Visceral Leishmaniasis Control Program Research Articles

Detection of Leishmania infantum in 4 different dog samples by real-time PCR and ITS-1 nested PCR

The canine visceral leishmaniasis (CVL) diagnosis is an important step of visceral leishmaniasis control program in Brazil, which involves the elimination of infected dogs, the main animal reservoir host of the disease. The aim of the present study was to evaluate a sensitive real-time PCR method for Leishmania infantum detection in 4 different clinical samples of dogs, including the noninvasive conjunctival swab (CS) sample. The results of real-time PCR were compared with those obtained using internal transcribed spacer 1 nested PCR. Animals were divided into 2 groups based on the absence or presence of CVL clinical sings. The CS associated with real-time PCR, using primers addressed to kinetoplast DNA minicircles, was able to detect L. infantum infection in 96.7% of dogs without clinical signs and in 100% of the symptomatic animals, demonstrating the importance of these procedures for diagnosing CVL.

Factors associated with Leishmania chagasi infection in domestic dogs from Teresina, State of Piauí, Brazil

Many studies have evaluated risk factors for human visceral leishmaniasis, but few have focused on the infection among dogs. The objective of this study was to assess the association between peridomestic socioeconomic and environmental factors and the presence of dogs seropositive for Leishmania chagasi in the City of Teresina, Brazil. This case-control study was based on the results of a routine seroepidemiological survey among domestic dogs carried out in 2007. Serological tests were performed by means of indirect immunofluorescence antibody test. All dwellings in which at least one seropositive dog was detected were considered cases, and controls were a random sample of dwellings in which only seronegative dogs were identified. Associations between variables were expressed as odds ratios (OR) and their respective 95% confidence intervals (95%CI) estimated using multivariate logistic regression. Dwellings with a history of dogs removed by the visceral leishmaniasis control program in the last 12 months had five-fold higher odds of having at least one seropositive dog as compared with dwellings having no history of dog removal (OR = 5.19; 95%CI = 3.20-8.42). Dwellings with cats had 58% increased odds of dog infection as compared with those having no cats (OR = 1.58; 95%CI = 1.01-2.47). Identification of factors associated with canine visceral leishmaniasis might be used for the delimitation of areas of higher risk for human visceral leishmaniasis, since infection in dogs generally precedes the appearance of human cases.

Laboratory tests performed on Leishmania seroreactive dogs euthanized by the leishmaniasis control program

In 2008, in the west zone of Rio de Janeiro municipality—Brazil, the leishmaniasis control program identified 155 dogs with titers ≥40 by Indirect ImmunoFluorescence (IIF) on blood collected onto filter paper. The objective of this study was to describe the laboratory test findings performed in dogs euthanized by the leishmaniasis program control of Rio de Janeiro municipality. Dogs were examined, subjected to euthanasia and collection of clinical specimens. Parasite isolation was obtained in 29 animals: Leishmania chagasi was isolated in 14 dogs; Leishmania braziliensis was isolated in five dogs; Trypanosoma caninum was obtained in seven animals and one dog had mixed infection ( L. braziliensis and L. chagasi). By Polymerase Chain Reaction, seventeen animals were positive in intact skin fragments. In the serological reassessment of serum samples, 28% and 22% were positive for IIF and enzyme immunoassay, respectively. Ninety-one (59%) dogs were negative for all tests performed in this study. The findings indicate that the visceral leishmaniasis control program needs to be adjusted in order to avoid non-infected dogs from being removed or permit that dogs infected with L. chagasi to remain undetected in endemic areas.

Developments in the treatment of visceral leishmaniasis

Background: Visceral leishmaniasis (VL) is one of the most neglected parasitic diseases causing large scale mortality and morbidity among the poorest of the poor in the Indian subcontinent and Africa. Objective: This review aims to describe the potential and the (lack of) current impact of newly developed treatments on the control of VL. It describes how the problem of an empty research pipeline is addressed, and discusses the emerging threat of incurable HIV/VL coinfection. Methods: The literature was searched for drugs used in VL. Conclusion: Research and development of VL drugs has received a financial boost but no new drugs are expected in the next 5 years. Only three new and highly effective treatments have been licensed in the past 10 years. These remain, however, largely inaccessible as VL control programs in the developing world are lacking. This is deserving of immediate and urgent attention, especially in the context of the rapidly expanding HIV/VL coinfection.

Study of cross-reactivity in serum samples from dogs positive for Leishmania sp., Babesia canis and Ehrlichia canis in enzyme-linked immunosorbent assay and indirect fluorescent antibody test

To verify the presence of cross-reaction among leishmaniosis, ehrlichiosis and babesiosis in serological diagnostics used in human visceral leishmaniasis control programs, serum samples from leishmaniasis endemic and non-endemic areas were collected and tested by Indirect Fluorescent Antibody (IFAT) and Enzyme-linked immunosorbent assay (ELISA). All serum samples from endemic areas were positive for Leishmania sp., by ELISA and IFAT, 51% positive for Babesia canis and 43% for Ehrlichia canis by IFAT. None of the serum samples from non-endemic areas were positive for Leishmania sp., by IFAT, but 67% were positive for B. canis and 78% for E. canis using the same test. When tested by ELISA for Leishmania sp., four samples from non-endemic area were positive. These dogs were then located and no clinical signs, parasites or antibody was detected in new tests for a six month period. Only one of these 4 samples was positive for B. canis by IFAT and ELISA and three for E. canis by IFAT. The results of the work suggest a co-infection in the endemic area and no serological cross-reaction among these parasites by IFAT and ELISA.

The economic impact of visceral leishmaniasis on households in Bangladesh

To explore current patterns of diagnosis and treatment, quantify household economic impact and identify household strategies to cover the costs of visceral leishmaniasis (VL) care in rural Bangladesh. Structured interviews with 113 VL patients from 87 households documenting all provider visits and expenditures for health care for VL, and the ways in which the expenditures were covered. Patients paid a median of 7 visits to six different providers before beginning VL treatment. All visited the subdistrict government hospital at least once. While health care, including antileishmanial drug therapy, is officially available free of charge at government facilities, 79% of patients reported making informal payments for provider access, diagnostics and drug administration; only 14% of patients received their full drug course from this source. For the 58% of patients who purchased the full treatment course, drug cost constituted 34% of direct expenditure. Median direct expenditure for one VL patient was US$87 and median income lost was $40; median total expenditure was 1.2 times annual per capita income of our study population. Households employed multiple coping strategies to cover expenditures, most commonly sale or rental of assets (62%) and taking out loans (64%). Visceral leishmaniasis treatment causes a major economic burden in affected families. Control strategies for VL should facilitate timely, affordable diagnosis and treatment of patients to decrease the infection reservoir and to alleviate the economic burden of VL on households.