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Ngay Lukusa I, Van Reet N, Mumba Ngoyi D, Miaka EM, Masumu J, Patient Pyana P, Mutombo W, Ngolo D, Kobo V, Akwaso F, Ilunga M, Kaninda L, Mutanda S, Muamba DM, Valverde Mordt O, Tarral A, Rembry S, Büscher P, Lejon V. Trypanosome SL-RNA detection in blood and cerebrospinal fluid to demonstrate active gambiense human African trypanosomiasis infection. PLoS Negl Trop Dis 2021; 15:e0009739. [PMID: 34534223 PMCID: PMC8480889 DOI: 10.1371/journal.pntd.0009739] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 09/29/2021] [Accepted: 08/17/2021] [Indexed: 11/21/2022] Open
Abstract
Background Spliced Leader (SL) trypanosome RNA is detectable only in the presence of live trypanosomes, is abundant and the Trypanozoon subgenus has a unique sequence. As previously shown in blood from Guinean human African trypanosomiasis (HAT) patients, SL-RNA is an accurate target for diagnosis. Detection of SL-RNA in the cerebrospinal fluid (CSF) has never been attempted. In a large group of Congolese gambiense HAT patients, the present study aims i) to confirm the sensitivity of SL-RNA detection in the blood and; ii) to assess the diagnostic performance of SL-RNA compared to trypanosome detection in CSF. Methodology/Principal findings Blood and CSF from 97 confirmed gambiense HAT patients from the Democratic Republic of Congo were collected using PAXgene blood RNA Tubes. Before RNA extraction, specimens were supplemented with internal extraction control RNA to monitor the extraction, which was performed with a PAXgene Blood RNA Kit. SL-RNA qPCR was carried out with and without reverse transcriptase to monitor DNA contamination. In blood, 92/97 (94.8%) HAT patients tested SL-RNA positive, which was significantly more than combined trypanosome detection in lymph and blood (78/97 positive, 80.4%, p = 0.001). Of 96 CSF RNA specimens, 65 (67.7%) were SL-RNA positive, but there was no significant difference between sensitivity of SL-RNA and trypanosome detection in CSF. The contribution of DNA to the Cq values was negligible. In CSF with normal cell counts, a fraction of SL-RNA might have been lost during extraction as indicated by higher internal extraction control Cq values. Conclusions/Significance Detection of SL-RNA in blood and CSF allows sensitive demonstration of active gambiense HAT infection, even if trypanosomes remain undetectable in blood or lymph. As this condition often occurs in treatment failures, SL-RNA detection in blood and CSF for early detection of relapses after treatment deserves further investigation. Trial registration This study was an integral part of the diagnostic trial "New Diagnostic Tools for Elimination of Sleeping Sickness and Clinical Trials: Early tests of Cure" (DiTECT-HAT-WP4, ClinicalTrials.gov Identifier: NCT03112655). Human African trypanosomiasis is a parasitic infection occurring in sub-Saharan Africa, which is fatal if left untreated. Diagnosis relies on demonstration of trypanosomes, which may occur at such low concentrations that they remain microscopically undetectable. Nucleic acid detection offers an alternative, in particular RNA, which is unstable and a better marker for live organisms than DNA. Trypanosomal SL-RNA detection in blood by reverse transcriptase quantitative PCR has hitherto only been tested twice. Although in cerebrospinal fluid, trypanosome presence indicates brain infection, SL-RNA detection has never been attempted. We evaluated sensitivity of SL-RNA detection in blood and cerebrospinal fluid. For each specimen, 2 controls were included: presence of genomic DNA contamination and efficacy of RNA extraction. Sensitivity of SL-RNA detection in blood was higher than of combined blood and lymph microscopy. In cerebrospinal fluid, SL-RNA and trypanosome detection had similar sensitivity. In a few specimens, traces of DNA were amplified. In some cerebrospinal fluids, some RNA was lost during extraction. Performing both internal controls is crucial, to ensure that negative SL-RNA cerebrospinal fluid findings are not due to a failed extraction and, in particular when testing treated patients, to differentiate live parasite RNA from reminiscent DNA.
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Affiliation(s)
- Ipos Ngay Lukusa
- Department of Parasitology, Institut National de Recherche Biomédicale, Kinshasa, Democratic Republic of the Congo
| | - Nick Van Reet
- Department of Biomedical Sciences, Institute of Tropical Medecine, Antwerp, Belgium
| | - Dieudonné Mumba Ngoyi
- Department of Parasitology, Institut National de Recherche Biomédicale, Kinshasa, Democratic Republic of the Congo
| | - Erick Mwamba Miaka
- Programme National de Lutte contre la Trypanosomiase Humaine Africaine (PNLTHA), Ministry of Health, Kinshasa, Democratic Republic of the Congo
| | - Justin Masumu
- Department of Parasitology, Institut National de Recherche Biomédicale, Kinshasa, Democratic Republic of the Congo
| | - Pati Patient Pyana
- Department of Parasitology, Institut National de Recherche Biomédicale, Kinshasa, Democratic Republic of the Congo
| | - Wilfried Mutombo
- Programme National de Lutte contre la Trypanosomiase Humaine Africaine (PNLTHA), Ministry of Health, Kinshasa, Democratic Republic of the Congo
| | - Digas Ngolo
- Programme National de Lutte contre la Trypanosomiase Humaine Africaine (PNLTHA), Ministry of Health, Kinshasa, Democratic Republic of the Congo
| | - Vincent Kobo
- Programme National de Lutte contre la Trypanosomiase Humaine Africaine (PNLTHA), Ministry of Health, Kinshasa, Democratic Republic of the Congo
| | - Felix Akwaso
- Programme National de Lutte contre la Trypanosomiase Humaine Africaine (PNLTHA), Ministry of Health, Kinshasa, Democratic Republic of the Congo
| | - Médard Ilunga
- Programme National de Lutte contre la Trypanosomiase Humaine Africaine (PNLTHA), Ministry of Health, Kinshasa, Democratic Republic of the Congo
| | - Lewis Kaninda
- Programme National de Lutte contre la Trypanosomiase Humaine Africaine (PNLTHA), Ministry of Health, Kinshasa, Democratic Republic of the Congo
| | - Sylvain Mutanda
- Programme National de Lutte contre la Trypanosomiase Humaine Africaine (PNLTHA), Ministry of Health, Kinshasa, Democratic Republic of the Congo
| | - Dieudonné Mpoyi Muamba
- Programme National de Lutte contre la Trypanosomiase Humaine Africaine (PNLTHA), Ministry of Health, Kinshasa, Democratic Republic of the Congo
| | | | - Antoine Tarral
- Drugs for Neglected Diseases initiative, Geneva, Switzerland
| | - Sandra Rembry
- Drugs for Neglected Diseases initiative, Geneva, Switzerland
| | - Philippe Büscher
- Department of Biomedical Sciences, Institute of Tropical Medecine, Antwerp, Belgium
| | - Veerle Lejon
- Mixed Research Unit 177 Intertryp, Institut de Recherche pour le Développement, Centre de Coopération Internationale en Recherche Agronomique pour le Développement, University of Montpellier, Montpellier, France
- * E-mail:
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Wombou Toukam CM, Solano P, Bengaly Z, Jamonneau V, Bucheton B. Experimental evaluation of xenodiagnosis to detect trypanosomes at low parasitaemia levels in infected hosts. Parasite 2012; 18:295-302. [PMID: 22091459 PMCID: PMC3677595 DOI: 10.1051/parasite/2011184295] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
In Human African Trypanosomosis (HAT) endemic areas, there are a number of subjects that are positive to serological tests but in whom trypanosomes are difficult to detect with the available parasitological tests. In most cases and particularly in West Africa, these subjects remain untreated, thus posing a fundamental problem both at the individual level (because of a possible lethal evolution of the disease) and at the epidemiological level (since they are potential reservoirs of trypanosomes). Xenodiagnosis may constitute an alternative for this type of cases. The objective of this study was to update the use of xenodiagnosis to detect trypanosomes in infected host characterized by low parasitaemia levels. This was carried out experimentally by infecting cattle and pigs with Trypanosoma congolense and T. brucei gambiense respectively, and by feeding tsetse flies (Glossina morsitans submorsitans and G. palpalis gambiensis, from the CIRDES colonies) on these animals at a time when the observed blood parasitaemia were low or undetectable by the classical microscopic parasitological tests used for the monitoring of infected animals. Our results showed that: i) the G. p. gambiensis colony at CIRDES could not be infected with the T. b. gambiense stocks used; ii) midgut infections of G. m. submorsitans were observed with both T. congolense and T. b. gambiense; iii) xenodiagnosis remains positive even at very low blood parasitaemia for both T. congolense and T. b. gambiense; and iv) to implement T. b. gambiense xenodiagnosis, batches of 20 G. m. submorsitans should be dissected two days after the infective meal. These results constitute a first step toward a possible implementation of xenodiagnosis to better characterize the parasitological status of seropositive individuals and the modalities of parasite transmission in HAT foci.
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Affiliation(s)
- C M Wombou Toukam
- Centre international de recherche-développement sur l'élevage en zone subhumide (CIRDES), 01 BP 454 Bobo-Dioulasso 01, Burkina Faso
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Njitchouang GR, Njiokou F, Nana-Djeunga H, Asonganyi T, Fewou-Moundipa P, Cuny G, Simo G. A new transmission risk index for human African trypanosomiasis and its application in the identification of sites of high transmission of sleeping sickness in the Fontem focus of southwest Cameroon. MEDICAL AND VETERINARY ENTOMOLOGY 2011; 25:289-296. [PMID: 21198712 DOI: 10.1111/j.1365-2915.2010.00936.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A new index for the risk for transmission of human African trypanosomiasis was developed from an earlier index by adding terms for the proportion of tsetse infected with Trypanosoma brucei gambiense group 1 and the contribution of animals to tsetse diet. The validity of the new index was then assessed in the Fontem focus of southwest Cameroon. Averages of 0.66 and 4.85 Glossina palpalis palpalis (Diptera: Glossinidae) were caught per trap/day at the end of one rainy season (November) and the start of the next (April), respectively. Of 1596 tsetse flies examined, 4.7% were positive for Trypanosoma brucei s.l. midgut infections and 0.6% for T. b. gambiense group 1. Among 184 bloodmeals identified, 55.1% were from pigs, 25.2% from humans, 17.6% from wild animals and 1.2% from goats. Of the meals taken from humans, 81.5% were taken at sites distant from pigsties. At the end of the rainy season, catches were low and similar between biotopes distant from and close to pigsties, but the risk for transmission was greatest at sites distant from the sties, suggesting that the presence of pigs reduced the risk to humans. At the beginning of the rainy season, catches of tsetse and risk for transmission were greatest close to the sties. In all seasons, there was a strong correlation between the old and new indices, suggesting that both can be used to estimate the level of transmission, but as the new index is the more comprehensive, it may be more accurate.
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Affiliation(s)
- G R Njitchouang
- General Biology Laboratory, Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, Yaoundé, Cameroon.
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