scholarly journals Feasibility of onchocerciasis elimination using a “test-and-not-treat” strategy in Loa loa co-endemic areas

2020 ◽  
Author(s):  
David J Blok ◽  
Joseph Kamgno ◽  
Sebastien D Pion ◽  
Hugues C Nana-Djeunga ◽  
Yannick Niamsi-Emalio ◽  
...  
Keyword(s):  
Adverse Events ◽  
Drug Administration ◽  
Mass Drug Administration ◽  
Treatment Duration ◽  
Loa Loa ◽  
Serious Adverse Events ◽  
Endemic Areas ◽  
The Individual ◽  
The Impact ◽  
Main Strategy

Abstract Background Mass drug administration (MDA) with ivermectin is the main strategy for onchocerciasis elimination. Ivermectin is generally safe but associated with serious adverse events in individuals with high Loa loa microfilarial densities (MFD). Therefore, ivermectin MDA is not recommended in areas where onchocerciasis is hypo-endemic and L. loa is co-endemic. To eliminate onchocerciasis in those areas, a test-and-not-treat (TaNT) strategy has been proposed. We investigated whether onchocerciasis elimination can be achieved using TaNT and the required duration. Methods We used the individual-based model ONCHOSIM to predict the impact of TaNT on onchocerciasis microfilarial (mf) prevalence. We simulated pre-control mf prevalence levels from 2-40%. The impact of TaNT was simulated under varying levels of participation, systematic non-participation and exclusion from ivermectin due to high L. loa MFD. For each scenario, we assessed the time to elimination, defined as bringing onchocerciasis mf prevalence below 1.4%. Results In areas with 30-40% pre-control mf prevalence, the model predicted that it would take between 14 and 16 years to bring the mf prevalence below 1.4% using conventional MDA, assuming 65% participation. TaNT would increase the time to elimination by up to 1.5 years, depending on the level of systematic non-participation and the exclusion rate. At lower exclusion rates (≤2.5%), the delay would be less than six months. Conclusions Our model predicts that onchocerciasis can be eliminated using TaNT in L. loa co-endemic areas. The required treatment duration using TaNT would be only slightly longer than in areas with conventional MDA, provided that participation is good.

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

mBio ◽  
2016 ◽  
Vol 7 (2) ◽  
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.

scholarly journals Projected Number of People With Onchocerciasis–Loiasis Coinfection in Africa, 1995 to 2025

2019 ◽  
Vol 70 (11) ◽  
pp. 2281-2289 ◽  
Author(s):  
Natalie V S Vinkeles Melchers ◽  
Luc E Coffeng ◽  
Michel Boussinesq ◽  
Belén Pedrique ◽  
Sébastien D S Pion ◽  
...  
Keyword(s):  
At Risk ◽  
Adverse Events ◽  
Control Strategies ◽  
Central Africa ◽  
Ivermectin Treatment ◽  
Loa Loa ◽  
Serious Adverse Events ◽  
West And Central Africa ◽  
And Control ◽  
The Impact

Abstract Background Onchocerciasis elimination through mass drug administration (MDA) is hampered by coendemicity of Loa loa, as people with high L. loa microfilariae (mf) density can develop serious adverse events (SAEs) after ivermectin treatment. We assessed the geographical overlap of onchocerciasis and loiasis prevalence and estimated the number of coinfected individuals at risk of post-ivermectin SAEs in West and Central Africa from 1995 to 2025. Methods Focusing on regions with suspected loiasis transmission in 14 countries, we overlaid precontrol maps of loiasis and onchocerciasis prevalence to calculate precontrol prevalence of coinfection by 5 km2 × 5 km2 pixel, distinguishing different categories of L. loa mf intensity. Using statistical and mathematical models, we predicted prevalence of both infections and coinfection for 2015 and 2025, accounting for the impact of MDA with ivermectin. Results The number of people infected with onchocerciasis was predicted to decline from almost 19 million in 1995 to 4 million in 2025. Of these, 137 000 people were estimated to also have L. loa hypermicrofilaremia (≥20 000 L. loa mf/mL) in 1995, declining to 31 000 in 2025. In 2025, 92.8% of coinfected cases with loiasis hypermicrofilaremia are predicted to live in hypoendemic areas currently not targeted for MDA. Conclusions Loiasis coinfection is a major concern for onchocerciasis elimination in Africa. We predict that under current strategies, at least 31 000 coinfected people still require treatment for onchocerciasis in 2025 while being at risk of SAEs, justifying continued efforts in research and development for safer drugs and control strategies.

scholarly journals A strong effect of individual compliance with mass drug administration for lymphatic filariasis on sustained clearance of soil-transmitted helminth infections

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Jérémy T. Campillo ◽  
Naomi P. Awaca-Uvon ◽  
Jean-Paul Tambwe ◽  
Godefroy Kuyangisa-Simuna ◽  
Johnny Vlaminck ◽  
...  
Keyword(s):  
Lymphatic Filariasis ◽  
Drug Administration ◽  
Mass Drug Administration ◽  
Democratic Republic Of Congo ◽  
Central Africa ◽  
Survival Models ◽  
Republic Of Congo ◽  
The Individual ◽  
Time Required ◽  
The Impact

Abstract Background The impact of semiannual mass drug administration (MDA) with albendazole (ALB; 400 mg) alone on lymphatic filariasis (LF) and soil-transmitted helminth (STH) infections was assessed during two trials conducted from 2012 to 2018 in the Republic of Congo and the Democratic Republic of Congo. The collected data were analyzed to evaluate the effect of compliance with ALB treatment on STH infections. Methods STH infections were diagnosed with duplicate Kato-Katz thick smears and the results are reported as eggs per gram of stool. All subjects with at least two STH infection assessments were included in the analyses. We used parametric survival models to assess the influence of compliance with ALB treatment on the probability of (i) achieving sustained clearance of an STH infection, and (ii) acquiring an STH infection during the follow-up. Results Out of 2658 subjects included in the trials, data on 202 participants (701 person-years; PY) with hookworm infection, 211 (651 PY) with Ascaris lumbricoides infection and 270 (1013 PY) with Trichuris trichiura infection were available to calculate the probability of achieving sustained clearance of infection. The effect of ALB was dose related for all three STH. For hookworm, the time required for sustained clearance was longer (4.3 years, P < 0.001) for participants who took zero doses per year and shorter (3.4 years, P = 0.112) for participants who took two doses per year compared to those who took one dose per year (3.7 years). For Ascaris, the time required to obtain sustained clearance followed the same pattern: 6.1 years (P < 0.001) and 3.2 years (P = 0.004) vs 3.6 years for, zero, two and one dose per year, respectively. For Trichuris, less time was required for sustained clearance (4.2 years, P < 0.001) for fully compliant participants, i.e. those who took two doses per year, than for those who only took one dose per year (5.0 years). ALB was more effective in achieving sustained clearance of STH infection in subjects with light baseline infection intensities compared to those with higher egg counts. Conclusion Our results illustrate the importance of MDA compliance at the level of the individual with respect to the STH benefit provided by semiannual ALB MDA, which is used for the elimination of LF in Central Africa. Graphic abstract

scholarly journals The impact of mass drug administration expansion to low onchocerciasis prevalence settings in case of connected villages

2021 ◽  
Vol 15 (5) ◽  
pp. e0009011
Author(s):  
Anneke S. de Vos ◽  
Wilma A. Stolk ◽  
Luc E. Coffeng ◽  
Sake J. de Vlas
Keyword(s):  
Intermediate Host ◽  
Drug Administration ◽  
Mass Drug Administration ◽  
Human Populations ◽  
Individual Based Model ◽  
Low Prevalence ◽  
The Impact ◽  
Local Transmission

Background The existence of locations with low but stable onchocerciasis prevalence is not well understood. An often suggested yet poorly investigated explanation is that the infection spills over from neighbouring locations with higher infection densities. Methodology We adapted the stochastic individual based model ONCHOSIM to enable the simulation of multiple villages, with separate blackfly (intermediate host) and human populations, which are connected through the regular movement of the villagers and/or the flies. With this model we explore the impact of the type, direction and degree of connectedness, and of the impact of localized or full-area mass drug administration (MDA) over a range of connected village settings. Principal findings In settings with annual fly biting rates (ABR) below the threshold needed for stable local transmission, persistence of onchocerciasis prevalence can well be explained by regular human traffic and/or fly movement from locations with higher ABR. Elimination of onchocerciasis will then theoretically be reached by only implementing MDA in the higher prevalence area, although lingering infection in the low prevalence location can trigger resurgence of transmission in the total region when MDA is stopped too soon. Expanding MDA implementation to the lower ABR location can therefore shorten the duration of MDA needed. For example, when prevalence spill-over is due to human traffic, and both locations have about equal populations, then the MDA duration can be shortened by up to three years. If the lower ABR location has twice as many inhabitants, the reduction can even be up to six years, but if spill-over is due to fly movement, the expected reduction is less than a year. Conclusions/Significance Although MDA implementation might not always be necessary in locations with stable low onchocerciasis prevalence, in many circumstances it is recommended to accelerate achieving elimination in the wider area.

scholarly journals Can direct smear results that are routinely collected at health centre level be used for monitoring the impact of mass drug administration with praziquantel on schistosomiasis in Burundi? A preliminary assessment.

2020 ◽  
Author(s):  
Paul BIZIMANA ◽  
Katja POLMAN ◽  
Giuseppina ORTU ◽  
Meryam KRIT ◽  
Frédéric NSABIYUMVA ◽  
...  
Keyword(s):  
Drug Administration ◽  
Mass Drug Administration ◽  
Health Centre ◽  
Health Information System ◽  
Routine Data ◽  
Direct Smear ◽  
Incidence Data ◽  
Intestinal Schistosomiasis ◽  
The Impact ◽  
Health Centre Level

Abstract Background : Intestinal schistosomiasis is still a public health problem in Burundi. Since 2008, annual mass drug administration with praziquantel have been rolled out in 11 endemic districts. The national programme relies on school-based surveys with Kato-Katz to monitor the impact of mass drug administration. We explored whether routine data on intestinal schistosomiasis as determined by direct fecal smears at health centre level could be used. Methods : From the Burundian National Health Information System, we collected routine incidence data on intestinal schistosomiasis as determined by direct smear examination in all 45 sanitary districts between 2011 and 2015. A temporal trends analysis was performed using a mixed negative binomial regression. Sanitary districts with mass drug administration campaigns with praziquantel (n=11) were compared with those without (n=34). In addition, prevalence data on intestinal schistosomiasis based on Kato-Katz results from a school-based national mapping in 2014 were compared with the incidence data in health centres based on direct smear results, in the same 45 sanitary districts. Findings : In the 11 sanitary districts applying mass drug administration with praziquantel, the incidence rate decreased significantly for the years 2014 (β 2014 =-0.826, p=0.010) and 2015 (β 2015 =-1.294, p<0.001) and for the five-year period (β=-0.286, p<0.001), whereas in the 34 districts where mass drug administration was not delivered, there was no significant decrease over time (β=-0.087, p=0.219). In most of the 45 sanitary districts, the low prevalences based on Kato-Katz in schoolchildren were confirmed by low incidence rates based on direct smear in the health centres. Conclusions : National Health Information System surveillance data, based on routinely collected direct smear results at health centre level, may be able to monitor the impact of mass drug administration with praziquantel on intestinal schistosomiasis in Burundi. Control and elimination of intestinal schistosomiasis call for integration of adequate diagnosis and treatment into routine activities of primary health care facilities, as recommended by the World Health Organization since more than 20 years. When moving towards elimination, more sensitive tests, such as the Point-of-care Circulating Cathodic Antigen assay are desirable. Keywords : Direct smear, Health centre, Mass drug administration, Monitoring, Praziquantel, Routine data, Schistosomiasis, Burundi

EVALUATION OF LYMPHATIC FILARIASIS AFTER TWO ROUNDS OF MASS DRUG ADMINISTRATION IN LAU LOCAL GOVERNMENT AREA OF TARABA STATE NIGERIA

2021 ◽  
Vol 4 (4) ◽  
pp. 513-519
Author(s):  
D. E. Akafyi ◽  
I. S. Ndams ◽  
S. A. Luka ◽  
F. S. Ojeleye ◽  
S. O. Elkanah ◽  
...  
Keyword(s):  
Local Government ◽  
Drug Administration ◽  
Mass Drug Administration ◽  
Clinical Manifestations ◽  
Wuchereria Bancrofti ◽  
Local Government Area ◽  
Filarial Antigen ◽  
Physical Examinations ◽  
The Impact ◽  
Card Test

This study was undertaken to evaluate the effects of Mass Drug Administration (MDA) on Wuchereria bancrofti (microfilariae) after two rounds of combined Ivermectin and Albendazole distribution. A total of 221 participants were recruited in three communities in Lau Local Government Area of Taraba State by convenience sampling method. Questionnaires and physical examinations were used to assess clinical manifestations associated with the infection. Blood samples were collected by finger prick method and stained with Giemsa stain for examination to establish the presence of W. bancrofti while immunochromatographic card test was performed to determine the presence of filarial antigen in serum. Previous data were used to determine the pre-drug prevalence of the parasite. The results showed that the drug did not significantly reduce the clinical manifestations reported among the patients. The microfilariae prevalence and microfilaria mean density after two rounds of drug administration was 19.5% and 1.49%, while the pre- MDA prevalence and microfilaria mean density was 27.8% and 2.44% respectively. There was a statistically significant decrease of microfilaria prevalence (P<0.05) after two rounds of MDA. There was no significant effect of MDA by age, sex and occupation-related microfilariae prevalence in the study area.  In conclusion, the study reveals that microfilaria prevalence and load decreased after two rounds of MDA of combined Ivermectin and Albendazole distribution amongst the studied populations. Routine evaluation of the MDA is required to assess the impact of the drug for the eventual elimination of the infection.

scholarly journals Optimising systemic insecticide use to improve malaria control

2019 ◽  
Vol 4 (6) ◽  
pp. e001776 ◽  
Author(s):  
Hannah R Meredith ◽  
Luis Furuya-Kanamori ◽  
Laith Yakob
Keyword(s):  
Vector Control ◽  
Malaria Transmission ◽  
Drug Administration ◽  
Mass Drug Administration ◽  
Companion Animals ◽  
Malaria Vectors ◽  
Systemic Insecticide ◽  
Blood Concentrations ◽  
Systemic Insecticides ◽  
The Impact

BackgroundLong-lasting insecticidal nets and indoor residual sprays have significantly reduced the burden of malaria. However, several hurdles remain before elimination can be achieved: mosquito vectors have developed resistance to public health insecticides, including pyrethroids, and have altered their biting behaviour to avoid these indoor control tools. Systemic insecticides, drugs applied directly to blood hosts to kill mosquitoes that take a blood meal, offer a promising vector control option. To date, most studies focus on repurposing ivermectin, a drug used extensively to treat river blindness. There is concern that overdependence on a single drug will inevitably repeat past experiences with the rapid spread of pyrethroid resistance in malaria vectors. Diversifying the arsenal of systemic insecticides used for mass drug administration would improve this strategy’s sustainability.MethodsHere, a review was conducted to identify systemic insecticide candidates and consolidate their pharmacokinetic/pharmacodynamic properties. The impact of alternative integrated vector control options and different dosing regimens on malaria transmission reduction are illustrated through mathematical model simulation.ResultsThe review identified drugs from four classes commonly used in livestock and companion animals: avermectins, milbemycins, isoxazolines and spinosyns. Simulations predicted that isoxazolines and spinosyns are promising candidates for mass drug administration, as they were predicted to need less frequent application than avermectins and milbemycins to maintain mosquitocidal blood concentrations.ConclusionsThese findings will provide a guide for investigating and applying different systemic insecticides to achieve more effective and sustainable control of malaria transmission.

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