Immitis Infection Research Articles

Smooth Muscle Proliferation in Chronically Injured Canine Pulmonary Arteries Is Reduced by a Potent Platelet Aggregation Inhibitor U-53,059

Dirofilaria immitis (DI) infection chronically injures canine pulmonary arteries. This injury produces endothelial cell loss, platelet/leukocyte adhesion, and smooth muscle proliferation. In the present study we assessed the effect of the cyclooxygenase inhibitor, U-53,059, on platelet function, platelet kinetics, coagulation, and smooth muscle proliferation in DI infected dogs. Platelet aggregation to the combination of arachidonic acid/ADP was significantly inhibited by U-53,059. Coagulation and hematologic parameters were not effected by either DI infection or U-53,059 treatment. Platelet survival and the number of platelet dense granules were reduced in DI infection. Quantification of the lesions demonstrated that U-53,059 reduced both severity and density compared to non-treated dogs. U-53,059 is a potent and effective inhibitor of platelet aggregation which modifies smooth muscle proliferation produced by chronic vascular injury.

塩酸レバミゾールの間欠投与による野外での犬糸状虫の予防効果

塩酸レバミゾールの間欠投与による野外での犬糸状虫の予防効果

塩酸レバミゾールの間欠投与による犬糸状虫の予防試験

塩酸レバミゾールの間欠投与による犬糸状虫の予防試験

Prophylactic efficacy of milbemycin D against Dirofilaria immitis infection in dogs.

To examine the prophylactic efficacy of milbemycin D against Dirofilaria immitis infection, 59 filaria-free beagles were inoculated with 50 to 100 infective larvae of the parasite. Milbemycin D was administered orally at ranges from 0.05 to 3.2 mg/kg of body weight one month after inoculation or at the rate of 1 mg/kg of body weight one to 90 days after inoculation. All dogs were sacrificed for autopsy 6 months after inoculation to confirm the establishment of D.immtis infection. Complete protection from the infection was observed by treating with a dose of 1 mg/kg or more of milbemycin D one or two months after infection.

An investigation of the role of immunologic factors in anemia associated with canine heartworm disease

Direct Coombs' antiglobulin tests were performed on 80 dogs with patent Dirofilaria immitis infection and 170 dogs negative for microfilaria of D. immitis . Presence or absence of anemia was determined by hematocrit in 55 of the heartworm negative dogs and 68 of the dogs with heartworm disease. Heartworm infected dogs showed a higher incidence (37%) of anemia than noninfected dogs (14.5%). Anemia was most prevalent in two groups of dogs with heartworm infection, one group showing vena caval syndrome (91%) and the other occult dirofilariasis (62.5%). These latter two groups of dogs also showed a significantly higher number of positive Coombs' reactions at 37°C than other dogs with heartworm disease and the noninfected dogs. The number of positive Coombs' reactions at 4°C among the total of 80 dogs with heartworm infection was significantly higher than that for dogs without heartworm disease. However, there was no positive correlation between anemia and the outcome of the Coombs' test at either temperature. These findings do not suggest that immunologic factors play a major role in the pathogenesis of anemia in dogs with heartworm disease.

Immunological and ultrastructural aspects of the cell-mediated killing of Dirofilaria immitis microfilariae.

Neutrophils in the presence of serum from dogs with occult Dirofilaria immitis infections were shown to be cytotoxic to D. immitis microfilariae recovered from the blood of microfilaraemic dogs. This cytotoxicity was correlated with the presence of IgM and IgG antibodies on the cuticular surface of microfilariae incubated in the sera from occult dogs. Such antibodies were not observed on the surface of microfilariae incubated in sera from microfilaraemic or normal dogs. The neutrophil attack was directed at the cuticular crypts, at which sites the worms appeared to be structurally most vulnerable because of the absence of the outer layer of the cuticle. The IgM antibodies were shown to be bound preferentially to these sites. Our data suggested that the neutrophil-mediated toxicity involved both hydrogen peroxide release and degranulation.

Reactivity to spherule-derived coccidioidin in the southeastern United States.

Delayed hypersensitivity skin tests with mycelium-derived (coccidioidin) or spherule-derived (spherulin) antigens (or both) can be used to identify patients who have been sensitized to the dimorphic fungus Coccidioides immitis. Prior studies suggest that coccidioidin and spherulin skin test antigens detect comparable numbers of reactors among exposed subjects. Studies in subjects residing in areas outside the United States where C. immitis is not endemic suggest that both antigens are specific for the fungus. The specificity and reactivity of coccidioidin and spherulin have not been compared in nonendemic regions of the United States in which the skin test antigens and an appropriate travel or exposure history are used to identify patients with possible C. immitis infection. A review of delayed cutaneous reactions to coccidioidin in 6,375 patients tested between 1970 and 1979 in the southeastern United States revealed 958 (15.0%) and 234 (5.7%) positive reactions (greater than or equal to 5 mm), respectively, at 24 and 48 h. Subsequent tests with spherulin in 2,775 patients tested in 1980 and 1981 revealed 866 (31.2%) and 288 (10.3%) positive reactions, respectively, at 24 and 48 h. False-positive immediate hypersensitivity reactions contributed to the large number of spherulin reactors at 24 h. Differences among the patients sampled, work exposure, and travel history were excluded as causes of this surprising and highly significant (P less than or equal to 0.0001) difference in the 48-h delayed cutaneous reaction. These observations suggest two possibilities: (i) spherulin is less specific than coccidioidin, or (ii) a surprising prevalence of C. immitis sensitization exists among patients in nonendemic regions of the United States.

Landscape epidemiology of mosquito-borne canine heartworm (Dirofilaria immitis) in northern California, USA. I. Community-based surveys of domestic dogs in three landscapes.

Endemic patterns of canine filariasis in northern California were studied in 3 communities differing in ecological landscape: Tehama City (riparian-agricultural), Palo Cedro (oakpine woodland), and Cedar Ridge (conifer-oak forest). Dog populations were surveyed by household for canine-infecting filariids; both microfilaremic and amicrofilaremic patent Dirofilaria immitis infections were documented (Knott, IFA/ELISA tests). Of 403 dogs resident in these communities, 111 were on preventive diethylcarbamazine (DEC) citrate therapy (55% tested), and 292 had no recent DEC history (87% tested). Dirofilaria immitis was highly endemic in all communities, with point prevalence rates of 34.3% (Tehama City), 28.0% (Cedar Ridge), and 21.1% (Palo Cedro). Amicrofilaremic occult infections constituted 14–29% of total cases. The frequency distribution of microfilaremic densities in community dogs was highly skewed (median = 4040 mf/ml). Dipetalonema reconditum microfilariae were found in 4.9% of dogs in the Tehama community. Significant heartworm risk factors were Residence period, exposure, and SEX as determined from stepwise logistic regression analysis. Heartworm risk increased with length of residence, compared to a reference population resident ≤ 1 year. Adjusted odds ratios were 3.1 in dogs resident 1–3 years, 5.5 (3–5 years), and 12.2 (>5 years) (98.7% confidence). Dogs kept strictly outside were at 5.4× greater risk of patent heartworm disease than animals kept indoors for at least part of the 24-h day (97.5% confidence). Increased risk was also quantified for spayed females (R = 4.2) and for all males (R = 3.0), compared to intact females (98.3% confidence). Heartworm cases in Cedar Ridge were clustered adjacent to areas of disrupted forest landscape, suggesting a focal mosquito vector originating from the disturbed area. In Tehama City, cases were evenly scattered throughout the town, suggesting highly dispersive mosquito vector populations. The spatial distribution of cases in Palo Cedro indicated a woodland-associated vector with limited dispersal ability. Dipetalonema reconditum cases were mostly clustered by neighborhood in Tehama City.

Pulmonary Disease: An Annotated Bibliography of Recent Literature

Pulmonary Disease: An Annotated Bibliography of Recent Literature

Amphotericin B and imidazole therapy for coccidioidal meningitis in children.

Coccidioidal meningitis is a fatal form of Coccidioides immitis infection. Amphotericin B (AMB) therapy has reduced mortality but is itself toxic, and experience with it in very young children is meager. We are treating six children for coccidioidal meningitis diagnosed at 19 to 74 months of age. All had acute hydrocephalus and ventriculitis. The first four patients were initially treated with AMB but were changed to imidazole therapy (miconazole and ketoconazole). In the last two patients therapy was begun with the imidazoles. Ommaya reservoirs for cisternal therapy have been of limited usefulness. AMB therapy has been limited by local and systemic toxicity and by failure in one case. All children have improved with 15 to 22 mg oral ketoconazole per kg per day and 3 to 5 mg intraventricular miconazole for instillation therapy, including those with noncommunicating hydrocephalus in whom the intraventricular drug does not reach the basilar cisterns. Peak concentrations of ketoconazole in ventricular fluid were 0.08 to 5.6 micrograms/ml. Shunt obstruction and bacterial superinfections have been the major causes of morbidity. Imidazole therapy of coccidioidal meningitis may be more effective than is AMB in young children, and it offers the advantages of fewer side effects and not requiring intrathecal or cisternal administration.

Effects of gregarine parasites on the development of Dirofilaria immitis in Aedes triseriatus (Diptera: Culicidae).

Infections of Aedes triseriatus with the gregarine parasite Ascogregarina barretti were examined to determine the influence of this parasite on host development and survival, and to quantify the effects of this parasite on Dirofilaria immitis development. Infections with A. barretti caused a reduction in the weight of female pupae and a slight increase in the time to pupation of males. Male pupal weight, female time to pupation, larval mortality, adult emergence, and adult male survival were not affected by A. barretti. Over 95% of the gregarine-infected and uninfected adult females that ingested comparable levels of microfilariae of D. immitis became infected, and in over 90% of the mosquitoes D. immitis completed development to the infective L3 stage. No significant differences in the number of infective larvae were found between gregarine-infected and uninfected mosquitoes. However, in the Malpighian tubules, significantly more L3 and L2 larvae were found in gregarine-infected mosquitoes. The survival of adult female Ae. triseriatus was not influenced by either gregarine infections, D. immitis infections, or concomitant infections with both parasites. Overall, infections of A. barretti do not appear to affect the vector competence of Ae. triseriatus for D. immitis.

In vitro immune mechanisms associated with clearance of microfilariae of Dirofilaria immitis.

An in vitro system has been developed to elucidate potential immune mechanisms associated with clearance of microfilariae (Mf) from the bloodstream in canine Dirofilaria immitis infection. Granulocytes as well as mononuclear cells adhere to Mf of Dirofilaria immitis in the presence of immune serum. Only granulocytes, however, were capable of killing Mf, whereas PBMC attach to but do not effectively kill Mf. In the presence of granulocytes 1% +/- 1, 10% +/- 2, and 12% +/- 3 of Mf were killed by heated normal (NDS), patent (PS), and occult serum (OS), respectively, after an 18-hr incubation. With the addition of fresh NDS there was an increase in killing to 5% +/- 1 (p less than 0.025) with heat-inactivated NDS, to 12% +/- 3 in the presence of PS and to 77% +/- 12 (p less than 0.005) in the presence of OS. On further purification of granulocyte cell populations with metrizamide gradients, neutrophils were found to be the predominant effector cells with 73% +/- 18 killing with neutrophils and 18% +/- 6 with eosinophils (p less than 0.0005). Only with neutrophils was a significant increase in killing of Mf observed when fresh NDS was added to delta OS. Fractionation of OS by gel filtration suggested that IgM was the opsonizing antibody in the occult serum. In addition, immunofluorescent studies showed only IgM bound to the surface on Mf on incubation in OS. The involvement of complement in the fresh serum enhancement of killing was supported by the finding, by immunofluorescence, of surface C3 on Mf after incubation in fresh OS.

Indirect hemagglutination test for diagnosis of canine filariasis.

Four kinds of Dirofilaria immitis antigens, prepared from intrauterine micro-filariae (I-Mf), circulating microfilariae (C-Mf), migrating larvae and adult worms (A-Di), were assessed by indirect hemagglutination (IHA) test in terms of immunological specificity and sensitivity. The highest specificity and sensitivity were observed in phosphate buffered saline (PBS) extract of I-Mf among these antigens. In contrast, PBS extract of C-Mf was found to have extremely low IHA antigenicity. Cross reactions between D. immitis and some intestinal parasites, such as Toxocara canis, Ancylostoma caninum and Trichuris vulpis, were evaluated by agglutinin absorption assay. It was revealed that no substantial cross reaction was present between I-Mf or A-Di and the above three intestinal parasites. Agglutinin absorption assay also suggested that the antigenicity of A-Di antigen differed from that of I-Mf antigen, although some common antigens were present between them. The present results indicate that I-Mf antigen is useful for IHA test in D. immitis infection in dogs.

Immunological response of dogs to Dirofilaria immitis infection (author's transl)

犬糸状虫感染に対する犬の免疫応答をマクロファージ遊走阻止(MI)試験(間接法), 間接赤血球凝集(IHA)反応, 受身皮膚アナフィラキシー反応により, 検討した. 犬糸状虫成虫抗原と子宮内ミクロフィラリア(Mf)抗原を用いたMI試験の結果, 犬糸状虫未感染犬群13頭と自然感染犬群20頭の成績は陰性であった. 犬糸状虫実験感染犬3頭(感染子虫数98～121匹)および未感染対照犬2頭の感染経過中における免疫応答の動態についても検討した.感染犬では, IHA抗体, レアギン抗体ともに実験期間を通して産生され, 特に著明な増加は, 第4脱皮期と末梢血Mf陽性時期に関連している可能性が認められた. それにもかかわらず, prepatent periodにおけるMI試験は陰性であった.

Drug therapy reviews: Clinical pharmacology and therapeutic use of antimycotic drugs

Indications, pharmacology, mechanism of action, adverse reactions, administration and dosage ot SIX antimycotic drugs (amphotericin B, flucytosine, nystatin, clotrimazole, miconazole nitrate and griseofulvin) are reviewed. The availability and cost of commercial preparations are listed. Amphotericin B is the single most effective drug against the following systemic fungal infections: blastomycosis, histoplasmosis, cryptococcosis, candidiasis, sporotrichosis, aspergillosis, mucormycosis and coccidioidomycosis. Some Candida sp are sensitive to flucytosine, but the drug IS useful only occasionally in the treatment of systemic candidal infections. Flucytosine may be effective in the treatment of Aspergillus pneumonia and meningitis, hut this drug alone is not the best treatment. Nystatin has been used topically to treat superficial candidal infections of the oral mucosa (thrush) and esophagus, and candidal stomatitis, pharyngitis and vaginitis; aerosols have been used to treat systemic aspergillosis and candidiasis. Clotrimazole. IS useful topically for Candida, Tricophyton or Microsporum skin infections, and vaginally tor vaginal candidiasis. Intravenous miconazole is used most commonly against Coccidioides immitis infections involving pulmonary, osseous and meningeal sites; topically, miconazole has the same Uses as clotrimazole. Griseofulvin is most effective for tinea and ringworm infections caused by Tricophyton sp and Microsporum sp. No other antiinfective drug causes toxic reactions as often as amphotericin B; however, the drug does have unique uses that often outweigh its risks. Flucytosine may depress the bone marrow and cause leukopenia, neutropenia and thrombocytopenia. Nystatin causes few adverse reactions; systemic absorption is minimal. There are few side effects with topical use of Clotimazole. Phlebitits often occurs after i.v administration of miconazole nitrate. Griseofulvin produces few adverse effects

Presumed Dirofilaria immitis infections in natural mosquito populations of Connecticut.

During the summers of 1976 and 1977. 3294 vertebrate host-seeking mosquitoes were captured by the human-bait method in areas where dog heartworm was known to occur. Following dissections of ovaries and other internal organs. specimens were age-graded by the Polovodova method and examined for filarial worms. “Sausage-stage,” late 2nd-stage, and (or) L3-stage filarial larvae were found in 46 (1.4%) of Aedes canadensis, Ae. excrueians, Ae. stimulans, Ae. sollieitans, Ae. vexans, and Psorophora ferox. Filarial worms occurred in nulliparous as well as parous mosquitoes. Although Ae. canadensis appears to be an important potential vector, the complete development of Dirofilaria immitis to the infectious stage in 3 other mosquito species suggests that mosquitoes of several species are probably involved in dog heartworm transmission in the northeastern United States.

Dirofilaria immitis: Experimental Infections in the Ferret (Mustela putorius furo)

The ferret, Mustela putorius furo, was found to be susceptible to Dirofilaria immitis infection when exposed to low (14) or high (280-420) numbers of infective larvae harvested from Aedes aegypti. Eight ferrets (half of them cortisonized) were inoculated subcutaneously with 14 larvae each. All of them were subsequently found to harbor D. immitis in the heart, and all but one of them had worms of both sexes. Six of these ferrets were examined for microfilaremia at 31 to 35 weeks after inoculation; 3 were positive (one observed only at postmortem examination) and there was evidence that fertilization of female worms had occurred in one other. Females up to 25.5 cm and males up to 16.0 cm were recovered. There was no evidence that the cortisonization of some ferrets had affected the infections. Both male and female ferrets became infected. Four cortisonized ferrets were inoculated with 280 or 420 larvae of D. immitis (divided equally between subcutaneous and intraperitoneal routes). All of them died 16 to 18 weeks after inoculation, yielding 102 to 125 immature D. immitis. In these lethal infections, worms were recovered from the heart and adjoining vessels, and also from vascular and extravascular sites throughout the body.

Immunodiagnosis of parasitic zoonoses: comparative efficacy of three immunofluorescence tests using antigens purified by affinity chromatography

Three immunofluorescent antibody assays were developed during this study: the direct (DFAT) and indirect (IFAT) fluorescent antibody tests using frozen worm sections, and the cyanogen bromide indirect fluorescent antibody test (CNBr-IFAT) using helminth antigens purified by affinity chromatography bound on to commercially prepared CNBr-Sepharose 4B beads. Purified antigens used in the CNBr-IFAT gave greater specificity and sensitivity than either the DFAT or IFAT. Dirofilaria immitis, Toxocara canis, Angiostrongylus cantonensis and Ascaris lumbricoides infections were studied in natural and zoonotic hosts and in rabbits immunized with antigens prepared from these parasites. In addition, a serological survey of Aboriginal Australians from Queensland was made.

Physiological basis of host susceptibility of Florida mosquitoes to Dirofilaria immitis

Young females of seven species of Florida mosquitoes were fed a meal of dog blood infected with Dirofilaria immitis to repletion to study the physiological mechanisms which control susceptibility and resistance in these mosquitoes. Various species of mosquitoes showed different grades of susceptibility. In all mosquitoes, microfilariae reached the midgut immediately after ingestion. Their movement from midgut to the specific host tissue—the Malpighian tubules—was either facilitated or inhibited depending on the presence or absence of anticoagulins in the salivary glands of these mosquitoes. In Anopheles quadrimaculatus, Aedes taeniorhynchus, and Aedes sollicitans, microfilariae move freely from the midgut to the Malpighian tubules, because of the presence of substantial amounts of anticoagulins in their salivary glands, and 30 to 60 mf/female developed normally to an infective stage. Very few microfilariae reached the tubules of Mansonia titillans as most of them were defaecated within a very short time after ingestion. In Aedes aegypti, Culex nigripalpus, and Culex pipiens quinquefasciatus movement of microfilariae from the midgut to the Malpighian tubules was obstructed by the coagulation of blood soon after ingestion. Coagulation of blood was followed by formation of oxyhaemoglobin crystals in C. nigripalpus and C. p. quinquefasciatus. It is suggested that secretions from symbiotic bacteria in the midgut of these mosquitoes lyse ingested red blood cells, and the released haemoglobin is oxidized to oxyhaemoglobin crystals which hinder the further movement of microfilariae and kill them. Microfilariae developed normally in A. quadrimaculatus, thus making them potentially the most susceptible mosquitoes, even though these mosquitoes did not survive to be effective potential vectors. A few microfilariae or their later developmental stages were melanized in the tubules of most A. sollicitans and A. taeniorhynchus, but the numbers of melanized stages were too few to affect the vectoring potentials of these species. In 20 per cent of A. sollicitans, 60 per cent of M. titillans, and ca. 80 per cent A. aegypti substantial numbers of the microfilariae after reaching the Malpighian tubules did not advance beyond the prelarval stage, and very few microfilariae developed successfully in the remaining mosquitoes. Very few microfilariae reached the Malpighian tubules of a small percentage of C. nigripalpus and C. p. quinquefasciatus and developed normally. The vectoring potentials of A. sollicitans, M. titillans, A. aegypti, and both Culex species were greatly hampered. These studies suggested that host-specificity of mosquitoes to D. immitis infection is controlled by the presence or absence of secondary physiological factors in their digestive tracts or in the Malpighian tubules.

Filariasis in Coyotes from Kansas and Colorado

Prevalence of Dirofilaria immitis in a sample of 133 coyotes (Canis latrans) from Kansas and Colorado was determined during winter, 1972. Adult heartworms were found in 11 of 133 coyotes examined (8%). Among coyotes from northeastern Kansas, 9 of 111 (8% ) were infected with D. immitis. Neither of 2 coyotes from central Kansas was infected, but 2 of 20 eastern Colorado coyotes (10%) were infected with D. immitis. The highest percentage (30%) of D. immitis infection occurred among coyotes aged 5 to 6 years, although 3 yearling coyotes were infected. Single sex infections with D. immitis occurred in 5 of 11 coyotes, and maximum worm burden was 12. Based on local bounty records for 1949 to 1969, the average estimated number of adult coyotes in 450 sq. miles of Leavenworth County, Kansas, was 250 or 1 adult coyote for each 1.8 sq. mile. In any year approximately 20 adult coyotes in the county would contain 1 or more adult D. immitis; however, only 10 of these 20 coyotes would contain both sexes of D. immitis and would be capable of producing microfilariae. In Leavenworth County coyotes infected with D. immitis were estimated to comprise less than 1% of infected canine hosts. Although the canine heartworm, Dirofilaria immitis (Leidy), is most often reported in domestic dogs, it has also been found in domestic cats (Bernard, 1970) and wild canines. Faust et al. (1941) reported the occurrence of D. immitis in the wolf (Canis floridanus) in Louisiana, and Erickson (1944) reported it in a red fox (Vulpes fulva) from New York. Gier and Ameel (1957) found heartworms in 10 coyotes (Canis latrans) from Kansas. Unfortunately most published reports of D. immitis in wild mammals only represent the occurrence of an isolated infection (Hirth and Nielsen, 1966), and surveys for heartworms in wild mammals have been infrequent. Few published surveys of wild mammal parasites have included an estimate of the mammal population size as did Gier (1957), and wild mammal surveys have not often been carried out in an area from which comparative data on the prevalence of D. immitis in domestic dogs has also been available (Schlotthauer, 1964; Schlotthauer and Griffiths, 1964). A number of authors have concluded that wild mammal populations are not significant as reservoirs of D. immitis infection (Schlotthauer, 1964; Otto, 1969). This conclusion seems to be based on the absence of any reported high rate of D. immitis infection among wild mammals surveyed. Because published Received for publication 19 August 1974. * Present address: Department of Zoology, University of Michigan, Ann Arbor, Michigan 48104. surveys of heartworm in wild mammals are so scarce, however, this conclusion should be supported with additional data. The availability of coyote carcasses in northeastern Kansas permitted study of the occurrence of D. immitis in 133 coyotes (Canis latrans) necropsied during winter 1972. Comparable data on the prevalence of heartworm in domestic dogs from northeastern Kansas have been reported previously (Graham, 1974). MATERIALS AND METHODS Coyote carcasses were obtained for examination from a fur buyer in northeastern Kansas through whose cooperation coyotes were sorted according to area of origin when purchased from hunters. Of the 133 coyotes examined the majority (111) came from 4 counties in northeastern Kansas: Leavenworth, Jefferson, Douglas, and Atchison. Two coyotes came from Saline County in central Kansas. Although the counties of origin could not be determined, the remaining 20 coyotes came from eastern Colorado. Coyote sex was recorded, and age was determined according to dental wear pattern (Gier, 1957). The right auricle and ventricle and their associated blood vessels were examined for adult heartworms, but the lungs were not examined separately. Some heartworms might have undergone postmortem migration into the lungs and been overlooked, and very small heartworms might have been missed in the large masses of frozen blood frequently found in the hearts. The prevalence of D. immitis in coyotes could therefore be somewhat higher than indicated by the examinations. When an animal was found infected with D. immitis, the heart and filarial worms were removed and pre-