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M'Bondoukwé NP, Owono-Medang M, Moussavou-Boussougou MN, Akoue Y, Migueba V, Bulaev D, Neven A, James LAJ, Ntsame Ella SA, Mawili-Mboumba DP, Atsame J, Vaillant M, Bouyou Akotet MK. Low diagnostic performance of thick blood smears of 50 µl in comparison with direct examination of 10 µl blood and the leukoconcentration technique of 5ml blood among loiasis-suspected patients with low microfilaremia in Gabon, Central Africa, using the STARD-BLCM guidelines. Parasit Vectors 2024; 17:138. [PMID: 38491557 PMCID: PMC10943916 DOI: 10.1186/s13071-023-06089-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 12/08/2023] [Indexed: 03/18/2024] Open
Abstract
BACKGROUND The aim of this study was to determine performance indicators of thick blood smears of 50 µl (TBS-50), following the Standards for the Reporting of Diagnostic Accuracy Studies-Bayesian Latent Class Model (STARD-BLCM) guidelines. TBS-50 was compared with two common parasitological techniques-direct examination of 10 µl blood and a leukoconcentration of 5 ml-for the diagnosis of microfilaremic loiasis. METHODS The study population was recruited among patients of the Department of Parasitology-Mycology-Tropical Medicine over a period of 1 year. Age, sex, symptoms, and eosinophilia variables were recorded from laboratory registers and medical files. Direct examination of 10 µl of blood, TBS-50, and the leukoconcentration technique with 5 ml of blood were performed for each patient. The classical formula and BLCM were used to determine the diagnostic accuracy of the three techniques as well as the prevalence of microfilaremic loiasis. Three models were built within the framework of BLCM-the BLCM model I and alternative models II and III-for sensitivity analysis. RESULTS In total, 191 patients consented to be included. The direct blood examination and TBS-50 yielded comparable qualitative and quantitative results. Hence, they are reported together. The prevalence of Loa loa microfilaremia was 9.4% (95% CI 5.7-14.5; n = 18/191) with direct blood examination/TBS-50 and 12.6% [8.2-18.1] (n = 24/191) for leukoconcentration. Comparing TBS-50 with the leukoconcentration method using the classical formula, the sensitivity was 75.0% [53.3-90.2], specificity was 100.0% [97.8-100.0], the positive predictive value was 100.0% [81.5-100.0], and the negative predictive value was 96.5% [92.6-98.7]. The prevalence of microfilaremic loiasis was estimated at 9.7% [6.2-13.7] using BLCM model I. The outputs of BLCM model I showed sensitivity of 78.9% [65.3-90.3], specificity of 100.0% [99.3-100.0], a positive predictive value of 99.1% [87.2-100.0], and a negative predictive value of 93.0% [87.3-97.7] for direct blood examination/TBS-50. CONCLUSIONS TBS-50 demonstrates low sensitivity relative to two other techniques. In one in five cases, the result will be falsely declared negative using these methods. However, this method can be deployed with limited funds.
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Affiliation(s)
- Noé Patrick M'Bondoukwé
- Department of Parasitology-Mycology-Tropical Medicine, Faculty of Medicine, Université des Sciences de la Santé, 4009, Libreville, Gabon.
| | - Matthieu Owono-Medang
- Department of Parasitology-Mycology-Tropical Medicine, Faculty of Medicine, Université des Sciences de la Santé, 4009, Libreville, Gabon
| | - Marie Noëlle Moussavou-Boussougou
- Department of Parasitology-Mycology-Tropical Medicine, Faculty of Medicine, Université des Sciences de la Santé, 4009, Libreville, Gabon
| | - Yvan Akoue
- Department of Parasitology-Mycology-Tropical Medicine, Faculty of Medicine, Université des Sciences de la Santé, 4009, Libreville, Gabon
| | - Valentin Migueba
- Department of Parasitology-Mycology-Tropical Medicine, Faculty of Medicine, Université des Sciences de la Santé, 4009, Libreville, Gabon
| | - Dmitry Bulaev
- Competence Centre for Methodology and Statistics, Luxembourg Institute of Health, 1A-B Rue Thomas Edison, 1445, Strassen, Luxembourg
| | - Anouk Neven
- Competence Centre for Methodology and Statistics, Luxembourg Institute of Health, 1A-B Rue Thomas Edison, 1445, Strassen, Luxembourg
| | - Luice Aurtin Joel James
- Department of Parasitology-Mycology-Tropical Medicine, Faculty of Medicine, Université des Sciences de la Santé, 4009, Libreville, Gabon
| | | | - Denise Patricia Mawili-Mboumba
- Department of Parasitology-Mycology-Tropical Medicine, Faculty of Medicine, Université des Sciences de la Santé, 4009, Libreville, Gabon
| | - Julienne Atsame
- Programme de Lutte Contre les Maladies Parasitaires, Ministère de la Santé du Gabon, Libreville, Gabon
| | - Michel Vaillant
- Competence Centre for Methodology and Statistics, Luxembourg Institute of Health, 1A-B Rue Thomas Edison, 1445, Strassen, Luxembourg
| | - Marielle Karine Bouyou Akotet
- Department of Parasitology-Mycology-Tropical Medicine, Faculty of Medicine, Université des Sciences de la Santé, 4009, Libreville, Gabon
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Moutongo Mouandza R, Mourou JR, Moutombi Ditombi B, Roger Sibi Matotou H, Ekomi B, Bouyou-Akotet MK, Mawili-Mboumba DP. Sociodemographics, Clinical Factors, and Biological Factors Associated with Loiasis in Endemic Onchocerciasis Areas in Southern Gabon. Am J Trop Med Hyg 2023; 109:850-857. [PMID: 37339766 PMCID: PMC10551092 DOI: 10.4269/ajtmh.22-0558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Accepted: 04/22/2023] [Indexed: 06/22/2023] Open
Abstract
To implement the appropriate strategies for scale-up interventions to eliminate onchocerciasis without severe adverse events, clinical and biological factors associated with loiasis were analyzed in onchocerciasis-endemic areas. Blood was collected from volunteers after examination by a physician. Detection of microfilariae and measurement of Ov16 IgG4 were performed using direct microscopic examination of blood and onchocerciasis rapid test detection, respectively. Areas with sporadic, hypoendemic, and hyperendemic onchocerciasis endemicity were found. Participants with microfilaremia were considered microfilaremic, and those without microfilaremia were seen as amicrofilaremic. Of the 471 study participants, 40.5% (n = 191) had microfilariae. Among them, Mansonella spp. was the most common (78.2%, n = 147), followed by Loa loa (41.4%, n = 79). The association between the two species represented 18.3% (n = 35). The specific immunoglobulins of Onchocerca volvulus were detected in 24.2% of participants (n = 87/359). Overall prevalence of L. loa was 16.8%. Hypermicrofilaremia was found in 3% (N = 14), and one participant had more than 30,000 microfilaremiae per milliliter. The frequency of L. loa did not vary according to the level of onchocerciasis transmission. Pruritus was the most common clinical sign (60.5%, n = 285) reported, mainly in microfilaremic participants (72.2%, n = 138/191). The prevalence of L. loa microfilaria in the study population was below the threshold at risk for the occurrence of serious side effects due to ivermectin. Clinical manifestations frequently observed could be exacerbated by microfilaremia in areas where onchocerciasis transmission is high.
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Affiliation(s)
- Reinne Moutongo Mouandza
- Department of Parasitology-Mycology and Tropical Medicine, Faculty of Medicine, Université des Sciences de la Santé, Libreville, Gabon
| | - Jean Romain Mourou
- Department of Parasitology-Mycology and Tropical Medicine, Faculty of Medicine, Université des Sciences de la Santé, Libreville, Gabon
| | - Bridy Moutombi Ditombi
- Department of Parasitology-Mycology and Tropical Medicine, Faculty of Medicine, Université des Sciences de la Santé, Libreville, Gabon
| | - Hadry Roger Sibi Matotou
- Department of Parasitology-Mycology and Tropical Medicine, Faculty of Medicine, Université des Sciences de la Santé, Libreville, Gabon
| | - Bernadette Ekomi
- Department of Parasitology-Mycology and Tropical Medicine, Faculty of Medicine, Université des Sciences de la Santé, Libreville, Gabon
| | - Marielle Karine Bouyou-Akotet
- Department of Parasitology-Mycology and Tropical Medicine, Faculty of Medicine, Université des Sciences de la Santé, Libreville, Gabon
| | - Denise Patricia Mawili-Mboumba
- Department of Parasitology-Mycology and Tropical Medicine, Faculty of Medicine, Université des Sciences de la Santé, Libreville, Gabon
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Albanus C, Ewers N, Probst-Kepper M, Schmiedel S, Prüfer-Krämer L. Vier deutsche Patienten mit Loa-loa-Filariasis bei Missionstätigkeit im Osten Kameruns. FLUGMEDIZIN · TROPENMEDIZIN · REISEMEDIZIN - FTR 2023. [DOI: 10.1055/a-1999-1791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
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Campillo JT, Hemilembolo MC, Louya F, Bikita P, Pion SDS, Boussinesq M, Missamou F, Chesnais CB. Temporal variability of Loa loa microfilaraemia. Parasit Vectors 2023; 16:23. [PMID: 36691079 PMCID: PMC9869825 DOI: 10.1186/s13071-022-05612-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 12/06/2022] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND The diurnal periodicity of Loa loa microfilaraemia is well known but few studies have documented the short- and long-term stability of microfilarial density. It seems stable over time at the community level, but significant variations have been observed at the individual level. METHODS We assessed the temporal variability of L. loa microfilaraemia at 5-day, 1-month and 16-month intervals and analyzed the influence of sex, age, level of microfilaraemia, temperatures and time of sampling on this variability. RESULTS At the community level, L. loa microfilaraemia is very stable over time at 5-day, 1-month and 16-month intervals (Pearson correlation coefficients of 0.92, 0.91 and 0.78, respectively, all three with P < 0.001). However, some individuals had significant variations of up to ± 50% of their initial microfilaraemia at 5-day (33.0%), 1-month (36.5%) and 16-month (62.6%) intervals, even in individuals with an initial microfilaraemia density > 20,000 mf/ml (7.7, 23.1 and 41.4%, respectively, for 5 days, 1 month and 16 months). We do not highlight any external factors that have a major impact on this variability. CONCLUSION Although at the community level, microfilaria density is very stable, we highlight some individuals with large variations in both the short and long term, which may have an important impact on onchocerciasis control campaigns and longitudinal studies evaluating the impact of an intervention on L. loa microfilaraemia.
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Affiliation(s)
- Jérémy T. Campillo
- grid.121334.60000 0001 2097 0141TransVIHMI, INSERM Unité 1175, Institut de Recherche pour le Développement (IRD), Université de Montpellier, Montpellier, France
| | - Marlhand C. Hemilembolo
- grid.121334.60000 0001 2097 0141TransVIHMI, INSERM Unité 1175, Institut de Recherche pour le Développement (IRD), Université de Montpellier, Montpellier, France ,Programme National de Lutte contre l’Onchocercose, Direction de l’Épidémiologie et de la Lutte contre la Maladie, Ministère de la Santé et de la Population, Brazzaville, Republic of Congo
| | - Frédéric Louya
- Programme National de Lutte contre l’Onchocercose, Direction de l’Épidémiologie et de la Lutte contre la Maladie, Ministère de la Santé et de la Population, Brazzaville, Republic of Congo
| | - Paul Bikita
- Programme National de Lutte contre l’Onchocercose, Direction de l’Épidémiologie et de la Lutte contre la Maladie, Ministère de la Santé et de la Population, Brazzaville, Republic of Congo
| | - Sébastien D. S. Pion
- grid.121334.60000 0001 2097 0141TransVIHMI, INSERM Unité 1175, Institut de Recherche pour le Développement (IRD), Université de Montpellier, Montpellier, France
| | - Michel Boussinesq
- grid.121334.60000 0001 2097 0141TransVIHMI, INSERM Unité 1175, Institut de Recherche pour le Développement (IRD), Université de Montpellier, Montpellier, France
| | - François Missamou
- Programme National de Lutte contre l’Onchocercose, Direction de l’Épidémiologie et de la Lutte contre la Maladie, Ministère de la Santé et de la Population, Brazzaville, Republic of Congo
| | - Cédric B. Chesnais
- grid.121334.60000 0001 2097 0141TransVIHMI, INSERM Unité 1175, Institut de Recherche pour le Développement (IRD), Université de Montpellier, Montpellier, France
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Integrated xenosurveillance of Loa loa, Wuchereria bancrofti, Mansonella perstans and Plasmodium falciparum using mosquito carcasses and faeces: A pilot study in Cameroon. PLoS Negl Trop Dis 2022; 16:e0010868. [PMID: 36322515 PMCID: PMC9629651 DOI: 10.1371/journal.pntd.0010868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 10/03/2022] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Community presence of loiasis must be determined before mass drug administration programmes for lymphatic filariasis and onchocerciasis can be implemented. However, taking human blood samples for loiasis surveillance is invasive and operationally challenging. A xenosurveillance approach based on the molecular screening of mosquitoes and their excreta/feces (E/F) for Loa loa DNA may provide a non-invasive method for detecting the community presence of loiasis. METHODS We collected 770 wild mosquitoes during a pilot study in a known loiasis transmission area in Mbalmayo, Cameroon. Of these, 376 were preserved immediately while 394 were kept in pools to collect 36-hour E/F samples before processing. Carcasses and E/F were screened for L. loa DNA. To demonstrate this method's potential for integrated disease surveillance, the samples were further tested for Wuchereria bancrofti, Mansonella perstans, and Plasmodium falciparum. RESULTS Despite limited sample numbers, L. loa DNA was detected in eight immediately-stored mosquitoes (2.13%; 95% CI 1.08 to 4.14), one carcass stored after providing E/F (0.25%; 95% CI 0.04 to 1.42), and three E/F samples (estimated prevalence 0.77%; 95% CI 0.15 to 2.23%). M. perstans and P. falciparum DNA were also detected in carcasses and E/F samples, while W. bancrofti DNA was detected in E/F. None of the carcasses positive for filarial worm DNA came from pools that provided a positive E/F sample, supporting the theory that, in incompetent vectors, ingested parasites undergo a rapid, complete expulsion in E/F. CONCLUSIONS Mosquito xenosurveillance may provide a useful tool for the surveillance of loiasis alongside other parasitic diseases.
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Dieki R, Nsi-Emvo E, Akue JP. The Human Filaria Loa loa: Update on Diagnostics and Immune Response. Res Rep Trop Med 2022; 13:41-54. [PMID: 35936385 PMCID: PMC9355020 DOI: 10.2147/rrtm.s355104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 06/03/2022] [Indexed: 11/24/2022] Open
Abstract
Loa loa loiasis was considered an anecdotal disease 30 years ago. Its spread in Equatorial Africa and the side effects associated with mass drug administration programs against filariasis in co-endemic areas have drawn the attention of the international research community. Progress in research conducted to date has provided insight into the immunobiology of this parasite. An interesting finding reported in several studies is that 70% of individuals with loiasis do not carry microfilariae in their blood, and 30% are microfilaremic, suggesting the involvement of several immunological mechanisms, as shown by elevated specific IgG4 and IgE levels signifying a potential cross-linking mechanism between the two isotypes via L. loa antigen to prevent allergy. A mechanism of anergy in the appearance of microfilariae in the peripheral blood results in immunological unresponsiveness in individuals with microfilariae. There is an interaction between other pathogens (parasites, bacteria, viruses) in individuals co-infected with L. loa. The strong antigen cross-reactivity between L. loa and lymphatic filarial worms warrants a re-evaluation of the distribution of the latter in co-endemic regions. The mechanism of concomitant immunity observed in the elimination of microfilariae or infective larvae (third-stage larvae, L3) may be used for the conception of an immunoprophylactic strategy.
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Affiliation(s)
- Roland Dieki
- Department of Parasitology, International Centre of Medical Research of Franceville, Franceville, Gabon
- Department of Chemistry, Université des Sciences et Techniques de Masuku (USTM), Franceville, Gabon
| | - Edouard Nsi-Emvo
- Department of Chemistry, Université des Sciences et Techniques de Masuku (USTM), Franceville, Gabon
| | - Jean Paul Akue
- Department of Parasitology, International Centre of Medical Research of Franceville, Franceville, Gabon
- Correspondence: Jean Paul Akue, Department of Parasitology, International Centre of Medical Research of Franceville, Franceville, BP 769, Gabon, Email
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Akhoundi M, Marteau A, Mechaï F, Mantelet S, Izri A. Molecular characterization and genetic diversity of Loa loa parasites responsible of a long-delayed filarial infection in an immigrant patient inhabited in Paris. Microb Pathog 2021; 158:105101. [PMID: 34303811 DOI: 10.1016/j.micpath.2021.105101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 07/11/2021] [Accepted: 07/15/2021] [Indexed: 10/20/2022]
Abstract
A 21-year-old young boy who lived alone since one year and a half ago in Paris was referred due to severe vertigo. He is originally from Ivory Coast but lived from 2011 to 2017 in Douala city in west of Cameroon. Beside vertigo, he complained from headache, sudden abdominal pain and edema in both left and right forearms for about two years. General examination demonstrated a healthy condition with no subcutaneous nodules and swelling on any other part of the body, not splenomegaly or lymphadenopathy. Moreover, the eyes were normal with clear lens. Blood count analysis revealed a hypereosinophilia (2670*106/L, N: <500*106/L). A couple of direct and May-Grunwald-Giemsa stained smears, analyzed by microscopy revealed the semitransparent cylindrical worms with almost 300 μm length and 45 μm width identified as Loa loa. The identity of the worm was then confirmed by bidirectional sequencing of 450 bp fragment of internal transcribed spacer 1 (ITS1-rDNA). Based on Neighbor-Joining phylogenetic tree, our isolate was clustered tightly with other few Loa species from Gabon in the same clade. No hybrid was observed among processed sequences since all species groups were discriminated separately. In the current case, he was originally from Ivory Coast but absence of medical and epidemiological evidences as well as the residency of our patient for 6 years in Cameroon made us suspicious that the patient has been most likely infected by L. loa worms in this country. The patient was treated by a couple of ivermectin (200 µg/kg for 3 days) and diethylcarbamazine (3 mg/kg, 2 times per day for 4 weeks) and a favorable evolution was observed within few weeks. Regarding at least one year and a half interval between the probable Loa loa infection in Cameroon and diagnosis, Loa loa worms are competent to persist in the human host for several years. Consequently, the clinicians should be aware of this parasitosis among the travelers or immigrants coming from endemic regions in Africa.
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Affiliation(s)
- Mohammad Akhoundi
- Parasitology-Mycology Department, Avicenne Hospital, AP-HP, Bobigny, France.
| | - Anthony Marteau
- Parasitology-Mycology Department, Avicenne Hospital, AP-HP, Bobigny, France
| | - Frederic Mechaï
- Infectious Diseases Department, Avicenne Hospital, AP-HP, Bobigny, France
| | - Stéphane Mantelet
- Parasitology-Mycology Department, Avicenne Hospital, AP-HP, Bobigny, France
| | - Arezki Izri
- Parasitology-Mycology Department, Avicenne Hospital, AP-HP, Bobigny, France; Unité des Virus Émergents (UVE: Aix-Marseille Univ-IRD 190-Inserm 1207-IHU Méditerranée Infection), Marseille, France
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