First molecular evidence for the presence of the canine heartworm, Dirofilaria immitis, on the island of Saipan, Northern Mariana Islands

Abstract

Blood filarioid nematodes pose a significant health impact on dogs worldwide. These parasites are mainly represented by species in the genera Dirofilaria, Brugia, and Acanthocheilonema. This study aimed to molecularly detect filarioid nematodes of dogs from Saipan, Northern Mariana Islands, using a pan-filarial PCR method. Whole blood samples (n = 443) were collected during an island-wide spay-and-neuter event. Genomic DNA was extracted, and the lysates were subjected to conventional PCR targeting a fragment of the mitochondrial cytochrome c oxidase subunit 1 gene, followed by sequencing. Filarioid nematode DNA was found in 11.2 % (8.4-14.6 %, CI 95 %) (n = 50/443) of samples. Forty-seven high-quality sequences were confirmed as Dirofilaria immitis through BLAST search and phylogenetic analysis. Sequences were 100 % identical to each other. Dog's age (p < 0.001), residing district (p < 0.001), and ownership status (p < 0.001) were statistically associated with D. immitis molecular detection. This is the first molecular detection of D. immitis in dogs of Saipan, a commonwealth of the United States, in the Western Pacific Ocean. These findings highlight the need for routine preventive chemoprophylaxis to reduce the risk of vector exposure and filarial infection.

Keywords: Dirofilariosis; Molecular diagnostics; Oceania; Vector-borne diseases.