Dirofilariasis pulmonar: un reto diagnóstico en la práctica clínica / Pulmonary dirofilariasis: A diagnostic pitfall in clinical practice

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Treatment and prevention of natural heartworm (Dirofilaria immitis) infections in red pandas (Ailurus fulgens) with selamectin and ivermectin.

Ten of the 48 red pandas in the Chengdu Research Base of Giant Panda Breeding, Sichuan province, China, died in 2006 after prolonged periods of depression, weight loss, and mucocutaneous membrane xanthochromia. During postmortem examination, live heartworms were found in the right cardiac ventricles and pulmonary arteries of all 10 animals. Selamectin and ivermectin were used for clinical prophylaxis in the remaining red pandas between December 2006 and November 2010. We observed a gradual decrease in morbidity and mortality during this period. As a consequence of our prophylaxis program, dirofilariosis did not occur in the remaining red pandas at Chengdu Research Base during 2010.

Acute death in heartworm-infected cats: unraveling the puzzle.

Although the acute death syndrome in feline heartworm disease is widely recognized, its pathogenesis remains a mystery. The most widely held hypothesis is that an acute anaphylactic reaction, perhaps precipitated by the death of the parasite, is the underlying cause. This study investigated the role of the physical form of antigen (Ag) in the ensuing reaction when Dirofilaria immitis-sensitized cats are challenged by intravenous (IV) administration of heartworm Ag. Healthy D. immitis-naive cats (n = 23) were sensitized using subcutaneous injections of adjuvanted D. immitis Ag administered weekly for 6 weeks. After sensitization, cats (n = 20) were anaesthetized and challenged with IV D. immitis Ag in various forms or with IV sterile 0.9% saline (n = 3). Systolic blood pressure, respiratory rate, degree of dyspnea, blood oxygen saturation, and heart rate were measured immediately before and at 10-15 min intervals after challenge until terminal apnea occurred or until euthanasia at 140 min after challenge. Blood samples were collected for complete blood count and measurements of serum serotonin immediately before and at 10, 20, and 35 min after challenge. Clinical observations were recorded as they occurred, or at 10-15 minute intervals, whichever was the more frequent. The most severe post-challenge reactions occurred in cats challenged with Ag from dead worms, live worms, and 20 ng/mL Ag. Dyspnea increased significantly after challenge in all three groups (p < 0.001; p = 0.04, and p = 0.002, respectively), and blood oxygen saturation dropped post-challenge in the Dead Worm (p < 0.001) and the 20 ng/mL Ag (p = 0.002) groups. In the 20 ng/mL Ag group, systolic blood pressure decreased (p <0.05) and respiratory rate increased (p < 0.05) post-challenge. Clinical observations included dyspnea, gastrointestinal signs (retching, defecation, or flatulence), urination, and less commonly, hemorrhage from the nostrils or anus, or cutaneous swelling (general or specifically facial). The 20 ng/mL Ag group had the highest rate of clinical signs, followed by the Dead Worm group. The most common and reliable hematologic change associated with severe clinical effects of D. immitis Ag challenge was increased hematocrit, which was statistically higher after challenge than at baseline in the Dead Worm group (p = 0.012). The model demonstrated that the physical form of heartworm Ag used for IV challenge in D. immitis-sensitized cats is an important factor for determining the characteristics of the post-challenge reaction, and the amount of exposed internal filarial Ag presented to the feline immune system may influence the severity of the response to challenge.

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.

Blood gas analysis in dogs with heartworm caval syndrome.

Blood gases and cardiopulmonary function were analyzed in 67 dogs with heartworm (HW) caval syndrome (CS) and 19 HW-free dogs. Arterial oxygen tension (PaO2) was 91.5 +/- 7.3 mmHg in the HW-free dogs, 74.9 +/- 14.3 mmHg in 46 dogs that subsequently survived surgical HW removal (surviving dogs) and 64.6 +/- 14.7 mmHg in 21 dogs which later died or were euthanatized following surgical treatment (nonsurviving dogs). PaO2 levels less than 60 mmHg were detected in 30.4% and 38.1% dogs in the surviving and nonsurviving groups, respectively. Arterial carbon dioxide tension (PaCO2) was 35.8 +/- 4.9 mmHg in the HW-free dogs, 30.7 +/- 5.6 mmHg in the surviving dogs, and 28.8 +/- 6.2 mmHg in nonsurviving dogs. PaO2 (p < 0.01) and PaCO2 were lower (p < 0.01) and the alveolar-arterial oxygen difference (AaDO2) was higher (p < 0.01) in CS dogs than in HW-free dogs. PaO2 was lower (p < 0.01) and AaDO2 was larger (p < 0.01) in the nonsurviving dogs than in the surviving dogs. Arterial blood pH and bicarbonate concentration were lower (p < 0.01) and the anion gap was larger (p < 0.01) in CS dogs than in the HW-free dogs. Serum lactic acid level in nonsurviving dogs (13.2 +/- 3.9 mmol/l) was higher (p < 0.01) than in the HW-free (1.7 +/- 0.8 mmol/l) and surviving dogs (2.7 +/- 1.8 mmol/l). The PaO2 correlated significantly with mean pulmonary arterial pressure (r = -0.65, p < 0.01), cardiac index (r = 0.44, p < 0.05) and total pulmonary resistance (r = -0.70, p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Susceptibility of Aedes albopictus mosquitoes (Oahu strain) to infection with Dirofilaria immitis.

The susceptibility of the Oahu strain of Aedes albopictus mosquitoes to infection with Dirofilaria immitis was examined to study the development of larvae in detail. Most of the developing larvae were found in the Malpighian tubules and infective larvae in the labium, indicating that Aedes albopictus Oahu strain is susceptible to the infection with D. immitis. New different patterns of development from those reported by earlier studies were observed: (i) the second-stage larvae in the thorax muscles of the mosquitoes and (ii) a small projection from the head of the sausage-form first-stage larvae.

Mortality factors in whistling swans at Lake St. Clair, Ontario.

Post mortem examinations of 31 whistling swans (Olar columbianus) collected from the Lake St. Clair marshes in the spring of 1972 indicated that lead toxicosis and filariasis (Sarconema eurycerca) were the main causes of mortality.