Detection of heartworm antigen without cross-reactivity to helminths and protozoa following heat treatment of canine serum

Gruntmeir, Jeff; Thompson, Nina M.; Long, Maureen T.; Blagburn, Byron L.; Walden, Heather Stockdale

doi:10.1186/s13071-020-04573-6

Cited by 14 publications

(22 citation statements)

References 36 publications

(70 reference statements)

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“…immitis -positive dogs, including exact worm burden and co-infection, will provide the needed insight into the value of heat treatment prior to testing for D . immitis antigen [ 13 , 46 ].…”

Section: Discussionmentioning

confidence: 99%

Multiple diagnostic tests demonstrate an increased risk of canine heartworm disease in northern Queensland, Australia

et al. 2021

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Background Canine heartworm (Dirofilaria immitis) is a life-threatening infection of dogs with a global distribution. Information on the prevalence of D. immitis and associated risk factors for canine heartworm antigen positivity—and thus disease—in Australia is scarce or outdated. The current reference method for D. immitis diagnosis in dogs is via the detection of heartworm antigen in blood using commercially available microwell-based enzyme-linked immunosorbent assays (ELISAs). Heat treatment of canine plasma prior to testing has been suggested to increase test sensitivity. The aim of the current study was to estimate the prevalence of D. immitis in dogs confined to shelters in Queensland, Australia. The impact of heat treatment on antigen test results was also assessed. Methods Blood samples (n = 166) were collected directly from dogs in seven shelters across Queensland (latitudinal span of approx. 1700 km) into EDTA blood collection tubes. A commercially available ELISA (DiroCHEK®) was used to detect canine heartworm antigen in untreated and heat-treated plasma. Whole blood was concurrently tested for the presence of microfilariae and D. immitis DNA using a modified Knott’s test and real-time PCR, respectively. Risk factors (age, gender, source, location) associated with the odds of positivity for canine heartworm were assessed using binary logistic regression models. Results A total of 16 dogs (9.6%; 95% confidence interval [CI]: 5.9–15.2%) were positive for canine heartworm based on combined test results. Heat treatment did not impact on the positivity of D. immitis antigen within samples (Cohen’s kappa = 0.98), but the optical density was significantly increased in paired plasma samples for D. immitis antigen-positive samples (Wilcoxon matched-pairs signed rank test, two-tailed P < 0.01). Location of the dog in a shelter in northern Queensland was the only risk factor significantly associated with the odds of a dog being more likely to be D. immitis antigen positive (odds ratio: 4.39; 95% CI: 1.26–13.51). All samples positive for the modified Knott’s test were also positive for D. immitis DNA by PCR. Conclusions This study demonstrated the presence of heartworm-positive dogs in shelters in Queensland, with positive animals significantly more likely to occur in northern Queensland than southern Queensland. Sustained testing for the presence of D. immitis microfilariae and antigen remain important diagnostic tools in areas with known and re-emerging canine heartworm activity. Graphical Abstract

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Section: Discussionmentioning

confidence: 99%

Multiple diagnostic tests demonstrate an increased risk of canine heartworm disease in northern Queensland, Australia

et al. 2021

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“…When coinfections are present, low Acanthocheilonema microfilaremia may be overlooked among the numerous Dirofilaria microfilariae. This co-infection scenario may also explain the reduced sensitivity of some species-specific PCR assays in cases where the ratio of one species to another is high (24,146,147) or the inability to molecularly confirm co-infections of A. reconditum and D. immitis seen following examination of the entire Knott's sediment (24). More accurate diagnosis may be achieved with more sensitive molecular assays such as single or multiplex probe-based PCR protocols (27, 57, 148), accompanied by the sequencing of amplicons as an additional confirmation.…”

Section: Pathogenicity Clinical Signs and Diagnosismentioning

confidence: 99%

“…These examples underscore the need for microfilariae testing and broad awareness of possible emerging parasites among veterinary researchers, veterinarians, and public health entities. Despite advances in molecular diagnostic tools capable of detecting and differentiating filarioid nematodes to species-level, no published D. immitis or blood microfilariae prevalence or research surveys have applied molecular tools alone or in combination with morphological identifications for screening in the US prior to 2020 for sheltered dogs (23)(24)(25) and wild canids (31), or prior to 2022 for pet dogs (26,27,32).…”

Section: Introductionmentioning

confidence: 99%

Cutaneous filarioid nematodes of dogs in the United States: Are they emerging, neglected, or underdiagnosed parasites?

Gruntmeir

Kelly²,

Ramos³

et al. 2023

Front. Vet. Sci.

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Filarioid nematodes, which are vector-borne parasites of cosmopolitan distribution, of dogs are medically important. They are represented by species in which microfilariae were found to be circulating in the bloodstream (e.g., Dirofilaria sp., Acanthocheilonema sp., and Brugia sp.) or skin-dwelling (e.g., Cercopithifilaria sp. and Onchocerca sp.). Those species whose microfilariae are detected in blood have been extensively studied, especially Dirofilaria immitis, due to their clinical importance. In recent decades, there has been an increased interest by the scientific community in filarioid nematodes whose microfilariae are detected in the skin because of the zoonotic aspect of Onchocerca lupi. In the United States (US), although D. immitis has been considered the main filarioid infecting dogs, the intense animal movement and global canine filarioid diversity may indicate that the likely presence of cutaneous filarioid nematodes is more common than previously expected. Hence, a question remains: Are these canine filarioid nematodes emerging, neglected, or simply underdiagnosed in the US? In this review, we provide an overview of pertinent information that briefly summarizes the biology of the different canine filarioid nematode species, clinical signs associated with infections, and currently available diagnostic tools using molecular and microscopy-based methods and highlight knowledge gaps where research and surveillance efforts remain necessary. The data herein presented serve as an alert to the scientific community about the importance of filarioid nematodes infecting dogs other than D. immitis. Additionally, the zoonotic potential of several filarioid species reinforces the necessity of a proper diagnosis and the need for broader surveillance to understand their diversity and distribution, to highlight the potential introduction of certain species, and mitigate their establishment in the country and new animal and human cases.

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“…Numerous researchers report cross-reactions with other dogs parasites despite indicated high specificity, e.g. Angiostrongylus vasorum , Spirocerca lupi, Taenia taeniaeformis, Toxocara canis , Toxocara cati , Dipylidium caninum and D. repens 17 – 20 ; whereas some indicate their high specificity 21 . Furthermore, worm burden and sex of the parasites impact test sensitivity 22 – 24 , making it ineffective in prepatent and occult infections.…”

Section: Introductionmentioning

confidence: 99%

Selection of new diagnostic markers for Dirofilaria repens infections with the use of phage display technology

Pękacz

Basałaj

Kalinowska

et al. 2022

Sci Rep

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Dirofilaria repens is a parasitic nematode causing vector-borne disease (dirofilariasis), considered an emerging problem in veterinary and human medicine. Although main hosts are carnivores, particularly dogs, D. repens shows high zoonotic potential. The disease spreads uncontrollably, affecting new areas. Since there is no vaccine against dirofilariasis, the only way to limit disease transmission is an early diagnosis. Currently, diagnosis depends on the detection of microfilariae in the host bloodstream using modified Knott's test or multiplex PCR. However, the efficacy of tests relying on microfilariae detection is limited by microfilariae periodic occurrence. Therefore, a new reliable diagnostic test is required. Our study aimed to select new diagnostic markers for dirofilariasis with potential application in diagnostics. We focused on single epitopes to ensure high specificity of diagnosis and avoid cross-reactivity with the other parasite infections common in dogs. Using phage display technology and 12-mer peptides library, we selected epitopes highly reactive with IgG from sera of infected dogs. Additionally, our study presents the possibility of detecting D. repens specific cell-free DNA in dogs with no microfilaria but high IgG and IgM antibody levels against parasite somatic antigen.

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Detection of heartworm antigen without cross-reactivity to helminths and protozoa following heat treatment of canine serum

Cited by 14 publications

References 36 publications

Multiple diagnostic tests demonstrate an increased risk of canine heartworm disease in northern Queensland, Australia

Multiple diagnostic tests demonstrate an increased risk of canine heartworm disease in northern Queensland, Australia

Cutaneous filarioid nematodes of dogs in the United States: Are they emerging, neglected, or underdiagnosed parasites?

Selection of new diagnostic markers for Dirofilaria repens infections with the use of phage display technology

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