Lagos bat virus in Kenya

Abstract

During lyssavirus surveillance, 1,221 bats of at least 30 species were collected from 25 locations in Kenya. One isolate of Lagos bat virus (LBV) was obtained from a dead Eidolon helvum fruit bat. The virus was most similar phylogenetically to LBV isolates from Senegal (1985) and from France (imported from Togo or Egypt; 1999), sharing with these viruses 100% nucleoprotein identity and 99.8 to 100% glycoprotein identity. This genome conservancy across space and time suggests that LBV is well adapted to its natural host species and that populations of reservoir hosts in eastern and western Africa have sufficient interactions to share pathogens. High virus concentrations, in addition to being detected in the brain, were detected in the salivary glands and tongue and in an oral swab, suggesting that LBV is transmitted in the saliva. In other extraneural organs, the virus was generally associated with innervations and ganglia. The presence of infectious virus in the reproductive tract and in a vaginal swab implies an alternative opportunity for transmission. The isolate was pathogenic for laboratory mice by the intracerebral and intramuscular routes. Serologic screening demonstrated the presence of LBV-neutralizing antibodies in E. helvum and Rousettus aegyptiacus fruit bats. In different colonies the seroprevalence ranged from 40 to 67% and 29 to 46% for E. helvum and R. aegyptiacus, respectively. Nested reverse transcription-PCR did not reveal the presence of viral RNA in oral swabs of bats in the absence of brain infection. Several large bat roosts were identified in areas of dense human populations, raising public health concerns for the potential of lyssavirus infection.

FIG. 1.

Map of Kenya, with the locations of the bat collections indicated.

FIG. 2.

Detection of viral antigen by the DFA test of frozen tissue sections of the LBV-positive E. helvum bat. Shown is viral antigen within papillae on the dorsal surface of the tongue (a) and in acinar cells of the submandibular salivary glands (b). Total magnification, ×200. The photo was by Michael Niezgoda.

FIG. 3.

Phylogenetic position of the KE131 isolate among other LBV sequences, based on the entire N gene (1,350 nt). The tree was obtained by the neighbor-joining method. Bootstrap values are presented for key nodes, and branch lengths are drawn to scale. The LBV sequences, location and date of isolation, and species are as follows: LagSA2003 (EF547451), South Africa, 2003, Epomophorus wahlbergi; Mongoose2004 (EF547453), South Africa, 2004, water mongoose; LBVSA1982 (EF547455), South Africa, 1982, E.wahlbergi; LBVSA1981 (EF547457), South Africa, 1980 to 1981, E. wahlbergi; LagSA2004 (EF547458), South Africa, 2004, E. wahlbergi; LBVZIM1986 (EF547450), Zimbabwe, 1986, cat; LBVCAR1974 (EF547449), Central African Republic, 1974, Micropteropus pusillus; LBVNIG1956 (EF547459), Nigeria, 1956, Eidolon helvum; LBVSEN1985 (EF547448), Senegal, 1985, E. helvum; and LBVAFR1999 (EF547447), France via Togo or Egypt, Rousettus aegyptiacus.

FIG. 4.

Titers of anti-LBV VNA in the sera of male and female Eidolon helvum and Rousettus aegyptiacus bats (means ± standard deviations are indicated; whiskers show 1.96 times the standard errors).

FIG. 5.

A roosting group of Eidolon helvum bats on a tree (a) and a colony of Rousettus aegyptiacus bats in a cave (b). The photos were by Ivan V. Kuzmin.