Domestic rats are the principal reservoir for urban leptospirosis. However, few studies have identified infestation markers in slums and evaluated their predictivity for leptospirosis risk. We compared households with leptospirosis cases in Salvador, Brazil between 2007 and 2009 and their neighbors using a case control design, surveying for rodent infestation signs and environmental characteristics. With the 2007–2008 data, a conditional logistic regression modeling identified the peridomiciliar presence of rodent burrows (OR, 3.30; 95% CI, 1.50–7.26), rat feces (2.86; 1.24–6.59), runs (2.57; 1.06–6.22), households bordering abandoned houses (2.48; 1.04–6.02), and unplastered walls (2.22; 1.02–6.02) as risk factors and developed a predictive score for leptospirosis. With an independent data set from 2009, a receiver operating characteristic (ROC) curve analysis evaluated the prediction score performance, with the area under the curve being 0.70 (95% CI, 0.64–0.76) for score development and 0.71 (0.65–0.79) for validation. Results indicate that high proportions of urban slum households are infested with R. norvegicus. The score performed well when identifying high-risk households within slums. These findings need confirmation in other urban centers, but suggest that community-based screening for rodent infestation can allow to target rodent and environmental control measures in populations at highest risk for leptospirosis.

Visceral leishmaniasis (VL) is a zoonosis of great importance. Limitations in current VL control measures compromise efficacy, indicating the need to implement new strategies. The aim of this study was to evaluate the effectiveness of the mass use of deltamethrin-impregnated collars in dogs as a public health measure to control and prevent canine visceral leishmaniasis (CVL). An interventional study was implemented in two endemic areas in the district of Monte Gordo (Bahia-Brazil): an intervention area, in which VL seronegative dogs were collared, and a control area in which only conventional CVL control measures were applied. At baseline, seropositive dogs were removed and seronegative dogs were included. Dogs were then reevaluated every 7–8 months for almost two years. At each time point, dogs in the intervention area that remained seronegative received new collars and newly identified seronegative dogs were included and collared. The local zoonosis control authorities were notified of any dogs that tested seropositive in both areas, which were subsequently marked for euthanasia as mandated by the Brazilian Ministry of Health. In the first serological survey, seroprevalence was similar in both areas. At the second evaluation, significant reductions in seroprevalence were seen in both areas, while seroprevalence in the intervention area reduced to 6.0% during the final evaluation versus an increase of 11.0% in the control area. This significant increase and the estimated relative risk (RR = 0.55) indicated protection against CVL in the intervention area. Although CVL incidence did not differ significantly between the areas, an increased tendency was observed in the control area, which could be due to low seroconversion rates throughout the study or a high loss to follow-up. Although our evaluation of the effectiveness of deltamethrin-impregnated collars as a community-wide public health control measure was inconclusive, this measure likely provides protection over time. In endemic areas of Brazil, this strategy represents an operational challenge for local zoonosis control authorities, indicating the need for adjustments, including improved collar design. Visceral leishmaniasis (VL) is a serious public health problem. Cases of canine VL (CVL) tend to precede cases of human VL and current control measures are ineffective in significantly reducing the number of disease cases. Therefore, in light of the need for new strategies, we evaluated the mass use of dog collars impregnated with deltamethrin as a public health measure to control and prevent CVL in a highly endemic region in Brazil. Although our results were inconclusive, they do point to the possible effectiveness of this measure if it were comprehensively implemented over an extended period of time. We identified the need to adjust the currently employed implementation strategy and call attention to the operational challenges faced by local zoonosis prevention authorities.

Visceral leishmaniasis is associated with a variety of hematological abnormalities. In this study, we correlated the hematological changes in the peripheral blood of dogs naturally infected with Leishmania infantum (L. infantum) with the distribution of cell lineages and cytokine gene expression patterns in the bone marrow. Samples from 63 naturally semidomiciled dogs living in an endemic area of visceral leishmaniasis were analyzed. L. infantum infection was detected in 50 dogs (79.3%). Among those, 18 (32%) had positive splenic cultures and showed more clinical signs. They also had lower red blood cell counts and leukocytosis with an increased number of neutrophils and monocytes in peripheral blood compared to dogs negative to this test. L. infantum DNA was detected in the bone marrow of 8/14 dogs with positive splenic culture. Dogs with L. infantum infection in the bone marrow presented with histiocytosis (p = 0.0046), fewer erythroid cell clusters (p = 0.0127) and increased gene expression levels of IFN-γ (p = 0.0015) and TNF (p = 0.0091). The data shown herein suggest that inflammatory and cytokine gene expression changes in bone marrow may contribute to the peripheral blood hematological changes observed in visceral leishmaniasis.

Visceral leishmaniasis (VL) is a serious public health challenge in Brazil and dogs are considered to be the main urban reservoir of the causative agent. The culling of animals to control VL in some countries makes the accurate diagnosis of canine VL (CVL) essential. Recombinant antigens rLci1A and rLci2B were selected from a cDNA library of Leishmania infantum amastigotes due to their strong potential as candidates in diagnostic testing for CVL. The present multicentric study aimed to evaluate the sensitivity of a prototype test using these antigens (DPP rLci1A/rLci2B) against 154 sera obtained from symptomatic dogs within three endemic areas of VL in Brazil. The specificity was evaluated using 40 serum samples from negative dogs and dogs infected with other pathogens. Sensitivity and specificity rates of DPP rLci1A/rLci2B prototype were compared to rates from other diagnostic tests currently in use by the Brazilian Ministry of Health, including DPP®LVC, EIE®LVC. DPP rLci1A/rLci2B prototype offered similar performance to that offered by DPP®LVC rapid test, as follows: sensitivity of 87% (CI 81–91) and 88% (CI 82–93) and specificity of 100% (CI 91–100) and 97% (CI 87–100), respectively for DPP rLci1A/rLci2B and DPP®LVC. When results of these two tests were considered concomitantly, sensitivity increased to 93.5% (CI 89–96). The recombinant antigens rLci1A and rLci2B represent promising candidates for use in a multi-antigen rapid test for CVL. The inclusion of novel antigens to the DPP rLci1A/rLci2B prototype model could offer additionally enhanced sensitivity to detect animals infected by L. infantum.

Visceral leishmaniasis (VL) is a zoonosis caused by the protozoan Leishmania infantum and in Brazil is transmitted mainly by the bite of Lutzomuyia longipalpis sand flies. Data about the presence, distribution, natural infection rate, seasonal and monthly dynamics of the vector population are important for optimizing the measures to control VL in endemic areas. This study aimed to identify sand fly fauna in an endemic area for VL to detect the prevalence of L. infantum infection in the Lu. longipalpis population and to elucidate the influence of bioclimatic factors on the monthly fluctuations of this vector. HP light traps were monthly set in the intradomicile and peridomicile of residences located in the central and beachfront areas of Camaçari, a VL endemic area. The sand fly collection was conducted in two periods: i) period 1—between December 2011 and November 2012 and ii) period 2—August 2014 and July 2015. Sand fly species were identified and detection of L. infantum infection by qPCR was performed in pools of female Lu. longipalpis. For the first time, the parasite load of positive pools was correlated with the number of Lu. longipalpis captured per month in both periods. Correlation analyses between the monthly fluctuation of the sand fly population and bioclimatic indices of the municipality in both collection periods were also performed. In both evaluated periods, more than 98% of the collected sand flies were Lu. longipalpis, confirming the predominance of this species in the region. It was captured mostly in the beachfront area in all months evaluated (99%). For the period 1, Leishmania DNA was detected in 81% of tested pools representing a minimal infection rate of 9.6%. In the period 2, 40% of the pools were positive with a minimal infection rate of 10.2%. Infected sand flies were only detected in the beachfront area in both periods. The parasite load was low and did not vary in the evaluated months despite the number of collected sand flies. No correlation was observed for climatic factors in both areas of Camaçari. These findings emphasize the high risk of Leishmania transmission in Camaçari regardless of the season and that other factors, aside from bioclimatic elements, are influencing the sand fly population monthly fluctuation. Visceral leishmaniasis (VL) is a parasitic disease transmited by a sand fly vector. VL is an important public health issue in Brazil occurring in all its regions with increasing incidences in big urban centers. In the State of Bahia, VL has spread to new hotspots in the last decade reaching the coastal area to the north of Bahia State capital, Salvador. This region underwent several environmental changes due to a rapid urbanization and construction of touristic and vacation complexes. Our investigation represents the first entomological study conducted in Camaçari. We evaluated the prevalence of the parasite infection in the sand fly population in two periods, between December 2011 and November 2012 and between August 2014 and July 2015. Our findings indicate that VL transmission occurs during the whole year and support the idea that the vector is not sensible to bioclimatic variations in Camaçari. Additionally, the maintenance of the parasite infection in the vector regardless of the season, indicates that the disease is well stablished in Camaçari, especially in the coastal area. These results emphasizes the urgency for a rigorous entomological and epidemiological survey aiming to guide control strategies to decrease VL cases.

Canine Visceral leishmaniasis (CVL) is a serious public health problem, thus for its control, the Ministry of Health in Brazil recommends the rapid diagnosis and euthanasia of seropositive dogs in endemic areas. Therefore, our group had previously selected six recombinant proteins (rLci1, rLci2, rLci4, rLci5, rLci8, and rLci12) due to their high potential for CVL diagnostic testing. The present study aims to produce an immunodiagnostic test using the aforementioned antigens, to improve the performance of the diagnosis of CVL recommended by Brazilian Ministry of Health. To evaluate the recombinant proteins in the serological assays, positive and negative samples were selected based on parasitological test (culture) and molecular test (qPCR) of splenic aspirate. Initially, we selected 135 dog serum samples, 73 positives (symptomatic and asymptomatic) and 62 negatives to screen recombinant proteins on ELISA platform. Then, for rLci5 ELISA validation, 361 serum samples collected in a cross-sectional study were selected, being 183 positives (symptomatic and asymptomatic) and 178 negatives. In the screening of the recombinant proteins, rLci5 was the only protein to present a performance statistically higher than the performance presented by EIE^-LVC test, presenting 96% (IC 95%; 85–99%) vs. 83% (IC 95%; 69–92%) of sensitivity for symptomatic dogs, 71% (IC 95%; 49–97%) vs. 54% (IC 95%; 33–74%) for asymptomatic dogs and 94% (IC 95%; 83–99%) vs, 88% (IC 95%; 76–95% of specificity. Thus, the rLci5 protein was selected to compose a final ELISA test. Validation of rLci5 ELISA showed 87% (IC 81–91%) of sensitivity, 94% (IC 95%; 90–97%) of specificity and 90% accuracy. Testing the EIE^-LVC with the same validation panel, we observed a lower performance when compared to ELISA rLci5 (sensitivity of 67% (IC 95%; 59–74%), specificity of 87% (IC 95%; 81–92%), and accuracy of 77%). Finally, the performance of current CVL diagnostic protocol recommended by Brazilian Ministry of Health, using DPP^-LVC as screening test and EIE^-LVC as confirmatory test, was compared with a modified protocol, replacing EIE^-LVC by rLci5 ELISA. The current protocol presented a sensitivity of 59% (IC 95%; 52–66%), specificity of 98% (IC 95%; 95–99%) and accuracy of 80% (IC 95%; 76–84%), while the modified protocol presented a sensitivity of 71% (IC 95%; 63–77%), specificity of 99% (IC 95%; 97–100%) and accuracy of 86% (IC 95%; 83–89%). Thus, we concluded that rLci5 ELISA is a promising test to replace EIE^-LVC test and increase the diagnostic performance of CVL in Brazil. Visceral leishmaniasis is a tropical disease caused by the protozoan parasite Leishmania infantum, which is transmitted to humans through the bite of infected sand flies. Infected dogs are considered the main urban reservoir of parasite. Identification and euthanasia of infected dogs is one of the main strategies for VL control recommended by the Brazilian Ministry of Health. Hence, to improve the efficacy of control measures, it is essential an accurate diagnose of naturally infected dogs in endemic areas. Herein, we sought to produce a new immunodiagnostic test using recombinant antigens of Leishmania infantum to improve the performance of the diagnosis of CVL recommended by Brazilian Ministry of Health.