The Distribution, Diversity, and Control of Dirofilariosis in Brazil: A Comprehensive Review.

Brazil's extensive coastline, tropical and subtropical climate, and well-preserved environment represent a conducive setting for dirofilariosis, a zoonotic mosquito-borne disease. Although this condition has long been recognised in the country, it has been relatively under-studied, and it is currently considered to be an emerging disease. Diagnosis, treatment, and control remain challenging due to the extensive gaps in knowledge. In order to help address this issue, this review aims to (i) summarise the available literature on the distribution of Dirofilaria spp. in Brazilian dogs over the last decade, (ii) review case reports of dirofilariosis in cats, wild animals, and humans over the last twenty years, and (iii) highlight the benefits of taking a One Health approach to managing this disease. While there have been several prevalence studies in dogs, disease distribution is poorly characterised in cats, and little is known about the occurrence of the parasite in wildlife. Human cases are sporadically reported, and no large-scale studies have been undertaken to date. Evidence indicates that Dirofilaria immitis is the main species circulating in Brazil, although Dirofilaria repens has also been detected. Molecular studies have also suggested the circulation of a highly virulent form of D. immitis, which may be genetically distinct from those of the Old World. A programme of epidemiological, ecological, genomic, and pathogenicity-based studies is required to quantify the impact of dirofilariosis in Brazil on both veterinary and public health and to inform others on its control.

Dirofilariasis of the Nasal Dorsum: A Case Report.

Dirofilariasis is an infection caused by the filarial nematode Dirofilaria. Dirofilaria immitis primarily causes pulmonary dirofilariasis, while subcutaneous dirofilariasis is usually caused by Dirofilaria tenuis and Dirofilaria repens but can rarely be caused by Dirofilaria immitis as well. Here we report a rare case where in a 26-year-old with a history of international travel presented with swelling over the nasal dorsum. Following surgical excision, histopathological examination revealed dirofilariasis. Although uncommon, this zoonosis should be taken into consideration as a differential diagnosis of facial swellings.

A Rare Case of Dirofilariasis in the Genian Region.

Dirofilariasis is an infectious disease caused by species of the Dirofilaria genus. It is manifested by the appearance of a subcutaneous swelling, especially in the eye region. We present the case of a 29-year-old patient who presented with facial asymmetry in the right genian region. Following clinical and paraclinical evaluations, the diagnosis of a parasitic cyst was established in the context of dirofilariasis with Dirofilaria repens (D. repens). Treatment consisted of surgical excision of the formation associated with prophylactic antibiotic medication. Macroscopic analysis of the excision piece revealed a structure that contained a cystic cavity and a filamentous form with a length of approximately 10 mm and a diameter of 1 mm. This is the first case of dirofilariasis located in the genian region reported in Romania. The overview of this pathology is important to raise awareness among physicians about its presence and clinical variations. Understanding such cases helps healthcare professionals enhance diagnostic skills, refine treatment strategies, and provide valuable insights into the prevalence and clinical presentation, fostering early detection and timely intervention. Detailed case reports contribute to the understanding of the disease's epidemiology, including risk factors and transmission patterns, which is essential for effective public health strategies.

Subcutaneous dirofilariasis in a 25-year-old male patient in Belgium on ultrasonography: a case report.

BACKGROUND: Subcutaneous dirofilariasis is a parasitic zoonosis commonly described in Canidae but rarely seen in humans. Most physicians are unfamiliar with this disease, especially in nonendemic areas, which can lead to medication error and diagnostic and treatment delay. To the best of our knowledge, no previous case of subcutaneous dirofilariasis preoperatively diagnosed on ultrasound has been described in Western Europe. CASE PRESENTATION: A 25-year-old Belgian male patient presented with a subcutaneous nodule in the epigastric region. Ultrasound investigation showed a typical cystic lesion with an internal serpiginous structure with echogenic lines, and there was active twirling movement of this serpentine structure during investigation, pathognomonic for subcutaneous dirofilariasis. Surgical extirpation was performed, and the diagnosis was histopathologically confirmed. CONCLUSION: Subcutaneous dirofilariasis has a characteristic appearance on ultrasound but is not well known in nonendemic areas, often leading to diagnostic delay and initial incorrect treatment. More knowledge of this disease and of its characteristic ultrasound appearance will hopefully lead to better patient care.

First report on natural infection by Dirofilaria repens in a cat in Spain: case report and literature review of feline subcutaneous dirofilariosis in Europe.

Dirofilaria repens is an endemic mosquito-borne pathogen widely spread throughout Europe and other non-Europen regions. Infection by D. repens has been reported in dogs, although little is known about the occurrence and epidemiological features of this nematode in cats. During the surgical procedure within the framework of a trap, neuter and release sterilization program, two female filarial nematodes with spontaneous movement were removed from the internal part of the spermatic cord from asymptomatic stray cat in Spain (Grao de Castellón, Castellon de la Plana, province of Spain). Moreover, the presence of microfilariae was detected by using three different methods, including direct blood smear technique, the microhematocrit tube test, and Knott´s modified test. PCR performed from the nematodes extracted from the spermatic cord and from microfilariae in EDTA-blood sample tested both positive for D. repens. To the authors' knowledge, this is the first report that demonstrates the presence of D. repens in cats in Spain. In this sense, a review of the current scientific status of feline subcutaneous dirofilariosis in Europe was also performed. Future investigations should analyze the epidemiological role of cats in D. repens infection including the prevalence of infection. Veterinarians working in endemic areas should be aware of this infection in cats and their susceptibility.

Genetic variability of Dirofilaria repens isolates from humans and dogs in Italy.

Dirofilaria repens is a paradigmatic example of an emerging vector-borne pathogen (VBP) in both human and veterinary fields. The spatial expansion and the increasing zoonotic impact of this VBP can be related to several drivers including the genetic structure of parasite populations. Italy is one of the European countries traditionally endemic with the highest incidence of canine and human cases of subcutaneous dirofilariosis. The present study aimed to assess the genetic identity and variability of D. repens isolates of human and canine origin from areas of Central Italy, compared with those isolated from different areas of Europe by sequence analysis of mtDNA genes (i.e., 12 S rDNA and cox1). A total of twenty isolates of D. repens were obtained from biopsies of subcutaneous and ocular cases of dirofilariosis occurring in 10 dogs and 10 humans. The sequence analysis of 12 S rDNA showed that all the sequences obtained clustered as a monophyletic group with a strong nodal support, indicating that all sequence types represented D. repens. The cox1 and the 12 S sequence analysis did not show host-related polymorphisms between human and dog-derived specimens. The sequence analysis of cox1 was performed including 8 additional sequences previously obtained from human and canine isolates in the same areas. Out of the 28 sequences analyzed, 20 were grouped in a haplogroup comprising 15 haplotypes (i.e., DR1, DR2, DR4, DR5, DR7, DR8, DR10-DR18), 2 sequences matched to DR9, reported for the first time in Italy, and 6 showed peculiar polymorphisms that were not previously described. The results obtained have implications for a better understanding of the epidemiology and phylogeography of this emerging vector-borne zoonotic parasite.

[A case of pleuropulmonary dirofilariasis caused by Dirofilaria repens. Case report].

The differential diagnosis of neoplasms of various localizations is the primary task in clinical practice of all physicians. We present a description of the case of invasion with Dirofilaria repens in the lung of a 68-year-old patient. In 2016 the patient was diagnosed with cancer of the left kidney and underwent a left-sided nephrectomy. During the dynamic observation in 2019, a lump was found in the left lung, which was regarded as a metastasis. An atypical SIX resection of the left lung was performed. Microscopy of the removed lump revealed the presence of a nematode of the genus Dirofilaria, presumably D. repens. The species identity of D. repens was confirmed by polymerase chain reaction using species-specific primers. It is known that the morphological identification of parasites up to the species in the surgical material presents certain difficulties and requires high professional training of the researcher. Therefore, the diagnosis of dirofilariasis in atypical localizations of nematodes in the human body is of great importance in the differentiation of malignant and benign formations, and the use of the polymerase chain reaction method can significantly increase the accuracy in establishing the final diagnosis.

Microfilaremic Dirofilaria repens Infection in Patient from Serbia.

We report a case of Dirofilaria repens infection causing microfilaremia in a patient from Serbia. Serum samples tested positive for D. repens IgG by ELISA. Our findings and those of others suggest the parasite's progressive adaptation to humans. Clinicians should be aware that microfilaremia can develop during Dirofilaria spp. infections.

Hematological characteristics of autochthonous hypermicrofilaremic dirofilariosis in dogs in Kannur District of Kerala.

This study aimed to determine whether autochthonous high-intensity D. repens microfilaremia leads to haematological changes in companion dogs. Dogs with hypermicrofilaremia presented to the District Veterinary Centre, Kannur were selected for the study. A total of 100 dogs were positive for hypermicrofilariaemia with D. repens based on peripheral blood smear examination and Knott's test. Of these, 3 dogs were concurrently positive for sheathed microfilaria (MF) of Brugia spp. Interestingly, an adult live worm of D. repens approximately eight cm in length was detected on a subcutaneous mass on the hind limb of a hypermicrofilaremic dog in the study. We compared the hematological parameters of 100 autochthonous hypermicrofilaremic dogs and 15 uninfected dogs. The hematological findings in the study are mild to moderate anemia, moderate to severe thrombocytopenia, leucocytosis with granulocytosis, lymphocytosis and monocytosis as compared to the uninfected group of dogs. The pathogenicity of naturally occurring hypermicrofilaremia is poorly studied, and knowledge of its epidemiology, host-parasite relationship and impact on various organs is warranted for better prevention and control, especially in hot-spot areas. Supplementary Information: The online version contains supplementary material available at 10.1007/s12639-023-01622-6.

How Italian practitioners manage dirofilariosis in dogs and cats? Data of a second national survey.

The zoonotic nematodes Dirofilaria immitis and Dirofilaria repens are endemic in many European countries and their distribution is changing. A correct diagnosis is the starting point to reduce their spread and veterinary practitioners represent the first line of defense against these two vector-borne diseases in pets and humans. With the aim to better understand current knowledge by veterinarians and to compare them with the previous survey, an online questionnaire was sent to Italian companion animal veterinary facilities. The overall response rate was 22.3%. Approximately 50% and 5% of facilities have diagnosed at least one case of Dirofilaria spp. in the last year in dogs and cats, respectively. In agreement with international guidelines, of the 665 facilities that responded to the questionnaire, 16.8% used Knott's test in combination with serology (Antigenic test-Ag-) to diagnose heartworm infection in dogs. For the diagnosis of D. repens infection, 13.8% used Knott's test in dogs and cats, and 10.5% used Knott's test only in dogs. Most facilities recommended beginning prevention of canine heartworm disease in April and ending in November. Injectable moxidectin and oral ivermectin were the two most commonly used preventives for D. immitis in dogs, while selamectin was most frequently used in cats. The drug most commonly used for heartworm adulticide treatment in dogs was melarsomine followed by the combined ivermectin-doxycycline treatment. The results of this study suggest that, on the one hand, veterinarians are aware of the recent developments in adulticide therapy, while on the other hand, diagnosis is not always made according to what is recommended by international guidelines and that the start and end times of prevention may not be optimal. Furthermore, the data show an increase in cases of coinfection compared to the previous survey.

Human subcutaneous dirofilariasis: A diagnostic dilemma.

Human dirofilariasis is a rare infection caused by filarial worms of genus Dirofilaria. Humans may be infected as aberrant (accidental) hosts, mainly by Dirofilaria repens and Dirofilaria immitis. Most of the cases reported in India are of ocular dirofilariasis, with a few reports on subcutaneous dirofilariasis. We hereby report one such case of human subcutaneous dirofilariasis affecting the neck region of a 63-year male patient from Assam. This case indicates that this infection is a potentially emerging zoonosis in Assam and there is scope of finding more such cases with surveillance.

Corrigendum: Emerging risk of Dirofilaria spp. infection in shelter dogs in southern Italy.

[This corrects the article DOI: 10.3389/fvets.2023.1112036.].

Ocular dirofilariasis: A report from Odisha.

We report a case of ocular dirofilariasis in a 68-year-old man manifesting as pre-septal abscess with gradually increasing swelling of the left eyelid and near complete ptosis of eye. A live worm was seen wriggling in the lesion while the abscess was being drained and was extracted carefully. Subsequently, it was identified as an adult female Dirofilaria repens worm. The lid edema and swelling resolved and the patient was discharged without any residual complaints.

Genetic diversity and characterization of Wolbachia endosymbiont in canine filariasis.

Canine filariasis is caused by nematodes from the family Onchocercidae, which is transmitted by arthropod vectors. The disease is commonly found in Southeast Asia and exists worldwide. Some filarial nematodes are associated with intracellular bacteria of the genus Wolbachia, which plays an important role in embryogenesis, molting, and the long-term survival of adult worms. This study aims to characterize Wolbachia sp. and determine the association between Wolbachia and canine filarial nematode species in Thailand. A total of 46 dog blood samples that were naturally infected with filarial nematodes were obtained to identify filarial nematode species by Giemsa stained under a light microscope and confirmed using the molecular technique. In order to characterize Wolbachia sp., the nested PCR assay targeting the 16S rRNA gene showed that all samples of Dirofilaria immitis and fifteen samples of Candidatus Dirofilaria hongkongensis were grouped into Wolbachia supergroup C. In addition, all samples of Brugia spp. and five samples of Candidatus Dirofilaria hongkongensis were classified into Wolbachia supergroup D. The genetic diversity analysis conducted using the 16S rRNA gene revealed a similar result when analyzed through phylogenetic tree analysis. This is the first genetic diversity study of Wolbachia of Candidatus Dirofilaria hongkongensis in infected dogs in Thailand.

Removal and identification of a subconjunctival parasite by light and scanning electron microscopy.

Background: Ophthalmic dirofilariasis is an uncommon zoonotic parasitic infection caused by species of Dirofilaria, a dog tapeworm that is transmitted to human by mosquitoes. Man is a dead-end host for the parasite. Ophthalmic involvement is rare and includes periorbital, subconjunctival, subtenon, and intra-ocular involvement. We report the removal of a subconjunctival worm and identification by light microscopy (LM) and scanning electron microscopy (SEM). Purpose: : A 62-year-old female presented with complaints of redness, discharge, and foreign body sensation with difficulty in opening eyes in the left eye for the last 3 days. The patient is a non-vegetarian. On examination, her best corrected visual acuity in both eyes was 20/20. On slit lamp examination, there was a long, thin, round, coiled white subconjunctival live worm in the left eye superiorly. The rest of anterior segment evaluation, intra-ocular pressure, and fundus was normal in both eyes. The parasite was removed under local anesthesia from subconjunctival space [Video]. External surface morphology under LM revealed fine transverse cuticular striations with tapered cephalic and caudal ends. Uterus was long and coiled with indistinguishable masses inside. The finding was also confirmed by SEM. Synopsis: A subconjuctival parasite was removed and identified as Dirofilaria repens by characteristic LM and SEM findings. Highlight: Dirofilaria species may lodge in many tissues of human bodies including eye and adnexa. Dirofilaria is a natural parasite of carnivorous animals, mostly dogs, cats, and foxes.[1] The most common mode of transmission to human is usually by bite of mosquitoes like Culex and Aedes, which are considered as vectors, and it is often thought that parasitemia is because of accidental conduction.[1] Simple surgical removal of the worm is curative. After removal, the worm should be visualized directly under LM. All the internal structures of the transparent worm could be seen and compared with those under SEM.

Unusual Masquerading Infraorbital Mass-A Case Report of Human Ocular Dirofilariosis Found in A Ukrainian Patient in Switzerland.

A 78-year-old Ukrainian woman who had immigrated to Switzerland presented with a rapid growing subcutaneous infraorbital mass. Surgical excision of the mass revealed a well-circumscribed, encapsulated tumor, adherent to the skin. The excision showed a soft tissue inflammation with parts of Dirofilaria spp. The number of cases of human dirofilariosis reported in the last 50 years has gradually increased. Dirofilaria repens is now endemic in many countries and is currently considered to be one of the fast spreading zoonoses in Central, Eastern and Northern Europe. The first empirical evidence of Swiss spreading of D. repens infections was in a dog from southern Switzerland in 1998. Ours is the first case of human orbital dirofilariosis found in a Ukranian patient reported in Switzerland. Our purpose is to inform the ophthalmologist to consider orbital dirofilariosis in the differential diagnosis of inflammatory masses of the orbit and to warn about the spread of this infection in Switzerland.

Emerging risk of Dirofilaria spp. infection in shelter dogs in southern Italy.

In southern Italy, the number of autochthonous cases of Dirofilaria immitis in dogs has increased considerably. This also occurs in the Campania region, particularly in coastal areas, where infections with D. immitis and Dirofilaria repens have been reported more frequently. Therefore the aim of the present study was to better investigate the occurrence of Dirofilaria spp. in a local dog shelter in Castel Volturno (Campania region, southern Italy). Briefly, a total of 260 blood samples were analysed for identification of microfilariae (mff) and detection of Dirofilaria immitis antigen. Dogs were classified according to their age (1-3 years; 4-6 years; 7-11 years; > 11 years) and length of stay in the shelter at the time of sampling (dogs that entered in the shelter in the last 4 months; dogs housed in the shelter for more than 4 months up to 2 years; dogs housed for more than 2 years). The modified Knott's test revealed that 195 dogs (75.0%) were positive for circulating mff of Dirofilaria spp. Specifically, 104/260 (40.0%) dogs were positive for D. immitis and 91/260 (35.0%) were positive for D. repens. In addition, 72/260 (27.7%) dogs had both D. immitis and D. repens mff. Antigen testing revealed that 78/260 (30.0%) dogs were positive for D. immitis. However, 26/104 (25.0%) of the dogs with D. immitis mff were antigen-negative. The overall k concordance between the modified Knott's test and the antigenic test was ≤0.2 (poor) (p = 0.000). The results of the logistic regression model showed a significant association between Dirofilaria exposure and the period of time the dogs had spent in the shelter at the time of sampling. Dogs housed in the shelter for 4 months (group 1) and between 4 months and 2 years (group 2) had higher Dirofilaria positivity than dogs in group 3 (housed for more than 2 years) (80.4% vs. 79.6% vs. 62.4%, respectively). Moreover, male dogs and older dogs (between 7 and 11 years of age) were more likely to be infected with Dirofilaria spp.

Unusual cause of unilateral facial oedema: intramuscular dirofilariasis.

INTRODUCTION: Unilateral facial oedema may occur due to inflammatory, infective, or cystic pathology; patients often seek medical help at an early stage. CASE REPORT: We report one such case caused mimicking a parotid abscess, caused by dirofilariasis. CONCLUSION: Dirofilariasis is an emerging zoonosis and should be considered a differential diagnosis of atypical facial swelling. It is equally important for clinicians, radiologists, and pathologists to be familiar with the diagnostic characteristics to avoid misdiagnosis.

[Occurrence of canine subcutaneous dirofilariosis (Dirofilaria repens) in Switzerland]. / Vorkommen des Hautwurms Dirofilaria repens bei Hunden in der Schweiz.

INTRODUCTION: Infectious diseases are increasingly introduced into Switzerland due to the increased travel activity in recent decades and the import of dogs. Dirofilariasis, caused by Dirofilaria immitis or D. repens, is one of them. An infection with D. repens, the cause of canine subcutaneous dirofilariosis, is often asymptomatic in dogs, but represents a potential zoonotic disease risk for humans. Due to the rapidly increasing number of human cases, D. repens is considered an emerging zoonosis in north-eastern Europe. The prevalence of D. repens infections in dogs and humans in Switzerland is unknown. Since 2016 the analysing diagnostic laboratory provided with the newly introduced filaria PCR a realiable diagnostic test to differentiate betweeen D. immitis and D. repens. Total nucleic acid (DNA and RNA) was extracted from 200 µl EDTA blood without prior enrichment followed by a species-specific real-time PCR assay. The analyses for Dirofilariae in the years 2016 to 2021 were examined in a descriptive retrospective study and the proportion of positive tests per year (prevalence with 95 % confidence interval) was calculated. Furthermore, blood samples of 50 imported dogs to Switzerland were analyzed in an exploratory cross-sectional study for the presence of dirofilaria. No D. repens positive case was found in the first two years after the introduction of the PCR. In 2018 five of 546 analyzed samples (5/546, 0,9 %, 95 % confidence interval [95 % CI]=0,7 - 1,2 %) tested positive for D. repens, in 2019 four of 591 (0,7 %, 95 % CI=0,5 - 0,9 %), in 2020 15 of 783 (1,9 %, 95 % CI=1,6 - 2,3 %) and in 2021 eleven of 1058 samples (1,0 %, 95 % CI=0,8 - 1,3 %). In the exploratory cross-sectional study, four of the 50 examined dogs were positive for D. repens (8 %, 95 % CI=2,6 - 20,1 %). One dog had a concurrent infection with D. immitis and D. repens. All four positive tested dogs were imported from Hungary. Potentially zoonotic infections with D. repens occur in dogs living in Switzerland. This disease should be included in the differential diagnoses of imported dogs and a monitoring during routine health checks should be done more often. The veterinary profession can thus assume its responsibility for the prevention of zoonoses as part of a One Health approach.

INTRODUCTION: Au cours des dernières décennies, des maladies infectieuses sont de plus en plus souvent introduites en Suisse en raison de l'augmentation des voyages et de l'importation de chiens. La dirofilariose, causée par Dirofilaria immitis ou D. repens, est une de ces maladies. Une infection par D. repens, responsable de la dirofilariose sous-cutanée canine, est souvent asymptomatique chez le chien, mais elle représente un risque potentiel de zoonose pour l'homme. En raison de l'augmentation rapide du nombre de cas humains, D. repens est une zoonose émergente dans le nord-est de l'Europe. La prévalence des infections à D. repens chez les chiens et les humains en Suisse est inconnue. L'introduction de la PCR des filaires dans le laboratoire d'analyse permet depuis 2016 de faire une distinction fiable entre D. immitis et D. repens. L'acide nucléique total (ADN et ARN) a été extrait de 200 µl de sang EDTA sans enrichissement préalable, suivi d'un test PCR en temps réel spécifique à l'espèce. Les résultats des analyses de la dirofilariose de 2016 à 2021 ont été examinés dans une étude rétrospective descriptive et la proportion de tests positifs par an (prévalence avec un intervalle de confiance de 95 %) a été calculée. En outre, des échantillons de sang de 50 chiens importés en Suisse ont été analysés dans le cadre d'une étude transversale exploratoire pour la présence de dirofilaires. Aucun cas positif à D. repens n'a été trouvé au cours des deux premières années suivant l'introduction de la PCR. En 2018, cinq des 546 échantillons analysés (5/546, 0,9 %, intervalle de confiance à 95 % [95 %CI]=0,7­1,2 %) ont été testés positifs pour D. repens, en 2019 quatre des 591 (0,7 %, CI 95 %=0,5 ­ 0,9 %), en 2020 15 des 783 (1,9 %, CI 95 %=1,6 ­ 2,3 %) et en 2021 onze des 1058 échantillons (1,0 %, CI 95 %=0,8 ­ 1,3 %). Dans l'étude transversale exploratoire, quatre des 50 chiens examinés étaient positifs pour D. repens (8 %, CI à 95 % = 2,6 ­ 20,1 %). Un chien présentait une infection concomitante par D. immitis et D. repens. Les quatre chiens testés positifs avaient été importés de Hongrie. Des infections potentiellement zoonotiques par D. repens se produisent chez des chiens vivant en Suisse. La surveillance de cette maladie devrait être davantage incluse dans les contrôles de santé de routine et dans les diagnostics différentiels chez les chiens importés. La profession vétérinaire peut ainsi assumer sa responsabilité dans la prévention des zoonoses dans le cadre d'une approche One Health.