First description of autochthonous canine visceral leishmaniasis in the metropolitan region of Vitória, State of Espírito Santo, Brazil

Detection of Leishmania (Viannia) braziliensis in bats from Espírito Santo, Brazil (2018-2019)

Studying the occurrence of Leishmania in bats would help toward clarifying the role of these animals in epidemiological cycles. Therefore, the objective of this study was to detect Leishmania spp. in bats from the Brazilian State of Espírito Santo. In total, 105 bats from 11 species which had been collected from 17 municipalities of Espírito Santo were obtained from the IDAF Rabies Diagnostic Laboratory between December 2018 and June 2019. DNA was extracted from the bone marrow, skin, and spleen samples and analysed using conventional PCR, with primers specific for the kinetoplastic DNA minicircle of the parasitic species Leishmania (Viannnia) braziliensis, Leishmania (Leishmania) infantum, and Leishmania (Leishmania) amazonensis. To identify the Leishmania species, the positive PCR products were analysed using PCR-RFLP with the HaeIII enzyme and 8% polyacrylamide gel electrophoresis. Positivity for L. (V.) braziliensis was observed in five (4.76%) bats: namely, one male Eumops glaucinus from Vitória (in a skin sample), one male Artibeus lituratus from Vila Velha and one female Eumops glaucinus from Vitória (both in bone marrow samples), and one male A. lituratus from Vitória and one male Molossus rufus from Guarapari (both in the spleen samples). To our best knowledge, this is the first report of the detection of Leishmania in bats from Espírito Santo as well as of Leishmania DNA in the bone marrow of bats.

The performance of serological tests for Leishmania infantum infection screening in dogs depends on the prevalence of the disease

Dogs are considered the main reservoir of Leishmania infantum. This protozoan causes visceral leishmaniasis (VL), an uncontrolled urban zoonosis in Brazil. Serological tests and polymerase chain reaction (PCR) on peripheral blood were performed to identify infected dogs in scenarios of higher and lower prevalence of the disease (Teresina and Vitória). One-hundred infected and 57 non-infected animals from Teresina and 100 non-infected animals from Vitória were studied. Animal selection was not dependent on previous serology. The sensitivity (Teresina) and specificity (Teresina and Vitória) were as follows: indirect antibody fluorescence (IFAT) cut-off of 1:40 (IFAT 1:40): 96%, 18%, and 76%; IFAT 1:80: 90%, 33%, and 93%; direct agglutination test (DAT): 96%, 33%, and 98%; fast agglutination screening test (FAST): 93%, 68%, and 100%; immunochromatographic assay with a recombinant rK39 antigen (rK39): 88%, 74%, and 98%; enzyme linked immunosorbent assay (ELISA): 91%, 79%, and 98%; rapid dual-path platform test (TR DPP^®): 98%, 60%, and 98%; and blood PCR: 29%, 93%, and 97%, respectively. In the high transmission area, none of the tests adequately discriminated L. infantum-infected from non-infected dogs. However, in the high transmission city, the area under the receiver operating characteristic (ROC) curve of FAST, DAT, ICrK39, ELISA and TR DPP^® was high.

Occurrence of Leishmania infantum and associated histological alterations in the genital tract and mammary glands of naturally infected dogs

The objectives of this study were to evaluate the occurrence of Leishmania infantum in the male and female genital tract and female mammary glands of dogs and the parasite burden and to identify histological alterations associated with this protozoan. Twenty male and 20 female Leishmania-seropositive dogs with isolation of L. infantum were examined. Tissue samples of the prepuce, glans, epididymis, testes, prostate, vulva, vagina, uterus, uterine tubes, and mammary glands were analyzed by immunohistochemistry and histopathology. For parasitological culture and in situ hybridization, samples were collected from the testis, epididymis, and uterus. Additionally, seminal fluid was aspirated from the epididymis for parasitological culture. In the genital tract, 34 (85 %) dogs, including 18 males and 16 females, were positive for Leishmania. Of these, 27 (79 %) animals were symptomatic. Leishmania was detected in the mammary glands of 13 (65 %) females. L. infantum was isolated for the first time from the seminal fluid and uterus of naturally infected dogs. The parasite burden and intensity of the inflammatory reaction were greater in the prepuce and glans of males and in the vulva and mammary glands of females. In addition to inflammation, testicular degeneration, atrophy, absence of spermatogenesis, and necrosis were observed. Detection of amastigote forms in the mammary gland lumen indicates possible elimination of this parasite in milk. The frequent parasitism observed in the genital tract of infected males and females and the viability of L. infantum in seminal fluid and uterus suggest the possibility of bidirectional venereal and vertical transmission.

Sensitivity and specificity of parallel or serial serological testing for detection of canine Leishmania infection

In Brazil, human and canine visceral leishmaniasis (CVL) caused by Leishmania infantum has undergone urbanisation since 1980, constituting a public health problem, and serological tests are tools of choice for identifying infected dogs. Until recently, the Brazilian zoonoses control program recommended enzyme-linked immunosorbent assays (ELISA) and indirect immunofluorescence assays (IFA) as the screening and confirmatory methods, respectively, for the detection of canine infection. The purpose of this study was to estimate the accuracy of ELISA and IFA in parallel or serial combinations. The reference standard comprised the results of direct visualisation of parasites in histological sections, immunohistochemical test, or isolation of the parasite in culture. Samples from 98 cases and 1,327 noncases were included. Individually, both tests presented sensitivity of 91.8% and 90.8%, and specificity of 83.4 and 53.4%, for the ELISA and IFA, respectively. When tests were used in parallel combination, sensitivity attained 99.2%, while specificity dropped to 44.8%. When used in serial combination (ELISA followed by IFA), decreased sensitivity (83.3%) and increased specificity (92.5%) were observed. Serial testing approach improved specificity with moderate loss in sensitivity. This strategy could partially fulfill the needs of public health and dog owners for a more accurate diagnosis of CVL.

Phlebotomine fauna, natural infection rate and feeding habits of Lutzomyia cruzi in Jaciara, state of Mato Grosso, Brazil

Visceral leishmaniasis (VL) in Brazil is transmitted by the phlebotomine Lutzomyia longipalpis and in some midwestern regions by Lutzomyia cruzi. Studies of the phlebotomine fauna, feeding habits and natural infection rate by Leishmania contribute to increased understanding of the epidemiological chain of leishmaniases and their vectorial capacity. Collections were performed in Jaciara, state of Mato Grosso from 2010-2013, during which time 2,011 phlebotomines (23 species) were captured (68.70% Lu. cruzi and 20.52% Lutzomyia whitmani). Lu. cruzi females were identified by observing the shapes of the cibarium (a portion of the mouthpart) and spermatheca, from which samples were obtained for polymerase chain reaction to determine the rates of natural infection. Engorged phlebotomines were assessed to identify the blood-meal host by ELISA. A moderate correlation was discovered between the number of Lu. cruzi and the temperature and the minimum rate of infection was 6.10%. Twenty-two females were reactive to the antisera of bird (28%), dog (3.30%) and skunk (1.60%). We conclude that Lu. cruzi and Lu. whitmani have adapted to the urban environment in this region and that Lu. cruzi is the most likely vector of VL in Jaciara. Moreover, maintenance of Leishmania in the environment is likely aided by the presence of birds and domestic and synanthropic animals.