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Biomedical subjects

Jorge Alvar

Publications and source records attributed to Jorge Alvar.

16 recordsLinked to original sources
PubMed2006

Leishmaniasis and poverty.

Leishmaniasis, a neglected tropical disease, has strong but complex links with poverty. The burden of leishmaniasis falls disproportionately on the poorest segments of the global population. Within endemic areas, increased infection risk is mediated through poor housing conditions and environmental sanitation, lack of personal protective measures and economically driven migration and employment that bring nonimmune hosts into contact with infected sand flies. Poverty is associated with poor nutrition and other infectious diseases, which increase the risk that a person (once infected) will progress to the clinically manifested disease. Lack of healthcare access causes delays in appropriate diagnosis and treatment and accentuates leishmaniasis morbidity and mortality, particularly in women. Leishmaniasis diagnosis and treatment are expensive and families must sell assets and take loans to pay for care, leading to further impoverishment and reinforcement of the vicious cycle of disease and poverty. Public investment in treatment and control would decrease the leishmaniasis disease burden and help to alleviate poverty.

Animals↗
PubMed2006

Liposomal amphotericin B for the treatment of visceral leishmaniasis.

During the past decade, liposomal amphotericin B has been used with increasing frequency to treat visceral leishmaniasis (VL). The World Health Organization convened a workshop to review current knowledge and to develop guidelines for liposomal amphotericin B use for VL. In Europe, liposomal amphotericin B is widely used to treat VL. In Africa and Asia, the VL disease burden is high and drug access is poor; liposomal amphotericin B is available only through preferential pricing for nonprofit groups in East Africa. Clinical trials and experience demonstrate high efficacy and low toxicity for liposomal amphotericin B (total dose, 20 mg/kg) in immunocompetent patients with VL. Combination trials in areas with antileishmanial drug resistance, and treatment and secondary prophylaxis trials in VL-human immunodeficiency virus-coinfected patients, are important to safeguard the current armamentarium and to optimize regimens. The public health community should work to broaden access to preferential liposomal amphotericin B pricing by public sector VL treatment programs.

AIDS-Related Opportunistic Infections↗
PubMed2006

Chemotherapy in the treatment and control of leishmaniasis.

Drugs remain the most important tool for the treatment and control of both visceral and cutaneous leishmaniasis. Although there have been several advances in the past decade, with the introduction of new therapies by liposomal amphotericin, oral miltefosine and paromomycin (PM), these are not ideal drugs, and improved shorter duration, less toxic and cheaper therapies are required. Treatments for complex forms of leishmaniasis and HIV co-infections are inadequate. In addition, full deployment of drugs in treatment and control requires defined strategies, which can also prevent or delay the development of drug resistance.

Animals↗
PubMed2006

Comparison of new diagnostic tools for management of pediatric Mediterranean visceral leishmaniasis.

New techniques are available for diagnosing leishmaniasis, but their efficacy in the identification of pediatric visceral leishmaniasis (VL) has not been compared with that of traditional methods. Blood, bone marrow, and urine samples were taken from 25 children with VL during their first clinical episode, 22 days after the start of treatment with liposomal amphotericin B (3 mg/kg/day on 6 days over a 10-day period), and when a relapse was suspected during follow-up. The results obtained suggest that antibody detection techniques, the antigen detection in urine (KAtex kit), and Leishmania nested PCR (LnPCR) analysis of the blood could be used for diagnosis of the first clinical episode. After treatment, clinical improvement was associated with negativization of Novy-MacNeal-Nicolle culture and microscopy of bone marrow aspirate, KAtex test, and LnPCR blood analysis results. Interestingly, LnPCR analysis of the bone marrow aspirate showed that sterile cure was not achieved in eight patients, two of which suffered a relapse within 10 to 20 weeks. All of the new noninvasive techniques tested showed high diagnostic sensitivity. However, LnPCR analysis of the bone marrow was the most sensitive; this test was able to detect the persistence of parasites and predict potential relapses.

Amphotericin B↗
PubMed2006

Leishmania/HIV co-infections in the second decade.

Leishmania-HIV co-infection has been globally controlled in Southern Europe since 1997 because of highly active anti retroviral therapy (HAART), but it appears to be an increasing problem in other countries such as Ethopia, Sudan, Brazil or India where both infections are becoming more and more prevalent. Most of the scientific background on Leishmania/HIV co-infection has been dropped from the Mediterranean experience and although the situations among countries are not fully comparable, it is of high importance to take advantage of this knowledge. In this review several aspects of the Leishmania/HIV co-infection are emphasized viz., epidemiological features, new ways of transmission, pathogenesis, clinical outcome, diagnosis, treatment and secondary prohylaxis. An extensive review of the literature on Leishmania/HIV co-infection has allowed the inclusion of a comprehensive and updated list of bibliographical references.

AIDS-Related Opportunistic Infections↗
PubMed2005

Semi-quantitative analysis of cytokine expression in asymptomatic canine leishmaniasis.

The dog is the main reservoir of Leishmania infantum, the parasite responsible for visceral leishmaniasis in Mediterranean countries. The infection in dogs shows different clinical presentations, from subclinical/asymptomatic to a fully developed disease, depending on the host's immune responses. The Th1/Th2 dichotomy is not clear in the different forms of canine leishmaniasis, since the data available from studies of immunity response in canine leishmaniasis are scarce and fragmented. The present work describes the cytokine expression in peripheral blood mononuclear cells (PBMC) obtained from asymptomatic dogs experimentally infected with L. infantum that present a cellular protective immune response. The results obtained from freshly isolated PBMC showed expressions of TNF-alpha, IL-2, IFN-gamma, IL-10 and IL-18 mRNA, similar to those from non-infected dogs. However, there was almost no expression of IL-4 mRNA detected in the asymptomatic infected dogs compared to the control dogs. Unspecific stimulation with ConA promoted the expression in a greater or lower degree of all the cytokines studied. In vitro stimulation of PBMC with soluble leishmanial antigen (SLA) promoted the expression of IL-2, IFN-gamma, TNF-alpha, IL-18, IL-4, IL-6 and IL-10 mRNA, with the two first being specifically induced. Although both Th1 and Th2 cytokines are produced, cell mediated immunity observed in these L. infantum-infected asymptomatic dogs depended on the preferential expression of Th1 cytokines.

Animals↗
PubMed2004

Amphotericin B lipid complex versus no treatment in the secondary prophylaxis of visceral leishmaniasis in HIV-infected patients.

OBJECTIVES: Visceral leishmaniasis (VL) in HIV-positive patients is characterized by a chronic course with frequent relapse. The aim of this study was to evaluate the efficacy and safety of amphotericin B lipid complex (ABLC) in preventing VL relapses in HIV-infected patients. METHODS: This was a multicentre, open-label (with blinded centralized randomization), parallel, no-treatment, controlled clinical trial. HIV-infected patients, with at least one previous treated episode of VL and with negative bone marrow aspirate for Leishmania parasites prior to the study, were randomized to receive either ABLC 3 mg/kg/day every 21 days (ABLC) or no treatment (NT). Patients were followed-up every 9 weeks for up to 12 months, and the efficacy was measured as the proportion of patients remaining free (non-relapse) of VL at 1 year of follow-up. The primary analysis was performed on an intention-to-treat basis. RESULTS: One hundred and fifteen patients were screened, but only 17 were randomized: eight in the ABLC group and nine in the NT group. The intention-to-treat analysis of data showed 50% of patients remaining free of VL at 12 months of follow-up (95% CI = 15.7%, 84.3%) in the ABLC group, and 22.2% (95% CI = 2.8%, 60.0%) in the NT group. The non-relapse odds ratio was 3.5 (95% CI = 0.30%, 52.0%) favouring ABLC. ABLC was well tolerated: patients only presented infusion-related mild adverse events. No patients from either group discontinued treatment or died during follow-up. CONCLUSIONS: ABLC, administered every 21 days for 12 months, is useful as secondary prophylaxis in preventing VL relapse in HIV-infected patients, and is well tolerated.

Adult↗
PubMed2004

Canine leishmaniasis.

Canine leishmaniasis is caused by Leishmania infantum (syn. L. chagasi, in America) and is transmitted by the bite of phlebotomine sand flies. Infected dogs constitute the main domestic reservoir of the parasite and play a key role in transmission to humans, in which the parasite produces visceral leishmaniasis. The increasing awareness that control of the human disease depends on effective control of canine leishmaniasis has promoted, in the last few years, research into leishmanial infection in dogs. Newly available specific reagents and molecular tools have been applied to the detailed investigation of canine leishmaniasis and important advances have been made in elucidating the epidemiology and pathology of the disease. These new findings have led to better understanding of the disease, and have also helped in the development of new diagnostic methods and control measures against the infection, such as insecticide-impregnated collars for dogs, new drugs and treatment protocols, and second generation vaccines, with the hope of not only reducing the heavy burden of the disease among dogs but also reducing the incidence of human visceral leishmaniasis.

Animals↗
PubMed2003

Amphotericin B lipid complex versus meglumine antimoniate in the treatment of visceral leishmaniasis in patients infected with HIV: a randomized pilot study.

Optimal treatment for HIV-related visceral leishmaniasis (VL) has still to be established. A pilot clinical trial was carried out in 57 HIV-VL coinfected patients to compare the efficacy and safety of amphotericin B lipid complex (ABLC) versus meglumine antimoniate. The patients were randomized to receive either ABLC 3 mg/kg/day for 5 days (ABLC-5, 18 patients), ABLC 3 mg/kg/day for 10 days (ABLC-10, 20 patients) or meglumine antimoniate 20 mg Sbv /kg/day for 28 days (19 patients). Treatment was considered successful if parasites were not detected in a bone marrow aspirate after treatment. Parasitological cure was attained in 33% (95% CI: 13%-59%) of the ABLC-5 group, in 42% (95% CI: 16%-62%) of the ABLC-10 group and in 37% (95% CI: 16%-62%) of the meglumine antimoniate group (P = 0.94). Eight out of 19 patients administered antimoniate discontinued treatment prematurely following serious adverse events, compared with one in the ABLC groups (P = 0.0006). The efficacy of ABLC is similar to meglumine antimoniate, but the severity of toxicity in the treatment of HIV-VL is lower with ABLC.

Adult↗
PubMed2003

[Antiparasite therapy].

The lack of any parasite vaccine makes prevention against parasitic diseases to be based, as in the past, in ecological measures such as the environmental health and vector control to interrupt the biological cycle; on the other hand, it is also based in anti-parasite drugs. Once the disease has been acquired it is just possible to take medication. Studies on the way of action allow to understand more about the physiology of the parasite and, on the other hand, to understand better the physiology of the parasite allows to design new more effective drugs. However, the vast majority of these new drugs have been obtained thanks to intelligent and selective screening of generic molecules more than from the result of the knowledge of the biochemistry of the parasite. Despite all this, it is well known the mechanisms of action of many antiparasite drugs which have led us, when possible, to the discussion about possible targets to give an idea of how the rational approximation to design new medicaments is done.

Antiparasitic Agents↗
PubMed2002

Evidence for a wide occurrence of proton-translocating pyrophosphatase genes in parasitic and free-living protozoa.

Proton-translocating inorganic pyrophosphatases (H(+)-PPase, EC 3.6.1.1) are integral membrane proteins that have been extensively studied in higher plants, the photosynthetic bacterium Rhodospirillum rubrum and, more recently, in some human pathogenic protozoa. By using a PCR-based approach, fragments of genes coding for H(+)-PPases in a number of protists, both free-living and parasites of animals and plants, that belong to diverse taxonomic groups (trypanosomatids, ciliates, apicomplexans, euglenoids, amoeboid mycetozoa, heterokonts) have been isolated. The experimental procedure involved the use of degenerate oligonucleotides designed from protein domains conserved in H(+)-PPases from plants and bacteria. The PCR-amplified DNA fragments exhibited the characteristic genomic structure and codon usage of the corresponding protozoan group. Paralogous genes were found in some species suggesting the occurrence of protein isoforms. These results indicate that H(+)-PPases are more widely distributed among protozoa than previously thought.

Amino Acid Sequence↗
PubMed2002

Relapses versus reinfections in patients coinfected with Leishmania infantum and human immunodeficiency virus type 1.

In the Mediterranean basin, Leishmania infantum is a major opportunistic parasite in people with acquired immunodeficiency syndrome (AIDS), and up to 9% of the patients with AIDS suffer from newly acquired or reactivated visceral leishmaniasis. Distinguishing between reinfections and relapses in these patients is important because some apparent treatment failures occur in patients with new rather than reactivated infections. Isoenzyme characterization is limited for use in determining relapsed versus newly acquired leishmaniasis in human immunodeficiency virus (HIV)-infected patients because of the variability of L. infantum and the predominance of the MON-1 zymodeme in people coinfected with HIV. A seminested polymerase chain reaction (PCR) was used to amplify L. infantum minicircle kinetoplast DNA, and, after digestion, the restriction fragment-length polymorphism (RFLP) profiles showed that 3 (7.5%) of 40 patients coinfected with L. infantum and HIV had a new infection, whereas isoenzyme characterization indicated that all 40 patients had infection relapses. These results suggest the utility of this PCR-RFLP analysis in detecting leishmaniasis reinfection in HIV-positive patients.

Animals↗
PubMed2002

Isolation and characterization of Leishmania infantum cDNA encoding a protein homologous to eukaryotic elongation factor 1 gamma.

This paper reports the isolation and characterization of a complementary deoxyribonucleic acid clone showing sequence homology with genes coding for the eukaryotic elongation factor 1 gamma (EF-1 gamma). The clone encodes an open reading frame of 404 amino acids corresponding to a deduced molecular mass of 46.2 kDa. Database searches revealed 30-64% sequence identity between the Leishmania infantum EF-1 gamma and several eukaryotic homologues. Southern blot analysis indicated that 2 genes tandemly organized were present in the L. infantum genome. The 3' untranslated regions of these 2 genes differed in size. Southern hybridization and pulsed field gel electrophoresis showed that EF-1 gamma genes are highly conserved among members of the Leishmania genus and must be clustered in a single chromosomal locus.

Amino Acid Sequence↗
PubMed2002

Canine leishmaniasis: epidemiological risk and the experimental model.

Increasing risk factors are making zoonotic visceral leishmaniasis a growing public health concern in many countries. Domestic dogs constitute the main reservoir of Leishmania infantum and Leishmania chagasi, and play a key role in the transmission to humans. New reagents and tools allow the detailed investigation of canine leishmaniasis, permitting the monitoring of the immunological status of dogs in both natural and experimental infections. Such studies are essential to determine the basis of the canine protective immune response and to establish a laboratory model, a significant aspect for the development of vaccines against canine leishmaniasis.

Animals↗