Background: Artesunate-amodiaquine (AS-AQ) and artemether-lumefantrine (AL) are first- and second-line treatments for uncomplicated Plasmodium falciparum malaria in Gabon. AL remains highly efficacious, but its widespread use has led to molecular selection of the NFD haplotype on Pfmdr1 and K76 in Pfcrt. In this study, plasmodial infection characteristics and the distribution of the Pfmdr1 and Pfcrt genotypes involved in reduced efficacy of artemisinin-based combination therapy (ACT) were investigated in four Gabonese localities. Methods: A cross-sectional study was conducted in the paediatric units of rural (Lastourville and Fougamou), semi-urban (Koula-Moutou) and urban (Franceville) areas. Malaria was diagnosed with the rapid diagnostic test Optimal-IT^® and confirmed by blood smear. Pfmdr1 codons 86, 184 and 1246 and Pfcrt codon 76 were genotyped by PCR–RFLP and sequencing. Results: Among 1129 included children, the prevalence of plasmodial infection was 79.5 % at Lastourville, 53.6 % at Fougamou, 36.1 % at Koula-Moutou, and 21.2 % at Franceville. The prevalence was significantly higher among children over 60 months of age in both semi-urban (p = 0.01) and urban (p = 0.004) areas. The prevalence of Pfmdr1 wild-type N86 differed significantly between Lastourville (57.8 %) and Koula-Moutou (45.4 %) (p = 0.039). No difference in 184F-carrying parasites was found between Lastourville (73.8 %), Fougamou (81.6 %), Koula-Moutou (83.2 %), and Franceville (80.6 %) (p = 0.240). The prevalence of wild-type D1246 was significantly different between Lastourville (94.1 %), Koula-Moutou (85.6 %) and Franceville (87.3 %) (p = 0.01). The frequency of wild-type K76 was not significantly different across the four sites: Lastourville (16.5 %), Fougamou (27.8 %), Koula-Moutou (17.4 %), and Franceville (29.4 %) (p = 0.09). The mixed genotypes were only found in Lastourville and Franceville. The NFD, YFD and NYD haplotypes were mainly Lastourville (46.6, 25.8, 14.0 %), Fougamou (45.5, 9.1, 42.4 %), Koula-Moutou (35, 6.7, 40.4 %), and Franceville (40.0, 16.0, 32.0 %). Conclusion: This study shows an increase in the prevalence of childhood plasmodial infection in Gabon according to the low socio-economic level, and a high frequency of markers associated with AL treatment failure. Close monitoring of ACT use is needed.

Background: Pediculus humanus, which includes two ecotypes (body and head lice), is an obligate bloodsucking parasite that co-evolved with their human hosts over thousands of years, thus providing a valuable source of information to reconstruct the human migration. Pediculosis due to head lice occurred each year throughout the world and several pathogenic bacteria, which are usually associated with body lice, are increasingly detected in them. In Gabon, where this pediculosis is still widespread, there is a lack of data on genetic diversity of head lice and their associated bacteria. Methods: This study aimed to investigate the phylogeny of head lice collected in Gabon and their associated bacteria, using molecular tools. Between 26 March and 11 April 2018, 691 head lice were collected from 86 women in Franceville. We studied the genetic diversity of these lice based on the cytochrome b gene, then we screened them for DNA of Bartonella quintana, Borrelia spp., Acinetobacter spp., Yersinia pestis, Rickettsia spp., R. prowazekii, Anaplasma spp. and C. burnetii, using real time or standard PCR and sequencing. Results: Overall 74.6% of studied lice belonged to Clade A, 25.3% to Clade C and 0.1% to Clade E. The phylogenetic analysis of 344 head lice yielded 45 variable positions defining 13 different haplotypes from which 8 were novel. Bacterial screening revealed the presence of Borrelia spp. DNA in 3 (0.4%) of 691 head lice belonging to Clade A and infesting one individual. This Borrelia is close to B. theileri (GenBank: MN621894). Acinetobacter spp. DNA has been detected in 39 (25%) of the 156 screened lice; of these 13 (8.3%) corresponded to A. baumannii. Acinetobacter nosocomialis (n = 2) and A. pittii (n = 1) were also recorded. Conclusions: To of our knowledge, this study is the first to investigate the genetic diversity of head lice from Gabon. It appears that Clade C is the second most important clade in Gabon, after Clade A which is known to have a global distribution. The detection of Borrelia spp. DNA in these lice highlight the potential circulation of these bacteria in Gabon.

Background: Malaria is the most deadly parasitic disease and continues to claim more than a half million of deaths across the world each year, mainly those of under-fives children in sub-Saharan Africa. The aim of this study was to determine the epidemiological, clinical and laboratory features of patients with severe malaria at the Centre Hospitalier Régional Amissa Bongo (CHRAB), a referral hospital in Franceville.Methods: It was an observational descriptive study conducted at CHRAB over 10 months. All admitted patients at the emergency ward of all ages presenting with positive test to falciparum malaria diagnosed by microscopy and rapid test with clinical signs of severe illness describe by World Health Organization were enrolled.Results: During this study, 1065 patients were tested positive for malaria, of them 220 had severe malaria. Three quarters (75.0%) were less than 5 years of age. The mean time to consultation was 3.5 ± 1 days. The most frequent signs of severity on admission were dominated by neurological disorders 92.27% (prostration 58.6% and convulsion 24.1%), followed by severe anemia 72.7%, hyperlactatemia 54.6%, jaundice 25% and respiratory distress 21.82%.The other forms such as hypoglycemia, haemoglobinuria, renal failure were found in low proportions < 10%. Twenty-one patients died, coma (aOR = 15.54, CI 5.43–44.41, p < 0.01), hypoglycemia (aOR = 15.37, CI 2.17–65.3, p < 0.01), respiratory distress (aOR = 3.85, CI 1.53–9.73, p = 0.004) and abnormal bleeding (aOR = 16.42, CI 3.57–104.73, p = 0.003) were identified as independent predictors of a fatal outcome. Anemia was associated with decreased mortality.Conclusion: Severe malaria remains a public health problem affecting mostly children under 5 years. Classification of malaria helps identify the most severely ill patients and aids early and appropriate management of the severe malaria cases.

Measles is one of the most infectious diseases with a high mortality rate worldwide. It is caused by the measles virus (MeV) which is a single stranded RNA virus with genetic diversity based on the nucleoprotein gene, including 24 genotypes. In Gabon, several outbreaks occurred in the past few years, especially in 2016 in Libreville and Oyem. A surveillance network of infectious diseases highlighted a measles outbreak which occurred in the south of Gabon from April to June 2017. Clinical specimens of urine, blood, throat and nasal swabs were collected in the two main cities of the Haut-Ogooue province, Franceville and Moanda. Virological investigations based on real-time polymerase chain reaction for molecular diagnosis and conventional PCR for genotype identification were done. Specimens were collected from 139 suspected measles patients. A total of 46 (33.1%) children and adults were laboratory-confirmed cases among which 16 (34.8%) were unvaccinated, 16 (34.8%) had received one dose, and 11 (23.9%) had received two doses of the measles vaccine. Phylogenetic analysis revealed that all the sequences of the nucleoprotein gene belonged to genotype B3. Measles infection was more commonly confirmed among those with one recorded dose compared to suspect cases with none, unknown or two recorded doses. The molecular characterization of the strains showed the circulation of the B3 genotype which is endemic on the African continent, thirty years after the B2 genotype was described in an outbreak in Libreville, the capital of Gabon. These findings highlight that surveillance and molecular investigation of measles should be continued in Gabon.

Background: Urogenital schistosomiasis is endemic in Gabon. Our study aimed to detect the prevalence of urinary schistosomiasis and to evaluate the diagnostic performance of the qPCR technique compared to microscopy for the detection of Schistosoma haematobium at the community level in a semi-rural area. Method: A cross-sectional survey was carried out. Urine samples were examined using Urine TICK test strips, a filtration technique, and qPCR. Schistosoma haematobium was detected by targeting the Dra1 gene. Results: The prevalence of urogenital schistosomiasis was determined and the performance of real-time PCR and urine strips was compared with that of urinary filtration. A total of 281 participants were enrolled in the study. The prevalence of urogenital schistosomiasis was increased slightly with the molecular technique (40.9%) compared to microscopy (36.7%), and the hematuria rate with Urine STICK was 33.5%. SAC (5–14 years old), Pre-SAC (>5 years old), and adolescents (15–17 years old) were the most affected group according to, respectively, whatever method was used. qPCR showed good agreement with microscopy, as well as excellent sensitivity (99.03%) and specificity (93.3). There was a good correlation between the number of eggs per 10 mL and the cycle threshold range. Conclusion: These results show the importance of using a combination of diagnostic tools in the surveillance of schistosomiasis, particularly in preschool children, adolescents, women of childbearing age, and chronic and asymptomatic cases.

The analysis of immune responses in diverse malaria endemic regions provides more information to understand the host’s immune response to Plasmodium falciparum. Several plasmodial antigens have been reported as targets of human immunity. PfAMA1 is one of most studied vaccine candidates; PfRH5 and Pf113 are new promising vaccine candidates. The aim of this study was to evaluate humoral response against these three antigens among children of Lastourville (rural area) and Franceville (urban area). Malaria was diagnosed using rapid diagnosis tests. Plasma samples were tested against these antigens by enzyme-linked immunosorbent assay (ELISA). We found that malaria prevalence was five times higher in the rural area than in the urban area (p < 0.0001). The anti-PfAMA1 and PfRh5 response levels were significantly higher in Lastourville than in Franceville (p < 0.0001; p = 0.005). The anti-AMA1 response was higher than the anti-Pf113 response, which in turn was higher than the anti-PfRh5 response in both sites. Anti-PfAMA1 levels were significantly higher in infected children than those in uninfected children (p = 0.001) in Franceville. Anti-Pf113 and anti-PfRh5 antibody levels were lowest in children presenting severe malarial anemia. These three antigens are targets of immunity in Gabon. Further studies on the role of Pf113 in antimalarial protection against severe anemia are needed.