Dirofilaria immitis and Onchocercidae spp. in wild felids from Brazil.

Among the species described within the Onchocercidae family, Dirofilaria immitis is regarded as the most common worldwide, causing severe and often fatal conditions in dogs, cats, and occasionally humans. Dirofilaria spp. are vectored by mosquitoes, simulids, and culicoids, with their epidemiology dependent on the geographical distribution of competent vectors. Eight species of Dirofilaria have been reported so far in Brazil, of which six parasitize non-human primates, deer, procyonids, and marsupials. Here, we investigated the occurrence of Onchocercidae in wild felids (i.e., Panthera onca, Puma concolor, Herpailurus yagouaroundi, Leopardus geoffroyi, Leopardus guttulus, Leopardus pardalis, Leopardus wiedii, Leopardus munoai) from different locations in Brazil. Overall, 82 samples (n = 63 blood; n = 19 tissues) were molecularly screened for cytochrome c oxidase subunit-1 (cox1) gene. Four (i.e., 4.8%) wild felid samples were positive, and at BLAST analysis, the obtained sequences showed varying percentage of nucleotide identity with the genera Brugia (i.e., 87-88%), Setaria (i.e., 89%), and D. immitis (i.e., 94.4%). Phylogenetic analyses clustered sequences obtained into three distinct clades, one with D. immitis and the remaining two with other Onchocercidae spp. Data herein obtained highlight the need for a more comprehensive understanding of the diversity and biology of Onchocercidae in South America in order to assess the potential impact that these species may have for domestic and wild animals, as well as humans.

Filarial Nematodes in Dogs from the Northeast Region of Brazil.

PURPOSE: Medical and veterinary filarial nematodes are transmitted by blood-feeding vectors. In dogs, these parasites are mainly represented by nematodes in which microfilariae dwell in the blood (Dirofilaria spp. and Acanthocheilonema spp.) or skin (Cercopithifilaria spp. and Onchocerca lupi). The aim of this study was to determine the prevalence of these filarial infections in dogs residing in a touristic, heavily populated location in the northeastern region of Brazil. METHODS: Blood samples (n = 245) were assessed by a modified Knott test, followed by a qualitative ELISA test (SNAP® 4Dx® Plus, IDEXX Laboratory, Westbrook, Maine, USA) for the detection of antibodies against Anaplasma spp., Borrelia burgdorferi sensu lato, Ehrlichia spp. and antigens of Dirofilaria immitis. Skin samples (n = 71) were microscopically examined and molecularly assessed through a PCR targeting the 12 S rRNA gene. RESULTS: Microfilariae and antigen of D. immitis were detected simultaneously in 15 (6.1%; 95% CI = 3.7-9.8) animals. Nine animals (3.6%; 95% CI = 1.9-6.8) were D. immitis antigen positive but microfilariae negative and nine other animals (3.6%; 95% CI = 1.9-6.8) were microfilariae positive but D. immitis antigen negative. D. immitis positive dogs were found in four different municipalities. No filarioids were detected in the skin after microscopical and molecular analyses. CONCLUSION: Data from this study demonstrate that D. immitis is the main filarial nematode infecting dogs in coastal areas in northeastern Brazil. Based on the potential risk of infection in which animals are submitted, it is essential to perform tests to detect microfilariae and D. immitis antigen. Preventive measures must be adopted by using microfilaricidal compounds and anti-feeding insecticides to prevent canine infection.

Prevention of heartworm infection in dogs using a combination of moxidectin, imidacloprid and praziquantel: evidence from a randomized clinical trial.

The aim of this study was to evaluate the efficacy of a topical combination of moxidectin 3.5%, imidacloprid 10% and praziquantel 10% for the prevention of Dirofilaria immitis (Leidy, 1856) infection in dogs. For this purpose, a randomized and controlled clinical trial was conducted between August 2021 and October 2022, in the municipality of Goiana, state of Pernambuco, north-eastern Brazil, where heartworm is highly prevalent. Of the 213 dogs initially sampled (baseline), 68 (31.9%) were positive for adult antigens (SNAP 4Dx Plus, Idexx) and/or microfilariae (modified Knott's test). On day 0, 140 negative dogs were randomly included in the treatment and control groups, 70 animals each. During the study, 60 dogs (34 treated and 26 untreated) were removed for different reasons. At the end of the study (day 360 ± 2), 36 treated and 44 untreated were sampled and included in the efficacy calculation. The efficacy against the development of adults and microfilariae was 84.7%, with only one treated dog being positive for adult antigens but negative for microfilariae. On the other hand, eight untreated dogs were positive for adult antigens and/or microfilariae, resulting in a significant difference in the number of positives between groups (Chi-square test = 4.706, df = 1, P = 0.0301). Remarkably, the efficacy against the appearance of D. immitis microfilariae was 100% (i.e., all treated dogs negative) and three untreated dogs were positive for microfilariae. The topical combination of moxidectin 3.5%, imidacloprid 10% and praziquantel 10% significantly reduced the risk of D. immitis infection in treated dogs as compared with untreated dogs, in a highly endemic area in north-eastern Brazil.

First molecular characterization of Dirofilaria Immitis in Cuba.

BACKGROUND: Dirofilarioses are widespread diseases caused by mosquito-borne nematodes of the family Onchocercidae, genus Dirofilaria. The major etiologic agent of canine dirofilariosis in the American continent is the zoonotic parasite Dirofilaria immitis. Existing reports of filarioid nematodes in Cuba are based solely on morphological and immunological analysis which do not allow unambiguous identification and/or direct detection of causal agents. RESULTS: Here we present the molecular characterization of filarioid nematodes found in a dog in Cuba. Based on the molecular and phylogenetic analysis of the 5.8S-ITS2-28S region and cox1 gene fragments, the worms were unambiguously classified as D. immitis. Sequence analysis showed high identity of the gene fragments in this study with others previously obtained from D. immitis found in dogs, wolfs and jackals but also from mosquito vectors of D. immitis. CONCLUSIONS: Further studies are guarantee to better understand the epidemiological impact of canine dirofilariosis in Cuba as well as the competence of different species of culicid mosquitoes as vectors of Dirofilaria in the country.

Dirofilaria immitis in pet dogs from the metropolitan area of the Colombian Caribbean.

A cross-sectional study was carried out to determine the frequency and factors associated with Dirofilaria immitis infection in pet dogs in the metropolitan area of the Colombian Caribbean (northern Colombia). A total of 173 dogs were analyzed by a commercial rapid immunochromatographic test (RIT) and a nested PCR of the cytochrome oxidase subunit I gene, in parallel. Ninety-two (53.2%) of the dogs showed positive results to the RIT, while 59 (34.1%) animals had D. immitis DNA by PCR. Positivity to one or both diagnostic techniques was detected in 104 (60.1%; CI95%: 53.8-67.4) of the sampled dogs. In PCR-positive dogs, phylogenetic analyses evidenced high nucleotide identity (100%) with sequences previously obtained from mosquitoes, dogs and other mammals in different countries. Exercise intolerance (p = 0.002; OR: 2.33; CI95%: 1.37-3.96) and thrombocytopenia (p = < 0.001; OR: 1.95; CI95%: 1.11-3.43) were the main factors associated with D. immitis infection in dogs. The high frequency of D. immitis in dogs indicates a wide distribution of this parasite in the metropolitan area of the Colombian Caribbean, which can be of animal and public health concern. Our results highlight the need to combine different methods to increase the diagnostic accuracy of D. immitis.

The first report of Dirofilaria repens infection in dogs from Colombia.

Dirofilariasis is a mosquito-borne disease caused by Dirofilaria parasites, affecting both wild and domestic animals, including humans considered as accidental hosts. Dirofilaria repens is the principal causative agent of dirofilariasis in the Old World, with increasing reports of the parasite in countries where it has not been previously identified, due to several factors such as the expansion of mosquito vectors' geographical distribution. By utilizing newly designed primers for molecular detection and confirming through next-generation sequencing, here, we report the first plausible cases of D. repens in dogs from Colombia. Our results support the classification of this species as an emergent pathogen in the Americas. Finally, we encourage an increase in diagnostic and surveillance efforts to prevent and control the current and future dirofilariasis cases in this region.

Subcutaneous dirofilariasis due to Dirofilaria immitis in a dog in Brazil: first report.

The aim of this study was to report on the presence of microfilariae of Dirofilaria immitis causing nodular pyogranulomatous dermatitis in a dog in the state of Rio Grande do Norte, northeastern Brazil. A 4-year-old male dachshund dog with lesions in the nostrils and left dorsolateral regions was treated. Tests were requested to aid in making the diagnosis, such as skin cytology, Knott's test, thick smear and histopathology of the lesions. From these, presence of a diffuse pyogranulomatous process was observed and, amidst the cellular material, microfilariae of Dirofilaria spp. A conventional polymerase chain reaction test on tissue samples from the lesions revealed the presence of the species D. immitis. Treatment based on ivermectin (3mg) was administered at a single oral dose of 0.6 mg/kg. In the first seven days there was regression of the lesions, but after 30 days there was recurrence. A new treatment was administered, consisting of 10% imidacloprid + 2.5% moxidectin (4-10 mg/kg), with one application per month for 6 months, and doxycycline (100 mg), 10 mg/kg, 1 tablet, 2 times a day, for 30 days. In conclusion, D. immitis microfilariae caused pyogranulomatous lesions in the subcutaneous tissue of a dog. This had not previously been described in Brazil.

Dirofilaria immitis is endemic in rural areas of the Brazilian Amazonas state capital, Manaus.

The canine filarial parasite Dirofilaria immitis has not been reported in Brazil´s Amazonas state capital, Manaus, for over a century. Here, we report one imported and 27 autochthonous D. immitis infections from a microfilarial survey of 766 domestic dog blood samples collected between 2017 and 2021 in Manaus. An Overall prevalence estimate of 15.44% (23/149) was calculated from our two rural collection sites; a prevalence of 1.22% (4/328) was estimated at our periurban collection site, and an overall prevalence of 0.35% (1/289) was calculated from our two urban clinic collections. Our data suggest that in the urban areas of Manaus, where the parasites are very likely vectored by the same species of mosquito that historically vectored Wuchereria bancrofti (Culex quinquefasciatus), prevalence levels are very low and possibly maintained by an influx from rural areas where sylvatic reservoirs and/or more favorable vector transmission dynamics maintain high prevalences.

Heartworm adulticide treatment: a tropical perspective.

Dirofilaria immitis (the canine heartworm) is widespread in the tropics, with prevalence surpassing 30% in high-risk areas. In addition to the suitable climatic conditions that favour mosquito abundance and filarial larva development, there is low compliance with the recommended year-round use of preventives in these transmission hotspots. This represents a major concern, considering that melarsomine (first-line heartworm adulticide) is unavailable in several tropical countries, resulting in the so-called slow-kill protocol being the only available adulticide treatment option. In this article, the members of TroCCAP (Tropical Council for Companion Animal Parasites) review the current distribution of heartworm in the tropics and the availability of melarsomine, and discuss alternatives for the management of heartworm infections in dogs.

Dirofilaria immitis parasite infection in cats: first case reported in the Legal Amazon region, Brazil: case report / Infecção por Dirofilaria immitis em gato: primeiro registro na região da Amazônia Legal, Brasil: relato de caso

A case of infection with Dirofilaria immitis in a cat is reported here with clinical signs of apathy, anorexia, dyspnea, polypnea, slight dehydration and pale mucus membranes. The radiographic examination showed cardiomegaly, lobar arteries dilation of the cranial lobes and tortuosity, enlargement of the caudal lobar arteries. In the right lobe of the lung parenchyma, interstitial pulmonary opacification tending to alveolar opacification was seen. The clinical signs, the movements, and the morphology of the microfilariae in the direct examination of fresh blood, peripheral blood smear and Knott's modified test supported the diagnosis. We alert to the need for clinicians to consider feline heartworm diseases as a differential diagnosis in endemic areas when cats show respiratory signs.

Descreve-se um caso de infecção por Dirofilaria immitis em gato com sinais clínicos de apatia, anorexia, dispneia, polipneia, leve desidratação e mucosas pálidas. O exame radiográfico demonstrou cardiomegalia, dilatação da artéria lobar cranial e tortuosidade, alargamento dos lobos caudais da artéria lobar. No lobo direito do parênquima pulmonar, opacificação pulmonar intersticial tendendo à opacificação foi observada. O diagnóstico foi baseado nos sinais clínicos, nos movimentos e na morfologia das microfilárias detectadas no exame de sangue a fresco, no esfregaço de sangue periférico e no teste de Knott modificado. Alertou-se para a necessidade de os clínicos considerarem a dirofilariose felina como diagnóstico diferencial em áreas endêmicas quando os gatos apresentam sinais respiratórios.

Parasitism of Dirofilaria incrassata Molin, 1858 in coatis (Nasua nasua).

Populations of the coati, Nasua nasua, like the populations of other wild animals, are regulated by several biotic or abiotic factors. For example, parasites act as a biotic factor affecting the dynamics and density of coati populations. The parasitic nematodes of coatis include Dirofilaria species, such as Dirofilaria immitis, Dirofilaria repens, and Dirofilaria incrassata. Considering that there are few records on parasitism by D. incrassata, including information on the life cycle or location in the host body, this study aimed to investigate the infection of N. nasua by D. incrassata in midwestern Brazil. Thus, two coatis (males and adults) from the Cerrado of Goiás, which died (cause unknown) at the Wild Animal Screening Center/IBAMA in the municipality of Goiânia, Goiás, Midwestern of Brazil, were dissected and all helminths found were collected, identified following specific keys and quantified. A total of 85 specimens of D. incrassata were collected, with a mean parasitic intensity of 42.5 and a parasitic amplitude ranging from 40 to 45, measuring 41-93 mm in length and 0.23-0.45 mm in width. All helminths were adults and were distributed in the superficial and deep fascia (at different levels) from the neck to the hind limb. Most helminths were tangled, with some encased in a connective tissue film. Most reported human heartworm cases refer to subcutaneous or ocular heartworm infection, mainly caused by D. repens, although other species of heartworm may be associated. D. incrassata was not reported as zoonotic agent, diferently of other Dirofilaria species associated with wild animals and with zoonotic potential in the Americas. This study reiterates N. nasua as the definitive host for D. incrassata and the subcutaneous tissue as the site of choice for this helminth in the adult form. In addition, it reports new body regions where the parasite occurs. This study is the first to document the occurrence of D. incrassata infestation in the State of Goiás, Brazil.

Dirofilaria immitis in Dog Imported from Venezuela to Chile.

We report a case of Dirofilaria immitis nematode infection in a dog imported from Venezuela that had been living for 2 years in Santiago, Chile, where this parasite had not been reported before. Our findings warrant surveillance for all dogs imported to Chile, given that suitable conditions exist for establishing this parasite.

Dirofilaria immitis is endemic in rural areas of the Brazilian Amazonas state capital, Manaus / Dirofilaria immitis é endêmica em áreas rurais da capital do estado do Amazonas, Manaus

The canine filarial parasite Dirofilaria immitis has not been reported in Brazil´s Amazonas state capital, Manaus, for over a century. Here, we report one imported and 27 autochthonous D. immitis infections from a microfilarial survey of 766 domestic dog blood samples collected between 2017 and 2021 in Manaus. An Overall prevalence estimate of 15.44% (23/149) was calculated from our two rural collection sites; a prevalence of 1.22% (4/328) was estimated at our periurban collection site, and an overall prevalence of 0.35% (1/289) was calculated from our two urban clinic collections. Our data suggest that in the urban areas of Manaus, where the parasites are very likely vectored by the same species of mosquito that historically vectored Wuchereria bancrofti (Culex quinquefasciatus), prevalence levels are very low and possibly maintained by an influx from rural areas where sylvatic reservoirs and/or more favorable vector transmission dynamics maintain high prevalences.(AU)

O parasita filarial canino, Dirofilaria immitis, causa doença zoonótica, mas não tem sido registrado em Manaus, capital do estado do Amazonas, há mais de um século. Neste trabalho, foi relatado uma infecção por D. immitis alóctone e 27 autóctones de um levantamento de microfilárias em 766 amostras de sangue em cães domésticos, coletados entre 2017 e 2021 em Manaus. A prevalência de 15,44% (23/149) foi estabelecida em áreas rurais, 1,22% (4/328) para áreas periurbanas e de 0,35% (1/289) para duas clínicas veterinárias localizadas na zona urbana da cidade. Estes dados sugerem, portanto, que nas áreas urbanas de Manaus, nas quais o parasita é provavelmente vetorizado pela mesma espécie de mosquito que, historicamente, transmitiu Wuchereria bancrofti (Culex quinquefasciatus). Também os níveis de prevalência são baixos e, possivelmente, mantidos por um influxo de áreas rurais onde reservatórios silvestres e/ou dinâmicas de transmissão vetorial mais favoráveis mantêm uma prevalência mais elevada.(AU)

Subcutaneous dirofilariasis due to Dirofilaria immitis in a dog in Brazil: first report / Dirofilariose subcutânea por Dirofilaria immitis em canino no Brasil: primeiro relato

The aim of this study was to report on the presence of microfilariae of Dirofilaria immitis causing nodular pyogranulomatous dermatitis in a dog in the state of Rio Grande do Norte, northeastern Brazil. A 4-year-old male dachshund dog with lesions in the nostrils and left dorsolateral regions was treated. Tests were requested to aid in making the diagnosis, such as skin cytology, Knott's test, thick smear and histopathology of the lesions. From these, presence of a diffuse pyogranulomatous process was observed and, amidst the cellular material, microfilariae of Dirofilaria spp. A conventional polymerase chain reaction test on tissue samples from the lesions revealed the presence of the species D. immitis. Treatment based on ivermectin (3mg) was administered at a single oral dose of 0.6 mg/kg. In the first seven days there was regression of the lesions, but after 30 days there was recurrence. A new treatment was administered, consisting of 10% imidacloprid + 2.5% moxidectin (4-10 mg/kg), with one application per month for 6 months, and doxycycline (100 mg), 10 mg/kg, 1 tablet, 2 times a day, for 30 days. In conclusion, D. immitis microfilariae caused pyogranulomatous lesions in the subcutaneous tissue of a dog. This had not previously been described in Brazil.(AU)

Resumo O objetivo deste trabalho foi relatar a presença de microfilárias de Dirofilaria immitis causando dermatite nodular piogranulomatosa em cão no estado do Rio Grande do Norte, região Nordeste do Brasil. Um cão de 4 anos, da raça Dachshund, foi atendido com lesões nas regiões das narinas e dorsolateral esquerda. Foram realizados exames de citologia cutânea, teste de Knott, gota espessa e histopatologia das lesões, sendo observada a presença de um processo piogranulomatoso difuso e microfilárias de Dirofilaria spp. Na reação em cadeia da polimerase convencional constatou-se a espécie D. immitis nas amostras de tecido das lesões. Foi efetuado um tratamento à base de Ivermectina (3mg) 0,6 mg/kg - 1 aplicação, via oral. Nos sete primeiros dias, houve regressão das lesões, porém, depois de 30 dias, houve recidiva. Foi efetuado um novo tratamento com imidacloprida 10% + moxidectina 2,5% (4-10 mg/kg), 1 aplicação por mês durante 6 meses, e Doxiciclina (100 mg), 10 mg/kg, 1 comprimido, duas vezes ao dia, por 30 dias. Em conclusão, microfilárias de D. immitis causaram lesões piogranulomatosas em tecido subcutâneo de um cão, relato anteriormente não descrito no Brasil.(AU)

Vector-borne pathogens of zoonotic concern in dogs from a Quilombola community in northeastern Brazil.

Canine vector-borne pathogens (CVBPs) comprise a group of disease agents mainly transmitted by ticks, fleas, mosquitoes and sand flies. In this study, we assessed the presence of CVBPs in an Afro-descendent community (Quilombola) of northeastern, Brazil. Dog blood samples (n = 201) were collected and analyzed by rapid test for the detection of antibodies against Leishmania spp., Anaplasma spp., Ehrlichia spp. and Borrelia burgdorferi sensu lato (s.l.), and antigens of Dirofilaria immitis. In addition, polymerase chain reactions were performed for Anaplasmataceae, Babesia spp., Hepatozoon spp., Rickettsia spp. and B. burgdorferi s.l. Overall, 66.7% of the dogs scored positive to at least one pathogen at serological and/or molecular methods. Antibodies against Ehrlichia spp. were the most frequently detected (57.2%; n = 115/201), followed by Anaplasma spp. (8.5%; n = 17/201), Leishmania spp. (8.5%; n = 17/201) and B. burgdorferi s.l. (0.5%; n = 1/201). For D. immitis, 11 out of 201 (5.5%) animals scored positive. At the molecular analysis, 10.4% (n = 21/201) of the samples scored positive for Babesia spp./Hepatozoon spp., followed by Anaplasmataceae (5.0%; n = 10/201) and Rickettsia spp. (3.0%; n = 6/201). All samples were negative for B. burgdorferi s.l. Our data demonstrated the presence of CVBPs in the studied population, with a high seropositivity for Ehrlichia spp. In addition, considering the detection of zoonotic pathogens in dogs and their relationship with people from Quilombola communities, effective control strategies are advocated for minimizing the risk of infection in this socially vulnerable human population and their pets.

A mixed-methods approach to understanding domestic dog health and disease transmission risk in an indigenous reserve in Guyana, South America.

Domestic dogs (Canis lupus familiaris) can transmit a variety of pathogens due to their ubiquitousness in urban, rural and natural environments, and their close interactions with wildlife and humans. In this study, we used a mixed-methods approach to assess the role of domestic dogs as potential intermediaries of disease transmission from wildlife to humans among indigenous Waiwai in the Konashen Community Owned Conservation Area, Guyana. To address these objectives we 1) performed physical examinations and collected biological samples to assess Waiwai domestic dog health, and 2) administered questionnaires to characterize the role of dogs in the community and identify potential transmission pathways between wildlife, dogs, and humans. We observed ectoparasites on all dogs (n = 20), including: fleas (100%), ticks (15%), botflies (30%), and jigger flea lesions (Tunga penetrans) (80%). Ten percent of dogs were seropositive for Ehrlichia canis/ewingii, 10% were positive for Dirofilaria immitis, and one dog was seropositive for Leishmania infantum. All dogs (n = 20) were seronegative for: canine distemper virus, Brucella canis, Leptospira serovars, Trypanosoma cruzi, Anaplasma phagocytophilum/platys and Borrelia burgdorferi. Our questionnaire data revealed that the Waiwai remove ectoparasites from their dogs, clean up dog feces, and administer traditional and/or Western medicine to their dogs. White blood cell, strongyle-type ova, and eosinophil counts were lower in dogs that were not frequently used for hunting, dogs that did receive traditional and/or western medicine, and dogs that were frequently kept in elevated dog houses, although differences were not statistically significant. While our results suggest that the Waiwai have developed cultural practices that may promote dog health and/or prevent zoonotic disease transmission, more research is necessary to determine the efficacy of these practices. Our study provides important data on the health of dogs and the potential for disease transmission to humans in a zoonotic hotspot.

Prevalence and risk factors for Dirofilaria immitis in dogs from Laguna, Santa Catarina, Brazil.

Dirofilaria immitis is a nematode found worldwide and able to infect several species, such as dogs, cats and, under rare circumstances, humans. In Brazil, most of the infections are related to coastal areas. The present study aimed at determining Dirofilaria immitis prevalence and evaluating the possible risk factors for infection in dogs, in Laguna, Santa Catarina, Brazil. Blood samples from 238 dogs were collected and a questionnaire was applied to the owners in order to obtain general information about the animals (age, gender, breed, coat color, home location (region), the use of dewormer/ectoparasiticide drugs, habits and behavior, roaming, insect control and the owner's knowledge about the disease). Samples were processed by blood smear techniques, modified Knott's test, immunochromatographic assay and PCR. Data were statistically analyzed by χ2 and OR. 4.62% was the overall prevalence of canine dirofilariasis and the suburb of Bananal, in Laguna, showed the highest prevalence (18.8%) when comparing with other regions (p < 0.05). However, there was no other significant factor related to the prevalence of D. immitis infection. Thus, the research have confirmed the presence of D. immitis in Laguna region, with a high prevalence in Bananal suburb, a dense forested area.

Filarids (Spirurida: Onchocercidae) in wild carnivores and domestic dogs from the Brazilian Atlantic forest.

Onchocercidae nematodes are heteroxenous parasites with worldwide distribution, and some of the species associated to animals may present zoonotic potential. Climatic changes and anthropic influences on the environment may result in vectors' proliferation, facilitating the spillover to humans and/or non-typical animal hosts. The Iguaçu National Park (PARNA Iguaçu), one of the most important Brazilian natural remanescents of Atlantic rainforest, is strongly affected by human activities such as tourism and agriculture. The complexity of this area is especially characterized by the close nexus between the rich wildlife, humans, and domestic animals, especially domestic dogs. Based on this, this research aimed to diagnose the Onchocercidae nematodes in wild carnivores and domestic dogs in the PARNA Iguaçu and the surrounding areas. For this, we collected 162 samples of seven species of wild carnivores and 225 samples of domestic dogs. The presence of microfilariae in the blood samples was diagnosed by the modified Knott's test and molecular screening, and the specific identification was based on sequencing of the myoHC and hsp70 genes. Microfilariae were detected only in ring-tailed coatis, in which we found five species: Mansonella sp. 1, Mansonela sp. 2, Onchocercidade gen. sp. 1, Onchocercidade gen. sp. 2, and Dirofilaria immitis. The morphological analysis supported the molecular findings. The domestic dogs were parasitized by Acanthocheilonema reconditum, representing a new locality record for this species. Phylogenetic analysis showed high genetic similarity among the four undetermined species and Mansonella spp., Brugia spp., and Wuchereria bancrofti. The presence of D. immitis in ring-tailed coatis may be result of spillover from dogs, even though the parasite was not diagnosed in the sampled dogs. The presence of several undetermined Onchocercidae species indicates the necessity of continuous investigations on wild and domestic animals from Neotropical area, especially considering the growing anthropic influence on forest remnants.

Parasitological, serological and molecular diagnosis of Dirofilaria immitis in dogs in Northeastern Brazil.

Dirofilaria immitis is a zoonotic filarid that mainly affects the domestic dog, causing a generally fatal chronic disease, known as heart worm disease. In addition to dogs, the parasite can affect wild canids, cats, and humans. Due to its importance to One Health, detection of parasitism by D. immitis in dogs can help the adoption of control measures that aim to reduce the occurrence of parasitosis in animals and humans. The detection of D. immitis is based on the use of parasitological, serological, and molecular methods, which vary in sensitivity and specificity. Therefore, the objective was to evaluate and compare the efficiency and performance of parasitological, serological, and molecular tests in the detection of D. immitis in dogs in Northeastern Brazil. Whole blood and serum from 140 dogs from the municipality of Sousa were used, varying between males and females; aged one to 17 years; pure and mixed breeds; domiciled and stray. Three microscopic parasitological techniques (MPT) were used: capillary blood smear (CBS), peripheral (PBS) and modified Knott test (MK) associated with the morphometric diagnosis of the microfilariae. For the detection of D. immitis antigens, a rapid immunochromatographic test (RIT) (ALERE Dirofilariose AG Teste kit®, Seogu-dong, Korea) was used, and polymerase chain reaction (PCR) as a molecular method. To evaluate the tests, PCR was considered the gold standard, and sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) values were calculated. To verify the agreement of the tests, the Kappa test was performed (p ≤ 0.05). From the 140 analyzed samples, 33.6% (48/140) presented microfilariae, antigen and/or parasitic DNA. 23.6% (33/140) were positive in the CBS; 25.7% (36/140) in the PBS; 29.3% (41/140) in the MK; 30% (42/140) in the RIT and 28.6% (40/140) in the PCR. All methods showed almost perfect agreement with PCR, high sensitivity (0.8-0.95), specificity (0.94-0.99), and values established with VPP (0.8571-0.9722) and VPN (0.9519-0.9797). The CBS and PBS showed less sensitivity and greater specificity. MK presented the highest sensitivity and RIT was the choice for hidden infections. Considering the occurrence of D. immitis in dogs in a non-coastal region of Northeastern Brazil, an epidemiological approach is recommended to identify risk factors for this zoonotic parasitosis.

Molecular characterization of canine filarioids in a previously non-endemic area of Rio de Janeiro State, Brazil.

Dirofilaria immitis is the causative agent of canine heartworm disease, a severe health problem in dogs, especially in coastal areas of tropical and subtropical regions of the world. We employed molecular methods to investigate the occurrence of canine infection by filarioids in five municipalities of Baixada Fluminense (Magé, Duque de Caxias, Guapimirim, Nova Iguaçu, and São João de Meriti), a non-endemic area of Rio de Janeiro State, Southeast Brazil. A total of 110 canine blood samples collected from 2017 to 2018 and positive for microfilariae at the modified Knott's test were screened by cPCR targeting DNA fragments of the 12S rDNA gene for filarial nematodes. Seventy-seven samples (70%) tested positive at the molecular analysis. Of these, 72 were identified as D. immitis and 5 (4.5%) as Acanthocheilonema reconditum. Dirofilaria repens was not detected in the studied municipalities of Baixada Fluminense. This is the first record of D. immitis and A. reconditum in the Baixada Fluminense region, Rio de Janeiro State, Brazil. The prevalence of D. immitis cases in the five municipalities suggests the establishment and maintenance of its enzootic cycle in the studied region, which indicate vulnerability to the occurrence of epidemic cycles and, possibly, human cases.