Immitis Infection In Dogs Research Articles

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.

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.

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.

Prevalence of canine heartworm infection in Queensland, Australia: comparison of diagnostic methods and investigation of factors associated with reduction in antigen detection

BackgroundThe prevalence of Dirofilaria immitis infection in dogs is increasing globally and spreading into new areas. Prevalence of dirofilariosis in the state of Queensland, Australia, was as high as 90% before the introduction of macrocyclic lactones. Limited research on prevalence of D. immitis infection in dogs in Queensland has been reported in the last 30 years. Antigen testing is the most common method for detection of dirofilariosis but its accuracy is reduced by antigen getting trapped (blocked antigen) in immune complexes (ICs). The objectives of this research were to determine the prevalence of D. immitis infection in dogs from two geographical areas (Brisbane and Townsville) in Queensland, to determine the extent to which blocked antigen affects the validity of antigen testing, and to explore whether this was associated with microfilaraemia, location, age or sex.MethodsBlood samples from Brisbane (sub-tropical climate) and Townsville (tropical climate) shelter dogs were evaluated for the presence of D. immitis antigen before (conventional antigen testing, CAT) and after dissociation of ICs by heat treatment (antigen testing after heat treatment, ATHT), using a commercially available test. Microfilariae were detected using modified Knott’s test (MKT). Test proportions were compared with McNemar’s test and the association between antigen test-discordant results (positive for antigen after dissociation of ICs) and microfilaraemia, location, sex and age was modelled using logistic regression.ResultsDirofilaria immitis prevalence in dogs from Townsville (22% by CAT, 32.1% by ATHT and 16.7% by MKT) was significantly higher than in dogs from Brisbane (1.1% by CAT and MKT and 1.7% by ATHT) (P< 0.001). Dissociation of ICs allowed detection of significantly more D. immitis infected dogs than either conventional antigen testing or microfilariae detection, or the combined antigen and microfilariae detection (P< 0.001). The odds of dogs being positive for antigen after dissociation of ICs were significantly higher for microfilaraemic, 3–4-year-old female dogs from Townsville.ConclusionsThe high prevalence of infection with D. immitis in dogs from Townsville poses a health risk for local susceptible host species, including humans. Dissociation of ICs increases antigen detection and should be considered in dogs suspected of D. immitis infection but negative on routine testing.Graphical

Evaluation of Side Effects and Long-Term Protection of a Sustained-Release Injectable Moxidectin Formulation against Dirofilaria immitis Infection in Dogs: An Observational-In Field Multicentric Study.

Simple SummaryThe sustained-release moxidectin formulation of Afilaria SR is labelled to prevent Dirofilaria immitis infection in dogs for a period of six months. An observational—in field multicentric study was design to evaluate the tolerability and the long-term prevention of Afilaria SR in Italy. A total of 583 dogs were recruited from 2018 to 2021, receiving the drug annually and monitored by veterinary practitioners after each administration. Antigenic tests were performed 210, 365, 730, and 1095 days after the administration of the drug. None of the enrolled dogs was detected as positive, since it was possible to establish that 100% of protection was achieved. Afilaria SR was well tolerated since only the 13% of dogs demonstrated mild reaction in the injection site and only two dogs out of 583 demonstrated anaphylactoid or angioneurotic reactions. These data support the high prevention rate against Dirofilaria immitis disease in all enrolled dogs and indicate the high safety profile of the product, considering the low number and the low grade of side effects.The sustained-release moxidectin formulation Afilaria SR is a relatively new product and has been labelled to prevent Dirofilaria immitis infection in dogs for a six months-period. An observational, in field multicentric study was performed, aiming to evaluate the tolerability and the long-term prevention of Afilaria SR in Italy, a country where filariasis is endemic. The study was designed to include not less than 300 dogs, older than 6 months, of any breed. Side effects were recorded by veterinarians and antigenic tests were performed after 210, 365, 730, and 1095 days after the administration of the drug. A total of 583 dogs were recruited from 2018 to 2021 and all of them were negative with respect to antigenic tests at all time points, indicating that 100% of protection was achieved. Ranking of adverse reactions and correlation to patient features were analyzed using descriptive statistics and χ2 square test, respectively. Afilaria SR was well tolerated: 13% of dogs experienced mild reactions and only two dogs out of 583 (0.3%) demonstrated anaphylactoid/angioneurotic reactions, resolved administering corticosteroids. These data support that Afilaria SR prevented Dirofilaria immitis disease in all enrolled dogs and the low number and the low grade of side effects indicate the high safety profile of the product.

Successful Treatment and Management of Canine Ehrlichiosis-Leishmaniosis-Heartworm Comorbidity

Background: Canine vector borne diseases (CVBD) are common in tropical countries where the climate favors arthropods abundance. Comorbidity with one or more CVBD are reported as clinical complication and worsen prognostic. Canine visceral leishmaniosis (CanL) is an endemic zoonotic disease in Brazil caused by Leishmania infantum, with several restrictions to canine treatment and suggestion of reservoirs euthanasia for disease control. Heart worm (HW) is a helminthic disease caused by Dirofilaria immitis infection in dogs. It is a chronic heart disease, which can lead to death by congestive heart failure. Canine ehrlichiosis (CE) is caused by Ehrlichia canis bacterial infection with a zoonotic potential and fatal to dogs in acute and chronic presentations. Exposed the above, this study aims to describe a successful treatment and management of a dog with CanL, CE, and HW comorbidity. Case: A 3-year-old male uncastrated black Labrador dog, weighing 35 kg, was admitted to the veterinary clinic due to immunochromatographic CanL positive test performed by municipal zoonosis control center active surveillance in August 2014. Clinical exam showed a mild shedding, intermittent eye white/yellow discharge and popliteal lymph nodes enlargement. After positive for CanL, veterinary requested more laboratorial exams. IFAT and ELISA were positive for CanL, blood smear showed presence of microfilaria, and bone marrow cytology showed Ehrlichia spp. morulae and microfilaria. Initial treatment prescribed was oral doxycycline, omeprazole, ranitidine, and domperidone for 30 days, and allopurinol and ivermectin until further recommendation. Additionally, repellent collar, repellent spray and vitamin supplement was indicated. After first month, marbofloxacin for 30 days and three doses of immune stimulant protocol were administrated. After three months of treatment, dog still positive for heartworm, ehrlichiosis, and CanL. Doxycycline protocol was repeated. Dog became consistently negative for all pathogens one year later with persistent thrombocytopenia but without clinical signs, ergo allopurinol and ivermectin were discontinued. After four years of follow up, the animal had an acute pancreatitis and died, with unremarkable total blood count and negative for all pathogens. Discussion: CVBD coinfections are commonly reported as worsen prognostic in endemic regions. The pathogens reported here share a host immunomodulation competence. L. infantum and Ehrlichia spp.downregulates Th1 response, whereas D. immitis increase as Th2 profile. The therapeutic protocol was iniciated by staging CanL. Since the patient had clinical signs, allopurinol was prescribed as a well-established drug for CanL. Marbofloxacin was added due to its high safety drug in clinical improvement of infected dogs with and without renal disease and in vitro effectiveness against L. infantum. Domperidone was used to promote Th1 cytokine profile as INF-γ, IL-2, IL-12, and TNF-α. We used an immunostimulant protocol to favor polarization to the Th1 profile comprised by 30 days of domperidone protocol followed by a vaccine and an immunomodulator. Doxycycline was used successfully for Ehrlichia spp. and HE clearance after two treatment courses and one year of ivermectin every 15 days. The animal presented intermittent coughing episodes on the first treatment course, but no medical intervention was needed besides exercise restriction. Our report shows the successful management of one dog with CanL, CE and HE comorbidity. This success was possible due to early detection and good therapeutic choice.Keywords: canine visceral leishmaniosis, coinfection, Dirofilaria immitis, Erhlichia canis, Leishmania infantum, treatment.

Heartworm prevalence in dogs versus cats: Multiple diagnostic modalities provide new insights

The cornerstones of diagnosis of heartworm (HW) in dogs are the detection of circulating antigen from adult female Dirofilaria immitis or the visualization of microfilariae in whole blood. These tests are less sensitive in cats because of the feline immune response leading to low numbers of adult worms, but heartworm antibody tests are also licensed for use in cats. HW antibodies in cats are detectable when there has at least been larval development in the tissues, but positive antibody tests cannot distinguish between current and previous larval infections; thus, cats with positive antibody test results are considered currently or previously infected with D. immitis. The aim of the present study was to use multiple HW diagnostic modalities to maximize detection of infection in dogs and cats at high risk of infection and to compare infection prevalence between these two hosts. Blood samples collected from 100 stray dogs and 100 stray cats at Florida animal shelters were tested for HW antigen (before and after heat treatment) and microfilariae; cats were also tested for HW antibody. Dogs were significantly (P = 0.0001) more likely to be diagnosed with adult HW infection (28 %; 95 % CI: 20.1–37.6%) when compared with cats (4 %; 95 % CI: 1.6–10.2%) on the basis of positive antigen and microfilariae test results. Cats with current or previous adult, immature adult, or larval HW infections comprised 19 % (95 % CI: 12.4%–27.9%) of the feline population, which was not significantly different (P = 0.1) from the prevalence of adult D. immitis infection in dogs. Testing unprotected cats for heartworm antibodies demonstrated a similar, high risk of infection to the matched unprotected dog population in Florida, which supports the use of HW preventives in cats in areas where HW transmission occurs.

Prevalence and distribution of Dirofilaria immitis infection in wild canids in southern Ontario.

Wild canids represent a potential reservoir host for Dirofilaria immitis infection in dogs in Ontario. Since wild canids are not protected by chemoprophylaxis, understanding the epidemiology of D. immmitis in these populations may help elucidate the background risk of infection for dogs. The aim of this study was to determine the prevalence and distribution of D. immitis infection in wild canids across southern Ontario. From February 2016 to March 2017, 290 wild canid carcasses (273 coyotes and 17 foxes) were collected from across the region and assessed for the presence of D. immitis at the time of necropsy. Overall, D. immitis infection was identified in 4.8% (95% CI 2.8-8.0%) of these wild canid carcasses. Among coyotes, 5.1% (95% CI 3.0-8.5%) were positive; no evidence of D. immitis was found in the 17 foxes. Dirofilaria immitis infections in wild canids were detected in two regions of southern Ontario: 12 of the 14 D. immitis infections were detected in the south-western region and two were detected in the eastern region. Our findings provide preliminary insights into the prevalence and geographical distribution of D. immitis in coyotes and foxes in southern Ontario.

Dirofilaria immitis infection in dogs in Algodoal Island, Brazilian Amazon

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

Prevalence of Dirofilaria immitis Infections in Dogs and Cats in Hainan Island/Province and Three Other Coastal Cities of China Based on Antigen Testing and PCR

Canine and feline heartworm disease caused by Dirofilaria immitis is a serious and sometimes fatal infection transmitted by mosquitos. Little is known about the prevalence or distribution of D. immitis infection in dogs and cats on the island of Hainan island/province or coastal cities of China. The present study examined the occurrence of D. immitis infections in dogs (n = 869) and cats (n = 51) in Hainan island/province and prevalence in dogs from 3 coastal cities (Shenzhen [n = 55], Shanghai [n = 69], and Hangzhou [n = 45]) in southern and eastern China. A commercial antigen detection (AD) test and 2 PCR methods (16S ribosomal RNA and Wolbachia surface protein [ WSP] genes) were used to determine the prevalence of D. immitis from animals >6 mo old with no previous history of D. immitis preventive treatment or heartworm infection. Gene sequencing was used to confirm positive PCR samples. The AD test was not used on cat samples. Using the AD test, the prevalence in dogs was 0.5% (4/869) in Hainan island/province, 0% (0/55) in Shenzhen, 1.5% (1/69) in Shanghai, and 0% (0/45) in Hangzhou. Prevalence by 16S rRNA gene PCR was 7.4% (64/869) of dogs from Hainan island/province, 0% (0/55) in dogs from Shenzhen, 1.5% (1/69) in dogs from Shanghai, and 0% (0/45) in dogs from Hangzhou. Prevalence by WSP gene PCR in dogs was 5.3% (46/869) in Hainan island/province, 0% (0/55) in Shenzhen, 1.5% (1/69) in Shanghai, and 0% (0/45) in Hangzhou. Prevalence in the 51 cats from Hainan island/province was 9.8% and 5.9% by 16S rRNA and WSP gene PCR, respectively. The present study demonstrates that canine heartworm exposure occurs in dogs and cats in Hainan island/province and that PCR methods detected a higher prevalence than did the AD method. The 16S rRNA gene PCR detected more positive samples than did the WSP gene PCR in both dogs and cats. The 3 coastal cities had very few dogs that had evidence of D. immitis exposure.

Further Characterization of Molecular Markers in Canine Dirofilaria immitis Infection.

Dirofilaria immitis is a common filarial parasite found in dogs and cats in the Americas, with the pathophysiological consequences of the infection differing somewhat between these 2 host species. Recent research efforts have been focused on determining if the microRNAs (miRNAs) released from adult Dirofilariae have a role as markers for distinguishing the intensity of adult worm infection, as well as determining the presence of new infections. This study expands previous work on 2 nematode miRNAs, miR34 and miR-71, by addressing their ability to discriminate between low and high D. immitis adult worm intensities in dogs. Serum samples were collected from 13 dogs, 8 of which carried known numbers of adult D. immitis at autopsy in their hearts and pulmonary vessels. Three groups of canine sera were created based on D. immitis burden: "control" (0 worms; 5 animals), "low intensity" (10-18 worms; mean ± SD = 12.3 ± 4.4; 4 animals), and "high intensity" (41-72 worms; mean 62.5 ± 15.1; 4 animals) groups. A qPCR analysis was performed on each sample to measure plasma levels of miR-34 and miR-71; however, no significant differences were observed between these groups in terms of levels of miRNAs, so the low- and high-intensity samples were then combined into a single "infected" category and compared to the "non-infected" controls. Copy numbers of both miR-34 and miR-71 were significantly higher in infected compared to uninfected animals ( P = 0.015 and P = 0.027, respectively). The Ct values of expression compared with the adult worm intensity for each miRNA revealed that both miR-34 and miR-71 significantly discriminate between the infected and non-infected groups ( P value < 0.0001 for both). These findings support the contention that miRNA 34 and miRNA 71, which are filarial-specific miRNAs, can both serve as biomarkers for the presence of D. immitis infection in dogs, but at this point they do not appear to reflect the actual intensity of adult parasites present.

Prevalence and risk factors associated with Dirofilaria immitis infection in dogs and cats in Songkhla and Satun provinces, Thailand

To update the microfilaria infection in companion animals, this study determined the prevalence and risk factors of microfilaria infection in dogs and cats collected from eight districts in Songkhla and Satun provinces, southern Thailand. In total, 482 samples (394 dogs and 88 cats) were subjected to microscopic examination (ME), polymerase chain reaction (PCR) and sequencing analysis. The overall prevalence of microfilaria infection in dogs and cats was 24.1% (95/394) and 36.4% (32/88) using PCR, respectively. Furthermore, the overall results were positive 7.7% (37/482) using ME compared to 26.3% (127/482) using PCR. Sequencing analysis of all positive PCR products identified the microfilaria as Dirofilaria immitis. D. immitis infection in each sampled district of Songkhla and Satun provinces was in the range 0–48% for dogs and in the range 15.4–75% for cats. Risk factor analysis showed that there was significantly higher D. immitis infection in dogs older than 2 yr. The study updated the prevalence of D. immitis infection in dogs and cats in two southern provinces of Thailand and there was a high D. immitis infection rate in old dogs (aged > 2 yr).

Heat treatment of serum samples from stray dogs naturally exposed to Dirofilaria immitis and Dirofilaria repens in Romania

Pre-heating of serum samples has been shown to reverse false negative antigen tests for Dirofilaria immitis infection in dogs. Here the authors report the results of serum sampling in a population of dogs naturally exposed to D. immitis and Dirofilaria repens infection by testing in ELISA before and after heat treatment. Of 194 dogs sampled from four cities in Romania, D. immitis circulating antigens were found in 16 (8.2%) non heated samples and in 52 (26.8%) heated samples. Of the 108 dogs examined by Knott test, 24 dogs (22.2%) were positive for circulating mf. Subsequent PCR identification showed six dogs had D. immitis mf only, 12 dogs, had only D. repens mf, and 5 were positive for both. Fifty% of dogs with circulating D. immitis mf had positive antigen tests before and after heating, while the other 50% reverted to positive only after heat treatment. Sixty% of dogs with mixed D. immitis/D. repens infection were antigen positive before and after heating, while the other 40% converted to positive after heating. Antigen testing for D. immitis in the 12 dogs with only D. repens mf gave conflicting results. Only two dogs (16%) were antigen negative both before and after heat treatment. Six dogs (50%) became antigen positive after heating and four dogs (30%) were antigen positive both before and after heat treatment. Results would suggest that: false negative result for antigen testing can be reverted by heating of the serum sample; dogs infected with D. repens may have also an occult infection with D. immitis; heat treatment of serum from D. repens-infected dogs can reveal an occult infection with D. immitis.

Prevalence and risk factors associated with Dirofilaria immitis infection in dogs in Makurdi, Benue State, Nigeria

Objective: This study was designed to assess the prevalence and the associated risk factors (e.g., sex, age, breed, management system and climate) of Dirofilaria immitis in dogs in Makurdi metropolis in Nigeria. Materials and methods: Prevalence study of canine heartworm disease in dogs was conducted over a period of six months covering five localities of Makurdi metropolis in Benue State, Nigeria. A total of 186 blood samples were collected from apparently healthy and sick dogs, and the samples were examined for the presence of microfilaria between September 2015 and February 2016. Three methods (wet mount, Buffy coat and modified Knott’s techniques) were used for the examination of the samples. The Packed Cell Volume (PCV) and complete blood count for each sample were also determined. Results: Out of the 186 dogs, 4 (2.15%) were found to be positive for the presence of microfilaria. Out of the 4 positive cases, 3 (1.61%) were microfilaria and 1 (0.54%) was unidentified motile parasite. A total of 104 females were examined and only 1 (0.96%) was positive, while 3 (3.66%) males out of 82 examined were positive. Out of 141 older dogs examined, 4 (2.84%) were positive. Hematology of the positive dogs revealed mild anemia and moderate thrombocytopenia with Mean±SD of 34.8±15.30% and 108±60.81x109/L, respectively. Conclusion: The study confirms Knott’s technique to be the most sensitive in the diagnosis of dirofilariasis in dogs using parasitological techniques. The findings confirm the occurrence of D. immitis in dogs in Makurdi with low prevalence and that the general public are at high risk of spreading infection from the dogs. Infection is more in male and adult dogs. This work can assist in planning appropriate strategies for controlling and prevention of D. immitis infection in Nigeria.

Right Pulmonary Artery Distensibility Index (RPAD Index). A field study of an echocardiographic method to detect early development of pulmonary hypertension and its severity even in the absence of regurgitant jets for Doppler evaluation in heartworm-infected dogs

Despite the term “heartworm disease” Dirofilaria immitis infection in dogs should be considered a pulmonary arterial disease that might only involve the right heart structures in its late stage. Chronic infection by adult heartworms in dogs results in proliferative endoarteritis leading to progressively increasing pulmonary artery pressure due to reduced elasticity. Elasticity allows the pulmonary arteries to stretch in response to each pulse and helps maintain a relatively constant pressure in the arteries despite the pulsating nature of the blood flow. Pulmonary artery distensibility for both acute and chronic pulmonary hypertension has been investigated in humans using MRI and has been correlated with the severity of hypertension and its outcome and treatment response. The aim of the present study was to investigate whether echocardiographic measurement of the percentage change in diameter of the right pulmonary artery in systole and diastole (distensibility) may be of value in assessing the presence and severity of pulmonary hypertension in heartworm-infected dogs. The Right Pulmonary Artery Distensibility Index (RPAD Index) (which is calculated as the difference in diameter of the right pulmonary artery in systole and diastole) was calculated in healthy and naturally infected heartworm-positive dogs. The right pulmonary artery was chosen because it is usually affected earlier and to a greater degree. Data were obtained from healthy heartworm-free dogs without any clinical, radiographic, or echocardiographic signs of pulmonary hypertension; naturally infected heartworm-positive dogs in different stages of the disease in which pulmonary pressure could be measured by Doppler echocardiography (using tricuspid and or pulmonary regurgitation velocity and pressure gradient); and naturally infected heartworm-positive dogs in different stages of the disease (with or without tricuspid and or pulmonary regurgitation) in which the pulmonary pressure was measured invasively and noninvasively if possible. Results of these evaluations indicated that RPAD Index is a valuable method for early detection of the presence and severity of pulmonary hypertension in heartworm-infected dogs even in the absence of regurgitant jets for Doppler evaluation and that there is a strong correlation between the RPAD Index and the level of pulmonary hypertension.

Experimental Dirofilaria immitis infection in dogs: Effects of doxycycline and Advantage Multi® administration on immature adult parasites

To better understand the efficacy of doxycycline and 10% imidacloprid+2.5% moxidectin (Advantage Multi®; Bayer Animal Health, Shawnee Mission, Kansas) on immature adult Dirofilaria immitis parasites and the results of antigen tests, 12 healthy, randomly selected dogs were experimentally infected with D. immitis and monitored for 407 days. Two dogs in each of three subgroups of four dogs were each infected with six (total of 6 dogs) or 12 (total of 6 dogs) D. immitis infective third-stage larvae (L3) obtained from infected mosquitoes. Doxycycline (10mg/kg per os twice daily×30 days) and 10% imidacloprid+2.5% moxidectin (1ml/kg by topical application every 30 days) treatment was initiated at 105 (Group A) and 149 (Group B) days post infection (PI) in two groups. One subgroup of two dogs given 6 L3 and one subgroup of two dogs given 12 L3 remained as untreated controls (GroupC). Serum obtained regularly throughout the study was evaluated by ELISA (PetChek® Heartworm-PF Antigen Test, IDEXX Laboratories, Inc.) for D. immitis adult circulating antigens. Six of the eight dogs in the treated groups had detectable antigenemia starting between 148 and 240 days post infection, but antigen was not detected in any treated dog at the end of the study. In the control subgroups, the dogs that received 6 L3 had no detectable antigen while the two dogs that received 12 L3 had detectable antigen beginning on Day 180 that persisted until the end of the study. None of the infected dogs had evidence of circulating microfilariae. At necropsy, no heartworms were recovered from the treated dogs, but all dogs in the untreated group had viable adult heartworms. These results indicate that early immature adult worms (3.5 and 5 months of age) of D. immitis were susceptible to a combined treatment regimen of doxycycline and 10% imidacloprid+2.5% moxidectin.

Prevalence of canine heartworm (Dirofilaria immitis) disease in dogs of central Portugal

The aim of the present study was to determine the prevalence and risk factors concerning Dirofilaria immitis infection in dogs from Figueira da Foz, located in the central region of Portugal. In the period between November 2009 and January 2011, 304 blood samples were obtained from dogs over 1 year of age, with no previous history of heartworm prevention or diagnosis. Every blood sample was analyzed using varied laboratory techniques (direct microscopic evaluation of a fresh blood sample, the modified Knott technique, and the ELISA antigen detection test – IDEXX Snapp®). In the samples in which microfilaremia was detected, a histochemical technique using acid phosphatase staining was applied to identify the species of microfilariae. A total prevalence of 27.3% (83 out of 304) was found. We also found that 73.5% of all positive cases (61 out of 83) were microfilaremic, and 26.5% were occult infections (22 out of 83). By means of a histochemical technique Dirofilaria immitis was identified in 96.7% of microfilaremic samples. A multivariate model allowed us to identify the following risk factors for the presence of heartworm disease: age between 4 and 9 years, dogs living in a rural environment, large breed dogs, and living outdoors. This study shows for the first time the high prevalence of heartworm disease in a central area of Portugal and emphasizes the importance of systematic screening for this disease, as well as the need to prevent it in dogs in this area.

Detection of heartworm infection in dogs via PCR amplification and electrospray ionization mass spectrometry of nucleic acid extracts from whole blood samples

To develop and evaluate a rapid and accurate assay involving PCR amplification and electrospray ionization mass spectrometry of nucleic acid extracts from whole blood samples for the detection of Dirofilaria immitis infection in dogs. Whole blood nucleic acid extracts from 29 dogs experimentally infected with D immitis (and in which circulating D immitis antigen was detected) and 10 uninfected dogs. 16 of the 29 whole blood samples from infected dogs were examined at the time of collection for circulating microfilaria. Nucleic acids were extracted from all whole blood specimens and underwent PCR amplification with 12 PCR primer pairs designed to detect a wide range of pathogens (including the Wolbachia endosymbiont of D immitis) and electrospray ionization mass spectrometry. On the basis of assay results, heartworm infection was detected in 13 of 13 antigen-positive dogs of unknown microfilaria status, 11 of 11 antigen-positive dogs with circulating microfilaria, 0 of 3 antigen-positive dogs tested at 3 months after larval infection, 0 of 2 antigen-positive dogs with occult infections, and 0 of 10 uninfected dogs. With the assay under investigation, it was possible to identify D immitis infection in dogs with circulating microfilaria via detection of the obligate Wolbachia endosymbiont of D immitis. It was not possible to identify dogs with occult infections, which suggested that circulating microfilaria must be present to detect infection with this assay, although further studies would be required to verify that finding.

Dirofilaria immitis infection in dogs: Cardiopulmonary biomarker levels

Cardiopulmonary biomarkers are biological parameters that can be objectively measured and quantified as indicators of pathogenic processes (heartworm disease) or as indicators of response to therapeutic intervention. To determine levels of cardiopulmonary biomarkers in canine dirofilariasis, measurements of cardiac troponin T, cardiac troponin I, myoglobin, and D-dimer concentrations were performed for dogs with and without evidence of adult heartworm infection. The results showed that levels of cardiac troponin T were undetectable in all dogs studied while levels of cardiac troponin I were higher in dogs infected with Dirofilaria immitis. In healthy dogs, levels of myoglobin and D-dimer were below detection limits of the instrument and were significantly higher in heartworm-infected dogs, notably in microfilaremic dogs. The results suggest the possibility of using troponin I and myoglobin as markers for cardiac damage and the D-dimer as a supportive tool for a diagnosis of pulmonary thromboembolism in dogs with cardiopulmonary dirofilariasis.

Prevalence of canine Dirofilaria immitis infection in the city of Algiers, Algeria.

Heartworm disease is caused by Dirofilaria immitis a zoonotic, vector-borne parasite and one of the most pathogenic nematode parasites of the dog. The epidemiological status of this parasitosis in Algeria stays to this day unknown even though this country has the ideal biotope to the development of this disease. The aim of this study was to investigate the prevalence of D. immitis infection in dogs from Algiers, in the north of Algeria. Blood samples were collected from 184 dogs from November 2006 to September 2007 and were examined by the modified Knott method to detect circulating microfilaria. A total of 34 subjects were microfilaria positive, giving a prevalence value of 18.48%. All the samples were further tested by antigen-ELISA in order to detect dogs with prepatent or occult heartworm infections. The prevalence rose to 24.46% (with 45 seropositives dogs). More male (14.13%) than female (10.33%) dogs were affected in this study, although there was no significant difference between both groups. With regard to general health status, our datashowed a high prevalence of 18.48% of asymptomatic carriers of the parasite D. immitis, only 5.98% of the positive samples were from unhealthy dogs. The difference was statistically significant (p < 0.05). This first report on the status of D. Immitisinfection in domestic dogs in Algiers, suggests that heartworm treatment and adequate prophylaxis should be undertaken to control D. Immitis infection in the canine population of Algiers city in Algeria. Key words: Dirofilaria immitis, prevalence, ELISA, sexe distribution, dogs, Algiers.