The Death to Onchocerciasis and Lymphatic Filariasis (DOLF) project conducts clinical and translational research to accelerate the global elimination of lymphatic filariasis (LF) and onchocerciasis (river blindness). Research needs were identified during several meetings of experts and helped study design. Over the last 15 years the project has conducted mass drug administration (MDA) studies and clinical trials with outstanding research teams in 11 countries that have led to many important discoveries. For example, DOLF studies showed that annual MDA was as effective as semiannual MDA for LF elimination and that semiannual MDA with albendazole alone can eliminate LF in areas where ivermectin cannot be safely used. Multiple studies showed that a single dose of the triple-drug combination ivermectin plus diethylcarbamazine and albendazole (IDA) was well tolerated and more effective than previously recommended treatments for LF. Results of these studies led the World Health Organization (WHO) to endorse IDA for LF elimination programs in countries without coendemic onchocerciasis or loiasis. More recently, we have shown that single-dose treatment with moxidectin plus albendazole is superior to the ivermectin plus albendazole regimen currently recommended for LF elimination in Africa. Safety and efficacy studies of combination treatments for onchocerciasis have shown that IDA is more effective against adult Onchocerca volvulus worms than ivermectin plus albendazole, although the effect was modest. We are currently testing the macrofilaricidal efficacy of other drug combinations and treatment schedules. DOLF researchers have also conducted important studies that are not clinical trials. For example, we discovered that some people with high Loa loa microfilaria (Mf, first-stage larvae) densities have cross-reactive filarial antigen tests. DOLF has also addressed the issue of MDA compliance, because improved treatments cannot be effective if people do not swallow the tablets. We highlight here some of DOLF's important discoveries that support the control and elimination of neglected tropical diseases caused by helminths.

BACKGROUND:The COVID-19 pandemic has greatly affected nursing home residents (NHRs), a vulnerable group with high rates of illness and death. While vaccination is essential for reducing infections and severe outcomes in the short term, it is important to understand how long antibody levels and neutralizing activity last. This understanding will help us create effective public health strategies for the long term. According to current CDC guidelines, individuals over 65 should receive a booster dose six months after their previous vaccination. METHODS:This observational retrospective cohort study analyzed post-vaccination serum from samples with up to 400 days of follow-up from 697 NHRs and 127 healthcare workers (HCWs) across Northeast Ohio and Rhode Island. Analyses were conducted to model decay rates of neutralizing and binding antibody titers and the impact of previous exposures to SARS-CoV-2 on these decay rates. RESULTS:Results indicate that NHRs show Wuhan and Omicron BA.4/5 neutralizing and binding antibody titers diminish significantly from 2 weeks to 12 months post-vaccination. NHRs with prior infection show higher peak antibody titers and slower decay than those naive to infection. Antibody levels after vaccination for infection-naive NHR lagged HCW and NHR with prior infection, but then decayed at a similar rate. CONCLUSION:The immunologic findings in this cohort of NHR align with the existing real-world clinical effectiveness data in older individuals and support the CDC recommendation of a bi-annual vaccination to reduce severe COVID-19 outcomes in persons age 65 and older.

West New Britain province (WNBP), Papua New Guinea, is the first to combine ivermectin, diethylcarbamazine, albendazole (IDA), and azithromycin for mass drug administration (MDA). We describe the impact of four-drug MDA on lymphatic filariasis (LF), scabies, and yaws through active and passive surveillance. At baseline, 43 villages were surveyed following selection using model-based geostatistics. Repeat surveys were conducted in 10 high burden villages, one year after MDA. Circulating filarial antigen (CFA) and microfilaria (Mf) microscopy detected LF infections; skin examinations identified yaws and scabies. Electronic data from 27 health centers (HCs) compared monthly attendances in the six months before/after MDA. Pre-MDA, 151/3,552 (4.3%) participants tested CFA-positive, with 49 (1.4%) Mf-positive. Scabies was identified in 489/3,552 (13.8%) and yaws-like lesions in 130/3,552 (3.6%). In the 10 villages surveyed pre- and post-MDA, CFA positivity decreased by 49% (RR 0.51; CI 0.38, 0.70; p<0.0001; 11.5% to 5.9%), Mf prevalence 85% (RR 0.15; CI 0.07, 0.30; p<0.001; 4.7% to 0.9%), scabies 78% (RR 0.22; CI 0.14 - 0.33; p<0.0001; 11.1% to 2.4%) and yaws 31% (RR 0.69; CI 0.41 - 1.14; p=0.15; 3.8% to 2.5%). Mean (SEM) monthly HC attendances for yaws-like lesions decreased from 27.4 ± 0.9 to 15.5 ± 1.6 (p<0.0001) and for other skin diseases from 95.6 ± 3.4 to 72.9 ± 7.7 (p<0.0001), with no significant change in total non-skin disease attendances (728.8 ± 30.9 to 796.8 ± 44.4, p=0.178). MDA with IDA and azithromycin reduced LF and other skin infections burden in WNBP, demonstrating the effectiveness of four-drug MDA and the potential for using active and passive surveillance to monitor impact.

Recurrent infection is more common in Plasmodium vivax malaria. The recurrence of P. vivax can be due to recrudescence, reinfection, or relapse. To characterize the genetic signature of P. vivax genetic diversity and multiplicity of infection (MOI) were assessed using merozoite surface protein 1 gene (pvmsp1). A total of 370 blood samples were collected from 215 individuals visiting health facilities within Arjo-Didessa sugarcane plantations and it's surrounding of Oromia, southwestern Ethiopia. All samples were subjected to amplicon deep sequencing of the pvmsp1 gene. High population genetic diversity was observed-generating 67 unique haplotypes, haplotype diversity (Hd = 0.799), nucleotide diversity (ℼ = 0.044), and expected heterozygosity (HE) = 0.826. However, low MOI = 1.4 and 34.6% polyclonal infections. Of the 215 participant, 82 patients experienced one to five recurrent infections. In paired analysis of primary and recurrent episodes, high genetic homology (81.3%) was observed, with 55.6% of the homologous pairs sharing identical alleles. The high genetic diversity at population and low diversity at individual level likely driven by migrant workers introducing diverse parasite genotypes into a low-transmission setting. Most of the recurrent infections were relapses, as evidenced by shared alleles. The finding highlights the need for strengthening malaria surveillance and tailored intervention particularly for mobile population.

BACKGROUND:The FDA approved the first monovalent XBB1.5 booster vaccine in September 2023. However, whether this vaccine stimulates mucosal immune responses in the oropharynx, especially neutralizing antibodies, remains understudied. METHODS:We analyzed serum and saliva samples from 28 participants, collected one week before and two to three weeks after the XBB1.5 mRNA vaccination, for neutralizing and binding antibodies to Wuhan and XBB1.5 Spike (S) protein. RESULTS:We observed a 2.9-fold increase in Wuhan and a 5.0-fold rise in XBB1.5 serum neutralization titers after mRNA vaccination, which correlated with increased binding antibody levels against the S protein variants in serum. We also examined saliva to assess oral mucosal immune responses to vaccination. Vaccination caused a 1.7-fold increase in ACE2 neutralization in saliva against XBB1.5 (p < 0.0001) and a 1.4-fold increase against Wuhan (p = 0.03). This rise in neutralizing antibody levels in saliva was not associated with the number and timing of previous COVID-19 infections, vaccination status, vaccine type, age, sex, or increases in S-specific IgG in either saliva or serum. Individuals with the largest increase in XBB1.5 neutralization in saliva tended to show a greater rise in S-specific sIgA levels. Depletion of salivary IgA1 or IgG after vaccination revealed that IgA1 was mainly responsible for the increase in ACE2 blocking activity (average reduction in blocking activity with IgA1 depletion = 68%, range 58-81%) compared to IgG (average reduction = 27%, range 0-71%). CONCLUSIONS:The XBB1.5 monovalent vaccine boosts neutralizing antibody levels in blood and mucous membranes, with the largest increase observed against the XBB1.5 variant. This likely reflects the enhancement of cross-reactive antibodies influenced by prior exposure and hybrid immunity, rather than the production of entirely XBB1.5-specific responses. Improved oral mucosal immune responses may reduce the risk of COVID-19 infection and severe illness.

The SARS-CoV-2 Nucleocapsid (N) protein, long regarded as an internal structural component of the virion, unexpectedly localizes to the plasma membrane of infected cells. Here, we show that N is actively trafficked to the cell surface via a ceramide-dependent unconventional secretory pathway. Live-stained imaging and kinetic analyses revealed that N surface association begins early in infection, before Spike (S) expression and viral release, and persists after enzymatic removal of heparan sulfate. Pharmacological disruption of phosphoinositide or phosphatidylserine interactions had minimal effect, whereas inhibition of neutral sphingomyelinase with GW4869 markedly reduced surface N, identifying a ceramide-regulated route as essential for its export. This mechanism distinguishes N from canonical transmembrane viral proteins and explains how N-specific antibodies mediate potent Fc-effector responses across SARS-CoV-2 variants. Our findings redefine the spatiotemporal dynamics of coronavirus structural proteins and reveal an unanticipated axis of immune visibility within the infected cell.

Nursing home residents (NHRs) remain among the most vulnerable to severe outcomes from SARS-CoV-2 infection. While mRNA-1273 (Spikevax, Moderna) and BNT162b2 (Comirnaty, Pfizer-BioNTech) vaccines are widely used in this population, comparative data on their immunogenicity, particularly after bivalent boosters, remain limited. We conducted a longitudinal immunologic evaluation of U.S. NHRs who received either the mRNA-1273 or BNT162b2 bivalent vaccine. Serum samples were collected 10-30 d post-vaccination. Anti-spike IgG levels were measured using a Luminex bead-based assay, and neutralizing titers were assessed via pseudovirus neutralization. Comparative analyses of the titer distributions were performed using two-sided Wilcoxon rank-sum tests. Both vaccine groups demonstrated strong humoral responses to the ancestral Wuhan strain and Omicron BA.4/5 subvariants. Spike-binding antibody levels and neutralization titers were comparable between the mRNA -1273 and BNT162b2 vaccine formulations. Conclusions: Both mRNA-1273 and BNT162b2 mRNA vaccines elicit similarly robust humoral immunity in NHRs, supporting their interchangeable use in booster strategies. Our findings underscore the importance of timely booster administration over exact product selection in protecting this high-risk, immunosenescent population.

The immune response to COVID-19 vaccines is diminished in older individuals. To understand the underlying immunobiology, we analyzed single-cell RNA-seq data from PBMCs of SARS-CoV-2 naive nursing home residents with varying humoral responses following BNT162b2 vaccination and validated via flow cytometry. Responders (R) (>4500 AU/mL anti-spike titers) showed enrichment for naive B cell (IGHD, BACH2, CD22) and naive CD4 T cell and early T follicular helper (Tfh)-related genes (CCR7, TCF7, LEF1, IL6ST, and TGFBR2). Non-responders (NR) (<20 AU/mL) displayed elevated markers of T cell senescence (KLRG1, CCL4, CCL5, and IL32), immune exhaustion (PD-1), and inflammation (TNF-α, IFN-γ). Flow cytometry revealed reduced CD4 T and B cell frequencies but higher CD8 T and NK cells in NR. Despite reduced B cell frequency, NR upregulated plasma B cell genes (PRDM1, XPB1, IRF4), suggesting dysregulated B cell differentiation. Our findings point to impaired lymphocyte responses and increased immunosenescence in NR, emphasizing the need for enhanced vaccine strategies in aging populations.

Quartan malaria caused by Plasmodium malariae (Pm) and tertian Plasmodium ovale (Po) malaria has been largely overlooked in Ethiopia due to their milder clinical symptoms, lower prevalence, and frequently misdiagnosis during routine microscopic. This study estimated the prevalence of Pm and Po infections misdiagnosed as P. vivax (Pv) in selected health facilities in southwestern Ethiopia. A cross-sectional study was conducted among study participants who were positive for Pv by microscopy or rapid diagnostic test (RDT) and who were attending health facilities within Arjo-Didessa sugarcane plantations and surrounding areas in Oromia, southwestern Ethiopia, between September 2019 and July 2022. Of the 3590 febrile patients attending health facilities, 323 were Pv positive by microscopy or RDT. Among these, 245 Pv-positive samples were re-evaluated using quantitative polymerase chain reaction (qPCR). Species-specific primers targeting Pv, P. falciparum (Pf), Pm, and Po were used for species confirmation. From 245 vivax malaria cases, RDT were performed to 162 sub-samples, among them 8.6

Strengthening malaria control and expediting progress toward elimination requires targeting gametocytes to interrupt transmission. Artemisinin-based combination therapy (ACT) effectively clears Plasmodium falciparum asexual parasites and immature gametocytes but has a limited impact on mature gametocytes, which mosquitoes ingest during a blood meal. To address this gap, the World Health Organization recommends adding a single low dose of primaquine (PQ) to ACT regimens. This study assessed the efficacy of a single low-dose PQ for P. falciparum gametocyte clearance and evaluated mosquito infectiousness in Ethiopia. A prospective cohort study was conducted using passive case detection to enrol individuals with uncomplicated P. falciparum malaria at six health facilities. Participants were treated with either ACT alone or ACT plus 0.25 mg/kg single-dose PQ (ACT + PQ) and followed for 28 days with weekly visits. Blood smears for parasite counts, filter paper samples for DNA isolation, and whole blood for RNA preservation were collected on days 0, 7, 14, 21, and 28. On day 7, venous blood was obtained for membrane feeding assays using the Hemotek® system to assess mosquito infection. Logistic regression analysed mosquito infection predictors, while gametocyte prevalence was compared between treatment arms using χ2 or Fisher’s exact tests. Of 304 screened patients, 192 were enroled, with a median age of 23 (IQR 17–30) years; 65.7

Vaccination strategies and correlates of protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have predominantly focused on the spike (S) protein and neutralizing antibodies. However, the rapid emergence of SARS-CoV-2 variants has reduced the effectiveness of spike-based vaccines and monoclonal antibodies. It remains unclear how non-neutralizing antibodies that target the nucleocapsid (N) protein contribute to protection against SARS-CoV-2 variants, especially their ability to trigger antibody effector functions. These antibodies may function by binding to infected cells and initiating antibody-dependent cellular cytotoxicity (ADCC), eliminating infected cells. In this study, we demonstrate that antibodies from individuals who recovered from coronavirus disease 2019 (COVID-19) infection and/or were vaccinated with the S protein vaccine recognize viral proteins on the surface of infected cells and mediate ADCC-mediated NK cell killing of infected cells. Notably, non-neutralizing antibodies induced in COVID-19 infection recognized non-spike proteins on the surface of SARS-CoV-2 variant-infected cells, and these non-neutralizing antibodies cleared SARS-CoV-2 infected cells following depletion of spike antibodies. We identified N and minimal membrane (M) proteins as the targets of non-neutralizing antibodies on the surface of these variant-infected cells. We show that enriched N-specific antibodies from individuals who recovered from COVID-19 infection more consistently killed SARS-CoV-2 variant-infected cells than antibodies to the spike protein. The observed cross-reactivity and robust ADCC activity mediated by N-specific antibodies across various SARS-CoV-2 variant-infected cells highlight the N protein as an important vaccine target in addition to the S protein. Targeting N may provide more comprehensive and durable immunity against SARS-CoV-2 and its evolving variants.

BACKGROUND:Data suggest that antibody responses following COVID-19 vaccines are a correlate of protection. Some studies, including the clinical trials of COVID-19 mRNA vaccines, did not stratify and evaluate whether antibody responses to COVID-19 vaccines differed between the sexes or with aging. This gap in research is particularly relevant for older populations such as nursing home residents (NHR). We hypothesized that sex differences in vaccine-induced antibody responses may intersect with age and be diminished among older adults residing in nursing homes. METHODS:We analyzed serum samples from 638 NHRs collected serially after the primary two-dose series and three subsequent booster doses of mRNA SARS-CoV-2 vaccinations. We analyzed anti-Spike IgG and neutralizing antibody titers to the Wuhan and Omicron BA.4/5 variant strains. Mixed-effects models predicting log-transformed titers were estimated to compare responses across vaccine doses, focusing on sex-differential responses. For detected post-dose sex differences, additional sample times were analyzed to assess the duration of the difference. RESULTS:Following the primary series, female NHRs with a prior history of SARS-CoV-2 infection had significantly higher Wuhan anti-Spike antibodies and neutralizing antibody titers than male NHRs with differences persisting up to nine months post-vaccination. Subsequent monovalent booster doses and a bivalent booster dose eliminated this disparity. We did not detect any differential response to the Omicron BA.4/5 variant. CONCLUSIONS:The blunting of sex differences in antibody response observed following the primary series by the 1st booster dose underscores the importance of booster vaccination in this population.

[This corrects the article DOI: 10.1371/journal.pntd.0004639.].

Annual mass drug administration (MDA) is currently recommended for the local elimination of lymphatic filariasis (LF). Modeling studies of LF transmission suggest that conducting MDA twice a year could accelerate LF elimination. To test this idea, we compared the effects of 3 rounds of yearly MDA and 5 rounds of semiannual MDA using diethylcarbamazine with albendazole on LF infection measures in Papua New Guinea (PNG) across 2 treatment areas with high LF prevalence. From 2013 to 2018, we conducted 4 annual community surveys at 4 sentinel sites in each treatment area. We sampled 2,854 people at the start and 2,746, 2,339, and 2,569 people at 13, 27, and 40 months, respectively, with a similar number of participants in each area. Yearly MDA reduced microfilariae (Mf) prevalence from 24.0% at baseline (95% confidence interval [CI] 22.9-26.1%) to zero (CI, 0-0.4%) at 40 months. Similarly, semiannual MDA lowered Mf prevalence from 23.3% (CI, 21.4-25.4%) to 0.3% (CI, 0.1-0.7%). The circulating filarial antigen (CFA) prevalence decreased from 46.4% at baseline (CI, 43.5-49.3%) to 29.5% (CI, 26.9-32.3%) after 40 months with yearly treatment and from 53.4% (CI, 51.0-55.9%) to 35.2% (CI, 32.7-37.8%) with semiannual MDA. Using a generalized estimating equation model that accounted for age, sex, bednet use, and sentinel site, we found no significant difference in the effectiveness of the two treatment approaches (p = 0.845 for Mf and p = 0.332 for CFA). Therefore, annual and semiannual MDA were equally effective in reducing LF prevalence in this high-endemic setting.

Abstract Background The FDA recently approved the first monovalent XBB1.5 booster vaccine. However, the mechanism by which this vaccine stimulates mucosal and systemic immune responses has been understudied.Figure 1.Impact of XBB 1.5 vaccination on viral neutralization titers using pseudo virus assay (left panel) and ACE2 inhibition assay (right panel).Each dot (white) represents a single serum sample tested in parallel with a post-vaccination sample (colored dot) for each of the 28 participants. The mean fold increase in neutralization titers pre- and post-vaccination are shown for Wuhan, XBB 1.5, and BA5 variants. All increases in neutralization titers are significant to P<0.0001 by employing Wilcoxon matched-pairs signed rank test. Methods We examined 28 participants' serum and saliva one week before and two to three weeks after the XBB1.5 mRNA vaccination for neutralizing and binding antibodies to Wuhan and XBB1.5 S protein.Figure 2:Inhibition of ACE2 binding to different S variants by saliva samples pre- and post-vaccination with XBB1.5 monovalent booster.Paired samples represent the percent ACE2 binding inhibition in participants before and after vaccination. Vaccination induced a 1.7-fold increase in ACE2 neutralization in saliva to XBB1.5 (p<0.0001) and 1.2-fold increase in ACE2 neutralization to Wuhan (p=0.03). Significance tested between pre and post-vaccination by Wilcoxon matched-paired sign rank test. *** p<0.001, **** p<0.0001. Results We observed a 2.9 to 2.6-fold and 5.0 to 7.8-fold increase in Wuhan and XBB1.5 serum neutralization titers following mRNA vaccination using pseudovirus and ACE2 neutralization assays respectively, that closely correlated with a rise in binding antibodies to S protein. Vaccination induced a 1.7-fold increase in ACE2 neutralization in saliva to XBB1.5 (p< 0.0001) and 1.2-fold increase in ACE2 neutralization to Wuhan (p=0.03). This increase in neutralization Ab levels in saliva failed to correlate with the number and time of prior COVID-19 infections, vaccination status, type of vaccine, or concomitant rise in S-specific IgA or IgG in saliva or serum. Depletion of IgA or IgG in saliva following vaccination demonstrated that IgA was primarily responsible for the increase in ACE2 blocking activity (mean reduction in blocking activity with IgA depletion=68%, range, 58-81%) compared to IgG (mean reduction=27%, range 0-71%).Figure 3.Role of IgA on percent reduction in ACE2 inhibition in saliva. Depletion of IgA or IgG in saliva following vaccination demonstrated that IgA was primarily responsible for the increase in ACE2 blocking activity (mean reduction in blocking activity with IgA depletion=68%, range, 58-81%) compared to IgG (mean reduction=27%, range 0-71%). Statistical analysis done using unpaired t test. Conclusion The XBB1.5 monovalent vaccine boosts systemic and mucosal viral neutralization antibody levels, primarily to the XBB1.5 variant. Most people have hybrid immunity to SARS-CoV2 now, so mRNA vaccines boost mucosal immune response better than observed earlier in the pandemic. Increased oral mucosal immunity may reduce the risk of COVID-19 progressing to pneumonia and more severe disease. Disclosures All Authors: No reported disclosures

Abstract Background Immune response and memory changes with aging and disease, features that may be amplified in long-term care populations. We evaluated the kinetics of immunity following vaccination and infection in nursing home residents (NHR). Methods In a cohort of NHR with continuous enrollment since 2020, we drew blood before and after mRNA COVID-19 vaccines and SARS-COV-2 infection. We identified prior and breakthrough infections and the intervals between vaccinations and samples to describe decay kinetics of neutralizing titers over time. Assuming a peak response occurring 14 days after each dose, we estimated mixed-effects exponential decay models, stratified by dose and prior infection and assuming a random intercept for each subject. From these models, we estimated peak value and rates of decay for Wuhan and Omicron BA.4/5 neutralizing titers. Results Our analysis cohort followed 412 NHR (median (IQR) age = 76 (69, 86); 49% female). Among infection-naive NHR, the estimated Wuhan rate of decay did not differ significantly across doses. Prior infected NHR showed significantly longer half-lives after all booster doses than with the primary series (Figure 1, Table 1). Decay models of Omicron BA.4/5 neutralizing titers following booster doses showed significant increases in peak titer for each subsequent booster among both the naive and prior infection subgroups. The decay rates increased significantly over the first monovalent booster, but no differences in rates were detected between infection-naive and prior infection subgroups (Figure 2). The estimated half-lives across strain, dose, and infection subgroups ranged from roughly 50 to 150 days; the differences in peak and decay are reflected in the predicted titers at 6 and 12 months after vaccination (Table 2). Conclusion Following primary series and booster doses, NHR with prior infection enjoy both higher peaks and a similar or slower decline in neutralizing titers than naive NHR, demonstrating the benefits of hybrid immunity with subsequent vaccinations. Neutralizing titers decline sufficiently fast to warrant updating vaccines before the prior dose anniversary. Understanding the kinetics of serial doses within this population can assist in vaccine planning and priorities among NHR. Disclosures Yasin Abul, MD, Moderna: Grant/Research Support|Moderna, Abt, CDC: Grant/Research Support Alejandro Balazs, PhD, Cure Systems LLC: Ownership Interest Stefan Gravenstein, MD, MPH, CDC: Advisor/Consultant|CDC: Grant/Research Support|Genentech: Advisor/Consultant|Genentech: Grant/Research Support|Genentech: Honoraria|GlaxoSmithKline: Advisor/Consultant|GlaxoSmithKline: Grant/Research Support|GlaxoSmithKline: Honoraria|Janssen: Advisor/Consultant|Janssen: Grant/Research Support|Janssen: Honoraria|Moderna: Advisor/Consultant|Moderna: Grant/Research Support|Moderna: Honoraria|NIH: Grant/Research Support|Pfizer: Advisor/Consultant|Pfizer: Grant/Research Support|Pfizer: Honoraria|Sanofi: Advisor/Consultant|Sanofi: Grant/Research Support|Sanofi: Honoraria|Seqirus: Advisor/Consultant David Canaday, MD, Moderna: Grant/Research Support|Pfizer: Grant/Research Support

Background WHO recommends two annual rounds of mass drug administration (MDA) with ivermectin, diethylcarbamazine, and albendazole (IDA) for lymphatic filariasis (LF) elimination in treatment naïve areas that are not co-endemic for onchocerciasis such as Papua New Guinea (PNG). Whether two rounds of MDA are necessary or sufficient and the optimal sampling strategies and endpoints for stopping MDA remain undefined. Methods and findings Two cross-sectional studies were conducted at baseline (N = 49 clusters or villages) and 12 months after mass drug administration (MDA) with IDA (N = 47 villages) to assess lymphatic filariasis (LF) by circulating filarial antigenemia (CFA) and microfilariae (Mf). Before MDA, children aged 6–9 years (N~50) and those ≥ 10 years (N~50) in each village were randomly sampled. Before MDA, the population mean prevalence of LF in East New Britain Province (ENBP), Papua New Guinea, was estimated using population proportionate sampling (PPS, N = 30) to be 59/2,561 (2.3%) CFA positive and 14/2,561 (0.6%) Mf positive. No children were Mf positive. However, LF infection was highly heterogeneous; 8 villages (26.7%) had a CFA prevalence >2%, and 7 villages (23.3%) had an Mf prevalence >1%. To identify sentinel villages with LF in areas under-sampled by PPS, 19 additional villages suspected to have LF were sampled, with 15 (79%) having >2% CFA prevalence and 7 (38%) >1% Mf (range 1–22%). Twenty-four villages were evaluated before and after MDA in age-matched adults ( ≥ 18 years). Treatment reduced CFA prevalence by 34% and Mf prevalence by 90%. Post-MDA model-based geostatistics efficiently selected an additional 23 villages, of which 20 (87%) had a CFA prevalence > 2%. None of these villages had >1% Mf. Post-MDA, two of four districts had no villages with >1% Mf. Conclusions Model-based geostatistics was more effective than PPS in sampling high-risk LF sites in a heterogeneous area. Low LF prevalence and partial reduction of CFA limit children’s effectiveness as sentinels. A single round of high-coverage MDA with IDA achieved elimination targets in low-prevalence villages in PNG. Higher-prevalence areas will need additional MDA rounds, which could be targeted to smaller evaluation units to cut costs. Trial registration Clinicaltrials.gov NCT04124250