Prevalence of trypanosomes, salivary gland hypertrophy virus and Wolbachia in wild populations of tsetse flies from West Africa

Background: Tsetse flies are vectors of African trypanosomes, protozoan parasites that cause sleeping sickness (or human African trypanosomosis) in humans and nagana (or animal African trypanosomosis) in livestock. In addition to trypanosomes, four symbiotic bacteria Wigglesworthia glossinidia, Sodalis glossinidius, Wolbachia, Spiroplasma and one pathogen, the salivary gland hypertrophy virus (SGHV), have been reported in different tsetse species. We evaluated the prevalence and coinfection dynamics between Wolbachia, trypanosomes, and SGHV in four tsetse species (Glossina palpalis gambiensis, G. tachinoides, G. morsitans submorsitans, and G. medicorum) that were collected between 2008 and 2015 from 46 geographical locations in West Africa, i.e. Burkina Faso, Mali, Ghana, Guinea, and Senegal. Results: The results indicated an overall low prevalence of SGHV and Wolbachia and a high prevalence of trypanosomes in the sampled wild tsetse populations. The prevalence of all three infections varied among tsetse species and sample origin. The highest trypanosome prevalence was found in Glossina tachinoides (61.1%) from Ghana and in Glossina palpalis gambiensis (43.7%) from Senegal. The trypanosome prevalence in the four species from Burkina Faso was lower, i.e. 39.6% in Glossina medicorum, 18.08%; in Glossina morsitans submorsitans, 16.8%; in Glossina tachinoides and 10.5% in Glossina palpalis gambiensis. The trypanosome prevalence in Glossina palpalis gambiensis was lowest in Mali (6.9%) and Guinea (2.2%). The prevalence of SGHV and Wolbachia was very low irrespective of location or tsetse species with an average of 1.7% for SGHV and 1.0% for Wolbachia. In some cases, mixed infections with different trypanosome species were detected. The highest prevalence of coinfection was Trypanosoma vivax and other Trypanosoma species (9.5%) followed by coinfection of T. congolense with other trypanosomes (7.5%). The prevalence of coinfection of T. vivax and T. congolense was (1.0%) and no mixed infection of trypanosomes, SGHV and Wolbachia was detected. Conclusion: The results indicated a high rate of trypanosome infection in tsetse wild populations in West African countries but lower infection rate of both Wolbachia and SGHV. Double or triple mixed trypanosome infections were found. In addition, mixed trypanosome and SGHV infections existed however no mixed infections of trypanosome and/or SGHV with Wolbachia were found

Sentinel laboratory compliance with best practices in Burkina Faso’s antimicrobial resistance surveillance network

Background: Standardising procedures is the best way to harmonise and strengthen the quality of laboratory-based antimicrobial resistance surveillance. Since 2018, Burkina Faso has developed and disseminated the national manual of procedures for performing antibiotic susceptibility tests in sentinel laboratories within its national antimicrobial resistance surveillance network. Objective: Our study aimed to assess these sentinel laboratories’ compliance with good practices for antibiotics susceptibility tests. Methods: Four teams evaluated the antimicrobial resistance sentinel sites laboratories throughout Burkina Faso from 19 to 28 September 2022. Eighteen out of 19 sentinel laboratories were evaluated. A four-member technical committee designed and validated the evaluation tool composed of three Microsoft Excel sheets. The evaluation emphasised quality controls for culture media, antibiotic discs and compliance with antimicrobial susceptibility testing procedures by the laboratories. Excel software was used for data recording and graphs and table design. The free R software version 4.2.0 was used for descriptive statistics. An overall score below 80% was considered noncompliance. Results: Most (83.33%) of the sentinel laboratories conducted at least one quality control activity for culture media, and 66.67% conducted at least one quality control activity for antibiotic discs. Over three-quarters (76.47%) of the laboratories were more than 80% compliant with the modified Kirby Bauer antimicrobial susceptibility testing method. Conclusion: The evaluation revealed the noncompliance of sentinel laboratories with the national procedure manual, particularly in the quality control component. What this study adds: This study has provided baseline data on the sentinel laboratories’ compliance with the national antimicrobial susceptibility testing procedures manual, particularly in areas performing quality control checks or meeting quality indicators for culture media and antibiotic discs

A non-destructive sugar-feeding assay for parasite detection and estimating the extrinsic incubation period of Plasmodium falciparum in individual mosquito vectors

Despite its epidemiological importance, the time Plasmodium parasites take to achieve development in the vector mosquito (the extrinsic incubation period, EIP) remains poorly characterized. A novel non-destructive assay designed to estimate EIP in single mosquitoes, and more broadly to study Plasmodium–Anopheles vectors interactions, is presented. The assay uses small pieces of cotton wool soaked in sugar solution to collect malaria sporozoites from individual mosquitoes during sugar feeding to monitor infection status over time. This technique has been tested across four natural malaria mosquito species of Africa and Asia, infected with Plasmodium falciparum (six field isolates from gametocyte-infected patients in Burkina Faso and the NF54 strain) and across a range of temperatures relevant to malaria transmission in field conditions. Monitoring individual infectious mosquitoes was feasible. The estimated median EIP of P. falciparum at 27 °C was 11 to 14 days depending on mosquito species and parasite isolate. Long-term individual tracking revealed that sporozoites transfer onto cotton wool can occur at least until day 40 post-infection. Short individual EIP were associated with short mosquito lifespan. Correlations between mosquito/parasite traits often reveal trade-offs and constraints and have important implications for understanding the evolution of parasite transmission strategies