International Health最新文献

Onchocerciasis is a parasitic infection caused by the filarial nematode Onchocerca volvulus and transmitted through the bites of blackflies of the genus Simulium that breed in rivers and streams. The current World Health Organisation (WHO) definition of transmission zones is limited, leaving country programmes to address challenges such as delineating transmission zones correctly, addressing blackfly migration, managing parasite and host movement, and handling cross-border transmission issues. A more data-driven approach to the practical definition of transmission zones in African countries would be advantageous. A review of the documents in the WHO Institutional Repository for Information Sharing (WHO IRIS) and using standard search engines (e.g. PUBMED, Google Scholar), has identified previously less-recognised factors that could enhance the definition and use of transmission areas in onchocerciasis areas. These guiding observations integrate historical operational, entomological, epidemiological, and ecological information with genomic aspects.

Background: Chad onchocerciasis program is conducting several onchocerciasis surveillance activities to verify the interruption of the disease transmission and deciding to stop the MDA ongoing in the country since 1998.

Methods: Entomological surveillance was conducted from June 2021 to February 2022 in the onchocerciasis persistence focus of Oulibangala, Chad.

Results: A total of 6 962 Simulium spp. Blackflies were collected near Oulibangala (n=5 871) and Kaitia (n=1181). Vector blackflies were pooled and tested for O. volvulus DNA using O-150 PCR.

Conclusions: No O. volvulus infections were detected, suggesting potential interruption of transmission in the area.

Background: Large areas in Malawi have not been treated for onchocerciasis. In order to understand whether to provide treatment in these areas of unknown onchocerciasis endemicity, the Neglected Tropical Diseases Program conducted onchocerciasis elimination mapping (OEM). Identifying and mapping of breeding sites is a prerequisite for conducting OEM and the Malawi onchocerciasis program undertook this activity.

Methods: To expedite the river surveys, the team employed a community knowledge approach using questionnaires and discussions, alongside the standard method of using topographical maps, to plan and implement river prospections for Simulium vector breeding sites.

Results: A total of 188 sites was prospected from 180 rivers, with 122 sites (67.8%) identified from community information and 58 (32.2%) from topographic maps. Out of 188 sites visited, 30 were positive for Simulium damnosum larvae/pupae and 91 were considered potential breeding sites and need to be visited in a different season for confirmation. A breeding site map for OEM areas in Malawi was developed. Prospection using the community knowledge approach lasted for 24 days (approximately eight rivers/day) compared to a previous prospection with the same team that used 12 days to prospect 25 rivers (approximately two rivers/day).

Conclusion: This demonstrates the potential of using the health system structure and community knowledge to plan and implement breeding site surveys, shortening the prospection time whilst effectively identifying fast-flowing rivers and breeding sites.

Background: Having a Simulium vector distribution map is important for all entomological and epidemiological aspects for the elimination of onchocerciasis. Developing these maps using topographic maps has some limitations such as identifying the exact locations of rapids especially with low-scale maps. This leads to breeding sites being missed during prospection. Recent efforts to map breeding sites involve the development of technologies such as satellite images, remote sensing modelling and drones. The limitation to these technologies include cost, security concerns and tree cover preventing the observation of rapids from the sky. Although community support has traditionally been used to guide entomological teams during prospection for breeding sites, community knowledge has not been an integral part in planning breeding site surveys.

Proposed approach: This paper proposes a concept of using community knowledge and health system structure for planning and implementation of breeding sites surveys. The approach uses questionnaires to gather information on fast-flowing stretches of rivers within communities. Using this information, a breeding site survey plan is developed at the national level, and reviewed and implemented at the districts and sub-districts levels using discussions, photos and videos of fast flowing rivers; and topographic maps. A working timetable is then developed which indicates areas to visit each day, maximizing time in the field and other logistics.

Conclusion: Using the health system structures and community members not only provides a rapid approach for entomological surveys, but also strengthens entomological fieldwork and fosters community engagement in vector surveillance.

Background: Defining the transmission zones for onchocerciasis is a critical first step needed in an endemic country aiming at eliminating the transmission of onchocerciasis. The process focuses on defining the geographical boundaries of areas where onchocerciasis transmission could persist with minimal influence from neighbouring regions. The use of operational transmission zones (OTZ) allows for assessment of interruption of onchocerciasis transmission with greater certainty within endemic countries.

Methods: We used available environmental, epidemiological, and entomological data on onchocerciasis in Burkina Faso from the OCP program to the present day. This information, together with field assessment allowed delineation of OTZs across the whole country.

Results: Six OTZs were identified: Comoé-Léraba, Dienkoa, Bas-Mouhoun, Volta, Boucle du Mouhoun and Gourma.

Conclusion: The delineation of the operational onchocerciasis OTZs of Burkina Faso will facilitates the implementation of futures interventions and assessment of the progress towards the disease elimination within the country and bordering regions.

The END Fund's Field Entomology Mentorship Program addresses a critical gap in trained entomologists supporting onchocerciasis elimination in Africa. Unlike conventional training, this hands-on mentorship equips early to mid-career entomologists with technical expertise in critical onchocerciasis blackfly surveillance activities. The three-year program follows a phased approach, gradually increasing mentees' independence while ensuring strong mentorship. In its inaugural year, six mentees engaged in field activities across multiple countries, contributing to the development of elimination strategies, onchocerciasis surveillance, and research projects. Mentees highlight the program's transformative impact, fostering leadership, collaboration, and strategic problem-solving. Their experiences with their mentors have strengthened national program capacity and the program is building a network of skilled experts dedicated to disease elimination. As the program evolves, mentees will take on more independent roles, ensuring sustainable expertise at the country level. This initiative underscores the importance of investing in local entomological capacity to accelerate onchocerciasis elimination efforts across Africa and other endemic countries.