Introduction:Tuberculosis (TB) remains a major public health concern in Fiji, but genomic data on the circulating Mycobacterium tuberculosis complex (MTBC) are limited. Methods:We analysed 65 MTBC isolates collected during 2019-2022 using whole-genome sequencing to characterize lineage distribution, drug resistance, and transmission patterns. Results:Of the isolates, 62 (95.4%) were Mycobacterium tuberculosis and 3 (4.6%) were Mycobacterium bovis. Lineage 4 was the most common (29/62, 46.8%). Genomic analysis identified 12 transmission clusters, with epidemiological links involving households, schools, and neighbouring communities. Most MTBC isolates (57/65, 87.7%) were susceptible to first-line anti-TB drugs; however, 8 (12.3%) carried resistance-associated mutations in katG, rpoB, rrs, or pncA. Treatment outcomes indicated that 20 (30.8%) patients were lost to follow-up. Discussion:Detection of M. bovis suggests possible zoonotic transmission and highlights limitations of routine diagnostics. These findings indicate diverse MTBC lineages and localized transmission networks, supporting integration of genomic surveillance into TB control efforts in Fiji.

Scabies is a neglected tropical skin disease that is endemic in Pacific Island countries. Ivermectin-based mass drug administration (MDA) trials have led to reductions in scabies and impetigo prevalence. The World Scabies Program supported ministries of health with national scabies MDA campaigns in Solomon Islands (two annual rounds, 2022–2024) and Fiji (one round, 2022). Here we conducted population-based national prevalence surveys before and after MDA in both countries to assess scabies and impetigo prevalence. We compared scabies and impetigo prevalence before MDA with the prevalence 6 to 12 months after. Over 9,000 participants were surveyed at each time point. In Solomon Islands, following two MDA rounds, scabies prevalence decreased from 23.2% to 3.9% while impetigo prevalence decreased from 9.2% to 1.6%. In Fiji, scabies prevalence decreased from 6.2% to 3.4% and that of impetigo decreased from 4.3% to 1.2%. We observed substantial reductions in the prevalence of scabies and impetigo following MDA in both countries, providing evidence to support similar large-scale scabies interventions. Nationwide population-based surveys in Solomon Islands and Fiji, involving more than 9,000 participants at each survey time point, found that there was a reduced scabies and impetigo prevalence for 6–12 months after ivermectin-based mass drug administration.

Antibiotics disrupt mucosal microbial communities, yet the effects on microbiomes infected with Chlamydia trachomatis (Ct) remain poorly understood. Some data exist on vaginal microbiomes, but none exist for the endocervix or rectum that are primary sites of infection. We applied metagenomic shotgun sequencing to vaginal, endocervical and rectal samples collected longitudinally from women who cleared their infection post-treatment (n = 10), had persistent infection (n = 11), or remained uninfected (n = 18) to evaluate azithromycin-induced changes in microbial composition, function, and the resistome over time. Our results show shifts in composition and function post-treatment that support persistent Ct, nonsynonymous Ct L22 amino acid substitutions that may be linked to azithromycin resistance, and significant endocervical increases in azithromycin resistance genes in Lactobacillus iners and Gardnerella vaginalis strains with moderate/high biofilm formation potential. These findings highlight the unintended ecological consequences of azithromycin treatment, including likely resistance gene propagation, emphasizing the need for novel treatment and microbiome-preserving strategies.

Background The coronavirus disease 2019 pandemic impact on sexually transmitted infections in countries practicing syndromic management remains unknown. We conducted cross-sectional surveys in Fiji to assess increases and risk factors for Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT) infections pre- and postpandemic. Methods We enrolled women, men who have sex only with women (MSW), and men who have sex with men (MSM) aged 18-40 years, collected sociodemographic/behavioral data, and tested vaginal, urethral, and rectal samples using Xpert-CT/NG. Risk factors were evaluated using regression models. Results Of 1955 participants, 6.4% (95% confidence interval [CI], 5.4%-7.6%) had gonorrhea, increasing significantly postpandemic >2-fold among women aged 25-40 years and >4-fold among MSM, MSW, and men aged 18-24 and 25-40 years; 20.0% (95% CI, 18.3%-21.8%) had chlamydia, increasing significantly postpandemic among younger women and approximately 2- to 4-fold among MSW and younger and older men. Increases were driven by urethral/vaginal infections. Coinfections increased significantly postpandemic among older women. Postpandemic gonorrhea was associated with difficulty obtaining condoms (adjusted relative risk [aRR], 2.7 [95% CI, 1.0-8.0]) and >= 2 partners (aRR, 2.6 [95% CI, 1.0-7.1]) among younger women, and iTaukei ethnicity (aRR, 4.7 [95% CI, 1.4-16.5]) and heavy alcohol use (aRR, 7.1 [95% CI, 2.5-19.7]) among older women. Postpandemic chlamydia was associated with having a casual sex partner among younger (aRR, 1.7 [95% CI, 1.0-2.9]) and older (aRR, 1.9 [95% CI, 1.1-3.4]) women and with being unmarried (aRR, 1.7 [95% CI, 1.0-2.7]). iTaukei men had increased risk postpandemic for gonorrhea (aRR, 3.7 [95% CI, 1.3-10.6]) and chlamydia (aRR, 2.5 [95% CI, 1.3-4.9]). More than 50% of infected participants did not meet syndromic treatment criteria and would have remained untreated. Conclusions Postpandemic increases in gonorrhea and chlamydia-with risk factors varying by pathogen, gender, and age-require immediate interventions to reduce infection and transmission in Fiji.

Antibiotics disrupt mucosal microbial communities, yet the effects on microbiomes with Chlamydia trachomatis (Ct) infection remain poorly understood. Some data exist on vaginal microbiomes pre- and post-treatment, but none are available for the endocervix or rectum that are primary sites of infection. We applied metagenomic shotgun sequencing to vaginal, endocervical and rectal samples from women who, overtime, had Ct persistence, clearance, or no infection to evaluate azithromycin-induced changes in microbial composition, function, and the resistome. Our results show a shift in composition and function that support Ct post-treatment with azithromycin resistance mutations in the Ct rplV gene and significant endocervical enrichment of azithromycin resistance genes in Lactobacillus iners and Gardnerella vaginalis, the strains of which have moderate/high potential for biofilm formation. These findings highlight the unintended ecological consequences of azithromycin, including resistance gene propagation and microbiome shifts that support persistent/recurrent Ct, emphasizing the need for novel treatment and microbiome-preserving strategies.

IntroductionChlamydia trachomatis, a gram-negative obligate intracellular bacterium, commonly causes sexually transmitted infections (STIs). Little is known about C. trachomatis transmission within the host, which is important for understanding disease epidemiology and progression.MethodsWe used RNA-bait enrichment and whole-genome sequencing to compare rectal, vaginal and endocervical samples collected at the same time from 26 study participants who attended Fijian Ministry of Health and Medical Services clinics and tested positive for C. trachomatis at each anatomic site.ResultsThe 78 C. trachomatis genomes from participants resolved into two major clades of the C. trachomatis phylogeny (the “prevalent urogenital and anorectal” clade and “non-prevalent urogenital and anorectal” clade). For 21 participants, genome sequences were almost identical in each anatomic site. For the other five participants, two distinct C. trachomatis strains were present in different sites; in two cases, the vaginal sample was a mixture of strains.DiscussionThe absence of large numbers of fixed SNPs between C. trachomatis genomes within many of the participants could indicate recent acquisition of infection prior to the clinic visit without sufficient time to accumulate significant genetic variation in different body sites. This model suggests that many C. trachomatis infections may be resolved relatively quickly in the Fijian population, possibly reflecting common prescription or over-the-counter antibiotics usage.

OBJECTIVES:Fiji could be the first country to eliminate tuberculosis. To inform this strategy, we aimed to identify how many GeneXpert® machines are required to enable over 90% of Fijians to be within one-hour easy access. METHODS:We used Geographic Information System (Quantum GIS; QGIS), OpenStreetMap and population data (Kontur) to map possible facilities in relation to QGIS generated 60-min drive-time isochrones, with correction for missing road data. For outer islands, we calculated a distance to nearest hub operation. RESULTS:The solution comprised 24 GeneXpert® machines, allocating 7 GeneXpert® to Viti Levu, 6 GeneXpert® to Vanua Levu and 11 to other islands. This resulted in 827,810 people, 93.6% of Fiji's population, being within 1 h of a machine. Twenty-one thousand four hundred seventy-nine people on outer islands were an average of 43 km by water from the nearest facility. CONCLUSIONS:We conclude that over 90% of Fijians could be within an hour of a GeneXpert® machine with placement of 24 machines.

Scabies and related bacterial skin and soft tissue infections (SSTIs) are highly prevalent in many tropical, low- and middle-income settings. These skin conditions contribute to higher healthcare costs and burdens on healthcare systems. The Big Skin Health Intervention Fiji Trial (“Big SHIFT”) carried out surveillance for scabies and SSTIs from July 2018 to June 2019 in the Northern Division of Fiji, an area with high prevalence of scabies, prior to a division-wide ivermectin-based mass drug administration (MDA) campaign. Using data from Big SHIFT, we sought to estimate the annual direct healthcare costs of scabies and related SSTIs for the Northern Division and extrapolate these costs to the national level. We categorized SSTIs as being potentially scabies-related or unlikely scabies-related, based on a previous study. The analysis used a health system perspective, with the main resource use categories of outpatient visits, bed days during admissions, medicines, and diagnostic tests. We extrapolated the total annual number of cases and direct healthcare costs for all divisions in Fiji based upon previous scabies and impetigo prevalence data across all divisions. The average cost per PHC presentation for scabies was US$17.7, and for potentially scabies-related SSTI was $18.3. The average cost per hospital admission for a potentially scabies-related SSTI case was $439. The estimated annual healthcare costs of scabies and related SSTIs in Fiji was US$3.0 million, with cost per capita of $3.3. Scabies and related SSTIs lead to a heavy economic burden in Fiji and prevention would reduce these healthcare costs.

ABSTRACTPacific Islanders (PI) are a vulnerable population with a high prevalence of Chlamydia trachomatis (Ct) sexually transmitted infections and remain underrepresented in research. Here, 258 vaginal and 92 paired endocervical samples from women of diverse ethnicities in Fiji were analyzed using metagenomic shotgun sequencing. Using VALENCIA, a sub-community state type (subCST) classifier, 93 (36.04%) vaginal and 38 (41.30%) endocervical microbiomes did not match reference subCSTs. We, therefore, designed four unique subCSTs, IV-D0, IV-D1, IV-D2, and IV-E—differentially dominated by Gardnerella vaginalis, Prevotella spp., and Lactobacillus iners—to improve microbiome classifications. Ct-infected paired endocervical and vaginal microbiomes were significantly more likely to have differential species relative abundance (81.58%) than uninfected pairs (35.84%; adjusted odds ratio, 7.93; 95% confidence interval, 2.93–21.93; P < 0.0001). Among paired microbiomes, the endocervix had a significantly higher alpha diversity and independently a higher alpha diversity for high-risk human papilloma virus (HPV) types compared to low-risk and no HPV. The Ct-infected endocervical network compared to all others had smaller clusters—indicating lower species abundance and decreased weight of interactions among bacterial groups within clusters—and no interactions with potentially beneficial Lactobacillus spp. These data suggest a distinct influence on this network from Ct-infected endocervical cells. Furthermore, the high relative abundance of G. vaginalis and Prevotella spp. may generate polymicrobial biofilms that predispose to and/or promote Ct and possibly HPV persistence and pathogenicity. While these data expand on the existing repertoire of endocervical and vaginal microbiomes and fill in knowledge gaps regarding PIs, prospective studies are needed to define causal associations to develop successful interventions.IMPORTANCEChlamydia trachomatis (Ct) is the most common sexually transmitted bacterium globally. Endocervical and vaginal microbiome interactions are rarely examined within the context of Ct or among vulnerable populations. We evaluated 258 vaginal and 92 paired endocervical samples from Fijian women using metagenomic shotgun sequencing. Over 37% of the microbiomes could not be classified into sub-community state types (subCSTs). We, therefore, developed subCSTs IV-D0, IV-D1, IV-D2, and IV-E—dominated primarily by Gardnerella vaginalis—to improve classification. Among paired microbiomes, the endocervix had a significantly higher alpha diversity and, independently, higher diversity for high-risk human papilloma virus (HPV) genotypes compared to low-risk and no HPV. Ct-infected endocervical networks had smaller clusters without interactions with potentially beneficial Lactobacillus spp. Overall, these data suggest that G. vaginalis may generate polymicrobial biofilms that predispose to and/or promote Ct and possibly HPV persistence and pathogenicity. Our findings expand on the existing repertoire of endocervical and vaginal microbiomes and fill in knowledge gaps regarding Pacific Islanders.

Background In 2008/9, Fiji vaccinated >30,000 girls aged 9-12 years with the quadrivalent human papillomavirus (4vHPV) vaccine coverage for at least one dose was >60% (one dose only was 14%, two dose only was 13%, three doses was 35%). We calculated vaccine effectiveness (VE) of one, two and three doses of 4vHPV against oncogenic HPV genotypes 16/18, eight years following vaccination. Methods A retrospective cohort study was undertaken (2015-2019) in pregnant women <= 23 years old, eligible to receive 4vHPV in 2008/9, with confirmed vaccination status. The study was restricted to pregnant women due to the cultural sensitivity of asking about sexual behavior in Fiji. For each participant a clinician collected a questionnaire, vaginal swab and genital warts examination, a median eight (range 6-11) years post vaccination. HPV DNA was detected by molecular methods. Adjusted VE (aVE) against the detection of vaccine HPV genotypes (16/18), the comparison group of non-vaccine genotypes (31/33/35/39/45/51/52/56/58/59/66/68), and genital warts were calculated. Covariates included in the adjusted model were: age, ethnicity and smoking, according to univariate association with any HPV detection. Findings Among 822 participants the prevalence of HPV 16/18 in the unvaccinated, one, two and three-dose groups were 13.3% (50/376), 2.5% (4/158), 0% (0/99) and 1.6% (3/189), respectively; and for the non-vaccine high-risk genotypes, the detection rate was similar across dosage groups (33.2%-40.4%, p = 0.321). The aVE against HPV 16/18 for one, two and three doses were 81% (95% CI; 48-93%), 100% (95% CI; 100-100%), and 89% (95% CI; 64-96%), respectively. Prevalence of HPV 16/18 was lower among women with longer time since vaccination. Interpretations A single dose 4vHPV vaccine is highly effective against HPV genotypes 16 and 18 eight years following vaccination. Our results provide the longest duration of protection for reduced dose 4vHPV schedule in a low- or middle-income country in the Western Pacific region. Copyright (c) 2023 Published by Elsevier Ltd.

The Pacific Island countries of the Western Pacific Region have some of the highest rates of sexually transmitted Chlamydia trachomatis and Neisseria gonorrhoeae infections in the world. Despite this, there are few research studies that include Pacific Islanders. We conducted a narrative review of original research and surveys, including World Health Organization and Pacific Community reports, to determine the prevalence, management, and treatment of C. trachomatis and N. gonorrhoeae compared to HIV and syphilis from 1980 to 2022. Available epidemiologic data on C. trachomatis and N. gonorrhoeae indicated an extremely high prevalence-approximately 30% and 13%, respectively-among Pacific Islanders during this timeframe. These neglected sexually transmitted infections represent a significant burden and health disparity. Robust epidemiologic research is needed to identify modifiable risk factors for designing interventions and control strategies. Appropriate policies along with regional and international advocacy and aid are required to improve reproductive health among these vulnerable, understudied populations to avert preventable infections and sequelae.

Leptospirosis, a global zoonotic disease, is prevalent in tropical and subtropical regions, including Fiji where it’s endemic with year-round cases and sporadic outbreaks coinciding with heavy rainfall. However, the relationship between climate and leptospirosis has not yet been well characterised in the South Pacific. In this study, we quantify the effects of different climatic indicators on leptospirosis incidence in Fiji, using a time series of weekly case data between 2006 and 2017. We used a Bayesian hierarchical mixed-model framework to explore the impact of different precipitation, temperature, and El Niño Southern Oscillation (ENSO) indicators on leptospirosis cases over a 12-year period. We found that total precipitation from the previous six weeks (lagged by one week) was the best precipitation indicator, with increased total precipitation leading to increased leptospirosis incidence (0.24 [95% CrI 0.15–0.33]). Negative values of the Niño 3.4 index (indicative of La Niña conditions) lagged by four weeks were associated with increased leptospirosis risk (-0.2 [95% CrI -0.29 –-0.11]). Finally, minimum temperature (lagged by one week) when included with the other variables was positively associated with leptospirosis risk (0.15 [95% CrI 0.01–0.30]). We found that the final model was better able to capture the outbreak peaks compared with the baseline model (which included seasonal and inter-annual random effects), particularly in the Western and Northern division, with climate indicators improving predictions 58.1% of the time. This study identified key climatic factors influencing leptospirosis risk in Fiji. Combining these results with demographic and spatial factors can support a precision public health framework allowing for more effective public health preparedness and response which targets interventions to the right population, place, and time. This study further highlights the need for enhanced surveillance data and is a necessary first step towards the development of a climate-based early warning system.

Background Pacific Islanders are a vulnerable population with a high prevalence of Chlamydia trachomatis ( Ct ) sexually transmitted infections (STIs) and remain underrepresented in research. Here, 258 vaginal and 92 paired endocervical samples from women of diverse ethnicities in Fiji were evaluated using metagenomics to characterize microbial relative abundance, composition and networks including associations with Neisseria gonorrhoeae , human papilloma virus (HPV), Mycoplasma genitalium , Candida and bacterial vaginosis (BV). Results Pacific Islander ethnicities and age <25 years were significantly associated with Ct infection. Using VALENCIA, a sub-community state type (subCST) classifier, 93 (36.04%) vaginal and 38 (41.30%) endocervical microbiomes did not match reference subCSTs. Four unique subCSTs were developed to better classify Pacific Islander microbiomes: IV-D0, dominated by Gardnerella vaginalis ; IV-D1, high/moderate G. vaginalis relative abundance with Prevotella spp.; IV-D2, high/moderate G. vaginalis with Lactobacillus iners ; and IV-E, moderate Prevotella spp . Ct positive endocervical and paired vaginal microbiomes were significantly more likely to have differential species relative abundance (81.58%) than Ct negative pairs (35.84%; AOR: 7.93; 95% CI: 2.93-21.93; P <0.0001). A significantly higher alpha diversity was found for iTaukei ethnicity, all subCST-IV types, BV, and Ct for vaginal microbiomes. For endocervical microbiomes, higher diversity was significant for subCST-IV-A, subCST-IV-D1, and subCST-IV-E, and high-risk HPV types. Overall, there was a significantly higher diversity for the endocervix in paired microbiomes. Vaginal microbiomes showed significant divergence in community composition as above and for Candida. Endocervical composition varied significantly by subCST type and Ct status. Gut and BV-associated bacterial clusters were present in Ct positive and negative paired endocervical and vaginal microbiome networks but were smaller with fewer bacterial and no Lactobacillus spp. interactions in Ct -infected endocervical networks where G. vaginalis generated polymicrobial biofilms along with Ct likely influence pathogenicity. Conclusions Fijian endocervical and vaginal microbiomes represent divergent microbial abundance and compositions, especially for Pacific Islander ethnicities, with distinct subCSTs compared to other global populations. The higher microbial diversity of the endocervix with prevalent G. vaginalis , L. iners and Prevotella spp. suggest that these microbiomes/networks may predispose to and/or promote chlamydial and HPV pathogenesis. Prospective studies are needed to further define causal associations to develop successful interventions.

In 2019, the Murdoch Children’s Research Institute in partnership with the Fiji Ministry of Health and Medical Services carried out an integrated mass drug administration (MDA) for the treatment of scabies and lymphatic filariasis in the Northern Division of Fiji (population estimate 131,914). We conducted a retrospective micro-costing exercise focused on the cost of scabies control in order to inform budgeting and policy decision making in an endemic setting. We collected detailed information on financial and economic costs incurred by both parties during the course of the MDA campaign (April 2018 to July 2019). We also conducted interviews with personnel involved in the financial administration of the MDA campaign. The economic cost of delivering two doses of ivermectin was US$4.88 per person. The cost of donated drugs accounted for 36.3% of total MDA costs. In this first large-scale MDA for the public health control of scabies, the estimated cost of delivering MDA per person for scabies was considerably more expensive than the costs reported for other neglected tropical diseases. The important cost drivers included the remuneration of health care workers who were extensively involved in the campaign, coverage of hard-to-reach, mainly rural populations and the two-dose regimen of ivermectin. These results highlight the importance of these cost determinants and can be used to plan current and future MDA programs.

BackgroundIn 2012, Fiji introduced the 10-valent pneumococcal conjugate vaccine (PCV10). We assessed the impact of PCV10 on invasive pneumococcal disease (IPD), probable bacterial or pneumococcal meningitis (PBPM), meningitis and sepsis 3-5 years post-introduction.MethodsLaboratory-confirmed IPD and PBPM cases were extracted from national laboratory records. ICD-10-AM coded all-cause meningitis and sepsis cases were extracted from national hospitalisation records. Incidence rate ratios were used to compare outcomes pre/post-PCV10, stratified by age groups: 1-23m, 2-4y, 5-9y, 10-19y, 20-54y, ≥55y. To account for different detection and serotyping methods in the pre-and post-PCV10 period, a Bayesian inference model estimated serotype-specific changes in IPD, using pneumococcal carriage and surveillance data.FindingsThere were 423 IPD, 1,029 PBPM, 1,391 all-cause meningitis and 7,611 all-cause sepsis cases. Five years post-PCV10 introduction, IPD declined by 60% (95%CI: 37%, 76%) in children 1-23m months old, and in age groups 2-4y, 5-9y, 10-19y although confidence intervals spanned zero. PBPM declined by 36% (95%CI: 21%, 48%) among children 1-23 months old, and in all other age groups, although some confidence intervals spanned zero. Among children <5y of age, PCV10-type IPD declined by 83% (95%CI; 70%, 90%) and with no evidence of change in non-PCV10-type IPD (9%, 95%CI; -69, 43%). There was no change in all-cause meningitis or sepsis. Post-PCV10, the most common serotypes in vaccine age-eligible and non-age eligible people were serotypes 8 and 23B, and 3 and 7F, respectively.InterpretationsOur study demonstrates the effectiveness of PCV10 against IPD in a country in the Asia-Pacific of which there is a paucity of data.FundingThis study was support by the Department of Foreign Affairs and Trade of the Australian Government and Fiji Health Sector Support Program (FHSSP). FHSSP is implemented by Abt JTA on behalf of the Australian Government.

Background:Scabies is an important predisposing factor of impetigo which can lead to serious bacterial complications. Ivermectin-based mass drug administration can substantially reduce scabies and impetigo prevalence in endemic settings, but the impact on serious bacterial complications is not known. Methods:We conducted a before-after trial in the Northern Division of Fiji (population: 131,914) of mass drug administration for scabies control. Prospective surveillance was conducted from 2018 to 2020. Mass drug administration took place in 2019, involving two doses of oral ivermectin or topical permethrin, delivered alongside diethylcarbamazine and albendazole for lymphatic filariasis. The primary outcomes were incidence of hospitalisations with skin and soft tissue infections, and childhood invasive infections and post-streptococcal sequelae. Secondary outcomes included presentations to primary healthcare with skin infections and community prevalence of scabies and impetigo. Findings:The incidence of hospitalisations with skin and soft tissue infections was 17% lower after the intervention compared to baseline (388 vs 467 per 100,000 person-years; incidence rate ratio 0.83, 95% CI, 0.74 to 0.94; P = 0.002). There was no difference in incidence of childhood invasive infections and post-streptococcal sequelae. Incidence of primary healthcare presentations with scabies and skin infections was 21% lower (89.2 vs 108 per 1000 person-years, incidence rate ratio, IRR 0.79, 95% CI, 0.78 to 0.82). Crude community prevalence of scabies declined from 14.2% to 7.7% (cluster-adjusted prevalence 12.5% to 8.9%; prevalence ratio 0.71, 95% CI, 0.28 to 1.17). Cluster-adjusted prevalence of impetigo declined from 15.3% to 6.1% (prevalence ratio 0.4, 95% CI, 0.18 to 0.86). Interpretation:Mass drug administration for scabies control was associated with a substantial reduction in hospitalisations for skin and soft tissue infections. Funding:National Health and Medical Research Council of Australia and Scobie and Claire Mackinnon Trust.

BackgroundLeptospirosis is a zoonotic disease prevalent throughout the world, but with particularly high burden in Oceania (including the Pacific Island Countries and Territories). Leptospirosis is endemic in Fiji, with outbreaks often occurring following heavy rainfall and flooding. As a result of non-specific clinical manifestation and diagnostic challenges, cases are often misdiagnosed or under-ascertained. Furthermore, little is known about the duration of persistence of antibodies to leptospirosis, which has important clinical and epidemiological implications.Methodology and principal findingsUsing the results from a serosurvey conducted in Fiji in 2013, we fitted serocatalytic models to estimate the duration of antibody positivity and the force of infection (FOI, the rate at which susceptible individuals acquire infection or seroconversion), whilst accounting for seroreversion. Additionally, we estimated the most likely timing of infection. Using the reverse catalytic model, we estimated the duration of antibody persistence to be 8.33 years (4.76-12.50; assuming constant FOI) and 7.25 years (3.36-11.36; assuming time-varying FOI), which is longer than previous estimates. Using population age-structured seroprevalence data alone, we were not able to distinguish between these two models. However, by bringing in additional longitudinal data on antibody kinetics we were able to estimate the most likely time of infection, lending support to the time-varying FOI model. We found that most individuals who were antibody-positive in the 2013 serosurvey were likely to have been infected within the previous two years, and this finding is consistent with surveillance data showing high numbers of cases reported in 2012 and 2013.ConclusionsThis is the first study to use serocatalytic models to estimate the FOI and seroreversion rate for Leptospira infection. As well as providing an estimate for the duration of antibody positivity, we also present a novel method to estimate the most likely time of infection from seroprevalence data. These approaches can allow for richer, longitudinal information to be inferred from cross-sectional studies, and could be applied to other endemic diseases where antibody waning occurs.

ABSTRACT. Typhoid is an endemic in Fiji with increases observed since the early 2000s and frequent outbreaks reported. We assessed the diagnostic accuracy of currently available typhoid rapid diagnostic tests (RDTs) (TUBEX, Typhidot Rapid, and Test-It assay) to establish their performance against blood culture in Fiji and to examine their suitability for rapid typhoid outbreak identification. The performance of RDTs was assessed in the public health reference laboratory in Suva, Fiji, according to the manufacturers’ instructions. A simulation was used to examine the potential use of RDTs for attribution of a febrile illness outbreak to typhoid. For the diagnostic evaluation, 179 patients were included; 49 had blood culture–confirmed typhoid, 76 had fever as a result of non-typhoid etiologies, and 54 were age-matched community controls. The median (interquartile range) age was 29 (20–46) years. Of the participants, 92 (51.4%) were male and 131 (73.2%) were indigenous Fijians. The sensitivities of the tests were 77.6% for TUBEX, 75.5% for Typhidot Rapid, and 57.1% for Test-It assay. The Test-It assay had the highest specificity of 93.4%, followed by Typhidot Rapid 85.5% and TUBEX 60.5%. Typhidot Rapid had the best performance in the simulation for attribution of a febrile illness outbreak to typhoid. Typhoid RDTs performed suboptimally for individual patient diagnosis due to low sensitivity and variable specificity. We demonstrate that RDTs could be useful in the field for rapid attribution of febrile illness outbreaks to typhoid. Typhidot Rapid had the best combination of sensitivity, specificity, positive and negative predictive values, cost, and ease of use for this purpose.

Background Scabies causes considerable morbidity in disadvantaged populations. The International Alliance for the Control of Scabies (IACS) published consensus criteria in 2020 to standardize scabies diagnosis. However, these criteria are complex, and a WHO informal consultation proposed simplified criteria for mapping, to identify regions of high prevalence as targets for mass drug administration. We aimed to investigate the accuracy of simplified criteria in determining scabies prevalence, compared to the 2020 IACS criteria. Methods We obtained data relating to demographics, relevant history and skin lesions from all-age prevalence surveys from Fiji ( n = 3365) and Solomon Islands ( n = 5239), as well as school-aged children in Timor-Leste ( n = 1043). We calculated prevalence using the 2020 IACS criteria and simplified criteria and compared these disease estimates. Results There was no significant difference in the pooled prevalence using the two methods (2020 IACS criteria: 16.6%; simplified criteria: 15.6%; difference = 0.9, [95% CI -0.1, 2.0]). In Timor-Leste, the prevalence using simplified criteria was lower (26.5% vs 33.8%). Simplified criteria had a sensitivity of 82.3% (95% CI 80.2, 84.2) and specificity of 97.6% (95% CI 97.2, 97.9) compared to the 2020 IACS criteria. Conclusions The scabies prevalence estimation using simplified criteria was similar to using the 2020 IACS criteria in high prevalence, tropical countries. The prevalence estimation was lower in the school-based survey in Timor-Leste. Mapping using simplified criteria may be a feasible and effective public health tool to identify priority regions for scabies control. Further work assessing use of simplified criteria for mapping in a field setting should be conducted.