Unexpectedly high Plasmodium sporozoite rate associated with low human blood index in Anopheles coluzzii from a LLIN-protected village in Burkina Faso

• Published in: Scientific reports Vol. 8; no. 1; pp. 12806 - 10
• Main Authors: Pombi, Marco, Calzetta, Maria, Guelbeogo, Wamdaogo M., Manica, Mattia, Perugini, Eleonora, Pichler, Verena, Mancini, Emiliano, Sagnon, N’Fale, Ranson, Hilary, della Torre, Alessandra
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 24.08.2018; Nature Publishing Group
• Subjects: 45/22; 45/29; 45/77; 631/158/1469; 631/601/1466; 692/699/255/1629; Anopheles coluzzii; Aquatic insects; Blood; Data processing; Disease transmission; Humanities and Social Sciences; Insect bites; Malaria; Mosquitoes; multidisciplinary; Plasmodium; Science; Science (multidisciplinary); Systematic review; Vector-borne diseases; Vectors; Burkina Faso
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-018-31117-x

Despite the effectiveness of mass distribution of long-lasting insecticidal nets (LLINs) in reducing malaria transmission in Africa, in hyperendemic areas such as Burkina Faso the burden of malaria remains high. We here report the results of a 4-month survey on the feeding habits and Plasmodium infection in malaria vectors from a village in Burkina Faso one year following a national LLIN distribution programme. Low values of human blood index (HBI) observed in the major malaria vectors in the area ( Anopheles coluzzii : N = 263, 20.1%; An. arabiensis : 5.8%, N = 103) are consistent with the hypothesis that LLINs reduced the availability of human hosts to mosquitoes. A regression meta-analysis of data from a systematic review of published studies reporting HBI and sporozoite rates (SR) for An. gambiae complex revealed that the observed SR values ( An. coluzzii : 7.6%, N = 503; An. arabiensis : 5.3%, N = 225) are out of the ranges expected based on the low HBI observed. We hypothesize that a small fraction of inhabitants unprotected by bednets acts as a “core group” repeatedly exposed to mosquito bites, representing the major Plasmodium reservoir for the vectors, able to maintain a high risk of transmission even in a village protected by LLINs.