One Health Approach to Leishmaniases: Understanding the Disease Dynamics through Diagnostic Tools.

Leishmaniases are zoonotic vector-borne diseases caused by protozoan parasites of the genus Leishmania that affect millions of people around the globe. There are various clinical manifestations, ranging from self-healing cutaneous lesions to potentially fatal visceral leishmaniasis, all of which are associated with different Leishmania species. Transmission of these parasites is complex due to the varying ecological relationships between human and/or animal reservoir hosts, parasites, and sand fly vectors. Moreover, vector-borne diseases like leishmaniases are intricately linked to environmental changes and socioeconomic risk factors, advocating the importance of the One Health approach to control these diseases. The development of an accurate, fast, and cost-effective diagnostic tool for leishmaniases is a priority, and the implementation of various control measures such as animal sentinel surveillance systems is needed to better detect, prevent, and respond to the (re-)emergence of leishmaniases.

Case Report: Combination Therapy with Liposomal Amphotericin B, N-Methyl Meglumine Antimoniate, and Pentamidine Isethionate for Disseminated Visceral Leishmaniasis in a Splenectomized Adult Patient.

In immunocompromised patients, visceral leishmaniasis (VL) can present with atypical clinical symptoms that include poor response to treatment. No optimal therapeutic regimen is available for such cases. In a splenectomized male patient, we observed a disseminated form of the disease in the liver, bone marrow, lymph nodes, and gastrointestinal tract. There was an apparent clinical improvement when he was initially treated with liposomal amphotericin B (L-AmB), but this was followed by a relapse involving severe clinical symptoms. He was finally treated successfully with a combination of L-AmB, meglumine antimoniate, and pentamidine isethionate. It is important to include asplenia as an immunosuppressive condition that induces exotic VL pathologies. In such cases, combination anti-Leishmania drug therapy should be considered.

Genetic variant strains of Leishmania (Viannia) braziliensis exhibit distinct biological behaviors.

A variety of clinical forms of American cutaneous leishmaniasis (ACL) caused by Leishmania braziliensis, as well as differing immune responses of patients, have been reported for an ACL focus in the state of Minas Gerais, Brazil. In addition, two genetic profiles of L. braziliensis have been described, of which one variant profile (hsp70-variant) has been associated with atypical lesions. We investigated the biological behavior of genetic variant strains of L. braziliensis isolated from patients with different clinical manifestations of ACL. Experimental infections were performed with golden hamsters for five L. braziliensis strains in standardized doses of 1 × 106 parasites per inocula. The characteristics of skin lesions, histopathological features, and parasite burden were independently analyzed at 30 and 60 days post-infection. The data revealed distinct patterns in the onset time of visible skin lesions as well as in lesion size and parasite burden among the strains. The extent and density of the inflammatory infiltrate differed among strains, although cellular composition of granulomas appeared similar. Multivariate analysis indicated the occurrence of two clusters: one comprising native strains (cluster 1) and one comprising the reference strain (cluster 2). Within cluster 1, the genetic variants of L. braziliensis did not group with the non-variant strain suggesting that the distinct patterns of biological behavior of these strains could be associated with the known genetic diversity previously described for them.

Hidden danger: Unexpected scenario in the vector-parasite dynamics of leishmaniases in the Brazil side of triple border (Argentina, Brazil and Paraguay).

Every year about 3 million tourists from around the world visit Brazil, Argentina and Paraguay´s triple border region where the Iguaçu Falls are located. Unfortunately, in recent years an increasing number of autochthonous canine and human visceral leishmaniasis (VL) cases have been reported. The parasite is Leishmania (Leishmania) infantum and it is transmitted by sand flies (Phlebotominae). To assess the risk factors favorable for the establishment and spread of potential vectors the Centers for Disease Control and Prevention light trap (CDC-light trap) collections were made in the Foz do Iguaçu (FI) and Santa Terezinha de Itaipu (STI) townships and along two transects between them. Our study determined the Phlebotominae fauna, the factors that affect the presence and abundance of Lutzomyia longipalpis and Nyssomyia whitmani, the presence of L. infantum in different sand fly species and which Leishmania species are present in this region. Lutzomyia longipalpis was the prevalent species and its distribution was related to the abundance of dogs. Leishmania infantum was found in Lu. longipalpis, Ny. whitmani, Ny. neivai and a Lutzomyia sp. All the results are discussed within the Stockholm Paradigm and focus on their importance in the elaboration of public health policies in international border areas. This region has all the properties of stable VL endemic foci that can serve as a source of the disease for neighboring municipalities, states and countries. Most of the urban areas of tropical America are propitious for Lu. longipalpis establishment and have large dog populations. Pan American Health Organization´s initiative in supporting the public health policies in the border areas of this study is crucial and laudable. However, if stakeholders do not act quickly in controlling VL in this region, the scenario will inevitable become worse. Moreover, L. (Viannia) braziliensis found in this study supports the need to develop public health policies to avoid the spread of cutaneous leishmaniasis. The consequences of socioeconomic attributes, boundaries and frontiers on the spread of diseases cannot be neglected. For an efficient control, it is essential that urban planning is articulated with the neighboring cities.

High Resolution Melting Analysis Targeting hsp70 as a Fast and Efficient Method for the Discrimination of Leishmania Species.

BACKGROUND: Protozoan parasites of the genus Leishmania cause a large spectrum of clinical manifestations known as Leishmaniases. These diseases are increasingly important public health problems in many countries both within and outside endemic regions. Thus, an accurate differential diagnosis is extremely relevant for understanding epidemiological profiles and for the administration of the best therapeutic protocol. METHODS/PRINCIPAL FINDINGS: Exploring the High Resolution Melting (HRM) dissociation profiles of two amplicons using real time polymerase chain reaction (real-time PCR) targeting heat-shock protein 70 coding gene (hsp70) revealed differences that allowed the discrimination of genomic DNA samples of eight Leishmania species found in the Americas, including Leishmania (Leishmania) infantum chagasi, L. (L.) amazonensis, L. (L.) mexicana, L. (Viannia) lainsoni, L. (V.) braziliensis, L. (V.) guyanensis, L. (V.) naiffi and L. (V.) shawi, and three species found in Eurasia and Africa, including L. (L.) tropica, L. (L.) donovani and L. (L.) major. In addition, we tested DNA samples obtained from standard promastigote culture, naturally infected phlebotomines, experimentally infected mice and clinical human samples to validate the proposed protocol. CONCLUSIONS/SIGNIFICANCE: HRM analysis of hsp70 amplicons is a fast and robust strategy that allowed for the detection and discrimination of all Leishmania species responsible for the Leishmaniases in Brazil and Eurasia/Africa with high sensitivity and accuracy. This method could detect less than one parasite per reaction, even in the presence of host DNA.

Vigilância da leishmaniose visceral em localidades epidemiologicamente distintas em Juruti, um município minerário do Estado do Pará, Brasil / Surveillance of visceral leishmaniasis in epidemiologically distinct locations in Juruti, a mining municipality in Pará State, Brazil

Realizaram-se ações de vigilância para leishmaniose visceral humana (LVH) em Juruti, município minerário do Estado do Pará. Foram selecionadas as localidades de Santa Maria (SM), periurbana, e Capiranga (CA), rural, com e sem LVH, respectivamente, para quatro inquéritos sorológicos semestrais (ELISA-Lisado) nas populações caninas (SM = 94; CA =45) e três levantamentos entomológicos (armadilhas luminosas CDC, 18-6hx4). Posteriormente, investigaram-se clínico e infecção por em 53 cães (SM = 28; CA = 25) com diagnóstico parasitológico (medula/linfa, Giemsa), molecular (leucócitos do sangue periférico, kDNA-PCR) e sorológico (ELISA), avaliando-se diferentes antígenos (Lisado, k39, Hsp83 - , curva ROC). Soroprevalências variaram em SM (45; 40; 15; 15 por cento) e CA (22; 30; 8,5; 0 por cento), com médias crescentes de IgG em SM(320; 378; 951; 1866; p<0,05), apesar da eutanásia de cães após segundo inquérito, e estáveis em CA (100; 159, 141; 0), onde não houve eutanásia. A frequência de spp diferiu em SM (279/296) e CA (4/6). Os resultados clínicos e laboratoriais assemelharam-se para cães de SM e CA, respectivamente, quanto à infecção (parasitológico: 86 e 84 por cento; kDNA-PCR: 100 por cento), clínico (assintomáticos: 43 e 56 por cneto; sintomáticos: 57 e 44 por cento) e especificidade no ELISA (100 por cento), mas variaram sensibilidades(Lisado: 44 e 18 por cento; Hsp83: 48 e 27 por cento; k39: 48 e 41 por cento) e níveis de IgG ( 6.400; 200). O perfil da infecção canina nas localidades com e sem transmissão de LVH diferiu apenas em níveis/evolução de IgG, o que torna necessária a temporalidade dos inquéritos, sobretudo em áreas silenciosas, isoladas com baixa densidade do vetor, onde seria dispensável a eutanásia de cães. O melhor teste sorológico foi ELISA-k39.

Surveillance actions for human visceral leishmaniasis (HVL) were carried out in Juruti, a mining municipality in Pará State. A peri-urban (Santa Maria-SM) and a rural (Capiranga-CA) location were selected with or without HVL, respectively, for the execution of four biannual serologic inquiries (lysate ELISA) in canine populations (SM = 94, CA = 45) and three entomological surveys (CDC light traps, 18-6 h x4). Subsequently, the clinical status, as well as the infection by leishmania , was investigated in 53 dogs (SM = 28; CA = 25) with parasitological (bone marrow/lymph, Giemsa), molecular(peripheral blood leukocytes, kDNA-PCR) and serological (ELISA) diagnoses assessing different antigens (lysate, k39, Hsp83 - screen test, ROC curve). Seroprevalence varied in SM (45; 40; 15; 15 percent) and in CA (22; 30; 8.5; 0 percent), presenting increasing average IgG rates in SM (320; 378; 951; 1866; p <0.05) despite the euthanasia of dogs after the second survey, and stable average IgG rates in CA (100; 159; 141; 0), where euthanasia was not conducted. The frequency rates of lutzomyia longpalpis/Lutzomia spp. differed in SM (279/296) and CA (4/6). Clinical and laboratory results were similar for dogs from SM and CA, respectively: infection (parasitological examination: 86 and 84 percent; kDNA-PCR: 100 percent), clinical status (asymptomatic: 43 and 56 percent; symptomatic: 57 and 44 percent), and specificity by ELISA (100 percent). On the other hand, sensitivity (lysate: 44 and 18 percent; Hsp83: 48 and 27 percent; k39: 48 and 41 percent) and IgG levels ( 6,400; 200) varied, respectively. The profile of canine infection in localities with or without HVL transmission differed only in terms of the level/evolution of IgG, which makes the temporality of investigations necessary, especially in quiet and isolated areas that present a low vector density and where the euthanasia of dogs would become unnecessary. The best serological test was ELISA-k39.

Etiology of cutaneous leishmaniasis and anthropophilic vectors in Juruti, Pará State, Brazil.

In a preliminary study in Juruti, a mining municipality in western Pará State, Brazil, 12 out of 21 patients suspected of presenting cutaneous leishmaniasis showed positive PCR (SSUrDNA and G6PD): Leishmania (Viannia) braziliensis (9/12; 75%) and L. (V.) sp. (3/12; 25%). Entomological studies in the same location revealed the presence of 12 different phlebotomine species (n =105). One of the most common species was Lutzomyia (Psychodopygus) complexa (17%) which is both highly anthropophilic and a known vector of L. (V.) braziliensis in other regions of Pará. These preliminary findings should serve to guide future epidemiological surveillance in Juruti.

Etiology of cutaneous leishmaniasis and anthropophilic vectors in Juruti, Pará State, Brazil / Etiologia da leishmaniose cutânea e vetores antropofílicos em Juruti, Estado do Pará, Brasil

In a preliminary study in Juruti, a mining municipality in western Pará State, Brazil, 12 out of 21 patients suspected of presenting cutaneous leishmaniasis showed positive PCR (SSUrDNA and G6PD): Leishmania (Viannia) braziliensis (9/12; 75 percent) and L. (V.) sp. (3/12; 25 percent). Entomological studies in the same location revealed the presence of 12 different phlebotomine species (n =105). One of the most common species was Lutzomyia (Psychodopygus) complexa (17 percent) which is both highly anthropophilic and a known vector of L. (V.) braziliensis in other regions of Pará. These preliminary findings should serve to guide future epidemiological surveillance in Juruti.

Em um estudo preliminar em Juruti, um município minerário na região oeste do Estado do Pará, Brasil, 12 de 21 pacientes suspeitos de possuírem leishmaniose cutânea tiveram PCRs positivas (SSUrDNA e G6PD): Leishmania (Viannia) braziliensis (9/12; 75 por cento) e Leishmania (Viannia) sp. (3/12; 25 por cento). Estudos entomológicos na mesma localidade revelaram a presença de 12 diferentes espécies de flebotomíneos (n = 105). Uma das espécies mais comuns foi Lutzomyia (Psychodopygus) complexa (17 por cento) que é altamente antropofílica e reconhecida vetora de L. (V.) braziliensis em outras regiões do Estado do Pará. Esses resultados preliminares servem como orientação para futura vigilância epidemiológica em Juruti.

A real-time polymerase chain reaction assay for the identification and quantification of American Leishmania species on the basis of glucose-6-phosphate dehydrogenase.

A real-time polymerase chain reaction (PCR) test was developed on the basis of the Leishmania glucose-6-phosphate dehydrogenase locus that enables identification and quantification of parasites. Using two independent pairs of primers in SYBR-Green assays, the test identified etiologic agents of cutaneous leishmaniasis belonging to both subgenera, Leishmania (Viannia) and Leishmania (Leishmania) in the Americas. Furthermore, use of TaqMan probes enables distinction between L. (V.) braziliensis or L. (V.) peruviania from the other L. (Viannia) species. All assays were negative with DNA of related trypanosomatids, humans, and mice. The parasite burden was estimated by normalizing the number of organisms per total amount of DNA in the sample or per host glyceraldehyde-3-phosphate dehydrogenase copies. The real-time PCR assay for L. (Leishmania) subgenus showed a good linear correlation with quantification on the basis of a limiting dilution assay in experimentally infected mice. The test successfully identifies and quantifies Leishmania in human biopsy specimens and represents a new tool to study leishmaniasis.

New PCR assay using glucose-6-phosphate dehydrogenase for identification of Leishmania species.

Glucose-6-phosphate dehydrogenase (G6PD) is one of the multilocus enzymes used to identify Leishmania by zymodeme analysis. The polymorphic pattern revealed by partial characterization of the gene encoding G6PD generated molecular markers useful in the identification of different Leishmania species by PCR. Initially degenerate oligonucleotides were designed on the basis of data on the conserved active center described for other organisms. Primers for reverse transcription-PCR experiments, designed from the nucleotide sequence of the PCR product, enabled us to characterize the 5' and 3' untranslated regions and the G6PD open reading frame of reference strains of Leishmania (Viannia) braziliensis, Leishmania (Viannia) guyanensis, Leishmania (Leishmania) mexicana, and Leishmania (Leishmania) amazonensis. Sets of paired primers were designed and used in PCR assays to discriminate between the parasites responsible for tegumentar leishmaniasis of the subgenera Leishmania (Leishmania) and Leishmania (Viannia) and to distinguish L. (Viannia) braziliensis from others organisms of the subgenus Leishmania (Viannia). No amplification products were detected for the DNA of Crithidia fasciculata, Trypanosoma cruzi, or Leishmania (Sauroleishmania) tarentolae or DNA from a healthy human control. The tests proved to be specific and were sensitive enough to detect parasites in human biopsy specimens. The successful discrimination of L. (Viannia) braziliensis from other parasites of the subgenus Leishmania (Viannia) opens the way to epidemiological studies in areas where more than one species of the subgenus Leishmania (Viannia) exist, such as Amazonia, as well as follow-up studies after chemotherapy and assessment of clinical prognoses.