Recurrent Visceral Leishmaniasis in a Case With Interleukin-12 Receptor Beta-1 Deficiency.

PURPOSE: In this study, we present the case of a children who was followed up for recurrent visceral leishmaniasis and diagnosed with IL-12Rß1 deficiency. METHODS: A female patient who received Bacille Calmette-Guérin (BCG) vaccine 2 months after birth and developed visceral leishmaniasis at the age of 91 months was subsequently diagnosed with IL-12Rß1 deficiency. The patient's diagnosis and treatment process were examined retrospectively. RESULTS: IL-12Rß1 deficiency is an autosomal recessive disease characterized by susceptibility to recurrent and/or severe infections caused by weakly pathogenic mycobacteria and salmonella. Infections with other intramacrophagic organisms may also occur, although rarely. Based on this information, it is believed that the mutation in the IFN-γ/IL-12 axis in our patient predisposed her to recurrent Leishmania infections. CONCLUSION: This study adds to the limited literature on IL12RB1 deficiency as a cause of VL. Patients diagnosed with VL should be evaluated immunologically, as recurrent Leishmania infections may occur in those with IL-12Rß1 defects.

Navigating Diagnosis and Treatment Dilemmas in Visceral Leishmaniasis Reactivation in a HIV-Positive Patient.

Reactivation of visceral leishmaniasis (VL) in human immunodeficiency virus (HIV)-positive patients poses complex management challenges, requiring tailored treatment approaches and robust follow-up strategies. There are very few case reports of visceral leishmaniasis (VL) published in Sri Lanka as of today. Here, we present a case of a 38-year-old, HIV-positive male who was treated for a reactivation of VL. He presented with a prolonged febrile illness without an identifiable infection focus. The evaluation confirmed VL reactivation. Using current evidence-based guidelines, our patient was treated with intravenous liposomal amphotericin B and achieved a parasitological cure.  By exploring the challenges associated with managing VL among HIV-positive individuals, we emphasize the importance of reliable follow-up protocols and investigations to assess treatment success, ensuring optimal patient outcomes.

Rapid antigen detection test for diagnosis of post kala-azar dermal leishmaniasis: application of CL Detect™ rapid test for active case detection in the endemic area.

Post-kala-azar dermal leishmaniasis (PKDL) is a skin condition that occurs in a small percentage of people who have been cured of visceral leishmaniasis (VL), and contributes to transmission of VL. The rK39 rapid test cannot decisively diagnose PKDL due to presence of antileishmanial antibodies from past VL episodes. CL Detect™ Rapid Test, an in-vitro diagnostic test that detects Leishmania antigen peroxidoxin, was assessed for diagnosing PKDL. The CL Detect RDT had 73.3% sensitivity and 100% specificity in the study. The test can be used as a primary screening tool to monitor PKDL in endemic regions and identify active Leishmania infection.

Can letrozole be repurposed for the treatment of visceral leishmaniasis?

Visceral leishmaniasis, caused by Leishmania infantum in New World countries, is the most serious and potentially fatal form of leishmaniasis, if left untreated. There are currently no effective prophylactic measures, and therapeutic options are limited. Therefore, we investigated whether the aromatase inhibitor letrozole (LET), which is already used to treat breast cancer, has an antileishmanial activity and/or immunomodulatory potential and therefore may be used to treat L. infantum infection. LET was active against L. infantum promastigote and amastigote life cycle stages in an in vitro infection model using human THP-1 cell-derived macrophages. In human peripheral blood leukocytes ex vivo, LET reduced the internalized forms of L. infantum by classical monocytes and activated neutrophils. Concomitantly, LET stimulated the production of IL-12/TNF-α and decreased the production of IL-10/TGF-ß by peripheral blood phagocytes, while in T and B cells, it promoted the production of TNF-α/IFN-γ and decreased that of IL-10. In a murine infection model, LET significantly reduced the parasite load in the liver after just 5 days and in the spleen after 15 days. During in vivo treatment with LET, the production of TNF-α/IFN-γ also increased. In addition, the proportion of developing granulomas decreased and that of mature granulomas increased in the liver, while there was no significant change in organ architecture in the spleen. Based on these data, repositioning of LET may be promising for the treatment of visceral leishmaniasis in humans.

Interleukin-27 Regulates Adaptative Immune Responses Associated With Control of Parasite Replication in Canine Leishmaniasis.

Interleukin 27 (IL-27) is a cytokine that regulates susceptibility to Leishmania infantum infection in humans and experimental models. This cytokine has not yet been described in canine leishmaniasis (CanL). Therefore, we investigated whether IL-27 has a regulatory role in CanL. The EBI3 and p28 subunits of IL-27 were measured in splenic leukocytes culture supernatant from dogs with CanL and compared to control dogs. We also correlated EBI3 and p28 levels with IL-21, anti-L. infantum antibodies and parasite loads. We performed functional assays followed by IL-27 blockade and measured parasite loads, production of cytokines in splenic leukocytes culture supernatant, and the expression of PD-1, CTLA-4, phospho-Stat-1/3, T-bet, GATA3 and nitric oxide production (NO). Both IL-27 subunits increased in the supernatant of dogs with CanL compared to control dogs. EBI3 and p28 levels showed a moderate positive correlation with IL-21 (r = 0.67, p < 0.0001 and r = 0.45, p < 0.012, respectively), and the EBI3 subunit was positively associated with anti-L. infantum IgG antibodies (r = 0.38, p < 0.040) and parasite load (r = 0.47, p < 0.009). IL-27 and IL-21 participate of immune responses in CanL. IL-27 may be associated with the failure of immunity to control parasite replication via upregulation of the expression of PD-1, CTLA-4, T-bet and NO in splenic leukocytes from dogs with CanL. These findings suggest that the pathways regulated by IL-27 are involved in CanL pathogenesis in the host, and may be targets for new therapies.

Kupffer cell and recruited macrophage heterogeneity orchestrate granuloma maturation and hepatic immunity in visceral leishmaniasis.

In murine models of visceral leishmaniasis (VL), parasitization of resident Kupffer cells (resKCs) is responsible for early growth of Leishmania infantum in the liver, which leads to granuloma formation and eventual parasite control. We employed the chronic VL model, and revealed an open niche established by KCs death and their migration outside of the sinusoids, resulting in their gradual replacement by monocyte-derived KCs (moKCs). While early granulomas were composed of resKCs, late granulomas were found outside of the sinusoids and contained resKC-derived macrophages, and monocyte-derived macrophages (momacs). ResKCs and moKCs within the sinusoids were identified as homeostatic/regulatory cells, while resKC-derived macrophages and momacs within late granulomas were pro-inflammatory. Despite the infection being largely confined to the resKC-derived macrophages, in the absence of monocyte recruitment, parasite control was strongly compromised. Macrophage heterogeneity, involving migration and reprogramming of resKCs, along with recruitment of monocyte-derived cells, is a hallmark of granuloma maturation and hepatic immunity in VL.

Dog complement system is less effective against Leishmania infantum than human complement.

Dogs are important reservoir hosts for Leishmania infantum, the causative agent of visceral leishmaniasis. The complement system, as part of the innate immune defense, is responsible for initiating the fight against pathogens that may invade an organism. A failure of the complement to combat L. infantum may explain, at least in part, why a mammal species is more or less susceptible to visceral leishmaniasis. The objective of this study was to compare the effectiveness of human and dog complement systems against L. infantum parasites. The results showed that dog serum was less effective than human serum at killing promastigote and amastigote-like forms. We also compared the efficiency of human and canine sera in classic and alternative hemolytic assays, as well as the serum efficiency of non-infected and Leishmania-infected dogs. Serum from dogs was less hemolytic than human serum in both pathways tested, but the efficiency of serum from infected dogs was higher than that of non-infected dogs. When testing C3b deposition assays on parasite surfaces, serum from infected dogs was more effective against amastigote-like forms than serum from non-infected dogs. However, both types of serum proved equally effective on promastigotes, while serum from infected dogs was more effective on amastigote-like forms. Considering the efficiency of the complement system, our results indicate that dogs are more susceptible to visceral leishmaniasis than humans are.

Visceral leishmaniasis complicated with hemophagocytic lymphohistiocytosis and resistant to amphotericin B: a case report.

INTRODUCTION: Hemophagocytic lymphohistiocytosis characterized by hemophagocytosis leading to uncontrolled inflammation; the most common etiology in secondary cases of hemophagocytic lymphohistiocytosis is viral infections, especially Epstein-Barr virus. Visceral leishmaniasis is a vectorborne protozoal disease caused by Leishmania donovani complex. It is common in tropical and subtropical regions, with 50,000-90,000 new cases annually. CASE PRESENTATION: A 15-month-old Arab female was admitted to our hospital with 15 days of fever and decreased weight. On clinical examination, she had a markedly enlarged liver and spleen that were palpable 4 cm and 6 cm below the costal margin, respectively. The peripheral blood smear showed hypochromic microcytic anemia, poikilocytosis, reactive lymphocytosis, and mild thrombocytopenia. Bone marrow aspiration did not show malignancy or any other pathological findings. The patient was put on antibiotic therapy without improvement. Repeated bone marrow aspiration showed erythrophagocytosis; intracellular small round organisms looked like the amastigote form of Leishmania (Donovan bodies) with no evidence of malignancies. Her lab values showed ferritin greater than 500 ug/L, pancytopenia, and hypertriglyceridemia. The patient was diagnosed with hemophagocytic lymphohistiocytosis secondary to visceral leishmaniasis. CONCLUSION: Hemophagocytic lymphohistiocytosis secondary to visceral leishmaniasis is an extensively rare phenomenon in the medical literature that causes challenges in diagnosis and management. Steroids should be used wisely to not cover the symptoms of infections or malignancy, and amphotericin B resistance should be kept in mind in unresponsive Leishmania cases.

Bronchoalveolar Lavage Fluid Metagenomic Second-Generation Sequencing Assists in Guiding the Treatment of Visceral Leishmaniasis: A Case Report.

Purpose: The incidence of visceral leishmaniasis (VL), a global infectious disease, has been on the rise in China's Hebei province. When patients achieve clinical cure, they often do not reach an etiological cure, which may lead to recurrence of the disease. Here, we report a case of visceral leishmaniasis with a negative blood smear and bone marrow cytology. Patients and Methods: A 65-year-old man and bronchoalveolar lavage fluid mNGS. Results: A 65-year-old man developed a chronic fever, anorexia, splenomegaly, and pancytopenia. The blood metagenomic second-generation sequencing (mNGS) revealed Leishmania sequence readings, which led to the diagnosis of VL. After sodium antimony gluconate treatment, the blood smear and bone marrow cytology revealed no Leishmania bodies. However, pancytopenia and respiratory failure did not fully subside, and cardiotoxic damage emerged. The bronchoalveolar lavage fluid (BALF) mNGS was performed to detect the pathogen. Through BALF mNGS, Leishmania sequence was still detectable. Therefore, after the ECG returned to normal, antimony sodium gluconate was administered as a next course of treatment. Conclusion: BALF mNGS may assist in evaluating the therapeutic efficacy of VL with respiratory failure, especially in patients with negative blood and bone marrow cytology.

Accurate detection of visceral leishmaniasis is essential for clinical diagnosis.It is uncommon to use alveolar lavage fluid mNGS in etiological diagnosis.Patient with negative bone marrow cytology may refer to alveolar lavage fluid mNGS.

Barriers and facilitators of visceral leishmaniasis case management in the Amhara Region, Northwest Ethiopia: an exploratory qualitative study.

BACKGROUND: Visceral leishmaniasis (VL) is among the world's most serious public health threats, causing immense human suffering and death. In Ethiopia, little is known about the barriers and facilitators of visceral leishmaniasis case management. This study aimed to explore such barriers and facilitators in the Amhara Regional State, Northwest Ethiopia. METHODS: An exploratory qualitative study was conducted on 16 purposively selected patients and key informants from May 8 to June 2, 2023. The study participants were recruited using the maximum variation technique. The interviews were audio recorded, transcribed verbatim, and translated into English. Thematic analysis was employed using Atlas.ti 9 software with a blended approach of both deductive and inductive coding. RESULTS: The study identified a variety of issues that hinder the success of visceral leishmaniasis case management. Treatment centers face frequent interruptions of medicinal supplies, a lack of funding, and a lack of trained healthcare providers. A lack of support from health authorities, including weak supervision and feedback systems, is also a source of concern. Most patients receive treatments after significant delays, which is primarily due to low awareness, poor surveillance, and misdiagnosis by healthcare workers. The case management is further constrained by malnutrition, VL-HIV co-infection, and other comorbidities. Despite these issues, we found that effective collaboration between hospital units and VL treatment centers, acceptance by hospitals, and the caring attitude of healthcare workers play a positive role in facilitating the program's effectiveness. CONCLUSIONS: Despite the existence of certain efforts that facilitate the program's effectiveness, VL remains largely neglected, with little government attention or intervention. Such inattention is the root cause of most of the issues. Despite limited resources, most issues could be resolved with cost-effective strategies if health authorities at all levels have the will and commitment to do so.

In silico and in vitro evaluation of the immunogenic potential of Leishmania donovani ascorbate peroxidase and its derived peptides.

The control and eradication of any infectious disease is only possible with a potential vaccine, which has not been accomplished for human visceral leishmaniasis (VL). The lack of vaccines may increase the risk of VL outbreaks periodically in endemic zones. Identifying a reliable vaccine candidate for Leishmania is a major challenge. Here, we considered Leishmania donovani ascorbate peroxidase (LdAPx) for its in vitro evaluation with the hope of future vaccine candidates for VL. LdAPx was selected based on its unique presence in Leishmania and virulence in VL pathogenesis. Initially, we found antibodies against recombinant LdAPx (rLdAPx) in the serum of VL patients. Therefore, using bioinformatics, we predicted and selected ten (MHC class I and II) peptides. These peptides, evaluated in vitro with PBMCs from healthy, active VL, and treated VL individuals induced PBMC proliferation, IFN-γ secretion, and Nitric Oxide (NO) production, indicating host-protective immune responses. Among them, three peptides (PEP6, PEP8, and PEP9) consistently elicited a Th1-type immune response in PBMCs. Treated VL individuals showed a stronger Th1 response compared to active VL patients and healthy subjects, highlighting these peptides' potential as vaccine candidates. Further studies are on the way toward evaluating the LdAPx-derived peptides or sub-unit vaccine in animal models against the L. donovani challenge.

Hemophagocytic lymphohistiocytosis secondary to visceral leishmaniasis: A case report of a rare complication of visceral leishmaniasis.

Hemophagocytic lymphohistiocytosis (HLH) is a rare, potentially life-threatening clinical syndrome characterized by hyperactivation of inflammatory mediators and harmful end-organ damage. Visceral leishmaniasis (VL)-induced HLH is a rare disease with significant diagnostic and management implications. Herein, we present a case of secondary HLH as a complication of visceral leishmaniasis in a two-year-old toddler. A 2-year-old male toddler was admitted for evaluation of a prolonged 4-week fever. Accompanying the fever, he developed progressive abdominal swelling, intermittent bilateral nasal bleeding, and repeated chest-focus infections of similar duration. The patient was acutely sick, with chronic signs of malnutrition (mid-upper arm circumference of 10.5 cm), fever (39 °C), tachypnea (70 breaths/min), tachycardia (132 beats/min), pallor, and hepatosplenomegaly. Initial investigation revealed leukopenia (2240/µl), anemia (7.3 g/dl), and severe thrombocytopenia (26,000/µl). With consideration of febrile neutropenia, the patient was started on cefepime with further revision to vancomycin and meropenem based on the culture result. After 10 days of persistent fever and poor clinical condition, an immunochromatographic rapid test with the rK39 antigen was conducted, and the patient was found to be positive for Leishmania spp. Intravenous liposomal amphotericin B (AmBisome) was initiated. On the 6th day of treatment, the patient's clinical and laboratory profiles severely deteriorated, and further laboratory investigation showed elevated triglyceride (524 mg/dl) and ferritin levels (1500 ng/mL). VL-induced secondary HLH was confirmed, and intravenous dexamethasone was initiated. Subsequently, his clinical and laboratory findings significantly improved, and he was discharged with PO dexamethasone. Our case highlights the intricate nature of VL-induced HLH and the need for high index of suspicion and timely management.

[Optimization of the control strategy and research priorities to combat the resurgence of visceral leishmaniasis in China].

Leishmaniasis is a zoonotic parasitic disease caused by Leishmania infection and transmitted by sandflies. There are three main forms of leishmaniasis, including cutaneous leishmaniasis, visceral leishmaniasis and mucocutaneous leishmaniasis. China is mainly endemic for visceral leishmaniasis, which is a class C notifiable infectious disease in the country. Following concerted efforts, the transmission of visceral leishmaniasis had been controlled in most endemic foci of China by the end of 1958, with a few cases reported in western China. Due to global climate changes and population mobility, resurgence of visceral leishmaniasis has recently occurred in historical endemic areas of central and western China, which is characterized by gradual expansion of endemic areas and remarkable rebounding epidemics. Hereby, we summarize the national and global epidemiology and control strategy of visceral leishmaniasis, propose 8 key research areas and 12 key research topics for visceral leishmaniasis control, and recommend the establishment of the joint prevention and control mechanism of "human-animals-vectors" and the working mechanism of animal prevention for human diseases based on the One Health approach, so as to combat the resurgence of visceral leishmaniasis in China.

[Distribution and seasonal fluctuation of visceral leishmaniasis vectors sandflies in Henan Province in 2023].

OBJECTIVE: To investigate the geographical distribution and seasonal fluctuations of visceral leishmaniasis vectors sandflies in Henan Province in 2023, so as to provide insights into the prevention and control of visceral leishmaniasis vectors. METHODS: A total of 23 counties (districts) were sampled from 18 cities of Henan Province from May to September, 2023 as sandfly surveillance sites, and sandflies were captured using human capture and light trapping methods. Following morphological identification, the changes in the sandfly density were calculated at different months and in different breeding habitats. RESULTS: A total of 406 light traps were set at sandfly surveillance sites in Henan Province from May to September, 2023, and a total of 3 137 female sandlies were captured, with an average density of 7.73 sandlies/(light·night). A total of 1 494 Phlebotomus chinensis sandflies were captured, including 1 222 female sandflies, with an average density of 3.01 sandflies/(light·night), and the highest density of P. chinensis was found in Gongyi City [17.00 sandflies/(light·night)]. A total of 5 544 sandflies were captured using the human capture method, including 230 P. chinensis, and the density of P. chinensis appeared a unimodal distribution, with a peak in early July [5.81 sandflies/(light·night)]. Among different breeding habitats, the highest P. chinensis density was detected in pigpens [4.50 sandflies/(light·night)]. CONCLUSIONS: P. chinensis was predominantly distributed in hilly areas of northern and central-western Henan Province in 2023, and the sandfly density appeared a unimodal distribution. Intensified monitoring of visceral leishmaniasis vectors is recommended.

[Spatiotemporal clustering and hot spot analysis of visceral leishmaniasis in Gansu Province from 1993 to 2023].

OBJECTIVE: To investigate the spatiotemporal clustering characteristics of the reported incidence of visceral leishmaniasis (VL) in Gansu Province from 1993 to 2023, so as to provide insights into the containment of VL and prevention of VL recurrence. METHODS: County (district)-level epidemical data of VL in Gansu Province from 1993 to 2023 were collected, and the geographical information database of reported VL incidence in Gansu Province was created according to the county-level administrative code and electronic maps in Gansu Province. In addition, the spatial autocorrelation analysis and hot spot analysis of the reported VL incidence were performed in Gansu Province using the software ArcGIS 10.8. RESULTS: A total of 2 597 VL cases were reported in Gansu Province from 1993 to 2023, with an annual average incidence rate of 3.036/105. Spatial autocorrelation analysis showed spatial clustering of the reported VL incidence in Gansu Province (Moran's I = 0.605, Z = 5.240, P < 0.001), appearing high-high clustering features (Getis-Ord G = 0.080, Z = 4.137, P < 0.001), and high-high clustering of the reported incidence of VL was identified in Diebu County, Tanchang County, Zhouqu County and Wenxian County. Hot spot analysis showed hot-spot areas of the reported VL incidence in Tanchang County, Zhouqu County, Wudu District and Wenxian County along the Bailong River basins and cold-spot areas in Qin'an County and Gangu County. CONCLUSIONS: There was spatial clustering and hot spots of the reported VL incidence in Gansu Province from 1993 to 2023. Intensified surveillance and control is required to prevent the spread of VL.

[Distribution and seasonal fluctuation of visceral leishmaniasis vectors sandflie in Lüliang City of Shanxi Province in 2023].

OBJECTIVE: To investigate the distribution and seasonal fluctuations of visceral leishmaniasis vectors sandflies in Lüliang City, Shanxi Province, so as to provide insights into assessment of the visceral leishmaniasis transmission risk and formulation of visceral leishmaniasis control measures. METHODS: A total of 12 natural villages were sampled from Shilou County, Lishi District, Lanxian County, Linxian County and Wenshui County in Lüliang City, Shanxi Province from June to September, 2023, and sandflies were captured using light traps from 7 breeding habitats, including farmers' houses, sheep pens, cattle pens, chicken coops, pig pens, mule and horse pens, and loess-cave dwellings. Following morphological identification of the sandfly species, the distribution of sandflies and the seasonal fluctuations of the sandfly density were analyzed. In addition, the Leishmania was detected in sandflies using a real-time fluorescence quantitative PCR assay. RESULTS: A total of 2 831 sandflies were captured with 156 light traps in Lüliang City from June to September, 2023, including 2 638 female sandflies (93.18%) and 193 male sandflies (6.82%), and the average density was 16.91 sandflies/(light-night). The seasonal fluctuations of the sandfly density all appeared a unimodal distribution in all survey sites, and the sandfly density peaked in July and then declined rapidly. Among all types of breeding habitats, the greatest sandfly density was found in sheep pens [39.04 sandflies/(light-night)]. In addition, 4.08% (2/49) of the sandfly samples were tested positive for Leishmania nucleic acid as revealed by the real-time fluorescence quantitative PCR assay. CONCLUSIONS: Sandflies were widely distributed in Lüliang City, Shanxi Province in 2023, and the peak of the sandfly density was observed in July, which had a visceral leishmaniasis transmission risk. Intensified surveillance of visceral leishmaniasis and sandfly vectors is required and targeted vector control is recommended.

[Epidemiological features of visceral leishmaniasis cases in Henan Province from 2021 to 2023].

OBJECTIVE: To analyze the characteristics of visceral leishmaniasis cases in Henan Province, so as to provide insights into formulation of the visceral leishmaniasis control srtrategy. METHODS: All epidemiological data of reported visceral leishmaniasis cases in Henan Province from 2021 to 2023 were retrieved from the National Notifiable Disease Report Information Management System of Chinese Center for Disease Control and Prevention, and the epidemiological features and diagnosis of visceral leishmaniasis cases were descriptively analyzed. RESULTS: A total of 93 visceral leishmaniasis cases were reported in Henan Province from 2021 to 2023, with a male to female ratio of 2.58∶1, and including 2 imported cases from other provinces and 91 local cases. The number of visceral leishmaniasis cases peaked during the period between March and May, and between July and October. The reported visceral leishmaniasis cases had ages of 7 months to 74 years, with the largest number of cases found at ages of 0 to 9 years (26 cases, 27.96%), followed by at ages of 60 to 70 years (24 cases, 25.81%). Farmer (47 cases, 50.54%) and diaspora children (19 cases, 20.43%) were predominant occupations, and 91 local visceral leishmaniasis cases were found in 6 cities of Zhengzhou, Luoyang, Anyang, Hebi, Sanmenxia and Xuchang. The median duration from onset of visceral leishmaniasis to diagnosis was 20 days, and there were 25.81% (24/93) cases with 10 days and less duration from onset to diagnosis, 38.71% (36/93) cases receiving diagnosis at 11 to 30 days following onset, and 35.48% (33/93) cases receiving diagnosis for more than 30 days following onset. All cases were predominantly diagnosed in province- (60.00%) and city-level (28.89%) medical institutions. CONCLUSIONS: The number of visceral leishmaniasis is on the rise in Henan Province, with a gradually expanding coverage. Intensified monitoring of visceral leishmaniasis cases, dogs, and vectors, dog management, sandflies control and improved individual protection are recommended to prevent the spread of visceral leishmaniasis.

[Genetic polymorphisms of common sandflies in selected areas of Henan Province based on DNA barcoding].

OBJECTIVE: To characterize the species of common sandflies in Henan Province using DNA barcoding with cytochrome c oxidase subunit I (COI) gene as the molecular marker, and to analyze the genetic polymorphisms of sandflies, so as to provide insights into visceral leishmaniasis prevention and control in Henan Province. METHODS: Sandfly specimens were sampled from 13 sandflies surveillance sites from 2021 to 2023 in Anyang City, Zhengzhou, Luoyang and Xuchang cities (Zhengzhou-Luoyang-Xuchang areas) where visceral leishmaniasis cases were reported and in Jiaozuo and Xinxiang cities (Jiaozuo-Xinxiang areas) without visceral leishmaniasis cases reported. Genomic DNA was extracted from a single sandfly, and COI gene was amplified. The amplification product was subjected to bidirectional sequencing. Following sequence assembly, the species of sandflies was characterized through sequence alignment using the BLAST tool. The intra-specific and inter-specific genetic distances of sandflies were estimated among different areas using the software Mega 11, and phylogenetic trees were created. The polymorphisms of nucleotide sequences in the sandflies COI gene were estimated using the software DnaSP. The fixation index (FST) of different geographical isolates of sandflies was calculated using the Arlequin software, and the gene flow value (Nm) was used to measure the gene flow in the sandflies populations. In addition, the population genetic structure of different geographical populations of Phlebotomus chinensis was analyzed using the STRUCTURE software. RESULTS: A total of 978 sandflies were collected from 13 sandflies surveillance sites in Zhengzhou-Luoyang-Xuchang areas, Jiaozuo-Xinxiang areas and Anyang City of Henan Province from 2021 to 2023, and 475 sandflies were randomly sampled for subsequent detections. A total of 304 Ph. chinensis, 162 Se. squamirostris and 9 Se. bailyi were identified based on molecular biological detection of the COI gene, and Se. bailyi was reported for the first time in Henan Province. The intraspecific genetic distances of sandflies were 0.000 to 0.040, and the inter-specific genetic distances ranged from 0.133 to 0.161. Phylogenetic analysis revealed that each of the three sandfly species was clustered into a clade. The genetic polymorphisms of Ph. chinensis populations varied among different areas, with the highest haplotype diversity (0.966 ± 0.007) and the greatest nucleotide diversity (0.011) in Zhengzhou-Luoyang-Xuchang areas, and the lowest haplotype diversity (0.720 ± 0.091) and nucleotide diversity (0.004) in Anyang City. The dominant haplotype of Ph. chinensis populations was Pch_Hap_2 in Anyang City and Jiaozuo-Xinxiang areas, with moderate genetic differentiation (0.05 < FST < 0.15) and frequent gene exchange (Nm value > 1) between Ph. chinensis populations sampled from Anyang City, and Jiaozuo-Xinxiang areas. Population genetic structure analysis showed that the dominant component of Ph. chinensis populations was K5 in Anyang City and Jiaozuo-Xinxiang areas. No obvious dominant haplotype was observed in Ph. chinensis populations sampled from Zhengzhou-Luoyang-Xuchang areas, which had very high genetic differentiation (FST > 0.25) and little gene exchange (Nm value < 1) with Ph. chinensis populations from Anyang City, and Jiaozuo-Xinxiang areas, with K3 as the dominant component. In addition, there was no significant difference in the genetic polymorphism level among Se. squamirostris populations from the three areas. CONCLUSIONS: There are Ph. chinensis, Se. squamirostris and Se. bailyi in Henan Province, and S. bailyi is recorded for the first time in Henan Province by molecular biological assays. There are different levels of genetic differentiation and gene exchange among P. chinensis populations in different areas of Henan Province.

[Epidemiological characteristics of local visceral leishmaniasis in Beijing Municipality from 2021 to 2023].

OBJECTIVE: To investigate the epidemiological characteristics of local visceral leishmaniasis in Beijing Municipality from 2021 to 2023, so as to provide insights into formulation of the visceral leishmaniasis control strategy. METHODS: Epidemiological data of visceral leishmaniasis cases reported in Beijing Municipality from 2021 to 2023 were collected from the National Health Informatization Disease Prevention and Control Information System, and the epidemiological characteristics of local visceral leishmaniasis cases were analyzed using a descriptive epidemiological method. In November 2021 and 2023, 50 to 100 permanent residents were voluntarily selected within a 100 meter radius of sites where patients lived or acquired Leishmania infections, and venous blood was sampled for anti-Leishmania antibody testing. Venous blood was sampled from dogs for anti-Leishmania antibody testing in natural villages where patients lived or acquired Leishmania infections, or in districts where Leishmania infected dogs were reported. In addition, sandflies were captured with CO2 mosquito traps and fine mesh nets in natural villages where patients lived or acquired Leishmania infections from May to September, 2021 and 2023, for sandfly species identification. RESULTS: A total of 4 local visceral leishmaniasis cases were reported in Beijing Municipality from 2021 to 2023, with ages of 2 to 77 years, and acquiring Leishmania infections in Mentougou District (2 cases), Changping District (1 case), and Yanqing District (1 case). The anti-Leishmania antibody testing was all negative in 73 human blood samples and the sero-prevalence of anti-Leishmania antibody was 25.00% in 36 venous blood samples from domestic dogs in 2021, with a total of 4 520 Phlebotomus chinensis captured. The sero-prevalence of anti-Leishmania antibody was 0.51% in 198 human blood samples and 13.58% in 243 venous blood samples from domestic dogs in 2023, with 16.10%, 25.00%, 17.78% and 3.13% sero-prevalence in dogs sampled from Mentougou District, Changping District, Yanqing District and Haidian District, respectively (P = 0.011), while a total of 1 712 Ph. chinensis were captured, including 1 421 female sandflies (86.54%). CONCLUSIONS: The prevalence of local visceral leishmaniasis was low in Beijing Municipality from 2021 to 2023; however, there is a risk of further spread in the epidemic foci. Intensified visceral leishmaniasis surveillance and control is recommended.