Through international trades, Europe, Africa and South America share a long history of exchanges, potentially of pathogens. We used the worldwide parasiteToxoplasma gondiito test the hypothesis of a historical influence on pathogen genetic diversity in Benin, a West African country with a longstanding sea trade history. In Africa,T.gondiispatial structure is still non-uniformly studied and very few articles have reported strain genetic diversity in fauna and clinical forms of human toxoplasmosis so far, even in African diaspora. Sera from 758 domestic animals (mainly poultry) in two coastal areas (Cotonou and Ouidah) and two inland areas (Parakou and Natitingou) were tested forT.gondiiantibodies using a Modified Agglutination Test (MAT). The hearts and brains of 69 seropositive animals were collected for parasite isolation in a mouse bioassay. Forty-five strains were obtained and 39 genotypes could be described via 15-microsatellite genotyping, with a predominance of the autochthonous African lineage Africa 1 (36/39). The remaining genotypes were Africa 4 variant TUB2 (1/39) and two identical isolates (clone) of Type III (2/39). No difference in terms of genotype distribution between inland and coastal sampling sites was found. In particular, contrarily to what has been described in Senegal, no type II (mostly present in Europe) was isolated in poultry from coastal cities. This result seems to refute a possible role of European maritime trade in Benin despite it was one of the most important hubs during the slave trade period. However, the presence of the Africa 1 genotype in Brazil, predominant in Benin, and genetic analyses suggest that the triangular trade was a route for the intercontinental dissemination of genetic strains from Africa to South America. This supports the possibility of contamination in humans and animals with potentially imported virulent strains.

Leptospirosis is a zoonotic disease that is caused by spirochete bacteria of the genus Leptospira. Around the world, one million people each year are infected, leading to 60,000 deaths. Infection occurs through contact with environmental pathogens excreted by mammals (notably rodents). Data on Leptospira and leptospirosis in Africa are rather scarce, especially in urban habitats though these appear to be favourable environments for the pathogen circulation and human contamination. Using qPCR, DNA sequencing as well as MST/VNTR approaches, we examined Leptospira occurrence and genetic diversity in 779 commensal small mammals that were sampled over 2 years in the city centre of Cotonou, Benin, from three neighbourhoods with contrasting socio‐environmental conditions. Overall prevalence reached 9.1%. However, very marked variations in both space and time were observed, with local peaks of high prevalence but no clear seasonal pattern. In most sites that could be regularly sampled, Leptospira‐positive rodents were found at least once, thus confirming the widespread circulation of the pathogen within small mammal communities of Cotonou. Interestingly, an unusual diversity of small mammal‐borne Leptospira species and genotypes was retrieved, with up to four species and three different genovars within the same neighbourhood, and even instances of two species and two genovars identified simultaneously within the same household. To our knowledge, such a high genetic diversity has never been described at such a fine scale, a fortiori in Africa and, more generally, within an urban environment. Altogether, our results underline that much remains unknown about leptospirosis as well as the associated infectious risk in African cities where the disease may be massively over‐looked.

Black rats (Rattus rattus) are native to the Indian subcontinent but have now colonized most continents and islands following human movements and international trade. They are involved in the circulation and transmission to humans of many zoonotic agents as well as in massive damage to food stocks and native biodiversity in the regions they have settled. This study investigates the genetic diversity and possible origins of black rats from Benin, West Africa. We sequenced the complete mitochondrial cytochrome b gene in 90 individuals from nine localities in Benin. These sequences were subsequently compared to 390 other cytochrome b haplotypes from individuals from various European, Asian, American and African localities. Nucleotide polymorphism analysis, haplotype network and maximum likelihood phylogenetic tree reconstructions showed low mitochondrial diversity in black rats from Benin. Our results also suggest at least two distinct introduction events: one introduction probably occurred during the spice trade (15th-17th century) through the Indies Road connecting Europe to Asia. Other introduction events could have occurred more recently following the intensification of globalized trade from the eighteenth century, and onwards.

Leptospirosis is caused by spirochete bacteria of the genus Leptospira that affect one million and kill 60,000 persons annually in the world, who get infected through environmental mammal-excreted (notably rodent) pathogens. Using qPCR and DNA sequencing approaches, we here examine Leptospira occurrence and diversity in 971 commensal small mammals in urban and peri-urban habitats from south Benin, where socio-environmental conditions are favorable for human contamination. Prevalence reached 12.9% on average, but showed very important variations in both space and time, thus pointing toward a role of local processes in the maintenance and circulation of rodent-borne leptospires in the area. Prevalence peaks may occur during or one month after moderate (100–200 mm) monthly rainfall, suggesting that rodent-borne leptospires may be more prevalent when standing waters are present, but not at their highest levels (i.e., floods). However, this pattern will have to be confirmed through proper diachronic analysis. Finally, an incomplete but significant host-specificity was observed, with L. kirschneri retrieved only in African shrews, and the invasive Rattus norvegicus and the native Mastomys natalensis preferentially infected by L. interrogans and L. borgpeterseni, respectively. Our study highlights the urgent need for investigations on human leptospirosis in the extensively urbanized Abidjan–Lagos corridor.

International trade has been favouring the dissemination of a wide suite of invasive alien species. Upstream prevention through the monitoring of entry points is identified as an appropriate strategy to achieve control of bioinvasions and their consequences. Maritime transportation has been responsible for the introduction worldwide of exotic rodents that are major pests for crops and food stocks as well as reservoirs of many zoonotic pathogens. In order to limit further dissemination, the International Health Regulation constrains decisions makers and socio‐economic stakeholders to manage ship‐mediated import/export of rodents within seaports. Unfortunately, eco‐evolutionary insights into rodent introduction events that could guide preventive actions in seaports are very scarce. In order to bridge this gap, we here describe the results of a 3 year‐long survey of small mammals conducted in the Port of Cotonou, Benin. Our aim was to assess the spatiotemporal distribution, diversity and relative abundance of invasive and native rodents. 960 small mammal individuals were captured in nine within‐seaport sites. We found (i) a marked predominance of invasive species (84% of the individuals belonging to Mus musculus, Rattus rattus, R. norvegicus), (ii) with native species (i.e. Mastomys natalensis and the shrew Crocidura olivieri) essentially restricted to peripheral non‐industrial areas, as well as (iii) a fine‐scale spatial segregation stable over time between the invasive Norway rats and house mice on the one hand, and the black rats and shrews on the other hand. Furthermore, trapping before and after two successive rodent control campaigns indicates that they were ineffective and that subsequent rodent recolonisation occurred 6–12 months following intervention. Synthesis and applications. Our results are discussed in terms of ecological processes at play (e.g. interspecific interactions) and operational recommendations (e.g. assessment of proper eradication units, environmental modifications).

Toxoplasmosis, one of the most prevalent parasitic infections in humans and animals, is caused by the intracellular protozoan parasiteToxoplasma gondii. Small mammals play a key role as intermediate reservoir hosts in the maintenance of theT. gondiilife cycle. In this study, we estimated the molecular prevalence and provide genetic diversity data forT. gondiiin 632 small mammals sampled in four areas of Cotonou city, Benin. Both the brain and heart of each individual were screened throughT. gondii-targeting qPCR, and positive samples were then genotyped using a set of 15T. gondii-specific microsatellites. Prevalence data were statistically analyzed in order to assess the relative impact of individual host characteristics, spatial distribution, composition of small mammal community, and urban landscape features. An overallT. gondiimolecular prevalence of 15.2% was found and seven genotypes, all belonging to theAfrica 1lineage, could be retrieved from the invasive black ratRattus rattusand the native African giant shrewCrocidura olivieri. Statistical analyses did not suggest any significant influence of the environmental parameters used in this study. Rather, depending on the local context,T. gondiiprevalence appeared to be associated either with black rat, shrew, or mouse abundance or with the trapping period. Overall, our results highlight the intricate relationships between biotic and abiotic factors involved inT. gondiiepidemiology and suggest thatR. rattusandC. olivieriare two competent reservoirs for theAfrica 1lineage, a widespread lineage in tropical Africa and the predominant lineage in Benin.