Whole genome amplification and sequencing of individual Dirofilaria immitis microfilariae.

Dirofilaria immitis is a filarial parasitic nematode of veterinary significance. With the emergence of drug-resistant isolates in the USA, it is imperative to determine the likelihood of resistance occurring in other regions of the world. One approach is to conduct population genetic studies across an extensive geographical range, and to sequence the genomes of individual worms to understand genome-wide genetic variation associated with resistance. The immature life stages of D. immitis found in the host blood are more accessible and less invasive to sample compared to extracting adult stages from the host heart. To assess the use of immature life stages for population genetic analyses, we have performed whole genome amplification and whole-genome sequencing on nine (n = 9) individual D. immitis microfilaria samples isolated from dog blood. On average, less than 1% of mapped reads aligned to each D. immitis genome (nuclear, mitochondrial, and Wolbachia endosymbiont). For the dog genome, an average of over 99% of mapped reads aligned to the nuclear genome and less than 1% aligned to the mitochondrial genome. The average coverage for all D. immitis genomes and the dog nuclear genome was less than 1, while the dog mitochondrial genome had an average coverage of 2.87. The overwhelming proportion of sequencing reads mapping to the dog host genome can be attributed to residual dog blood cells in the microfilariae samples. These results demonstrate the challenges of conducting genome-wide studies on individual immature parasite life stages, particularly in the presence of extraneous host DNA.

Microfilaruria of Dirofilaria immitis in a dog from Italy.

Dirofilaria immitis is a mosquito-borne nematode-causing canine heartworm disease, with adult worms localized in the pulmonary arteries and right heart. In rare cases, ectopic migration might occur, and adults and blood circulating microfilariae can be found in unusual organs or fluids (e.g., eyes, abdominal cavity, bone marrow, and urine). A 17-year-old mixed-breed female dog was presented in a private veterinary clinic in Italy for hematuria and dysuria. Physical examination showed cardiac mitral murmur with marked respiratory distress and cyanotic mucous membranes after handling. Abdominal ultrasounds revealed a non-specific chronic cystopathy, while the echocardiography showed enlargement of the right heart associated with tricuspid insufficiency and mitral regurgitation, with the presence of an adult filariae in the right ventricular chamber. Circulating microfilariae were observed in the blood smear and molecularly identified as D. immitis. Unusual microfilaruria was detected in the urine sediment. Data presented raise awareness about the occurrence of microfilariae in unusual locations, such as the bladder, suggesting the need of a thorough clinical and laboratory assessment where D. immitis is endemic.

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.

Emerging human pulmonary dirofilariasis in Hungary: a single center experience.

BACKGROUND: Human pulmonary dirofilariasis (HPD) is rare in Hungary, and it stems from Dirofilaria immitis, mainly transmitted through mosquito bites, with dogs as primary hosts. Despite its prevalence in veterinary settings, human cases are infrequent. Historically, Mediterranean countries report most HPD cases, but sporadic cases occur in temperate European regions. Radiologically, HPD often manifests in a non-specific manner, resembling pulmonary neoplasms, leading to unnecessary surgery and patient distress. METHODS: This study presents a notable case series from Hungary, encompassing a 12-year period, documenting 5 instances of HPD with the aim to provide baseline estimate of occurrence for future comparison. RESULTS: Among the patients studied, all were of middle age (median: 52 years, range: 37-69) and exhibited tumor-like lesions, primarily localized to the right lung, necessitating lobectomy or wedge resection. Histological examination consistently revealed a necrotizing granulomatous response characterized by remnants of helminths, without the presence of ovules. Furthermore, rigorous diagnostic procedures excluded other potential infectious agents through specialized staining techniques. Polymerase chain reaction analysis definitively confirmed the diagnosis of HPD in each case. CONCLUSIONS: This case series highlights HPD as a seldom zoonosis, with a probable escalation in its occurrence within temperate regions. Therefore, clinicians should maintain a heightened awareness of HPD in the differential diagnosis of pulmonary coin lesions. Early recognition and diagnosis are paramount for appropriate management and prevention of potential complications associated with this increasingly recognized infectious entity.

Can nematode infection cause internal bleeding in dogs? A case of Dirofilaria immitis infection in cavitary fluids.

A 9-year-old dog was presented with weight loss, respiratory effort, and an enlarged abdomen. Imaging studies and exploratory surgery showed pulmonary and splenic masses and bi-cavitary effusion, later classified as hemorrhage. Cytology of the peritoneal and pleural fluids also revealed several microfilariae. Immunologic and molecular analyses confirmed Dirofilaria immitis infection and histopathology of the spleen indicated a cavernous endothelial proliferation with undefined etiology (hemangiosarcoma vs reaction to parasite infestation). The nematode larvae are speculated to have entered body cavities via erratic migration or via hemorrhage and visceral lesions to be related to parasitism. Nematode infection should be considered as a differential diagnosis for internal bleeding of undetermined origin.

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.

Evaluation of diagnostic techniques for early detection of heartworm in experimentally infected dogs: identification of Dirofilaria immitis-derived microRNA in the initial 28 weeks post-inoculation.

BACKGROUND: Dirofilaria immitis, commonly known as heartworm (HW), is a parasitic nematode transmitted by various mosquito species, leading to heartworm disease (HWD) in dogs. Diagnosis of HW typically involves antigen or microfilariae detection, or visualization of adult worms through imaging or post mortem examination. Polymerase chain reaction (PCR) and micro RNA (miRNA) detection have been explored for HW diagnosis. METHODS: Three dogs, previously experimentally infected with HW, underwent blood sampling every 4 weeks for 7 months. Samples were assessed for antigen presence after heat treatment, PCR amplification, and microfilaria examination using Giemsa-stained thick smears. Additionally, whole blood aliquots underwent miRNA deep sequencing and bioinformatic analysis. RESULTS: Heartworm antigen was detectable after heat treatment at 20 weeks post-inoculation and via PCR at 24 weeks, with microfilariae observed in peripheral blood smears at 28 weeks. However, deep miRNA sequencing revealed that the miRNA candidate sequences are not consistently expressed before 28 weeks of infection. CONCLUSIONS: While ancillary molecular methods such as PCR and miRNA sequencing may be less effective than antigen detection for detecting immature larval stages in an early stage of infection, our experimental findings demonstrate that circulating miRNAs can still be detected in 28 weeks post-infection.

Detection of Dirofilaria immitis using microscopic, serological and molecular techniques among dogs in Cabo Frio, RJ, Brazil / Detecção de Dirofilaria immitis utilizando técnicas microscópicas, imunológicas e moleculares em cães de Cabo Frio, RJ

Abstract Heartworm disease is a health problem for dogs and cats, especially in tropical and subtropical coastal regions of the world. Some studies have compared the efficacy of the diagnostic techniques used to detect this parasitosis. Therefore, the aim of this study was to compare parasitological optical microscopy (POM), serological and molecular techniques for diagnosing canine heartworm infection. Samples were collected between July 2015 and April 2016 from 103 dogs in Cabo Frio, RJ, Brazil. The wet fresh blood, thick smears, thin smears and modified Knott's test were used to detect microfilariae. ELISA (Snap™ 4Dx ® IDEXX) was used to detect antigens and the polymerase chain reaction (PCR) was used to detect DNA and enable sequencing for species differentiation and confirmation. 19.4% of samples were positive according to microscopy. Through PCR, 15.5% of the total were positive. Using ELISA, the positivity rate was 29.1%. Occult heartworm infection was detected in 11.6% of the samples. ELISA sensitivity was shown to be higher than PCR or microscopy (P = 0.001). Sequencing of samples confirmed the presence of Dirofilaria immitis and Acanthocheilonema reconditum . ELISA was more effective for serological diagnosis canine heartworm and should be used in clinical and epidemiological studies.

Resumo A dirofilariose é um problema de saúde para cães e gatos, especialmente nas regiões costeiras tropicais e subtropicais do mundo. Alguns estudos compararam a eficácia das técnicas de diagnóstico usadas para detectar esta parasitose. Portanto, o objetivo deste estudo foi comparar a microscopia óptica (OM), técnicas sorológicas e moleculares para o diagnóstico de infecção por Dirofilaria immitis . Foram coletadas, entre julho de 2015 e abril de 2016, amostras de 103 cães em Cabo Frio, RJ, Brasil. O exame direto, distensão espessa, distensão delgada e o teste de Knott modificado foram usados para detectar microfilárias. O ELISA (Snap ™ 4Dx ® IDEXX) foi usado para detectar antígenos e a reação em cadeia da polimerase (PCR) foi usada para detectar DNA e o sequenciamento para diferenciação e confirmação de espécie. Das amostras, 19,4% foram positivas de acordo com a microscopia. Por PCR, 15,5% do total foram positivos. Utilizando o ELISA, a taxa de positividade foi de 29,1%. Dirofilariose oculta foi detectada em 11,6% das amostras. A sensibilidade ao ELISA mostrou-se superior à PCR ou microscopia (P = 0,001). O sequenciamento das amostras confirmou a presença de Dirofilaria immitis e Acanthocheilonema reconditum . O ELISA foi mais eficaz no diagnóstico sorológico de dirofilariose canina e deve ser usado em estudos clínicos e epidemiológicos.

Dirofilaria immitis infection in dogs in Algodoal Island, Brazilian Amazon / Infecção por Dirofilaria immitis em cães na Ilha de Algodoal, Amazônia brasileira

Dirofilaria immitis, a parasite that mainly infects domestic or wild canids, but can infect felines or humans as well, is frequent in many Brazilian areas. The main objective of this research was to determine the prevalence of natural canine infection at the Algodoal-Maiandeua Island complex, in the coastal region of the state of Pará, Brazil. A total of 67 dogs were sampled for blood microfilariae detection and for D. immitis DNA detection. Microfilaria and D. immitis DNA could be detected in 35.8% (24/67) of the animals. In one dog's sample no microfilariae were detected, but the PCR was positive, suggesting that either larvae recently were eliminated or adults died shortly before sample collecting. Therefore, it can be concluded that the occurrence of D. immitis is a health threat for domestic and wild canids at the Island of Algodoal, as well as for feline or human health.(AU)

Dirofilaria immitis, um parasito que infecta principalmente canídeos domésticos ou selvagens, embora também possa infectar felinos e humanos, é frequente em muitas áreas do Brasil. O objetivo deste estudo foi determinar a ocorrência da infecção natural em cães provenientes do complexo da Ilha de Algodoal-Maiandeua, região litorânea do estado do Pará, Brasil. Um total de 67 cães tiveram o sangue coletado para detecção de microfilárias de D. immitis e seu DNA. Microfilárias e o DNA de D. immitis foram detectados em 35,8% (24/67) dos animais. Na amostra de um animal, não foram observadas microfilárias, mas o seu DNA foi detectado, sugerindo que as larvas tenham sido recentemente eliminadas ou os adultos tenham morrido antes da coleta da amostra. Portanto, pode-se concluir que a ocorrência de D. immitis é uma ameaça à saúde de canídeos domésticos no complexo da Ilha de Algodoal-Maiandeua, bem como para felinos e seres humanos.(AU)

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)

Heartworm (Dirofilaria immitis) disease in a Brazilian oncilla (Leopardus tigrinus) / Doença do Verme do Coração (Dirofilaria immitis) em gato-do-mato-pequeno (Leopardus tigrinus) no Brasil

Heartworm disease is caused by the intravascular nematode Dirofilaria immitis, a pathogen of public health importance usually associated to domestic dogs and cats, and to a lesser extend to other mammal species. The oncilla (Leopardus tigrinus) is a threatened neotropic felid species that naturally occurs in Brazil. Here, we report the encounter of adult and larval stages of heartworms in a female specimen of L. tigrinus, probable of free-ranging origin, from Ubatuba, São Paulo, Brazil, which died showing clinical signals compatible with heartworm disease. This was the first reported case of D. immitis infection and associated disease in L. tigrinus, also suggesting that the oncilla acted as a definitive host for this parasite. The present findings confirmed D. immitis as a pathogenic agent for this felid species, thus supporting the recommendation for the inclusion of diagnostic testing for this pathogen in routine health screening procedures for captive and free-ranging oncillas in Brazil, especially in those localities where climate conditions support the occurrence of the parasite. Potential reservoirs as oncillas are established beyond the reach of veterinary care, thus representing a continuing risk for domestic animals and humans acquiring heartworm infection. We encourage further serologic and molecular studies aiming to establish D. immitis prevalences in L. tigrinus and other wild carnivores in the region of Ubatuba, as well as ecological and veterinary studies to access the role of this pathogen for the survival of this threatened felid species.

A doença do verme do coração é causada pelo nematódeo intravascular Dirofilaria immitis, um patógeno de importância em Saúde Pública geralmente associado a cães e gatos domésticos e, em menor extensão, a outras espécies de mamíferos. O gato-do-mato-pequeno (Leopardus tigrinus) é uma espécie ameaçada de felídeo neotropical que ocorre naturalmente no Brasil. Aqui relatamos o encontro de estágios adultos e larvais de vermes do coração em uma fêmea de L. tigrinus, provavelmente de vida livre e originária de Ubatuba, São Paulo, Brasil, que veio a óbito demonstrando sinais clínicos compatíveis desta doença. Este é o primeiro caso relatado de infecção e doença associada com D. immitis em L. tigrinus, sugerindo também que o gato-do-mato-pequeno agiu como hospedeiro definitivo para este parasita. Estes achados confirmaram que D. immitis é um agente patogênico para esta espécie de felino, sugerindo a recomendação para a inclusão de testes diagnósticos para este patógeno em procedimentos rotineiros de avaliação da saúde para gatos-do-mato-pequenos mantidos em cativeiro e de vida livre no Brasil, especialmente em localidades onde as condições climáticas permitam a ocorrência do parasita. Os gatos-do-mato-pequenos são potenciais reservatórios da D. immitis, mas vivem fora do alcance veterinário, representando desta forma um risco contínuo para animais domésticos e humanos. Encorajamos a realização de outros estudos epidemiológicos a fim de estabelecer as prevalências de infecção por D. immitis em L. tigrinus e outros carnívoros selvagens na região de Ubatuba, assim como estudos ecológicos e médicos veterinários para se acessar o papel deste patógeno para a sobrevivência desta espécie ameaçada de felídeo.

Vector competence of Culex quinquefasciatus Say, 1823 exposed to different densities of microfilariae of Dirofilaria immitis (Leidy, 1856) / Competência vetorial de Culex quinquefasciatus Say, 1823 exposto a diferentes densidades de microfilárias de Dirofilaria immitis (Leidy, 1856)

The metropolitan region of Recife, Brazil is endemic for Dirofilaria immitis and has an environment favorable to the development of Culex quinquefasciatus. The goal of this study was to evaluate the vector competence of the Cx. quinquefasciatus RECIFE population for D. immitis transmission. A total of 2,104 females of Cx. quinquefasciatus RECIFE population were exposed to different densities of D. immitis microfilariae blood meals, ranging from 1,820 to 2,900 mf/ml of blood, in a natural membrane apparatus. The results showed a variation between 92.3 percent and 98.8 percent of females fed. The exposure of the Cx. quinquefasciatus RECIFE population to different densities of microfilariae did not influence the mortality of the mosquitoes. Infective larvae from D. immitis were observed in the Malpighian tubules beginning on the 12th day, whereas larvae were observed in the head and proboscis beginning on the 13th day following infection. The vector efficiency index (VEI) presented by the mosquitoes ranged from 7.8 to 56.5. The data demonstrates that the Cx. quinquefasciatus RECIFE population has great potential for the transmission of D. immitis, as it allowed the development of the filarid until the infectious stage at the different densities of microfilariae to which it was exposed.

A Região Metropolitana do Recife é endêmica para Dirofilaria immitis e possui ambiente favorável para o desenvolvimento de Culex quinquefasciatus. Neste estudo avaliou-se a competência vetorial de Cx. quinquefasciatus população RECIFE para a transmissão de D. immitis. Para tanto, 2.104 fêmeas de Cx. quinquefasciatus população RECIFE foram expostas a diferentes densidades de microfilárias de D. immitis, variando de 1.820 a 2.900 mf/ml de sangue por meio de membrana natural. Os resultados obtidos demonstraram variação de 92,3 por cento a 98,8 por cento de fêmeas ingurgitadas após a alimentação. A exposição de Cx. quinquefasciatus população RECIFE a diferentes densidades de microfilárias não influenciou na mortalidade dos mosquitos. Larvas infectantes de D. immitis foram observadas nos túbulos de Malpighi a partir do 12º dia, enquanto na cabeça e na probóscide foram observadas a partir do 13º dia após a infecção. Os índices de eficiência vetorial (IEV) apresentados pelo culicídeo variaram de 7,8 a 56,5. Os dados obtidos demonstraram que Cx. quinquefasciatus população RECIFE tem grande potencial para a transmissão de D. immitis, pois permitiu o desenvolvimento do filarídeo até o estágio infectante nas diferentes densidades de microfilárias às quais foi exposto.

Focos de dirofilariose canina na Ilha do Marajó: um fator de risco para a saúde humana / Focus of canine heartworm disease in Marajó Island, North of Brazil: a risk factor for human health

A ocorrência de dirofilariose pulmonar humana relaciona-se com a prevalência de infecção por Dirofilaria immitis na população canina. Várias espécies de mosquitos são vetores desse nematóide. Analisaram-se amostras de sangue canino coletados nas vilas Pingo d'Agua e União, município de Salvaterra (Ilha do Marajó, PA), em junho, 2004 (n=34) e abril, 2005 (N=90). Os diagnósticos parasitológico e imunológico (ELISA - kit SNAP® 3DX™, Biobrasil) foram comparados (chi2, alfa=0,05) no exame de 34 amostras. A prevalência na população (N=90) foi avaliada pelo ELISA. O ELISA revelou mais positivos (25/34; 73,5 por cento) que a gota espessa (23/34, 67,6 por cento) e o Knott (21/34, 61,8 por cento), mas a diferença não foi significativa (p>0,05). A freqüência de infecção por D. immitis na faixa de 0 a 2 anos foi 58 por cento, enquanto em cães mais velhos foi 100 por cento. A prevalência da dirofilariose canina em Pingo d'Agua e Vila União foi alta (53,5 por cento), indicando risco de transmissão do parasito às pessoas nessa área.

The occurrence of human pulmonary dirofilariasis maintains a relation with the prevalence of Dirofilaria immitis infection in the canine population. Several mosquito species are vectors of this nematode. Canine blood samples collected in Pingo d'Agua and União villages, Salvaterra municipality (Marajó Island, Pará), in June, 2004 (n=34) and April, 2005 (N=90) were analyzed. Parasitological and immunological (ELISA - kit SNAP® 3DX™, Biobrasil) diagnoses were compared following the examination of 34 samples. The prevalence in the population (N=90) was evaluated by means of ELISA. ELISA revealed more positive samples (25/34; 73.5 percent) than thick smears (23/34, 67.6 percent) or Knott (21/34, 61.8 percent), but the differences were not significant (p>0.05). The frequency of D. immitis infection was 58 percent in dogs ranging from 0-2 years old, whereas in older dogs it was 100 percent. The prevalence of canine dirofilariasis was high in Pingo d'Agua and Vila União (53.5 percent), indicating the risk of parasite transmission to the people in this area.

Vector competence of Culex quinquefasciatus say from different regions of Brazil to Dirofilaria immitis

The vector competence of Culex quinquefasciatus from five localities in Brazil to Dirofilaria immitis was evaluated experimentally. Females from each locality were fed on an infected dog (~ 6 microfilariae/Ál blood). A sample of blood fed mosquitoes were dissected approximately 1 h after blood meal. These results demonstrated that all had ingested microfilariae (mean, 4.8 to 24.6 microfilariae/mosquito). Fifteen days after the infected blood meal, the infection and infective rates were low in all populations of Cx. quinquefasciatus. The mean number of infective larvae detected in the head and proboscis of these mosquitoes was 1-1.5. The vector efficiency, the number of microfilariae ingested/number of infective larvae, was low for all populations of Cx. quinquefasciatus. However, the survival rate for all populations was high (range 50-75 percent). The survival rate of Aedes aegypti assayed simultaneously for comparison was low (24.7 percent), while the vector efficiency was much higher than for Cx. quinquefasciatus. These data suggest that the vector competence of all assayed populations of Cx. quinquefasciatus to D. immitis in Brazil is similar and that this species is a secondary vector due to its low susceptibility. Nevertheless, vector capacity may vary between populations due to differences in biting frequency on dogs that has been reported in Brazil

Vectorial competence of Aedes aegypti (Linnaeus 1762) Rio de Janeiro Strain, to Dirofilaria immitis (Leidy 1856)

Dirofilaria immitis (Leidy 1856), a nematode parasite, is the etiologic agent of canine heartworm disease and mosquitoes are essential intermediate hosts. Mosquito susceptibility to the worms differ with species, strains and also among individuals of the same strain. To evaluate the degree of susceptibility of Rio de Janeiro laboratory raised strain of Aedes aegypti, we fed mosquitoes on canine blood with different densities of microfilariae (mf). There was no significant difference in the rate of development among the three different densities of mf. Infective larvae were found in the head and proboscis of all mosquitoes provided bloodmeals with different densities of mf after the 11th day post-infection. The infection rate of mosquitoes after ingestion of blood containing 3,000 mf/ml, 5,000 mf/ml and 7,000 mf/ml were 55.3 percent, 66.7 percent and 100 percent, respectively. The vector efficiency indices ranged from 1.6 to 9.3. The finding of L3 stage larvae, high infection rates and vector efficiency indices suggest that Ae. aegypti, Rio de Janeiro laboratory strain, is a potential vector of D. immitis, although of low efficiency

Survey of canine heartworm in the city of Recife, Pernambuco, Brazil

Six hundred and eleven random-source dogs (338 male, 273 female) one year of age or older, from six sections of the city of Recife, Pernambuco, were examined antemortem for circulating microfilariae Dirofilaria immitis and Dipetalonema reconditum adult heartworm (D. immitis) antigen, and examined postmortem for adult heartworms. The prevalence of heartworm infection was 2.3 per cent (14/611), as determined by necropsy for adult worms, and 1 per cent (6/611) had circulating microfilariae of D. immitis; thus, 57.1 per cent of the heartworm-infected dogs had occult infections. The results of serological testing indicated that 1.3 per cent (8/611) of the dogs were positive for adult heartworm antigen. A total of 42 (6.9 per cent) of the dogs had microfilariae of D. reconditum; 40 of these had only D. reconditum and two additional dogs had microfilariae of both species, D. immitis and D. reconditum.

Human pulmonary dirofilariasis: a review

Os autores realizaram minuciosa revisao sobre a distribuicao geografica, a clinica, a patologia e o diagnostico da dirofilariase pulmonar humana. Esta zoonose, que tem como principal agente etiologico a Dirofilaria immitis, e um problema medico porque produz um quadro clinico, embora benigno, que se confunde com neoplasia e, assim interpretado, pode conduzir o paciente a cirurgia do torax. Dos 229 casos citados na literatura, apenas 17 foram descritos no Brasil, apesar da existencia de condicoes muito favoraveis a transmissao da infeccao para o homem, admitindo-se portanto, que e uma parasitose subdiagnosticada. Finalmente, a importancia do diagnostico diferencial entre dirofilariase e neoplasias pulmonares nos casos de presenca de nodulo solitario subpleural ("coin lesion") e destacada, alem do que o desenvolvimento e aprimoramento de tecnicas modernas de diagnostico imunologico sao essenciais para distinguir esta doenca benigna de outras patologias mais serias e evitar cirurgias desnecessarias. Essas tecnicas poderao fornecer a prevalencia real da parasitose em nosso meio.

Dirofilariose pulmonar humana: relato de sete casos / Human pulmonary dirofilariasis: a report of seven cases

Dirofilariose pulmonar humana é uma doença rara causada pelo parasita Dirofilaria immitis. Apresenta-se usualmente como um nódulo pulmonar solitário que mimetiza câncer de pulmão. Embora considerada uma doença clinicamente benigna, uma biópsia pulmonar excisional é quase sempre necessária para o diagnóstico. Relatam-se as características epidemiológicas, clínicas e radiológicas de sete casos de dirofilariose pulmonar humana em Florianópolis. De sete pacientes relatados, seis tiveram como achado radiológico um nódulo pulmonar e foram submetidos à biópsia pulmonar excisional para o diagnóstico. Em um paciente, a imagem radiológica não estava disponível para revisão e, portanto, não foi descrita no trabalho; o diagnóstico foi estabelecido pela biópsia transbrônquica

Mosquitos vetores potenciais da dirofilariose canina na Regiäo Nordeste do Brasil / Mosquitoes potential vectors of canine hearthworm in the Northeast Region from Brazil

Introduçäo: Em alguns bairros costeiros de Säo Luís, Maranhäo, a prevalência da dirofilariose chega a mais de 40 por cento entre os cäes domiciliados. Porém, desconhecem-se os vetores naturais, tanto lá quanto no resto do Nordeste do país. O objetivo do estudo foi identificar os prováveis vetores dessa parasitose. Métodos: Realizaram-se coletas mensais de mosquitos em um bairro costeiro de Säo Luís, MA, de março de 1996 a maio de 1997, no peridomicílio, tendo cäo e homem como iscas. Os mosquitos foram dissecados para a pesquisa de larvas da Dirofilaria immitis. Resultados: Coletaram-se 1.738 mosquitos de 11 espécies. Culex quinquefasciatus, capturada todos os meses, porém menos freqüente na estaçäo chuvosa, correspondeu a 54,5 por cento do total, seguido Aedes albopictus (20,3 por cento), Aedes taeniorhynchus e Aedes scapularis (ambos 11 por cento). Larvas de D. immitis foram encontradas em 0,1 por cento dos Cx. quinquefasciatus e 0,5 por cento dos Ae. taeniorhynchus. Ae. taeniorhynchus e Cx. quinquefasciatus foram considerados vetores potenciais da dirofilariose em Säo Luís. A importância local de Cx. quinquefasciatus como transmissor primário da D. immitis necessita ser melhor avaliada

Búsqueda de Dirofilaria immitis en perros en la provincia Ciudad de La Habana / Searching of Dirofilaria immitis in dogs at Habana city province

Se informa que se estudiaron 2 281 perros en busca de infestación por Dirofilaria immitis. Se indica que se encontraron adultos en 10 de ellos (0,52%) y el 40% (265 perros) tenía microfilaremia. No se observó relación entre la densidad de microfilarias y el número de adultos. Se plantea que la microfilaremia fue mayor en los perros de raza indetinida y se encontraron adultos en la raza pastor alemán