Vietnam records first case of Dracunculus worm infection

Researchers reported the first known case of human Dracunculus worm infection in Vietnam. The case was caused by an unknown species of worm that was determined not to be the species that causes dracunculiasis, or Guinea worm disease.

Dracunculiasis is caused by the female Dracunculus medinensis worm, which was definitively ruled out as the cause of the Vietnam case, which occurred in a 23-year-old man and was detected by the Vietnamese public health surveillance system last July.

Cases of Guinea worm disease have decreased from around 3.5 million in 1986 to just 27 in 2020, according to the Carter Center, the nonprofit organization founded in 1982 by President Jimmy Carter and First Lady Rosalynn Carter, which leads international efforts to eradicate the disease.

The 27 cases occurred in just six African countries and represented a 50% decrease from the 2019 total, as eradication efforts progressed despite the COVID-19 pandemic.

Guinea worm could become the second human disease in history to be eradicated after smallpox, and the first without a vaccine.

The patient in Vietnam did not report any travel to Africa, or any other country where Guinea worm disease was previously endemic. A 1-cm section of one worm extracted from the patient was submitted to the CDC for morphological and molecular analyses, which determined it was not from the Dracunculus medinensis species, but instead from a Dracunculus species not previously reported in the GenBank database.

According to Guinea Worm Wrap-Up, a monthly publication from the Carter Center and CDC, the patient had consumed water from a nearby forest, although the report of the case in the International Journal of Infectious Diseases notes that it was not possible to determine whether the man was infected through drinking water or consuming fish.

The Carter Center noted that species of Dracunculus infect wildlife in Asia, including Dracunculus houdemeri, “which has been described from a snake in Vietnam.”

According to the case report by Pham Ngoc Thach, director of the National Hospital of Tropical Diseases in Hanoi, and colleagues, the patient received thiabendazole for 4 weeks until all hanging worms were manually removed. In all, five adult worms measuring between 1 to 2 feet were removed from the patient’s arms and legs.

Microscopic analysis of the 1-cm sample sent to the CDC determined that it was “consistent with various described reptilian Dracunculus species, although insufficient features of the adult worm were available to make a species-level diagnosis,” the researchers wrote.

References:

CDC. Parasites – Guinea worm. https://www.cdc.gov/parasites/guineaworm/biology.html. Accessed April 20, 2021.

Thach PN, et al. Int J Infect Dis. 2021;doi:10.1016/j.ijid.2021.02.018.

The Carter Center. Guinea worm cases fell 50% in 2020, Carter Center reports. https://www.cartercenter.org/news/pr/2021/guinea-worm-worldwide-cases-announcement-012621.html. Accessed April 20, 2021.

The Carter Center. Guinea worm wrap-up. https://www.cartercenter.org/news/publications/health/guinea_worm_wrapup_english.html. Accessed April 20, 2021.