Occupational Hantavirus Infections in Agricultural and Forestry Workers: A Systematic Review and Metanalysis

Abstract

Hantaviruses are zoonotic pathogens that can cause serious human disorders, including hemorrhagic fever with renal syndrome and hantavirus cardiopulmonary syndrome. As the main risk factor for human infections is the interaction with rodents, occupational groups such as farmers and forestry workers are reportedly at high risk, but no summary evidence has been collected to date. Therefore, we searched two different databases (PubMed and EMBASE), focusing on studies reporting the prevalence of hantaviruses in farmers and forestry workers. Data were extracted using a standardized assessment form, and results of such analyses were systematically reported, summarized and compared. We identified a total of 42 articles, including a total of 28 estimates on farmers, and 22 on forestry workers, with a total workforce of 15,043 cases (821 positive cases, 5.5%). A pooled seroprevalence of 3.7% (95% confidence interval [95% CI] 2.2-6.2) was identified in farmers, compared to 3.8% (95% CI 2.6-5.7) in forestry workers. Compared to the reference population, an increased occurrence was reported for both occupational groups (odds ratio [OR] 1.875, 95% CI 1.438-2.445 and OR 2.892, 95% CI 2.079-4.023 for farmers and forestry workers, respectively). In summary, our analyses stress the actual occurrence of hantaviruses in selected occupational groups. Improved understanding of appropriate preventive measures, as well as further studies on hantavirus infection rates in reservoir host species (rodents, shrews, and bats) and virus transmission to humans, is needed to prevent future outbreaks.

Keywords: climate change; hantaviruses; public health; sectors of activity; work-related disease; workers; zoonoses.

Figure 1

PRISMA flow chart for retrieved studies.

Figure 2

Forest plot representing the estimated pooled prevalence for seropositive status for hantaviruses among agricultural workers. Pooled prevalence rate was estimated in 3.7% (95% CI 2.2–6.2), with estimates that were considerably greater in studies performed in Asian countries (7.4%, 95% CI 3.0–17.0), followed by African countries (7.1%, 95% CI 3.2–14.8), European (3.0%, 95% CI 1.5–6.2) and American countries (3.0%, 95% CI 0.9–9.2). Notes: OW = Old World (i.e., Eurasia and Africa); NW = New World (North and Central/South America).

Figure 3

Forest plot representing the association of positive status for hantavirus serology (i.e., “Event”) in Agricultural Workers (AW) compared to the reference population (Non AW). In summary, seropositivity for Hantavirus was associated with the occupational status as AW with an odds ratio (OR) equal to 1.875, 95% confidence interval (95% CI) 1.438–2.445.

Figure 4

Forest plot representing the estimated pooled prevalence for seropositive status for hantaviruses among forestry workers. Pooled prevalence rate was estimated in 3.8% (95% CI 2.6–5.7), with estimates that were considerably greater in studies performed in European countries (4.1%, 95% CI 2.7–6.1), compared to North and South American countries (1.6%, 95% CI 0.2–13.1). Notes: OW = Old World (i.e., Eurasia and Africa); NW = New World (North and Central/South America).

Figure 5

Forest plot representing the association of positive status for hantavirus serology (i.e., “Event”) in forestry workers (FW) compared to the reference population (non FW). In summary, seropositivity for hantavirus was associated with the occupational status as AW with an odds ratio (OR) equal to 2.892, 95% confidence interval (95% CI) 2.079–4.023.

Figure 6

Forest plot comparing the positive status for hantavirus serology (i.e., “Event”) in forestry workers (FW) and agricultural workers (AW) in studies that reported on both occupational groups. In summary, working as FW was associated with seropositive status with an odds ratio (OR) equal to 1.857, 95% confidence interval (95% CI) 0.908–3.798.

Figure 7

Border-enhanced funnel plots for studies included in the meta-analysis for agricultural workers (a) and forestry workers (b). Visual inspection of contour-enhanced funnel plots suggested substantial evidence of publication bias for both subgroups, but this was substantially rejected by Egger test for forest workers (i.e., t = −1.81, df = 20, p-value = 0.0857) and confirmed for agricultural workers (t = −3.92, df = 26, p-value = 0.0006 for forestry workers). On the other hand, in radial plots, the studies on agricultural workers (c) and forestry workers (d) were substantially scattered across the regression line, suggesting no significant small study effect.