Open Veterinary Journal, (2025), Vol. 15(8): 3378-3379

Letter to the Editor

10.5455/OVJ.2025.v15.i8.1

Commentary on the molecular and morphological identification of microfilariae in domestic chickens: Future perspectives

Nathkapach Kaewpitoon Rattanapitoon^*, Chutharat Thanchonnang and Schawanya Kaewpitoon Rattanapitoon

Parasitic Disease Research, FMC Medical Center of Thailand, Nakhon Ratchasima, Thailand

*Corresponding Author: Nathkapach Kaewpitoon Rattanapitoon, Parasitic Disease Research, FMC Medical Center of Thailand, Nakhon Ratchasima, Thailand. Email: nathkapach.ratt [at] gmail.com

Submitted: 27/05/2025 Revised: 14/07/2025 Accepted: 20/07/2025 Published: 31/08/2025

---

ABSTRACT

This letter is a response to the recent article on the morphological and molecular identification of microfilariae in chickens in Northeastern Thailand. We recommend the authors for their important contributions to avian parasitology and offer additional perspectives on molecular techniques, sex-based infection patterns, pathological implications, and host specificity. Emphasis is placed on potential improvements in diagnostic methods and suggestions for future research directions to enhance understanding of filarial infections in poultry and their broader One Health relevance.

Keywords: Eufilaria, Filariasis, Backyard chickens, Molecular detection, Avian parasites, Host specificity, One Health.

---

Dear Editor,

We would like to express our appreciation for the study by Srikacha and Pornpanom (2025), which provided essential data on the prevalence and diversity of filarial nematodes in backyard chickens in Northeastern Thailand. This study expands our understanding of avian filariasis in domestic hosts, a field underrepresented in Southeast Asia.

We respectfully offer several comments that may complement the findings and guide future research.

The detection of Eufilaria sp. using COX1-based molecular methods is notable. While COX1 is widely accepted, integrating full mitochondrial genome sequencing, as demonstrated by Hayashi et al. (2024), may improve species-level resolution and phylogenetic clarity.

The disparity between the number of microscopy-positive and PCR-positive samples (22 vs. 7) indicates potential issues beyond primer sensitivity. Factors such as sample preservation, PCR inhibitors, or infection stage may influence the detection yield, as noted by Hamer et al. (2013).

The higher infection rates observed in male chickens raise interesting questions. Similar sex-related trends have been linked to behavioral and hormonal factors in wild birds (Chagas et al., 2021). Longitudinal studies could clarify these dynamics in poultry populations.

Although no clinical signs were observed, previous studies (e.g., Sekiguchi et al., 2018; Hayashi et al., 2024) have linked low microfilarial burdens with vascular lesions and respiratory effects. Including pathological assessments in future studies—especially in high-prevalence regions such as Kalasin—would be valuable.

The identification of Eufilaria in chickens, a genus usually associated with wild birds (Granath, 1981; Binkienė et al., 2021), raises questions about host adaptation and interspecies transmission. Given the diverse vector fauna of Thailand, further research is warranted.

We recommend the authors for highlighting this neglected group of parasites and hope that these reflections contribute to the ongoing discussion and future research.

---

References

Binkienė, R., Chagas, C.R.F., Bernotienė, R. and Valkiūnas, G. 2021. Molecular and morphological characterization of three new avian species, Onchocercidae (Nematoda), with emphasis on circulating microfilariae. Paras. Vectors 14, 137.

Chagas, C.R.F., Binkienė, R. and Valkiūnas, G. 2021. Description and molecular characterization of two avian blood parasite species, with remarks on the circadian rhythms of avian hematozoa infections. Animals 11(12), 3490.

Granath, W.O. 1981. Eufilaria hibleri sp. n. (Nematoda: Filarioidea) isolated from the common grackle (Quiscalus quiscula versicolor). Proc. Helminthol. Soc. Wash. 48, 17–23.

Hamer, G.L., Anderson, T.K., Berry, G.E., Makohon-Moore, A.P., Crafton, J.C., Brawn, J.D., Dolinski, A.C., Krebs, B.L., Ruiz, M.O., Muzzall, P.M., Goldberg, T.L. and Walker, E.D. 2013. Prevalence of filarioid nematodes and trypanosomes in American robins and house sparrows, Chicago USA. Int. J. Parasitol. Parasites Wildl. 2(4), 42–49; doi:10.1016/j.ijppaw.2012.11.005

Hayashi, N., Hosokawa, K., Yamamoto, Y., Kodama, S., Kurokawa, A., Nakao, R. and Nonaka, N. 2024. A filarial parasite potentially associated with the health burden on domestic chickens in Japan. Sci. Rep. 14, 6316.

Sekiguchi, M., Nonaka, N., Adachi, M., Sekiya, T. and Yamamoto, Y. 2018. Avian filariasis in backyard chickens in Japan. Avian Dis. 62, 326–329.

Srikacha, N. and Pornpanom, P. 2025. Morphological and molecular characterization of microfilariae in chickens (Gallus gallus domesticus) in Northeastern Thailand. Open Vet. J. 15(5), 2030–2038.