Urban market gardening and rodent-borne pathogenic Leptospira in arid zones: a case study in Niamey, Niger

Leptospirosis essentially affects human following contact with rodent urine-contaminated water. As such, it was mainly found associated with rice culture, recreational activities and flooding. This is also the reason why it has mainly been investigated in temperate as well as warm and humid regions, while arid zones have been only very occasionally monitored for this disease. In particular, data for West African countries are extremely scarce. Here, we took advantage of an extensive survey of urban rodents in Niamey, Niger, in order to look for rodent-borne pathogenic[i] Leptospira[/i] species presence and distribution across the city. To do so, we used high throughput bacterial 16S-based metabarcoding, [i]lipL32[/i] gene-targeting RT-PCR, rrs gene sequencing and VNTR typing as well as GIS-based multivariate spatial analysis. Our results show that leptospires seem absent from the core city where usual [i]Leptospira[/i] reservoir rodent species (namely [i]R. rattus[/i] and [i]M. natalensis[/i]) are yet abundant. On the contrary, [i]L. kirschneri[/i] was detected in [i]Arvicanthis niloticus[/i] and [i]Cricetomys gambianus[/i], two rodent species that are restricted to irrigated cultures within the city. Moreover, the VNTR profiles showed that rodent-borne leptospires in Niamey belong to previously undescribed serovars. Altogether, our study points towards the importance of market gardening in maintain and circulation of leptospirosis within Sahelian cities. In Africa, irrigated urban agriculture constitutes a pivotal source of food supply, especially in the context of the ongoing extensive urbanization of the continent. With this in mind, we speculate that leptospirosis may represent a zoonotic disease of concern also in arid regions that would deserve to be more rigorously surveyed, especially in urban agricultural settings

Tuberculosis in Vaccinated versus Unvaccinated Children with BCG Vaccine in Niamey: Epidemiological, Diagnostic and Outcome Aspects

Introduction: Tuberculosis remains a public health problem worldwide. The BCG vaccination is one of response means. The objective of this work was to study impact of BCG vaccination on morbidity and mortality related to childhood tuberculosis in Niamey. Patients and methods: It was a multicenter prospective and comparative study from January to September 2017 in two-referral hospital centers of Niamey and the National Anti-Tuberculosis Center. The study population consisted exhaustively of children aged 0 to 15 years old suffering from tuberculosis. Epidemiological, diagnostic and evolving aspects in vaccinated and unvaccinated children were studied. Statistical tests used were Pearson's Chi² and Fisher's exact test (p <0.05). Results: Ninety-one children were studied. The BCG vaccination rate was 60.4%. The mean age of children was 6 years 11 months [3 months-15 years]. Children under 2 years of age were less affected (11%) in vaccinated children than in unvaccinated children (3.2%). No association was found between duration of tuberculosis signs (p = 0.37), expression of tuberculin skin test (p = 0.43), and the children's BCG vaccination status. On the other hand, there was a significant link between vaccination status and the results of microscopic examination of sputum or gastric fluid (p = 0.02), occurrence of complications (p = 0.014) and death risk (p = 0.003). Conclusion: This study shows that children’s BCG vaccination status interferes with some aspects of tuberculosis. Therefore, fighting against tuberculosis must be intensified, through combination of many strategies including vaccination

Tuberculosis in Vaccinated versus Unvaccinated Children with BCG Vaccine in Niamey: Epidemiological, Diagnostic and Outcome Aspects

Introduction: Tuberculosis remains a public health problem worldwide. The BCG vaccination is one of the response means. The objective of this work was to study the impact of BCG vaccination on morbidity and mortality related to childhood tuberculosis in Niamey. Patients and methods: It was a multicenter prospective and comparative study from January to September 2017 in two-referral hospital centers of Niamey and the National Anti-Tuberculosis Center. The study population consisted exclusively of children aged 0 to 15 years old suffering from tuberculosis. Epidemiological, diagnostic, and evolving aspects in vaccinated and unvaccinated children were studied. Statistical tests used were Pearson's Chi² and Fisher's exact test (p <0.05). Results: Ninety-one children were studied. The BCG vaccination rate was 60.4%. The mean age of children was 6 years 11 months [3 months-15 years]. Children under 2 years of age were less affected (11%) in vaccinated children than in unvaccinated children (3.2%). No association was found between the duration of tuberculosis signs (p = 0.37), expression of tuberculin skin test (p = 0.43), and the children's BCG vaccination status. On the other hand, there was a significant link between vaccination status and the occurrence of complications (p = 0.014), and death risk (p = 0.003). Conclusion: This study shows that children’s BCG vaccination status correlates with some aspects of tuberculosis. Unvaccinated children have a significantly higher risk of complications and death from TB

Tuberculosis in Vaccinated versus Unvaccinated Children with BCG Vaccine in Niamey: Epidemiological, Diagnostic and Outcome Aspects

Introduction: Tuberculosis remains a public health problem worldwide. The BCG vaccination is one of response means. The objective of this work was to study impact of BCG vaccination on morbidity and mortality related to childhood tuberculosis in Niamey. Patients and methods: It was a multicenter prospective and comparative study from January to September 2017 in two-referral hospital centers of Niamey and the National Anti-Tuberculosis Center. The study population consisted exhaustively of children aged 0 to 15 years old suffering from tuberculosis. Epidemiological, diagnostic and evolving aspects in vaccinated and unvaccinated children were studied. Statistical tests used were Pearson's Chi² and Fisher's exact test (p <0.05). Results: Ninety-one children were studied. The BCG vaccination rate was 60.4%. The mean age of children was 6 years 11 months [3 months-15 years]. Children under 2 years of age were less affected (11%) in vaccinated children than in unvaccinated children (3.2%). No association was found between duration of tuberculosis signs (p = 0.37), expression of tuberculin skin test (p = 0.43), and the children's BCG vaccination status. On the other hand, there was a significant link between vaccination status and the results of microscopic examination of sputum or gastric fluid (p = 0.02), occurrence of complications (p = 0.014) and death risk (p = 0.003). Conclusion: This study shows that children’s BCG vaccination status interferes with some aspects of tuberculosis. Therefore, fighting against tuberculosis must be intensified, through combination of many strategies including vaccination

Reproduction in urban commensal rodents: the case of Mastomys natalensis from Niamey, Niger

International audienceMost wild Sahelian rodents display a seasonal reproduction that is usually related to rainfall, hence resources availability. Mastomys natalensis is a well-documented and major pest rodent species. In East Africa where it occurs outdoors, the species is characterized by marked population cycles. In contrast, it is mostly associated with humans in West Africa, and appears to live strictly indoors in the Sahel. Here, we have monitored the proportions of M. natalensis juveniles and sexually active adults within the city of Niamey, Niger. Our survey clearly shows that M. natalensis reproduces all year long, with no detectable seasonality. Altogether, our data confirm that reproduction may shift from seasonal to continuous when conditions are more favorable. They also suggest that the urban environment may represent an extreme habitat where resources are permanently available. From the perspective of rodent control in Niamey, our results highlight the need for a constant management policy that should be performed by public authorities

First report of three predatory bugs (Heteroptera: Miridae) in tomato fields infested by the invasive South American tomato pinworm, Tuta absoluta in Niger: an opportunity for biological control?

International audienceAn increase in international trades in goods and services and the movement of humans in recent decades has led to a concomitant increase in the number of exotic insects invading new areas, with some establishing as harmful agricultural pests. That is how the South American tomato pinworm, Tuta absoluta (Lepidoptera: Gelechiidae) has recently and rapidly invaded Niger except the Diffa region. This new pest represents a real threat for tomato production in the country. To this end, the first step includes identifying the fortuitous natural enemies present. For this purpose in Niger, five tomato-infested fields from three distant and climatically different agricultural regions were sampled, with a particular focus on predatory mirids. Based on morphological characters and molecular barcoding approach, Nesidiocoris tenuis, N. volucer and N. callani (Miridae: Dyciphini) were reported for the first time in Niger and associated with tomato pests providing new insights upon their distribution areas and ecology, and genetic diversity. These findings are discussed in the framework of T. absoluta management and also the need of accurately identifying the community of natural enemies when facing invasive species

A new suite of twenty-two polymorphic microsatellite loci in the parasitic wasp, Habrobracon hebetor (Hymenoptera: Braconidae): Promising molecular tools for studying the population genetics of several beneficial braconid species

Combining a biotin-enrichment protocol and 454GS-FLX titanium pyrosequencing technology, we characterised 22 polymorphic microsatellite loci from the parasitic wasp, Habrobracon hebetor (Say) (Hymenoptera: Braconidae), a cosmopolitan species commonly used in biological control against a wide range of both major lepidopterous pests of stored products and field crops in different parts of the world. Three multiplex PCR sets were optimised and characterised across 46 H. hebetor specimens from two samples collected from millet fields in Niger. Two to 11 alleles were found per locus and observed heterozygosity ranged from 0.289 to 0.826. Polymorphism was detected in both samples with a similar level of observed heterozygosity (0.482 vs. 0.502) and number of alleles (4.1 vs. 3.6). Deviation from Hardy-Weinberg equilibrium was detected at the same five loci in both samples and five or seven more loci in each sample but was not associated with heterozygote deficiencies. Even though evidence for linkage disequilibrium was found between a few alleles, these new loci segregated independently. The variability of the 22 loci will enable estimates of genetic diversity and structure patterns, as well as gene flow between H. hebetor populations at different spatial scales. Cross-species amplifications were successful among the six Bracon spp. tested and nine loci will be particularly appropriate for population genetic studies in B. brevicornis

Pterygodermatites (Mesopectines) niameyensis n. sp. (Nematoda: Rictulariidae), a parasite of Mastomys natalensis (Smith, 1834) (Rodentia: Muridae) from Niger.

International audiencePterygodermatites (Mesopectines) niameyensis n. sp. is described from Mastomys natalensis in Niamey/Niger (West Africa). It differs from other species of same subgenus by the morphology of the head, which presents 4 simple cephalic papillae and nearly axial oral opening, a number of caudal papillae, precloacal cuticular formations, and the spicule length/body length ratio. Scanning electron microscopy shows the presence of 2 pairs of lateral sensory structures for male worms

Strain composition and genetic diversity of the fall armyworm Spodoptera frugiperda (Lepidoptera, Noctuidae): new insights from seven countries in West Africa

International audienceThe fall armyworm (FAW), Spodoptera frugiperda, a major agricultural insect pest in the Western Hemisphere, currently also poses a significant threat to many cereal crops in Africa. FAW consists of two morphocryptic strains, the corn- and the rice strains, which were thought to display typical genetic, physiological and behavioural features. However, this is not absolutely true, rendering direct identification and distribution of the strains impossible in field. Thus, to investigate 1) the composition and diversity of FAW strains, 2) their distribution at various spatial scales, and 3) the host plants they use, in invaded countries we used the COI barcode fragment, a marker capable of accurately distinguishing the two strains. A total of 125 specimens mainly sampled on maize in Niger and Senegal and to a lesser extent in Guinea, Mali, Togo, Burkina Faso and Cape Verde were analyzed. Sixteen haplotypes were identified among which two occurred very frequently. Phylogenetic analysis delineated two lineages, the rice and corn strains, but no typical geographical and host-plant patterns were found. The FAW-strain haplotypes derived from West African specimens were genetically comparable with those sampled elsewhere in Africa, the Americas and Asia. Considering all sites and plants sampled, the corn strain slightly predominated but on maize, the two strains were statistically comparable. Their distribution is largely sympatric at region, field and even maize plant scales. These findings are compared to populations recorded elsewhere and are discussed in the framework of biological invasions, and the management and ecology of the species