Historical Serological Evidence of Human Exposure to Vesicular Stomatitis Virus (New Jersey and Indiana Serotypes) in Dairy Regions of Costa Rica (1999)

Abstract

Background:

Vesicular stomatitis is endemic in southern Mexico, Central America, and northern South America. The causative agent, vesicular stomatitis virus (VSV; Rhabdoviridae: Vesiculovirus), includes two serotypes—New Jersey (VSNJV) and Indiana (VSIV)—both present in Costa Rica. Transmission occurs via direct contact, fomites, and insect vectors. Occupational exposure, particularly in livestock workers, is a known risk, and high human seroprevalence has been reported elsewhere in Central America. Some cases present with a self-limited febrile illness, occasionally with vesicular lesions. No studies have assessed human VSV seropositivity in Costa Rica.

Methods:

A cross-sectional survey was conducted in two dairy cantons of Costa Rica: Poás (n = 174) and Tilarán (n = 84). Serum samples were tested for neutralizing antibodies against VSNJV and VSIV using microseroneutralization in Vero-E6 cells. The seroprevalence with 95% confidence intervals was estimated. Associations with occupation and cattle contact were evaluated using chi-square tests and relative risk (RR). No clinical data were collected, as the study was focused solely on serological evidence of exposure.

Results:

In Poás, VSNJV seroprevalence was 40.8% and VSIV 16.7%. Agricultural work was associated with higher VSNJV (RR = 2.28, p = 0.0001) and VSIV seropositivity (RR = 4.78, p = 0.0004). Direct cattle contact correlated with VSIV seropositivity (RR = 4.22, p = 0.0050). In Tilarán, VSNJV seroprevalence was 26.2% and VSIV 3.6%; only direct cattle contact was significantly associated with VSNJV (RR = 6.14, p = 0.0191). Prevalence was higher in Poás for both VSNJV (RR = 1.56, p = 0.022) and VSIV (RR = 4.67, p = 0.0028).

Conclusions:

This first report of human VSV seropositivity in Costa Rica shows a predominance of VSNJV. Higher prevalence among agricultural workers and those with cattle contact highlights occupational risk. Findings align with bovine seroprevalence and historical Central American human data, underscoring the need to consider VSV in febrile illnesses and to strengthen integrated “One Health” surveillance.