Immitis Infection Research Articles

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.

First autochthonous Dirofilaria immitis (Leidy, 1856) infection in a dog in Hungary

Abstract A 4 year-old, male Hungarian Vizsla dog which had never been abroad was referred with poor general condition, decrease in body weight, haematemesis and jaundice to the Central Clinic of Veterinary Science University, Budapest. After symptomatic treatment abdominal ultrasonography and diagnostic laparatomy were carried out. The dog was humanely euthanized two days later following owner’s consent because of sudden worsening of clinical conditions. Two adult heartworms (Dirofilaria immitis) were found in the right ventricle partially coiling around the tricuspid valve. PCR on blood was positive for both D. immitis and Dirofilaria repens while only D. repens microfilariae were found by modified Knott’s test and the serological test was negative for D. immitis antigens. This is the first, confirmed report of autochthonous canine heartworm infection in Hungary.

ZoonoticDirofilaria immitisinfections in a province of Northern Spain

Dirofilaria immitis is the causal agent of canine and feline cardiopulmonary dirofilariasis. Moreover, the existence of canine dirofilariasis implies a risk for human populations living in an endemic area in which, the parasite can cause pulmonary dirofilariasis. The Spanish epidemiological situation is not well understood, lacking data from many central and Northern provinces. In our study, epidemiological data on canine and human dirofilariasis for La Rioja (Northern Spain) have been obtained for the first time. The overall prevalence of D. immitis in dogs was 12% (9% of patent and 3% of occult infections), being 11.6% the seroprevalence of human residents in this province. The geographic distribution of both canine and human D. immitis infections in La Rioja is restricted to humid and irrigated areas near the Ebro Valley River, being absent in the rest of the province where hills and mountains predominate.

First document on the presence of Iraqi Dirofilaria immitis

Canine dirofilariasis in Iraq was thought not present. This is the first report of dogheartworms in our country. Hearts of 22 dogs from various sites in Kerbala province wereexamined for Dirofilaria immitis infection. Peripheral blood from dogs with worms in theheart was examined for microfilaria. Adult worms were found in 16 (73%) hearts.Microfilaria in blood not tackled in the present work. From these finding we hypothesis thatheartworm disease is usually present in / or imported from those areas that are endemic forcanine dirofilariasis

Heartworm (Dirofilaria immitis) disease in a Brazilian oncilla (Leopardus tigrinus)

Heartworm disease is caused by the intravascular nematode Dirofilaria immitis, a pathogen of public health importance usually associated to domestic dogs and cats, and to a lesser extend to other mammal species. The oncilla (Leopardus tigrinus) is a threatened neotropic felid species that naturally occurs in Brazil. Here, we report the encounter of adult and larval stages of heartworms in a female specimen of L. tigrinus, probable of free-ranging origin, from Ubatuba, São Paulo, Brazil, which died showing clinical signals compatible with heartworm disease. This was the first reported case of D. immitis infection and associated disease in L. tigrinus, also suggesting that the oncilla acted as a definitive host for this parasite. The present findings confirmed D. immitis as a pathogenic agent for this felid species, thus supporting the recommendation for the inclusion of diagnostic testing for this pathogen in routine health screening procedures for captive and free-ranging oncillas in Brazil, especially in those localities where climate conditions support the occurrence of the parasite. Potential reservoirs as oncillas are established beyond the reach of veterinary care, thus representing a continuing risk for domestic animals and humans acquiring heartworm infection. We encourage further serologic and molecular studies aiming to establish D. immitis prevalences in L. tigrinus and other wild carnivores in the region of Ubatuba, as well as ecological and veterinary studies to access the role of this pathogen for the survival of this threatened felid species.

Climate and Dirofilaria infection in Europe

Climatic changes, together with an increase in the movement of cats and dogs across Europe, have caused an increase in the geographical range of several vector borne parasites like Dirofilaria, and in the risk of infection for animals and humans. The present paper reviews the effects of climate and other global drivers on Dirofilaria immitis and Dirofilaria repens infections in Europe and the possible implications on the transmission and control of these mosquito-borne nematodes. In the last several years, growing degree day (GDD)-based forecast models, which use wide or local scale temperature data, have been developed to predict the occurrence and seasonality of Dirofilaria in different parts of the world. All these models are based on the fact that: there is a threshold of 14 °C below which Dirofilaria development will not proceed; and there is a requirement of 130 GDD for larvae to reach infectivity and a maximum life expectancy of 30 days for a vector mosquito. The output of these models predicts that the summer temperatures (with peaks in July) are sufficient to facilitate extrinsic incubation of Dirofilaria even at high latitudes. The global warming projected by the Intergovernmental Panel on Climate Change suggests that warm summers suitable for Dirofilaria transmission in Europe will be the rule in the future decades and if the actual trend of temperature increase continues, filarial infection should spread into previously infection-free areas. These factors not only favour incubation of Dirofilaria, but also impact on mosquito species. Recent findings have also demonstrated that Aedes albopictus is now considered to be an important, competent vector of Dirofilaria infections. This mosquito species could spread from southern to northern European countries in the near future, changing the epidemiological patterns of dirofilariosis both in humans and animals.

Inhibition and Prevention Efficacy against Mosquito Bloodsucking and Dirofilaria immitis Infection by Administration of Topical Insecticide

Inhibition and prevention of mosquito bloodsucking by a topical insecticide, and the consequent infection of Dirofilaria immitis were evaluated using a product containing 10% w/w imidacloprid plus 50% w/w permethrin (I-P solution). Nine healthy beagle dogs divided in three groups of 3 dogs each were administered I-P solution on day 3 (group 1), day 36 (group 2) and not administered (group 3 as a control) before starting the experimental infection. The results showed that the mosquito bloodsucking rate was significantly lower, 12.1% in group 1 (p<0.05) and 11.1% in group 2 (p<0.05), than the 40.6% in group 3, meaning that the inhibition rates in groups 1 and 2 against group 3 were 70.2% and 72.7%. The infection rate of experimental D. immitis infection was 33% in group 1, 33% in group 2 and 100% in group 3, meaning that the prevention rates in groups 1 and 2 against group 3 were 67% and 67%.

Dirofilaria immitis (Leidy, 1856) no entorno de um caso felino: um estudo sobre sua transmissão

Dirofilaria immitis preferably infects canids and can, in lower frequency, be found in cats (Felis catus Linnaeus, 1758). The parasite may be transmitted by various Culicidae species. Motivated by an autochtone feline heartworm case diagnosed in the region of Engenho Novo - RJ (S 22 degrees 90' e WO 43 degrees 27'), the following issues were surveyed: 1) the local Culicidae fauna and; 2) the ocurrence of microfilaremic dogs. The mosquito study was conducted from April 2003 through May 2004, by peri-domiciliary and intra-domiciliary captures. A total of 672 mosquitoes (female) of the following species were caught: Aedes aegypti (Linnaeus) (561/672-83.5%); Culex quinquefasciatus Say (96/672-14.3%); Aedes (Oc.) scapularis (Rondani) (12/672-1.8%) and Aedes albopictus (Skuse) (3/672-0.4%). Only A. aegypti and C. quinquefasciatus specimens were captured year-round. A total of 235 canine blood samples were collected during the Campanha de Vacinação "Rio Sem Raiva" in October 2003. No microfilaria could be found in any of the examined samples (Knott s and NAN techniques), even though only 3.4% of the dogs received chemoprophylaxis and the majority of them frequently traveled to endemic areas. The presence of vectors associated to a possible dog mobility, may have provided the right scenario for the feline D. immitis infection to happen in the studied area.

Feline heartworm ( Dirofilaria immitis) infection: A statistical elaboration of the duration of the infection and life expectancy in asymptomatic cats

A study was conducted to assess the duration and the outcome (self-cure or death) of feline heartworm infection and the life expectancy of infected cats. To be included in the study, cats had to be positive for heartworm antibody (Ab) and heartworm antigen (Ag) and had to demonstrate the presence of worms by echocardiography. Self-cure was defined as (1) negative for heartworm Ag and (2) no further visualization of worms by echocardiography. Of the 1962 eligible cats, 364 (18.5%) were positive for heartworm Ag and 131 were positive for heartworm Ag and for echocardiography diagnosis (prevalence 6.7%). None of the cats was microfilaremic. Of 43 asymptomatic cats included into the follow-up study with owners’ consent, 34 (79%) self-cured and nine (21%) died. Eleven (26%) cats remained asymptomatic and self cured within 21–48 months, 23 (53%) showed symptoms but self-cured within 18–49 months, 6 (14%) died within 8–41 months of follow-up and 3 (7%) suddenly died after 38–40 months, which was related to heartworm infection. The probability for death or sudden death increased significantly with age at diagnosis, but no difference was detected by gender, survival time after diagnosis, or the presence or absence of symptoms. The presence/absence of symptoms showed significant interaction with the age at diagnosis (i.e., symptomatic cats showed increasing duration of heartworm infection along with age at diagnosis compared to that for asymptomatic cats. Heartworm-infected cats survived significantly longer than heartworm-negative cats affected by hypertrophic cardiomyopathy, chronic renal failure, or neoplastic diseases.

Serological and molecular studies onDirofilaria immitisin dogs from Turkey

We estimated the prevalence of Dirofilaria immitis infection in domestic dogs in five Turkish provinces - Sakarya, Kocaeli, Ankara, Elazig and Mersin - using a commercial ELISA kit for detecting circulating antigen and a PCR test for detecting circulating microfilarial DNA. A total of 211 whole-blood and serum samples were collected from dogs of various breeds, ages and life status (owned or stray). Sample population characteristics were recorded and examined for differences in prevalence. Additionally, we collected 15 blood samples from cats (14 owned and 1 stray) from Ankara province and used PCR to detect D. immitis infection. Twenty-seven (12.8%) of 211 dog samples were positive for D. immitis antigen by ELISA. No differences in prevalence were observed by sex (female: 14.4%; male: 10.7%; P>0.05). The prevalence of D. immitis infection varied with age: 11.8% in younger dogs (0.5-2 years) and 17.5% in older dogs (3-5 years). Prevalence between stray dogs (15.2%) and owned dogs (9.3%) did not differ (P>0.05). Prevalence rates were highest in Kocaeli province (18.3%), followed by Ankara (14.8%), Sakarya (12.3%) and Mersin (10.5%) provinces. Prevalence in Elazig province was 0%. No dogs or cats had microfilarial DNA detectable by PCR.

Coccidioidomycosis in a 38‑year‑old man: a case report

The present article describes a case of acute pulmonary coccidioidomycosis in a 38-year-old man, a research worker. The disease started during the patient stay in Arizona, USA, and clinical symptoms persisted after his return to Poland. Acute coccidioidomycosis is one the clinical manifestations of Coccidioides immitis strain endemic infections occurring in the south-western regions of USA including California (mainly San Joaquin Valley), Western Texas, New Mexico and the desert areas of Arizona, and Central and South America. The native environment of Coccidioides immitis is soil penetrated by rodents. People, domestic and wild animals suffer from coccidioidomycosis. The infection rate in endemic areas is about 2-4% a year in the healthy population. Coccidioidomycosis can be observed in non-endemic areas due to population mobility and in immunocompromised patients. The Coccidioides immitis infection is caused by inhaled airborne fungal spores and it may occur as primary pulmonary (acute or chronic) asymptomatic form, meningitis, or disseminated disease. The clinical symptoms of coccidioidomycotis like acute pulmonary manifestations may resemble typical, resistant to empiric antibiotic treatment of bacterial pneumonia. In healthy subjects, pulmonary coccidioidomycosis may occur as asymptomatic infection, which resolves spontaneously without medication. Sometimes, slight shadows like local fibrosis and cavities may be visible on the chest X-ray. The Coccidioides immitis infection in people with immunological deficiency syndromes, e.g. HIV/AIDS, manifests itself as disseminated disease and may lead to severe complications including death.

Field efficacy and safety of a combination of moxidectin and imidacloprid for the prevention of feline heartworm ( Dirofilaria immitis) infection

Throughout the end of March to beginning of May 2006, 212 owned cats and 608 owned dogs from a heavy endemic area for canine heartworm (HW) disease in northern Italy have been examined to assess HW infection prevalence. Both cats and dogs were clinically examined and blood samples were taken from each animal to be examined for HW antibody (Ab). Ab-positive cats were further examined for circulating microfilariae, HW antigens (Ag) and by echocardiography (ECHO) to assess the presence of adult worms. Dogs were clinically examined and blood samples taken from each animal were examined for circulating microfilariae and for HW Ag. Ten cats (4.7%) were found Ab positive. Of these, 6 cats were Ag positive (2.6%) and in 4 (1.8%) the worms were visualized by ECHO. HW prevalence in dogs was 36% (221/608). One hundred and seventy-six (29%) were both microfilaraemic and Ag positive, 40 (7%) had occult infections (no circulating microfilariae) and 7 (1%) were microfilaraemic but Ag negative. Upon owners’ consent, 132 cats (including cats Ab and/or Ag and ECHO positive) were prophylactically treated against HW disease with an imidacloprid/moxidectin spot-on combination (10% imidacloprid/1% moxidectin) monthly administered for 6 months. Cats were re-examined for HW infection in November, 1 month after the last drug administration, and in May–June 2007, 7–8 months after the last treatment. All 122 cats found HW negative before treatment, were found negative at the two examinations at the end of study. The 4 cats Ab positive, 2 cats Ab and Ag positive and 1 Ab, Ag and ECHO positive at the beginning of treatment were found negative. Throughout the treatment, transitory hypersalivation and generic signs of annoyance were reported by owners in 6 cats (4.5%). All signs regressed spontaneously.

Myocardial fluid balance in dogs with naturally acquired heartworm infection

To determine the effect of naturally acquired heartworm (Dirofilaria immitis) infection on myocardial fluid balance as indicated by myocardial water content and the dynamics of transepicardial fluid flow. 7 dogs infected with adult heartworms and 8 dogs free of heartworm infection. Infected dogs had heartworms in the right ventricle, pulmonary artery, or both but no evidence of cardiovascular disease on physical examination. A hemispheric capsule was attached to the epicardial surface of all dogs for determination of transepicardial fluid dynamics and permeability of the epicardium to water and protein. Myocardial water content and hydroxyproline content were assessed at necropsy. Myocardial water content was significantly lower in heartworm-infected dogs. No differences in myocardial hydroxyproline content, transepicardial fluid flow, or epicardial water or protein permeability were detected. Heartworm infection significantly altered myocardial fluid balance in dogs, possibly because of a change in the myocardial interstitial pressure-volume relationship. These changes may be associated with increased vulnerability to cardiovascular stressors in heartworm-infected dogs.

Intraarticular Dirofilaria immitis microfilariae in two dogs

Dirofilaria immitis microfilariae were found in the synovial fluid of two dogs. One dog had clinical and cytological evidence of polyarthritis at the time of presentation. The second dog presented with severe effusion in a single joint and was later diagnosed with synovial sarcoma of the affected joint. These patients were not protected with heartworm prophylaxis and lived in heartworm endemic areas. Though there is documentation of D. immitis microfilaria in the synovial fluid of several clinically normal research dogs with cytologically normal synovial fluid, to our knowledge these are the first documented cases of intraarticular microfilaria in a dog with cytologically confirmed polyarthritis. Based on these unique cases, D. immitis infection should be considered a differential diagnosis in patients with polyarthropathies. Interpretive caution must be used when intraarticular microfilaria are present, as concurrent etiologies may also be present.

The Role of IL‐10 in Genetic Susceptibility to Coccidioidomycosis on Mice

Epidemiological and clinical studies have confirmed that coccidioidomycosis is more severe in African American and Filipino patients than in Caucasians, suggesting a genetic basis for susceptibility in humans. We discovered that inbred strains of mice also vary greatly in their susceptibility to Coccidioides immitis infections, and although resistance is the dominant phenotype, it is a multigenic trait in mice. We found a strong direct correlation between susceptibility in mice and the amount of IL-10 made in response to infection. We then showed that IL-10-deficient mice are much more resistant to infection than the parent C57BL/6 strain. Finally, we showed that genetically resistant mice that are transgenic for IL-10 and so overproduce that cytokine are more susceptible to C. immitis. This is in part due to suppression of NOS2 expression by IL-10.

Design and Testing of a Natural Dirofilaria immitis Infection Model to Evaluate the Safety of an Imidacloprid plus Moxidectin Combination in Cats

The safety of heartworm-preventative products in heartworm-positive cats has traditionally been evaluated with a study design where adult D. immitis are removed from infected dogs and surgically implanted into cats. An alternate study model was developed to establish adult infections in cats for subsequent product safety testing. Eighty adult cats were each inoculated with 60 D. immitis L3 on test day (TD) 1. The cats then were maintained for eight months to allow for the development of adult worms. Antigen/antibody testing, as well as echocardiographic imaging, were performed to confirm and estimate adult worm burdens. Thirty-five cats determined to have clinically relevant D. immitis infections were blocked by infection intensity score and randomised to one of four treatment groups: 1) 0x (nine cats); 2) 1x dose imidacloprid + moxidectin (nine cats); 3) 5x dose of imidacloprid +moxidectin (nine cats); and 4) selamectin 1x dose (eight cats). Treatments were topically administered on TD 250. Cats in groups 1, 2 and 4 received additional treatments on TD 278 and 306. On TD 288, group 3 cats were euthanised for recovery of adult heartworms. All other cats were euthanised on TD 334. No adverse events attributable to treatment with the test articles were observed during the study. The geometric mean numbers of adult D. immitis recovered from groups 1–4 were 2.73, 2.86, 3.24 and 3.97, respectively. There were no statistically significant differences in the adult D. immitis recovery between groups (p = 0.5356). The results of the study indicate that cats currently infected with D. immitis can be safely treated with 10% imidacloprid + 1% moxidectin, even at dosages five-fold higher than recommended for clinical use.

Imidacloprid plus Moxidectin to Prevent Heartworm Infection (Dirofilaria immitis) in Ferrets

Ferrets are susceptible to Dirofilaria immitis infection and develop a disease comparable to that in cats and dogs. Treatment options are limited, thus prevention would be a viable alternative. A study was conducted to evaluate the efficacy of a combination of 10% w/v imidacloprid plus 1.0% w/v moxidecin spot-on to prevent patent D. immitis infection in experimentally infected ferrets when administered once 30 days post-infection. Twelve ferrets were acclimated to the study facility for seven days. The ferrets were free of heartworm infection prior to the artificial infection, as demonstrated by negative test results onmicrofilarial and antigen tests. On study day −30, the twelve ferrets were artificially infected with 25 infective, thirdstage larvae of D. immitis. On study day −1, the twelve ferrets were randomised and allocated to two study groups so that each group contained six ferrets. On study day 0, the animals assigned to group 1 were treated with a combination of 10% imidacloprid / 1% moxidectin at a dose of 0.4 ml per ferret. The animals assigned to group 2 served as untreated controls. On study day 124, the ferrets in both study groups were euthanised and necropsied to determine the worm burden. Ferrets in the control group (group 2) were adequately infected with D. immitis at necropsy to allow assessment of the treatment group in this study (GM = 17.2worms). The efficacy of a combination of 10% imidacloprid / 1.0% moxidecin against artificial infections with D. immitis in ferrets was 100% when administered once, at a target dosage of 0.4 ml, 30 days post-infection. No adverse events were observed which were considered to be treatment related.

Dirofilaria immitis infection in dogs: unusually located and unusual findings

Clinical, blood, serum biochemistry, and parasitological assessments were performed on four hospitalized dogs, not in good general condition, in a study carried out to determine the prevalence of general parasitic infections. Hematological and biochemical parameters and electrocardiographic recording of the animals were determined during the general clinical examinations. Four dogs were indicated to have been infected with Dirofilaria immitis by using modified Knott's method, and the microfilarial density was determined. Mild to moderate anemia and decrease in sedimentation velocity were established in dogs. Differences in other hematological and biochemical values between the dogs were determined. Right axis deviation was determined in a dog. D. immitis was encountered in the right ventricle, bronchus, and the pericardial sac at the end of the necropsy. On the other hand, in the histopathological examinations, pulmonary adenocarcinoma deriving from bronchial epithelium was identified in a dog, and microfilaria was encountered in bronchial and bronchiolar lumens, interstitium of the lungs, and bile ducts. D. immitis has not been considered in the diagnosis of dogs with pneumonia and tumors. The requirement of parasitological examination with respect to D. immitis in the diagnosis of dogs with tumor or pneumonia has been considered vital.

Prevalence of the Dirofilaria immitis infection in dogs from Merida, Yucatan, Mexico

The aim of the present study was to estimate the prevalence of Dirofilaria immitis infection, and to examine the relationship between host factors (gender, age and breed) and D. immitis infection in dogs. The study was designed as a cross-sectional study. A total of 676 dogs were examined for D. immitis infection. Adult worms (necropsy) and blood samples were collected from all animals for diagnosis of D. immitis. Blood samples were examined using a modified Knott's and thick drop techniques. Fifty-six of 676 dogs were diagnosed infected with D. immitis. The odds of infection were 2.85 times higher in female dogs, compared to male dogs (OR = 2.85, 95% CI = 1.5–5.5, P = 0.01). In addition, the odds of infection were 2.11 times higher in ≥3 years old dogs, compared with younger dogs (OR = 2.11, 95% CI = 1.1–4.2, P = 0.03). This information is important for a better understanding of the epidemiology of D. immitis in dogs in Yucatan, Mexico.

Changes in the levels of eicosanoids in cats naturally and experimentally infected with Dirofilaria immitis

Feline heartworm (Dirofilaria immitis) infection is a severe, life-threatening disease. The eicosanoids are lipid mediators derived from the metabolism of the arachidonic acid, involved in the regulation of the immune response and of inflammatory reactions. In this study, naturally infected cats showed significant higher levels of prostaglandin E2 (PGE2), thromboxane B2 (TXB2) and leukotriene B4 (LTB4) than uninfected cats. Changes in the levels of eicosanoids during the infection were observed in experimentally infected cats. PGE2 increased significantly during the first 60 days post-infection, then progressively decreased until day 180 post-infection. At this time, PGE2 values are still significantly higher than those observed before the infection. TxB2 and LTB4 increased progressively from the beginning of infection and reached their maximum levels 180 days post-infection. In experimentally infected, ivermectin-treated cats, 15 days after treatment (45 days after infection) both PGE2 and LTB4 levels were similar to those observed in experimentally infected, untreated cats. No significant differences of PGE2 levels were found before the infection and at the end of the experiment (165 days post-treatment, 195 days post-infection). Increased levels of LTB4 were found 15 days post-treatment, afterward they progressively decreased. These data show that D. immitis infection influences the production of intravascular eicosanoids in cats. The high levels of PGE2 observed in the early phase of infection could be related to the survival of the worms, while those of TxB2 and LTB4 detected at the end of the study could mediate the inflammatory reactions and thrombi formation during the feline dirofilariosis.