Determining vector competence of Aedes aegypti from Ghana in transmitting dengue virus serotypes 1 and 2

Michael Amoa-Bosompem,Cuong Chi Tran,Phong Vu Tran,Shiroh Iwanaga,Yasuhiro Shoji ,Ryosuke Fujita,Kentaro Itokawa,Daisuke Kobayashi,Mitsuko Ohashi,Astri Nur Faizah,Shinji Kasai,Kyoko Sawabe,Joseph Humphrey Kofi Bonney ,Faustus Akankperiwen Azerigyik,Katsunori Murota,T Hayashi ,Yoshihide Maekawa,Samuel Dadzie,Nobuhiro Ohta ,Haruhiko Isawa

doi:10.1186/s13071-021-04728-z

Abstract

BackgroundDengue virus (DENV) is a mosquito-borne arbovirus transmitted by Aedes mosquitoes, but is not endemic in all areas where this vector is found. For example, the relatively sparse distribution of cases in West Africa is generally attributed to the refractory nature of West African Aedes aegypti (Ae. aegypti) to DENV infection, and particularly the forest-dwelling Ae. aegypti formosus. However, recent studies have shown these mosquitoes to be competent vectors within some West African countries that have suffered outbreaks in the past, such as Senegal. There is however little information on the vector competence of the Ae. aegypti in West African countries such as Ghana with no reported outbreaks.MethodsThis study examined the vector competence of 4 Ae. aegypti colonies from urban, semi-urban, and two rural locations in Ghana in transmitting DENV serotypes 1 and 2, using a single colony from Vietnam as control. Midgut infection and virus dissemination were determined by quantitative reverse transcription polymerase chain reaction (qRT-PCR), while the presence and concentration of DENV in the saliva of infectious mosquitoes was determined by the focus forming assay.ResultsThere were significant differences in the colonies’ susceptibility to virus infection, dissemination, and transmission. All examined Ghanaian mosquitoes were refractory to infection by DENV serotype 2, while some colonies exhibited potential to transmit DENV serotype 1. None of the tested colonies were as competent as the control group colony.ConclusionsThese findings give insight into the possible risk of outbreaks, particularly in the urban areas in the south of Ghana, and highlight the need for continuous surveillance to determine the transmission status and outbreak risk. This study also highlights the need to prevent importation of different DENV strains and potential invasion of new highly vector-competent Ae. aegypti strains, particularly around the ports of entry.Graphical

Highlights

Dengue virus (DENV) is a mosquito-borne arbovirus transmitted by Aedes mosquitoes, but is not endemic in all areas where this vector is found
Dengue fever is caused by the flavivirus dengue virus (DENV), which consists of four serotypes (DENV 1–4) that are phylogenetically and antigenically distinct [7,8,9]
Population assignment of Ae. aegypti colonies In confirming the lineages of the five Ae. aegypti colonies examined, 12 microsatellite loci were independently genotyped in each population by discriminant analysis of principal components (DAPC) and compared to previously reported genotypes of Ae. aegypti populations collected globally [25]

Summary

Introduction

Dengue virus (DENV) is a mosquito-borne arbovirus transmitted by Aedes mosquitoes, but is not endemic in all areas where this vector is found. Amoa‐Bosompem et al Parasites Vectors (2021) 14:228 dengue fever cases continues to grow; several countries in Europe and Africa have recently reported cases for the first time—imported or possibly locally transmitted— while other countries like Japan are experiencing outbreaks after a period of > 70 years with no reported cases [2,3,4,5,6]. On the other hand, typically records hundreds of cases, which may increase to thousands in a severe outbreak, but still significantly lower than those of Asia and the Americas [7, 10] These apparent differences in outbreak incidence and intensity have been attributed to many factors, including the role of the Aedes vector

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