Buffy coat smear or Knott's test: which to choose for canine microfilaria screening in field studies?

Marcos, Ricardo; Pereira, Cristina Camargo; Santos, Marta; Luzzago, C.; Lauzi, Stefania; Maia, João P.; Faustino, Augusto; Puente-Payo, Pablo

doi:10.1111/vcp.12321

Cited by 13 publications

(13 citation statements)

References 15 publications

(42 reference statements)

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“…Two microhematocrit tubes were centrifuged for 6 min at 14,000 rpm to determine Hct using a micro-capillary reader (±0.5%). Additionally, buffy coat smears obtained from spun microhematocrit tubes were examined microscopically to check for microfilaria (42). Blood smears were prepared, dried, fixed in methanol, and stained with Wright-Giemsa (Henry Schein Animal Health, Dublin, Ohio 43017) for manual white blood cell differential counts and to screen for hemoparasites.…”

Section: Methodsmentioning

confidence: 99%

Comparative Health Assessments of Alaskan Ice Seals

et al. 2019

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Bearded (Erignathus barbatus), ringed (Pusa hispida), spotted (Phoca largha), and ribbon (Histriophoca fasciata) seals rely on seasonal sea-ice in Arctic and sub-Arctic regions. Many aspects of the biology and physiology of these seals are poorly known, and species-typical health parameters are not available for all species. Such information has proven difficult to obtain due to the challenges of studying Arctic seals in the wild and their minimal historic representation in aquaria. Here, we combine diagnostic information gathered between 2000 and 2017 from free-ranging seals, seals in short-term rehabilitation, and seals living in long-term human care to evaluate and compare key health parameters. For individuals in apparent good health, hematology, and blood chemistry values are reported by the source group for 10 bearded, 13 ringed, 73 spotted, and 81 ribbon seals from Alaskan waters. For a smaller set of individuals handled during veterinary or necropsy procedures, the presence of parasites and pathogens is described, as well as exposure to a variety of infectious diseases known to affect marine mammals and/or humans, with positive titers observed for Brucella, Leptospira, avian influenza, herpesvirus PhHV-1, and morbillivirus. These data provide initial baseline parameters for hematology, serum chemistries, and other species-level indicators of health that can be used to assess the condition of individual seals, inform monitoring and management efforts, and guide directed research efforts for Alaskan populations of ice-associated seals.

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Section: Methodsmentioning

confidence: 99%

Comparative Health Assessments of Alaskan Ice Seals

et al. 2019

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“…The BCM has been known and extensively used in human medicine [45,47,48,75,76]. In veterinary medicine, it was mainly applied for examination of mammalian blood samples, with a focus on diagnostics of parasitic infections with zoonotic potential [47,52,53,[77][78][79]. This tool has been insufficiently applied in avian parasitology in wildlife [9,[58][59][60][61].…”

Section: Discussionmentioning

confidence: 99%

“…The method is based on blood centrifugation and the resulting separation of blood cells and parasites in different layers [45]. It has been commonly used in parasitology, particularly for detection of Trypanosoma species and microfilariae in humans [46][47][48] and domestic animals [49][50][51][52]. A similar technique was also used to diagnose apicomplexan parasites in humans such as Babesia spp.…”

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confidence: 99%

The buffy coat method: a tool for detection of blood parasites without staining procedures

et al. 2020

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Background: Blood parasites belonging to the Apicomplexa, Trypanosomatidae and Filarioidea are widespread in birds and have been studied extensively. Microscopical examination (ME) of stained blood films remains the gold standard method for the detection of these infections in birds, particularly because co-infections predominate in wildlife. None of the available molecular tools can detect all co-infections at the same time, but ME provides opportunities for this to be achieved. However, fixation, drying and staining of blood films as well as their ME are relatively time-consuming. This limits the detection of infected hosts during fieldwork when captured animals should be released soon after sampling. It is an obstacle for quick selection of donor hosts for parasite experimental, histological and other investigations in the field. This study modified, tested and described the buffy coat method (BCM) for quick diagnostics (~ 20 min/sample) of avian blood parasites. Methods: Blood of 345 birds belonging to 42 species was collected, and each sample was examined using ME of stained blood films and the buffy coat, which was examined after centrifugation in capillary tubes and after being transferred to objective glass slides. Parasite detection using these methods was compared using sensitivity, specificity, positive and negative predictive values and Cohen's kappa index. Results: Haemoproteus, Leucocytozoon, Plasmodium, microfilariae, Trypanosoma and Lankesterella parasites were detected. BCM had a high sensitivity (> 90%) and specificity (> 90%) for detection of Haemoproteus and microfilariae infections. It was of moderate sensitivity (57%) and high specificity (> 90%) for Lankesterella infections, but of low sensitivity (20%) and high specificity (> 90%) for Leucocytozoon infections. Trypanosoma and Plasmodium parasites were detected only by BCM and ME, respectively. According to Cohen's kappa index, the agreement between two diagnostic tools was substantial for Haemoproteus (0.80), moderate for Lankesterella (0.46) and fair for microfilariae and Leucocytozoon (0.28) infections. Conclusions: BCM is sensitive and recommended as a quick and reliable tool to detect Haemoproteus, Trypanosoma and microfilariae parasites during fieldwork. However, it is not suitable for detection of species of Leucocytozoon and Plasmodium. BCM is a useful tool for diagnostics of blood parasite co-infections. Its application might be extended to studies of blood parasites in other vertebrates during field studies.

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“…Compared with the Ag test, the microfilaria test has lower sensitivity, with 20% of heartworm-infected dogs not being microfilaremic [ 21 ]. Microfilaria testing can be performed using direct blood smear, buffy coat smear, millipore filtration, or the modified Knott test [ 22 ]. The latter is suggested in the AHS guidelines, but since not all hospitals in this study had the ability or equipment to do the modified Knott test, we chose the direct blood smear method with 0.5 mL blood.…”

Section: Discussionmentioning

confidence: 99%

Prevalence and epidemiology of canine and feline heartworm infection in Taiwan

Tan

Hung

2017

Parasites Vectors

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Background: Heartworm, Dirofilaria immitis, has long been recognized in Taiwanese dogs but feline heartworm infection has been largely overlooked by veterinarians and pet owners. The main goal of this study was to determine the prevalence and epidemiology of canine and feline heartworm infection in Taiwan. Methods: Household dogs and cats were selected from 103 veterinary hospitals in 13 cities throughout Taiwan. All animals were at least 1 year old, had received no heartworm prevention for more than 1 year, and had lived in the same city for at least 1 year. Client consent was obtained and an owner questionnaire was completed for each patient. Blood samples were collected from each canine patient and tested at each veterinary hospital for microfilariae and for circulating antigen. A positive result on either test was considered to confirm mature heartworm infection. Blood was collected from each feline patient and examined for microfilariae and a feline heartworm antigen/antibody test was performed. Descriptive statistics were used for heartworm prevalence. Multivariate logistic regression analysis was used to determine the relationships between heartworm infection and multiple risk factors. Results: A total of 2064 household dogs and 616 household cats from 103 veterinary hospitals throughout Taiwan were included in the study. The overall prevalence of canine heartworm disease was 22.8% (471/2064). In heartworm-positive dogs, 63% were both microfilaria positive and antigen positive, 35% were microfilaria negative and antigen positive, and only 2% were microfilaria positive and antigen negative. In the comparison of different life style groups, outdoor dogs (N = 797) had significantly higher heartworm prevalence rate than indoor dogs (N = 1267; p = 0.000). The heartworm prevalence rate in dogs presented with dyspnea and cough was as high as 51%. The overall prevalence of antibody-positive cats was 6.7% (41/616) and the antigen-positive prevalence rate was 3.1% (19/616). In 41 antibody-positive cats, 6 of them were also antigen-positive. In 19 antigen-positive cats, 13 of them were antibody negative. In antibody-positive and antigen-negative cats, half had no clinical signs. In antigen-positive cats, 21% had no clinical signs and only 38% had classic heartworm clinical signs (dyspnea, cough, or gastrointestinal signs).

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Buffy coat smear or Knott's test: which to choose for canine microfilaria screening in field studies?

Cited by 13 publications

References 15 publications

Comparative Health Assessments of Alaskan Ice Seals

Comparative Health Assessments of Alaskan Ice Seals

The buffy coat method: a tool for detection of blood parasites without staining procedures

Prevalence and epidemiology of canine and feline heartworm infection in Taiwan

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