Dracunculiasis: water-borne anthroponosis vs. food-borne zoonosis

Abstract

Dracunculiasis is the first parasitic disease set for eradication. However, recent events related to the Dracunculus medinensis epidemiology in certain African countries are apparently posing new challenges to its eradication. Two novel facts have emerged: the existence of animal reservoirs (mainly dogs but also cats and baboons), and possibly a new food-borne route of transmission by the ingestion of paratenic (frogs) or transport (fish) hosts. Therefore, instead of being exclusively a water-borne anthroponosis, dracunculiasis would also be a food-borne zoonosis. The existence of a large number of infected dogs, mainly in Chad, and the low number of infected humans, have given rise to this potential food-borne transmission. This novel route would concern not only reservoirs, but also humans. However, only animals seem to be affected. Dracunculus medinensis is on the verge of eradication due to the control measures which, classically, have been exclusively aimed at the water-borne route. Therefore, food-borne transmission is probably of secondary importance, at least in humans. In Chad, reservoirs would become infected through the water-borne route, mainly in the dry season when rivers recede, and smaller accessible ponds, with a lower water level containing the infected copepods, appear, whilst humans drink filtered water and, thus, avoid infection. The total absence of control measures aimed at dogs (or at other potential reservoirs) up until the last years, added to the stimulating reward in cash given to those who find parasitized dogs, have presumably given rise to the current dracunculiasis scenario in Chad.

Unusual cutaneous manifestations of dracunculiasis: Two rare case reports

“…Recent reports of infection by ingestion of paratenic (frogs) or transport (fish) hosts support that dracunculiasis could also be a food-borne zoonosis. 5 The clinical features of dracunculiasis include mild fever, itchy rash, nausea, vomiting, diarrhea and dizziness. Nearly one year after infection, the female worm induces a blister on the skin, generally on the distal lower extremity, which ruptures.…”

“…4 The goal is global eradication of this disease by 2020. 5 The disease is not fatal but its complications may cause considerable disability in acute and chronic stages.…”

Development and validation of a quantitative PCR for the detection of Guinea worm (Dracunculus medinensis)

“…The shift from infections only in humans to an increasing number of reported infections in domestic animals and wildlife complicates the eradication of Guinea worm [ 8 , 9 , 43 ]. The current system of confirming morphologically identified/suspect nematodes using Sanger sequencing is time-consuming and presents no opportunity to be adapted for use in the field.…”

Dogs and the classic route of Guinea Worm transmission: an evaluation of copepod ingestion

“…However, the standard control strategies used for humans (e.g., filtering water, using safe water sources) cannot easily be applied to animal populations. Currently, given the unusual epidemiology compared to typical human infections, there is debate on the source of dog infections 2,3,9 . They can become infected through ingestion of infected copepods but could also become infected through ingestion of infected amphibian paratenic or fish transport hosts.…”