Immitis Infection Research Articles

Radiological Evaluation of Vascular Structures in Cats Infected with Immature Worms of Dirofilaria immitis.

This study aimed to assess thoracic radiographic abnormalities in cats infected with immature stages of Dirofilaria immitis to evaluate the utility of this diagnostic technique during early infection. A total of 123 cats from a hyperendemic area were classified into three groups: asymptomatic cats seronegative to anti-D.-immitis antibodies (Group A), seropositive asymptomatic cats (Group B), and seropositive cats with clinical signs that were at high risk of heartworm-associated respiratory disease (HARD) (Group C). Radiographic measurements and lung parenchymal abnormalities were analyzed and compared across the groups. Significant differences in several parameters, including CrPA/R4, and CdPA/R9 ratios, were observed between healthy and seropositive cats, suggesting early arterial damage even in the absence of adult worms. Other parameters that showed differences between healthy and infected cats were CVC/Ao and CVC/R4 ratios, but not the VHS. Group C exhibited a marked bronchointerstitial pattern, indicating severe parenchymal alterations associated with clinical signs. The study demonstrated that thoracic radiography can detect early vascular and parenchymal changes in feline D. immitis infections, providing valuable information for diagnosing HARD. However, it also highlights the limitations of radiographic techniques, as some seropositive cats displayed no significant abnormalities. The findings underscore the importance of combining radiography with clinical and serological assessments for a more accurate diagnosis of feline heartworm disease.

Wolbachia infection in Aedes aegypti does not affect its vectorial capacity for Dirofilaria immitis.

Mosquito-borne diseases such as dengue and filariasis are a growing public health concern in endemic countries. Biological approaches, such as the trans-infection of Wolbachia pipientis in mosquitoes, are an alternative vector control strategy, especially for arthropod-borne viruses such as dengue. In the present study, the effect of Wolbachia (wMel strain) on the vectorial capacity of Aedes aegypti for Dirofilaria immitis was studied. Our results showed that Wolbachia does not affect the phenotype of mosquito survival or the prevalence, number, and molting rate of third-stage larvae in both susceptible and resistant strains of Ae. aegypti. RNA-seq analysis of Malpighian tubules at 2days post-infection with D. immitis showed the differentially expressed genes (DEGs) with and without wMel infection. No characteristic immune-related gene expression patterns were observed among the DEGs. No significant change in the amount of Wolbachia was observed in the Ae. aegypti after D. immitis infection. Our results suggest that infection of D. immitis in Ae. aegypti populations will not interfere with Wolbachia-based vector control strategies in dengue-endemic areas where cases of D. immitis are present. This study demonstrated the veterinary medical validity of a dengue control program using Wolbachia.

Heartworm (Dirofilaria immitis) Prevalence in Dogs Determined by In-House ELISA Based on Filaria-Specific Antibodies in Tropical and Temperate Regions of Mexico

Dirofilaria immitis is a mosquito-borne nematode of dogs, other carnivores and, occasionally, humans. Globally, D. immitis infection (which causes heartworm) is typically more prevalent in tropical than temperate regions. In this study, the seroprevalence of D. immitis was determined from a sample of 335 non-stray dogs from four municipalities, two each from the states of Puebla and Guerrero in Mexico, using polyclonal antibodies to detect serum antigens using an enzyme-linked immunosorbent assay (ELISA). The accuracy of the assay was compared with the modified Knott’s test. The polyclonal antibody used in the direct ELISA had a high sensitivity (100%) with variable specificity (98.2–98.8%) in the municipalities of Puebla and Guerrero. The area under the curve for the four municipalities was 1.0, indicating a high accuracy test, with a cut-off value ranging from 0.45 to 0.50. The overall prevalence of D. immitis infection was 17.56% (59 out of 335). The highest prevalence was in Acapulco (24.78%), followed by Chilpancingo (20.93%), Tecamachalco (10.81%) and Quecholac (8.06%). The highest percentage of positive samples was detected in tropical regions (23.12%) and the lowest in temperate regions (9.56%). This study demonstrates that polyclonal anti-D. immitis antibodies can successfully diagnose heartworm-infected dogs and be used to monitor prevalence effectively and develop prevention strategies against Dirofilaria infection.

Prevalence, spatial distribution and risk mapping of Dirofilaria immitis in wild canids in southern Québec, Canada

Domestic dogs (Canis familiaris) and wild canids, including coyotes (Canis latrans) and red foxes (Vulpes vulpes), serve as definitive hosts for Dirofilaria immitis, a parasitic nematode causing the heartworm disease. Understanding infection risks in wildlife reservoirs in relation to environmental factors is crucial for assessing exposure risk in domestic dogs. The regional prevalence of D. immitis infection was estimated in trapped wild coyotes and red foxes across Québec, Canada. Spatial clusters of infection were detected using Kulldorff's spatial scan statistics. A series of logistic regression models predicting the D. immitis status in coyotes were built from heartworm development unit (HDU) estimates and cumulative precipitation variables over various time periods. Between October 2020 and March 2021, 421 coyotes and 284 red foxes were examined for the presence of D. immitis. The parasite was found in 43 coyotes and 1 red fox. A high-risk infection cluster was detected in coyotes in southwestern Québec. The best model included as sole predictor the average cumulative HDU contributing to risk of D. immitis in the three years preceding coyote capture. This model significantly predicted infection status with an area under the curve of 76.1%. The cumulative precipitation had no notable effect in any model. This study highlights a high prevalence of D. immitis in coyotes in Québec with regional differences correlated to temperature-derived predictors. The spatial risk of infection in this population likely represents the environmental risk of exposure to the parasite given that coyotes do not receive preventive treatment compared to domestic dogs. Our findings are important for veterinarians in the application of prevention strategies for heartworm disease in domestic dogs.

Loop-mediated isothermal amplification polymerase chain reaction in place of a modified Knott test in screening dogs for heartworm (Dirofilaria immitis) infection combined with antigen detection test.

To improve the current recommendations for the diagnosis of canine heartworm (Dirofilaria immitis) disease. Blood samples collected from 35 shelter dogs in the Republic of Korea. Samples were tested for the presence of microfilaria using the modified Knott (MK) test and D immitis DNA using species-specific loop-mediated isothermal amplification (LAMP) PCR. The blood samples were additionally assessed for the presence of heartworm antigens using the Antigen Rapid Canine Heartworm AG Test Kit 2.0 (Bionote Co). The performance of the MK test and LAMP PCR was assessed through statistical analysis, with a paired McNemar test utilized for comparison. The heartworm antigen was detected in 28.5% of the subjects. Of the 10 positive animals, the MK test detected microfilaria in 4 of 35 (11.4%) animals, and LAMP PCR detected D immitis DNA in 6 of 35 (17.1%). The results of this study indicate that the LAMP PCR showed more positive results in samples compared to the conventional MK test. The D immitis-specific LAMP PCR assay has the potential to function as an alternative to current detection methods. It could complement the existing antigen detection tests in diagnosing canine heartworm infections.

Evaluation of Seroprevalence and Risk Factors of Heartworm Infection for Dogs in Rio de Janeiro with Access to Veterinary Care

Heartworm infection is a chronic disease with clinical signs and effects ranging from an asymptomatic condition to severe disease and death. The prevalence of heartworm disease in the state of Rio de Janeiro has been reported to be high (21.3%). The present study was conducted to evaluate the seroprevalence and risk factors of heartworm infection for the canine population with access to veterinary services in different areas of the state of Rio de Janeiro, Brazil. A total of 1787 canine blood samples were obtained from 135 practices across 8 different areas of Rio de Janeiro state (Rio de Janeiro municipality, São Gonçalo municipality, Niterói municipality, Baixada Fluminense, and the northern, southern, eastern, and mountainous areas) and tested for the presence of Dirofilaria immitis antigens and antibodies against several tick-borne disease pathogens using a commercial immunochromatography technique (Vetscan® Flex 4 Rapid Test; Zoetis; NJ USA). Pet owners reported living conditions, physical characteristics, demographics, and clinical signs for evaluation of risk factors for heartworm infection. Only two evaluated risk factors were shown to enhance the risk for D. immitis infection, including having a short hair coat vs. having a medium or long hair coat (OR 2.62) or positive for antibodies to tick-borne disease parasites (OR 3.83). Clinical signs reported for dogs with heartworm disease were typical for that condition. The overall prevalence of heartworm disease in the state was 8.2%, ranging from 2.4% in the mountainous region to 29.4% in the eastern area. It could not be determined if veterinarians were not diligent about dispensing heartworm preventatives or if poor levels of compliance by dog owners were responsible for higher infection rates in some areas of the state.

Beyond Borders: Dirofilaria immitis Infection in Dogs Spreads to Previously Non-Enzootic Areas in Greece-A Serological Survey.

Although Dirofilaria immitis in dogs is considered enzootic in northern Greece, the available data on the occurrence of infection in southern parts of the country demonstrate its scarcity. The aim of this study was to update the current knowledge on D. immitis infection in dogs in areas of Greece previously considered non-enzootic (Central Greece, Attica, Peloponnese, North Aegean, South Aegean, Crete and the Ionian islands). In total, 1528 dog blood samples were collected from the aforementioned areas and examined by Dirochek® ELISA (Synbiotics). Additionally, data published until 2022 on the prevalence of infection in these areas were compared to the data of this study. The 'Wilson' Score interval method (Epitools) was employed. Overall, 10.8% of dogs were positive for D. immitis. In detail, the prevalence was 21.7, 13.7, 10.7, 5.4, 4.7, 6.2 and 17.0% for D. immitis, in Central Greece, Attica, Peloponnese, North Aegean, South Aegean, Crete and the Ionian islands, respectively. Infection with D. immitis is recorded for the first time in Crete. The probability of a dog becoming infected has increased 4.1 times since 2022 in previously non-enzootic areas. This study denotes the spread of D. immitis and highlights the necessity for preventive measures.

Epidemiological analysis of Dirofilaria immitis (Spirurida: Onchocercidae) infecting pet dogs (Canis lupus familiaris, Linnaeus, 1758) in Baixada Fluminense, Rio de Janeiro.

Dirofilaria immitis infection is routinely detected in dogs during veterinary care in tropical and subtropical regions worldwide. Parasitological tests for the detection of this infection are routinely performed only in areas with a high prevalence. Baixada Fluminense, a region in Rio de Janeiro, was considered heartworm-free until local veterinarians began to receive blood exams results indicating the presence of microfilariae (MF). A laboratory database was hence used to collect data from 2017 to 2020 to understand the extent of spread of the parasite in this area. The results of complete blood count analysis and MF or heartworm antigen detection tests conducted on canine samples sent from veterinary clinics in Baixada Fluminense (Magé, Duque de Caxias, Guapimirim, Nova Iguaçu, and São João de Meriti municipalities) were included. In total, the results of 16,314 hematological tests were considered. The overall prevalence of D. immitis was 3.4% (554/16,314), considering that only one test result was obtained per animal on the same day. This study is highly relevant because it indicates the spreading geographic distribution of the worms, heightens awareness among local health professionals and the general population, and encourages compliance with prophylactic measures to prevent further spread of parasite.

Microfilaremic infection in canine filariosis in Colombia: a challenge in morphological and molecular diagnostics.

Canine filariosis is caused by filiform nematodes and affects several species of animals as well as humans. The disease produces a wide range of symptoms that can often be confused with other diseases, which increases the complexity of its diagnosis. The search for methodologies to facilitate its diagnosis is a challenge, and specific and differential identification of the parasite species causing the disease holds key to a successful diagnosis. In Colombia, there is a problem of underdiagnosis of filariosis in microfilaremic dogs infected by Dirofilaria immitis and Acanthocheilonema reconditum, and of microfilaremias not related to heartworm disease. The highest prevalences have been reported for D. immitis infections, although new cases of A. reconditum infections are beginning to appear. The aim of this study was to differentiate the microfilariae infections caused by D. immitis and A. reconditum by a morphological and molecular characterization of microfilariae so as to facilitate an accurate diagnosis of canine filariosis in the metropolitan area of Bucaramanga (Colombia). For this purpose, 400 blood samples with anticoagulants were collected from the dogs and analyzed with the help of a commercial immunochromatography kit for the detection of D. immitis circulating antigen. The Woo, Knott, and polymerase chain reaction (PCR) techniques were employed for determining the parasite count, morphological observation, and molecular identification of microfilariae present in the dogs respectively. The prevalence of microfilaremic dogs in Bucaramanga metropolitan area was 18.75% (75/400). The prevalence of dogs that tested positive for D. immitis in the antigen and in PCR tests was 1.25% (5/400) and 1% (4/400), respectively. Furthermore, the PCR test revealed that 17.75% of the microfilaremic dogs tested positive for A. reconditum (71/400) (first report in the metropolitan area of Bucaramanga), with one animal co-infected by both species, and 0% for D. repens (0/400). However, by morphological characterization, 4% of the microfilariae (3/75) corresponded to D. immitis, 20% (15/75) to D. repens, and 76% (57/75) to A. reconditum. The use of molecular diagnostic methods such as PCR aids in the specific identification of the parasite, thus making it a more accurate method than the morphological characterization of microfilariae. The identification of the parasites by PCR helps improve the veterinary diagnosis of canine filariosis in Colombia, which would lead to the establishment of an appropriate treatment protocol for each species of filaria and also to the generation of reliable data to be used at the clinical and epidemiological levels.

Heartworm disease in domestic dogs in Estonia: indication of local circulation of the zoonotic parasite Dirofilaria immitis farther north than previously reported

BackgroundThe mosquito-borne zoonotic parasite Dirofilaria immitis continues to spread northwards in Europe. This parasite can cause potentially life-threatening heartworm disease in dogs and pulmonary dirofilariasis in humans and is, therefore, a major health concern in both the veterinary medicine and human medical fields. This is the first report of D. immitis infections and heartworm disease in the Baltic country Estonia.MethodsData on canine D. immitis infections and heartworm disease were collected from the electronic patient records database of the Small Animal Clinic of Estonian University of Life Sciences, the only university clinic in Estonia. The patient records of dogs with confirmed diagnosis of D. immitis infection or heartworm disease were reviewed and summarised.ResultsSix dogs had been diagnosed with confirmed D. immitis infection or heartworm disease at the university clinic in 2021–2022. The confirmed diagnoses had been reached following international guidelines, based on a combination of different tests. Molecular confirmation of the parasite species had not been performed. Two of the dogs had been imported while four had no travel history outside of the country.ConclusionsFour of the dogs with a confirmed D. immitis infection or heartworm disease had no history of being imported or travelling outside of the country, indicating autochthonous infections and, consequently, local circulation of the parasite in Estonia. These findings represent the new northernmost autochthonous cases of D. immitis infection and canine heartworm disease reported in the European Union.Graphical

Prevalence and risk factors of canine dirofilariasis in Kano metropolis, Kano State Nigeria

Dirofilariasis is a zoonotic disease caused by Dirofilaria immitis causes heartworm disease and invasive human filariasis. This study determined the prevalence and risk factors for the acquisition of canine dirofilariasis in dogs in Kano metropolis, Kano state, Nigeria. Blood samples were collected from 170 dogs of 6 months and above in Kano metropolis and tested by the Modified Knott’s technique for circulating microfilaria, an Enzyme-linked Immunosorbent Assay in order to detect the presence of filarial antigens of D. immitis as evidence of occult infection. A pre-tested, structured questionnaire was administered to each of the dog owner to obtain demographic, management and environmental information associated with each dog sampled. Test for association and hypothesized factors was determined and the its strength was tested using a binary logistic regression. Out of the 170 dogs tested, 17 (10.00%) were positive for D. immitis infection with the Modified Knott’s technique. However, after subjecting the samples for antigen detection by ELISA tests 23 (13.53%) were positive for D. immitis antigen, giving a sero-prevalence of 13.50%. There was agreement between the two tests on the 17 microfilaria positive samples. Majority of the infected dogs were males (56.5%), aged 24-47 months (43.50%) and of local breed (65.2%). There was significant association (p ≤ 0.05) between D. immitis infection and dogs usage, breed and dogs with stagnant water (gutters) close to their houses (OR= (9.714; 95% CI (1.179-80.024)), OR=5.33; 95% CI (1.349-21.079), OR= 5.775; 95% CI (0.697- 47.832),respectively. The study established that D. immitis infection is prevalent (13.53%) in household dogs indicating the possibility of zoonotic transmission in Kano metropolis. This demands for intensified vector control and good dog management practices to reduce dog to dog and dog to human transmission.

Is the European badger a new host for Dirofilaria immitis? The first records in Greece

Dirofilaria immitis is a ubiquitous nematode parasite with zoonotic potential, transmitted by mosquitoes, that causes heartworm disease in various animal species. Dogs are the parasite’s typical final host, and wild carnivores represent the parasite’s reservoir in nature. Studies on D. immitis infections in wild animals are essential to assess infection pressure for domestic animals, and until now, there has been only one infection case reported in a European badger (Meles meles). The current report describes the first two European badger cases with cardiovascular dirofilariosis in Greece. Two adult male badgers were rescued in Heraklion and Chania, Crete Island, and admitted to “ANIMA -Wildlife Rehabilitation Centre” in Athens. The detailed clinical examination revealed that the first badger suffered from severe broncho-pneumonitis while the second one displayed clinical signs associated with severe brain trauma. Blood samples were taken for haematology and biochemistry analyses during their short hospitalisation period. In addition, different routine diagnostic tests were carried out, including heartworm antigen testing (ELISA) and the modified Knott’s test for microfilariae. Both badgers were positive in both tests. The animals died a few hours after their admission and the detailed necropsies followed, revealed the presence of three parasites in each animal’s right heart, morphologically identified as adults of D. immitis. These findings add the European badger in the list of additional potential reservoir hosts for D. immitis and highlight the potential role of wildlife for companion animals and human health.

Development of adult Dirofilaria immitis worms in the Rag2/Il-2rγ-/- mouse model

Dirofilaria immitis is the causative agent for one of the major parasitic infections in dogs. It is currently not possible to reliably diagnose the infection before the development of fertile adult female worms and the presence of microfilariae which takes six to 7 months. However, at this point adult worms already reside in the pulmonary arteries and can cause significant damage. Novel in vivo models may facilitate the development of new diagnostic tools and improve treatment options for both the early and late stages of D. immitis infections. In this paper, we aimed to increase the capabilities of recently published mouse models in which severely immune-deficient mice were shown to be susceptible to D. immitis. Our data shows that D. immitis may grow into fully developed mature male and female worms in C57BL/6 Rag2/Il-2rγ-/- mice with comparable growth rates to the natural canine host. The adult worms of D. immitis were shown to migrate into body cavities as well as the heart in this model. However, the presence of adult worms inside the heart of infected mice led to the development of caval syndrome in 36% of infected mice after five to 6 months. Overall, the current study complements recently published efforts to establish a D. immitis mouse model by extending the development of D. immitis into mature adult stages and will facilitate further preclinical research.

Dirofilaria immitis in dogs from the coastal tourist region of the state of Alagoas, Brazil.

Canine dirofilariasis, caused by Dirofilaria immitis, is prevalent worldwide. However, the frequency of canine infection in the state of Alagoas, Brazil is scarcely unknown. This study aimed to evaluate the frequency of D. immitis infection in dogs from the coastal municipalities of Alagoas and analyze the risk factors associated with the infection. A cross-sectional study was performed using 426 dogs of different breeds and sex distributed across 15 coastal municipalities in the state of Alagoas. Blood samples were collected from each dog and analyzed for circulating microfilariae and free D. immitis antigens. To investigate the risk factors associated with D. immitis infection, we collected information on dog environments using an epidemiological questionnaire. The results revealed that 12.7% of dogs tested positive for D. immitis. Dogs with travel history were 3.52 times more likely to be infected. Thus, infected dogs in the coastal region of Alagoas should be regularly monitored and the public health system should plan strategies to control this zoonotic disease.

Prevention of heartworm infection in dogs using a combination of moxidectin, imidacloprid and praziquantel: evidence from a randomized clinical trial.

The aim of this study was to evaluate the efficacy of a topical combination of moxidectin 3.5%, imidacloprid 10% and praziquantel 10% for the prevention of Dirofilaria immitis (Leidy, 1856) infection in dogs. For this purpose, a randomized and controlled clinical trial was conducted between August 2021 and October 2022, in the municipality of Goiana, state of Pernambuco, north-eastern Brazil, where heartworm is highly prevalent. Of the 213 dogs initially sampled (baseline), 68 (31.9%) were positive for adult antigens (SNAP 4Dx Plus, Idexx) and/or microfilariae (modified Knott's test). On day 0, 140 negative dogs were randomly included in the treatment and control groups, 70 animals each. During the study, 60 dogs (34 treated and 26 untreated) were removed for different reasons. At the end of the study (day 360 ± 2), 36 treated and 44 untreated were sampled and included in the efficacy calculation. The efficacy against the development of adults and microfilariae was 84.7%, with only one treated dog being positive for adult antigens but negative for microfilariae. On the other hand, eight untreated dogs were positive for adultantigens and/or microfilariae, resulting in a significant difference in the number of positives between groups (Chi-square test = 4.706, df = 1, P = 0.0301). Remarkably, the efficacy against the appearance of D. immitis microfilariae was 100% (i.e., all treated dogs negative) and three untreated dogs were positive for microfilariae. The topical combination of moxidectin 3.5%, imidacloprid 10% and praziquantel 10% significantly reduced the risk of D. immitis infection in treated dogs as compared with untreated dogs, in a highly endemic area in north-eastern Brazil.

Status of selected feline infectious diseases in Gwangju, Korea

From 2008 to 2017, blood samples from 280 and fecal samples from 149 stray cats in Gwangju, South Korea, were examined for feline immunodeficiency virus (FIV), feline leukemia virus (FeLV), Dirofilaria immitis, and Giardia infections using commercial diagnostic tests. Overall, the combined prevalence of FeLV, FIV, D. immitis, and Giardia was 8.6%, 1.4%, 0.4%, and 2.0%, respectively. FeLV exhibited the highest prevalence rate among the 4 pathogens surveyed, both in the 2008–2009 (9.6%) and 2015–2017 (6.3%) surveys. The results of the feline Giardia study represent the first prevalence report of Giardia infection among stray cats in Korea.

Dirofilaria immitis in Italian Cats and the Risk of Exposure by Aedes albopictus.

Background: Dirofilaria immitis, the agent of canine and feline heartworm disease (HWD), is a widespread mosquito-borne helminth. The true prevalence of HW infection in cats is likely underestimated due to the difficulty in establishing a definitive diagnosis. Aedes albopictus, a recognized competent vector for D. immitis, is currently considered the most invasive mosquito species worldwide and Italy presents the highest abundance of Ae. albopictus in Europe. Materials and Methods: The present study was aimed at evaluating the current seroprevalence of D. immitis antibodies in cats in Italy. Further, the ecological niche model (ENM) was applied to evaluate the potential future risk of feline HWD associated with the presence of Ae. albopictus. Results: Sera of 812 Italian cats were analyzed, and the average prevalence of D. immitis antibodies was 12%. Seropositivity was significantly associated with age (<6 years), whereas there was no association with sex or geographical area. Data obtained with the risk map showed that the highest risk of infection was found in northern inland areas and along coastal areas, whereas the lowest risk was identified at higher altitudes. The ENM correctly classified most of the areas where D. immitis seropositive cats were found, with 80.4% occurring in high and very high-risk areas. Conclusions: Results of the present study suggest that cats in Italy are exposed to D. immitis infection, and that routine prevention should be part of the general health care protocols in cats. Moreover, the resulting risk maps indicate that areas with a suitable habitat for Ae. albopictus may put cats at risk of exposure to D. immitis.

Association between vector-borne pathogen seroprevalence in shelter-housed and owned dog populations in the contiguous United States of America

Domestic dogs are susceptible to numerous vector-borne pathogens that are of significant importance for their health. In addition to being of veterinary importance, many of these pathogens are zoonotic and thus may pose a risk to human health. In the USA, owned dogs are commonly screened for exposure to or infection with several canine vector-borne pathogens. Although the screening data are widely available to show areas where infections are being diagnosed, testing of owned dogs is expected to underestimate the actual prevalence in dogs that have no access to veterinary care. The goal of this study was to measure the association between the widely available data from a perceived low-risk population with temporally and spatially collected data from shelter-housed dog populations. These data were then used to extrapolate the prevalence in dogs that generally lack veterinary care. The focus pathogens included Dirofilaria immitis, Ehrlichia spp., Anaplasma spp., and Borrelia burgdorferi. There was a linear association between the prevalence of selected vector-borne pathogens in shelter-housed and owned dog populations and, generally, the data suggested that prevalence of heartworm (D. immitis) infection and seroprevalence of Ehrlichia spp. and B. burgdorferi are higher in shelter-housed dogs, regardless of their location, compared with the owned population. The seroprevalence of Anaplasma spp. was predicted to be higher in areas that have very low to low seroprevalence, but unexpectedly, in areas of higher seroprevalence within the owned population, the seroprevalence was expected to be lower in the shelter-housed dog population. If shelters and veterinarians make decisions to not screen dogs based on the known seroprevalence of the owned group, they are likely underestimating the risk of exposure. This is especially true for heartworm. With this new estimate of the seroprevalence in shelter-housed dogs throughout the USA, shelters and veterinarians can make evidence-based informed decisions on whether testing and screening for these pathogens is appropriate for their local dog population. This work represents an important step in understanding the relationships in the seroprevalences of vector-borne pathogens between shelter-housed and owned dogs, and provides valuable data on the risk of vector-borne diseases in dogs.Graphical abstract

Dirofilaria immitis in pet dogs from the metropolitan area of the Colombian Caribbean

A cross-sectional study was carried out to determine the frequency and factors associated with Dirofilaria immitis infection in pet dogs in the metropolitan area of the Colombian Caribbean (northern Colombia). A total of 173 dogs were analyzed by a commercial rapid immunochromatographic test (RIT) and a nested PCR of the cytochrome oxidase subunit I gene, in parallel. Ninety-two (53.2%) of the dogs showed positive results to the RIT, while 59 (34.1%) animals had D. immitis DNA by PCR. Positivity to one or both diagnostic techniques was detected in 104 (60.1%; CI95%: 53.8–67.4) of the sampled dogs. In PCR-positive dogs, phylogenetic analyses evidenced high nucleotide identity (100%) with sequences previously obtained from mosquitoes, dogs and other mammals in different countries. Exercise intolerance (p = 0.002; OR: 2.33; CI95%: 1.37–3.96) and thrombocytopenia (p = < 0.001; OR: 1.95; CI95%: 1.11–3.43) were the main factors associated with D. immitis infection in dogs. The high frequency of D. immitis in dogs indicates a wide distribution of this parasite in the metropolitan area of the Colombian Caribbean, which can be of animal and public health concern. Our results highlight the need to combine different methods to increase the diagnostic accuracy of D. immitis.

“Slow kill” treatment reduces DNA damage in leukocytes of dogs naturally infected with Dirofilaria immitis

Parasitic diseases are considered to be a cause of oxidative stress which leads to oxidative damage of various molecules including DNA. This can result in mutations, replication errors, and genome instability. Therefore, aim of this study was to measure DNA damage induced by Dirofilaria immitis in the single cells such as dogs’ leukocytes using the comet assay. Also, we monitored the effects of antiparasitic treatment on mitigation of sensitivity to DNA damage in leukocytes treated with H2O2 using the in vivo and ex vivo comet assay. The whole blood samples from 34 dogs from Serbia were used, both males and females, from one to 13 years old, both pure and mixed-breeds. A rapid immunochromatographic test (Antigen Rapid Heartworm Ag 2.0 Test Kit, Bionote, Minnesota, USA) was used for the detection of D. immitis antigens. The modified Knott’s test and PCR were used in the aim of detecting D. immitis microfilariae in dogs’ blood, and evaluating the number of circulating microfilariae during the treatment. The genotoxicity evaluation showed that D. immitis infection resulted in DNA damage in naturally infected dogs, with the highest DNA damage occurring in the group of dogs with severe clinical signs. Treatment with ivermectin and doxycycline decreased DNA damage in leukocytes of dogs in all groups, as the intensity of infection decreased due to applied therapy. Ex vivo comet assay results showed that leukocytes exhibited decreased sensitivity to H2O2-induced DNA damage during treatment. The results of the modified Knott’s test and PCR in our study showed that treatment with ivermectin and doxycycline was successful in decreasing the average number of microfilariae during the time and at the end eliminating them from the dogs’ blood.