Long-term outcomes of ivermectin-albendazole versus albendazole alone against soil-transmitted helminths: Results from randomized controlled trials in Lao PDR and Pemba Island, Tanzania

Egg excretion patterns of soil-transmitted helminth infections in humans following albendazole-ivermectin and albendazole treatment

BACKGROUND

Control efforts of soil-transmitted helminthiases rely primarily on large scale administration of anthelminthic drugs. The assessment of drug efficacies and understanding of drug behavior is pivotal to the evaluation of treatment successes, both in preventive chemo-therapy programs as well as in research of novel treatment options. The current WHO guidelines recommend an interval of 14-21 days between the treatment and follow-up, yet no in-depth analysis of egg excretion patterns of Trichuris trichiura after treatment has been conducted to date.

METHODS

Within the framework of a multi-country trial to assess the efficacy and safety of albendazole-ivermectin combination therapy vs albendazole monotherapy against T. trichiura infections, we conducted a study collecting daily stool samples over the period of 28 days post-treatment in 87 participants in Pak Khan, Lao PDR. Egg counts were derived by duplicate Kato-Katz on-site for T. trichiura, hookworm and Ascaris lumbricoides and stool sample aliquots were subsequently analyzed by qPCR for the detection of T. trichiura infections. Sensitivity and specificity was calculated for each day separately using data derived by Kato-Katz to determine the optimal timepoint at which to assess drug efficacy.

RESULTS

Egg excretion patterns varied across treatment arms. For T. trichiura, only the albendazole-ivermectin treatment led to a considerable reduction in mean egg counts, whereas both treatments reduced hookworm egg counts and A. lumbricoides were cleared in all participants after day 7. For T. trichiura, we found sensitivity to be highest at days 18 and 22 when using egg counts as outcome and days 19 and 24 when using qPCR. Specificity was high (>0.9) from day 14 onwards. For hookworm, the highest sensitivity and specificity were found at days 17 and 25, respectively.

CONCLUSIONS

Based on our study, the ideal time period to assess drug efficacy for soil-transmitted helminth infections would be between day 18 and 24. The current WHO recommendation of 14 to 21 days is likely to yield acceptable outcome measures for soil-transmitted helminth infections.

TRIAL REGISTRATION

NCT03527732.

Progress towards the implementation of control programmes for strongyloidiasis in endemic areas: estimation of number of adults in need of ivermectin for strongyloidiasis

The World Health Organization has started a process to issue guidelines for the control of strongyloidiasis. The guidelines might recommend to implement preventive chemotherapy (PC) at community level (i.e. to all individuals above 5 years of age), over a defined prevalence threshold. We previously estimated the number of school-age children (SAC) who would need PC. Here we estimate the number of people above 15 years of age who might be included in PC for strongyloidiasis. Based on previous Strongyloides prevalence estimates and on countries' age distribution, we retrieved the number of adults in need of PC. We then subtracted the number of people already involved in ivermectin mass distribution for the elimination of onchocerciasis and lymphatic filariasis and people living in countries where Loa loa is endemic. The number of adults to be involved in PC was estimated at 905.4 (95% confidence interval (CI): 520.6-1177.2), 660.2 (95% CI: 512.7-1214.9), and 512.1 (95% CI: 276-719.4) million people, when the strongyloidiasis prevalence threshold for implementing PC was set to 10%, 15% and 20%, respectively. Estimates at country level are also provided.These estimates might help endemic countries wishing to implement PC for strongyloidiasis to allocate resources to include adults in addition to SAC in control programmes. This article is part of the Theo Murphy meeting issue 'Strongyloides: omics to worm-free populations'.

The impact of ivermectin, diethylcarbamazine citrate, and albendazole mass drug administration on the prevalence of scabies and soil-transmitted helminths in school-aged children in three municipalities in Timor-Leste: a before-after assessment

BACKGROUND

Integrated programmes that use combination mass drug administration (MDA) might improve control of multiple neglected tropical diseases simultaneously. We investigated the impact of Timor-Leste's national ivermectin, diethylcarbamazine citrate, and albendazole MDA, for lymphatic filariasis elimination and soil-transmitted helminth (STH) control, on scabies, impetigo, and STH infections.

METHODS

We did a before-after study in six primary schools across three municipalities in Timor-Leste (urban [Dili], semi-urban [Ermera], and rural [Manufahi]) before (April 23 to May 11, 2019) and 18 months after (Nov 9 to Nov 27, 2020) MDA delivery between May 17 and June 1, 2019. Study participants included schoolchildren, as well as infants, children, and adolescents who were incidentally present at school on study days. All schoolchildren whose parents provided consent were eligible to participate in the study. Infants, children, and adolescents younger than 19 years who were not enrolled in the school but were incidentally present at schools on study days were also eligible to participate if their parents consented. Ivermectin, diethylcarbamazine citrate, and albendazole MDA was implemented nationally, with single doses of oral ivermectin (200 μg/kg), diethylcarbamazine citrate (6 mg/kg), and albendazole (400 mg) administered by the Ministry of Health. Scabies and impetigo were assessed by clinical skin examinations, and STHs using quantitative PCR. The primary (cluster-level) analysis adjusted for clustering while the secondary (individual-level) analysis adjusted for sex, age, and clustering. The primary outcomes of the study were prevalence ratios for scabies, impetigo, and STHs (Trichuris trichiura, Ascaris lumbricoides, Necator americanus, and moderate-to-heavy A lumbricoides infections) between baseline and 18 months from the cluster-level analysis.

FINDINGS

At baseline, 1043 (87·7%) of 1190 children registered for the study underwent clinical assessment for scabies and impetigo. The mean age of those who completed skin examinations was 9·4 years (SD 2·4) and 514 (53·8%) of 956 were female (87 participants with missing sex data were excluded from this percentage calculation). Stool samples were received for 541 (45·5%) of 1190 children. The mean age of those for whom stool samples were received was 9·8 years (SD 2·2) and 300 (55·5%) were female. At baseline, 348 (33·4%) of 1043 participants had scabies, and 18 months after MDA, 133 (11·1%) of 1196 participants had scabies (prevalence ratio 0·38, 95% CI 0·18-0·88; p=0·020) in the cluster-level analysis. At baseline, 130 (12·5%) of 1043 participants had impetigo, compared with 27 (2·3%) of 1196 participants at follow-up (prevalence ratio 0·14, 95% CI 0·07-0·27; p<0·0001). There was a significant reduction in T trichiura prevalence from baseline (26 [4·8%] of 541 participants) to 18-month follow-up (four [0·6%] of 623 participants; prevalence ratio 0·16, 95% CI 0·04-0·66; p<0·0001). In the individual-level analysis, moderate-to-heavy A lumbricoides infections reduced from 54 (10·0%; 95% CI 0·7-19·6) of 541 participants to 28 (4·5%, 1·2-8·4) of 623 participants (relative reduction 53·6%; 95% CI 9·1-98·1; p=0·018).

INTERPRETATION

Ivermectin, diethylcarbamazine citrate, and albendazole MDA was associated with substantial reductions in prevalence of scabies, impetigo, and T trichiura, and of moderate-to-heavy intensity A lumbricoides infections. Combination MDA could be used to support integrated control programmes to target multiple NTDs.

FUNDING

National Health and Medical Research Council of Australia and the Department of Foreign Affairs and Trade Indo-Pacific Centre for Health Security.

TRANSLATION

For the Tetum translation of the abstract see Supplementary Materials section.

Emodepside for Trichuris trichiura and Hookworm Infection

BACKGROUND

Current treatments for soil-transmitted helminth infections in humans have low efficacy against Trichuris trichiura. Emodepside - a drug in veterinary use and under development for the treatment of onchocerciasis in humans - is a leading therapeutic candidate for soil-transmitted helminth infection.

METHODS

We conducted two phase 2a, dose-ranging, randomized, controlled trials to evaluate the efficacy and safety of emodepside against T. trichiura and hookworm infections. We randomly assigned, in equal numbers, adults 18 to 45 years of age in whom T. trichiura or hookworm eggs had been detected in stool samples to receive emodepside, at a single oral dose of 5, 10, 15, 20, 25, or 30 mg; albendazole, at a single oral dose of 400 mg; or placebo. The primary outcome was the percentage of participants who were cured of T. trichiura or hookworm infection (the cure rate) with emodepside 14 to 21 days after treatment, determined with the use of the Kato-Katz thick-smear technique. Safety was assessed 3, 24, and 48 hours after the receipt of treatment or placebo.

RESULTS

A total of 266 persons were enrolled in the T. trichiura trial and 176 in the hookworm trial. The predicted cure rate against T. trichiura in the 5-mg emodepside group (85% [95% confidence interval {CI}, 69 to 93]; 25 of 30 participants) was higher than the predicted cure rate in the placebo group (10% [95% CI, 3 to 26]; 3 of 31 participants) and the observed cure rate in the albendazole group (17% [95% CI, 6 to 35]; 5 of 30 participants). A dose-dependent relationship was shown in participants with hookworm: the observed cure rate was 32% (95% CI, 13 to 57; 6 of 19 participants) in the 5-mg emodepside group and 95% (95% CI, 74 to 99.9; 18 of 19 participants) in the 30-mg emodepside group; the observed cure rates were 14% (95% CI, 3 to 36; 3 of 21 participants) in the placebo group and 70% (95% CI, 46 to 88; 14 of 20 participants) in the albendazole group. In the emodepside groups, headache, blurred vision, and dizziness were the most commonly reported adverse events 3 and 24 hours after treatment; the incidence of events generally increased in a dose-dependent fashion. Most adverse events were mild in severity and were self-limited; there were few moderate and no serious adverse events.

CONCLUSIONS

Emodepside showed activity against T. trichiura and hookworm infections. (Funded by the European Research Council; ClinicalTrials.gov number, NCT05017194.).

Ivermectin and moxidectin against soil-transmitted helminth infections

Ivermectin and moxidectin, two macrocyclic lactones, are potent antiparasitic drugs currently registered and mainly used against filarial diseases; however, their potential value for improved soil-transmitted helminth (STH) control has been acknowledged. This review provides insights on recent studies evaluating the efficacy of ivermectin and moxidectin as single or coadministered therapy against human soil-transmitted helminthiases (including Strongyloides stercoralis infections) and on pharmacokinetic/pharmacodynamic parameters measured in treated populations. Furthermore, we discuss current gaps for research, highlight advantages - but also existing challenges - for uptake of ivermectin and/or moxidectin treatment schemes into routine STH control in endemic countries.

Efficacy and safety of moxidectin and albendazole compared with ivermectin and albendazole coadministration in adolescents infected with Trichuris trichiura in Tanzania: an open-label, non-inferiority, randomised, controlled, phase 2/3 trial

BACKGROUND

Control efforts against soil-transmitted helminths focus on preventive chemotherapy with albendazole and mebendazole, however these drugs yield unsatisfactory results against Trichuris trichiura infections. We aimed to assess the efficacy and safety of moxidectin and albendazole compared with ivermectin and albendazole against T trichiura in adolescents living on Pemba Island, Tanzania.

METHODS

This open-label, non-inferiority, randomised, controlled, phase 2/3 trial was done in four secondary schools (Kilindi, Kwale, Ndagoni [Chake Chake District], and Kiuyu [Wete District]) on Pemba Island, Tanzania. Adolescents aged 12-19 years who tested positive for T trichiura in at least two of four Kato-Katz slides with a mean infection intensity of 48 eggs per gram (EPG) of stool or higher were considered for inclusion. Participants were randomly assigned (21:21:2:2:8) to five treatment groups (8 mg moxidectin and 400 mg albendazole [group 1], 200 μg/kg ivermectin and 400 mg albendazole [group 2], 400 mg albendazole [group 3], 200 μg/kg ivermectin [group 4], or 8 mg moxidectin [group 5]) using a computer-generated randomisation code, stratified by baseline T trichiura infection intensity. Study site investigators and participants were not masked to study treatment; however, allocation was concealed to participants. The primary outcome was egg reduction rate (ERR) of T trichiura 14-21 days after treatment in the available case population. Moxidectin and albendazole was considered non-inferior to ivermectin and albendazole (control group) when the lower limit of the two-sided 95% CI of the difference was higher than the non-inferiority margin of -2 percentage points. This study is registered with ClinicalTrials.gov, NCT04700423.

FINDINGS

Between March 1 and April 30, 2021, 771 participants were assessed for eligibility. 221 (29%) of 771 participants were ineligible and a further 14 (2%) were excluded. 207 (39%) of 536 participants were randomly assigned to moxidectin and albendazole, 211 (39%) to ivermectin and albendazole, 19 (4%) to albendazole, 19 (4%) to ivermectin, and 80 (15%) to moxidectin. Primary outcome data were available for all 536 participants. The geometric mean ERR of T trichiura after 14-21 days was 96·8% (95% CI 95·8 to 97·6) with moxidectin and albendazole and 99·0% (98·7 to 99·3) with ivermectin and albendazole (difference of -2·2 percentage points [-4·2 to -1·4]). No serious adverse events were reported during the study. The most reported adverse events were headache (160 [34%] of 465), abdominal pain (78 [17%]), itching (44 [9%]), and dizziness (26 [6%]).

INTERPRETATION

Our findings show inferiority of moxidectin and albendazole to ivermectin and albendazole against T trichiura. However, given the high efficacy, moxidectin coadministration might complement treatment progammes, particularly in areas in which ivermectin is not available FUNDING: Bill and Melinda Gates Foundation, reference number OPP1153928.

Impact of preventive chemotherapy on transmission of soil-transmitted helminth infections in Pemba Island, United Republic of Tanzania, 1994–2021

Soil-transmitted helminth (STH) infections cause significant morbidity in children and women of reproductive age. The World Health Organization (WHO) recommends preventive chemotherapy (PC) of at-risk populations with anthelminthics to control these infections. Historically, STH are very intensively transmitted in Pemba Island (Zanzibar). A survey conducted in 1994 in 12 schools estimated a STH prevalence near to 100%. This extremely high prevalence induced the introduction of PC in the island; initially, however, PC was not regularly administered because of difficulties linked to drug procurement. A second STH survey, conducted in 2011, in 24 schools estimated a prevalence of STH of 89%; after this survey, PC was regularly administered until 2018. We conducted a survey in 2021 using the same method as that used in 2011. The prevalence of STH was evaluated at 80% (95% CI 78.1–81.5) and most of the STH cases were due to Trichuris trichiura. More than 32% (95% CI 30.3–34.0) of the children investigated had infections of moderate or heavy intensity. PC has been conducted for over 25 years in Pemba Island. However, despite its beneficial impact, both the prevalence and the intensity of STH infections remain high, and the intervention has been insufficient in controlling STH morbidity. This is probably due to a combination of irregular PC, climatic conditions favourable to STH transmission, the low sensitivity of T. trichiura to benzimidazoles, high population density and poor sanitation. Improvement of sanitation coverage remains a key measure to permanently reduce the prevalence and intensity of STH. Possible changes to the present PC approaches to better control STH in Pemba would be (i) to assure high coverage in all schools, (ii) to use mebendazole instead of albendazole given its better activity on T. trichiura and (iii) to use a combination of ivermectin and mebendazole to further increase anthelminthic efficacy on T. trichiura.

A survey conducted in 1994 in school aged children showed that soil-transmitted helminth were very intensively transmitted in Pemba Island (Zanzibar) with prevalence near to 100%. Between 1994 and 2011 several rounds of administration of anthelminthic were organized and a second survey was conducted in 2011 showing a decrease of prevalence and intensity of infection.

The present paper reports the results of a third survey conducted in 2021 showing a further decline of the prevalence and a persistence of T. trichiura as the more prevalent parasite (in 1994 hookworms were the most transmitted STH). The interventions conducted until now where not sufficient to eliminate the morbidity caused by these parasites and it is suggested to include ivermectin in the anthelminthic distributed periodically.

Resistance to single dose albendazole and reinfection with intestinal helminths among children ages 2 to 11 years from the Peruvian Amazon region: a study protocol

BACKGROUND

Deworming programs aimed at reducing morbidity and mortality from geohelminth infections are common in many countries where these infections are endemic, but data demonstrating increasing levels of resistance to albendazole and mebendazole are causes for concern. Studies to evaluate the clinical efficacy of deworming programs are critical to maintain high infection control goals.

METHODS

We propose to assess the clinical efficacy of Peruvian national guidelines for deworming programs in a prospective observational study conducted in the Amazon River basin area near Iquitos, Peru. Major outcomes to be evaluated include (1) albendazole resistance of intestinal helminths (trichuriasis, ascariasis, hookworm), and (2) frequency of reinfection with intestinal helminths 4 months after treatment with albendazole. Children ages 2-11 years from the Belén District of Iquitos will be identified based on a community census. Following parental informed consent, demographic data, weight, and height will be recorded and a stool specimen for parasitological exam by direct observation and Kato-Katz concentration method, and helminthic egg counts will be collected prior to administration of albendazole, following Peruvian national guidelines. Follow-up stool specimens examined in the same manner will be collected at 20 days, 90 days, and 100 days following initial administration of albendazole, and based on parasites found repeat treatment will be administered in accordance with national guidelines. Real-time multiplex qPCR will be performed on helminth positive samples collected prior to initial deworming and on helminth-positive specimens detected on day 15-20. A total sample size of 380 participants was calculated based on total population in the target group and prevalence estimates of helminth infections and clinical resistance based on recent data.

DISCUSSION

Data from observational clinical efficacy studies are important to guide geohelminth infection control programs. Trial registration https://www.researchregistry.com/ . Identification number: researchregistry7736; Registered retrospectively March 13, 2022; https://www.researchregistry.com/browse-the-registry#home/registrationdetails/622e024cf06132001e3327bf/.

Different gut microbial communities correlate with efficacy of albendazole-ivermectin against soil-transmitted helminthiases

Soil-transmitted helminth infections represent a large burden with over a quarter of the world’s population at risk. Low cure rates are observed with standard of care (albendazole); therefore, a more effective combination therapy (albendazole and ivermectin) is being investigated but showed variable treatment efficacies without evidence of intrinsic parasite resistance. Here, we analyzed the microbiome of Trichuris trichiura and hookworm-infected patients and found an association of different enterotypes with treatment efficacy. 80 T. trichiura-infected patients with hookworm co-infections from Pak-Khan, Laos, received either albendazole (n = 41) or albendazole and ivermectin combination therapy (n = 39). Pre-/post-treatment stool samples were collected to monitor treatment efficacy and microbial communities were profiled using 16S rRNA gene sequencing, qPCR, and shotgun sequencing. We identified three bacterial enterotypes and show that pre-treatment enterotype is associated with efficacy of the combination treatment for both T. trichiura (CR_ET1 = 5.8%; CR_ET2 = 16.6%; CR_ET3 = 68.8%) and hookworm (CR_ET1 = 31.3%; CR_ET2 = 16.6%; CR_ET3 = 78.6%). This study shows that pre-treatment enterotype enables predicting treatment outcome of combination therapy for T. trichiura and hookworm infections.

Trial registration: ClinicalTrials.gov, NCT03527732. Registered 17 May 2018, https://clinicaltrials.gov/ct2/show/NCT03527732.

Little is known about the cause of treatment failure of soil-transmitted helminth infections. Here, the authors show that pre-treatment gut microbial community composition enables predicting treatment outcome for Trichuris trichiura and hookworm infections.

Towards global control of parasitic diseases in the Covid-19 era: One Health and the future of multisectoral global health governance

Human parasitic infections—including malaria, and many neglected tropical diseases (NTDs)—have long represented a Gordian knot in global public health: ancient, persistent, and exceedingly difficult to control. With the coronavirus disease (Covid-19) pandemic substantially interrupting control programmes worldwide, there are now mounting fears that decades of progress in controlling global parasitic infections will be undone. With Covid-19 moreover exposing deep vulnerabilities in the global health system, the current moment presents a watershed opportunity to plan future efforts to reduce the global morbidity and mortality associated with human parasitic infections. In this chapter, we first provide a brief epidemiologic overview of the progress that has been made towards the control of parasitic diseases between 1990 and 2019, contrasting these fragile gains with the anticipated losses as a result of Covid-19. We then argue that the complementary aspirations of the United Nations Sustainable Development Goals (SDGs) and the World Health Organization (WHO)’s 2030 targets for parasitic disease control may be achieved by aligning programme objectives within the One Health paradigm, recognizing the interdependence between humans, animals, and the environment. In so doing, we note that while the WHO remains the preeminent international institution to address some of these transdisciplinary concerns, its underlying challenges with funding, authority, and capacity are likely to reverberate if left unaddressed. To this end, we conclude by reimagining how models of multisectoral global health governance—combining the WHO's normative and technical leadership with greater support in allied policy-making areas—can help sustain future malaria and NTD elimination efforts.