Urban Green Spaces and Vector-Borne Disease Risk in Africa: The Case of an Unclean Forested Park in Libreville (Gabon, Central Africa)

Abstract

In Africa, vector-borne diseases are a major public health issue, especially in cities. Urban greening is increasingly considered to promote inhabitants’ well-being. However, the impact of urban green spaces on vector risk remains poorly investigated, particularly urban forests in poor hygienic conditions. Therefore, using larval sampling and human landing catches, this study investigated the mosquito diversity and the vector risk in a forest patch and its inhabited surroundings in Libreville, Gabon, central Africa. Among the 104 water containers explored, 94 (90.4%) were artificial (gutters, used tires, plastic bottles) and 10 (9.6%) were natural (puddles, streams, tree holes). In total, 770 mosquitoes belonging to 14 species were collected from such water containers (73.1% outside the forested area). The mosquito community was dominated by Aedes albopictus (33.5%), Culex quinquefasciatus (30.4%), and Lutzia tigripes (16.5%). Although mosquito diversity was almost double outside compared to inside the forest (Shannon diversity index: 1.3 vs. 0.7, respectively), the species relative abundance (Morisita–Horn index = 0.7) was similar. Ae. albopictus (86.1%) was the most aggressive species, putting people at risk of Aedes-borne viruses. This study highlights the importance of waste pollution in urban forested ecosystems as a potential driver of mosquito-borne diseases.

Mosquito-Borne Arboviruses Occurrence and Distribution in the Last Three Decades in Central Africa: A Systematic Literature Review

“…During the 2006 CHIKV outbreak in the West region of Cameroon, the persistence of anti-CHIKV IgM antibodies was reported in the local population, and entomological studies revealed high relative abundance of Aedes africanus [ 9 ]. The risk of CHIKV emergence and re-emergence in the west region of Cameroon was supported by an entomological study that showed high species richness and abundance of competent vectors in this part of the country [ 40 ]. Interestingly, a study conducted at the border between Cameroon and Gabon showed that patients coming to seek health services in Kyé-ossi in Cameroon from the neighboring town of Gabon (Bitam) were diagnosed positive with CHIKV, indicating the possibility of cross-border transmission between the two countries [ 18 ].…”

“…albopictus and the potential risk for the transmission of arboviruses [ 51 ]. The vector ecology and competence of these two vectors of DENV has already been studied in Cameroon [ 40 , 50 , 52 , 53 ].…”

“…The reports on WNV for Cameroon are scant, and it was only reported in the South West region of Cameoron, with a prevalence range of 3–82% [ 38 ]. It is clear from the study of Mayi et al [ 40 ] on vector adaptability conducted in an area bordering the South West region of Cameroon that there was high species richness and diversity of WNV-competent vectors that could represent a transmission risk in the area. However, in the town of Garoua in the North region, a study identified competent vectors of RVFV and WNV [ 58 ].…”

“… Species Countries References CMR RoC Gab CAR DRC EG Ang Cha Aedes aegypti + + + + + + + + [ 10 , 20 , 29 , 34 , 40 , 46 , 50 , 51 , 52 , 53 , 57 , 58 , 68 , 69 , 78 , 95 , 96 , 99 , 102 , 103 , 104 , 108 , 109 , 111 , 114 , 115 , 118 ...…”

Distribution and Characterization of Culicids (Diptera: Culicidae) in Two Urban Communes of Estuaire Province of Gabon

“…A report by Mourou et al 6 and Sevidzem et al 7 revealed a high frequency of mosquitoes in urban areas of Libreville. Other studies report outbreaks of some mosquito-borne arboviruses such as chikungunya and dengue in Libreville 8 .…”