American cutaneous leishmaniasis in domestic dogs: an example of the use of the polymerase chain reaction for mass screening in epidemiological studies

Development and Assessment of Leishmania major and Leishmania tropica Specific Loop-Mediated Isothermal Amplification Assays for the Diagnosis of Cutaneous Leishmaniasis in Tunisia

Cutaneous leishmaniasis (CL) remains one of the world's most prevalent neglected diseases, particularly in developing countries. Identification of the involved Leishmania species is an important step in the diagnosis and case management process. In this study, we tested simple, rapid, and highly sensitive loop-mediated isothermal amplification (LAMP) assays for Leishmania DNA species-specific detection from cutaneous lesions. Two LAMP assays, targeting cysteine protease B (cpb) gene, were developed to detect and identify Leishmania major and Leishmania tropica species. Loop-mediated isothermal amplification specificity was examined using DNA samples from other Leishmania species and Trypanosoma species. No cross-reactions were detected. The developed LAMP assays exhibited sensitivity with a detection limit of 20 fg and 200 fg for L. major and L. tropica, respectively. Both tests were applied on clinical samples of CL suspected patients living in endemic Tunisian regions and compared with kinetoplast DNA quantitative PCR (qPCR), microscopic, and conventional cpb-based polymerase chain reaction (PCR) assays. Our LAMP tests were able to discriminate between L. major and L. tropica species and showed a sensitivity of 84% and a specificity of 100%. However, when compared with the performance of the diagnostic tests with latent class analysis (LCA), our LAMP assays show a sensitivity of 100%. These assays can be used as a first-line molecular test for early diagnosis and prompt management of CL cases in public health programs.

A review on the occurrence of companion vector-borne diseases in pet animals in Latin America

Companion vector-borne diseases (CVBDs) are an important threat for pet life, but may also have an impact on human health, due to their often zoonotic character. The importance and awareness of CVBDs continuously increased during the last years. However, information on their occurrence is often limited in several parts of the world, which are often especially affected. Latin America (LATAM), a region with large biodiversity, is one of these regions, where information on CVBDs for pet owners, veterinarians, medical doctors and health workers is often obsolete, limited or non-existent. In the present review, a comprehensive literature search for CVBDs in companion animals (dogs and cats) was performed for several countries in Central America (Belize, Caribbean Islands, Costa Rica, Cuba, Dominican Republic, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama, Puerto Rico) as well as in South America (Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, French Guiana, Guyana (British Guyana), Paraguay, Peru, Suriname, Uruguay, Venezuela) regarding the occurrence of the following parasitic and bacterial diseases: babesiosis, heartworm disease, subcutaneous dirofilariosis, hepatozoonosis, leishmaniosis, trypanosomosis, anaplasmosis, bartonellosis, borreliosis, ehrlichiosis, mycoplasmosis and rickettsiosis. An overview on the specific diseases, followed by a short summary on their occurrence per country is given. Additionally, a tabular listing on positive or non-reported occurrence is presented. None of the countries is completely free from CVBDs. The data presented in the review confirm a wide distribution of the CVBDs in focus in LATAM. This wide occurrence and the fact that most of the CVBDs can have a quite severe clinical outcome and their diagnostic as well as therapeutic options in the region are often difficult to access and to afford, demands a strong call for the prevention of pathogen transmission by the use of ectoparasiticidal and anti-feeding products as well as by performing behavioural changes.

Domestic dogs as reservoir hosts for Leishmania donovani in the southernmost Western Ghats in India

The peripheral blood samples from domestic dogs (n=47) and wild rats (n=25) in the Kani Tribe settlements, located southernmost part of the Western Ghats, Thiruvananthapuram district, Kerala, India were examined for Leishmania infection. This area is known for cases of leishmaniasis with cutaneous manifestations and sandfly abundance. The tribes domesticate dogs to protect them from untoward activities of wild animals. Leishmania donovani parasite DNA was detected only from 6.4% (n=3) of the blood samples collected from the domestic dogs by amplification of the diagnostic kinetoplast mini-circle DNA and PCR-RFLP analysis of the UTR region of heat shock protein 70 (hsp70) gene. None of the blood samples collected from rats was positive. Through sequencing, L. donovani infection among dogs was confirmed. The DNA sequences generated for hsp70 were deposited with the GenBank. The GenBank accession numbers of these samples are KR905363, KR905364 and KR905365 for hsp70 genes. The results indicated that the DNA isolates from dog blood samples matched precisely with that of our earlier isolates from skin lesions of Kani tribes and also from P. argentipes vector. Thus, the role of dogs as reservoirs for L. donovani parasite in the Kani tribe settlements is confirmed.

Cutaneous Leishmaniasis in dogs: is high seroprevalence indicative of a reservoir role?

American cutaneous leishmaniasis (ACL) is a complex disease with a rich diversity of animal host species. This diversity imposes a challenge, since understanding ACL transmission requires the adequate identification of reservoir hosts, those species able to be a source of additional infections. In this study we present results from an ACL cross-sectional serological survey of 51 dogs (Canis familiaris), where we used diagnostic tests that measure dog's exposure to Leishmania spp. parasites. We did our research in Panamá, at a village that has undergone significant ecosystem level transformations. We found an ACL seroprevalence of 47% among dogs, and their exposure was positively associated with dog age and abundance of sand fly vectors in the houses of dog owners. Using mathematical models, which were fitted to data on the proportion of positive tests as function of dog age, we estimated a basic reproductive number (R 0 ± s.e.) of 1·22 ± 0·09 that indicates the disease is endemically established in the dogs. Nevertheless, this information by itself is insufficient to incriminate dogs as ACL reservoirs, given the inability to find parasites (or their DNA) in seropositive dogs and previously reported failures to experimentally infect vectors feeding on dogs with ACL parasites.

Comparison of Leishmania OligoC-TesT PCR with conventional and real-time PCR for Diagnosis of canine Leishmania infection

There is a need for standardization and simplification of the existing methods for molecular detection of Leishmania infantum in the canine reservoir host. The commercially available OligoC-TesT kit incorporates standardized PCR reagents with rapid oligochromatographic dipstick detection of PCR products and is highly sensitive for use in humans but not yet independently validated for use in dogs. Here we compare the sensitivity of OligoC-TesT with those of nested kinetoplast DNA (kDNA) PCR, nested internal transcribed spacer 1 (ITS-1) PCR, and a PCR-hybridization protocol, using longitudinal naturally infected canine bone marrow samples whose parasite burdens were measured by real-time quantitative PCR (qPCR). The sensitivity of OligoC-TesT for infected dogs was 70% (95% confidence interval [CI], 63 to 78%), similar to that of kDNA PCR (72%; 95% CI, 65 to 80%; P = 0.69) but significantly greater than those of PCR-hybridization (61%; 95% CI, 53 to 69%; P = 0.007) and ITS-1 nested PCR (54%; 95% CI, 45 to 62%; P < 0.001); real-time qPCR had the highest sensitivity (91%; 95% CI, 85 to 95%; P < 0.001). OligoC-TesT sensitivity was greater for polysymptomatic and oligosymptomatic dogs than for asymptomatic dogs (93%, 74%, and 61%, respectively; P = 0.005), a trend also observed for the other qualitative PCR methods tested (P <or= 0.05). Test positivity increased with increasing parasite burdens, as measured by real-time qPCR: OligoC-TesT and kDNA PCR detected 100% and 99% of positive samples when parasite burdens exceeded 74 and 49 parasites/ml, respectively. OligoC-TesT has high sensitivity for detection of canine Leishmania infections; its ease of operation and ease of interpretation are further advantages for veterinary diagnostic laboratories and for large-scale survey work in developing countries.

A serological and molecular investigation of American cutaneous leishmaniasis in dogs, three years after an outbreak in the Northwest of Paraná State, Brazil

Classic and molecular (polymerase chain reaction--PCR) techniques were used to diagnose American cutaneous leishmaniasis in 149 dogs from an area in the northwest of Paraná State, Brazil, where an American cutaneous leishmaniasis outbreak occurred in 2002. The results were compared to a set of previously obtained results. Twenty-five dogs had positive indirect immunofluorescence (IIF) (titers > or = 40), including two animals with suggestive lesions. The percentage of dogs with positive IIF was similar to that found in a previous study. The cultures of the lesion, blood and bone marrow were negative for Leishmania. A direct search for the parasite in the lesions proved negative, although PCR tests were positive. The PCR did not detect the DNA of Leishmania (Viannia) in the blood, even for those that had positive PCR in a previous study. The follow up of the 27 dogs showed that the majority of them had maintained the same levels of antibodies that had been detected previously. There was a reduction in the number of dogs with lesions, probably due to the transmission control measures that were adopted after the outbreak.

DNA sequencing confirms the involvement of Leishmania (L.) amazonensis in American tegumentary leishmaniasis in the state of São Paulo, Brazil

INTRODUCTION

American tegumentary leishmaniasis (ATL) represents one of the most important public health issues in the world. An increased number of autochthonous cases of ATL in the Northeastern region of São Paulo State has been documented in the last few years, leading to a desire to determine the Leishmania species implicated.

METHODS

PCR followed by DNA sequencing was carried out to identify a 120bp fragment from the universal kDNA minicircle of the genus Leishmania in 61 skin or mucosal biopsies from patients with ATL.

RESULTS

DNA sequencing permitted the identification of a particular 15bp fragment (5' GTC TTT GGG GCA AGT... 3') in all samples. Analysis by the neighbor-joining method showed the occurrence of two distinct groups related to the genus Viannia (V) and Leishmania (L), each with two subgroups. Autochthonous cases with identity to a special Leishmania sequence not referenced in Genbank predominated in subgroup V.1, suggesting the possible existence of a subtype or mutation of Leishmania Viannia in this region. In the subgroup L.2, which showed identity with a known sequence of L. (L.) amazonensis, there was a balanced distribution of autochthonous and non-autochthonous cases, including the mucosal and mucocutaneous forms in four patients. The last observation may direct us to new concepts, since the mucosal compromising has commonly been attributed to L. (V.) braziliensis, even though L. (L.) amazonensis is more frequent in the Amazonian region.

CONCLUSIONS

These results confirm the pattern of distribution and possible mutations of these species, as well as the change in the clinical form presentation of ATL in the São Paulo State.

PCR in the investigation of canine American tegumentary leishmaniasis in northwestern Paraná State, Brazil

American tegumentary leishmaniasis (ATL) was studied in 143 dogs in a rural area in the county of Mariluz, northwestern Paraná State, Brazil, using direct parasite search, indirect immunofluorescence (IIF), and polymerase chain reaction (PCR). Thirty-nine dogs (27.3%) presented lesions suggestive of the disease, 5 (12.8%) of which were positive in direct parasite search and PCR (lesion), and of these 5, 4 were also positive by IIF. Of the 34 dogs with negative direct parasite search, 12 (35.3%) had PCR- positive lesions, and of these, 5 were also IIF-positive. One hundred and four dogs had no lesions, but 17/101 (16.8%) were IIF-positive. PCR in blood was positive in 10/38 (26.3%) of the dogs with lesions and in 16/104 (15.4%) of dogs without lesions. The association between PCR (lesion or blood), direct parasite search, and IIF detected 24/39 (61.5%) positive results among symptomatic dogs and 31/104 (29.8%) among asymptomatic animals. PCR was useful for diagnosing ATL, but there was no correlation between lesions, serology, and plasma PCR. Furthermore, detection of parasite DNA in the blood may indicate hematogenous parasite dissemination.