Fig 1.
Chad Guinea Worm Eradication Program surveillance system (CGWEP).
The active surveillance system (Levels 1 and 2) is summarized by the figure above. The CGWEP (red boxes and red shaded area) is housed within the Chad Ministry of Public Health (MOPH) (maroon boxes).
Table 1.
Chad Guinea Worm Eradication Program surveillance levels.
Fig 2.
Villages under active surveillance in 2018.
In 2018 there were approximately 1,900 villages under active surveillance (including Levels 1 and 2). Most of these villages are distributed along the Chari River, where most human and canine cases are thought to occur.
Fig 3.
The identification of pre-emergent worms (A) is challenging because blisters and worms are often obfuscated by dog fur. The “controlled immersion” technique (B) is performed by pouring water over the lesion (left) or submerging the lesion in a bucket of water (right) to allow female adult worms to release larvae within a contained environment. This water is then safely disposed of (e.g., poured on the ground away from any water sources). The worm is finally extracted (C) by gently pulling on the worm (left) or by wrapping it around a wetted gauze. A small stick is also sometimes used to initiate the process (right). Worm extraction in people can range from one day to 2–3 weeks [7, 22], but CGWEP field staff have reported that worm extraction in dogs is typically quicker than in humans. (Photo credits: Robert Hartwig, The Carter Center.)
Table 2.
Proportion of worms contained by surveillance level, 2015–2018.
Table 3.
Proportion of infected dogs contained by surveillance level, 2015–2018.
Table 4.
Owner-reported history of previous Guinea worm-like illness in dogs infected with Dracunculus medinensis in Chad, 2015–2018.
Fig 4.
Percent of canine Guinea worm cases by region within Chad, 2015–2018.
The majority of canine cases were concentrated in Moyen Chari and Chari Baguirmi Regions for all years of study.
Fig 5.
Canine Guinea worm cases by month in Chad, 2015–2018.
Canine cases were most abundant during the months March through August; more cases were detected by the surveillance system over time.