Molecular Study of Dirofilaria immitis and Dirofilaria repens in Dogs from Tunisia

Diversity of biting midges, mosquitoes and sand flies at four dog shelters in rural and peri-urban areas of Central Morocco

Blood-feeding arthropods are involved in the transmission of several pathogens that have a major impact on public health. Entomological investigations highlighted the composition, abundance, and diversity of flying hematophagous arthropods at four dog shelters located in central Morocco during an eight-month study, with the aim of discussing their vectorial roles and assessing the risk of these shelters as foci for zoonotic diseases. Monitoring of the arthropod fauna for 64 catch nights resulted in the collection of 2,321 biting midges (Ceratopogonidae), 570 mosquitoes (Culicidae), and 475 sand flies (Psychodidae). Fourteen Culicoides species were recorded and dominant species were Culicoides imicola (55.96%), C. paolae (16.07%), C. circumscriptus (10.29%), and C. newsteadi (5.77%). Three mosquito species were collected, including Culex pipiens s.l. (96.84%), Culiseta longiareolata (2.80%), and Cx. perexiguus (0.36%). Ten sand fly species were collected, including seven Phlebotomus species (62.70%) and three Sergentomyia species (37.30%); Sergentomyia minuta was the most dominant species (34.31%), followed by Phlebotomus sergenti (32.42%), typical Ph. perniciosus (8.63%), Ph. alexandri (6.94%), and Ph. riouxi (6.52%). The coexistence of several vectors in these study areas indicates the potential circulation of a wide range of pathogens, including zoonotic ones, thus requiring the implementation of surveillance and control programs to prevent the emergence and spread of disease outbreaks.

Diversity and geographic distribution of haplotypes of Dirofilaria immitis across European endemic countries

BACKGROUND

Dirofilaria immitis, also known as heartworm, is one of the most important parasitic nematodes of domestic dogs, causing a potentially serious disease, cardiopulmonary dirofilariosis, which can be lethal. This species seems to be less 'expansive' than its sister species Dirofilaria repens, and it is believed that climate change facilitates the spread of this parasite to new non-endemic regions.

METHODS

In total, 122 heartworm isolates were analysed from nine endemic countries in Europe (Portugal, Spain, Italy, Greece, Hungary, Romania, Slovakia, and Ukraine) and a single isolate from Bangladesh by amplification and sequencing of two mitochondrial (mt) DNA markers: cytochrome c oxidase subunit 1 (COI) and dehydrogenase subunit 1 (NADH). The main aim of the current study was to determine the genetic diversity of D. immitis and compare it with D. repens haplotype diversity and distribution. DNA was extracted from adult heartworms or microfilariae in blood. Most isolates originated from dogs (Canis lupus familiaris) while 10 isolates originated from wildlife species from Romania, including eight isolates from golden jackals (Canis aureus), one isolate from a Eurasian otter (Lutra lutra) and one isolate from a red fox (Vulpes vulpes).

RESULTS

Median spanning network analysis was based on the combined sequence (1721 bp) obtained from two mt markers and successfully delineated nine haplotypes (Di1-Di9). Haplotype Di1 was the dominant haplotype encompassing 91 out of the 122 sequences (75%) from all nine countries and four host species. Haplotype Di2 was the second most common haplotype, formed solely by 13 isolates from Italy. The remaining sequences were assigned to Di3-Di9 haplotypes, differing by 1-4 SNPs from the dominant Di1 haplotype. There was evidence for geographical segregation of haplotypes, with three unique haplotypes associated with Italy and four others associated with certain countries (Di4 and Di7 with Slovakia; Di8 with Greece; Di6 with Hungary).

CONCLUSION

Diversity in D. immitis mt haplotypes was lower by half than in D. repens (9 vs. 18 haplotypes in D. immitis and D. repens, respectively), which may be associated with the slower expansion of heartworm in Central and NE Europe. NADH gene appears to be conserved in Dirofilaria sp. by showing lower genetic diversity than the analysed COI gene.

The prevalence of canine dirofilariasis in China: a systematic review and meta-analysis

BACKGROUND

Dirofilariasis, the disease caused by Dirofilaria spp., and in particular by Dirofilaria immitis and Dirofilaria repens in canines, occurs frequently in canids and felids, and occasionally in humans, in temperate, sub-tropical and tropical regions globally. Although highly effective, safe and convenient preventive medicines have been available for the treatment of dirofilariasis for the past three decades, the disease remains a major veterinary and public health concern in endemic areas. The insect vectors, host-parasite relationships and interactions of Dirofilaria spp. have received little attention in China, and there is very little information in English regarding the prevalence of dirofilariasis in animals and humans in the country. The aim of this systematic review and meta-analysis is to evaluate the status of canine dirofilariasis in China based on the available literature in English and in Chinese.

METHODS

We systematically searched five databases for epidemiologic studies on the prevalence of canine dirofilariasis in China and finally selected 42 studies eligible for inclusion in the systematic review and meta-analysis. The meta-analysis was performed using the random effects model in the meta package in R v4.2.1.

RESULTS

The random effects model gave a pooled and weighted prevalence of Dirofilaria infection among dogs in China in the past 100 years of 13.8% (2896/51,313, 95% confidence interval 8.2-20.4%) with a high level of heterogeneity (I² =  99.5%).

CONCLUSIONS

Our analyses indicated that the prevalence of canine dirofilariasis in China has gradually declined, but that the range of Dirofilaria spp. has expanded. Older and outdoor dogs presented a higher rate of positive infection. The findings indicated that more attention should be paid to host factors for the effective control and management of this disease.

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.

Mosquito Vectors (Diptera: Culicidae) and Mosquito-Borne Diseases in North Africa

Mosquitoes (Diptera: Culicidae) are of significant public health importance because of their ability to transmit major diseases to humans and animals, and are considered as the world's most deadly arthropods. In recent decades, climate change and globalization have promoted mosquito-borne diseases' (MBDs) geographic expansion to new areas, such as North African countries, where some of these MBDs were unusual or even unknown. In this review, we summarize the latest data on mosquito vector species distribution and MBDs affecting both human and animals in North Africa, in order to better understand the risks associated with the introduction of new invasive mosquito species such as Aedes albopictus. Currently, 26 mosquito species confirmed as pathogen vectors occur in North Africa, including Aedes (five species), Culex (eight species), Culiseta (one species) and Anopheles (12 species). These 26 species are involved in the circulation of seven MBDs in North Africa, including two parasitic infections (malaria and filariasis) and five viral infections (WNV, RVF, DENV, SINV and USUV). No bacterial diseases have been reported so far in this area. This review may guide research studies to fill the data gaps, as well as helping with developing effective vector surveillance and controlling strategies by concerned institutions in different involved countries, leading to cooperative and coordinate vector control measures.

Nationwide molecular survey of Dirofilaria immitis and Dirofilaria repens in companion dogs and cats, United States of America

Background

Heartworms, Dirofilaria immitis, are known to be widespread in dogs and cats in the USA, but there have been no country-wide prevalence studies performed to date. There have also been no large-scale studies to determine whether the closely related species, Dirofilaria repens, occurs in the USA.

Methods

To provide this large-scale data, we examined whole blood samples (n = 2334) submitted from around the USA to the Molecular Diagnostic Laboratory at Auburn University between 2016 and 2022. Quantitative PCRs for D. immitis (targeting 16S rRNA) and D. repens (targeting cytochrome c oxidase subunit 1 gene) were performed to determine the presence of Dirofilaria DNA. DNA sequencing was performed to confirm the results.

Results

Dirofilaria immitis DNA was found in 6.3% (68/1080) of the dogs from 17/39 states, and 0.3% (4/1254) of the cats from 4/42 states. None of the dogs or cats were positive for D. repens. The average 16S rRNA copy number of D. immitis in the dogs was 1,809,604 in 200 µl whole blood, while only a single copy was found in each of the four D. immitis-positive cats. The prevalence of D. immitis in dogs of different ages, sexes, and breeds did not differ significantly, but the prevalence in Southern states (7.5%, 60/803) was significantly higher than in the Western (1.7%, 1/58), Midwest (3.3%, 4/120), and Northeastern states (3.1%, 3/98) (P < 0.05). Dogs positive for D. immitis were identified in each study year (2016: 4.2%, 2/48; 2017: 9.8%, 4/41; 2018: 5.1%, 8/156; 2019: 4.9%, 15/306; 2020: 9.8%, 26/265; 2021: 4.9%, 13/264). Interestingly, dogs infected with Hepatozoon spp. (11.8%, 37/313) were significantly more likely to also be positive for D. immitis than dogs without evidence of Hepatozoon infection (3.9%, 30/760) (P < 0.0001).

Conclusions

To our knowledge, this is the first nationwide molecular survey of Dirofilaria spp. in dogs and cats in the USA, and the largest molecular survey of canine and feline dirofilariosis worldwide. Further studies are warranted to combine PCR with standard heartworm diagnostics to better understand the prevalence of Dirofilaria spp. and aid in determining the risks posed to dogs and cats in the USA.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05459-5.

Characterization of the genetics and epidemiology of Brugia sp. in domestic dogs in Chad, Africa

Neglected tropical diseases pose a threat to domestic animal health, as domestic animals can serve as reservoirs for certain zoonotic parasitic infections, including Guinea worm (Dracunculus medinensis) and lymphatic filariasis. Surveillance for these parasites in domestic animals is needed to understand infection prevalence and transmission cycles, with the goal of instituting appropriate interventions. The goal of this research was to report our finding of Brugia sp. infection in dogs from Chad, Africa, and to characterize the genetics and epidemiology of the parasite. During a recent Chadian canine pathogen surveillance project, we identified Brugia sp. infections in a total of 46 out of 428 dogs (10.7%) sampled at three time points in 2019-2020. We found high levels of sequence similarity to B. malayi and B. pahangi based on amplification of 18S rRNA, 5.8S rRNA, and ITS-2 regions. Phylogenetic analysis of 18S rRNA gene sequences placed the Chadian Brugia sp. in a clade with other Brugia spp. but grouped it separately from both B. malayi and B. pahangi. Analysis of Hha I sequences showed the greatest similarity with B. patei, a parasite previously reported from dogs, cats, and wildlife hosts in Kenya. Epidemiologic analysis using generalized linear regression modeling found significantly higher odds of Brugia sp. detection among dogs in villages in southern Chad compared to those in the northern region. Further, within the northern region, there were higher odds of detection in the dry season, compared to the wet season, which is consistent with the ecology of a presumably mosquito-borne parasite. The same 428 dogs were tested for Dirofilaria immitis antigen using a commercial assay (IDEXX SNAP 4Dx) at the earliest time point of the study, with 119 dogs testing positive. However, no association was noted between Brugia infection and a dog being positive for Di. immitis antigen, with only seven of the 119 Di. immitis antigen-positive dogs being Brugia-positive. This is the first report of Brugia sp. in domestic dogs in Chad and additional research is needed to definitively identify the species present, elucidate transmission, and understand potential risks to canine and human health.

Seroprevalence and associated risk factors for vector-borne pathogens in dogs from Egypt

Background

Dogs play an important role as reservoirs of many zoonotic vector-borne pathogens worldwide, yet reports of canine vector-borne diseases (CVBDs) in Egypt are scarce.

Methods

Serum samples were collected from pet dogs (n = 500) of the three most common breeds (German Shepherd, Rottweiler and Pit Bull) in five Governates of Cairo (n = 230), Giza (n = 110), Al-Qalyubia (n = 60), Al-Gharbia (n = 60) and Kafr El-Sheikh (n = 40) with a hot desert climate. The presence of antibodies to Anaplasma spp. (A. phagocytophilum, A. platys), Ehrlichia spp. (E. canis, E. chaffeensis, E. ewingii), Borrelia burgdorferi (s.l.) and Dirofilaria immitis were assessed using IDEXX SNAP^® 4Dx^® ELISA tests. For each pathogen, risk factors (i.e. geographical area, keeping condition, sex, age, breed, tick infestation, weekly sanitation of dog enclosures and application of ectoparasiticides) were evaluated by logistic regression approach.

Results

In total, 18.2% (n = 91, 95% CI 15.1–21.8) of dogs scored seropositive for at least one pathogen, the most frequent being Ehrlichia spp. (n = 56; 11.2%; 95% CI 8.7–14.3) followed by Anaplasma spp. (n = 33; 6.6%, 95% CI 4.7–9.1), Borrelia burgdorferi (s.l.) (n = 9; 1.8%, 95% CI 0.9–3.4) and D. immitis (n = 7; 1.4%, 95% CI 0.9–2.9). In the tested population, 15.4% (95% CI 12.5–18.8) of dogs were exposed to a single pathogen while 2.4 (95% CI 1.4–4.2) and 0.4% (95% CI 0.1–1.4) were simultaneously exposed to two or three pathogens, respectively. Major risk factors associated with VBDs were living outdoors (Anaplasma spp., P = 0.0001; Ehrlichia spp., P = 0.0001), female sex (Ehrlichia spp., P = 0.005), German Shepherd breed (Anaplasma spp., P = 0.04; Ehrlichia spp., P = 0.03), tick infestation (Anaplasma spp., P = 0.0001; Ehrlichia spp., P = 0.0001; B. burgdorferi (s.l.), P = 0.003; D. immitis, P = 0.02), irregular sanitation (Anaplasma spp., P = 0.0001; Ehrlichia spp., P = 0.0001; B. burgdorferi (s.l.), P = 0.002; D. immitis, P = 0.01) and not using ectoparasiticides (Anaplasma spp., P = 0.0001; Ehrlichia spp., P = 0.0001; B. burgdorferi (s.l.), P = 0.007).

Conclusion

To our knowledge, this is the first large-scale seroepidemiological study of CVBDs in Egypt. Considering that all of the detected pathogens are potentially zoonotic, effective ectoparasite control strategies, regular examination of pet dogs and successful chemoprophylaxis are advocated.

First Molecular Detection of Dirofilaria immitis and D. repens in Dogs from Kyrgyzstan

BACKGROUND

Dirofilaria immitis and Dirofilaria repens are the causative agents of cardiopulmonary and subcutaneous dirofilariosis, respectively. This neglected disease mainly seen in dogs, cats and wild carnivores is re-emerging recent years. No study was conducted on dirofilariosis in dogs in Kyrgyzstan.

PURPOSE

The goal of this study was to investigate Dirofilaria species using PCR and sequencing in dogs from Kyrgyzstan.

METHOD

Dirofilaria spp. infection in dogs was screened via convential PCR and sequencing in 337 dogs from Kyrgyzstan.

RESULT

The overall prevalence of Dirofilaria spp. was 0.59% (2/337): DNA of D. immitis was detected in one sample and DNA of D. repens in second positive sample. In second sample, parallel co-infection of D. repens with Wolbachia was also found. While D. immitis sequence showed 98.70-100% similarity with previously reported sequences of D. immitis from dog blood, D. repens shared 100% identity with other sequences of D. repens.

CONCLUSION

These results provided first evidence for Dirofilaria spp. in Kyrgyzstan and emphasized the veterinary and medical importance.

The global status of Dirofilaria immitis in dogs: a systematic review and meta-analysis based on published articles

Dirofilaria immitis is a parasitic filarial nematode responsible for heartworm disease in domestic as well as wild canines and felines and pulmonary or cutaneous infections in humans. This systematic review and meta-analysis aimed to evaluate the status of D. immitis in dogs based on available literature. Four English language databases (ISI Web of Science, Scopus, PubMed and Science Direct) containing data on D. immitis prevalence in dogs were thoroughly searched resulting in the inclusion of 193 studies. The findings revealed that the pooled and weighted prevalence of D. immitis infection in dog population based on published papers throughout the world was 10.91% (95% CI=10.18-11.65). In addition, subgroup analysis based on meta-regression revealed that a significant difference between the pooled and weighted prevalence of D. immitis in dogs and country (β =0.14, P=0.049). Given the relatively high prevalence of D. immitis infection in dogs and its adverse effects, it is suggested that to perform more research on the prevention and control of dirofilariasis infection in dogs worldwide.

Filarial worms: a systematic review and meta-analysis of diversity in animals from Iran with emphasis on human cases

Current systematic review and meta-analysis demonstrate the prevalence reports of filariasis in animals in Iran along with human cases. Studies were screened, relevant papers were selected and the random-effect model was used by forest plot with 95% confidence interval (CI). Of 17 records of human case-reports, particularly from Khuzestan province (5 cases), Dirofilaria repens was the most detected parasite (10 cases) with higher involvement of the right eye (7 cases) than other organs. Eleven animal species were reported to be parasitised by filarioids in Iran. The prevalence of Dirofilaria immitis in canids was 14.69% (95% CI: 10.33-19.67), with highest rates (20.92%; 95% CI: 13.84-29.03) in free-ranging dogs. Male (10.07%; 95% CI: 5.10-16.47) and more than 1-year old (20.77%; 95% CI: 8.66-36.42) dogs were more likely to be found infected. The frequency of other filarioids of zoonotic interest was: Acanthocheilonema reconditum in dogs 2.15% (95% CI: 0.71-4.33), Dipetalonema evansi in camels 10.16% (95% CI: 4.73-17.34), Onchocerca cervicalis in horses 3.63% (95% CI: 1.44-6.75%) and Onchocerca fasciata 16.57% (95% CI: 10.12-24.24%) in camels. Still, our knowledge on parasitic filariae in Iran is limited and more investigation is needed in both human and animal populations.

The prevalence of Dirofilaria immitis and D. repens in the Old World

Dirofilaria immitis and D. repens are endemic throughout Europe and southern eastern regions of Asia and reported with increasing frequency in Africa. Nevertheless, the increased awareness of veterinary practitioners, even in countries where the prevalence is low, has led to a decrease D. immitis prevalence in dogs, especially in previously endemic/hyper-endemic areas. Prevalence has significantly increased, however, in areas where heartworm has apparently spread more recently, such as Central and North Eastern Europe. Furthermore, autochthonous cases have been observed in Siberia. Low seroprevalence has been reported in Croatia, while in Romania it has reached 14%. In Greece, the prevalence ranges between 0.7% and 25% whilst in Turkey is 0-18%. Data for canine dirofilariosis in Africa is scarce, and most are case reports. Overall, the dominant species is Achanthocheilonema dracunculoides, although both D. immitis and D. repens have been reported from some countries. In the Far East, the prevalence ranges from 2% to 15% in northeastern of China. In Hong Kong a novel species has been found in dogs and humans (Candidatus Dirofilaria hongkongensis). In India, the prevalence ranges from 4.7%-29.5% in Northeastern states. The main factors that have influenced the spreading of Dirofilaria infections are the climate changes and the introduction of new, invasive, competent mosquito species such as Aedes albopictus and Ae. koreicus. Other factors include relocation and insufficient prevention in dogs, manly in the new areas of colonization. Feline heartworm infection has been diagnosed in every European country when diagnosed either by the Knott test or by serology for circulating antibodies and antigens of the parasite. However, prevalence is much lower than in dogs. In spite of the continuing spreading of heartworm infection, D. repens is the main concern in Europe, mostly for physicians, while the infection is nearly always asymptomatic in dogs. The infection is spreading from Portugal to the Southeastern regions of Finland and Siberia, and in some areas its prevalence overlaps that of D. immitis. Many reasons make more difficult the control of D. repens than D. immitis: the frequent lack of clinical symptoms of suspicion, the specific diagnosis being possible only by blood examination and the inefficacy of some macrocyclic lactones.

Vector-borne nematode diseases in pets and humans in the Mediterranean Basin: An update

Vector-borne diseases (VBDs) are among the leading causes of morbidity and mortality in humans and animals. The scale of VBDs is increasing worldwide, including in the Mediterranean Basin, a region exposed to climate changes. Indeed, weather conditions may influence the abundance and distribution of vectors. The vector-borne nematode diseases of dogs and cats, such as dirofilariosis, onchocercosis, thelaziosis, Cercopithifilaria, and Acanthocheilonema infections, are some of these vectorized diseases, several of which are zoonoses. They are all caused by parasitic nematodes transmitted by arthropods, including mosquitoes (Dirofilaria spp.), black flies (Onchocerca lupi), drosophilids (Thelazia callipaeda), ticks (Acanthocheilonema dracunculoides and Cercopithifilaria bainae), and fleas and lice (Acanthocheilonema reconditum). The control and prevention of these infections and diseases require a multidisciplinary approach based on strengthening collaboration between the different actors in the fields of health, research, sociology, economics, governments and citizens, to improve human, animal, and ecosystem health. This is the concept of "one health." The review aimed to provide a general update on the spatial and temporal distribution of vector-borne nematodes diseases affecting companion animals and humans, as well as the vectors involved in the Mediterranean area. Simultaneously, certain epidemiological parameters, diagnosis, treatment, and control of these diseases based on the "one health" concept will also be discussed.

Filarial infections in dogs in Cyprus, an apparently heartworm free island

The current study investigated for the first time the occurrence of filarial infections in dogs in Cyprus. Blood samples of dogs from five districts of Cyprus (Lefkosia, Lemessos, Larnaka, Pafos and Ammochostos) were examined by the modified Knott's method and by serology, and the morphological classification of microfilariae was confirmed by molecular methods. A total of 200 dogs, 153 living in shelters and 47 owned dogs, were included in the study. Acanthocheilonema reconditum microfilariae were found in 9 (4.5%) samples and one (0.5%) sample was seropositive for D. immitis. No statistical significance was observed between microfilaraemic samples and the evaluated variables apart from the district (p = .005). The present study showed that dogs in Cyprus can be infected with blood circulating microfilariae and for the first time A. reconditum was reported as autochthonous infection in dogs in the country. No microfilariae of Dirofilaria spp. were detected. However, veterinarians should remain vigilant regarding Dirofilaria infections and should consider preventive protection to the animals, at least in case of travel in enzootic areas.

Recent advances on Dirofilaria repens in dogs and humans in Europe

Dirofilaria repens is a nematode affecting domestic and wild canids, transmitted by several species of mosquitoes. It usually causes a non-pathogenic subcutaneous infection in dogs and is the principal agent of human dirofilariosis in the Old World. In the last decades, D. repens has increased in prevalence in areas where it has already been reported and its distribution range has expanded into new areas of Europe, representing a paradigmatic example of an emergent pathogen. Despite its emergence and zoonotic impact, D. repens has received less attention by scientists compared to Dirofilaria immitis. In this review we report the recent advances of D. repens infection in dogs and humans, and transmission by vectors, and discuss possible factors that influence the spread and increase of this zoonotic parasite in Europe. There is evidence that D. repens has spread faster than D. immitis from the endemic areas of southern Europe to northern Europe. Climate change affecting mosquito vectors and the facilitation of pet travel seem to have contributed to this expansion; however, in the authors' opinion, the major factor is likely the rate of undiagnosed dogs continuing to perpetuate the life-cycle of D. repens. Many infected dogs remain undetected due to the subclinical nature of the disease, the lack of rapid and reliable diagnostic tools and the poor knowledge and still low awareness of D. repens in non-endemic areas. Improved diagnostic tools are warranted to bring D. repens diagnosis to the state of D. immitis diagnosis, as well as improved screening of imported dogs and promotion of preventative measures among veterinarians and dog owners. For vector-borne diseases involving pets, veterinarians play a significant role in prevention and should be more aware of their responsibility in reducing the impact of the zoonotic agents. In addition, they should enhance multisectorial collaboration with medical entomologists and the public health experts, under the concept and the actions of One Health-One Medicine.

Does co-infection with vector-borne pathogens play a role in clinical canine leishmaniosis?

BACKGROUND

The severity of canine leishmaniosis (CanL) due to Leishmania infantum might be affected by other vector-borne organisms that mimic its clinical signs and clinicopathological abnormalities. The aim of this study was to determine co-infections with other vector-borne pathogens based on serological and molecular techniques in dogs with clinical leishmaniosis living in Spain and to associate them with clinical signs and clinicopathological abnormalities as well as disease severity.

METHODS

Sixty-one dogs with clinical leishmaniosis and 16 apparently healthy dogs were tested for Rickettsia conorii, Ehrlichia canis, Anaplasma phagocytophilum and Bartonella henselae antigens by the immunofluorescence antibody test (IFAT) and for E. canis, Anaplasma spp., Hepatozoon spp., Babesia spp. and filarioid DNA by polymerase chain reaction (PCR).

RESULTS

Among the dogs examined by IFAT, the seroprevalences were: 69% for R. conorii, 57% for E. canis, 44% for A. phagocytophilum and 37% for B. henselae; while the prevalences found by PCR were: 8% for Ehrlichia/Anaplasma, 3% for Anaplasma platys and 1% for H. canis. No other pathogen DNA was detected. Statistical association was found between dogs with clinical leishmaniosis and seroreactivity to R. conorii antigen (Fisher's exact test: P = 0.025, OR = 4.1, 95% CI = 1-17) and A. phagocytophilum antigen (Fisher's exact test: P = 0.002, OR = 14.3, 95% CI = 2-626) and being positive to more than one serological or molecular tests (co-infections) (Mann-Whitney test: U = 243, Z = -2.6, n ₁  = 14, n ₂  = 61, P = 0.01) when compared with healthy dogs. Interestingly, a statistical association was found between the presence of R. conorii, E. canis, A. phagocytophilum and B. henselae antibodies in sick dogs and some clinicopathological abnormalities such as albumin and albumin/globulin ratio decrease and increase in serum globulins. Furthermore, seroreactivity with A. phagocytophilum antigens was statistically associated with CanL clinical stages III and IV.

CONCLUSIONS

This study demonstrates that dogs with clinical leishmaniosis from Catalonia (Spain) have a higher rate of co-infections with other vector-borne pathogens when compared with healthy controls. Furthermore, positivity to some vector-borne pathogens was associated with more marked clinicopathological abnormalities as well as disease severity with CanL.

The Complexity of Zoonotic Filariasis Episystem and Its Consequences: A Multidisciplinary View

Vector-borne transmitted helminthic zoonosis affects the health and economy of both developing and developed countries. The concept of episystem includes the set of biological, environmental, and epidemiological elements of these diseases in defined geographic and temporal scales. Dirofilariasis caused by different species of the genus Dirofilaria is a disease affecting domestic and wild canines and felines and man, transmitted by different species of culicid mosquitoes. This complexity is increased because Dirofilaria species harbor intracellular symbiont Wolbachia bacteriae, which play a key role in the embryogenesis and development of dirofilariae and in the inflammatory pathology of the disease. In addition, the vector transmission makes the dirofilariasis susceptible to the influence of the climate and its variations. The present review addresses the analysis of dirofilariasis from the point of view of the episystem, analyzing the complex network of interactions established between biological components, climate, and factors related to human activity, as well as the different problems they pose. The progress of knowledge on human and animal dirofilariasis is largely due to the multidisciplinary approach. Nevertheless, different aspects of the disease need to continue being investigated and cooperation between countries and specialists involved should be intensified.