Nadine N'dilimabaka - Academia.edu (original) (raw)

Papers by Nadine N'dilimabaka

Journal of Zoology, Apr 8, 2023

Rodents (Rodentia) are the most abundant and diverse order of mammals, present in all habitats, i... more Rodents (Rodentia) are the most abundant and diverse order of mammals, present in all habitats, including urban areas. The traffic linked to globalisation has favoured their involvement in biological invasions that have an impact on local biodiversity, the economy and human health. In Franceville, Gabon, little is known about the rodent community. We therefore studied the composition and distribution of rodents along a gradient highlighting the heterogeneity of the city's landscape. The three habitat types studied showed no difference in small mammal abundance, while the diversity index was higher in the vegetated habitat (SDI = 0.73) compared to the outdoor (SDI = 0.71) and indoor (SDI = 0.45) habitats. Our work shows the importance of vegetal remnants in the city for the maintenance of native species. It also highlights the impact of introduced species on small mammal assemblages and the need for management to reduce the factors of their proliferation.

Investment in Africa over the past year with regards to SARS-CoV-2 genotyping has led to a massiv... more Investment in Africa over the past year with regards to SARS-CoV-2 genotyping has led to a massive increase in the number of sequences, exceeding 100,000 genomes generated to track the pandemic on the continent. Our results show an increase in the number of African countries able to sequence within their own borders, coupled with a decrease in sequencing turnaround time. Findings from this genomic surveillance underscores the heterogeneous nature of the pandemic but we observe repeated dissemination of SARS-CoV-2 variants within the continent. Sustained investment for genomic surveillance in Africa is needed as the virus continues to evolve, particularly in the low vaccination landscape. These investments are very crucial for preparedness and response for future pathogen outbreaks.One-Sentence SummaryExpanding Africa SARS-CoV-2 sequencing capacity in a fast evolving pandemic.

Open access journal of biomedical science, Mar 25, 2022

Viruses of the family Arenaviridae are enveloped viruses with a genome consisting of two single-s... more Viruses of the family Arenaviridae are enveloped viruses with a genome consisting of two single-stranded RNA segments, designated small (S) and large (L). The family is divided into three genera: Mammarenavirus which have rodents and bats as natural reservoirs; Hartmanivirus and Reptarenavirus [1] ABSTRACT LCMV RNA has been detected both in its natural host reservoir, the house mouse Mus musculus, and other rodent species in Gabon. In addition, many pathogenic and nonpathogenic Mammarenavirus reservoirs are also present in the country; suggesting that other arenaviruses should be present together with new virus hosts. Considering the importance of rodent-born arenaviruses for human health, we look for the presence of these viruses in rodents, bats and bushmeats collected in the entire Gabonese territory. Here we failed to detect arenaviruses RNA in all the tested samples. This absence can be explained by several hypotheses: (i) the geographical hypothesis, (ii) the genetic structure of the host that can impact viral distribution, (iii) the relationship between host density and the presence of the virus, (iv) the dilution effect, and (v) the detection method used. To get more information about the circulation of arenaviruses and their host reservoirs in Gabon, it is necessary to both enrich collected animals and make additional analyses. The enrichment is related to the increased number and diversity of animal species and the extension of the collection to all periods of the year. Additional analyses should be: (i) the use of complementary specific multiplex systems of PCR targeting both segments of arenaviruses, (ii) serological analyses and Whole Genome Sequencing technologies.

Veterinary World, Jul 13, 2024

Background and Aim: Cryptosporidium spp. members of the phylum Apicomplexa are obligate protozoan... more Background and Aim: Cryptosporidium spp. members of the phylum Apicomplexa are obligate protozoan parasites capable of infecting various vertebrate hosts, including rodents and chickens. Infection caused by these parasites may lead to zoonotic diseases in humans. The aim of this study was to estimate the prevalence of Cryptosporidium spp. in rodents and domestic chickens sampled in Franceville, Gabon.

Materials and Methods: Two hundred and eighty-five samples were collected, of which 185 samples were from rodents and 100 from domestic chickens. Microscopy after modified Ziehl-Neelsen staining and nested polymerase chain reaction targeting the small subunit (SSU) rRNA gene was used to examine Cryptosporidium spp.

Results: The overall prevalence of Cryptosporidium oocysts was 55.8%, with a prevalence of 72.4% in rodents and 25.0% in domestic chickens. Molecular analysis showed that Cryptosporidium spp. were present in 4.0% of the samples. No significant correlation was observed between Cryptosporidium spp. carriage and sex or location in this study. These results indicate that Cryptosporidium spp. persist and circulate in the studied animal species in Franceville, Gabon.

Conclusion: Infection with Cryptosporidium is very common in rodents and chickens in Franceville. The potential risk of human contamination cannot be ruled out. More research should be conducted to characterize Cryptosporidium species circulating in rodents and chickens in Gabon. Such studies are essential to better understand the epidemiology of this protozoan and its potential impact on public health.

Keywords: Cryptosporidium spp., domestic chickens, Gabon, Oocysts, rodents.

Animals

Astroviruses (AstVs), enteroviruses (EVs), and caliciviruses (CaVs) infect several vertebrate tax... more Astroviruses (AstVs), enteroviruses (EVs), and caliciviruses (CaVs) infect several vertebrate taxa. Transmitted through the fecal–oral route, these enteric viruses are highly resistant and can survive in the environment, thereby increasing their zoonotic potential. Here, we screened for AstVs, EVs, and CaVs to investigate the role of domestic animals in the emergence of zoonoses, because they are situated at the human/wildlife interface, particularly in rural forested areas in Central Africa. Rectal swabs were obtained from 123 goats, 41 sheep, and 76 dogs in 10 villages located in northeastern Gabon. Extracted RNA reverse-transcribed into cDNA was used to detect AstVs, EVs, and CaVs by amplification of the RNA-dependent RNA polymerase (RdRp), or capsid protein (VP1) gene using PCR. A total of 23 samples tested positive, including 17 goats for AstVs, 2 goats, 2 sheep, 1 dog for EVs, and 1 dog for CaVs. Phylogenetic analyses revealed that AstV RdRp sequences clustered with sheep-, go...

Frontiers in Cellular and Infection Microbiology

The COVID-19 disease presents a large range of clinical manifestations and includes asymptomatic,... more The COVID-19 disease presents a large range of clinical manifestations and includes asymptomatic, mild, and severe cases. The level of severity is related to parameters associated with immunity, genetics, and biochemistry. Africa shows one of the lowest COVID-19 fatality rates but very few data on the biochemical markers of COVID-19 in patients and the factors associated with disease severity are available for the continent. In Gabon, the COVID-19 fatality rate is only 0.63% but almost no data on biomarkers in COVID-19 patients have been published. Both the number of COVID-19 cases and the mortality rate reported in Africa in general, and in Gabon in particular, are lower than in non-African countries. As such, understanding the factors associated with disease severity in Gabonese patients is a crucial step to better understand the disease in the African context and prepare for future COVID-19 waves and other epidemics of emerging diseases. Here, we compared biochemical and hematolo...

A) Co-cultured endothelial cells (ECs) and parasitized red blood cells (PRBCs) after Ann... more A) Co-cultured endothelial cells (ECs) and parasitized red blood cells (PRBCs) after Annexin V and propidium iodide (PI) staining. B) Human lung endothelial cell (HLEC) apoptosis induced by the different P. falciparum isolates (A, B and C) when the co-cultures are made in the standard culture media (LCm) or in the modified culture medium (MLCm). C) Human brain endothelial cell (HBEC) apoptosis induced by the different P. falciparum isolates (A, B and C) when the co-cultures are made in the standard culture media (BCm) or in the modified culture medium (MBCm). The percentage of apoptotic cells was calculated after microscopy enumeration of Annexin V and propidium iodide positive cells in 1000 ECs. The results are expressed as mean values, and standard deviation are shown for duplicate wells from three biological replicates. Significance at p<0.005 is indicated by **.</p

The number of adherent PRBC per 500 ECs from each isolate to HLEC (A) and HBEC (B), as e... more The number of adherent PRBC per 500 ECs from each isolate to HLEC (A) and HBEC (B), as enumerated after incubation for 1 h and three washed to remove non-adherent cells. Isolates A and C with increased levels of cytoadherence selected for by panning on HLEC and HBEC, (C) and (D) respectively, do not lead to increased apoptosis when co-cultured with HLEC and HBEC, (E) and (F) respectively. Trypsin treatment that abolishes cytoadherence in the isolates does not alter their ability to induce cell death of co-cultured HLEC and HBEC (G) and (H) respectively. In all panels, the results are expressed as means with standard deviations from duplicate wells from three biological replicates. Significance levels are denoted by * for p<0.05, and ** p<0.005.</p

Primers used for reverse-transcriptase polymerase chain reaction (RT-qPCR) experiments.&... more Primers used for reverse-transcriptase polymerase chain reaction (RT-qPCR) experiments.</p

Frontiers in Medicine

Since the onset of the COVID-19 pandemic, the SARS-CoV-2 viral dynamics in Africa have been less ... more Since the onset of the COVID-19 pandemic, the SARS-CoV-2 viral dynamics in Africa have been less documented than on other continents. In Gabon, a Central African country, a total number of 37,511 cases of COVID-19 and 281 deaths have been reported as of December 8, 2021. After the first COVID-19 case was reported on March 12, 2020, in the capital Libreville, the country experienced two successive waves. The first one, occurred in March 2020 to August 2020, and the second one in January 2021 to May 2021. The third wave began in September 2021 and ended in November 2021. In order to reduce the data gap regarding the dynamics of SARS-CoV-2 in Central Africa, we performed a retrospective genotyping study using 1,006 samples collected from COVID-19 patients in Gabon from 2020 to 2021. Using SARS-CoV-2 variant screening by Real-Time Quantitative Reverse Transcription PCR (qRT-PCR) and whole genome sequencing (WGS), we genotyped 809 SARS-CoV-2 samples through qRT-PCR and identified to gene...

Figure 5. Multiple correspondence analysis on infected bats. Projection of the variables (a); pro... more Figure 5. Multiple correspondence analysis on infected bats. Projection of the variables (a); projection of individuals (b).

Figure 4. Comparison of the proportions of infected bats by genus (a), species (b), age (c), sex ... more Figure 4. Comparison of the proportions of infected bats by genus (a), species (b), age (c), sex (d), month (e) and site (f). The error bars represent the confidence interval.

Figure 1. Location of animal sampling sites in Gabon.

Figure 3. Identification of viral sequences from raw data generated by high-throughput sequencing... more Figure 3. Identification of viral sequences from raw data generated by high-throughput sequencing. From the raw data, BLAST was performed against viral sequences from RefSeq to identify potential viruses. Then to discard false positive calls, reads having aligned with viral references were again aligned with NCBI Nucleotide database (nr).

Figure 2. Phylogenetic relationship of coronaviruses based on a fragment of 495-bp of RdRP gene (... more Figure 2. Phylogenetic relationship of coronaviruses based on a fragment of 495-bp of RdRP gene (a). Phylogenetic relationship between Alphacoronavirus (b), Betacoronavirus (c) and bat coronaviruses from this study are highlighted.

American Journal of Tropical Medicine and Hygiene, 2017