Viscerotropic Leishmaniasis Research Articles

Dogs may carry Leishmania tropica and Leishmania major in their blood circulation: a molecular and hematological study

BackgroundDogs may be infected with species of Leishmania parasites that are disseminated through blood circulation and invade the internal organs. In this study, we aim to detect the parasite in the blood of dogs using the PCR technique. The present work was performed from February 2022 to May 2023 in Fars Province, southern Iran, where the disease is endemic.ResultsIn total, 7(5.1%) out of 135 blood samples, six were identified as Leishmania tropica and one as Leishmania major. We found no trace of Leishmania infantum, which is always known for visceral infection. In addition, no sign of cutaneous lesions or a significant disease was seen in the animals infected with both species. Of 48 dogs with anemia, two were Leishmania positive. The mean value of hematological parameters in the infected dogs was within the normal range except for a significant reduction in the platelet measures (p < 0.05).ConclusionsOur data revealed that both Leishmania species, tropica and major, may manifest as viscerotropic leishmaniasis. More investigations are needed to understand the conditions under which these species choose the type of infection. Moreover, our data emphasize the role of asymptomatic dogs in carrying these parasites, a crucial factor in spreading the disease.

Viscerotropic Leishmaniasis; Diagnosis and species detection using the polymerase chain reaction with kinetoplast DNA-specific primers in Balb/c mice

The study involves three groups of Balb/c mice, the first and second groups inoculated in the hind footpad (1 x 106), (3 x 106) stationary phase promastigotes of L. tropica respectively, the third group inoculated phosphate buffer saline. The aim of this study was to establish a murine model for human viscerotropic leishmaniasis, and the dissemination of L. tropica to visceral organs tissues of BALB/c mice in order to find out the ability to diagnosis the disease by polymerase chain reaction (PCR) as recent application. The samples of liver tissues were collected and DNA was extracted by Promega DNA kit purification. The polymerase chain reaction (PCR) with kDNA specific primers was used firstly to distinguish the species of parasite which isolate from patient had cutaneous lesion acquired in Iraq where only L. major and L. tropica were expected to be the causative agents. The size difference between the PCR products of L. major and L. tropica allowed differential diagnosis. The smaller product (650 bp) could be identified as derived from L. major, whereas the larger product (800 bp) was due either to L. tropica or to a member of the L. donovani complex which yielded the same size of band. The same primers were used to detect the dissemination of parasites to visceral organs via extracted DNA from liver tissues of infected animals. PCR application was very high sensitive and early diagnosis in liver tissues as a substrate for PCR reaction, all animals of group (1) which infected with (106) promastigotes were negative result at (15) days post-infection, whereas three animals from group (2) which infected with (3x106) promastigotes showed positive result at the same period. All animals except one from group (1) showed positive results at (30) days post-infection. But at the later sequences days all animals were positive.

Leishmania tropica: suggestive evidences for the effect of infectious dose on pathogenicity and immunogenicity in an experimental model

Leishmania (L.) tropica is a causative agent of cutaneous and occasionally visceral or viscerotropic leishmaniasis in humans. The dose of parasites influences the course and outcome of disease in some Leishmania species. The effect of parasite dose on L. tropica infection in an experimental model was studied in the current paper. High and low doses of L. tropica were used for ear infection of BALB/c mice and lesion development, parasite load, and cytokine responses were assessed. L. major infection was used for comparison. Pre-infected mice were challenged in the footpad by a fixed high dose of L. tropica, and immune response and protection level were evaluated. High dose L. tropica infection in comparison to low dose results in higher lesion diameters, higher load of parasite in draining lymph node, higher levels of interferon-γ and interleukin-10, dissemination of parasite to spleen, and induction of protection against further L. tropica challenge. Comparison of L. tropica with L. major showed that L. tropica results in lower lesion diameters, more potential for growth in lymph nodes at early phases of infection, parasite dissemination to spleen, lower levels of IL-10, and a permanent lower cytokine response against low parasite dose in comparison to high dose. Our findings suggest that for L. tropica infection, only the high dose results in visceralization of the parasite and protection against further challenge of L. tropica. Therefore, the parasite dose may be an important factor in pathogenesis and immunity in L. tropica infection.

Viscerotropic leishmaniasis: a systematic review of the case reports to highlight spectrum of the infection in endemic countries

AbstractVisceral leishmaniasis is an important neglected parasitic disease that is generally caused byLeishmania infantum,Leishmania donovaniandLeishmania chagasi. However, several causative species of cutaneous leishmaniasis (CL) causes an interstitial form of leishmaniasis which known viscerotropic leishmaniasis. The aim of this paper is a systematic review of the cases of viscerotropic leishmaniasis to present the main causative agents, clinical manifestations, treatment and outcomes of the cases. An electronic search (any date to August 2017) without language restrictions was performed using Medline, PubMed, Scopus and Google Scholar. The searches identified 19 articles with total 30 case reports. Of them, old worldLeishmaniaspecies was reported from 23 (76.7%) cases, including 20 cases ofL. tropicaand three cases ofL. major; whereas new worldLeishmaniaspecies were reported in seven (23.4%) cases. The infection was more prevalent in male (24/30, 80%) than female (5/30, 16.7%) patients. Co-morbidity/co-infection was observed in 13 out of 30 cases (43.4%), which the most of them was HIV/AIDS (10 out of 13 cases, 76.9%). The results suggested that viscerotropic leishmaniasis should be more attended in the endemic countries of CL and in immunocompromised patients in order to exact discrimination from other endemic infectious diseases.

Comparative study of viscerotropic pathogenicity of Leishmania major amastigotes and promastigotes based on identification of mitochondrial and nucleus sequences.

Experimental viscerotropic leishmaniasis is regularly caused by Leishmania tropica promastigotes. In the current investigation, the viscerotropic pathogenicities of Leishmania major amastigotes and promastigotes were compared and evaluated based on their heterogeneity traits and number of inoculated parasites in experimental mammalian hosts. Serous exudate from 50 patients was infected, 44 with L. major and 6 with L. tropica; only BALB/c mice inoculated with 1-2 × 10(4-6) L. major amastigotes manifested cutaneous lesions at the base of their tails. Five out of the 44 BALB/c mice inoculated with L. major died of sequela of viscerotropic adverse effect, while 2 × 10(6) L. major promastigotes showed viscerotropic signs in four BALB/c mice. The sequencing of the Cyt b gene showed a strain of L. major (GenBank accession number KM393221: haplotype diversity 0.9) containing two codon mutations, 86 and 126 in dead mice, whereas no significant mutant was observed in internal transcribed spacer (ITS)-ribosomal DNA (rDNA) sequences (haplotype diversity 0). Findings show that a lower dose of L. major amastigotes than promastigotes has more potential viscerotropic intensity in susceptible hosts. It illustrates that testing Cyt b as an evolutionary mitognome marker because of having its semi-conserved structure and low copy number is able to be utilized in the discrimination of new mutants.

Immunomodulatory role of ATP inhibitor: glibenclamide and its impact on the pathogenesis of murine Leishmania major infection

Background Leishmania major is the causative agent of cutaneous leishmaniasis in humans. It can also induce visceral or viscerotropic systemic leishmaniasis in humans. Resistance to treatment has been reported in many countries. Glibenclamide (GB) has been found to enhance treatment in resistant cases. Aim The aim of this work was to study the immunomodulatory effect of ATP inhibitor-GB on leishmaniasis caused by L. major . Materials and methods Mice were divided into three groups: group I (GI), noninfected group; group II (GII), infected with L. major ; and group III (GIII), infected with L. major and treated with GB, starting 10 days postinfection till the end of the experiment. Evaluation was performed by measuring the size of cutaneous skin lesions, histopathological examination of the liver and spleen, and detection of expression of interferon γ, tumor necrosis factor α, interleukin (IL)-4, and IL-10 cytokines by reverse transcriptase real-time PCR. Transmission electron microscopic study of parasites from peritoneal exudate of GII and GIII mice was also carried out. Results The treated group showed a reduction in skin lesion size, improvement in histopathological manifestations, increased expression of interferon γ, and decreased tumor necrosis factor α, IL-4, and IL-10 expression. Transmission electron microscopic study showed vacuolation and damage of parasites in the treated group. Conclusion GB can be used effectively for the treatment of leishmaniasis.

Protective immunity against Leishmania major induced by Leishmania tropica infection of BALB/c mice

Leishmania (L.) tropica is a causative agent of human cutaneous and viscerotropic leishmaniasis. Immune response to L. tropica in humans and experimental animals are not well understood. We previously established that L. tropica infection induces partial protective immunity against subsequent challenge infection with Leishmania major in BALB/c mice. Aim of the present study was to study immunologic mechanisms of protective immunity induced by L. tropica infection, as a live parasite vaccine, in BALB/c mouse model. Mice were infected by L. tropica, and after establishment of the infection, they were challenged by L. major. Our findings shows that L. tropica infection resulted in protection against L. major challenge in BALB/c mice and this protective immunity is associated with: (1) a DTH response, (2) higher IFN-γ and lower IL-10 response at one week post-challenge, (3) lower percentage of CD4+ lymphocyte at one month post-challenge, and (4) the source of IFN-γ and IL-10 were mainly CD4− lymphocyte up to one month post-challenge suggesting that CD4− lymphocytes may be responsible for protection induced by L. tropica infection in the studied intervals.

Leishmania tropica–Induced Cutaneous and Presumptive Concomitant Viscerotropic Leishmaniasis With Prolonged Incubation

Leishmaniasis includes a spectrum of diseases caused by protozoan parasites belonging to the genus Leishmania. The disease is traditionally classified into visceral, cutaneous, or mucocutaneous leishmaniasis, depending on clinical characteristics as well as the species involved. Leishmania tropica is one of the causative agents of cutaneous leishmaniasis, with a typical incubation period of weeks to months. Observation We describe a 17-year-old Afghani girl who had lived in the United States for 4 years and who presented with a 6-month history of pretibial ulcerations, 9.1-kg weight loss, abdominal pain, splenomegaly, and extreme fatigue. Histopathologic examination and culture with isoenzyme electrophoresis speciation of her skin lesions confirmed the presence of L tropica. In addition, results of serum laboratory and serological studies were highly suggestive of concomitant visceral involvement. The patient was treated with a 28-day course of intravenous pentavalent antimonial compound sodium stibogluconate with complete resolution of her systemic signs and symptoms and improvement of her pretibial ulcerations. This is an exceptional case in that our patient presented with disease after an incubation period of years rather than the more typical weeks to months. In addition, this patient had confirmed cutaneous involvement, as well as strong evidence of viscerotropic disease caused by L tropica, a species that characteristically displays dermotropism, not viscerotropism.

Viscerotropic growth pattern of Leishmania tropica in BALB/c mice is suggestive of a murine model for human viscerotropic leishmaniasis

Leishmania (L.) tropica is a causative agent of cutaneous leishmaniasis, and occasionally of visceral or viscerotropic leishmaniasis in humans. Murine models of Leishmania infection have been proven to be useful for elucidation of mechanisms for pathogenesis and immunity in leishmaniasis. The aim of this study was to establish a murine model for human viscerotropic leishmaniasis, and the growth pattern of L. tropica was studied in different tissues of BALB/c mice in order to find out whether the parasite visceralizes in this murine model. L. major was used as a control as this species is known to cause a progressive infection in BALB/c mice. L. tropica or L. major was injected into the footpad of mice, and thickness of footpad, parasite loads in different tissues, and the weight of the spleen and lymph node were determined at different intervals. Results showed that L. tropica visceralizes to the spleen and grows there while its growth is controlled in footpad tissues. Dissemination of L. tropica to visceral organs in BALB/c mice was similar to the growth patterns of this parasite in human viscerotropic leishmaniasis. The BALB/c model of L. tropica infection may be considered as a good experimental model for human diseases.

Prevalence of symptoms and symptom-based conditions among Gulf War veterans: current status of research findings.

Shortly after the end of the Gulf War in March 1991, media reports began to emerge that veterans were experiencing a variety of medically unexplained symptoms, including fatigue, headache, aches and pains, and cognitive disturbances. In January 1992, the press reported an “outbreak” of unexplained symptoms among members of the 123rd Army Reserve Unit in Indiana. Soon, other veterans reported similar symptoms, and public concern grew regarding a “mystery illness” or “Gulf War syndrome.” Subsequent investigation of the reserve unit found no evidence for an outbreak of a unique disease (1). Although, well-defined diseases have been identified among some Gulf War veterans (e.g., 12 cases of viscerotropic leishmaniasis) (2), a substantial proportion of Gulf War veterans’ health complaints involves nonspecific symptoms, which are not readily explained medically.

Endemic infectious diseases and biological warfare during the Gulf War: a decade of analysis and final concerns.

Infectious diseases were one of the first health threats confronted by Coalition troops deployed to the Arabian desert in August 1990. On the basis of experiences in World War II, the major endemic infectious disease risks were thought to be sandfly fever, cutaneous leishmaniasis, diarrheal disease, and malaria. Although there was active surveillance, no case of sandfly fever and few other endemic infectious diseases were identified among over 500,000 U.S., British, and Canadian ground troops. In addition, there was no diagnosis of biological warfare (BW) exposure, and BW agents were not detected in clinical, environmental, or veterinary samples. The most common infectious disease problems were those associated with crowding (acute upper respiratory infections) and reduced levels of sanitation (travelers-type diarrhea). Only one endemic infectious disease has been confirmed as causing chronic health problems: visceral Leishmania tropica infection (viscerotropic leishmaniasis). However, this protozoan infection was diagnosed in only 12 U.S. veterans, and no new cases have been identified during the last 8 years. Infectious diseases were not a serious problem for Gulf War troops because of extensive preventive medicine efforts and favorable weather and geographic factors. Moreover, it is unlikely that an endemic infectious disease or a BW agent could cause chronic health problems and remain undetected over a 10-year period.

A Comprehensive Clinical Evaluation of 20,000 Persian Gulf War Veterans

In response to the health concerns of Gulf War veterans, the Department of Defense instituted the Comprehensive Clinical Evaluation Program (CCEP). Although not designed as a research study, the CCEP provided valuable clinical data. An analysis was conducted of CCEP findings from systematic and comprehensive examinations of 20,000 U.S. Gulf War veterans. Among 20,000 participants, the types of primary and secondary diagnoses varied widely. Also, among veterans with an ICD-9-CM diagnosis of "symptoms, signs, and ill-defined conditions," no single subcategory of illness predominated, and no characteristic physical sign or laboratory abnormality was identified. In-total, there were 74 (0.4%) cases of connective tissue disease; 52 (0.3%) noncutaneous malignancies; 42 (0.2%) peripheral neuropathies; 14 (0.07%) cases of interstitial pulmonary fibrosis; 12 (0.06%) cases of renal insufficiency; and no new cases of viscerotropic leishmaniasis. No clinical indication of a new or unique illness was identified in this self-referred population, and the types of physiologic disease that could result from postulated hazardous wartime exposures were uncommon.

Characterization of a Leishmania tropica antigen that detects immune responses in Desert Storm viscerotropic leishmaniasis patients.

A chronic debilitating parasitic infection, viscerotropic leishmaniasis (VTL), has been described in Operation Desert Storm veterans. Diagnosis of this disease, caused by Leishmania tropica, has been difficult due to low or absent specific immune responses in traditional assays. We report the cloning and characterization of two genomic fragments encoding portions of a single 210-kDa L. tropica protein useful for the diagnosis of VTL in U.S. military personnel. The recombinant proteins encoded by these fragments, recombinant (r) Lt-1 and rLt-2, contain a 33-amino acid repeat that reacts with sera from Desert Storm VTL patients and with sera from L. tropica-infected patients with cutaneous leishmaniasis. Antibody reactivities to rLt-1 indicated a bias toward IgG2 in VTL patient sera. Peripheral blood mononuclear cells from VTL patients produced interferon gamma, but not interleukin 4 or 10, in response to rLt-1. No cytokine production was observed in response to parasite lysate. The results indicate that specific leishmanial antigens may be used to detect immune responses in VTL patients with chronic infections.

Epidemiology of the Leishmaniases

The leishmaniases are a group of zoonotic infections caused by protozoan parasites of the genus Leishmania. These infections produce a variety of different clinical diseases depending on the virulence or tropism of the parasite and differential host immune responses. Newly recognized clinical presentations, such as viscerotropic leishmaniasis in American military veterans of Operation Desert Storm, continue to challenge clinicians. Epidemics of classic visceral leishmaniasis leading to thousands of deaths are ongoing in Brazil, India, and the Sudan. Epidemics of localized cutaneous leishmaniasis are ongoing in many areas of South America, North Africa, and Central Asia. A marked increase in cases is often associated with an influx of nonimmune populations into newly cleared agricultural populations into newly cleared agricultural areas or population expansion into previously unsettled areas surrounding cities. The emergence of leishmaniasis as an important opportunistic infection in AIDS patients portends an ominous future as the HIV pandemic sweeps into the hyperendemic areas of South America, Africa, and the Indian subcontinent. Parenteral transmission via needle sharing in HIV coinfected individuals in Spain is an epidemiologically significant new mode of transmission. Finally, recent work has elucidated an enzootic transmission cycle involving L. mexicana in Texas.