Seoul Orthohantavirus in Wild Black Rats, Senegal, 2012-2013

Prevalence of orthohantavirus in rodents: A systematic review and meta-analysis

INTRODUCTION

Orthohantaviruses are zoonotic diseases transmitted mainly by rodents, particularly mice and rats, associated with multiple outbreaks in different continents. Despite its epidemiological relevance, there is a lack of systematic reviews and meta-analyses.

OBJECTIVE

To determine the combined global prevalence of Orthohantavirus infection in rodents.

METHODS

A systematic literature review was carried out in six databases (Web of Sciences, Scopus, PubMed, SciELO, Lilacs, Google Scholar) to evaluate the proportion of rodents infected with Orthohantavirus, defined by molecular and immunological techniques. The meta-analysis used a random effects model for the pooled prevalence and 95% confidence intervals (95%CI). Heterogeneity measures, Cochrane's Q, the I² index and the tau-squared test were estimated.

RESULTS

A total of 35,706 rodents (229 studies) were evaluated for ELISA, in which 3360 were found positive, for seroprevalence of 4.9% (95%CI 4.3-5.4%) (τ² = 0.001; Q = 4027.708; I² = 94.339%, p < 0.001). For PCR (N = 8812, 91 studies) it was 3.2% (95%CI 2.5-3.9%) (τ² = 0.001; Q = 397.483; I² = 77.358%; p < 0.001). For IFA (N = 555, 7 studies) it was 18.8% (95%CI 9.4-28.2%) (τ² = 0.011; Q = 51.239; I² = 88.29%, p < 0.001). At the genus level, the studies evaluated Oligoryzomys (8.98%), Reithrodontomys (8.98%), Peromyscus (8.20%), Rattus (8.20%), and Akodon (6.64%).

CONCLUSIONS

The global prevalence of Orthohantavirus is worrisome, with an increase in its report in certain regions, including Latin America. In this context, rodents have a role as reservoirs. The data of the present meta-analysis showed considerable seroprevalences with great variations by years, countries and Orthohantavirus species.

Role of Seaports and Imported Rats in Seoul Hantavirus Circulation, Africa

Seoul orthohantavirus (SEOV) is not considered a major public health threat on the continent of Africa. However, Africa is exposed to rodentborne SEOV introduction events through maritime traffic after exponential growth of trade with the rest of the world. Serologic studies have already detected hantavirus antibodies in human populations, and recent investigations have confirmed circulation of hantavirus, including SEOV, in rat populations. Thus, SEOV is a possible emerging zoonotic risk in Africa. Moreover, the range of SEOV could rapidly expand, and transmission to humans could increase because of host switching from the usual brown rat (Rattus norvegicus) species, which is currently invading Africa, to the more widely installed black rat (R. rattus) species. Because of rapid economic development, environmental and climatic changes, and increased international trade, strengthened surveillance is urgently needed to prevent SEOV dissemination among humans in Africa.

Genetic Characterization of Seoul Virus in the Seaport of Cotonou, Benin

Seoul virus is a zoonotic pathogen carried by the brown rat Rattus norvegicus. Information on its circulation in Africa is limited. In this study, the virus was detected in 37.5% of brown rats captured in the Autonomous Port of Cotonou, Benin. Phylogenetic analyses place this virus in Seoul virus lineage 7.

Prevalence of Orthohantavirus-Reactive Antibodies in Humans and Peri-Domestic Rodents in Northern Ethiopia

In 2012, Tigray orthohantavirus was discovered in Ethiopia, but its seasonal infection in small mammals, and whether it poses a risk to humans was unknown. The occurrence of small mammals, rodents and shrews, in human inhabitations in northern Ethiopia is affected by season and presence of stone bunds. We sampled small mammals in two seasons from low- and high-density stone bund fields adjacent to houses and community-protected semi-natural habitats in Atsbi and Hagere Selam, where Tigray orthohantavirus was first discovered. We collected blood samples from both small mammals and residents using filter paper. The presence of orthohantavirus-reactive antibodies in blood was then analyzed using immunofluorescence assay (human samples) and enzyme linked immunosorbent assays (small mammal samples) with Puumala orthohantavirus as antigen. Viral RNA was detected by RT-PCR using small mammal blood samples. Total orthohantavirus prevalence (antibodies or virus RNA) in the small mammals was 3.37%. The positive animals were three Stenocephalemys albipes rats (prevalence in this species = 13.04%). The low prevalence made it impossible to determine whether season and stone bunds were associated with orthohantavirus prevalence in the small mammals. In humans, we report the first detection of orthohantavirus-reactive IgG antibodies in Ethiopia (seroprevalence = 5.26%). S. albipes lives in close proximity to humans, likely increasing the risk of zoonotic transmission.

Multiple Mammarenaviruses Circulating in Angolan Rodents

Rodents are a speciose group of mammals with strong zoonotic potential. Some parts of Africa are still underexplored for the occurrence of rodent-borne pathogens, despite this high potential. Angola is at the convergence of three major biogeographical regions of sub-Saharan Africa, each harbouring a specific rodent community. This rodent-rich area is, therefore, strategic for studying the diversity and evolution of rodent-borne viruses. In this study we examined 290 small mammals, almost all rodents, for the presence of mammarenavirus and hantavirus RNA. While no hantavirus was detected, we found three rodent species positive for distinct mammarenaviruses with a particularly high prevalence in Namaqua rock rats (Micaelamys namaquensis). We characterised four complete virus genomes, which showed typical mammarenavirus organisation. Phylogenetic and genetic distance analyses revealed: (i) the presence of a significantly divergent strain of Luna virus in Angolan representatives of the ubiquitous Natal multimammate mouse (Mastomys natalensis), (ii) a novel Okahandja-related virus associated with the Angolan lineage of Micaelamys namaquensis for which we propose the name Bitu virus (BITV) and (iii) the occurrence of a novel Mobala-like mammarenavirus in the grey-bellied pygmy mouse (Mus triton) for which we propose the name Kwanza virus (KWAV). This high virus diversity in a limited host sample size and in a relatively small geographical area supports the idea that Angola is a hotspot for mammarenavirus diversity.