Quantification of Leishmania infantum DNA in females, eggs and larvae of Rhipicephalus sanguineus

Q3 lab-on-chip real-time PCR for the diagnosis of Leishmania infantum infection in dogs

Leishmaniasis is a vector-borne disease caused by many Leishmania spp. which infect humans and other mammalian hosts. Leishmania infantum is the main agent of canine leishmaniasis (CanL) whose diagnosis is usually confirmed by serological and molecular tests. This study aimed to evaluate the clinical and analytical sensitivities of a lab-on-chip (LOC) real-time PCR applied on the portable Q3-Plus V2 platform (Q3 qPCR) in the detection of L. infantum. The Q3 qPCR performance was assessed by comparing the quantification cycle (Cq) values with those obtained using the qPCR run on a CFX96 Real-Time System (CFX96 qPCR). A total of 173 DNA samples (extracted from bone marrow, lymph node, blood, buffy coat, conjunctival swab, and skin) as well as 93 non-extracted samples (NES) (bone marrow, lymph node, blood, and buffy coat) collected from dogs were tested with both systems. Serial dilutions of each representative DNA and NES sample were used to assess the analytical sensitivity of the Q3 qPCR system. Overlapping Cq values were obtained with the Q3 qPCR and CFX96 qPCR, both using DNA extracted from L. infantum promastigotes (limit of detection, <1 promastigote per milliliter) and from biological samples as well as with NES. However, the Q3 qPCR system showed a higher sensitivity in detecting L. infantum in NES as compared with the CFX96 qPCR. Our data indicate that the Q3 qPCR system could be a reliable tool for detecting L. infantum DNA in biological samples, bypassing the DNA extraction step, which represents an advance in the point-of-care diagnostic of CanL.

Ein Update zur Leishmaniose des Hundes: Diagnostik, Therapie und Monitoring

Aufgrund von steigenden Importzahlen von Hunden aus dem Ausland, zunehmendem Reiseverkehr sowie den Veränderungen klimatischer Bedingungen in Europa gewinnen Infektionen mit Leishmania (L.) infantum bei Hunden in Deutschland zunehmend an Bedeutung. Daher sollten auch Hunde aus dem Ausland, die keine klinischen Symptome zeigen, direkt nach Import sowie erneut 6 Monate später auf vektorübertragene Infektionserreger getestet werden. Bei Hunden mit klinischer Symptomatik, die hinweisend auf eine Leishmaniose sind, werden direkte und indirekte Nachweisverfahren sowie eine hämatologische und biochemische Untersuchung unter Einbezug von Serumeiweißelektrophorese sowie Bestimmung des C-reaktiven Proteins empfohlen. Als Leitfaden für die Therapie sowie das Monitoring stehen die LeishVet-Guidelines zur Verfügung. Es stehen leishmanizide und leishmaniostatische Wirkstoffe zur Verfügung, die in first-line, second-line und third-line unterschieden werden. Zur Anpassung der Allopurinol-Dosierung wird der Stufenplan empfohlen. Aufgrund der Veränderung der klimatischen Bedingungen kommt es zu einer Ausbreitung der Habitate von Sandmücken, die als Vektoren der Leishmaniose bekannt sind. Als weitere Infektionsquellen sind Deckakte, transplazentare Infektionen, Bisswunden und Bluttransfusionen beschrieben. Leishmania infantum hat zoonotisches Potential und ist daher auch in Hinblick auf den „One-Health“-Gedanken bedeutend.

Detection of Leishmania sp. kDNA in questing Ixodes ricinus (Acari, Ixodidae) from the Emilia-Romagna Region in northeastern Italy

To date, sand flies (Phlebotominae) are the only recognized biological vectors of Leishmania infantum, the causative agent of human visceral leishmaniasis, which is endemic in the Mediterranean basin and also widespread in Central and South America, the Middle East, and Central Asia. Dogs are the main domestic reservoir of zoonotic visceral leishmaniasis, and the role of secondary vectors such as ticks and fleas and particularly Rhipicephalus sanguineus (the brown dog tick) in transmitting L. infantum has been investigated. In the present paper, the presence of Leishmania DNA was investigated in questing Ixodes ricinus ticks collected from 4 rural areas included in three parks of the Emilia-Romagna Region (north-eastern Italy), where active foci of human visceral leishmaniasis have been identified. The analyses were performed on 236 DNA extracts from 7 females, 6 males, 72 nymph pools, and 151 larvae pools. Four samples (1.7%) (i.e., one larva pool, 2 nymph pools, and one adult male) tested positive for Leishmania kDNA. To the best of our knowledge, this is the first report of the presence of Leishmania kDNA in questing I. ricinus ticks collected from a rural environment. This finding in unfed larvae, nymphs, and adult male ticks supports the hypothesis that L. infantum can have both transstadial and transovarial passage in I. ricinus ticks. The potential role of I. ricinus ticks in the sylvatic cycle of leishmaniasis should be further investigated.

Molecular identification and genetic analysis of Rhipicephalus sanguineus sensu lato of dogs in Nigeria, West Africa

The brown dog tick, Rhipicephalus sanguineus sensu lato, is a ubiquitous and taxonomically controversial pest of dogs with immense veterinary and public health significance. Genetic analyses of specimens from various geographical origins reveal intraspecific diversity within the taxon. Little information is available on the genetic characteristics of R. sanguineus s.l. in Nigeria, West Africa. In this study, 460 bp of the mitochondrial 16S rDNA gene of R. sanguineus s.l. collected from dogs in different ecological zones of Nigeria was amplified, sequenced and characterized. Phylogenetic and pairwise analyses were used to compare the sequences generated in this study to each other and to sequences in GenBank. The sequences in this study were highly similar (>98%) to each other and clustered with sequences of the R. sanguineus s.l. tropical lineage in GenBank. None of the sequences in this study clustered with the 'southeastern Europe' or temperate lineage. The mean intraspecific divergence among R. sanguineus s.l. in this study was 1.7% (range: 0-8.0%). Furthermore, the sequences in this study showed mean divergence of 1.5% (0-10%), 5.0% (3.8-13.9%) and 9.7% (6.9-19.8%) from sequences of the tropical, southeastern Europe and temperate lineages, respectively. Interestingly, sequences in this study showed a mean divergence of 9.3% (1.0-17.8%) from the Rhipicephalus sp. morphotype 4 (GenBank acc. nr. KC243850) earlier identified from cattle in Nigeria, suggesting diversity in this taxon in Nigeria. Further studies are needed to elucidate the veterinary and public health significance of R. sanguineus s.l. in Nigeria taking into cognizance the existence of intraspecific variation in vector competence.

Canine visceral leishmaniasis and Rhipicephalus sanguineus: evaluation and comparison of classical techniques

The aim of this study was evaluating the association and correlation between the diagnostics tests used for Leishmania spp. detection in dogs and ticks. We evaluated 99 dogs and 990 Rhipicephalus sanguineus. In dogs, we used bone marrow aspirates and lymph node fine-needle aspiration biopsy (FNAB) for direct parasitological examinations and real time-polymerase chain reaction (RT-PCR) and collected blood samples for enzyme-linked immunosorbent assays (ELISA). In ticks, two laboratory techniques [immunohistochemistry to lipophosphoglycan (IHC) and RT-PCR] were performed in the intestine, ovaries and salivary glands. With respect to the measurement of diagnostic performance in dogs, lymph node RT-PCR proved to be the best test followed by ELISA and bone marrow RT-PCR. In ticks, intestine IHC were considered as a gold standard for diagnosis of leishmaniasis with intestinal RT-PCR being the best diagnostic test. To arrive at the correlation between laboratory techniques for dogs and their ticks, we evaluated the diagnostic test used for dogs with tests performed in R. sanguineus, which used lymph node FNAB as the gold standard. The intestine IHC technique showed strongest association. We demonstrated that the best tissue for Leishmania spp. detection in dogs was the lymph node and the intestine in case of ticks. As for laboratory techniques, the isolated analysis of each species presented a strong agreement between immunohistochemistry and RT-PCR when compared to its gold standard. In addition, we concluded that the immunohistochemistry of ticks' intestines was a better technique for diagnosing Leishmania spp. in R. sanguineus, thereby showing almost perfect correlation with the lymph node FNAB.

Leishmania infantum in wild animals in endemic areas of southern Italy

Leishmania infantum infection in wildlife is increasingly reported in Europe, but scant data are available in Italy so far. This study aimed to investigate the circulation of L. infantum among sylvatic hosts in Sicily (southern Italy), a highly endemic area for canine leishmaniosis, through serological and molecular tools. Target tissues (skin, spleen, lymph nodes) collected from 71 European rabbits, 2 European hares, 7 red foxes, 11 European wildcats and 1 pine marten, were qPCR analysed for the detection of L. infantum DNA. Additionally, 40 rabbits, older than one year, were serologically screened for specific anti-Leishmania antibodies. Leishmania infantum was molecularly diagnosed in 5.4% (n = 5) of the examined animals (3/71 European rabbits, 2/7 red foxes). In many of the qPCR positive animals (4/5), the parasite DNA was more prevalent in visceral than cutaneous tissues. None of the positive animal showed signs of disease and/or macroscopic alterations of organs; low parasitic burden in all positive tissue samples was also recorded. Only one rabbit serum (i.e., 2.5%) tested positive for anti-Leishmania antibodies. The seropositive rabbit was in good health status and no amastigotes were observed in lymph-node aspirate and blood smears. This study provides first evidence of L. infantum infection in wild animals from Sicily (southern Italy). Despite the low prevalence of infection here reported, the circulation of the Leishmania in wild reservoirs in Sicily remains worthy of future investigations for a better understanding of their role in the epidemiology of the disease as well as to fine-tune control strategies in the area.

Risk of establishment of canine leishmaniasis infection through the import of dogs into South Africa

Canine leishmaniasis is a vector-borne disease caused by protozoa of the genus Leishmania that affect dogs, humans and wildlife. Sandflies of the genera Phlebotomus and Lutzomyia are the primary vectors. Canine leishmaniasis is an exotic and controlled disease in South Africa. The main purpose of our risk assessment study was to evaluate the likelihood that this exotic disease could enter and be established in South Africa through importation of live dogs. Risk analysis to the spread of the disease follows the World Organization for Animal Health (OIE) formal method of quantitative risk assessment documented as a step-by-step process. We have identified and discussed 11 possible risk factors involved in three steps for final assessment. The annual average number of diagnostic tests performed on imported dogs from 44 countries for 2011-2015 was 1158. Leishmania is reported to occur in 21/44 (47.7%) exporting countries. A total of 71.1% of Leishmania positive dogs were imported from these endemic countries. The yearly percentage of Leishmania positive dogs ranged from 0.2% to 2%. Three confirmed clinical and fatal cases of leishmaniasis in dogs of unidentified origin have been reported by our laboratory and the state veterinarians. The disease has been reported in neighbouring countries as well as the putative sandfly vectors. This study concluded that the risk for the introduction and degree of uncertainty of Leishmania in imported dogs in South Africa are moderate. Risk mitigation and recommendations such as investigations into possible occurrence of autochthonous leishmaniasis in the country, surveillance in its wildlife reservoirs and systematic surveillance of sandfly populations are discussed.

Leishmaniosis in a dog with no travel history outside of the UK

A 3-year-old male neutered Shih Tzu cross was presented for investigation of a three-week history of weight loss, seborrhoea, vomiting and diarrhoea. Initial clinicopathological findings included pancytopenia, mild hypercalcaemia and marked hyperglobulinaemia. Subsequent bone marrow and skin biopsies revealed the presence of Leishmania amastigotes. Quantitative serology was positive for Leishmania species and PCR on the bone marrow sample confirmed a Leishmania infantum infection. The patient had been in the owner's possession since a puppy, had no travel history outside of the UK and had never received a blood transfusion or been used for breeding. However, another dog in the household that had been imported from Spain had been euthanased six months previously due to severe leishmaniosis. To the authors' knowledge, this is the first reported case of canine leishmaniosis in the UK without a history of travel to an endemic area, and most likely represents a case of dog-to-dog transmission.

Denaturing Gradient Gel Electrophoresis Analysis of Bacteria in Italian Ticks and First Detection of Streptococcus equi in Rhipicephalus bursa from the Lazio Region

Tick-borne diseases are an increasing problem for the community. Ticks harbor a complex microbial population acquired while feeding on a variety of animals. Profiling the bacterial population by 16S rDNA amplification and denaturing gradient gel electrophoresis enables detection of the broad spectrum of bacteria that settles in the ticks. This study identified known and unknown tick-infecting bacteria in samples from Italy. Seven adult ticks from different hosts and origins were analyzed: two Rhipicephalus sanguineus ticks from dogs (Lombardia), two Rhipicephalus bursa ticks from bovines (Lazio), and three Ixodes ricinus ticks from humans (Marche). The major result was the first report of the zoonotic agent Streptococcus equi in ticks. S. equi is a species complex of highly contagious pathogens. Subsequent to S. equi detection in a R. bursa tick removed from a bovine of Lazio in 2012, we studied 95 R. bursa samples collected from 3 bovines, 3 ponies, and 1 sheep grazing in the same area in 2012 and from 6 ponies grazing there in 2017. The results of a specific PCR assay indicated a not sporadic occurrence of S. equi in ticks. This finding provides a basis for assessing the potential of ticks to harbor and disperse S. equi.

Real-time PCR applications for diagnosis of leishmaniasis

Leishmaniasis is a vector-borne disease caused by many Leishmania species, which can infect both humans and other mammals. Leishmaniasis is a complex disease, with heterogeneous clinical manifestations ranging from asymptomatic infections to lesions at cutaneous sites (cutaneous leishmaniasis), mucosal sites (mucocutaneous leishmaniasis) or in visceral organs (visceral leishmaniasis), depending on the species and host characteristics. Often, symptoms are inconclusive and leishmaniasis can be confused with other co-endemic diseases. Moreover, co-infections (mainly with HIV in humans) can produce atypical clinical presentations. A correct diagnosis is crucial to apply the appropriate treatment and the use of molecular techniques in diagnosis of leishmaniasis has become increasingly relevant due to their remarkable sensitivity, specificity and possible application to a variety of clinical samples. Among them, real-time PCR (qPCR)-based approaches have become increasingly popular in the last years not only for detection and quantification of Leishmania species but also for species identification. However, despite qPCR-based methods having proven to be very effective in the diagnosis of leishmaniasis, a standardized method does not exist. This review summarizes the qPCR-based methods in the diagnosis of leishmaniasis focusing on the recent developments and applications in this field.

Detection of Leishmania infantum DNA in phlebotomine sand flies from an area where canine leishmaniosis is endemic in southern Italy

Phlebotomine sand flies (Diptera, Psychodidae) are vectors of Leishmania spp., among which Leishmania infantum is recognized as the main agent of human and canine leishmaniosis (CanL) in the Mediterranean area. In this study, females of Phlebotomus spp. (P. perniciosus, P. neglectus and P. papatasi) and Sergentomyia minuta were collected in a dog shelter of southern Italy, where CanL is endemic, and examined for Leishmania DNA. In total, 32 out of 56 of Phlebotomus spp. insects (57.1%) were found positive for L. infantum DNA by quantitative PCR (qPCR), with a mean parasite load of 1.9 × 10³ promastigotes/ml among 23 positive P. perniciosus and 2.1 × 10³ promastigotes/ml among five positive P. neglectus. Four P. papatasi, a species known to be refractory to L. infantum development, were also found positive. Among 216 S. minuta specimens examined, 25 (11.6%) scored positive for Leishmania tarentolae by conventional nested PCR; two (16.7%) of them were also positive for lizard blood, which is in agreement with the feeding preference of this phlebotomine species. Nine S. minuta (4.2%) were positive for L. infantum by qPCR, with a mean parasite load of 1.62 × 10² promastigotes/ml. The detection of L. infantum DNA in S. minuta may suggest that this species could acquire the protozoan, occasionally feeding on infected dogs. Further investigations need to clarify the potential role that S. minuta may have in the transmission of L. infantum to receptive mammal hosts.

Natural transovarial and transstadial transmission of Leishmania infantum by naïve Rhipicephalus sanguineus ticks blood feeding on an endemically infected dog in Shiraz, south of Iran

BACKGROUND

The visceral leishmaniasis parasite, Leishmania infantum, is naturally transmitted through the bites of phlebotomine sand flies. Alternative routes of transmission are questioned. The main aim is to verify the passage of L. infantum kDNA in ticks, Rhipicephalus sanguineus, blood feeding on a parasitemic dog in Shiraz, south of Iran.

METHODS

A total of 180 Leishmania-free ticks collected from fields and bred on lab rodents, were divided into eight groups and allowed to feed on a dog (Canis familiaris) for fixed periods of time. These and all third generation stages of ticks were checked for L. infantum kDNA using conventional PCR protocol.

RESULTS

The infection rate was significantly higher in female than male ticks (p=0.043). The rates were higher among nymphs (25/60; 42%) than adult ticks (37/120; 30.8%). The kDNA of L. infantum was not detected in ticks 24 h post-feeding. It was, however, positive among the second to fourth groups of nymphs (4/10; 40%, 10/20; 50% and 11/20; 55%) and adult (12/30; 40%, 14/30; 46.6% and 11/30; 36.6%) ticks. Eggs and unfed larvae recovered from the third and fourth adult groups (2 weeks, 4 weeks) were 100% PCR-positive. The data revealed the passage of L. infantum kDNA in nymphs and adults of brown dog tick following fixed time intervals post blood feeding on an infected dog.

CONCLUSIONS

The natural transovarial and transstadial passage of kDNA through ticks was shown by PCR.

Prevention of feline leishmaniosis with an imidacloprid 10%/flumethrin 4.5% polymer matrix collar

Background

Leishmaniosis caused by Leishmania infantum is one of the most important vector-borne diseases affecting animals and humans worldwide. Dogs are considered main reservoirs of the zoonotic forms, though in the last years the role of cats as reservoirs has been increasingly investigated. Feline leishmaniosis (FeL) occurs in endemic areas and no specific preventive measures have been investigated so far. In this study the efficacy of a 10% imidacloprid/4.5% flumethrin polymer matrix collar, licensed for tick and flea prevention, has been assessed against FeL in a longitudinal study on 204 privately owned cats from the Aeolian islands (Sicily), an area highly endemic for the disease. From March to May 2015 [Study Day 0 (SD 0)], cats negative for FeL were collared (G1, n = 104) or left untreated (G2, n = 100). Diagnosis consisted of serology and qPCR on blood and conjunctival swabs, which were collected at baseline (SD 0) and at the end of the study (SD 360). Interim clinical examinations were performed on SD 210 (when collars were replaced in G1) and SD 270.

Results

Of the 159 cats which completed the study, 5 in G1 and 20 in G2 were positive for L. infantum infection, in at least one of the diagnostic tests leading to a yearly crude incidence of 6.3% and 25.0% in G1 and G2, respectively (P = 0.0026). This translates into an efficacy of the collar of 75.0% in preventing feline Leishmania infection. The collar was generally well tolerated with no systemic adverse reactions and few local skin reactions were observed in the application area in four out of 104 treated cats (3.8%).

Conclusions

The 10% imidacloprid/4.5% flumethrin collar significantly reduced the risk of L. infantum infection in cats. To our knowledge, this is the first study in which a preventative strategy against feline Leishmania infection is assessed under natural conditions. These findings close a gap in veterinary medicine, in that they confirm this collar as a tool in reducing the risk of Leishmania infection in cats. Such a preventative tool could contribute to the reduction of the risk of the disease in animal and in human populations when included in integrated leishmaniosis control programmes.

Mitochondrial DNA analysis of Rhipicephalus sanguineus s.l. from the western Iberian peninsula

Rhipicephalus sanguineus Latreille (1806) (Ixodida: Ixodidae) is considered to be the most widely distributed tick and to have a vast range of habitats and hosts, including livestock, pets and wildlife. In addition to morphological differences, recent investigations using approaches based on molecular genetic markers have revealed the existence of different R. sanguineus lineages in different geographic regions. In this study, 475 ticks collected from dogs in the western Iberian peninsula were studied both morphologically and genetically, using 12S and 16S rDNA and COI gene markers in order to clarify the controversy over the systematic status of R. sanguineus sensu lato in Western Europe, and to compare the present data with those sourced from studies conducted in other regions of the world. Despite the high morphometric variability, particularly on spiracles in both genders and in female genitalia, data obtained with different genetic molecular markers show very low variability, suggesting the existence of a unique species. In addition, the phylogenetic analysis showed genetic uniformity, supporting the existence of a well-defined clade consisting of R. sanguineus s.l. specimens from Western Europe that are distinct from R. sanguineus s.l. from Africa. Furthermore, these data corroborate the existence of a polymorphic species in Western Europe, which requires to be consensually redescribed in view of its medical and veterinary importance in pathogen transmission.

Exposure to vector-borne pathogens in privately owned dogs living in different socioeconomic settings in Brazil

This survey was conducted in four Brazilian cities, from three federative units (Pernambuco, Minas Gerais, and Federal District), representing different socioeconomic settings, to determine the presence of antibodies to or antigens and DNA of selected pathogens in privately owned dogs. From January to April 2015, blood and serum samples were collected and assayed using different tests. In particular, antibodies to Anaplasma spp., Borrelia burgdorferi sensu lato, and Ehrlichia spp., and antigens of Dirofilaria immitis were detected using a rapid enzyme-linked immunosorbent assay, whereas antibodies to Babesia spp. were detected by an immunofluorescence antibody assay. Moreover, the presence of Leishmania DNA in blood samples was assessed by real-time polymerase chain reaction. Overall, 208 (69.3%) out of 300 dogs were positive for at least one tested pathogen (intended here as antibodies, antigen or DNA, as abovementioned), with 139 (66.8%) of them being positive to two or more pathogens. No dog presented antibodies to B. burgdorferi s.l., and D. immitis antigens were detected exclusively in dogs from Pernambuco. Among positive dogs, the most common clinical signs were lymphadenomegaly (45.2%), onychogryphosis (41.3%), dermatitis (34.1%), pale mucous membranes (19.7%), weight loss (14.9%), fever (12.5%), alopecia (11.1%), and lethargy (4.8%). Tick and flea infestations were recorded in 41.7% and 29.3% of the dogs, respectively, with 49 (16.3%) dogs being co-infested by both ticks and fleas. Most of the tick- and flea-infested dogs presented high level of infestation (>10 ticks and >20 fleas). The level of tick infestation varied significantly among federative units, being highest in Minas Gerais (68.0%), followed by Pernambuco (36.0%) and Federal District (21.0%). On the other hand, the level of flea infestation was higher in Pernambuco (50.0%), followed by Minas Gerais (29.0%) and Federal District (9.0%). The number of dog owners reporting the use of ectoparasiticides (on dogs and/or in the environment) varied significantly, ranging from 6.0% in Pernambuco to 60.0% in Federal District. This study reveals disparate results in terms of dog exposure to fleas and ticks in the studied communities, which may be related to factors such as the owners' capability/willingness to afford the use of ectoparasiticides on their dogs and the dog's level of restriction. Further research is needed to establish the relationship between dog owners' socioeconomic situation and the level of exposure to ectoparasites and their transmitted pathogens.

Detection of Leishmania (V) guyanensis in Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) collected from Pecari tajacu

INTRODUCTION

Previous studies identified the presence of Leishmania infantum in Rhipicephalus sanguineus and indicated the possibility that it could transmit leishmaniasis to a variety of hosts.

OBJECTIVE

To identify parasites of Leishmania (Viannia) spp. in ticks collected from wild animals in an endemic area for leishmaniasis.

MATERIALS AND METHODS

We performed 81 individual DNA extractions from ticks collected from three Tapirus terrestris and three Pecari tajacu in Madre de Dios, Perú. Ticks were taxonomically identified and they were subsequently prepared to identify Leishmania (Viannia) spp. kDNA by PCR and the species of Leishmania by HRM-PCR.

RESULTS

Leishmania (Viannia) kDNA was detected in three wild ticks of the species R. microplus, collected from a collard peccary (P. tajacu) hunted in the forests of Madre de Dios. The HRM-PCR showed that one of the positive samples had a kDNA curve compatible with L. (V) guyanensis.

CONCLUSION

The results showed the presence of L. (V) guyanensis DNA in R. microplus possibly acquired after biting a collarde peccary. Therefore, it is important to design future studies to clarify R. microplus involvement in the transmission of leishmaniasis.

Leishmania-FAST15: A rapid, sensitive and low-cost real-time PCR assay for the detection of Leishmania infantum and Leishmania braziliensis kinetoplast DNA in canine blood samples

We describe an improved real-time PCR assay (designated as "Leishmania-FAST15") for the detection and quantification of Leishmania infantum and Leishmania braziliensis kinetoplast DNA minicircles in canine blood samples. The analytical sensitivity of this technique is 0.1 fg of DNA, which is equivalent to 0.002 parasite per reaction. This assay uses a small reaction volume (15 μl) and is rapid to perform, with the results being available in less than 34 min. This improved assay might also be suitable for detecting and quantifying L. infantum and L. braziliensis DNA in other tissues, such as bone marrow and lymph nodes.

Detection and quantification of Leishmania infantum in naturally and experimentally infected animal samples

Leishmania infantum is one of the causative agents of visceral leishmaniasis (VL). VL is the most severe form of leishmaniasis and can be fatal if it is not properly treated. Although several PCR works are intended to detect L. infantum, in silico analysis of available primers and/or primer-probes reveals potential cross species amplification. Here, a TaqMan-based quantitative real time PCR (qPCR) assay was developed for specific detection and quantitation of L. infantum in tissue samples from experimentally or naturally infected animals, mice or dogs, respectively. For this assay, primers and probes were designed for the kinetoplast minicircle DNA of L. infantum. The qPCR assay achieved a detection limit of 0.01pg of parasite DNA, and allowed specific amplification of L. infantum in both asymptomatic and symptomatic naturally infected dogs with inter-assay variation coefficients between 0.05-0.11. There was no cross amplification with dog DNA or with L. braziliensis, L. donovani, L. major, L. tropica or Trypanosoma cruzi. In addition, our assay detected a significantly higher parasite load in symptomatic than in the asymptomatic animals (p<0.0001). We believe this approach will be a valuable tool for the specific detection of L. infantum in regions of sympatric transmission of VL-causing parasites.

Vertical transmission of Anaplasma platys and Leishmania infantum in dogs during the first half of gestation

Background

Leishmania infantum is a canine zoonotic vector-borne protozoan pathogen transmitted by phlebotomine sand flies, whereas Anaplasma platys is a bacterium most likely transmitted by ticks. While vertical transmission of L. infantum from pregnant bitches to their offspring has been documented, thus far no studies have explored the possibility of vertical transmission of A. platys in dogs. This study investigated the occurrence of vertical transmission of L. infantum and A. platys in sheltered dogs during the first half of gestation, in an area of southern Italy characterised by a high incidence of infection by both pathogens.

Methods

The study population included 20 bitches (n = 10 pregnant, at 25–35 days of pregnancy; n = 10 non-pregnant), all subjected to ovariohysterectomy, which were examined for the presence of L. infantum and A. platys via cytological screening of bone marrow and whole blood samples. Infection by L. infantum and A. platys was also tested by immunofluorescence antibody test (IFAT) and quantitative real-time PCR (qPCR) targeting both pathogens. Selected tissue samples (n = 210) collected during surgical procedures from bitches and foetuses (n = 20) were assessed for the presence of L. infantum and A. platys by qPCR targeting a fragment of the kinetoplast minicircle DNA (kDNA) and the 16S rRNA gene, respectively.

Results

Leishmania infantum DNA was not amplified from either uteri or ovaries from pregnant bitches or foetal tissue samples, whereas a subset of ovarian (n = 2) and uterine (n = 4) tissue samples from non-pregnant bitches were infected, with parasite loads of up to 3.09 × 10 and 7.51 parasite/PCR reaction, respectively. Conversely, uterine (n = 10) and ovarian (n = 8) tissues from both pregnant and non-pregnant bitches, together with a subset (n = 5) of foetal tissue samples were qPCR positive for A. platys. Leishmania infantum and A. platys nucleic acids were amplified from two uteri from non-pregnant bitches, with parasite loads of up to 2.32 × 10^-3 and 2.05 parasite/per PCR reaction, respectively.

Conclusions

Results from this study suggest that, in contrast to L. infantum, A. platys can be transmitted from pregnant dogs to their offspring during the first half of gestation. This hypothesis remains to be verified, for instance via direct observation of parasites in postpartum foetal tissues.

Successful isolation of Leishmania infantum from Rhipicephalus sanguineus sensu lato (Acari: Ixodidae) collected from naturally infected dogs

BACKGROUND

The main transmission route of Leishmania infantum is through the bites of sand flies. However, alternative mechanisms are being investigated, such as through the bites of ticks, which could have epidemiological relevance. The objective of this work was to verify the presence of Leishmania spp. in Rhipicephalus sanguineus sensu lato collected from naturally infected dogs in the Federal District of Brazil.

METHODS

Ticks were dissected to remove their intestines and salivary glands for DNA extraction and the subsequent amplification of the conserved region of 120 bp of kDNA and 234 bp of the hsp70 gene of Leishmania spp. The amplified kDNA products were digested with endonucleases HaeIII and BstUI and were submitted to DNA sequencing. Isolated Leishmania parasites from these ticks were analyzed by multilocus enzyme electrophoresis, and the DNA obtained from this culture was subjected to microsatellite analyses.

RESULTS

Overall, 130 specimens of R. sanguineus were collected from 27 dogs. Leishmania spp. were successfully isolated in culture from five pools of salivary glands and the intestines of ticks collected from four dogs. The amplified kDNA products from the dog blood samples and from the tick cultures, when digested by HaeIII and BstUI, revealed the presence of L. braziliensis and L. infantum. One strain was cultivated and characterized as L. infantum by enzyme electrophoresis. The amplified kDNA products from the blood of one dog showed a sequence homology with L. braziliensis; however, the amplified kDNA from the ticks collected from this dog showed a sequence homology to L. infantum.

CONCLUSION

The results confirm that the specimens of R. sanguineus that feed on dogs naturally infected by L. infantum contain the parasite DNA in their intestines and salivary glands, and viable L. infantum can be successfully isolated from these ectoparasites.

Participation of ticks in the infectious cycle of canine visceral leishmaniasis, in Teresina, Piauí, Brazil

In this study, we detected Leishmania spp. infection in R. sanguineus collected from dogs that were naturally infected with L. (L.) infantum. We examined 35 dogs of both sexes and unknown ages. The infected dogs were serologically positive by the immunofluorescence antibody test (IFAT), enzyme-linked immunosorbent assay (ELISA), and Quick Test-DPP (Dual Path Platform), as well as parasitological examination of a positive skin biopsy or sternal bone marrow aspiration. Ten negative dogs were included as controls. The ticks that infested these dogs were collected in pools of 10 adult females per animal. The PCR was performed with specific primers for Leishmania spp., which amplified a 720-bp fragment. Of the 35 analyzed samples, a product was observed in eight samples (8/35; 22.9%). We conclude that the presence of parasite DNA suggests that ticks participate in the zoonotic cycle of canine visceral leishmaniasis, in the city of Teresina, Piauí.

Ecology of phlebotomine sand flies and Leishmania infantum infection in a rural area of southern Italy

Phlebotomine sand flies are insects of major medico-veterinary significance in the Mediterranean region, as they may transmit pathogens to animals and humans, including viruses and protozoa. The present study was conducted in southern Italy, in an area where visceral leishmaniasis caused by Leishmania infantum is endemic. Insects were collected monthly during two consecutive years using light traps set in five different ecologic contexts (i.e., a stonewall near a woodhouse, a tree near volcanic rocks in a high-altitude area, a tree trunk in a meadow habitat, a sheep stable, and a chicken coop) and weekly in one site (the garage of a private house). A total of 13,087 specimens were collected and six species identified (i.e., Phlebotomus perfiliewi, Phlebotomus perniciosus, Phlebotomus neglectus, Phlebotomus papatasi, Phlebotomus mascittii, and Sergentomyia minuta), representing 75% of the total number of phlebotomine species found in Italy. P. perfiliewi was the most abundant species, comprising 88.14% of the specimens identified. The greatest species diversity and abundance was recorded in human dwellings and in animal sheds. Sand flies were active from June to October, peaking in July-August in 2010 and July-September in 2011. Part of the females (n=8865) was grouped into 617 pools (range, 1-10 insects each) according to species, feeding status, day and site of collection. A total of four pools (10 non-engorged specimens each) and one engorged female of P. perfiliewi were positive for L. infantum. This study confirms that phlebotomine vectors in southern Italy are highly adapted to human-modified environments (e.g., animal sheds) and that P. perfiliewi is a major vector of L. infantum in some regions of southern Italy.

Tick-borne infections of animals and humans: a common ground

A wide variety of pathogens is transmitted from ticks to vertebrates including viruses, bacteria, protozoa and helminths, of which most have a life cycle that requires passage through the vertebrate host. Tick-borne infections of humans, farm and companion animals are essentially associated with wildlife animal reservoirs. While some flying insect-borne diseases of humans such as malaria, filariasis and Kala Azar caused by Leishmania donovani target people as their main host, major tick-borne infections of humans, although potentially causing disease in large numbers of individuals, are typically an infringement of a circulation between wildlife animal reservoirs and tick vectors. While new tick-borne infectious agents are frequently recognised, emerging agents of human tick-borne infections were probably circulating among wildlife animal and tick populations long before being recognised as clinical causes of human disease as has been shown for Borrelia burgdorferi sensu lato. Co-infection with more than one tick-borne infection is common and can enhance pathogenic processes and augment disease severity as found in B. burgdorferi and Anaplasma phagocytophilum co-infection. The role of wild animal reservoirs in co-infection of human hosts appears to be central, further linking human and animal tick-borne infections. Although transmission of most tick-borne infections is through the tick saliva, additional routes of transmission, shown mostly in animals, include infection by oral uptake of infected ticks, by carnivorism, animal bites and transplacentally. Additionally, artificial infection via blood transfusion is a growing threat in both human and veterinary medicine. Due to the close association between human and animal tick-borne infections, control programs for these diseases require integration of data from veterinary and human reporting systems, surveillance in wildlife and tick populations, and combined teams of experts from several scientific disciplines such as entomology, epidemiology, medicine, public health and veterinary medicine.

First assessment for the presence of phlebotomine vectors in Bavaria, Southern Germany, by combined distribution modeling and field surveys

Leishmaniasis is caused by protozoa of the genus Leishmania and transmitted by sand flies from mammalian reservoirs to humans. In recent years, a northward spread of L. infantum from highly endemic Mediterranean countries into previously non-endemic Central European areas has been suspected based on presumed sporadic cases of autochthonous leishmaniasis. Here, we investigated whether sand flies are prevalent in Bavaria in Southern Germany, a federal state in which autochthonous cases have previously been reported. Considering the present and future climatic conditions, we determined whether Bavaria is suitable for five sand fly species with assumed spreading tendencies towards Central Europe: Phlebotomus ariasi, P. neglectus, P. perfiliewi and P. perniciosus that are known vectors for Leishmania in Europe, and P. mascittii, a suspected but not proven vector. Within Bavaria we defined sampling regions based on their climatic suitability and their spatial distance to the sites of the autochthonous cases and/or to areas of reported sand fly detection in states adjacent to Bavaria. At 155 locations in 7 sampling regions, CDC light traps were placed during 38 nights in the summers of 2009 and 2010, resulting in 202 trap-nights. All traps were negative for sand flies. The results suggest that Bavaria is not yet endemic for sand flies, but do not exclude the possibility of sporadic cases of autochthonous human or zoonotic Leishmania infections. This study, which combined methodological approaches from different disciplines, serves as reference for future surveys and risk analyses of sand flies and leishmaniasis in so far non-endemic areas of Europe.

Detection of Leishmania infantum in animals and their ectoparasites by conventional PCR and real time PCR

Visceral leishmaniosis (VL) is a parasitic disease caused by Leishmania infantum, which is primarily transmitted by phlebotomine sandflies. However, there has been much speculation on the role of other arthropods in the transmission of VL. Thus, the aim of this study was to assess the presence of L. infantum in cats, dogs and their ectoparasites in a VL-endemic area in northeastern Brazil. DNA was extracted from blood samples and ectoparasites, tested by conventional PCR (cPCR) and quantitative real time PCR (qPCR) targeting the L. infantum kinetoplast DNA. A total of 280 blood samples (from five cats and 275 dogs) and 117 ectoparasites from dogs were collected. Animals were apparently healthy and not previously tested by serological or molecular diagnostic methods. Overall, 213 (76.1 %) animals and 51 (43.6 %) ectoparasites were positive to L. infantum, with mean parasite loads of 795.2, 31.9 and 9.1 fg in dogs, cats and ectoparasites, respectively. Concerning the positivity between dogs and their ectoparasites, 32 (15.3 %) positive dogs were parasitized by positive ectoparasites. The overall concordance between the PCR protocols used was 59.2 %, with qPCR being more efficient than cPCR; 34.1 % of all positive samples were exclusively positive by qPCR. The high number of positive animals and ectoparasites also indicates that they could serve as sentinels or indicators of the circulation of L. infantum in risk areas.

Tick parasites of rodents in Romania: host preferences, community structure and geographical distribution

Background

Ticks are among the most important vectors of zoonotic diseases in temperate regions of Europe, with widespread distribution and high densities, posing an important medical risk. Most ticks feed on a variety of progressively larger hosts, with a large number of small mammal species typically harbouring primarily the immature stages. However, there are certain Ixodidae that characteristically attack micromammals also during their adult stage. Rodents are widespread hosts of ticks, important vectors and competent reservoirs of tick-borne pathogens. Micromammal-tick associations have been poorly studied in Romania, and our manuscript shows the results of a large scale study on tick infestation epidemiology in rodents from Romania.

Methods

Rodents were caught using snap-traps in a variety of habitats in Romania, between May 2010 and November 2011. Ticks were individually collected from these rodents and identified to species and development stage. Frequency, mean intensity, prevalence and its 95% confidence intervals were calculated using the EpiInfo 2000 software. A p value of <0.05 was considered statistically significant.

Results

We examined 423 rodents (12 species) collected from six counties in Romania for the presence of ticks. Each collected tick was identified to species level and the following epidemiological parameters were calculated: prevalence, mean intensity and mean abundance. The total number of ticks collected from rodents was 483, with eight species identified: Ixodes ricinus, I. redikorzevi, I. apronophorus, I. trianguliceps, I. laguri, Dermacentor marginatus, Rhipicephalus sanguineus and Haemaphysalis sulcata. The overall prevalence of tick infestation was 29.55%, with a mean intensity of 3.86 and a mean abundance of 1.14. Only two polyspecific infestations were found: I. ricinus + I. redikorzevi and I. ricinus + D. marginatus.

Conclusions

Our study showed a relatively high diversity of ticks parasitizing rodents in Romania. The most common tick in rodents was I. ricinus, followed by I. redikorzevi. Certain rodents seem to host a significantly higher number of tick species than others, the most important within this view being Apodemus flavicollis and Microtus arvalis. The same applies for the overall prevalence of tick parasitism, with some species more commonly infected (M. arvalis, A. uralensis, A. flavicollis and M. glareolus) than others. Two rodent species (Mus musculus, Rattus norvegicus) did not harbour ticks at all. Based on our results we may assert that rodents generally can act as good indicators for assessing the distribution of certain tick species.

Seroprevalence and asymptomatic carriage of Leishmania spp. in Austria, a non-endemic European country

Leishmaniasis is a rare disease in Central Europe and is diagnosed almost exclusively in travellers or migrants coming from tropical or subtropical countries. We conducted an explorative cross-sectional serological study, using a commercial ELISA, in 1048 healthy Austrian individuals to assess the distribution of specific antibodies against Leishmania spp. in humans in Austria. Overall, 47 individuals (4.5%) tested positive, and an additional 32 (3.1%) showed borderline results. After 12 months, sera from 42 of the 79 individuals who had initially tested seropositive/borderline were tested by ELISA a second time: 18 were persistently positive, nine were borderline. Those whose sera were persistently positive/borderline were then screened for potential carrier status using a commercial oligochromatographic PCR test to detect parasite DNA. Four samples were PCR positive and were subjected to a second PCR allowing parasite identification after DNA sequencing: two samples were identified as Leishmania donovani/infantum complex and Leishmania (Viannia) guyanensis, respectively. Epidemiological information was obtained with a questionnaire: no correlation was found for the number of holiday trips within the previous 6 months, but a significant risk of exposure to Leishmania spp. was found for travel to the New World, particularly to the Caribbean. Our data demonstrate that Leishmania spp. seroprevalence in non-endemic countries has been considerably underestimated.

Detection of Leishmania infantum DNA mainly in Rhipicephalus sanguineus male ticks removed from dogs living in endemic areas of canine leishmaniosis

BACKGROUND

Sand flies are the only biologically adapted vectors of Leishmania parasites, however, a possible role in the transmission of Leishmania has been proposed for other hematophagous ectoparasites such as ticks. In order to evaluate natural infection by Leishmania infantum in Rhipicephalus sanguineus ticks, taking into account its close association with dogs, 128 adult R. sanguineus ticks removed from 41 dogs living in endemic areas of canine leishmaniosis were studied.

METHODS

Individual DNA extraction was performed from each tick and whole blood taken from dogs. Dog sera were tested for IgG antibodies to L. infantum antigen by ELISA and L. infantum real-time PCR was performed from canine whole blood samples and ticks.

RESULTS

Leishmania infantum PCR was positive in 13 ticks (10.1%) including one female, (2.0%) and 12 males (15.2%), and in only five dogs (12.2%). Male ticks had a significantly higher infection rate when compared to female R. sanguineus. The percentage of L. infantum seroreactive dogs was 19.5%. All but two PCR positive dogs were seroreactive. Leishmania infantum PCR positive ticks were removed from seropositive and seronegative dogs with a variety of PCR results.

CONCLUSIONS

This study demonstrates high prevalence of L. infantum DNA in R. sanguineus ticks removed from L. infantum seropositive and seronegative dogs. The presence of L. infantum DNA was detected mainly in male ticks possibly due to their ability to move between canine hosts and feed on several canine hosts during the adult life stage. Additional studies are needed to further explore the role of R. sanguineus ticks and in particular, male adults, in both the epidemiology and immunology of L. infantum infection in dogs in endemic areas.

LeishVet guidelines for the practical management of canine leishmaniosis

The LeishVet group has formed recommendations designed primarily to help the veterinary clinician in the management of canine leishmaniosis. The complexity of this zoonotic infection and the wide range of its clinical manifestations, from inapparent infection to severe disease, make the management of canine leishmaniosis challenging. The recommendations were constructed by combining a comprehensive review of evidence-based studies, extensive clinical experience and critical consensus opinion discussions. The guidelines presented here in a short version with graphical topic displays suggest standardized and rational approaches to the diagnosis, treatment, follow-up, control and prevention of canine leishmaniosis. A staging system that divides the disease into four stages is aimed at assisting the clinician in determining the appropriate therapy, forecasting prognosis, and implementing follow-up steps required for the management of the leishmaniosis patient.