1
|
Hedtke SM, Kuesel AC, Crawford KE, Graves PM, Boussinesq M, Lau CL, Boakye DA, Grant WN. Genomic Epidemiology in Filarial Nematodes: Transforming the Basis for Elimination Program Decisions. Front Genet 2020; 10:1282. [PMID: 31998356 PMCID: PMC6964045 DOI: 10.3389/fgene.2019.01282] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 11/21/2019] [Indexed: 11/25/2022] Open
Abstract
Onchocerciasis and lymphatic filariasis are targeted for elimination, primarily using mass drug administration at the country and community levels. Elimination of transmission is the onchocerciasis target and global elimination as a public health problem is the end point for lymphatic filariasis. Where program duration, treatment coverage, and compliance are sufficiently high, elimination is achievable for both parasites within defined geographic areas. However, transmission has re-emerged after apparent elimination in some areas, and in others has continued despite years of mass drug treatment. A critical question is whether this re-emergence and/or persistence of transmission is due to persistence of local parasites-i.e., the result of insufficient duration or drug coverage, poor parasite response to the drugs, or inadequate methods of assessment and/or criteria for determining when to stop treatment-or due to re-introduction of parasites via human or vector movement from another endemic area. We review recent genetics-based research exploring these questions in Onchocerca volvulus, the filarial nematode that causes onchocerciasis, and Wuchereria bancrofti, the major pathogen for lymphatic filariasis. We focus in particular on the combination of genomic epidemiology and genome-wide associations to delineate transmission zones and distinguish between local and introduced parasites as the source of resurgence or continuing transmission, and to identify genetic markers associated with parasite response to chemotherapy. Our ultimate goal is to assist elimination efforts by developing easy-to-use tools that incorporate genetic information about transmission and drug response for more effective mass drug distribution, surveillance strategies, and decisions on when to stop interventions to improve sustainability of elimination.
Collapse
Affiliation(s)
- Shannon M. Hedtke
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, VIC, Australia
| | - Annette C. Kuesel
- Unicef/UNDP/World Bank/World Health Organization Special Programme for Research and Training in Tropical Diseases (TDR), World Health Organization, Geneva, Switzerland
| | - Katie E. Crawford
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, VIC, Australia
| | - Patricia M. Graves
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Cairns, QLD, Australia
| | - Michel Boussinesq
- Unité Mixte Internationale 233 "TransVIHMI", Institut de Recherche pour le Développement (IRD), INSERM U1175, University of Montpellier, Montpellier, France
| | - Colleen L. Lau
- Department of Global Health, Research School of Population Health, Australian National University, Acton, ACT, Australia
| | - Daniel A. Boakye
- Parasitology Department, Noguchi Memorial Institute for Medical Research, Accra, Ghana
| | - Warwick N. Grant
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, VIC, Australia
| |
Collapse
|
2
|
Mary KA, Krishnamoorthy K, Hoti SL. Scope of detectability of circulating antigens of human lymphatic filarial parasite Wuchereria bancrofti with smaller amount of serum by Og4C3 assay: its application in lymphatic filariasis elimination programme. J Parasit Dis 2016; 40:1622-1626. [PMID: 27876997 PMCID: PMC5118297 DOI: 10.1007/s12639-015-0671-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 02/26/2015] [Indexed: 11/25/2022] Open
Abstract
Filarial antigen detection is an appropriate epidemiological indicator for mapping lymphatic filariasis and impact evaluation of filariasis elimination programme in view of low sensitivity of parasite detection. Monoclonal antibody-based Og4C3 immunological test requires 100 µl serum, which is difficult to collect by finger prick method during community based surveys. Hence, we tested lesser volume of serum compared to standard volume of 100 µl to compare its sensitivity and specificity in detecting the circulating filarial antigens. Blood samples were collected from individuals who tested positive [with titer groups 4 (border line positives), 6 (medium positives), and 8 (high positives)] and negative (titre group 3) for Og4C3 assay. Different volumes of serum samples were used to make-up required volume (100 µl) with appropriate dilutions and subjected to Og4C3 assay. The results showed that known negative samples tested negative at all the serum volumes tested. All positives (titer groups 6 and 8) showed positivity at all reduced volumes of serum sample. However one of the medium positive sample showed negative reaction in 5 µl volume of serum and two of the border line positives showed negative at all the serum volume tested. The results thus showed as less as 15 µl serum is adequate for use in Og4C3 assay. So the test can be performed without losing its sensitivity even with 5 µl serum samples at high titre of antigen (titre group 8) and 15 µl for other groups and this method has scope in programme evaluation.
Collapse
Affiliation(s)
- K. Athisaya Mary
- Unit of Microbiology and Immunology, Vector Control Research Centre (Indian Council of Medical Research and Department of Health Research), Indira Nagar, Puducherry, 605 006 India
| | - K. Krishnamoorthy
- Unit of Epidemiology and Operational Research, Vector Control Research Centre (Indian Council of Medical Research and Department of Health Research), Indira Nagar, Puducherry, 605 006 India
| | - S. L. Hoti
- Unit of Microbiology and Immunology, Vector Control Research Centre (Indian Council of Medical Research and Department of Health Research), Indira Nagar, Puducherry, 605 006 India
| |
Collapse
|
3
|
Ramasamy D, Laxmanappa HS, Sharma R, Das MK. Influence of anti-filarial chemotherapy strategies on the genetic structure of Wuchereria bancrofti populations. Mem Inst Oswaldo Cruz 2011; 106:240-7. [PMID: 21537687 DOI: 10.1590/s0074-02762011000200020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Accepted: 12/16/2010] [Indexed: 11/21/2022] Open
Abstract
Lymphatic filarial (LF) parasites have been under anti-filarial drug pressure for more than half a century. Currently, annual mass drug administration (MDA) of diethylcarbamazine (DEC) or ivermectin in combination with albendazole (ALB) have been used globally to eliminate LF. Long-term chemotherapies exert significant pressure on the genetic structure of parasitic populations. We investigated the genetic variation among 210 Wuchereria bancrofti populations that were under three different chemotherapy strategies, namely MDA with DEC alone (group I, n = 74), MDA with DEC and ALB (group II, n = 60) and selective therapy (ST) with DEC (group III, n = 34) to understand the impact of these three drug regimens on the parasite genetic structure. Randomly amplified polymorphic DNA profiles were generated for the three groups of parasite populations; the gene diversity, gene flow and genetic distance values were determined and phylogenetic trees were constructed. Analysis of these parameters indicated that parasite populations under ST with a standard dose of DEC (group III) were genetically more diverse (0.2660) than parasite populations under MDA with DEC alone (group I, H = 0.2197) or with DEC + ALB (group II, H = 0.2317). These results indicate that the MDA may reduce the genetic diversity of W. bancrofti populations when compared to the genetic diversity of parasite populations under ST.
Collapse
Affiliation(s)
- Dhamodharan Ramasamy
- Vector Control Research Centre, Indian Council of Medical Research, Puducherry, India
| | | | | | | |
Collapse
|
4
|
Molecular differentiation of nocturnally periodic and diurnally sub-periodic Wuchereria bancrofti by Randomly Amplified Polymorphic DNA (RAPD). World J Microbiol Biotechnol 2010; 27:1525-30. [PMID: 25187153 DOI: 10.1007/s11274-010-0601-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Accepted: 10/22/2010] [Indexed: 10/18/2022]
Abstract
Wuchereria bancrofti, a nematode parasite, is responsible for causing 90% of lymphatic filariasis infection in the world. In India, W. bancrofti exists in two physiological forms, nocturnally periodic in the main land and diurnally sub-periodic in Car Nicobar group of islands. Differentiation of these two parasitic forms by conventional microscopic methods difficult requiring good skill and hence tedious. Therefore, we developed a simple and rapid Random Amplified Polymorphic DNA (RAPD) assay to differentiate these parasitic forms. Also, the phylogenetic relationship between periodic and sub-periodic W. bancrofti and also Brugia malayi populations was analyzed using RAPD profile generated. Distinct RAPD profiles were observed among the three parasites with the formation of three distinct clusters in the phylogenetic tree. Substantial genetic diversity (Nei's genetic diversity H) was observed among periodic (H = 0.0577) and sub-periodic (H = 0.1415) W. bancrofti populations.
Collapse
|