Name
#67 Exposition prophylaxis against the African eye worm: methods to prevent loiasis transmission when travelling to endemic regions
Speakers
Content Presented On Behalf Of:
International Delegates
Session Type
Poster
Date
Tuesday, March 3, 2026
Start Time
5:00 PM
End Time
7:00 PM
Location
Prince Georges Expo Hall E
Focus Areas/Topics
Trending/Hot Topics or Other not listed
Learning Outcomes
Following this presentation, the participant will be able to…
- know about the medical relevance of loiasis and key facts about the parasitic disease.
- understand the importance of exposition prophylaxis as a means to reduce the risk of loiasis transmission particularly for temporarily or intermittently exposed population groups in endemic settings.
- evaluate which of the available arthropod repellents also protect against loiasis deer fly vectors.
- know whether a combination of textile and skin repellents significantly reduces the chance to get bitten by Chrysops vectors.
- know about the medical relevance of loiasis and key facts about the parasitic disease.
- understand the importance of exposition prophylaxis as a means to reduce the risk of loiasis transmission particularly for temporarily or intermittently exposed population groups in endemic settings.
- evaluate which of the available arthropod repellents also protect against loiasis deer fly vectors.
- know whether a combination of textile and skin repellents significantly reduces the chance to get bitten by Chrysops vectors.
Session Currently Live
Description
Loiasis is a parasitic disease caused by the African eye worm Loa loa. The disease is endemic to the equatorial rain forest and adjacent areas of Central and West Africa, where it is transmitted by deer flies of the genus Chrysops. Although more than 23 million people are infected and nearly 42 million live in zones of moderate to high transmission, there are currently no established control tools available to reduce the risk of transmission in endemic regions. Despite the fact that the use of repellents has been explored against other arthropods, data on their protective efficacy against Chrysops bites in humans is lacking. Our group have established randomized controlled clinical trial protocols to assess the efficacy of four commercial skin-applied and two textile-applied repellents against Chrysops bites in a hyperendemic region in Gabon, Central Africa.
In the first trial, volunteers were randomly assigned to apply the skin repellents DEET, icaridin, citriodiol, IR3535 or an inactive control. The primary endpoint was the number of blood meal attempts by Chrysops flies. Secondary outcomes were the frequency and duration of Chrysops landings on clothing and skin. The results of the first trial are as follows: regarding the tested skin-repellents, blood meal attempts were significantly reduced by citriodiol (-50%, p=0.04) and DEET (-50%, p<0.001), but not icaridin (0%, p=0.48) and IR3535 (0%, p=0.69). Concordantly, the time spent by the fly on the skin was significantly shortened by citriodiol (-66%, p=0.02) and DEET (-46%, p<0.001), but not with icaridin (+2%, p=0.35) and IR3535 (0%, p=0.93). Conversely, the number of Chrysops landings on untreated clothing was not reduced by DEET and icaridin, while citriodiol and IR3535 treated individuals experienced a higher number of landings (p=0.005 and p=0.01, respectively).
Because our study showed a substantial but not complete protective efficacy of citriodiol and DEET against the bites of loiasis vectors, whereas icaridin and IR3535 proofed to be ineffective, a second trial has recently started to compare the efficacy of the commercial textile-repellents permethrin and icaridin alone or in combination with skin-applied citriodiol and DEET. The available results thereof will be also presented here.