Evidence of new endemic foci of the foodborne helminths Angiostrongylus spp. in rats in selected communities in the Philippines

TL;DR

This study found high rates of Angiostrongylus parasites in rats in the Philippines, identifying new endemic areas and highlighting a potential public health risk.

Contribution

The first report of co-endemic Angiostrongylus spp. in Agusan del Sur, Mindanao, using molecular techniques for accurate identification.

Findings

37.3% of rats tested positive for Angiostrongylus spp., with higher prevalence in rural and sub-urban areas.

Two species, Angiostrongylus cantonensis and A. malaysiensis, were identified in the Philippines for the first time in this context.

The study reveals a wider distribution of the parasite than previously known, suggesting unseen transmission risks to humans.

Abstract

Angiostrongylus cantonensis (rat lungworm) is a zoonotic foodborne parasite causing meningoencephalitis among humans and animals. Neuroangiostrongyliasis is a globally emerging public health concern with several reported outbreaks; however, it remains neglected in the Philippines, where a lack of information on this parasite leads to underreporting and misdiagnosis. A good understanding of parasite epidemiology underpinned by accurate diagnosis is essential for treatment and control of parasitic diseases. Thus, this study aimed to determine the prevalence of Angiostrongylus spp. in rats in selected communities on Mindanao and Luzon Islands in the Philippines and provide accurate identification using molecular techniques.

A total of 126 rats were collected from selected communities in Laguna, Davao del Sur, Agusan del Sur, and Surigao del Norte. Lungs were harvested after dissection and artificially digested to isolate the parasite. DNA was extracted from the parasite, and SSU-rRNA and COI genes were amplified and sequenced.

Results showed an Angiostrongylus spp. prevalence of 37.3% in rats with significantly higher prevalence in rural and sub-urban communities. Molecular analysis revealed two species: Angiostrongylus cantonensis and A. malaysiensis. This represents the first report of co-endemic Angiostrongylus spp. in Agusan del Sur, Mindanao.

Our study revealed a high prevalence of Angiostrongylus spp. among rats from selected communities in the Philippines and identified new endemic sites, showing that the distribution of the parasite is wider than previously appreciated. Furthermore, two species were identified, which provides evidence of diverse Angiostrongylus species in the country. However, further studies are needed to investigate the pathogenicity of A. malaysiensis. Evidence of Angiostrongylus spp. in rats and the habit of eating raw or improperly prepared food in the surveyed communities may imply unseen transmission of Angiostrongylus spp. to humans. This highlights the need to establish the public health importance of angiostrongyliasis in the country starting with a surveillance scheme for this parasite.

The online version contains supplementary material available at 10.1186/s13071-025-06989-4.

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