Immitis Antibodies Research Articles

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

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

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

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

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

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

A nationwide serological survey for Dirofilaria immitis in companion cats in the United States of America: 3.5% antibody and 0.3% antigen positivity

BackgroundFeline heartworm disease (HWD) is a complex and often misdiagnosed disease in cats, caused by the filarial nematode Dirofilaria immitis. Despite its significant impact, studies reporting the prevalence of D. immitis in apparently healthy pet cats in the USA are lacking.MethodsTo investigate feline heartworm seroprevalence in apparently healthy pet cats in the USA, serum samples (n = 2165) collected from cats across 47 states and Washington District of Columbia were analyzed for D. immitis antibody (Heska Corp.) and antigen (DiroCHEK®; Zoetis Inc.) with and without acid treatment of the samples.ResultsAntibodies to D. immitis antibodies were identified in 3.5% (76/2165) of cats from 26 states, with a significantly higher prevalence in cats from the westernmost US states (West region; 5.4%, 23/429) compared to those from the South (3.8%, 32/847), Midwest (2.7%, 9/338) and Northeast regions (2.2%, 12/551) (P < 0.04). Antigen from D. immitis was detected in 0.3% (6/2165) of cats, which was significantly lower than the antibody detection (P < 10–4), and no samples were positive for both antibody and antigen.ConclusionsThis is the largest antibody-based, nationwide serosurvey of feline heartworm in an apparently healthy cat population, and the results suggest that cats in the USA have a high risk of exposure to D. immitis-infected mosquitoes. The high nationwide prevalence (3.5%) indicates that the true prevalence of cats infected with D. immitis in the USA may be significantly underestimated. Our findings emphasize the need for increased awareness and routine testing of cats for heartworm infection, especially in non-endemic areas of the USA. Clinicians should consider appropriate use of broad-spectrum veterinary-approved parasiticides and lifestyle management in feline patients to reduce the risk of infection. Future studies should focus on evaluating the D. immitis infection status in healthy cats and developing better diagnostic assays to detect this complex infection.Graphical

First serological study of Dirofilaria immitis antibodies in household domestic ferrets (Mustela putorius furo) in southern Spain - Short communication.

Dirofilaria immitis is an endemic mosquito-borne pathogen widely spread throughout Europe as well as North and South America. Infection by D. immitis has been reported in domestic ferrets, although little is known about the occurrence and the epidemiological features of this nematode in this species. Theaim of the present retrospective study was to assess the prevalence of D. immitis antibodies using an in-house enzyme-linked immunosorbent assay specifically developed for use in ferrets. One hundred and eighty-six serum samples were obtained from the Province of Valencia (Spain), an area endemic for dirofilariosis. Of the 186 serum samples included in the study, 27 (14.51%) were classified as D. immitis seropositive and 159 samples as D. immitis seronegative. The results provide valuable information on the seroprevalence of D. immitis infection in domestic ferrets in an area endemic for this vector-borne pathogen. The presence of seropositive ferrets should be taken into account and preventive measures should be implemented, including the possibility of serological screening for the early detection of Dirofilaria antibodies as a serological marker of exposure. This is the first study that demonstrates thepresence of D. immitis exposure in ferrets in Spain. Veterinarians working in endemic areas should be aware of this infection in ferrets and their susceptibility.

Prevalence of microfilariae, antigen and antibodies of feline dirofilariosis infection (Dirofilaria immitis) in the Zaragoza metropolitan area, Spain.

Feline heartworm disease is a vector-borne parasitical disease caused by Dirofilaria immitis. Heartworm infection in dogs is prevalent in the Mediterranean countries. Information about the geographical distribution and epidemiological features of D. immitis infection in cats is scarce, particularly in urban stray cats that live within endemic regions for canine heartworm disease. The aim of the current study was to determine the seroprevalence of antigen and antibodies to D. immitis in feral cats in Zaragoza city, an endemic region of Spain. For this purpose, blood samples were examined for microfilariae using a direct blood smear technique and the modified Knott test. Two serological techniques for anti-D. immitis antibody detection (Solo Step® FH and in-house ELISA) and three different commercial antigen tests (DiroChek®, MegaELISA® DIRO Antigen and FASTest® HW) were performed. Blood samples from 250 stray cats were tested: 61 cats (24.40%) tested positive by the in-house ELISA, and 9 cats gave positive (3.6%) results with Solo Step® FH. The global seroprevalence of D. immitis in the feline population of the studied area of Zaragoza was 25.20% (63/250) including Solo Step® FH result and in-house ELISA. The blood exam for all samples was negative when evaluating for microfilariae and not a single cat was positive for antigen testing. This study demonstrates the presence of D. immitis infection in Zaragoza city. Veterinarians working in endemic areas should be aware of this infection in cats at risk and their susceptibility.

Seroprevalence of Ehrlichia spp., Anaplasma spp., Borrelia burgdorferi sensu lato, and Dirofilaria immitis in Stray Dogs, from 2016 to 2019, in Southern Italy.

Simple SummaryA retrospective study was carried out on presence of canine vector-borne disease (CVBD) antibodies in stray dogs in the Campania Region, from 2016 to 2019. Serum samples from stray dogs (n = 1023) were tested for Ehrlichia spp., Anaplasma spp., Borrelia burgdorferi sensu lato (s.l.), and Dirofilaria immitis using the SNAP® 4Dx® Plus Test Kit, (IDEXX Laboratories, Inc, Westbrook, ME, USA). The most common pathogen was Ehrlichia spp., with a percentage of positivity of 16.03%, followed by Anaplasma spp. with 7.8%. B. burgdorferi s.l. and D. immitis were observed in only 0.2% of animals.Canine vector-borne diseases (CVBD) are an important and emerging health concern for humans and animals worldwide. The purpose of the presented study was to assess, from 2016 to 2019, the seroprevalence of CVBD agents and clarify the epidemiology of tick-borne disease in stray dogs living in the Campania Region, Southern Italy. For this purpose, blood samples were collected from January 2016 to December 2019 from 1023 dogs in authorized kennels located in the five municipalities of the Campania Region. SNAP® 4DX® from IDEXX® Laboratories was used for detection of Ehrlichia spp., Anaplasma spp., Borrelia burgdorferi sensu lato (s.l.), and Dirofilaria immitis antibodies. The overall seroprevalence of CVBD in stray dogs was 19.6% (95% Confidence Intervals (CI): 17.2–22.8%; 201/1023). The most common pathogen was Ehrlichia spp., with a percentage of positivity of 16.03%, followed by Anaplasma spp. with 7.8%. B. burgdorferi s.l. and D. immitis were detected in only 0.2% of dogs; co-infection was detected in 4.5% of stray dogs tested. No link was detected between the gender, age, location, and CVBD seropositivity, except for Ehrlichia spp. for which location (Avellino Province; p = 0.007) and gender (male, p = 0.002) were risk factors for seropositivity. Our results demonstrated that animals are exposed to at least one of the four etiological agents (Ehrlichia spp., Anaplasma spp. Borrelia burgdorferi s.l., and Dirofilaria immitis) transmitted by vectors. Finally, this study highlighted the utility of serological monitoring in stray dogs, housed in kennels, given the threat posed by CVBD to animals and the zoonotic implications of these etiological agents and their vectors on human health.

Serosurvey of arthropod-borne diseases among shelter dogs in the Cumberland Gap Region of the United States

BackgroundThe Cumberland Gap Region (CGR) of the United States is a natural corridor between the southeastern, northeastern, and midwestern regions of the country. CGR has also many species of ticks and mosquitos that serve as competent vectors for important animal and human pathogens. In this study, we tested dogs from six different animal shelters in the CGR for Rocky Mountain spotted fever (RMSF), anaplasmosis, Lyme disease, canine ehrlichiosis and canine heartworm disease.ResultsSera from 157 shelter dogs were tested for antibodies to RMSF agent, Rickettsia rickettsii, using an indirect immunofluorescence assay. Sixty-six dogs (42.0%) were positive for either IgM or IgG, or both IgM and IgG antibodies to R. rickettsii. Moreover, the same set of sera (n = 157) plus an and additional sera (n = 75) from resident dogs at the same shelters were tested using the SNAP 4Dx Plus. Of 232 dogs tested, two (0.9%) were positive for antibodies to Anaplasma phagocytophilum/A. platys, nine (3.9%) were positive for antibodies to Borrelia burgdorferi, 23 (9.9%) for positive for antibodies to Ehrlichia canis/E. ewingii, and 13 (5.6%) were positive for Dirofilaria immitis antigen. Co-infection with two or more etiologic agents was detected in five animals. Three dogs had antibodies to both B. burgdorferi and E. canis/E. ewingii, and two dogs were positive for D. immitis antigen and antibodies to B. burgdorferi and E. canis/E. ewingii.ConclusionsShelter dogs in the CGR are exposed to a number of important vector-borne pathogens. Further studies are required to ascertain the roles these animals play in maintenance and transmission of these pathogens.

Efficacy and safety of a new topical formulation containing selamectin and sarolaner in the prevention of heartworm disease and the treatment of roundworm infection in cats presented as veterinary patients in Japan

The efficacy and safety of a new topical formulation containing selamectin plus sarolaner (Revolution® Plus / Stronghold® Plus, Zoetis) was evaluated for the prevention of heartworm (Dirofilaria immitis) disease and the treatment of roundworm infection in cats enrolled as veterinary patients in two field studies conducted in Japan.In the heartworm field study, 91 cats negative for D. immitis antigen and anti-D. immitis antibody were enrolled and received 9 monthly topical treatments with selamectin plus sarolaner during the period of April to December 2015. Efficacy was assessed by testing post-treatment blood samples collected 8, 12, and 15 months after initiation of treatment for the presence of D. immitis antigen and anti-D. immitis antibody. Eighty-seven cats completed the entire study and were included in the determination of efficacy. No D. immitis antigen or anti-D. immitis antibody were detected in any of the post-treatment samples.In the roundworm field study, completed in the period from April to November 2015, 64 cats with ≥100 roundworm eggs per gram (EPG) of feces were enrolled and allocated randomly in a 1:1 ratio, to receive either selamectin plus sarolaner or emodepside plus praziquantel (Profender®, Bayer). Treatments were administered topically on Days 0 and 30, and efficacy was assessed by fecal EPG counts conducted on Days 14, 30, and 60. All cats completed the entire study. At enrollment, all cats were infected with Toxocara cati. Compared to pre-treatment, geometric mean T. cati EPG counts on Days 14, 30, and 60 were reduced by >99.9% in both treatment groups.There were no treatment-related adverse events in either study. Monthly topical administration of Revolution® Plus / Stronghold® Plus providing a minimum of 6 mg/kg selamectin and 1 mg/kg sarolaner was safe and effective in the prevention of heartworm disease and the treatment of roundworm infection in cats enrolled as veterinary patients in Japan.

The Canary Islands as a model of risk of pulmonary dirofilariasis in a hyperendemic area.

We assessed the risk of human pulmonary dirofilariasis in the Canary Islands, hyperendemic for canine heartworm (Dirofilaria immitis), a zoonotic vector-borne infection. For this purpose, 1479 inhabitants were tested for anti-D. immitis antibodies. Four of the 7 islands presented high seroprevalences (from 6.2 to 12.7%), therefore high exposure to the parasite and risk of zoonotic infection. These corresponded to those islands with high canine prevalences of dirofilariasis and favourable climatic conditions for the development of mosquito vectors. The lowest prevalences (from 0 to 1.6%) were found in the desert islands and those with low canine prevalences of heartworm. Seroprevalences were very variable inside each island as well, being related to the climate and demographic factors. Human pulmonary dirofilariasis is an emerging zoonosis worldwide which frequently goes undiagnosed. Serological studies could be useful for the correct evaluation of the risk of infection among the human population, and study of the health implications of the continuous contact with the parasite in endemic areas. Sanitary authorities should be aware of the current epidemiological data, and physicians should include human dirofilariasis in the differential diagnosis of pulmonary nodules.

Dirofilaria immitis exposure status in client-owned cats with or without lower airway/lung-associated signs: case-control study in a canine heartworm-endemic area.

Objectives Heartworm-associated respiratory disease (HARD) is a recently recognised pathological manifestation in cats caused by Dirofilaria immitis exposure. This study aimed to estimate the percentage of cats at risk of developing HARD in a heartworm-endemic area (Taipei, Taiwan), and to test the correlation of heartworm exposure and the presence of lower airway/lung clinical signs (LA/L signs). Methods This was a prospective case-control study. The study design called for the enrolment of at least 80 cats with LA/L signs and at least 80 cats without such clinical signs in a 1 year period. The D immitis antibody seroprevalence of the two cohorts was compared. Results From February 2014 to January 2015, 187 client-owned cats were prospectively enrolled: 83 clinical cases with LA/L signs and 104 cats without such signs. Antibody seropositivity was approximately twice as frequent in cats with LA/L signs (13.3%) than in cats without signs (7.8%) (odds ratio [OR] 1.814); nevertheless, no statistically significant difference between the two cohorts ( P = 0.22) was found. We used 41 frozen samples from free-roaming cats to examine the possibility of different exposure rates to mosquito bites between client-owned cats and stray cats, finding the seroprevalence to be 7.5% in free-roaming cats - a result not statistically different to that in client-owned cats ( P = 0.60). Outdoor access was a significant risk factor for heartworm exposure in client-owned cats (OR 3.748; P = 0.03); however, living entirely indoors did not provide complete protection from exposure/infection. Conclusions and relevance Our results did not show statistically significant differences in antibody seroprevalence between cats with and without LA/L signs. LA/L signs were not always present under conditions of natural exposure. However, exposure to D immitis is not rare among client-owned cats, suggesting that heartworm prophylactics should be a part of routine care in all cats living in areas endemic for canine heartworm.

Moxidectin steady state prior to inoculation protects cats from subsequent, repeated infection with Dirofilaria immitis.

BackgroundInfection of cats with Dirofilaria immitis causes seroconversion on antibody tests and pulmonary pathology, often without subsequent development of adult heartworms. Consistent administration of topical 10% imidacloprid-1% moxidectin has been shown to result in sustained plasma levels of moxidectin in cats after three to five treatments, a pharmacokinetic behavior known as “steady state”.MethodsTo evaluate the ability of moxidectin at “steady state” to protect cats from subsequent infection with D. immitis, cats (n = 10) were treated with the labeled dose of topical 10% imidacloprid-1% moxidectin for four monthly treatments. Each cat was inoculated with 25 third-stage larvae of D. immitis 7, 14, 21, and 28 days after the last treatment; non-treated cats (n = 9) were inoculated on the same days, serving as infection controls. Blood samples were collected from each cat from 1 month prior to treatment until 7 months after the final inoculation and tested for antibody to, and antigen and microfilaria of, D. immitis.ResultsMeasurement of serum levels of moxidectin confirmed steady state in treated cats. Cats treated with topical 10% imidacloprid-1% moxidectin prior to trickle inoculation of D. immitis L3 larvae throughout the 28 day post-treatment period remained negative on antibody and antigen tests throughout the study and did not develop gross or histologic lesions characteristic of heartworm infection. A majority of non-treated cats tested antibody positive by 3–4 months post infection (6/9) and, after heat treatment, tested antigen positive by 6–7 months post-infection (5/9). Histologic lesions characteristic of D. immitis infection, including intimal and medial thickening of the pulmonary artery, were present in every cat with D. immitis antibodies (6/6), although adult D. immitis were confirmed in only 5/6 antibody-positive cats at necropsy. Microfilariae were not detected at any time.ConclusionsTaken together, these data indicate that prior treatment with 10% imidacloprid-1% moxidectin protected cats from subsequent infection with D. immitis for 28 days, preventing both formation of a detectable antibody response and development of pulmonary lesions by either immature stages of D. immitis or young adult heartworms.

Microscopic, serologic and molecular surveys on Dirofilaria immitis in stray dogs, Turkey

The prevalance of Dirofilaria immitis infection was evaluated in stray dogs of Erzurum, Turkey. A total of 123 whole-blood and 93 sera samples were collected from stray dogs older than 6 months were lived in animal shelter. The PCR and direct microscopic examinations were used for the detection of microfilaria and indirect-ELISA was performed for the detection of anti-D. immitis antibodies. The prevalence of D. immitis in the canine population was 8.1% by PCR, 2.1% by ELISA. In addition, microfilaria burdens of Dirofilaria sp. was 4.8% by direct blood smear examination. There was a statistical difference (P=0.05) in the prevalence between males (10.5%) and females (2.3%) by direct blood smear examination. Similarly there was a statistical difference (P<0.05) in the prevalence between males (15.8%) and females (4.7%) by PCR. Dogs belonging to the 0.5–1 years old group showed the highest prevalence than 2–4 ages group with three tests. Among the 93 samples screened by the ELISA, two samples were positive for the D. immitis antibodies. Both positive dogs with ELISA were females.

Current prevalence of Dirofilaria immitis in dogs, cats and humans from the island of Gran Canaria, Spain

The island of Gran Canaria is a hyperendemic area for canine dirofilariasis. The aim of the present study was to provide data on Dirofilaria immitis in dogs, cats, and humans on this island in 2010. The data confirms the prevalence in the overall canine population (19%), with a considerably higher prevalence (43%) in the autochthonous breed of Canarian Warren hound. The prevalence in the feline population (33%) is higher than that of the canine population, and the existence of specific D. immitis antibodies in the inhabitants of the island of Gran Canaria (12%) is confirmed. In both cats and humans, the prevalence, according to the different climate areas on the island, is related to the prevalence of D. immitis in dogs in the same area, which shows the key epidemiological role played by the canine host with regard to the transmission to other hosts of D. immitis.

Association of Wolbachia with heartworm disease in cats and dogs

Although the presence of adult Dirofilaria immitis in the pulmonary arteries and its associated arteritis and thromboembolic disease can explain some of the manifestations of canine and feline heartworm disease, the cause of other findings remains unclear. Cats with D. immitis antibodies but lacking adult parasites in the pulmonary arteries frequently develop histological lesions of the airways, resulting in a condition termed Heartworm-Associated Respiratory Disease. All D. immitis parasites harbor Wolbachia pipientis bacteria and D. immitis-infected animals can have circulating Wolbachia antibodies and pro-inflammatory Wolbachia antigens (WSP) deposited in tissues. Little is known about the role that Wolbachia plays in lung disease of animals naturally infected with D. immitis. The purpose of this study was to determine the contribution of Wolbachia to the pathogenesis of natural heartworm disease in cats and dogs. We hypothesized that animals having sufficient Wolbachia burden to be detected in lung tissue by immunohistochemistry and/or polymerase chain reaction (PCR) would have more severe pulmonary disease than those with bacteria below the limits of detection. We further hypothesized that animals that were immunoreactive to pro-inflammatory WSP would have more severe pulmonary lesions than those that were seronegative for WSP antibodies. Blood and lung tissue samples were collected from cats and dogs representing three different D. immitis infection statuses: heartworm-free, heartworm-exposed, heartworm-infected. There was a positive but weak correlation between the magnitude of D. immitis antibody titers and WSP titers in cats ( r = 0.57, p < 0.001) and in dogs ( r = 0.39, p < 0.001). Pulmonary lesions were more common in HW-infected animals than in HW-free animals. Pulmonary arteriolar occlusion was more common in HW-infected cats (57%; p = 0.003) than in HW-infected dogs (17%). Although pulmonary lesions were most common in HW-infected animals, there was no clear additive effect when either Wolbachia DNA/WSP was detected in lung tissue or when circulating Wolbachia antibodies were detected. There were no significant differences in the magnitude of pulmonary lesion scores within each HW-infection status group regardless of whether Wolbachia DNA/WSP or antibodies were detected. The relationship between Wolbachia and lung pathology in heartworm-infected animals remains to be determined. The lack of clear evidence for a role of Wolbachia in heartworm disease creates a dilemma for veterinarians treating animals in D. immitis-endemic areas. Although the indiscriminant use of antibiotics should be avoided, many clinicians prescribe doxycycline based on the favorable responses observed in human filarial diseases and promising results from the first published studies of doxycycline use in D. immitis-infected dogs.

Comparison of Coccidioides immitis serological antibody titres between forms of clinical coccidioidomycosis in horses

A retrospective study was performed to determine if there is an association between serological Coccidioides immitis antibody titres (IgG) and form/severity of coccidioidal disease in horses, and to identify trends in survival and treatment success based on the form of the disease. Data were obtained on horses with positive serological titres tested at the Coccidioidomycosis Serology Laboratory, School of Medicine, University of California, Davis from 1981 to 2004. Thirty-nine cases in which a diagnosis of coccidioidomycosis had been made were selected for inclusion. Six distinct categories were identified including abortion ( n = 6), miliary/interstitial pneumonia ( n = 6), pneumonia with thoracic effusion (pleural or pericardial) ( n = 11), disseminated ( n = 10), osteomyelitis ( n = 3) and external abscessation ( n = 3) both without pulmonary disease. Statistical differences in titre distribution were found between the abortion category and the pulmonary category ( P = 0.003), the abortion category and pneumonia with thoracic effusion ( P = 0.001), the abortion category and disseminated disease ( P = 0.001), and the pulmonary form and pneumonia with effusion ( P = 0.001). The other categories had overlapping titre results. Higher serological antibody titres seemed to be associated with a poorer prognosis for survival. Categories with the highest titres, disseminated (geometric mean titre = 104) and pneumonia with thoracic effusion (geometric mean titre = 226), were overwhelmingly fatal (19/21 known deaths) due to severe clinical disease. The categories with lower titres, abortion (geometric mean titre = 4), bone involvement only (geometric mean titre = 13) and cutaneous (geometric mean titre = 5), had a better survival rate (10/12 known survivors) and less severe clinical disease. Measurement of serological titre may be a useful diagnostic aid in establishing form and severity of disease and thus inform prognosis.

Two Enigmatic Cases of Meningitis

Two Enigmatic Cases of Meningitis

Filarial Worm Infections in Shelter Dogs and Cats from Northwestern South Carolina, U.S.A

During 1991–1992 and 1999–2000, domestic dogs (n = 611) and cats (n = 71) from animal shelters in Anderson, Pickens, and Oconee counties in northwestern South Carolina, U.S.A., were examined for the filarial heartworm, Dirofilaria immitis. For both dogs and cats, whole blood was collected and tested for microfilaria using the Modified Knott's technique. In an effort to find adult heartworms in cats only, a gross necropsy of heart, lungs, and pulmonary vessels was performed immediately after municipal euthanasia. Plasma from each cat was tested for anti–D. immitis antibodies and D. immitis antigens using in-house antibody and antigen tests. In the 1991–1992 study, 21 of 242 dogs (8.7%) were positive for D. immitis. The prevalence of heartworm in dogs increased to 12.7% (47 of 369 dogs) in 1999–2000. Another species of filarial worm, Dipetalonema reconditum, also was observed in blood samples from dogs (18 of 242 dogs [7.44%] and 28 of 369 dogs [7.6%] in 1991–1992 and 1999–2000, respectively). The prevalence of the nonpathogenic D. reconditum was not significantly different from that of D. immitis, emphasizing the importance of correct diagnosis of circulating microfilaria. Modified Knotts' and gross necropsy of cats revealed no heartworms, but 5 of 71 (7%) plasma samples were positive for heartworm antibodies.

Feline heartworm infection: serological survey of asymptomatic cats living in northern Italy

Heartworm infection is now recognized as a potential cause of serious disease in cats. Epidemiological studies indicate that in locations where the infection is endemic in the dog, cats are at risk. The aim of this work was to carry out a serological survey for the presence of anti- Dirofilaria immitis antibodies in privately owned, predominantly asymptomatic cats living in different areas of northern Italy in order to determine the distribution of the parasite and the risk of infection in this species. Serum samples from 1045 cats were evaluated using a commercial antibody (Ab) detection kit (Heska™ Solo Step™ Filariosi Felina, Heska Corporation) and results were analyzed together with information obtained by questionnaire. Results showed that 16% of all tested cats were positive for anti- D. immitis antibodies, with values ranging from 9 to 27%, depending on location. Male cats and outdoor cats appeared to be at greater risk, with a significantly higher number of positive antibody tests. The results of this study suggest that the risk of exposure with D. immitis in cats is high in northern Italy and suggest that the use of preventive drugs would be advisable in this area endemic for canine heartworm disease.

Anti-Dirofilaria immitis Antibody Levels before and after Anthelmintic Treatment of Experimentally Infected Dogs

Antibody to Dirofilaria immitis was measured in 6 dogs before and after treatment with thiacetarsamide. Antibody to microfilarial surface antigens was ascertained with an indirect fluorescent antibody assay (IFA). Various patterns of the production, or presence, of antibody to microfilarial surface antigens were observed. There was no apparent relationship between IFA results and adulticide success. Antibody to adult worm antigen was measured with an enzyme-linked immunosorbent assay (ELISA). ELISA titers increased following infection and decreased transiently at the end of the prepatent period. A marked increase in ELISA titers was noted in all dogs subsequent to an initial thiacetarsamide treatment. In general, ELISA titers returned to low levels in dogs which were successfully treated; however, in dogs with persistent infections or infections which apparently necessitated 2 adulticide treatments ELISA titers remained at pre-treatment levels during the period of observation. Since ELISA titers appeared to decrease to pre-infection levels in successfully treated dogs, the assay should have utility in subsequent antibody determinations and may permit retrospective prediction of chemotherapeutic success.