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PLoS Neglected Tropical Diseases Dec 2022Mansonella perstans is among the most neglected of the neglected tropical diseases and is believed to cause more human infections than any other filarial pathogen in...
Targeting a highly repetitive genomic sequence for sensitive and specific molecular detection of the filarial parasite Mansonella perstans from human blood and mosquitoes.
BACKGROUND
Mansonella perstans is among the most neglected of the neglected tropical diseases and is believed to cause more human infections than any other filarial pathogen in Africa. Based largely upon assumptions of limited infection-associated morbidity, this pathogen remains understudied, and many basic questions pertaining to its pathogenicity, distribution, prevalence, and vector-host relationships remain unanswered. However, in recent years, mounting evidence of the potential for increased Mansonella infection-associated disease has sparked a renewal in research interest. This, in turn, has produced a need for improved diagnostics, capable of providing more accurate pictures of infection prevalence, pathogen distribution, and vector-host interactions.
METHODOLOGY/PRINCIPAL FINDINGS
Utilizing a previously described pipeline for the discovery of optimal molecular diagnostic targets, we identified a repetitive DNA sequence, and developed a corresponding assay, which allows for the sensitive and species-specific identification of M. perstans in human blood samples. Testing also demonstrated the ability to utilize this assay for the detection of M. perstans in field-collected mosquito samples. When testing both sample types, our repeat-targeting index assay outperformed a ribosomal sequence-targeting reference assay, facilitating the identification of additional M. perstans-positive samples falsely characterized as "negative" using the less sensitive detection method.
CONCLUSIONS/SIGNIFICANCE
Through the development of an assay based upon the systematic identification of an optimal DNA target sequence, our novel diagnostic assay will provide programmatic efforts with a sensitive and specific testing platform that is capable of accurately mapping M. perstans infection and determining prevalence. Furthermore, with the added ability to identify the presence of M. perstans in mosquito samples, this assay will help to define our knowledge of the relationships that exist between this pathogen and the various geographically relevant mosquito species, which have been surmised to represent potential secondary vectors under certain conditions. Detection of M. perstans in mosquitoes will also demonstrate proof-of-concept for the mosquito-based monitoring of filarial pathogens not vectored primarily by mosquitoes, an approach expanding opportunities for integrated surveillance.
Topics: Animals; Humans; Mansonella; Parasites; Culicidae; Mosquito Vectors; Genomics; Mansonelliasis
PubMed: 36580452
DOI: 10.1371/journal.pntd.0010615 -
Vaccine Dec 2010Some vaccines show poor efficacy in tropical countries. Within a birth cohort in Uganda, we investigated factors that might influence responses to BCG and tetanus...
Some vaccines show poor efficacy in tropical countries. Within a birth cohort in Uganda, we investigated factors that might influence responses to BCG and tetanus immunisation. Whole blood assay responses to crude culture filtrate proteins of Mycobacterium tuberculosis (cCFP)) and tetanus toxoid (TT) were examined among 1506 and 1433 one-year-olds, respectively. Maternal Mansonella perstans infection was associated with higher interleukin (IL)-10 responses to both immunogens but no reduction in gamma interferon (IFN-γ), IL-5 and IL-13 responses; other maternal helminth infections showed little effect. Tetanus immunisation during pregnancy was associated with higher infant responses to TT; maternal BCG scar (from past immunisation) with lower infant IL-5 and IL-13 responses to cCFP. IFN-γ, IL-5 and IL-13 to TT were reduced in HIV-exposed-uninfected infants; infant malaria and HIV were associated with lower IFN-γ, IL-5 and IL-13 responses to both immunogens. We conclude that maternal helminth infections are unlikely to explain poor vaccine efficacy in the tropics. Effects of maternal immunisation on infant responses to vaccines should be explored. Prevention of infant malaria and HIV could contribute to effectiveness of immunisation programmes.
Topics: Adult; Antibodies, Bacterial; BCG Vaccine; Cohort Studies; Cytokines; Female; HIV Infections; Humans; Infant; Infant, Newborn; Lymphocytes; Malaria; Male; Mansonelliasis; Mycobacterium tuberculosis; Pregnancy; Tetanus Toxoid; Uganda
PubMed: 21040693
DOI: 10.1016/j.vaccine.2010.10.047 -
The American Journal of Tropical... Sep 2015Large parts of African and American countries are colonized by Mansonella, a very common but poorly described filarial nematode. Bloodsucking flies of the genus...
Large parts of African and American countries are colonized by Mansonella, a very common but poorly described filarial nematode. Bloodsucking flies of the genus Culicoides are suspected to be the vector of Mansonella perstans, but no study in Senegal has confirmed that Culicoides can transmit the parasite. Designed specific real-time quantitative polymerase chain reaction (qPCR) can be used to identify microfilaria in stained blood smears. This study was performed in July and December 2010 in the southeastern Senegal, which is known to be endemic for M. perstans. We analyzed 297 blood smears from febrile and afebrile resident people by qPCR. The global prevalence of M. perstans was approximately 14.5% in both febrile and afebrile individuals. The age group of > 30 years had the highest prevalence (22.0%). No Culicoides among 1,159 studied specimens was positive for M. perstans and its vector in Senegal still requires identification.
Topics: Adolescent; Adult; Age Factors; Animals; Ceratopogonidae; Child; Child, Preschool; Female; Humans; Infant; Insect Vectors; Male; Mansonella; Mansonelliasis; Middle Aged; Prevalence; Real-Time Polymerase Chain Reaction; Rural Population; Senegal; Young Adult
PubMed: 26078318
DOI: 10.4269/ajtmh.15-0051 -
The American Journal of Tropical... Jul 2019Treating is challenged by the low efficacy of registered antihelminthics. endobacteria provide an alternative treatment target because depletion results in... (Randomized Controlled Trial)
Randomized Controlled Trial
Treating is challenged by the low efficacy of registered antihelminthics. endobacteria provide an alternative treatment target because depletion results in amicrofilaremia in filarial infections with and infections. This open-label, randomized study sought to confirm that i) are present in in Ghana and ii) doxycycline treatment will deplete and cause a slow, sustained decline in microfilariae (MF). Two hundred and two Ghanaians with infection were randomized into early (immediate) and delayed (6 months deferred) treatment groups, given doxycycline 200 mg/day for 6 weeks, and monitored for MF and levels at baseline, 4, 12, and 24 months after the study onset (= time of randomization and start of treatment for the early group). Per protocol analysis revealed that the median MF/mL in the early group declined from 138 at baseline to 64 at month 4 and further to 0 at month 12. In the delayed group, MF load did not change from a baseline median of 97 to 102 at month 4 but declined to 42 at month 12, that is, 6 months after receiving treatment, trailing the early group as expected. By month 24, both treatment groups had reached a median MF level of 0. After treatment, were depleted from MF by ≥ 1-log drop compared with baseline levels. We conclude that in Ghana harbor that are effectively depleted by doxycycline with subsequent reduction in MF loads, most likely because of interruption of fertility of adult worms.
Topics: Adolescent; Adult; Animals; Anti-Bacterial Agents; Child; Doxycycline; Female; Ghana; Humans; Male; Mansonella; Mansonelliasis; Middle Aged; Young Adult
PubMed: 31162017
DOI: 10.4269/ajtmh.18-0491 -
African Health Sciences Jun 2013Nodding Syndrome is a seizure disorder of children in Mundri County, Western Equatoria, South Sudan. The disorder is reported to be spreading in South Sudan and northern...
BACKGROUND
Nodding Syndrome is a seizure disorder of children in Mundri County, Western Equatoria, South Sudan. The disorder is reported to be spreading in South Sudan and northern Uganda.
OBJECTIVE
To describe environmental, nutritional, infectious, and other factors that existed before and during the de novo 1991 appearance and subsequent increase in cases through 2001.
METHODS
Household surveys, informant interviews, and case-control studies conducted in Lui town and Amadi village in 2001-2002 were supplemented in 2012 by informant interviews in Lui and Juba, South Sudan.
RESULTS
Nodding Syndrome was associated with Onchocerca volvulus and Mansonella perstans infections, with food use of a variety of sorghum (serena) introduced as part of an emergency relief program, and was inversely associated with a history of measles infection. There was no evidence to suggest exposure to a manmade neurotoxic pollutant or chemical agent, other than chemically dressed seed intended for planting but used for food. Food use of cyanogenic plants was documented, and exposure to fungal contaminants could not be excluded.
CONCLUSION
Nodding Syndrome in South Sudan has an unknown etiology. Further research is recommended on the association of Nodding Syndrome with onchocerciasis/mansonelliasis and neurotoxins in plant materials used for food.
Topics: Animals; Communicable Diseases; Confidence Intervals; Environmental Exposure; Food Contamination; Health Surveys; Humans; Nodding Syndrome; Odds Ratio; Qualitative Research; Sudan; Zoonoses
PubMed: 24235915
DOI: 10.4314/ahs.v13i2.2 -
CD39 and immune regulation in a chronic helminth infection: The puzzling case of Mansonella ozzardi.PLoS Neglected Tropical Diseases Mar 2018Chronic helminth infections typically induce an immunoregulatory environment, with markedly reduced immune responses to both parasite-specific and unrelated bystander...
BACKGROUND
Chronic helminth infections typically induce an immunoregulatory environment, with markedly reduced immune responses to both parasite-specific and unrelated bystander antigens. Here we tested whether these changes are also observed in human infections with Mansonella ozzardi, a neglected filarial nematode widely distributed across Latin America.
METHODS
CD4+ T cell populations from microfilaremic (Fil+) and uninfected (Fil-) inhabitants in M. ozzardi-endemic riverine communities in Brazil were characterized by flow cytometry analysis. Plasma concentrations of a wide range of cytokines and chemokines were measured. We examined whether M. ozzardi infection is associated with suppressed in vitro lymphoproliferative and inflammatory cytokine responses upon stimulation with filarial antigen, unrelated antigens or mitogens.
PRINCIPAL FINDINGS/CONCLUSIONS
Fil+ subjects had lower plasma levels of selected inflammatory cytokines, such as TNF-α, IL-8, and IL-6, than their Fil- counterparts. However, we found no evidence for attenuated T-cell responses to filarial antigens or co-endemic pathogens, such as malaria parasites and Toxoplasma gondii. CD4+ T cells expressing CD39, an ectonucleosidase involved in the generation of the anti-inflammatory molecule adenosine, were increased in frequency in Fil+ subjects, compared to uninfected controls. Significantly, such an expansion was directly proportional to microfilarial loads. Surprisingly, CD39 blocking with a neutralizing antibody suppressed antigen-driven lymphoproliferation in vitro, while decreasing inflammatory cytokine responses, in Fil+ and Fil- individuals. These findings suggest that circulating CD4+ CD39+ T cells comprise subsets with both regulatory and stimulatory roles that contribute to the immune homeostasis in chronic M. ozzardi infection.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Animals; Antigens, Helminth; Apyrase; Brazil; CD4-Positive T-Lymphocytes; Child; Cytokines; Female; Humans; Immunoglobulin G; Male; Mansonella; Mansonelliasis; Microfilariae; Middle Aged; Young Adult
PubMed: 29505582
DOI: 10.1371/journal.pntd.0006327 -
Parasites & Vectors Nov 2017Approximately 114 million people are infected with Mansonella perstans in large proportions of Africa. In contrast to other filariae that infect humans, M....
BACKGROUND
Approximately 114 million people are infected with Mansonella perstans in large proportions of Africa. In contrast to other filariae that infect humans, M. perstans-infected individuals show no distinct pathology or specific clinical picture, indicating a well-tuned adaptation to the host. In addition, since M. perstans adult worms reside in serous cavities which are difficult to access, research has been hindered and there is a paucity of knowledge about the biology of M. perstans, especially the development of the different life stages as well as M. perstans-driven immune responses. Thus in this study, an in vitro culture system was developed which allows an in-depth analysis of M. perstans.
RESULTS
Culicoides species were caught in Ediki (Kumba), Southwest Region within Cameroon following a blood meal on a microfilaremic donor that had 1500 microfilariae/ml of peripheral blood and kept in captivity for 12 days at 23 °C. In a pilot experiment, 15 infective larvae were obtained from the midges and co-cultured with a confluent monolayer of monkey kidney epithelial cells (LLC-MK2) in DMEM medium supplemented with 10% FBS for up to 77 days. The resulting survival rates of 33% revealed that the cell-conditioned medium was suitable for long-term maintenance of M. perstans worms. To confirm these preliminary observations, 249 infective larvae were cultured for 50 days and their development was monitored daily and microscopically graded for motility. In total, 170 (68.3%) filariae survived and 124 (49.8%) larvae moulted between days 21-30 to become L5 stage larvae which were motile and showed continuous vigorous movement.
CONCLUSION
We have established an in vitro culture system for the generation and long-term maintenance of viable M. perstans worms. This technique will be an important tool to study parasite biology and development, the role in host immunity, and might be helpful to discover novel treatment strategies against this filariae.
Topics: Animals; Cameroon; Cell Line; Ceratopogonidae; Coculture Techniques; Culture Media; Epithelial Cells; Haplorhini; Humans; Kidney; Larva; Mansonella; Mansonelliasis; Microfilariae; Time Factors
PubMed: 29126431
DOI: 10.1186/s13071-017-2515-8 -
Cytokine Apr 2018Mansonellosis is an endemic disease in the South and Central America. In Brazil, one of the etiological agents is Mansonella ozzardi. This filarial infection is yet...
Mansonellosis is an endemic disease in the South and Central America. In Brazil, one of the etiological agents is Mansonella ozzardi. This filarial infection is yet poorly understood, with a controversial morbity, presenting since a oligosymptoms, malaria-like signs or without complaint in humans. The knowledge of the human immune response to microfilariae infection is limited mainly by different evolutionary cycles of the parasite in the host. In addition, the prevalence of this filarial parasite infection is high in several regions of Amazonas State. A cross-sectional study was conducted in an endemic area for microfilariae of M. ozzardi (MF) infection in the Amazonas State, Brazil. Proinflammatory and regulatory cytokines (IL-2, IL-4, IL-6, IL-10, TNF, IFN-gamma, and IL-17A) were measured in cryopreserved serum using the Cytometric Bead Array techniques (CBA) in 54 patients diagnosed with M. ozzardi infection and 55 individuals without the infection were included in the study (Controls). The IL-4, IL-6 and IL-10 level increased in infected patients with MF infection, while IL-17A increased in control only. When we compared controls to patients with high or low parasite load, the increased level of IL-6 and IL-10 were maintained. IL-6 contributes to the proinflammatory activity and IL-10 modulates Th1, Th2 and Th17 immune response. Furthermore, IL-4 was detected as a marker in the MF infection and MF patients with low parasite load, indicating the action of the Th2 cell response. The complex network of cytokines acting during M. ozzardi infection depends on a fine balance to determine a host protective effect or filarial persistence. Therefore, these results suggest that the immune response in MF infection is modulated by IL-6/IL-10 axis.
Topics: Adult; Animals; Biomarkers; Brazil; Cytokines; Female; Humans; Interleukin-10; Interleukin-4; Interleukin-6; Male; Mansonella; Mansonelliasis; Middle Aged
PubMed: 29032984
DOI: 10.1016/j.cyto.2017.09.033 -
PLoS Neglected Tropical Diseases 2015Like other tropical African countries, Gabon is afflicted by many parasitic diseases, including filariases such as loiasis and mansonellosis. This study aimed to assess...
BACKGROUND
Like other tropical African countries, Gabon is afflicted by many parasitic diseases, including filariases such as loiasis and mansonellosis. This study aimed to assess the prevalence of these two filarial diseases in febrile and afebrile children using quantitative real-time PCR and standard PCR assays coupled with sequencing.
METHODOLOGY/PRINCIPAL FINDINGS
DNA from blood specimens of 1,418 Gabonese children (1,258 febrile and 160 afebrile) were analyzed. Overall, filarial DNA was detected in 95 (6.7%) children, including 67 positive for M. perstans (4.7%), which was the most common. M. perstans was detected in 61/1,258 febrile children (4.8%) and 6/160 afebrile children (3.8%, P = 0.6). Its prevalence increased statistically with age: 3.5%, 7.7% and 10.6% in children aged ≤ 5, 6-10 and 11-15 years, respectively. M. perstans prevalence was significantly higher in Koulamoutou and Lastourville (12% and 10.5%, respectively) than in Franceville and Fougamou (2.6% and 2.4%, respectively). Loa loa was detected in seven febrile children including one co-infection with M. perstans. Finally, 21 filarial DNA positive were negative for M. perstans and Loa loa, but ITS sequencing could be performed for 12 and allowed the identification of a potential new species of Mansonella provisionally called "DEUX". Mansonella sp. "DEUX" was detected only in febrile children.
CONCLUSIONS/SIGNIFICANCE
Further study should be performed to characterize Mansonella sp. "DEUX" and evaluate the clinical significance of mansonellosis in humans.
Topics: Adolescent; Age Factors; Animals; Blood; Child; Child, Preschool; Cluster Analysis; DNA, Helminth; DNA, Ribosomal Spacer; Female; Gabon; Humans; Infant; Loa; Loiasis; Male; Mansonella; Mansonelliasis; Molecular Sequence Data; Phylogeny; Polymerase Chain Reaction; Prevalence; Sequence Analysis, DNA; Topography, Medical
PubMed: 26484866
DOI: 10.1371/journal.pntd.0004155 -
Blood Transfusion = Trasfusione Del... Apr 2010
Topics: Animals; Blood; Blood Donors; Chad; Endemic Diseases; Eosinophilia; Humans; Infant; Mansonella; Mansonelliasis; Mass Screening; Microfilariae; Parasitemia; Transfusion Reaction; Travel
PubMed: 20383308
DOI: 10.2450/2009.0140-09