Rapid Differentiation of Filariae in Unstained and Stained Paraffin-Embedded Sections by a High-Resolution Melting Analysis PCR Assay

Detecting Dirofilaria immitis: Current Practices and Novel Diagnostic Methods

The nematode Dirofilaria immitis is responsible for a vector-borne disease affecting canines and humans worldwide, known as cardiopulmonary dirofilariasis. An accurate and early diagnosis is of the utmost importance for effective disease management. While traditional microscopy-based methods remain invaluable, they have inherent limitations. Serological tests, in particular ELISA and immunochromatographic tests, are employed due to their capacity to detect D. immitis antigens, offering ease of use and diagnostic accuracy. The advent of molecular methods has the potential to enhance routine diagnostic approaches, with polymerase chain reaction (PCR) and real-time PCR (qPCR) becoming the most prevalent techniques. Despite not yet being integrated into routine diagnostics, which are predominantly based on the Knott's test and serological methods, these techniques offer significant benefits in the context of scientific research. This article proceeds to examine the potential of advanced techniques, such as high-resolution melting qPCR (HRM-qPCR), loop-mediated isothermal amplification (LAMP), droplet digital PCR (ddPCR), and microRNA (miRNA) detection, which are capable of enhanced sensitivity and early detection. The following work provides an in-depth analysis of the various diagnostic methods, emphasising the necessity of the continuous improvement and adaptation of these tools to effectively combat D. immitis. The findings underscore the importance of integrating these advanced methods into routine practice to improve detection rates and outcomes for infected animals.

Beyond Tradition: Exploring Cutting-Edge Approaches for Accurate Diagnosis of Human Filariasis

Filariasis is recognised as a global public health threat, particularly in tropical and subtropical regions. It is caused by infection with a nematode parasite of the superfamily Filarioidea, including Wuchereria bancrofti, Brugia malayi, Onchocerca volvulus, and Onchocerca lupi. Three main types of filariasis have been classified: lymphatic filariasis, subcutaneous filariasis, and serous cavity filariasis. The symptoms exhibited by individuals afflicted with filariasis are diverse and contingent upon several variables, including the species of parasite, the host's health and immune response, and the stage of infection. While many classical parasitological techniques are considered indispensable tools for the diagnosis of parasitic infections in humans, alternative methods are being sought due to their limitations. Novel tests based on host-parasite interactions offer a rapid, simple, sensitive, and specific diagnostic tool in comparison to traditional parasitological methods. This article presents methods developed in the 21st century for the diagnosis of filariasis caused by invasion from W. bancrofti, B. malayi, O. volvulus, and O. lupi, as well as techniques that are currently in use. The development of modern diagnostic methods based on molecular biology constitutes a significant advancement in the fight against filariasis.

Human gnathostomiasis: a neglected food-borne zoonosis

BACKGROUND

Human gnathostomiasis is a food-borne zoonosis. Its etiological agents are the third-stage larvae of Gnathostoma spp. Human gnathostomiasis is often reported in developing countries, but it is also an emerging disease in developed countries in non-endemic areas. The recent surge in cases of human gnathostomiasis is mainly due to the increasing consumption of raw freshwater fish, amphibians, and reptiles.

METHODS

This article reviews the literature on Gnathostoma spp. and the disease that these parasites cause in humans. We review the literature on the life cycle and pathogenesis of these parasites, the clinical features, epidemiology, diagnosis, treatment, control, and new molecular findings on human gnathostomiasis, and social-ecological factors related to the transmission of this disease.

CONCLUSIONS

The information presented provides an impetus for studying the parasite biology and host immunity. It is urgently needed to develop a quick and sensitive diagnosis and to develop an effective regimen for the management and control of human gnathostomiasis.

Molecular analysis of H&E- and Papanicolau-stained samples-systematic review

Molecular pathology allows the identification of causative agents in infectious diseases and detection of biomarkers important for prediction of disease susceptibility, diagnosis and personalized therapy. Accordingly, nucleic acid-based methods have gained a special role in clinical laboratories particularly to evaluate solid and hematological tumors. Extraction of nucleic acids is commonly performed in microdissected formalin-fixed paraffin-embedded (FFPE) or cytological samples that had been previously evaluated through the use of hematoxylin and eosin (H&E) or Papanicolau (Pap) stains, respectively. Although the effect of both stains on nucleic acids integrity has been explored by several authors, the results are not consistent and require further examination. Accordingly, the goal of this review was to assess the influence of H&E and Pap stains on DNA and RNA integrity and to address the mechanism by which each staining compromises molecular based-analysis. The analyzed studies demonstrate that H&E- and Pap-staining result in low DNA recovery and some degree of DNA fragmentation. Additionally, it is concluded that hemalum inhibits PCR by interfering with DNA extraction, preventing DNA polymerase attachment and possibly by rescuing divalent cations. Accordingly, proper sample purification and adjustment of PCR conditions are of key importance to achieve satisfactory results by PCR in H&E- and Pap-stained samples. Furthermore, although H&E results in RNA fragmentation, it is possible to perform expression analysis in H&E-stained frozen sections, using RNase-free conditions, low amounts of hematoxylin and a rapid protocol from sample collection to RNA analysis. It The effect of Pap-staining on RNA integrity remains to be determined.

Pyrosequencing Using SL and 5S rRNA as Molecular Markers for Identifying Zoonotic Filarial Nematodes in Blood Samples and Mosquitoes

BACKGROUNDS

Lymphatic filariasis is principally caused by Wuchereria bancrofti, and Brugia malayi. The other two filarial nematode species, Brugia pahangi and Dirofilaria immitis, possibly cause human zoonotic diseases.

METHODS

We propose the development of a PCR assay linked with DNA pyrosequencing as a rapid tool to identify W. bancrofti, B. malayi, B. pahangi, and D. immitis in blood samples and mosquitoes. Primers targeting the fragment of the 5S ribosomal RNA and spliced leader sequences were newly designed and developed to identify these four filarial nematodes. Analytical sensitivity and specificity were evaluated.

RESULTS

Pyrosequencing determination of nucleotide variations within 36 nucleotides for B. malayi and B. pahangi, and 32 nucleotides for W. bancrofti and D. immitis is sufficient for differentiation of those filarial nematodes, and for detection of intraspecies genetic variation of B. malayi. This analysis could detect a single B. malayi, B. pahangi, W. bancrofti, and D. immitis microfilaria in blood samples.

CONCLUSIONS

Overall, the PCR-linked pyrosequencing-based method was faster than direct sequencing and less expensive than real-time PCR or direct sequencing. This is the possibility of choice that can be applied in a high-throughput platform for identification and surveillance of reservoirs and vectors infected with lymphatic filaria in endemic areas.