Virus diversity in a winter epidemic of acute diarrhea in France

Abstract

In France, an epidemic peak of acute diarrhea is observed each winter. Previous results suggested a viral etiology for these winter epidemics. We investigated the role of enteric viruses in acute diarrhea and their molecular diversity. One hundred sixty-one patients with acute diarrhea and 45 healthy patients (controls) from the general population were given a standardized questionnaire between December 1998 and May 1999. Stool specimens were screened for group A and C rotaviruses, human caliciviruses, astroviruses, and adenovirus types 40 and 41 by reverse transcription-PCR and/or enzyme immunoassay. Virologic analysis was positive for 63 cases (39%). Caliciviruses and group A rotaviruses were the most frequent (19 and 17% of cases, respectively). Two control stool specimens were found positive for group A rotavirus, and one was found positive for astrovirus. Molecular characterization of the strains disclosed a cocirculation of P[8],G1, P[8],G4, and P[4],G2 rotaviruses; type 1, 2, 3, 4, and 8 astroviruses; and Sapporo-like and Norwalk-like human caliciviruses. These four types of viruses accounted for an attributable risk of acute diarrhea of 34.7% for the general population, under the assumption of a causal role of these viruses.

FIG. 1.

Distributions of the four viruses among the patients according to age groups. Bars indicate the following viruses: ▪, calicivirus; ▤, rotavirus; ▨, astrovirus; ▥, adenovirus types 40 and 41. The line shows the total percentage of infected patients.

FIG. 2.

Phylogenetic tree based on a 76-nucleotide region of the polymerase gene of calicivirus strains detected in France from December 1998 to May 1999. Designations consisting of the letter S followed by a number indicate the patient sample number positive for a calicivirus. GenBank accession numbers for Norwalk-like virus (NLV) strains representative of genogroup I strains were M87661 (Norwalk), L07418 (Southampton), and U04469 (Desert Shield [DS]); those for Norwalk-like virus strains representative of genogroup II strains were U07611 (Hawaii), L23831 (Snow Mountain), U22498 (Mexico), U02030 (Toronto), X86557 (Lordsdale), U46500 (Camberwell), X76716 (Bristol), and X81879 (Melksham). GenBank accession numbers for Sapporo-like virus (SLV) strains were S77903 (Sapporo/82), U95643 (Houston/86), U67858 (London/92), U95644 (Houston/90), and U73124 (Parkville).

FIG. 3.

Detected viruses. The symbols on the map of France show the following viruses: green—adenovirus types 40 and 41 (open hexagon); blue—astrovirus type 1 (open square), type 2 (open octagon containing solid square), type 3 (open triangle), type 4 (open pentagon), and type 8 (open star); yellow—human calicivirus strains Southampton (open square), H104-94J (bisected open circle), JPNNV23 (black and white circle), Hawaii (open hexagon containing solid square), Lordsdale (open triangle), Melksham (open octagon containing solid square), Mexico (open pentagon), London (open pentagon containing solid circle), and Sapporo (open square containing solid square); yellow box containing multiplication sign—nontyped; red—group A rotaviruses P[8],G1 (open square), P[8],G4 (open triangle), and P[4],G2 (open circle); red box containing multiplication sign—nontyped. The color gradations in the map indicate the incidence rates for AD as reported on the Sentinel network from December 1998 to May 1999, shown as the number of cases per 100,000 inhabitants (color key to left of map).