Don de sang au poste de collecte et de distribution des produits sanguins de Kara, au nord Togo. : Blood donation at Kara blood collection and distribution center in northern Togo

Problématique et objectifLa pénurie de sang est quasi constante au Togo particulièrement dans la partie septentrionale du pays. La connaissance du profil des donneurs permettrait d’améliorer les stratégies de promotion du don de sang pour une meilleure disponibilité des produits sanguins labiles. Le but de cette étude était d’établir le profil épidémiologique des donneurs de sang à Kara.Matériel et MéthodesC’était une étude prospective allant du 2 janvier 2018 au 30 mars 2019 qui s’est déroulée au poste de collecte et de distribution des produits sanguins (banque de sang) de Kara. Durant cette période, tous les candidats au don de sang déclarés aptes ont été recrutés et inclus dans l’étude. Il s’est agi de donneurs de sang des deux sexes âgés de 18 à 55 ans. Les donneurs séronégatifs au VIH, à l’hépatite B, à l’hépatite C et à la syphilis ont été suivis sur une période de douze mois.Résultats :L’âge médian des 681 donneurs était de 25 ans. On a noté une prédominance masculine; sex ratio à 5,08. La majorité était des anciens donneurs (86,20%). Les élèves et les étudiants représentaient 79,88%. Le groupe sanguin O était le plus représenté (46,84%) suivi du groupe B (33,48%). Le rhésus négatif représentait 8,52%. La séroprévalence de l’hépatite B et C était respectivement de 2,35 % et 0,29 %. Il n’y avait aucun cas de VIH ni de syphilis à l’inclusion. Un (01) cas de séroconversion au VIH a été observé au cours du suivi sur douze mois. La proportion de donneurs séronégatifs qui avaient refait au moins un second don en un an était de 86,74% parmi les anciens donneurs contre 65,43 % chez les nouveaux donneurs (p= 0,0005).ConclusionLa majorité des donneurs de sang à Kara sont des élèves et étudiants de sexe masculin. Cette situation pourrait expliquer l’aggravation de la pénurie de sang pendant les vacances scolaires et universitaires. Les stratégies de promotion du don de sang doivent cibler les autres couches socio-professionnelles tout en encourageant les élèves et les étudiants à continuer à donner le sang pendant les vacances. Les taux faibles de séroprévalences des marqueurs infectieux de notre étude confirment l’intérêt de la fidélisation des donneurs de sang. Problem and objectiveThe shortage of blood is almost constant in Togo, particularly in the northern part of the country. Knowing the profile of donors would improve blood donation promotion strategies for better availability of labile blood products. The aim of this study was to establish the epidemiological profile of blood donors in Kara.Material and methodsIt was a prospective study from January 2, 2018 to March 30, 2019 that took place at the Kara blood bank. During this period, all candidates for blood donation declared suitable were recruited and included in the study. It involved 681 blood donors of both sexes aged 18 to 55 years. HIV, hepatitis B, hepatitis C and syphilis negative donors were followed up over a period of twelve months.Results:The median age of donors was 25 years. A male predominance was noted; sex ratio at 5.08. The majority were former donors (86.20%). Pupils and students accounted for 79.88%. Blood group O was the most represented (46.84%) followed by group B (33.48%). Rh negative accounted for 8.52%. The seroprevalence of hepatitis B and C was 2.35% and 0.29% respectively. There were no cases of HIV or syphilis at baseline. One case of HIV seroconversion was observed during the 12-month follow-up. The proportion of seronegative donors who had made at least a second donation in one year was 86.74% among former donors against 65.43% among first-time donors (p= 0.0005).ConclusionThe majority of blood donors in Kara are male pupils and students. This situation may explain the aggravation of the blood shortage during school and university holidays. Strategies to promote blood donation must target other socio-professional strata while encouraging pupils and students to continue donating blood during the holidays. The low seroprevalence rates of the infectious markers in our study confirm the importance of retaining blood donors

Mansonella perstans, Onchocerca volvulus and Strongyloides stercoralis infections in rural populations in central and southern Togo

Background: Mansonella perstans, Onchocerca volvulus and Strongyloides stercoralis are widespread helminth parasites in the tropics. Their distribution remains difficult to determine as it may change during national disease control programs and with regional mass drug administration (MDA). Epidemiological surveys are of importance to evaluate the geographical distribution of these helminth parasites and the diseases they may cause, however, up to date epidemiological evaluations on M. perstans and S. stercoralis in Togo are rare, and surveys on O. volvulus are important especially under the aspect of MDA of ivermectin which is performed since decades. Methods: Dry blood samples (n = 924) were collected from rural populations in the Régions Central and Plateaux in Togo, and analyzed by parasite-specific real-time PCR and ELISA techniques. Results: Dry blood samples from 733 persons where investigated by real-time PCR tested for DNA of blood-circulating M. perstans microfilaria, and a prevalence of 14.9% was detected. Distinct differences were observed between genders, positivity was higher in men increasing with age, and prevalence was highest in the Région Plateaux in Togo. IgG4 responses to O. volvulus antigen (OvAg) were studied in 924 persons and 59% were found positive. The distribution of parasite infestation between age and gender groups was higher in men increasing with age, and regional differences were detected being highest in the Région Plateaux. The diagnostic approach disclosed 64,5% positive IgG4 responses to S. stercoralis infective third-stage larvae-specific antigen (SsL3Ag) in the surveyed regions. Antigen cross reactivity of SsL3Ag with parasite co-infections may limit the calculated prevalence. Singly IgG4 positive for SsL3Ag were 13.9%, doubly positive for OvAg and SsL3Ag were 35.5% and triply positive for M. perstans, O. volvulus and S. stercoralis were 9.9%. Conclusions: Mansonelliasis, onchocerciasis and strongyloidiasis remain prevalent in the surveyed regions, yet with local differences. Our observations suggest that transmission of M. perstans, O. volvulus and S. stercoralis may be ongoing. The degree of positive test results in the examined rural communities advocate for the continuation of MDA with ivermectin and albendazole, and further investigations should address the intensity of transmission of these parasites. Keywords: Onchocerca volvulus, Mansonella perstans, Strongyloides stercoralis, Onchocerciasis, Mansonelliasis, Strongyloidiasis, Togo, Prevalenc

<i>Onchocerca volvulus</i> infection and serological prevalence, ocular onchocerciasis and parasite transmission in northern and central Togo after decades of <i>Simulium damnosum</i> s.l. vector control and mass drug administration of ivermectin

<div><p>Background</p><p>Mass drug administration (MDA) of ivermectin has become the main intervention to control onchocerciasis or “river blindness”. In Togo, after many years of MDA, <i>Onchocerca volvulus</i> infection has declined dramatically, and elimination appears achievable, but in certain river basins the current situation remains unknown. We have conducted parasitological, serological, ophthalmological, and entomological assessments in northern and central Togo within the river basins of Ôti, Kéran and Mô.</p><p>Methodology/Principal findings</p><p>Examinations were completed in 1,455 participants from 11 onchocerciasis sentinel villages, and <i>O</i>. <i>volvulus</i> transmission by <i>Simulium damnosum</i> sensu lato (s.l.) was evaluated. In children (aged 1–10 years), the prevalence of microfilariae (Mf) was 2.3% and in adults it ranged from 5.1 to 13.3%. Positive IgG4 responses to <i>O</i>. <i>volvulus</i> adult (crude) worm antigen (OvAg) and the recombinant Ov16 antigen were in all-ages 48.7% and 34.4%, and 29.1% and 14.9% in children, respectively. In the river basin villages of Kéran, Mô and Ôti, the IgG4 seroprevalences to OvAg in children were 51.7%, 23.5% and 12.7%, respectively, and to the Ov16 antigen 33.3% (Kéran) and 5.2% (Ôti). Onchocerciasis ocular lesions (punctate keratitis, evolving iridocyclitis and chorioretinitis) were observed in children and young adults. <i>O</i>. <i>volvulus</i>-specific DNA (Ov150) was detected by poolscreen in vector samples collected from Tchitchira/Kéran(22.8%), Bouzalo/Mô(11.3%), Baghan/Mô(2.9%) and Pancerys/Ôti(4.9%); prevalences of <i>O</i>. <i>volvulus</i> infection in <i>S</i>. <i>damnosum</i> s.l. were, respectively, 1%, 0.5%, 0.1% and 0.2%.</p><p>Conclusions/Significance</p><p>In the northern and central river basins in Togo, interruption of <i>O</i>. <i>volvulus</i> transmission has not yet been attained. Patent <i>O</i>. <i>volvulus</i> infections, positive antibody responses, progressive ocular onchocerciasis were diagnosed, and parasite transmission by <i>S</i>. <i>damnosum</i> s.l. occurred close to the survey locations. Future interventions may require approaches selectively targeted to non-complying endemic populations, to the seasonality of parasite transmission and national onchocerciasis control programs should harmonize cross-border MDA as a coordinated intervention.</p></div

Collection of <i>Simulium damnosum</i> s.l. at the catch point at the Mô river (village of Bouzalo) caught per person (one day per week).

<p>The annual biting rate (ABR) from January 2016 until December 2016 was calculated by multiplying the number of blackflies caught daily by the number of days per week for each month to add up to 12 months. Collections were conducted from 7am to 6pm with alternating fly catchers every two hours as described in Material and Methods.</p

Locations of the villages surveyed and the <i>Simulium</i> collection sites in the three river basins (Ôti, Kéran, Mô) in Savanes, Kara and central regions in Togo.

<p>For an explanation of the control measures and their timings in the northern and central areas of Togo, including SIZ, see legend of <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0006312#pntd.0006312.g001" target="_blank">Fig 1</a>.</p

Spearman’s rank correlation analyses of ocular pathologies and visual acuity of the right eye (RE) in the survey participants and significant associations (p<0.05).

<p>Spearman’s rank correlation analyses of ocular pathologies and visual acuity of the right eye (RE) in the survey participants and significant associations (p<0.05).</p

<i>Onchocerca volvulus</i> microfilarial prevalence (% Mf-positive) by age and sex groups in the survey participants from NOCP sentinel villages in central and northern Togo.

<p>The number of examined participants, the Mf-positive status and the percentage of Mf-positive individuals are shown. From n = 41 study participants the age is missing. The 95% confidence intervals (95% CI, Wilson score interval) of the prevalence values are indicated in square brackets. (* significant differences between female and male survey participation).</p

Ocular pathologies and visual acuity in study participants (n = 1,172) according to age.

<p>The ocular pathologies, their grades of evolution and extent were classified as described previously [<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0006312#pntd.0006312.ref012" target="_blank">12</a>].</p

Prevalence of microfilariae (Mf) of <i>Onchocerca volvulus</i> in sentinel villages (n = 363) of the National Onchocerciasis Control Programme (NOCP) in Togo.

<p>Regular epidemiological surveys (n = 957) were conducted by the NOCP over a 37-year period (1976–2014) in onchocerciasis endemic villages, and from each participant (n = 193,742) a skin biopsy was taken from the left and right iliac crest and the emerging Mf were counted after snip incubation. The graph shows the microfilarial prevalence (median, minimum, maximum, in %) as detected during the annual surveys. Anti-vectorial interventions were applied since 1976, whereas the central regions were incorporated into the Programme in 1987. Since 1988, vector control measures were supplemented by MDA with ivermectin. Initially MDA was applied mainly by mobile teams; during some years of the early 1990’s, aerial larvicide application was suspended in several river basins. In the northern territories (SIZ) vector control and intensified ivermectin distribution was continued after OCP’s closure in 2002. Special interventions in the post-OCP period included continued aerial larvicide application for five additional years (2003–2007) and biannual ivermectin MDA until the end of 2012.</p

<i>Onchocerca volvulus</i> adult worm (OvAg) and recombinant Ov16 antigen-specific IgG4 reactivity (optical densities; OD) in participants and positive and negative IgG4 responses in age groups.

<p>In A and C the data on antigen-specific IgG4 reactivity are shown as mean optical densities (ODs) with 95% confidence intervals for the means (diamonds). The data presented in box plots show the median OD per age group with the 25% and 75% quartiles and the 1.5x of the interquartile range. In B and D the antigen-specific-IgG4 positive and negative responses in age groups are indicated (in %).</p