Non-communicable disease co-morbidity and associated factors in tuberculosis patients: A cross-sectional study in Gabon.

BACKGROUND: There are only limited data from resource-limited settings available on the prevalence of non-communicable diseases and associated risk factors of tuberculosis patients. This study investigated non-communicable disease co-morbidity in tuberculosis patients from Moyen Ogooué Province, Gabon. METHODS: All patients aged 18 years or older consulting for tuberculosis (TB) symptoms in Gabon's Moyen Ogooué province and neighbouring provinces from November 2018 to November 2020 were screened for diabetes mellitus, hypertension, and risk factors thereof (obesity, dyslipidaemia, smoking and alcohol consumption). Logistic regression was performed to identify factors associated with TB-diabetes and TB-hypertension co-morbidities. FINDINGS: Of 583 patients included, 227 (39%) were diagnosed with tuberculosis. In tuberculosis-confirmed patients, the prevalences of hypertension and diabetes were 16·3% and 12·8%, respectively. The prevalence of diabetes was twice as high in tuberculosis patients compared to non-tuberculosis patients. Factors independently associated with hypertension-tuberculosis co-morbidity were age >55 years (aOR=8·5, 95% CI 2·43, 32·6), age 45-54 years (aOR=4.9, 95%CI 1.3-19.8), and moderate alcohol consumption (aOR=2·4; 95% CI 1·02- 5·9), respectively. For diabetes-tuberculosis co-morbidity, age >55 years was positively (aOR=9·13; 95% CI 2·4-39·15), and moderate alcohol consumption inversely associated (aOR=0·26, 95% CI 0·08- 0·73). One-hundred-and-four (46%) of the tuberculosis patients had at least either dyslipidaemia, hypertension, diabetes, or obesity with a majority of newly-diagnosed hypertension and diabetes. INTERPRETATION: Integration of screening of non-communicable diseases and their risk factors during TB assessment for early diagnosis, treatment initiation and chronic care management for better health outcomes should be implemented in all tuberculosis healthcare facilities. FUNDING: This study was supported by WHO AFRO/TDR/EDCTP (2019/893,805) and Deutsches Zentrum für Infektiologie (DZIF/ TTU 02.812).

Focused Assessment with Sonography for Urinary Schistosomiasis (FASUS)-pilot evaluation of a simple point-of-care ultrasound protocol and short training program for detecting urinary tract morbidity in highly endemic settings.

BACKGROUND: Urogenital schistosomiasis (UGS) causes inflammation and fibrosis of the urinary tract. In resource-limited settings, affordable tools for morbidity assessment in clinical care are needed. Point-of-care ultrasound has not yet been validated for UGS-related pathology. METHODS: We developed a protocol for Focused Assessment with Sonography for Urinary Schistosomiasis (FASUS), assessing pathology of the bladder wall, ureters and kidneys. Following standardized training, two clinicians performed FASUS on children and adults with hematuria in Lambaréné, Gabon. Recorded ultrasound clips were remotely reviewed by two ultrasound experts as a diagnostic reference. RESULTS: In 2015 and 2016, scans were performed in 118 patients. The image quality was sufficient in 90% of bladder views and more than 97% of kidney views. UGS-compatible pathology was detected in 51/118 (43%) by the operator and in 46/107 (43%) by the experts among baseline scans of sufficient quality. Inter-rater agreement between operators and experts was very good (κ > 0.8) for hydronephrosis and good (κ > 0.6) for bladder wall thickening. CONCLUSIONS: FASUS is a promising clinical, point-of-care tool for detecting UGS-related urinary tract morbidity in symptomatic patients. Based on larger validation studies, appropriate diagnostic and therapeutic algorithms for the use of FASUS should be established.

Haemostatic changes in urogenital schistosomiasis haematobium: a case-control study in Gabonese schoolchildren.

In many tropical areas schistosomiasis is a major health problem causing hepatosplenic, intestinal or urogenital complaints. Hepatosplenic schistosomiasis mansoni is also characterized by blood coagulation abnormalities. Liver pathology plays a role in the development of haemostatic changes and the parasitic infection may directly affect coagulation. However, these contributing factors cannot be studied separately in hepatosplenic schistosomiasis infections. This pilot study provides insight in haemostatic changes in urinary schistosomiasis by studying coagulation parameters in schistosomiasis haematobium-infected Gabonese schoolchildren. Selection on urinary schistosomiasis patients without hepatosplenic complaints allows for the investigation of the direct effects of the parasite on haemostasis. Levels of von Willebrand Factor (VWF) antigen, active VWF and osteoprotegerin were elevated, indicating inflammation-mediated endothelial activation. In contrast to hepatosplenic schistosomiasis, thrombin-antithrombin complex and D-dimer levels were not affected. Despite its small sample size, this study clearly indicates that Schistosoma haematobium directly alters the activation status of the endothelium, without initiation of coagulation.

Implementation of multidrug-resistant tuberculosis (MDR-TB) treatment in Gabon: lessons learnt from the field.

PURPOSE: Since May 2016, WHO recommended a 9-12 month short-treatment regimen for multidrug-resistant tuberculosis (MDR-TB) treatment known as the 'Bangladesh Regimen'. However, limited data exist on the appropriateness thereof, and its implementation in low- and middle-income countries (LMIC). We report here on the pilot phase of the evaluation of the Bangladesh regimen in Gabon, prior to its endorsement by the WHO. METHODS: This ongoing observational study started in September 2015. Intensive training of hospital health workers as well as community information and education were conducted. GeneXpert-confirmed MDR-TB patients received the second-line anti-tuberculosis drugs (4KmMfxPtoHCfzEZ/5MfxCfzEZ). Sputum smears and cultures were done monthly. Adverse events were monitored daily. RESULTS: Eleven patients have been treated for MDR-TB piloting the short regimen. All were HIV-negative and presented in poor health with extensive pulmonary lesions. The overall sputum culture conversion rate was 64% after 4 months of treatment. Three patients developed marked hearing loss; one a transient cutaneous rash. Of 11 patients in our continuous care, 7 (63.6%) significantly improved clinically and bacteriologically. One (9.1%) patient experienced a treatment failure, two (18.2%) died, and one (9.1%) was lost to follow up. CONCLUSIONS: Our pioneering data on systematic MDR-TB treatment in Gabon, with currently almost total absence of resistance against the second-line drugs, demonstrate that a 9-month regimen has the capacity to facilitate early culture negativity and sustained clinical improvement. Close adverse events monitoring and continuous care are vital to success.

Neutrophil alterations in pregnancy-associated malaria and induction of neutrophil chemotaxis by Plasmodium falciparum.

Pregnancy-associated malaria (PAM) is a severe form of the disease caused by sequestration of Plasmodium falciparum-infected red blood cells (iRBCs) in the developing placenta. Pathogenesis of PAM is partially based on immunopathology, with frequent monocyte infiltration into the placenta. Neutrophils are abundant blood cells that are essential for immune defence but may also cause inflammatory pathology. Their role in PAM remains unclear. We analysed neutrophil alterations in the context of PAM to better understand their contribution to disease development. Pregnant women exposed to Plasmodium falciparum had decreased numbers of circulating neutrophils. Placental-like BeWo cells stimulated with malaria parasites produced the neutrophil chemoattractant IL-8 and recruited neutrophils in a trans-well assay. Finally, immunostaining of a PAM placenta confirmed neutrophil accumulation in the intervillous space. Our data indicate neutrophils may play a role in placental malaria and should be more closely examined as an etiological agent in the pathophysiology of disease.

Demography, maternal health and the epidemiology of malaria and other major infectious diseases in the rural department Tsamba-Magotsi, Ngounie Province, in central African Gabon.

BACKGROUND: Sub-Saharan Africa is undergoing an epidemiological transition from a predominance of infectious diseases to non-communicable and lifestyle related conditions. However, the pace of this transition and the pattern of disease epidemiology are uneven between affluent urban and rural poor populations. To address this question for a remote rural region located in the central African rainforest region of Gabon, this study was conducted to assess reasons for health care attendance and to characterize the epidemiology of malaria and other major infectious diseases for the department of Tsamba Magotsi. METHODS: Major causes for health care attendance were collected from local hospital records. Cross sectional population based surveys were performed for the assessment of local malaria epidemiology. Pregnant women attending antenatal care services were surveyed as a sentinel population for the characterization of chronic viral and parasitic infections in the community. RESULTS: Infectious diseases were responsible for 71% (7469) of a total of 10,580 consultations at the formal health care sector in 2010. Overall, malaria - defined by clinical syndrome - remained the most frequent cause for health care attendance. A cross sectional malaria survey in 840 asymptomatic individuals residing in Tsamba Magotsi resulted in a Plasmodium spp. infection prevalence of 37%. The infection rate in 2-10 year old asymptomatic children - a standard measure for malaria endemicity - was 46% (100 of 217) with P. falciparum as predominant species (79%). Infection with other plasmodial species (P. ovale and P. malariae) presented most commonly as coinfections (23.2%). Prevalence of HIV, HBV, and syphilis were 6.2, 7.3, and 2.5%, respectively, in cross-sectional assessments of antenatal care visits of pregnant women. Urogenital schistosomiasis and the filarial pathogens Loa loa and Mansonella perstans are highly prevalent chronic parasitic infections affecting the local population. CONCLUSIONS: Despite major improvements in the accessibility of Tsamba Magotsi over the past decade the epidemiological transition does not appear to have majorly changed on the spectrum of diseases in this rural Gabonese population. The high prevalence of Plasmodium infection indicates a high burden of malaria related morbidity. Infectious diseases remain one of the most important health issues and further research activities in the field of tropical medicine and infectious diseases could help improve health care for the local population.

Prevalence and risk factor assessment of Tropheryma whipplei in a rural community in Gabon: a community-based cross-sectional study.

Tropheryma whipplei is the causative agent of Whipple's disease and has been detected in stools of asymptomatic carriers. Colonization has been associated with precarious hygienic conditions. There is a lack of knowledge about the epidemiology and transmission characteristics on a population level, so the aim of this study was to determine the overall and age-specific prevalence of T. whipplei and to identify risk factors for colonization. This molecular epidemiological survey was designed as a cross-sectional study in a rural community in Central African Gabon and inhabitants of the entire community were invited to participate. Overall prevalence assessed by real-time PCR and sequencing was 19.6% (95% CI 16-23.2%, n=91) in 465 stool samples provided by the study participants. Younger age groups showed a significantly higher prevalence of T. whipplei colonization ranging from 40.0% (95% CI 27.8-52.2) among the 0-4 year olds to 36.4% (95% CI 26.1-46.6) among children aged 5-10 years. Prevalence decreased in older age groups (p<0.001) from 12.6% (95% CI 5.8-19.4%; 11-20 years) to 9.7% (95% CI 5.7-13.6) among those older than 20. Risk factor analysis revealed young age, male sex, and number of people sharing a bed as factors associated with an increased risk for T. whipplei carriage. These results demonstrate that T. whipplei carriage is highly prevalent in this part of Africa. The high prevalence in early life and the analysis of risk factors suggest that transmission may peak during childhood facilitated through close person-to-person contacts.

Carriage of encapsulated bacteria in Gabonese children with sickle cell anaemia.

Sickle cell anaemia (SCA) is a haemoglobin disorder that alters the deformability of erythrocytes through abnormal polymerization of haemoglobin. Children with SCA have an increased risk of infections with encapsulated bacteria. To guide the antibiotic prophylaxis and vaccinations in children with SCA in Gabon, we characterized Streptococcus pneumoniae, Staphylococcus aureus and Haemophilus influenzae from children with and without SCA. We performed a cross-sectional study and compared nasal and pharyngeal S. pneumoniae, Staph. aureus and H. influenzae isolates from SCA children (n = 73) with comparators matched for age, residence and sex (n = 143) in a matched-comparison analysis. The resistance pattern and capsular type were identified for each isolate. The total carriage rate for S. pneumoniae, Staph. aureus and H. influenzae was 13.8%, 46.7% and 12.5%, respectively, and did not differ between groups (p >0.05). The mean number of days under antibiotic treatment in the past year was higher in children with SCA than in controls (penicillin: 70.1 vs 0.1 days, p 0.00002). The total non-susceptibility rate was 30% for oral and parenteral (meningitis) penicillin in S. pneumoniae, resistance rates were 1.6% for oxacillin in Staph. aureus and 14.8% for ampicillin in H. influenzae. Susceptibility to antibiotic agents and distribution of capsular types did not differ significantly between both groups. In conclusion, carriage and resistance rates are similar in children with and without SCA. Our data provide the basis to guide empiric therapy of invasive diseases caused by S. pneumoniae, Staph. aureus and H. influenza in children in Gabon.

Clonal structure of Staphylococcus aureus colonizing children with sickle cell anaemia and healthy controls.

Children with sickle cell anaemia (SCA) might carry hospital-associated bacterial lineages due to frequent hospital stays and antibiotic treatments. In this study we compared Staphylococcus aureus from SCA patients (n=73) and healthy children (n=143) in a cross-sectional study in Gabon. S. aureus carriage did not differ between children with SCA (n=34, 46∙6%) and controls matched for age, residence and sex (n=67, 46∙9%). Both groups shared similar S. aureus genotypes. This finding points towards a transmission of S. aureus between both groups in the community. We conclude that resistance rates from population-based studies with healthy participants could therefore also be used to guide treatment and prophylaxis of endogenous infections in children with SCA despite a different selection pressure.

Point and period prevalences of eczema in rural and urban schoolchildren in Ghana, Gabon and Rwanda.

BACKGROUND: Eczema is a growing problem in Africa, particularly amongst children. OBJECTIVES: To investigate the point-prevalences of eczema by physical examination in schoolchildren living in rural and urban areas and with different socioeconomic backgrounds in Ghana, Gabon and Rwanda. In Ghana period-prevalences were also estimated by questionnaire and compared with the point-prevalences. METHODS: In total, 4839 schoolchildren in Ghana, Gabon and Rwanda were seen by at least one dermatologist. The point-prevalences of eczema were estimated on the basis of physical examination. Period-prevalences were measured in Ghana with questionnaire based-interviews adapted from the International Study of Asthma and Allergies in Childhood (ISAAC). RESULTS: The point-prevalences were 1.5% and 1.6% in the two Ghanaian studies; 4% in Gabon and 0.8% in Rwanda. The period-prevalences were 2.6% and 4.4% in the two Ghanaian studies. The prevalences of eczema were not significantly different when comparing the urban and rural groups as well as the different socioeconomic levels. The sensitivity and positive predictive value to identify eczema cases based on the questionnaires compared to the diagnoses by physical examination were only 33% and 22% in the first Ghanaian study and 10% and 4% in the second Ghanaian study respectively. CONCLUSIONS: The point-prevalences of eczema in the three African countries studied were low compared with industrialized countries. Physical examination by a dermatologist is still the gold standard to identify eczema cases because the sensitivity and the positive predictive value to identify eczema cases with questionnaires were low in the two Ghanaian studies.

Virulence factors and genotypes of Staphylococcus aureus from infection and carriage in Gabon.

Staphylococcus aureus isolates from developed countries have been extensively analyzed with respect to their virulence patterns and clonal relatedness but there is only sparse information on the molecular diversity of S. aureus isolates from Africa. In particular, little is known about S. aureus isolates from asymptomatic carriers compared with isolates causing infections. From 2008 to 2010, we prospectively collected S. aureus isolates from asymptomatic carriers and infections in Lambaréné, Gabon, Central Africa. For these isolates, we determined major virulence factors, and performed multilocus sequence typing (MLST) and spa typing. Among 163 S. aureus isolates from asymptomatic carriers, we found the MLST clonal complexes (CCs) 5, 6, 7, 8, 9, 15, 25, 30, 45, 88, 101, 121 and 152; 3.7% were methicillin-resistant (MRSA). The clinical isolates were associated with CCs 5, 8, 9, 15, 88, 121 and 152; 11% were MRSA. Sequence types 1 and 88 were significantly associated with infection and sequence type 508 was associated with carriage. Remarkably, there was a high prevalence of Panton-Valentine leukocidin (PVL) -encoding genes both in disease-related isolates (57.4%) and in carrier isolates (40.5%). We found differences in the clonal structure and virulence pattern of Gabonese S. aureus isolates from asymptomatic carriers and infections. Of note, S. aureus isolates from Gabon show a very high prevalence of PVL-encoding genes, which exceeds the rates observed for developed countries.

Prevalence and causative fungal species of tinea capitis among schoolchildren in Gabon.

Tinea capitis is endemic among schoolchildren in tropical Africa. The objective was to determine the prevalence of symptomatic tinea capitis in schoolchildren in Gabon. A cross-sectional study was conducted with 454 children aged 4-17 years, attending a rural school and an urban school. The diagnosis of tinea capitis was based on clinically manifest infection, direct microscopic examination using 20% potassium hydroxide (KOH) solution and fungal culture. Based on clinical examination, 105 (23.1%) of 454 children had tinea capitis. Seventy-four (16.3%) children were positive by direct examination (KOH) and/or fungal culture. The prevalence of tinea capitis depended on the school studied and ranged from 20.4% in the urban school with a higher socioeconomic status to 26.3% in the rural school with a lower socioeconomic status. Similarly, the spectrum of causative species varied between the different schools. Taken the schools together, Trichophyton soudanense (29.4%) was the most prominent species, followed by Trichophyton tonsurans (27.9%) and Microsporum audouinii (25.0%). Clinically manifest tinea capitis is endemic among schoolchildren in the Lambaréné region in Gabon. The prevalence of tinea capitis and the causative species depended on the type of school that was investigated.

Cellular and humoral responses to tetanus vaccination in Gabonese children.

Protection to tetanus is often not optimal in developing countries due to incomplete vaccination schemes, or decreased efficacy of vaccination. In this study we investigated the immunological response to tetanus booster vaccination in school children living in a semi-urban or in a rural area of Gabon. Tetanus-specific total IgG as well as antibody subclasses of the IgG1, IgG2, IgG3 and IgG4 isotype and the avidity of the dominating IgG1 subclass were determined both before and 1 month after the booster vaccination. In addition, tetanus-specific cytokine responses were determined. We found a polarization towards a T helper 1 (Th1) profile in the semi-urban children, whereas the cytokine responses of the rural children showed a T helper 2 (Th2) skewed response. Furthermore, tetanus-specific antibodies of the different IgG subclasses were all increased upon a tetanus booster vaccination and levels of IgG1 and IgG3 were higher in the rural children. In conclusion, a tetanus booster vaccination induced a stronger Th2 over Th1 cytokine profile to tetanus toxoid (TT) in rural children who showed the highest levels of IgG1 and IgG3 anti-TT antibody responses.

Immunologic activity of schistosomal and bacterial TLR2 ligands in Gabonese children.

Schistosomes carry lipid moieties that interact with the immune system. To understand the consequence of interactions in terms of polarizing the cytokine profiles, the effect of two Toll-like receptor-2 (TLR2) activating schistosomal lipid fractions was studied on whole blood from Gabonese children living in a schistosomiasis endemic area. One fraction contained lysophosphatidylserine [monoacylglycerophosphoserine (lysoGPSer)] plus diacylphosphatidylserine [diacylglycerophosphoserine (GPSer)] while the other contained lysoGPSer and only a trace of GPSer. The effect of these schistosomal lipid fractions was compared with the known bacterial TLR2 ligands PAM3CSK4 and MALP-2. PAM3CSK4 and MALP-2 had preferential IL-10-activating capacities, while the fraction containing lysoGPSer plus GPSer had a strong TNF-alpha-inducing capacity. The fraction containing lysoGPSer was neutral with respect to pro- vs. anti-inflammatory effects. When Th1 and Th2 cytokines were analysed, the schistosomal lipid fraction containing lysoGPSer plus GPSer showed a stronger Th2 response compared to PAM3CSK4, MALP-2 and lysoGPSer alone. Therefore, the study indicates that not only TLR2 ligands derived from bacteria or from parasites can generate distinct cytokine profiles but also that the composition of lipid entities reaching the immune system can be important in leading to different immune outcomes. This information may be important for exploitation of immune modulatory molecules.

Cellular and humoral responses to influenza in gabonese children living in rural and semi-urban areas.

BACKGROUND: With the current attention to the pandemic threat of avian influenza viruses, it is recognized that there is little information on influenza in Africa. In addition, the effects of influenza vaccination in African countries could be very different from the effects in regions with less exposure to microorganisms and parasites. METHODS: To monitor the presence of influenza viruses and investigate the immunological responses to influenza vaccination, schoolchildren in semi-urban and rural regions of Gabon were studied. Influenza-specific antibody responses to the 3 strains represented in the vaccine were determined in the serum. Furthermore, cytokine responses were measured after in vitro stimulation of whole blood by influenza antigens, before and after vaccination. RESULTS: Prevaccination titers of antibody against H3N2 were high. At vaccination, the titers of antibody against the 3 influenza strains increased significantly. The anti-H1N1 and anti-B responses after vaccination were weaker in rural schoolchildren than in semi-urban schoolchildren. Influenza-specific cytokine responses were induced within a week, showing significantly lower interferon- gamma and significantly higher interleukin-5 in the children from rural areas. CONCLUSIONS: Prevaccination antibody levels indicated that influenza viruses circulate in Gabon. Altogether, influenza vaccination induces weaker immune responses in a rural population than in a semi-urban population of Gabonese schoolchildren.

Reassessment of the resistance of Plasmodium falciparum to chloroquine in Gabon: implications for the validity of tests in vitro vs. in vivo.

Increasing resistance of Plasmodium falciparum to antimalarial drugs presents a major risk factor for people living in endemic areas of tropical Africa. In Lambaréné, Gabon, regular surveillance of chloroquine sensitivity of P. falciparum in vitro has been carried out since 1992 using the WHO standard microtest. Results indicated that from 1994 onwards chloroquine resistance in vitro decreased significantly and that by 2000, about 70% of parasite isolates seemed to be sensitive to chloroquine in vitro. In 2001, we conducted a clinical study to reassess the efficacy of chloroquine in vivo for the treatment of uncomplicated P. falciparum malaria. Twenty-six patients aged 4-15 years were included in this study. Most unexpectedly, the study demonstrated high-grade resistance to chloroquine in vivo (failure rate on day 28 of 100%). As a consequence, tests of parasite susceptibility to chloroquine in vitro were repeated using the same protocol except for the replacement of previously used commercially available predosed WHO culture plates by independently dosed plates. All tested P. falciparum isolates were highly resistant to chloroquine, correlating well with our clinical findings. We concluded that high level resistance of P. falciparum to chloroquine persists in the study area. Neglect or absence of quality controls of essential test material can lead to invalid study results and wrong conclusions and should always be suspected in the case of major fluctuations in the sensitivity patterns of an antimalarial drug in vitro. In addition, our results highlight the supreme value of tests in vivo in providing reliable estimates of the efficacy of an antimalarial in a specific area.