Luciana Aguiar Figueredo

Rhipicephalus sanguineus (Acari: Ixodidae), the brown dog tick, parasitizing humans in Brazil

The objective of this paper is to describe four cases of human parasitism by Rhipicephalus sanguineus (Latrielle) in Brazil. During an investigation regarding the species of ectoparasites of domestic dogs from the metropolitan region of Recife, Pernambuco state, four dog owners were found to be parasitized by ticks. The ticks were collected from these individuals and their dogs. All the ticks were identified as Rhipicephalus sanguineus . These are, to our knowledge, the first four cases of human parasitism by this tick species in Brazil. The possible implications of this finding are discussed here.

Detection of Leishmania infantum in Rhipicephalus sanguineus ticks from Brazil and Italy

Canine leishmaniosis is a widespread disease caused by Leishmania parasites, which are transmitted by phlebotomine sand flies. However, in some areas where canine leishmaniosis is endemic, but the primary vectors have not been found, ticks have been suspected to play a role in transmitting the infection. Herewith, we report the detection of Leishmania infantum kinetoplast minicircle DNA (kDNA) in ticks collected from naturally infected dogs living in rural areas of Southern Italy (site A) and Northeastern Brazil (site B). Between March and October 2007, ticks were collected from 26 dogs positive to anti-Leishmania antibodies (one from site A and 25 from site B) and either placed directly into vials containing 70% ethanol or maintained alive for identification and subsequent dissection. All the 95 ticks collected were morphologically identified as Rhipicephalus sanguineus. After identification, their genomic DNA was extracted (either individually or in pools) and processed by polymerase chain reaction (PCR) for the detection of L. infantum kDNA. Two pools of salivary glands from ticks (one from five females and other from five males) found on a dog from site A and tested by a conventional PCR were positive. Amplicon sequencing confirmed the identity of the parasite. In addition, nine (12.3%) out of the 73 ticks found on dogs from site B and tested by a real-time PCR were positive, with a low parasite load (less than 1 parasite/ml). The retrieval of L. infantum kDNA in salivary glands of R. sanguineus ticks has been here reported for the first time. Therefore, further studies are needed to assess the competence of ticks as vectors of Leishmania parasites from dog to dog.

Fungal diseases of horses.

Among diseases of horses caused by fungi (=mycoses), dermatophytosis, cryptococcosis and aspergillosis are of particular concern, due their worldwide diffusion and, for some of them, zoonotic potential. Conversely, other mycoses such as subcutaneous (i.e., pythiosis and mycetoma) or deep mycoses (i.e., blastomycosis and coccidioidomycosis) are rare, and/or limited to restricted geographical areas. Generally, subcutaneous and deep mycoses are chronic and progressive diseases; clinical signs include extensive, painful lesions (not pathognomonic), which resemble to other microbial infections. In all cases, early diagnosis is crucial in order to achieve a favorable prognosis. Knowledge of the epidemiology, clinical signs, and diagnosis of fungal diseases is essential for the establishment of effective therapeutic strategies. This article reviews the clinical manifestations, diagnosis and therapeutic protocols of equine fungal infections as a support to early diagnosis and application of targeted therapeutic and control strategies.

Cutaneous and visceral leishmaniosis in dogs from a rural community in northeastern Brazil.

A community-based epidemiological study was carried out in a rural area in northeastern Brazil, where visceral leishmaniasis is endemic, but the primary vector Lutzomyia longipalpis has never been found. Forty-one dogs were screened by an indirect immunofluorescence antibody test (IFAT) for the presence of anti-Leishmania antibodies and 12 (29.3%) of them were positive. One of the IFAT-positive dogs was also positive for Leishmania amastigotes in bone marrow cytology and for Leishmania infantum by real-time polymerase chain reaction (PCR) on blood. One IFAT-negative dog was positive for L. infantum by PCR on bone marrow and other for Leishmania amastigotes in skin stained-smears. When tested for L. braziliensis by PCR, 20 dogs were positive. Considering all diagnostic tests, the estimated prevalence of Leishmania spp. infection in the studied rural dog population was 58.5%. There was no significant difference in IFAT-positivity in relation to age, gender, and clinical status of the dogs. When tested for L. infantum by real-time PCR, 20 ticks collected from IFAT-positive dogs were all negative. This study shows a high level of exposure to Leishmania spp. infection in dogs from a rural community in northeastern Brazil. In general, the results do not support the participation of ticks as vectors of L. infantum in this area, which is likely to be transmitted by Lutzomyia spp. other than L. longipalpis. Finally, this study highlights that the use of IFAT in areas where both L. infantum and L. braziliensis are present should be withdraw in order to avoid the unnecessary culling of dogs that are actually infected only by L. braziliensis.

Seasonal variation in the effect of climate on the biology of Rhipicephalus sanguineus in southern Europe

OBJECTIVE Rhipicephalus sanguineus is the most widespread tick in the world and a vector of many pathogens infecting dogs and humans. To date, there have been no investigations on the biology of R. sanguineus under natural Mediterranean climatic conditions. METHODS The biology of R. sanguineus was studied under laboratory and natural climatic conditions in southern Italy. Several biological parameters were compared in different seasons, and their correlation with climatic data was assessed. RESULTS The life cycle of R. sanguineus lasted for a mean of 101·4 and 116·2 days under laboratory and environmental conditions respectively. Reproductive parameters of wild-collected females kept in the environment in May were significantly different from first-generation females maintained in September-October, and the correlation between reproductive parameters and climate data varied according to season. CONCLUSION These results indicate that the Mediterranean climate affects the biology of R. sanguineus, which compensates its losses during the initial phases of its cycle in spring with high feeding and moulting rates of larvae and nymphs during summer as well as with high egg production during autumn. These results advance our knowledge of the biology of R. sanguineus and will be useful for the understanding of the eco-epidemiology of tick-borne diseases that this tick transmits.

Molecular identification and phylogenesis of dermatophytes isolated from rabbit farms and rabbit farm workers

Little information is available on the molecular epidemiology of dermatophytoses in rabbit farms and farm workers. A total of 117 isolates belonging to the Trichophyton mentagrophytes complex and 21 isolates of Microsporum canis were collected from rabbits with or without skin lesions, air samples of farms known to harbour these pathogens, and from farm workers with skin lesions, and molecularly characterized. Sequencing of amplicons from the T. mentagrophytes complex and M. canis isolates revealed the presence of one sequence-type for both partial chitin synthase-1 gene (pchs-1) and ribosomal internal transcribed spacer (ITS+), respectively. On the basis of comparative sequence analyses, isolated representing the T. mentagrophytes complex were molecularly identified as Trichophyton interdigitale (zoophilic) Priestley. The M. canis and T. interdigitale pchs-1 sequences herein analysed were 100% homologous to known sequences from different hosts (i.e., cats, dogs, humans and rabbits). Conversely, the ITS+ sequences of T. interdigitale from dogs, pigs and mice were identical, but displayed up to 8.6% difference with those from humans, guinea pigs and rabbits. The results of this study suggest that environmental and clinical isolates of T. interdigitale (zoophilic) and M. canis might share a common origin. Interestingly, the close phylogenetic relationship between T. interdigitale (zoophilic) strains and isolates from dogs, pigs and mice might indicate that these animals represented a reservoir of dermatophyte infection in rabbit farms. These animal species should therefore be considered when setting up control protocols to prevent infections by dermatophytes and their zoonotic transmission.

Occurrence of antibodies to Neospora caninum and Toxoplasma gondii in dogs from Pernambuco, Northeast Brazil

A serological survey was carried out to assess the occurrence of anti-Neospora caninum antibodies in dogs from the State of Pernambuco. A total of 625 serum samples of dogs (289 from Paulista, 168 from Amaraji and 168 from Garanhuns) were tested by an immunofluorescence antibody assay for the detection of anti-N. caninum antibodies. A total of 177 (28.3%; IC 95%, 24.9-32.1) samples were positive. The seropositivity rates found in Paulista, Amaraji and Garanhuns were 26% (IC 95%, 21-31.4), 26.2% (IC 95%, 19.7-33.5) and 34.5% (IC 95%, 27.4-42.2), respectively. Of the 177 serum samples positive to anti-N. caninum antibodies, 170 were additionally tested for the presence of anti-Toxoplasma gondii antibodies and out of these 57.6% (IC 95%, 49.8-65.2) were positive. The results indicate that dogs from Amaraji, Paulista and Garanhuns are exposed to both N. caninum and T. gondii infections. The presence of dogs infected by N. caninum in Pernambuco represents a potential risk factor for the occurrence of outbreaks of abortion in cattle and small ruminants in this state. This study is the largest serological survey on the presence of anti-N. caninum antibodies in dogs carried out in Brazil and reports for the first time the exposure to N. caninum and T. gondii in dogs from Pernambuco.

Transovarial passage of Leishmania infantum kDNA in artificially infected Rhipicephalus sanguineus

Phlebotomine sand flies are the only proven biological vectors of Leishmania parasites. However, Rhipicephalus sanguineus ticks have long been suspected to transmit Leishmania infantum in studies carried out in laboratory and natural conditions. In the present study, 5 microl of L. infantum promastigotes (1x10(6) cells per ml) was injected into the hemocel through the coxa I of four engorged females (F1, F2, F3 and F4). Control ticks (F5 and F6) were injected with sterile phosphate-buffered saline (PBS) using the same procedure. Then, these females, their eggs, and the originated larvae were tested by real time polymerase chain reaction (real-time PCR) for the presence of L. infantum kinetoplast DNA (kDNA). Females and eggs were tested after the end of the oviposition period (about 5 weeks post-inoculation) whereas larvae were tested about 4 months after the inoculation of females. All artificially infected females were positive for L. infantum kDNA. In addition, two pools of eggs (one from F2 and other from F4) and four pools of larvae (one from each F1 and F4 and two from F2) were positive for L. infantum kDNA. These results showed, for the first time, the transovarial passage of L. infantum kDNA in R. sanguineus ticks, thus suggesting that the transovarial transmission of L. infantum protozoa in ticks is worth to be investigated.

Effects of prolonged exposure to low temperature on eggs of the brown dog tick, Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae).

The widespread geographical distribution of the brown dog tick Rhipicephalus sanguineus (Acari: Ixodidae) is related to the cosmopolitan distribution of its primary host and to its adaptability to different environments, under variable climate conditions. Field studies have suggested that temperature is the most important factor driving the population dynamics of this tick species. In order to investigate the effects of prolonged exposure to low temperature on eggs of R. sanguineus, nine groups (II-X) of five egg batches each were maintained at 8+/-2 degrees C (70+/-10% RH, and scotophase) for 15, 30, 45, 60, 75, 90, 105, 120, and 135 days. One group (group I) was maintained in the incubator (26+/-1 degrees C, 70+/-10% RH, and scotophase) and used as control. The mean egg incubation period from group I was 11.6+/-0.5 days, with an egg hatch rate of 99.5+/-0.5%. Conversely, no egg hatched at 8 degrees C. Exposure to cold showed a strong positive correlation with egg incubation period (r=0.99) as well as a strong negative correlation with egg hatch rate (r=-0.95) and larval longevity (r=-0.99). Overall, the present results points out that R. sanguineus eggs are sensible to prolonged exposure to low temperature, which is definitely a major limiting factor for the establishment of populations of this tick in cold temperate regions.

Clinical and hematological findings in Leishmania braziliensis-infected dogs from Pernambuco, Brazil

Canine cutaneous leishmaniasis by Leishmania braziliensis is a neglected, but widespread disease of dogs in South America. This paper describes clinical and hematological alterations in 17 L. braziliensis-infected dogs from Brazil. The most common hematological findings were thrombocytopenia (82.4%), anemia (70.6%), low packed cell volume (52.9%) and eosinophilia (41.2%). Twelve (70.6%) dogs displayed at least one evident physical alteration; 11 dogs (64.7%) presented skin lesions, four (23.5%) had weight loss and two (11.8%) onychogryphosis. L. braziliensis-infected dogs present clinical and hematological signs often observed in dogs infected by other pathogens. This indicates that veterinarians and public health workers should not consider the presence of non-specific clinical signs as diagnostic criteria for visceral leishmaniasis in dogs living endemic areas to avoid misdiagnosis and subsequent elimination of dogs infected by L. braziliensis.