Mapping lymphatic filariasis in Loa loa endemic health districts naïve for ivermectin mass administration and situated in the forested zone of Cameroon

Abstract Background The control of lymphatic filariasis (LF) caused by Wuchereria bancrofti in the Central African Region has been hampered by the presence of Loa loa due to severe adverse events that arise in the treatment with ivermectin. The immunochromatographic test (ICT) cards used for mapping LF demonstrated cross-reactivity with L. loa and posed the problem of delineating the LF map. To verify LF endemicity in forest areas of Cameroon where mass drug administration (MDA) has not been ongoing, we used the recently developed strategy that combined serology, microscopy and molecular techniques. Methods This study was carried out in 124 communities in 31 health districts (HDs) where L. loa is present. At least 125 persons per site were screened. Diurnal blood samples were investigated for circulating filarial antigen (CFA) by FTS and for L. loa microfilariae (mf) using TBF. FTS positive individuals were further subjected to night blood collection for detecting W . bancrofti . qPCR was used to detect DNA of the parasites. Results Overall, 14,446 individuals took part in this study, 233 participants tested positive with FTS in 29 HDs, with positivity rates ranging from 0.0% to 8.2%. No W . bancrofti mf was found in the night blood of any individuals but L. loa mf were found in both day and night blood of participants who were FTS positive. Also, qPCR revealed that no W. bancrofti but L.loa DNA was found with dry bloodspot. Positive FTS results were strongly associated with high L. loa mf load. Similarly, a strong positive association was observed between FTS positivity and L loa prevalence. Conclusions Using a combination of parasitological and molecular tools, we were unable to find evidence of W. bancrofti presence in the 31 HDs, but L. loa instead. Therefore, LF is not endemic and LF MDA is not required in these districts.

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Mapping lymphatic filariasis in Loa loa endemic health districts naïve for ivermectin mass administration and situated in the forested zone of Cameroon.

10.21203/rs.2.22134/v2 ◽

2020 ◽

Author(s):

Andrew A Beng ◽

Mathias E Esum ◽

Kebede Deribe ◽

Abdel J Njouendou ◽

Patrick WC Ndongmo ◽

...

Keyword(s):

Lymphatic Filariasis ◽

Positive Association ◽

Wuchereria Bancrofti ◽

Cross Reactivity ◽

Molecular Techniques ◽

Blood Collection ◽

Loa Loa ◽

African Region ◽

Strong Positive Association ◽

Health Districts

Abstract Background The control of lymphatic filariasis (LF) caused by Wuchereria bancrofti in the Central African Region has been hampered by the presence of Loa loa due to severe adverse events that arise in the treatment with ivermectin. The immunochromatographic test (ICT) cards used for mapping LF demonstrated cross-reactivity with L. loa and posed the problem of delineating the LF map. To verify LF endemicity in forest areas of Cameroon where mass drug administration (MDA) has not been ongoing, we used the recently developed strategy that combined serology, microscopy and molecular techniques. Methods This study was carried out in 124 communities in 31 health districts (HDs) where L. loa is present. At least 125 persons per site were screened. Diurnal blood samples were investigated for circulating filarial antigen (CFA) by FTS and for L. loa microfilariae (mf) using TBF. FTS positive individuals were further subjected to night blood collection for detecting W . bancrofti . qPCR was used to detect DNA of the parasites. Results Overall, 14,446 individuals took part in this study, 233 participants tested positive with FTS in 29 HDs, with positivity rates ranging from 0.0% to 8.2%. No W . bancrofti mf was found in the night blood of any individuals but L. loa mf were found in both day and night blood of participants who were FTS positive. Also, qPCR revealed that no W. bancrofti but L.loa DNA was found with dry bloodspot. Positive FTS results were strongly associated with high L. loa mf load. Similarly, a strong positive association was observed between FTS positivity and L loa prevalence. Conclusions Using a combination of parasitological and molecular tools, we were unable to find evidence of W. bancrofti presence in the 31 HDs, but L. loa instead. Therefore, LF is not endemic and LF MDA is not required in these districts.

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Lymphatic filariasis and loa loa

Principles of Medicine in Africa ◽

10.1017/cbo9780511751660.049 ◽

2013 ◽

pp. 453-456

Author(s):

Camilla Rothe ◽

Christopher J. M. Whitty ◽

Eldryd Parry

Keyword(s):

Lymphatic Filariasis ◽

Loa Loa

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Semiannual Treatment of Albendazole Alone is Efficacious for Treatment of Lymphatic Filariasis: A Randomized Open-label Trial in Cote d'Ivoire

Clinical Infectious Diseases ◽

10.1093/cid/ciab194 ◽

2021 ◽

Author(s):

Allassane F Ouattara ◽

Catherine M Bjerum ◽

Méité Aboulaye ◽

Olivier Kouadio ◽

Vanga K Marius ◽

...

Keyword(s):

Lymphatic Filariasis ◽

Primary Outcome ◽

Central Africa ◽

Wuchereria Bancrofti ◽

Bancroftian Filariasis ◽

Loa Loa ◽

Open Label ◽

Treatment Groups ◽

Open Label Trial ◽

To Receive

Abstract Background Ivermectin (IVM) plus albendazole (ALB), or IA, is widely used in mass drug administration (MDA) programs that aim to eliminate lymphatic filariasis (LF) in Africa. However, IVM can cause severe adverse events in persons with heavy Loa loa infections that are common in Central Africa. ALB is safe in loiasis, but more information is needed on its efficacy for LF. This study compared the efficacy and safety of three years of semiannual treatment with ALB to annual IA in persons with bancroftian filariasis. Methods Adults with Wuchereria bancrofti microfilaremia (Mf) were randomized to receive either three annual doses of IA (N=52), six semiannual doses of ALB 400mg (N=45), or six semiannual doses of ALB 800mg (N=47). The primary outcome amicrofilaremia at 36 months. Findings IA was more effective for completely clearing Mf than ALB 400mg or ALB 800mg (79%, CI 67-91; vs. 48%, CI 32-66 and 57%, CI 41-73, respectively). Mean % reductions in Mf counts at 36 months relative to baseline tended to be greater after IA (98%, CI 88-100) than after ALB 400mg (88%, CI 78-98) and ALB 800mg (89%, CI 79-99) (P=0.07 and P=0.06, respectively). Adult worm nest numbers (assessed by ultrasound) were reduced in all treatment groups. Treatments were well tolerated. Interpretation Repeated semiannual treatment with ALB is macrofilaricidal for W. bancrofti and leads to sustained reductions in Mf counts. This is a safe and effective regimen that could be used as MDA to eliminate LF in areas ivermectin cannot be used.

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Loa loa vectors Chrysops spp.: perspectives on research, distribution, bionomics, and implications for elimination of lymphatic filariasis and onchocerciasis

Parasites & Vectors ◽

10.1186/s13071-017-2103-y ◽

2017 ◽

Vol 10 (1) ◽

Cited By ~ 15

Author(s):

Louise Kelly-Hope ◽

Rossely Paulo ◽

Brent Thomas ◽

Miguel Brito ◽

Thomas R. Unnasch ◽

...

Keyword(s):

Lymphatic Filariasis ◽

Loa Loa

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Elimination of lymphatic filariasis in Loa loa areas

The Lancet Infectious Diseases ◽

10.1016/s1473-3099(17)30163-9 ◽

2017 ◽

Vol 17 (7) ◽

pp. 683-684

Author(s):

Antonio Montresor ◽

Jonathan D King

Keyword(s):

Lymphatic Filariasis ◽

Loa Loa

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Malaria and Lymphatic Filariasis Co-Transmission in Endemic Health Districts in Burkina Faso

Advances in Entomology ◽

10.4236/ae.2021.94014 ◽

2021 ◽

Vol 09 (04) ◽

pp. 155-175

Author(s):

Sanata Coulibaly ◽

Simon Péguédwindé Sawadogo ◽

Aristide Sawdetuo Hien ◽

Achille Sindimbasba Nikièma ◽

Ibrahim Sangaré ◽

...

Keyword(s):

Burkina Faso ◽

Lymphatic Filariasis ◽

Health Districts

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A Step Toward Eradication of Human Filariases in Areas Where Loa Is Endemic

mBio ◽

10.1128/mbio.00456-16 ◽

2016 ◽

Vol 7 (2) ◽

Cited By ~ 9

Author(s):

Timothy G. Geary

Keyword(s):

Adverse Events ◽

Drug Treatment ◽

Lymphatic Filariasis ◽

Drug Administration ◽

Mass Drug Administration ◽

Diagnostic Method ◽

Parasitic Infections ◽

Loa Loa ◽

Risk Threshold ◽

Rapid Diagnostic Method

ABSTRACT Mass drug administration (MDA) programs have achieved remarkable success in limiting the pathology and transmission of the human parasitic infections onchocerciasis and lymphatic filariasis. The full implementation of MDA campaigns for filariasis elimination has been stymied by the unacceptable incidence of severe adverse events observed following drug treatment of a subset of individuals who harbor high loads of Loa loa microfilaria. Extending MDA strategies to regions where loiasis is coendemic could be done confidently if a simple, inexpensive, and rapid diagnostic method was available that could accurately identify individuals who have L. loa microfilarial loads above the risk threshold and could thus be excluded from treatment. A recent paper in mBio reports the discovery of an antigen unique to L. loa microfilaria that can be detected in blood and urine and may form the basis for such an assay. Further work will reveal whether this discovery will smooth the path to achieve filariasis eradication.

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Nematodes (roundworms)

10.1093/med/9780198737773.003.0014 ◽

2017 ◽

Author(s):

Philippa C. Matthews

Keyword(s):

Lymphatic Filariasis ◽

Onchocerca Volvulus ◽

River Blindness ◽

Loa Loa ◽

Filarial Infection ◽

Guinea Worm ◽

Treatment And Prevention ◽

Clinical Syndromes

This chapter consists of short notes, diagrams, maps, and tables to summarize human nematode (‘roundworm’) infections, starting with a classification of relevant organisms. The chapter then goes on to cover Ascaris, Trichinella, Enterobius (‘pin worm’), Trichuris (‘whip worm’), Necator and Ancylostoma (‘hook worms’), and Strongyloides (‘thread worm’). The chapter concludes with a section dedicated to filarial infection, including lymphatic filariasis, Loa Loa (‘eye worm’), Onchocerca volvulus (‘river blindness’), and Dracunculus (‘Guinea worm’). For ease of reference, each topic is broken down into sections, including classification, epidemiology, microbiology, pathophysiology, clinical syndromes, diagnosis, treatment and prevention.

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