Frequency of Dirofilaria immitis infection in blood donor dogs of the Rio de Janeiro state.

Dirofilariasis, a parasitic disease caused by the nematode Dirofilaria immitis, commonly known as heartworm, primarily inhabits the pulmonary artery and right heart of dogs and other animals. The disease is transmitted through diptera, predominantly from the Culex, Aedes, and Anopheles genera. Dirofilariasis is cosmopolitan in nature, endemic in coastal regions and tropical climates. Factors such as temperature, humidity, vector density, and the presence of definitive hosts significantly contribute to the spread of this parasitic disease. In the state of Rio de Janeiro, a prevalence of 58.6% of D. immitis infected animals has been recorded in municipalities like Niterói. Given that blood transfusions are routine clinical procedures and blood bags are not always accurately evaluated, an investigation into D. immitis infection in blood donor dogs from the metropolitan region of Rio de Janeiro was conducted. A total of 1044 blood donor dog files from a blood bank in Niterói, RJ, collected from January 2019 to December 2022, were analyzed. These samples, originating from kennels in various municipalities in the Metropolitan Region, were tested for the presence of microfilariae through direct examination using tubes and microhematocrit evaluated in optical microscopy. Additionally, the search for antigens was conducted using the enzyme-linked immunosorbent assay technique. Out of the 1044 records evaluated, 17.8% (186/1044) were positive for heartworm infection, with 2% (21/1044) samples positive for microfilariae and 14.8% (154/1044) positive for D. immitis antigens. The high prevalence rate indicates that canine D. immitis infection remains prevalent in the state of Rio de Janeiro, necessitating effective guidelines for prescribing preventive medications by veterinarians and an increase in epidemiological surveillance in the region.

A dirofilariose é uma parasitose determinada pelo nematóide Dirofilaria immitis, que tem como habitat artéria pulmonar e coração direito de canídeos e outros animais, sendo por isso conhecido popularmente como verme do coração. A transmissão da parasitose ocorre por meio de dípteros principalmente dos gêneros Culex, Aedes e Anopheles. A dirofilariose é considerada cosmopolita, sendo endêmica em regiões litorâneas e de clima tropical. A temperatura, a umidade, a densidade de vetores e a presença de hospedeiros definitivos são considerados os principais fatores que contribuem para a propagação da parasitose. No estado do Rio de Janeiro, alguns municípios como Niterói, já foi registrada uma prevalência de 58.6% de animais infectados por D. immitis. Como as transfusões de sangue são procedimentos clínicos rotineiros e as bolsas de sangue nem sempre são avaliadas corretamente, decidiu-se investigar a infecção por D. immitis em cães doadores de sangue da região metropolitana do estado do Rio de Janeiro. Foram analisados 1044 prontuários de cães doadores de sangue de um banco de sangue localizado em Niterói, RJ, obtidos no período de janeiro de 2019 a dezembro de 2022. As amostras foram provenientes de canis localizados em diferentes municípios da Região Metropolitana, e testadas para presença de microfilárias por meio de exame direto utilizando-se tubos e microhematócrito avaliados em microscopia óptica e através da realização da pesquisa de antígenos utilizando-se a técnica de ELISA. Das 1044 fichas avaliadas, 17.8% (186/1044) das amostras foram positivas para infecção pelo verme do coração, sendo 2% (21/1044) positivas para presença de microfilárias e 14.75% (154/1044) positivas para presença de antígenos de D. immitis. A alta taxa de prevalência encontrada permite concluir que a infecção canina por D. immitis ainda apresenta alta prevalência no estado do Rio de Janeiro, exigindo orientações efetivas para a prescrição de medicamentos preventivos por médicos veterinários e aumento da vigilância epidemiológica na região.

Clinical and blood count findings in dogs naturally infected with Dirofilaria immitis.

Dirofilaria immitis is a nematode that infects canids worldwide as well as other mammalian species, including humans. Worms and dogs are well adapted to one another, making dogs the best urban host for the parasite. Nevertheless, 30% of dogs do not sufficiently present microfilaremia, that is, the low larval load impairs transmission by mosquitoes and diagnosis by its detection in the blood samples. Therefore, the canine diagnosis must always include a microfilaria test and serological tests to detect adult worm antigens. To describe the clinical findings in naturally infected dogs in Rio de Janeiro, 34 dogs were included in the study. All dogs were evaluated for history, anamnesis, physical examination, complete blood count (CBC), D. immitis testing for antigens (ELISA test SNAP 4Dx Plus®), and microfilarial burden. The most frequent complaint from the owners was coughing (14.7%, 5/34). The most common CBC finding was eosinophilia (29.4%), followed by thrombocytopenia (26.5%) and neutrophilia (14.7%). Of the 34 animals, 91.2% were microfilaremic, with a mean count of 11.939 microfilaria/mL. Veterinarians working in areas endemic to D. immitis should always undergo screening tests and pulmonary auscultation, and increased expiratory sounds, even in the absence of coughing, can be considered a sign of the disease, along with eosinophilia, thrombocytopenia, and neutrophilia.

Dirofilaria immitis, é um nematoide que infecta canídeos em todo o mundo, bem como outras espécies de mamíferos, incluindo humanos. Os vermes e os cães estão bem adaptados um ao outro, tornando os cães o melhor hospedeiro urbano para o parasita. Contudo, 30% dos cães não apresentam microfilaremia, prejudicando a transmissão pelos mosquitos e o diagnóstico por detecção de larvas em amostras de sangue. Portanto, o diagnóstico canino deve incluir sempre a pesquisa de microfilárias e sorologia para detecção do antígeno do verme adulto. Com o objetivo de descrever os achados clínicos de cães naturalmente infectados no Rio de Janeiro, 34 cães foram incluídos. Todos os cães foram avaliados por histórico, anamnese, exame físico, hemograma completo (CBC), teste de antígenos, pesquisa e contagem de microfilárias de D. immitis. A queixa mais frequente dos responsáveis foi a tosse (14,7% - 5/34). O achado de hemograma mais comum foi eosinofilia (29,4%), seguido de trombocitopenia (26,5%) e neutrofilia (14,7%). Dos 34 animais, 91,2% eram microfilarêmicos com contagem média de 11.939 microfilárias/mL. Os veterinários que atuam em áreas endêmicas de D. immitis devem sempre realizar exames de triagem e ausculta pulmonar, pois mesmo na ausência de tosse, sons expiratórios aumentados podem ser considerados um sinal da doença, assim como eosinofilia, trombocitopenia e neutrofilia.

Intra-abdominal transmissible venereal tumor in a dog: a case report.

Transmissible venereal tumor (TVT) is a malignant round cell neoplasm that primarily affects the genital region of dogs. Despite being sexually transmitted, transmission can occur through contact with mucous membranes and cutaneous tissue. Although less routine, TVT has been described in several extragenital regions, such as the nasal plane, oral cavity, eyeball, eyelid, and anus. Although metastases are infrequent, they can occur in the skin, inguinal lymph nodes, liver, kidneys, spleen, intestine, heart, brain, lungs, and other organs. The clinical signs of TVT are usually related to serosanguineous secretion, intense odor, deformity, ulceration, and possibly areas of necrosis. In cases of metastases, clinical signs will depend on the affected organ. The treatment of choice for TVT is chemotherapy with vincristine. The present study aimed to report the case of a 2-year-old mixed-breed canine with intra-abdominal nodules detected by ultrasound examination, which were later diagnosed as a TVT by histopathology and immunohistochemistry.

O tumor venéreo transmissível (TVT) é uma neoplasia maligna de células redondas que acomete principalmente a região genital de cães. Apesar de ser sexualmente transmissível, a transmissão pode ocorrer através do contato com mucosas e tecidos da pele. Embora menos rotineiro, o TVT tem sido descrito em diversas regiões extragenitais, como plano nasal, cavidade oral, globo ocular, pálpebra e ânus. Embora as metástases sejam infrequentes, elas podem ocorrer na pele, linfonodos inguinais, fígado, rins, baço, intestino, coração, cérebro, pulmão e outros órgãos. Os sinais clínicos do TVT geralmente estão relacionados à secreção serossanguinolenta, odor intenso, deformidade, ulceração, podendo ou não haver áreas de necrose e, nos casos de metástases, os sinais clínicos vão depender do órgão acometido. O tratamento de escolha para TVT é a quimioterapia, com uso de vincristina. O presente trabalho tem como objetivo relatar o caso de um canino de dois anos de idade, sem raça definida, com nódulos intra-abdominais detectados ao exame ultrassonográfico, que posteriormente foram diagnosticados como tumor venéreo transmissível por meio de histopatologia e imunohistoquímica.

Pulmonary atelectasis in a young dog with Cor pulmonale: clinical and radiographic follow-up.

Pulmonary atelectasis is a disease characterized by the collapse of the pulmonary alveoli, leading to partial or total loss of function in the affected lung, and is mostly described in older dogs. It occurs due to chronic inflammatory and obstructive processes such as pneumonia. In infants who do not feed directly from the mother, it is common to develop aspiration pneumonia due to inhalation of a milk replacer. Once aspirated, food generates an inflammatory process in the airway that alters the function of the pulmonary surfactant, increases mucus production, and causes consequent airway obstruction, which may progress to alveolar and bronchial collapse. The aim of the present study was to report a case of a 4-month-old canine with pulmonary atelectasis secondary to bronchopneumonia and the outcome of the clinical case. The patient presented with cough, exercise intolerance, tachypnea, and progressive weight loss. Thoracic radiographic examination was performed to identify displacement of the mediastinum and heart overlapping the collapsed lung, interstitial-alveolar pattern associated with atelectasis of the middle lobe of the right lung, and a diffuse interstitial bronchial pattern throughout the other lung fields. Pulmonary support treatment was administered with antibiotics, bronchodilators, mucolytics, and inhaled corticosteroids, with resolution of clinical and radiographic symptoms after 60 days of treatment. Therefore, adequate treatment of chronic bronchopneumonia is effective in resolving pulmonary atelectasis and its associated clinical complications.

A atelectasia pulmonar é uma enfermidade caracterizada pelo colapso dos alvéolos pulmonares levando a perda de função parcial ou total do pulmão acometido, sendo mais frequente em cães mais velhos. Ocorre devido a processos inflamatórios crônicos e obstrutivos como as pneumonias. Em filhotes que não se alimentam diretamente da mãe, é comum o desenvolvimento de pneumonia aspirativa devido à inalação de fórmula de leite. Uma vez broncoaspirado, o alimento gera um processo inflamatório que altera a função do surfactante pulmonar, aumento na produção de muco e consequente obstrução das vias aéreas, podendo progredir para colapso de alvéolos e brônquios. O objetivo do presente estudo foi relatar um caso de um canino, de 4 meses de idade, com atelectasia pulmonar secundária a broncopneumonia e a evolução do caso clínico. O paciente apresentava sinais de tosse, intolerância a exercícios, taquipneia e emagrecimento progressivo. Realizado exame radiográfico de tórax, identificou-se deslocamento de coração sobrepondo-se ao pulmão colapsado, padrão interstício-alveolar associado a atelectasia do lobo médio do pulmão direito, além de padrão intersticial brônquico difuso pelos demais campos pulmonares. O tratamento de suporte pulmonar foi realizado com antibióticos, broncodilatadores, mucolíticos e corticosteroides inalatórios, com resolução dos sintomas clínicos e radiográficos após 60 dias de tratamento. Portanto, o tratamento adequado para broncopneumonia crônica foi eficaz na resolução da atelectasia pulmonar e suas complicações clínicas.

Feline Heartworm in Clinical Settings in a High Canine Prevalence Area.

Heartworm (HTW) infection in cats is associated with persistent pulmonary pathology, even when clinical signs are absent. Treatment options for cats are limited once infected, making prevention an important topic for discussion with cat owners. In Brazil, tests to detect feline HTW infections are unavailable, likely leading to an underestimation of its impact on the wellbeing of cats. The present study investigated the seroprevalence of HTW antigen in cats living in an area with high canine HTW prevalence and investigated risk factors and clinical signs associated with HTW disease in cats from Rio de Janeiro, Brazil. Clinical examinations were conducted, and serological evaluations performed with a point-of-care test (SNAP® Feline Triple® Test, IDEXX Laboratories, Inc.). A total of 586 cats were examined. The HTW antigen seroprevalence was 1.2%. Heartworm positive results were significantly associated with vomiting and abnormal lung sounds. Results from this study indicate that cats residing in areas of high canine HTW prevalence should have HTW disease as a differential diagnosis when presenting with compatible clinical signs. Veterinarians should prioritize client education and promote regular use of effective prophylaxis to protect feline health.

Disfunção miocárdica secundária a sepse em cão: relato de caso / Myocardial dysfunction secondary to sepsis in dog: case report

A redução do empenho do miocárdio é um achado frequente em casos de sepse ou choque séptico, sendo a piometra uma das principais causas de sepse em cães. No presente trabalho relata-se um caso de sepse secundária à piometra levando à disfunção miocárdica em um canino, fêmea, da raça White West Highland Terrier, de dez anos de idade com histórico de prostração e hiporexia. Ao exame físico foi observada presença de secreção vulvar purulenta, abdômen abaulado e tenso à palpação. Foram realizados exames complementares, incluindo hemograma com resultado compatível com quadro infeccioso, bioquímica revelando hipocalemia e hipocalcemia, e exames de imagem. Observou-se por meio do exame ultrassonográfico presença de grande quantidade de líquido com celularidade em cornos e corpo uterino, compatível com piometra. Alterações compatíveis com sepse foram observadas durante o atendimento e estabilização do animal. No exame ecocardiográfico foi observado aumento dos diâmetros sistólico e diastólico do ventrículo esquerdo com diminuição da fração de encurtamento e ejeção, compatível com disfunção sistólica do ventrículo esquerdo. A referida paciente recebeu alta médica após correção cirúrgica e estabilização dos parâmetros clínicos, incluindo a disfunção sistólica, sendo relatado óbito sete dias após. Sugere-se que a causa mortis tenha sido a disfunção sistólica causada pela sepse. Conclui-se

The reduction of myocardial commitment is a frequent finding in cases of sepsis or septic shock, and piometra is one of the main causes of sepsis in dogs. In the present study, the case of sepsis secondary to piometra is reported leading to myocardial dysfunction in a canine, female, of the 10-year-old White West Highland Terrier with a history of prostration and hyporexia. On physical examination, the presence of purulent vulvar secretion, bulging abdomen and taut palpation was observed. Complementary tests were performed, including blood count, biochemistry and imaging tests. It was observed through ultrasound examination the presence of a large amount of fluid with cellularity in horns and uterine body, compatible with piometra. Alterations compatible with sepsis were observed during the care and stabilization of the animal. On echocardiographic examination, an increase in systolic and diastolic diameters of the left ventricle was observed with decreased shortening and ejection fraction, compatible with systolic dysfunction of the left ventricle. The patient received medical discharge after surgical correction and stabilization of clinical parameters, and died seven days later. It is suggested that the cause of death was systolic dysfunction caused by sepsis. It is concluded that myocardial dysfunction is a prognostic determinant factor in cases of sepsis, emphasizing the importance of its diagnosis and early treatment.

Disfunção miocárdica secundária a sepse em cão: relato de caso / Myocardial dysfunction secondary to sepsis in dog: case report

A redução do empenho do miocárdio é um achado frequente em casos de sepse ou choque séptico, sendo a piometra uma das principais causas de sepse em cães. No presente trabalho relata-se um caso de sepse secundária à piometra levando à disfunção miocárdica em um canino, fêmea, da raça White West Highland Terrier, de dez anos de idade com histórico de prostração e hiporexia. Ao exame físico foi observada presença de secreção vulvar purulenta, abdômen abaulado e tenso à palpação. Foram realizados exames complementares, incluindo hemograma com resultado compatível com quadro infeccioso, bioquímica revelando hipocalemia e hipocalcemia, e exames de imagem. Observou-se por meio do exame ultrassonográfico presença de grande quantidade de líquido com celularidade em cornos e corpo uterino, compatível com piometra. Alterações compatíveis com sepse foram observadas durante o atendimento e estabilização do animal. No exame ecocardiográfico foi observado aumento dos diâmetros sistólico e diastólico do ventrículo esquerdo com diminuição da fração de encurtamento e ejeção, compatível com disfunção sistólica do ventrículo esquerdo. A referida paciente recebeu alta médica após correção cirúrgica e estabilização dos parâmetros clínicos, incluindo a disfunção sistólica, sendo relatado óbito sete dias após. Sugere-se que a causa mortis tenha sido a disfunção sistólica causada pela sepse. Conclui-se que a disfunção miocárdica é um fator determinante de prognóstico em casos de sepse, o que ressalta a importância de seu diagnóstico e tratamento precoce.

The reduction of myocardial commitment is a frequent finding in cases of sepsis or septic shock, and piometra is one of the main causes of sepsis in dogs. In the present study, the case of sepsis secondary to piometra is reported leading to myocardial dysfunction in a canine, female, of the 10-year-old White West Highland Terrier with a history of prostration and hyporexia. On physical examination, the presence of purulent vulvar secretion, bulging abdomen and taut palpation was observed. Complementary tests were performed, including blood count, biochemistry and imaging tests. It was observed through ultrasound examination the presence of a large amount of fluid with cellularity in horns and uterine body, compatible with piometra. Alterations compatible with sepsis were observed during the care and stabilization of the animal. On echocardiographic examination, an increase in systolic and diastolic diameters of the left ventricle was observed with decreased shortening and ejection fraction, compatible with systolic dysfunction of the left ventricle. The patient received medical discharge after surgical correction and stabilization of clinical parameters, and died seven days later. It is suggested that the cause of death was systolic dysfunction caused by sepsis. It is concluded that myocardial dysfunction is a prognostic determinant factor in cases of sepsis, emphasizing the importance of its diagnosis and early treatment.

Mosquito abundance in a Dirofilaria immitis hotspot in the eastern state of Rio de Janeiro, Brazil.

Coastal lowlands in the state of Rio de Janeiro, Brazil, support high numbers of heartworm-infected dogs. Microfilariae of heartworm need to be ingested by a potencial mosquito vector in order to develop into infective larvae and infect a new host. Ochlerotatus taeniorhynchus and Ochlerotatus scapularis are the primary vector species in the coastal lowlands of metropolitan Rio de Janeiro; thus, the aim of this study was to investigate whether these two species were abundant enough at the heartworm hotspot in the eastern area of the state to be important to the local parasite's life cycle. The study was conducted at the Massambaba sandbank (22°55'45″S;42°18'51″W), where canine heartworm prevalence was 53.1%. Mosquitoes were captured monthly using two traps with CO2, as well as eventual human landing. A total of 6118 mosquitoes of 16 species were collected. Ochlerotatus taeniorhynchus (37.5%), Culex quinquefasciatus (19.3%), Oc. scapularis (18.2%), and Coquillettidia sp. (10.5%) were the most abundant species. The monthly variation in frequency was marked for Oc. scapularis and Cx. quinquefasciatus and steadier for Oc. taeniorhynchus and Coquillettidia sp. The abundance of the two Ochlerotatus species reaffirms that they are the primary natural vectors for D. immitis in the coastal Rio de Janeiro state lowlands.

Heat pretreatment of canine samples to evaluate efficacy of imidacloprid + moxidectin and doxycycline in heartworm treatment.

BACKGROUND: Considering the recent information on the increase of Dirofilaria immitis antigen detection by rapid assays in canine blood samples after heat treatment, the proposal that immune complexes block D. immitis antigen detection and that macrocyclic lactone + doxycycline (alternative protocol) might lead to increased production of those immune complexes, resulting in the erroneous diagnosis of adult worm elimination, and that there is no recommended adulticide marketed in Brazil, a study was performed to evaluate the interference of moxidectin + doxycycline (moxi-doxy) on diagnostic procedures when heartworm positive dogs are treated with this alternative protocol. Twenty-two naturally infected pet dogs were treated monthly with topical 10% imidacloprid + 2.5% moxidectin and with oral doxycycline (10 mg/kg BID/30 days) (moxi-doxy). All the dogs had their microfilaremia level determined prior to the first day of treatment, and were tested every 6 months for microfilariae (Mf) detection prior to heating, and for antigen detection prior to and after heating, the sample. RESULTS: The results indicate that the treatment protocol can eliminate adult heartworms as early as 6 months after the first dose, especially in low microfilaremic dogs (< 300 Mf/ml). In this study, all dogs were free of heartworm antigen after 18-24 months of treatment. In a comparison of pre-heated samples and non-heated samples, sample pre-heating increased antigen detection sensitivity, and non-heated samples tended to be antigen-negative earlier than the pre-heated samples, especially when dogs had low microfilaremia levels. These discrepancies were not present in a subsequent sample of the same dog 6 months later. CONCLUSIONS: Two negative antigen test results 6 months apart can be recommended as the criterion to consider when a dog has been cleared of infection. The initial microfilaremia level of a dog can be used to estimate the necessary time frame to end the treatment period.

Update on Dirofilaria immitis epidemiology in South America and Mexico: literature review / Atualização sobre a epidemiologia de Dirofilaria immitis na América do Sul e no México: revisão de literatura

Dirofilaria immitis (Leidy, 1856; Raillet & Henry 1911) is a parasite that is widely disseminated around the globe, with a higher prevalence in warm, humid climates. The first report of its occurrence in South America is from 1878 in Brazil. At that time, reports were scarce and difficult to retrieve ­ therefore, gathering them will facilitate record-keeping over time. Four databases were searched (Scopus, MEDLINE, LILACS, and PubMed) and the search keywords were "Dirofilaria" or "heartworm" and the countries' names. Four countries lacked reports (Bolivia, Ecuador, French Guiana, and Uruguay) and other three (Suriname, Guyana, and Paraguay) had only old reports. Chile was the only country in which studies were conducted over time, and no infected dogs were registered. For the other six countries (Mexico, Peru, Colombia, Venezuela, Argentina, and Brazil), reports showed that the infection frequency varied over time and with the surveyed area. Therefore, the information indicates that D. immitis is established, and veterinarians must institute preventive programs to optimally care for their patients and protect the health of their families.(AU)

Dirofilaria immitis é um nematoide de ampla distribuição geográfica, que ocorre com maior frequência em áreas quentes e úmidas do planeta. O primeiro registro de sua ocorrência na América do Sul foi realizado em 1878, no Brasil. Naquela época os registros eram poucos e raramente de fácil obtenção, razão pela qual reuni-los facilitará a recuperação da memória ao longo dos anos. Quatro bases de dados (Scopus, MEDLINE, LILACS e PubMed) foram estudadas utilizando-se as palavras-chave "Dirofilaria" ou "heartworm", os nomes dos países da América do Sul e o México. Nenhum registro foi encontrado para quatro países (Bolívia, Equador, Guiana Francesa e Uruguai) e para outros três (Suriname, Guiana e Paraguai) os registros eram antigos. Apenas o Chile é o território onde houve estudos registrados com ausência do parasita. Os outros países (México, Peru, Colômbia, Venezuela, Argentina e Brasil) apresentam registros com frequência variável no tempo ou no espaço. Assim, as informações reunidas indicam que infecções por D. immitis ocorrem na maior parte da América do Sul e no México e que os médicos veterinários devem instituir programas preventivos para garantir cuidados médicos de qualidade aos pacientes e para proteger a saúde destes e de suas famílias.(AU)

Effects of doxycycline on the endosymbiont Wolbachia in Dirofilaria immitis (Leidy, 1856)--naturally infected dogs.

Dirofilaria immitis carries intracellular endosymbiotic bacteria of the genus Wolbachia, known to be vital for the worms and sensitive to tetracycline antibiotics. With the purpose of studying the interaction between D. immitis and the endosymbiont Wolbachia sp., heartworm naturally infected microfilaremic or antigenemic dogs were treated with doxycycline (10mg/kg/day of the drug in three cycles of 21 days each, with 6-month intervals). Blood samples were collected on days 0, 7 and 21 of each treatment as well as on day 111 after the beginning of each cycle. A final sample was collected on day 723 from the beginning of the first treatment. The samples were examined for the presence and number of microfilariae and the presence of antigen as well as the presences of D. immitis and Wolbachia sp. DNA using PCR (polymerase chain reaction). With this approach, an evaluation of the effect of doxycycline on antigenemia and on the presence of Wolbachia sp. DNA in dogs with heartworm infection was possible. Doxycycline treatment did not alter the detection of adult parasite antigens with the exception of two animals, though the number of animals carrying Wolbachia sp. DNA decreased, despite the presence of the microfilariae. The effect of the antibiotic therapy on the worms may have interfered with the transmission of heartworm disease because the population of microfilariae and the number of microfilaremic dogs were reduced and the microfilariae positive samples that were found did not test positive for Wolbachia sp. in many cases. These findings suggest that in areas were doxycycline is extensively used D. immitis transmission may be impaired by the reduction on the number of microfilariae and on the endosymbiotic bacteria in the larvae turning them incapable of completing development once they infected a new host.

Detection of Wolbachia DNA in blood from dogs infected with Dirofilaria immitis.

Dirofilaria immitis is the causative agent of heartworm disease in canines and felines, and pulmonary dirofilariasis in man. It harbors a symbiotic intracellular bacterium from the genus Wolbachia that plays an important role in its biology and contributes to the inflammatory pathology of the heartworm. This endosymbiont is sensitive to the tetracycline family of antibiotics prompting its use in the treatment of filariasis. To track Wolbachia during treatment, primers were designed based on the FtsZ gene from Wolbachia. These primers amplify a single PCR product with the expected size from DNA samples derived from various species of worms that harbor Wolbachia (D. immitis, Brugia malayi and Brugia pahangy). The detection limit of Wolbachia DNA in the assay was 80 pg of D. immitis DNA. Furthermore, the primer set successfully amplified the expected PCR product using blood samples from dogs harboring the heartworm and circulating microfilariae.

Attraction of mosquitoes to domestic cats in a heartworm enzootic region.

Heartworm disease is caused by a mosquito-borne parasite that can affect many different mammalian species and has worldwide distribution. The agent, Dirofilaria immitis (Leidy 1856), infect mainly dogs but feline infection have been frequently reported in the last decade. Feline heartworm infection is difficult to detect, therefore, low reported prevalence could reflect true low prevalence or poor diagnostic efficiency. As mosquitoes are known to be attracted differently by different mammalian species, mosquitoes were collected from both a cattery and a contiguous home located in a canine heartworm enzootic area in Niterói, state of Rio de Janeiro, Brazil. For 14 months, mosquitoes were collected weekly for genus identification, speciation when possible, and for individual blood meal identification. Culex species mosquitoes were the most captured and those most frequently found with feline blood meal, followed by Aedes species that, although captured in lower numbers, also fed on feline blood. While Culex species mosquitoes have been reported as potential secondary heartworm vectors for dogs and primary vectors for cats, the present results suggest that Aedes species mosquitoes may also be involved in feline heartworm transmission in a larger proportion than previously thought.