology, host immune system evasion, and reservoir hosts. Parasitemia can be involved as a warning regarding the clinical severity of VL The present study aims to evaluate the relationship between parasitemia and the prognosis of individuals with VL. Blood and bone marrow samples from individuals with VL were analyzed to identify parasite and quantify or measure parasite burden. Individuals were classified in the clinical score model of risk of death by disease proposed by Coura-Vital et al. (PLoS Negl Trop Dis 8(12): e33742014, 2014). 39/74 individuals presented a better prognosis, and 35/74 individuals presented a worse prognosis. HIV + VL co-infection was present in 32 individuals, of which 12 were considered severe. The group aged 51 to 64 was classified as severe, with a decrease in leukocytes (p-value 0.0295) and neutrophils (p-value 0.0476). L. infantum DNA was identified in blood and bone marrow, in 69 individuals, and not detected in 5 individuals. The quantification of the parasite showed greater parasitemia in bone marrow (P = 0.0003) with an average of 4.70 × 10⁴ Leishmanias/mL about blood, with 0.29 × 10⁴ Leishmanias/mL. Individuals in the age group aged 51 to 64 co-infected with HIV + VL had higher parasitemia (p-value 0.0150) with 2.44 × 10⁴ Leishmanias/mL in blood and bone marrow than in the group aged 20 to 50. Parasitemia, measured by molecular biology in blood and bone marrow, was related to the worst clinical prognosis of VL in the age group aged 51 to 64.

Keywords: Clinical prognosis; Parasitemia; Severity of illness; Visceral leishmaniasis.

Fig. 1

Hematological data according to age group. (Total leukocytes Mann–Whitney tests *p-value 0.0295. Neutrophils, Mann–Whitney test *p-value 0.0476.)

Fig. 2

Distribution of parasitemia by age groups. (Mann Whitey test p-value < 0.05. The qPCR was sensitive to identify the same behavior of the distribution of parasitemia in the marrow and blood in the age groups, demonstrating that the technique can be used in the routine diagnosis of VL with blood samples, less invasive and of lower risk to the individual. A Blood parasitemia. Age groups: General Group (n = 69) *p-value 0.0300. HIV + LV Group (n = 27) *p-value 0.0150. LV Group (n = 42) p-value 0.2420. B Bone marrow parasitemia. Age groups: general group (n = 69) *p-value 0.0227. HIV + LV (n = 27) *p-value 0.0495. LV Group (n = 42) p-value 9573.)

Fig. 3

Worldwide distribution of visceral leishmaniasis (VL) and L. infantum. A Distribution of visceral leishmaniasis cases on the world. Adapted of Burza et al. 2018 (33). The intense purple color represents the countries with the greatest number of cases reported on the world. The green color represents the countries not reported cases of VL. B Distribution of Leishmania infantum on the world. Adapted of WHO, 2010 (34). The orange color represents the spread L. infantum in many countries. The green color represents the countries without occurrence of L. infantum. C Overview of visceral leishmaniasis in Brazil caused for L. infantum, and the spread of the disease between states. The intense red color represents the states with the highest number of reported cases and with an intense spread of the disease in 2022. The gray area represents the state without the presence of L. infantum. The state of Ceará is where the present study was realized, demonstrates higher endemicity of VL