• View in gallery

    Adult male Ascaris from the patient. The size and shape (incurvated rear end and absence of genital hook) indicate that this is an adult male Ascaris. This figure appears in color at www.ajtmh.org.

  • View in gallery

    Pigs raised in the pigsty beside the patient’s farm. Swine-to-human transmission can occur via pig feces contaminated with Ascaris eggs. This figure appears in color at www.ajtmh.org.

  • 1.

    Zhu X, Chilton NB, Jacobs DE, Boes J, Gasser RB, 1999. Characterisation of Ascaris from human and pig hosts by nuclear ribosomal DNA sequences. Int J Parasitol 29: 469478.

    • Search Google Scholar
    • Export Citation
  • 2.

    Arizono N, Yoshimura Y, Tohzaka N, Yamada M, Tegoshi T, Onishi K, Uchikawa R, 2010. Ascariasis in Japan: is pig-derived Ascaris infecting humans? Jpn J Infect Dis 63: 447448.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 3.

    Miller LA et al., 2015. Ascariasis in humans and pigs on small-scale farms, Maine, USA, 20102013. Emerg Infect Dis 21: 332334.

  • 4.

    Nejsum P, Parker ED Jr, Frydenberg J, Roepstorff A, Boes J, Haque R, Astrup I, Prag J, Sørensen UFBS , 2005. Ascariasis is a zoonosis in Denmark. J Clin Microbiol 43: 11421148.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 5.

    Hoenigl M, Seeber K, Valentin T, Zollner-Schwetz I, Krause R, 2012. Pulmonary ascariasis in patients from wealthy countries: shift in epidemiology? Int J Infect Dis 16: e888.

    • Crossref
    • Search Google Scholar
    • Export Citation
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Ascariasis Resulting from Swine-to-Human Transmission in Okinawa, Japan

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  • 1 Department of Infectious, Respiratory, and Digestive Medicine, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan;
  • | 2 Department of Immunology and Parasitology, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan

A 67-year-old sugarcane farmer visited our hospital with a nematode infection (Figure 1) after having an itchy sensation in his anus the previous night and finding the nematode coming out of his anus that morning. He reported no history of overseas travel or symptoms, except weight loss of 5 kg over several months. No abnormalities were found on physical examination, in laboratory findings (including blood eosinophil counts and IgE levels), and in chest/abdominal computed tomography. No eggs were found in the stool. The nematode was identified morphologically as an adult male Ascaris. Two days after treatment with a single dose of 500 mg pyrantel pamoate, he found another 10-cm-long Ascaris worm excreted in his feces. His farm, located next to a pigsty (Figure 2), had been fertilized with manure from pigs 4 years, 2 years, and 5 months prior to the hospital visit. In addition, he often ate lunch without proper handwashing and may have acquired the infection through oral contact with his fingers contaminated with Ascaris eggs. Genome sequencing results for two polymorphic sites in the ribosomal RNA internal transcribed spacer 1 region—C and A in positions 133 and 246, respectively—were identified as those of Ascaris suum, suggesting pig origins.1,2

Figure 1.
Figure 1.

Adult male Ascaris from the patient. The size and shape (incurvated rear end and absence of genital hook) indicate that this is an adult male Ascaris. This figure appears in color at www.ajtmh.org.

Citation: The American Journal of Tropical Medicine and Hygiene 106, 6; 10.4269/ajtmh.22-0151

Figure 2.
Figure 2.

Pigs raised in the pigsty beside the patient’s farm. Swine-to-human transmission can occur via pig feces contaminated with Ascaris eggs. This figure appears in color at www.ajtmh.org.

Citation: The American Journal of Tropical Medicine and Hygiene 106, 6; 10.4269/ajtmh.22-0151

Ascariasis in humans is usually caused by Ascaris lumbricoides. However, A. suum, a parasite of pigs, has caused human infections in the United States and a few European countries.35 Although human-to-human transmission of A. lumbricoides is less likely in regions where sewerage systems are developed, swine-to-human zoonoses by A. suum can occur even in developed countries without adequate management of swine manure or control of swine parasites. This case highlights the importance of acknowledging Ascaris as an important zoonotic pathogen as well as the “One Health” approach to control infectious diseases.

ACKNOWLEDGMENTS

We thank Editage (www.editage.com) for the English language editing.

REFERENCES

  • 1.

    Zhu X, Chilton NB, Jacobs DE, Boes J, Gasser RB, 1999. Characterisation of Ascaris from human and pig hosts by nuclear ribosomal DNA sequences. Int J Parasitol 29: 469478.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 2.

    Arizono N, Yoshimura Y, Tohzaka N, Yamada M, Tegoshi T, Onishi K, Uchikawa R, 2010. Ascariasis in Japan: is pig-derived Ascaris infecting humans? Jpn J Infect Dis 63: 447448.

  • 3.

    Miller LA et al., 2015. Ascariasis in humans and pigs on small-scale farms, Maine, USA, 20102013. Emerg Infect Dis 21: 332334.

  • 4.

    Nejsum P, Parker ED Jr, Frydenberg J, Roepstorff A, Boes J, Haque R, Astrup I, Prag J, Sørensen UFBS , 2005. Ascariasis is a zoonosis in Denmark. J Clin Microbiol 43: 11421148.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 5.

    Hoenigl M, Seeber K, Valentin T, Zollner-Schwetz I, Krause R, 2012. Pulmonary ascariasis in patients from wealthy countries: shift in epidemiology? Int J Infect Dis 16: e888.

    • Crossref
    • Search Google Scholar
    • Export Citation

Author Notes

Address correspondence to Takeshi Kinjo, Department of Infectious, Respiratory, and Digestive Medicine, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan, 207 Uehara, Nishihara, Okinawa 903-0215, Japan. E-mail: t_kinjo@med.u-ryukyu.ac.jp

Disclosure: Written informed consent was obtained from the patient for publication of this article.

Authors’ addresses: Takeshi Kinjo and Jiro Fujita, Department of Infectious, Respiratory, and Digestive Medicine, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan, E-mails: t_kinjo@med.u-ryukyu.ac.jp and fujita@med.u-ryukyu.ac.jp. Hiromu Toma, Department of Immunology and Parasitology, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan, E-mail: htoma@med.u-ryukyu.ac.jp.

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