Sociodemographic characteristics and comorbidities

Data from 42 of the 45 hospitals or hospital centers in Mainland Portugal was available for analysis.

Sociodemographic characteristics of VL cases are represented in Table 1. A total of 221 cases of VL were diagnosed between 2010 and 2020 in the hospitals included: 201 as primary (or incident) cases and 20 as relapsing cases (first episode diagnosed before 2010). Of the 114 cases provided by the DGS, notified during this period, all but 13 were also identified through the hospital searches.

Table 1 Sociodemographic characteristics of visceral leishmaniasis cases diagnosed in public hospitals in Mainland Portugal in 2010–2020

Median age was 41 years old (IQI: 28–50) and male sex was predominant. Age distribution of cases of VL is represented in Fig. 1. Approximately half of the cases were diagnosed in hospitals in the Lisbon Metropolitan Area (Área Metropolitana de Lisboa - AML) region. Only three cases (1.4%) were imported (from Brazil n = 2 and East Africa n = 1). Migrants represented approximately 20% of patients diagnosed, most of them born in sub-Saharan Africa (27/33) or Brazil (4/33). The two most common occupation status reported, accounting for around half of all patients, were unemployment (24.2%) or working in commerce/industry (29.5%). Patients reported living in a detached house (58.3%), apartment (18.3%) or other (23.3%, including shelter, nursing home, prison or homeless). Contact with domestic animals was common (73.4%), especially dogs. Moreover, close contact with animals with leishmaniasis was described for 9/57 of patients. No clear seasonality was seen in respect to month of presentation of autochthonous primary episodes to healthcare, although March and June accounted for the most admissions or first consultations (12.0% and 11.5% of total, respectively).

Fig. 1

Age distribution (in years) of cases of visceral leishmaniasis diagnosed in 2010–2020 (n = 221)

Immunosuppressing conditions were present in 60.6% of patients. HIV infection/AIDS was reported in 53.5% of patients. Median CD4 cell count at time of diagnosis was 59.0/µlL (85.1% of patients had counts < 200/µl). Chronic pharmacologic immunosuppression for inflammatory diseases was reported in 10.8% of patients and other causes of immunosuppression included: solid organ transplant (n = 4), hematopoietic stem cell transplant (n = 1), solid organ malignancy (n = 4) and hematologic malignancy (n = 2). Immunosuppressing conditions and comorbidities of leishmaniasis patients are represented in Table 2.

Table 2 Immunosuppressing conditions and comorbidities of visceral leishmaniasis patients diagnosed in public hospitals in Mainland Portugal in 2010–2020

The estimated incidence of VL by year and by NUTS2 region is represented in Fig. 2. Globally, there was a significant decrease in incidence from 2010 to 2015–2016 (P = 0.001, CST); however, incidence subsequently increased and, in 2019–2020, it was significantly higher than in 2015–2016 (P = 0.030, CST). The Alentejo, Algarve and Centro regions presented increasing incidence in the 2017–2020 period. Figure 3 shows the incidence of VL by NUTS3 and municipality. The number of cases of VL diagnosed between 2010 and 2020, inclusively, and the incidence in this period by NUTS2 and NUTS3 region are also provided in Table 3. In the study period, the estimated incidence was highest in the Algarve (0.495 cases /100,000 population /year) and lowest in the Norte NUTS2 region (0.095 cases /100,000 population /year).

Fig. 2

Yearly incidence of visceral leishmaniasis between 2010 and 2020 per 100,000 population, in Mainland Portugal and in each NUTS (Nomenclature of Territorial Units for Statistics) 2 region

Fig. 3

Mean annual incidence between 2010 and 2020, per 100,000 population, of visceral leishmaniasis by: a NUTS (Nomenclature of Territorial Units for Statistics) 3 region; b municipality

Table 3 Number of cases of visceral leishmaniasis diagnosed in public hospitals in Mainland Portugal between 2010 and 2020, inclusively, and estimated mean annual incidence in this period, per 100,000 population, by NUTS (Nomenclature of Territorial Units for Statistics) 2 and NUTS3 regionClinical aspectsClinical manifestations and laboratory alterations

Clinical presentation aspects of incident VL primary episodes are summarized in Table 4 globally and by group: children 5 years of age or younger (CU5), non-immunosuppressed adults and children over 5 years old (NISA), people living with HIV (PLWH) and non-HIV infected immunosuppressed adults (ISA).

Table 4 Clinical presentation characteristics of visceral leishmaniasis primary episodes, diagnosed in public hospitals in Mainland Portugal, and incident between 2010 and 2020, globally and by group

Median time from onset of signs/symptoms to first presentation to healthcare was 4 weeks globally (IQI: 2–11) and was significantly different between groups (shorter in children under 5 years old, P = 0.010, H = 11.326, df = 3). In ISA, median time from start of immunosuppressive therapy to onset of signs/symptoms was 16 weeks (IQI: 12–66). Over 90% of patients in all groups were admitted as inpatients. Median duration of hospitalization was 20 days (IQI: 12–36) and was significantly different between groups: shortest in children [14] and longest in ISA [27] (P ≡ 0.040, KWT, H = 13.247, df = 3). Admission to critical care was only observed in ISA (16.7%) or in PLWH (13.0%). Fever was the most common presenting symptom (71.9%), followed by fatigue (69.8%), anorexia (52.5%) and weight loss (49.7%). Compared to NISA, fever was significantly less common in PLWH and more common in CU5, and the highest temperature was lower in PLWH and higher in CU5. Splenomegaly was detected in 90.0%, hepatomegaly in 71.8% and lymphadenopathy in 23.0%. Frequent laboratory abnormalities included: anemia (98.9%), thrombocytopenia (90.2%), leukopenia (88.3%), C-reactive protein (CRP) elevation (93.1%) and hepatic cytolysis or cholestasis (55.7%). Acute kidney failure was detected on admission in 14.6% of patients and was more common in ISA (P ≡ 0.004, FET). Criteria for HLH were met in 14 patients: 10 CU5 (40.0% of cases) and 4 in ISA (16.7%). Considering primary episodes and relapses, atypical presentations were diagnosed in 14 patients (8.5%), representing 12.8% of PLWH and 16.7% of ISA. Involvement was: colorectal (n = 6), duodenal/ileal (n = 7), gastric (n = 4), peritoneal (n = 1), pleural (n = 1), and bronchial (n = 1). Simultaneous involvement of the skin (with CL) was confirmed in 5.9% of patients. Coinfection/superinfection was detected in 42.4% of patients, without significant differences between groups, and was caused by the microbiological agents described in Supplementary Fig. 2. Respiratory and oropharyngeal/esophageal infections were the most common and Candida sp. and Escherichia coli were the most implicated microorganisms.

Diagnosis

Diagnosis, treatment, and outcome aspects of incident VL primary episodes are summarized in Table 5, globally and by group. Median time from presentation to diagnosis was 10 days (4.5–19.5) and was significantly different between groups: shortest in CU5 (5.5 days) and longest in ISA (17.5 days) (P ≡ 0.011, KWT, H = 11.192, df = 3). Samples most frequently used for direct diagnosis were: bone marrow (94.1%) and blood (25.0%). Techniques most often used in bone marrow samples were: microscopy (95.6%), PCR (41.6%), and culture (22.7%). Positivity rate was similar for PCR, microscopy, and culture (81.7%, 80.9% and 75.0%, respectively) and was not significantly different between groups. In blood samples, PCR was the technique most used for direct diagnosis (70.3%) and was positive in 73.1% of cases. In all cases in which Leishmania species identification was attempted and successful (n = 59), L. donovani complex was identified (by molecular biology techniques). Serologic techniques were used in 52.5% of patients, most commonly immunofluorescent antibody test (73.3%) and enzyme-linked immunosorbent assay (17.8%). Serology was positive in 82.9% of patients, ranging from 72.4% in PLWH to 92.3% in CU5, although this difference was not statistically significant (P ≡ 0.482, FET).

Table 5 Diagnosis, treatment, and outcome aspects of visceral leishmaniasis primary episodes, diagnosed in public hospitals in Mainland Portugal, and incident in the period between 2010 and 2020, globally and by groupTreatment and outcome

In most cases, treatment was initiated on the same day of diagnosis (median time 0 days, IQI: 0–1). Liposomal amphotericin B (LAmB) was used for primary treatment in 98.8% of cases and meglumine antimoniate for the rest (n = 2, both CU5). Side effects were reported globally in 30.5% of patients (n = 40) and were significantly less common in CU5 (P ≡ 0.025, CST, χ 2 = 9.365, df = 3). The reported side effects included: acute kidney injury and/or hypokalemia (19.8%, n = 26), hepatotoxicity (n = 4), vomiting and/or diarrhea (n = 4), fever/shivering (n = 3), myalgia (n = 2), anaphylaxis (n = 1). In PLWH, antiretroviral therapy was initiated or reinitiated in 48.6% of patients; one case of paradoxical immune reconstitution inflammatory syndrome was documented. In ISA, withdrawal of immunosuppressive drugs or reduction of dose was done in 66.7% of cases. Median time to defervescence after initiation of anti-Leishmania therapy was 3.0 days (IQI: 1.75–5) and was significantly shorter for CU5 and longer for ISA (P ≡ 0.008, KWT, H = 11.823, df = 3). Improvement by day 7 after initiation of anti-Leishmania therapy was documented in 88.6% of cases, ranging from 69.6% in ISA to 87.1% in PLWH and 100% in CU5 (P ≡ 0.003, FET). Improvement by day 30 after initiation of therapy was documented in 96.4% of patients and was over 95% in all groups except ISA (82.6%, P ≡ 0.008, FET). Death occurred in seven cases (4.3%): four PLWH (5.2%) and three ISA (13.0%). Secondary prophylaxis was implemented in 54.9% of PLWH, but in only 16.7% of ISA (P = 0.001, χ 2 = 10.599, df = 1); drugs used for prophylaxis were LAmB (97.7%) and miltefosine (2.3%). Cure tests were performed for 16.9% of patients, especially PLWH, and median time to cure test was 6.1 weeks after completing primary treatment (IQI: 3.25–23.5).

Relapses

In total, there were 151 episodes of relapse in the study period, affecting 61 patients. The number of relapses per patient ranged from 1 to 9. Relapses were documented only in PLWH and in ISA, at a similar rate: 0.175 and 0.147 episodes per patient-year, respectively (P ≡ 0.578, CST). Relapse-free survival was significantly higher for PLWH than for ISA at nine months follow-up (P ≡ 0.023, χ 2 = 5.203, df = 1) but not at 48 months (P ≡ 0.453, χ 2 = 0.562, df = 1) (Fig. 4a). Relapse-free survival was slightly higher for patients on any prophylaxis in the first 10 months after a primary VL episode or a relapse (Fig. 4b), but this difference did not reach statistical significance (P ≡ 0.396, χ 2 = 0.720, df = 1 for primary episodes; P ≡ 0.674, χ 2 = 0.177, df = 1, for relapses). Rate of relapse was significantly higher in the 12 months after a relapse than after a primary episode, either with or without prophylaxis (P ≡ 0.023, χ 2 = 5.195, df = 1; P ≡ 0.012, χ 2 = 6.364, df = 1, respectively). Use of LAmB for prophylaxis at doses of 4–5 mg/kg every 2–3 weeks was associated with significantly higher relapse-free survival at 12 months than doses of 3–4 mg/kg every 4 weeks, for primary episodes (P ≡ 0.048, χ 2 = 3.893, df = 1), but not for relapses (P ≡ 0.862, χ 2 = 0.030, df = 1) (Fig. 4c).

Fig. 4

Relapse-free survival of visceral leishmaniasis patients: a according to group; b according to use of prophylaxis and primary/subsequent episode; c according to dose of liposomal amphotericin B used and primary/subsequent episode

In relapse cases, compared to primary episodes (in PLWH or ISA), time from onset to presentation was significantly shorter (median 3.0 vs. 4.0 weeks, P ≡ 0.030, U = 3377.0). Drugs used for secondary prophylaxis after a relapse included LAmB (80.5%), miltefosine (6.5%), and LAmB + miltefosine (6.5%). Outcome of treatment of VL relapses according to drug used is represented in Table 6. The percentage of episodes with improvement was higher for combination therapy at 7 (90.0 vs. 80.8%) and 30 days (93.3 vs. 83.5%) after initiation of therapy, but this difference was not statistically significant (P ≡ 0.238, χ 2 = 1.395, df = 1; P ≡ 0.235, FET, respectively). Subsequent relapse-free survival after a relapse was not significantly different for patients treated with monotherapy or combination therapy (P ≡ 0.816, χ 2 = 0.054, df = 1). Side effects were less commonly reported for LAmB (39.4%), compared to miltefosine (55.6%) or meglumine antimoniate (71.4%).

Table 6 Outcome of treatment of episodes of relapse of visceral leishmaniasis, diagnosed in public hospitals in Mainland Portugal in 2010–2020, according to drug or combination of drugs usedNotification of cases and regional differences

Only 49.7% of incident VL cases in 2010–2020 were notified to the National Epidemiologic Surveillance System; cases in CU5 were significantly more notified (75.8%, P ≡ 0.006, χ 2 = 12.353, df = 3). The percentage of cases notified was significantly different according to the region of the hospital: Norte 45.7%, Centro 69.7%, AML 44.0%, Alentejo 81.8%, and Algarve 70.8% (P = 0.007, χ 2 = 14.106, df = 4); notification was not significantly different for patients admitted to Internal Medicine (45.6%) or Infectious Diseases departments (46.3%, P = 0.942, χ 2 = 0.005, df = 1).

The main regional differences in presentation and management of VL are summarized in Table 7. The Alentejo was the region with a lower percentage of cases in PLWH/ISA and a higher percentage in CU5. In the Algarve and the Alentejo regions more patients were admitted to Internal Medicine vs. Infectious Diseases departments and time from presentation to diagnosis was longer in these regions. Use of serology for diagnosis was more common in the Alentejo, and less common in the Algarve.

Table 7 Presentation and management of incident visceral leishmaniasis cases diagnosed in public hospitals in Mainland Portugal in 2010–2020, by NUTS2 region of residence: Norte, Centro, Área Metropolitana de Lisboa, Alentejo and AlgarveAssociations in VL

In univariate analysis, non-improvement at day 7 after initiation of anti-Leishmania therapy for primary treatment of VL was associated with male sex, immunosuppression, chronic organ dysfunction, renal failure at admission, severe leukopenia (< 1500/µl), coinfection/superinfection and CRP level over 100 (Table 8a). However, in multivariate analysis, CRP level over 100 was the only statistically significant factor.

Table 8 Potential factors for non-improvement at 7 days after starting treatment and for non-reporting of primary cases newly diagnosed between 2010 and 2020 in public hospitals in Mainland Portugal, according to logistic regression models to estimate crude and adjusted odds ratio values

Non-reporting of a VL case was associated in univariate analysis with age over 5 years old, immunosuppressed status, admission to a hospital located in the Norte or AML region and admission to a secondary center. In multivariate analysis, age over 5 years old, admission to a hospital located in the Norte or AML region and admission to a secondary center remained significant (Table 8b).