Animal and Human Dirofilariasis in India and Sri Lanka: A Systematic Review and Meta-Analysis.

Dirofilariasis is an emerging vector-borne tropical disease of public health importance that mainly affects humans and dogs. Dirofilaria immitis and D. repens are the two well-documented dirofilariasis-causing filarioid helminths of both medical and veterinary concerns in India and Sri Lanka. This systematic review and meta-analysis aimed to describe and summarize the current evidence of dirofilariasis prevalence and distribution in India and Sri Lanka. Interestingly, D. repens is reported to circulate in both dogs (prevalence of 35.8% (95% CI: 11.23-60.69)) and humans (97% of published case reports) in India and Sri Lanka, but D. immitis is reported to be present in the dog populations in India (prevalence of 9.7% (95% CI: 8.5-11.0%)), and so far, it has not been reported in Sri Lanka. This peculiar distribution of D. immitis and D. repens in the two neighbouring countries could be due to the interaction between the two parasite species, which could affect the pattern of infection of the two worm species in dogs and thus influence the geographical distribution of these two filarial worms. In medical and veterinary practice, histopathology was the most commonly used diagnostic technique (31.3%; 95% CI 2.5-60.2%). The low specificity of histopathology to speciate the various Dirofilaria spp. may lead to misdiagnosis. It was identified in this study that several regions of India and Sri Lanka have not yet been surveyed for dirofilariasis. This limits our understanding of the geographical distribution and interspecies interactions of the two parasites within these countries. Parasite distribution, disease prevalence, and interspecies interactions between the vectors and the host should be targeted for future research.

Heartworm Disease in Jackals: Unusual Location of Dirofilaria immitis.

PURPOSE: The knowledge of heartworm disease in free ranging wild canid populations is limited. As it is very difficult to monitor this disease in live animals, sporadic findings are mostly obtained by examining culled individuals of game species. METHODS: As a part of a broader study on jackal (Canis aureus) ecology in Serbia, the necropsy of legally hunted animals was performed in 2020. RESULTS: Two cases of heartworm infection with unusually located adult heartworms were diagnosed. The first case is an adult female jackal harvested in the vicinity of the capital city of Belgrade. Three adult specimens of Dirofilaria immitis were found in the right atrium of the heart, and nine adult specimens were located at an atypical site, in the vena cava caudalis. Very similar, the second case was in an adult female jackal harvested in the vicinity of Backi Monostor. In this case, six adult specimens of D. immitis were found in the right atrium of the heart and six more adult specimens in the vena cava caudalis. CONCLUSION: Although this nematode generally resides in the pulmonary arteries and the right ventricle of the heart, rare findings in other large blood vessels can occur. To the best of our knowledge, these are the first and only two confirmed cases of adult D. immitis found in vena cava caudalis in jackals in Europe.

Human Pulmonary Dirofilariasis: A Review for the Clinicians.

Human pulmonary dirofilariasis (HPD) is a rare zoonotic disease caused by Dirofilaria immitis, the nematode responsible for canine cardiopulmonary dirofilariasis (dog heartworm). The incidence of HPD is on the rise throughout the world due to increased awareness and factors affecting the vector (mosquito). Humans are accidental hosts for D. immitis. Most patients are asymptomatic and present with an incidental pulmonary nodule that mimics primary or metastatic pulmonary malignancy. Some patients suffer from pulmonary and systemic symptoms in the acute phase of pneumonitis caused by pulmonary arterial occlusion by the preadult worms resulting in pulmonary infarction and intense inflammation. These patients may have ill-defined pulmonary infiltrate on chest radiology. Pulmonary nodules represent the end result of initial pneumonitis. There are no specific clinical, laboratory, or radiologic findings that differentiate HPD from other causes of a pulmonary nodule. Although serologic tests exist, they are usually not commercially available. The majority of patients are diagnosed by histopathologic identification of the decomposing worm following surgical resection of the lesion.

Serological Survey of Canine Vector-Borne Infections in North-Center Spain.

Various factors are currently causing an increase in vector-borne parasitic diseases at a global scale; among them, some stand out, such as climatic disturbances derived from global change, the increase in movements of reservoir animals, or changes in land made by human activity. In the European continent, there have been an increasing number of epidemiological studies focused on the detection of these diseases, especially in dogs. In Spain, there are few epidemiological studies focused on the evaluation of the biotic and abiotic factors that may influence the distribution, such as climatic zones, orography, or presence of water reservoirs. The aim of this study was to analyze the prevalence and distribution of several canine vector-borne diseases caused by Dirofilaria immitis, Leishmania infantum, Anaplasma platys, and Ehrlichia canis in the autonomous community of Castilla y León, the largest region of the Iberian Peninsula, providing a geospatial approach based on a geographic information system (GIS) analysis. Blood from a total of 1,475 domestic dogs from the nine provinces of Castilla y León were analyzed. Also, a GIS analysis of the sample locations was carried out, taking into account the most important predictor variables. The prevalence in dogs infected by D. immitis was 7.19%, and the seroprevalence by L. infantum was 4.61 and 1.56% for A. platys and E. canis. Most of the infected animals were located in areas with stagnant water, irrigated agriculture, or riverbanks, always close to forest and woodland vegetation. These results indicate that dogs living in Castilla y León should take prophylactic measures to avoid infections.

Anthology of Dirofilariasis in Russia (1915-2017).

Dirofilariasis is a helminths vector-borne disease caused by two species of Dirofolaria-D.repens and D.immitis. The former is overwhelmingly associated with human dirofilariasis. The vector of the worm are mosquitoes of the family Culicidae (largely Culex, Aedes and Anopheles). The definitive hosts of Dirofilaria are dogs and to a lesser extent cats. Humans are an accidental host. A total of 1200 human cases caused by Dirofilaria were registered in the territory of the ex-USSR during the period 1915-2016. Zonal differences have been seen in the prevalence of infected dogs and mosquitoes. Studies undertaken in the southern part of the Russian Federation (RF) revealed the prevalence of Dirofilaria in dogs to be 20.8% with wild variations of larva density. Studies carried out in the central part of the RF found that the prevalence of parasites in dogs was 4.1%. Aedes mosquitoes were infected less than Culex and Anopheles mosquitoes. The latter were infected by D. repens more often than Culex and Aedes. Zonal differences were also traced in regard to Dirofilaria prevalence in humans, thus allowing identification of three zones of risk of infection (low, moderate, and stable), reflected in a series of constructed maps. Although Dirofilariasis was known on the territory of Russia from 1915, only sporadic cases of the disease were reported occasionally. Its number was showed an increasing trend only during the 1980s-1990s, reaching the level of hundreds of cases. The majority of cases were confined to the southern parts of Russia with geographic coordinates of 43°-45° on the northern latitude. Comparison of the timing of the global trend of climate warming during the 1990s with the temporal pattern of Dirofilaria on the territory of Russia during the same period demonstrated a close association between two phenomena. With the continuous process of global climate warming, the incidence of dirofilariasis both in man and dogs goes unabated exemplified by the territorial expansion of the disease northwards and eastwards attaining the latitude of 56°-57° on the northern latitude in the European and Asian parts of Russia. It appears that within the period of the last 20-25 years, the population at risk has doubled. Under these circumstances, dirofilariases in Russia should be considered as an emerging public health problem necessitating the establishment of a comprehensive epidemiological monitoring system with strong entomological and veterinary components. Based on the results obtained, an appropriate control intervention could be developed.

Optimized protocol for DNA/RNA co-extraction from adults of Dirofilaria immitis.

Dirofilaria immitis, the etiologic agent of canine heartworm disease, like several other filarial nematodes, harbors the bacterial endosymbiont Wolbachia. To investigate metabolic and functional pathways of D. immitis and Wolbachia individually, along with their interactions, the use of both transcriptomic and genome analysis has becoming increasingly popular. Although several commercial kits are available for the single extraction of either DNA or RNA, no specific protocol has been described for simultaneous extraction of DNA and RNA from such a large organism like an adult D. immitis, where female worms generally reach ∼25 cm in length. More importantly, adult worms of D. immitis can only be obtained either through necropsy of experimentally infected dogs or by minimally-invasive surgical heartworm removal of naturally infected dogs. This makes each individual worm sample extremely important. Thus, in the context of a project aimed at the evaluation of both gene expression analysis and Wolbachia population assessment following different treatments, an optimized protocol for co-extraction of DNA and RNA from a single sample of adult D. immitis has been developed. •An optimized method for DNA/RNA co-extraction from large size nematodes using TRIzol® reagent.•Allows maximum exploitation of unique samples as adults of D. immitis.

Molecular Analysis of Canine Filaria and Its Wolbachia Endosymbionts in Domestic Dogs Collected from Two Animal University Hospitals in Bangkok Metropolitan Region, Thailand.

Canine filariasis is caused by several nematode species, such as Dirofilaria immitis, Dirofilaria repens, Brugia pahangi, Brugia malayi, and Acanthocheilonema reconditum. Zoonotic filariasis is one of the world's neglected tropical diseases. Since 2000, the World Health Organization (WHO) has promoted a global filarial eradication program to eliminate filariasis by 2020. Apart from vector control strategies, the infection control of reservoir hosts is necessary for more effective filariasis control. In addition, many studies have reported that Wolbachia is necessary for the development, reproduction, and survival of the filarial nematode. Consequently, the use of antibiotics to kill Wolbachia in nematodes has now become an alternative strategy to control filariasis. Previously, a case of subconjunctival dirofilariasis caused by Dirofilaria spp. has been reported in a woman who resides in the center of Bangkok, Thailand. Therefore, our study aimed to principally demonstrate the presence of filarial nematodes and Wolbachia bacteria in blood collected from domestic dogs from the Bangkok Metropolitan Region, Thailand. A total of 57 blood samples from dogs with suspected dirofilariasis who had visited veterinary clinics in Bangkok were collected. The investigations for the presence of microfilaria were carried out by using both microscopic and molecular examinations. PCR was used as the molecular detection method for the filarial nematodes based on the COI and ITS1 regions. The demonstration of Wolbachia was performed using PCR to amplify the FtsZ gene. All positive samples by PCR were then cloned and sequenced. The results showed that the filarial nematodes were detected in 16 samples (28.07%) using microscopic examinations. The molecular detection of filarial species using COI-PCR revealed that 50 samples (87.72%) were positive; these consisted of 33 (57.89%), 13 (22.81%), and 4 (7.02%) samples for D. immitis, B. pahangi, and B. malayi, respectively. While the ITS1-PCR showed that 41 samples (71.93%) were positive-30 samples (52.63%) were identified as containing D. immitis and 11 samples (19.30%) were identified to have B. pahangi, whereas B. malayi was not detected. Forty-seven samples (82.45%) were positive for Wolbachia DNA and the phylogenetic tree of all positive Wolbachia was classified into the supergroup C clade. This study has established fundamental data on filariasis associated with Wolbachia infection in domestic dogs in the Bangkok Metropolitan Region. An extensive survey of dog blood samples would provide valuable epidemiologic data on potential zoonotic filariasis in Thailand. In addition, this information could be used for the future development of more effective prevention and control strategies for canine filariasis in Thailand.

Dirofilaria immitis infestation in imported police (K-9) dogs in Iraq: clinicopathological and molecular investigations study / Infecção por Dirofilaria immitis em cães policiais importados no Iraque: estudo clínico-patológico e de investigações moleculares

Dirofilaria immitis, the cause of heartworm infestation (HWI) or dirofilariasis, affects members of the Canidae and remains a worldwide clinical problem. In Iraq, dirofilariasis was believed absent until 2009, when the Karbala Governorate was reported as an endemic area for canine dirofilariasis. Consequently, this study intended to investigate the occurrence of Dirofilaria immitis in police dogs in one police academy in Iraq and to study the gross and histopathological changes in 5 dead dogs, as well as to identify the species of the causative parasite using PCR technique. Thirty-nine police dogs, aged between 6 months and 12 years were included in this study. For the microfilariae investigation, 5 ml blood samples were collected from all dogs in EDTA tubes and examined by Knott's method. The systemic necropsy performed in five dead dogs showed severe clinical signs of dirofilariasis and tissue specimens were sent for routine histopathological processing. For the molecular analysis, adult worms of the detected Dirofilaria spp. were used for DNA extraction and amplification of the cox1 gene. Fifteen of 39 (38.46%) dogs were diagnosed with moderate to severe microfilariasis. The dead dogs revealed typical severe clinical signs of dirofilariasis. Moreover, typical gross and histopathological changes were also seen, accompanied by generalized thromboembolic lesions, suggesting the occurrence of the caval syndrome. The PCR investigation confirmed that D. immitis was the species present in Iraq. In conclusion, this study establishes that Iraq is a newly reported endemic area for dirofilariasis. Moreover, the infestation occurring in these cases most probably happened inside Iraq. The authors recommend doing further epidemiological studies concerning the occurrence of D. immitis in local dogs as well as in the imported dogs in all Iraqi governorates to better understand the epidemiological map of this disease and to introduce an active treatment and preventive program. Awareness and education regarding this disease should be provided to the veterinarians, dog guiders and people in direct contact with dogs, as this disease is one of the important zoonotic diseases.(AU)

A Dirofilaria immitis, causadora da infestação pelo verme do coração (IVC) ou dirofilariose afeta os membros da família Canidae e ainda é um problema clínico mundial. Até o ano de 2009, acreditava-se que o Iraque fosse livre da dirofilariose, porém nessa ocasião a governadoria de Kerbala foi relatada como uma área endêmica de dirofilariose. Assim, o presente trabalho foi realizado para investigar a ocorrência da Dirofilaria immitis em cães policiais em uma academia de polícia do Iraque, estudar as alterações macroscópicas e histopatológicas em cinco cães mortos, bem como, identificar as espécies do parasita causador com o emprego da técnida de PCR. Trinta e nove cães policiais com 6 meses a 12 anos de idade foram incluídos no estudo. Amostras de sangue de cinco mililitros foram colhidas por animal, em tubos com EDTA e foram examinadas pelo método de Knott. A necropsia sistêmica foi realizada em cinco cães que haviam apresentado sinais clínicos severos de dirofilariose e espécimens dos seus tecidos foram enviados para o processamento histopatológico de rotina. Para a análise molecular dos vermes adultos de Dirofilaria spp, foi empregada a extração do DNA e a amplificação do gene cox1. Quinze de 39(38,46%) cães foram diagnosticados com uma microfilariase variável de moderada para severa. As alterações macroscópicas e histopatológicas foram acompanhadas por lesões generalizadas tromboembólicas sugestivas da ocorrência da síndrome da veia cava. A investigação de PCR confirmou que a D.immitisera a espécie presente no Iraque. A conclusão do estudo estabeleceu que o Iraque deve passar a ser considerado como uma nova área endêmica da dirofilariose. Além da infestação registrada nos casos descritos é provável que ela também esteja presente em outras regiões do Iraque. Os autores recomendam a realização de estudos epidemiológicos para investigar a ocorrência de D.immitis tanto nos cães locais bem como em cães importados em todas as governadorias do Iraque, para ser construído o mapa epidemiológico da distribuição da doença e implantadas as ações de tratamento e de um progrma preventivo. Ações de educação em saúde sobre a doença deverão ser dirigidas para os veterinários, tratadores de cães e para pessoas em geral que tenham contato com os cães, pois esta doença é uma importante zoonose.(AU)

18-FDG Uptake in Pulmonary Dirofilariasis.

Solitary pulmonary nodules are a common finding on chest radiography and CT. We present the case of an asymptomatic 59-year-old male found to have a 13 mm left upper lobe nodule on CT scan. The patient was asymptomatic and the CT was performed to follow up mediastinal and hilar lymphadenopathy that had been stable on several previous CT scans. He had a history of emphysema and reported a 15 pack-year smoking history. PET-CT was performed which demonstrated mild 18-FDG uptake within the nodule. Given his age and smoking history, malignancy was a consideration and he underwent a wedge resection. Pathological examination revealed a necrobiotic granulomatous nodule with a central thrombosed artery containing a parasitic worm with internal longitudinal ridges and abundant somatic muscle, consistent with pulmonary dirofilariasis. Dirofilaria immitis, commonly known as the canine heartworm, rarely affects humans. On occasion it can be transmitted to a human host by a mosquito bite. There are two major clinical syndromes in humans: pulmonary dirofilariasis and subcutaneous dirofilariasis. In the pulmonary form, the injected larvae die before becoming fully mature and become lodged in the pulmonary arteries.