Extensive Survey and Analysis of Factors Associated with Presence of Antibodies to Orthoebolaviruses in Bats from West and Central Africa

Abstract

The seroprevalence to orthoebolaviruses was studied in 9594 bats (5972 frugivorous and 3622 insectivorous) from Cameroon, the Democratic Republic of Congo (DRC) and Guinea, with a Luminex-based serological assay including recombinant antigens of four orthoebolavirus species. Seroprevalence is expressed as a range according to different cut-off calculations. Between 6.1% and 18.9% bat samples reacted with at least one orthoebolavirus antigen; the highest reactivity was seen with Glycoprotein (GP) antigens. Seroprevalence varied per species and was higher in frugivorous than insectivorous bats; 9.1-27.5% versus 1.3-4.6%, respectively. Seroprevalence in male (13.5%) and female (14.4%) bats was only slightly different and was higher in adults (14.9%) versus juveniles (9.4%) (p < 0.001). Moreover, seroprevalence was highest in subadults (45.4%) when compared to mature adults (19.2%), (p < 0.001). Our data suggest orthoebolavirus circulation is highest in young bats. More long-term studies are needed to identify birthing pulses for the different bat species in diverse geographic regions and to increase the chances of detecting viral RNA in order to document the genetic diversity of filoviruses in bats and their pathogenic potential for humans. Frugivorous bats seem more likely to be reservoirs of orthoebolaviruses, but the role of insectivorous bats has also to be further examined.

Keywords: Africa; Ebola; antibody; bats; virus.

Figure 1

Collection sites from Guinea (1, Conakry; 2, Forecariah; 3, Kindia; 4, Mamou; 5, Kissidougou; 6, Guéckedou; 7, Macenta; 8, Nzérekoré; 9, Boffa; 10, Boke; 11, Koundara; 12, Mali; 13, Siguiri and 14, Kankan), Cameroon (15, Campo; 16, Bipindi; 17, Boumnyebel; 18, Yaoundé; 19, Mbalmayo; 20, Northern Periphery Dja; 21, Djoum; 22, Mambele and 23, Tibati) and Democratic Republic of Congo (24, Boma; 25, Kimpese; 26, Zongo; 27, Kikwit; 28, Bikoro; 29, Boende; 30, Komanda and 31, Beni). The map is adapted from Pigott et al. [35]; areas closer to dark red are estimated at highest risk for orthoebolavirus spillover events, and areas in light yellow are least at risk.

Figure 2

Percentage of samples reactive to at least one orthoebolavirus antigen (less stringent and stringent cut-off) for each bat species in Guinea, Cameroon and DRC.

Figure 3

Percentage of samples reactive to GP SUDV (less stringent cut-off) and sex for the different bat species in Guinea, Cameroon and DRC.

Figure 4

Percentage of samples reactive to GP SUDV (less stringent cut-off) and age (juveniles and adults) for the different bat species in Guinea, Cameroon and DRC. Symbols (*) represent significant differences (Fisher test) between juveniles/adults with p-value < 0.0001 for Eidolon helvum, Hypsignathus monstrosus and the total.

Figure 5

Percentage of samples reactive to GP SUDV (less stringent cut-off) and age (juveniles, subadults and adults) for the different bat species in Cameroon. Symbols (*) represent significant differences (Fisher test) between juveniles/subadults, juveniles/adults and subadults/adults for Eidolon helvum (p < 0.001); between juveniles/adults (p < 0.0001) for Hypsignathus monstrosus; between juveniles/adults (p = 0.01) for Myonycteris torquata; between juveniles/subadults (p < 0.001) and juveniles/adults (p = 0.002) for Rousettus aegyptiacus; between subadults/adults (p = 0.001) for Hipposideros sp.; and between juveniles/subadults, subadults/adults and juveniles/adults (p < 0.001) for the total species.

Figure 6

Percentage of samples reactive to GP SUDV (less stringent and stringent cut-off) and (a) gestation or (b) lactation status of adult female bats in Cameroon, Guinea and DRC.