Higher Test Positivity Research Articles

Genomic epidemiology demonstrates spatially clustered, local transmission of Plasmodium falciparum in forest-going populations in southern Lao PDR.

While there has been significant progress in controlling falciparum malaria in the Lao People's Democratic Republic (PDR), sporadic cases persist in southern provinces where the extent and patterns of transmission remain largely unknown. To assess parasite transmission in this area, 53 Plasmodium falciparum (Pf) positive cases detected through active test and treat campaigns from December 2017 to November 2018 were sequenced, targeting 204 highly polymorphic amplicons. Two R packages, MOIRE and Dcifer, were applied to assess the multiplicity of infections (MOI), effective MOI (eMOI), within-host parasite relatedness, and between-host parasite relatedness ([Formula: see text]). Genomic data were integrated with survey data to characterize the temporal and spatial structures of identified clusters. The positive cases were mainly captured during the focal test and treat campaign conducted in 2018, and in the Pathoomphone area, which had the highest test positivity and forest activity. About 30% of the cases were polyclonal infections, with over half of theses (63%) showing within-host relatedness greater than 0.6, suggesting that cotransmission rather than superinfection was primarily responsible for maintaining polyclonality. A large majority of cases (81%) were infected by parasites genetically linked to one or more other cases. We identified five genetically distinct clusters in forest fringe villages within the Pathoomphone district, characterized by a high degree of genetic relatedness between parasites (mean [Formula: see text] = 0.8). Four smaller clusters of 2-3 cases linked Moonlapamok and Pathoomphone districts, with an average [Formula: see text] of 0.6, suggesting cross-district transmission. Most of the clustered cases occurred within 20 km and 2 months of each other, consistent with focal transmission. Transmission clusters identified in this study confirm the role of ongoing focal parasite transmission occurring within the forest or forest-fringe in the highly mobile population.

Tuberculosis testing patterns in South Africa to identify groups that would benefit from increased investigation

The National Health Laboratory Service (NHLS) collects all public health laboratory test results in South Africa, providing a cohort from which to identify groups, by age, sex, HIV, and viral suppression status, that would benefit from increased tuberculosis (TB) testing. Using NHLS data (2012–2016), we assessed levels and trends over time in TB diagnostic tests performed (count and per capita) and TB test positivity. Estimates were stratified by HIV status, viral suppression, age, sex, and province. We used logistic regression to estimate the odds of testing positive for TB by viral suppression status. Nineteen million TB diagnostic tests were conducted during period 2012–2016. Testing per capita was lower among PLHIV with viral suppression than those with unsuppressed HIV (0.08 vs 0.32) but lowest among people without HIV (0.03). Test positivity was highest among young adults (aged 15–35 years), males of all age groups, and people with unsuppressed HIV. Test positivity was higher for males without laboratory evidence of HIV than those with HIV viral suppression, despite similar individual odds of TB. Our results are an important national baseline characterizing who received TB testing in South Africa. People without evidence of HIV, young adults, and males would benefit from increased TB screening given their lower testing rates and higher test positivity. These high-test positivity groups can be used to guide future expansions of TB screening.

Geographic Targeting of COVID-19 Testing to Maximize Detection in Los Angeles County.

Many severe acute respiratory syndrome coronavirus 2 infections have not been detected, reported, or isolated. For community testing programs to locate the most cases under limited testing resources, we developed and evaluated quantitative approaches for geographic targeting of increased coronavirus disease 2019 testing efforts. For every week from December 5, 2021, to July 23, 2022, testing and vaccination data were obtained in ∼340 cities/communities in Los Angeles County, and models were developed to predict which cities/communities would have the highest test positivity 2 weeks ahead. A series of counterfactual scenarios were constructed to explore the additional number of cases that could be detected under targeted testing. The simplest model based on most recent test positivity performed nearly as well as the best model based on most recent test positivity and weekly tests per 100 persons in identifying communities that would maximize the average yield of cases per test in the following 2 weeks and almost as well as the perfect knowledge of the actual positivity 2 weeks ahead. In the counterfactual scenario, increasing testing by 1% 2 weeks ahead and allocating all tests to communities with the top 10% of predicted positivity would yield a 2% increase in detected cases. Simple models based on current test positivity can predict which communities may have the highest positivity 2 weeks ahead and hence could be allocated with more testing resources.

Supply-side and demand-side factors influencing uptake of malaria testing services in the community: lessons for scale-up from a post-hoc analysis of a cluster randomised, community-based trial in western Kenya

ObjectivesMaximising the impact of community-based programmes requires understanding how supply of, and demand for, the intervention interact at the point of delivery.DesignPost-hoc analysis from a large-scale community health worker (CHW)...

Population-based assessment of SARS-CoV-2 infection among people living with HIV and the general population of Catalonia (March–December, 2020)

IntroductionIt is unclear if SARS-CoV-2 has affected people living with HIV (PLWH) more. MethodsWe compared SARS-CoV-2 testing, test positivity, hospitalisation, intensive care unit (ICU) admission, and mortality between PLWH and the general HIV-negative population of Catalonia, Spain from March 1 to December 15, 2020. ResultsSARS-CoV-2 testing was lower among PLWH 3556/13,142 (27.06%) compared to the general HIV-negative population 1,954,902/6,446,672 (30.32%) (p<0.001) but test positivity was higher among PLWH (21.06% vs. 15.82%, p<0.001). We observed no significant differences between PLWH and the general population in terms of hospitalisation (13.75% vs. 14.97%, p=0.174) and ICU admission (0.93% vs. 1.66%, p=0.059). Among positive cases, we found a lower mortality rate among PLWH compared to the general population (1.74% vs 3.64%, p=0.002). ConclusionPLWH tested less frequently for SARS-CoV-2, had a higher test positivity, similar ICU admission and hospitalisation rates, and lower SARS-CoV-2-associated mortality compared to the general HIV-negative population.

Malaria surveillance and case management in remote and indigenous communities of Panama: results from a community-based health worker pilot

BackgroundPanama is one of eight countries in Mesoamerica that aims to eliminate malaria by 2022. Malaria is concentrated in indigenous and remote regions like Guna Yala, a politically autonomous region where access to health services is limited and cases are predominately detected through intermittent active surveillance. To improve routine access to care, a joint effort was made by Guna Yala authorities and the Ministry of Health to pilot a network of community health workers (CHWs) equipped with rapid diagnostic tests and treatment. The impact of this pilot is described.MethodsAccess to care was measured using the proportion of villages targeted by the effort with active CHWs. Epidemiological impact was evaluated through standard surveillance and case management measures. Tests for differences in proportions or rates were used to compare measures prior to (October 2014-September 2016) and during the pilot (October 2016-September 2018).ResultsAn active CHW was placed in 39 (95%) of 41 target communities. During the pilot, CHWs detected 61% of all reported cases from the region. Test positivity in the population tested by CHWs (22%) was higher than in those tested through active surveillance, both before (3.8%) and during the pilot (2.9%). From the pre-pilot to the pilot period, annual blood examination rates decreased (9.8 per 100 vs. 8.0 per 100), test positivity increased (4.2% to 8.5%, Χ2 = 126.3, p < 0.001) and reported incidence increased (4.1 cases per 1000 to 6.9 cases per 1000 [Incidence Rate Ratio = 1.83, 95% CI 1.52, 2.21]). The percent of cases tested on the day of symptom onset increased from 8 to 27% and those treated on the day of their test increased from 26 to 84%.ConclusionsThe CHW network allowed for replacement of routine active surveillance with strong passive case detection leading to more targeted and timely testing and treatment. The higher test positivity among those tested by CHWs compared to active surveillance suggests that they detected cases in a high-risk population that had not previously benefited from access to diagnosis and treatment. Surveillance data acquired through this CHW network can be used to better target active case detection to populations at highest risk.

Racial/ethnic and neighbourhood social vulnerability disparities in COVID-19 testing positivity, hospitalization, and in-hospital mortality in a large hospital system in Pennsylvania: A prospective study of electronic health records

BackgroundDisparities in COVID-19 mortality by race/ethnicity or neighborhood have been documented using surveillance data. We aimed to describe disparities by race/ethnicity and neighbourhood social vulnerability in COVID-19 positivity, hospitalization, and mortality.MethodsWe obtained data from the electronic health records of all individuals who tested positive for COVID-19 in the University of Pennsylvania Health System (UPHS) or were hospitalized with confirmed COVID-19 infection in five UPHS hospitals from March 1, 2020, to March 31, 2021. The main predictors were race/ethnicity and neighbourhood-level social vulnerability. The main outcomes were COVID-19 test positivity, hospitalization with COVID-19, and 30-day in-hospital mortality following hospitalization with COVID-19.FindingsA total of 225,129 unique individuals received COVID-19 testing and 18,995 had a positive test result. A total of 5,794 unique patients were hospitalized with COVID-19 and 511 died in-hospital within 30 days. Racial/ethnic minority groups and residents of higher social vulnerability neighbourhoods had higher test positivity and risk of hospitalization. We did not see in-hospital mortality disparities during the first wave but observed 75% and 68% higher odds of death among Hispanic and Asians compared to Whites during subsequent waves.InterpretationWe observed significant racial/ethnic and neighbourhood disparities in COVID-19 outcomes, especially test positivity and odds of hospitalization, highlighting the importance of equitably improving access to preventive measures to reduce SARS-CoV-2 infection, including reducing exposure to the virus and ensuring equity in vaccination.FundingNational Institutes of Health.

Population-based assessment of SARS-CoV-2 infection among people living with HIV and the general population of Catalonia (March–December, 2020)

IntroductionIt is unclear if SARS-CoV-2 has affected people living with HIV (PLWH) more. MethodsWe compared SARS-CoV-2 testing, test positivity, hospitalisation, intensive care unit (ICU) admission, and mortality between PLWH and the general HIV-negative population of Catalonia, Spain from March 1 to December 15, 2020. ResultsSARS-CoV-2 testing was lower among PLWH 3556/13,142 (27.06%) compared to the general HIV-negative population 1,954,902/6,446,672 (30.32%) (p<0.001) but test positivity was higher among PLWH (21.06% vs. 15.82%, p<0.001). We observed no significant differences between PLWH and the general population in terms of hospitalisation (13.75% vs. 14.97%, p=0.174) and ICU admission (0.93% vs. 1.66%, p=0.059). Among positive cases, we found a lower mortality rate among PLWH compared to the general population (1.74% vs 3.64%, p=0.002). ConclusionPLWH tested less frequently for SARS-CoV-2, had a higher test positivity, similar ICU admission and hospitalisation rates, and lower SARS-CoV-2-associated mortality compared to the general HIV-negative population.

Detection of viable Mycobacterium tuberculosis in ocular fluids using mRNA-based multiplex polymerase chain reaction

PurposeIntra ocular tuberculosis (IOTB) can affect nearly any part of the eye and delayed diagnosis can result in permanent loss of vision. mRNA, with the ability to detect viable bacilli just like culture, could serve as an important tool to differentiate whether ocular manifestations of IOTB are due to active infection or hypersensitivity response to dead mycobacteria. MethodsA total of 19 patients with suspected IOTB and 20 controls (10 patients with active inflammation but no evidence of IOTB and 10 patients with no intraocular inflammation) were included. Vitreous fluid samples were collected from all patients and subjected to DNA and mRNA extraction followed by multiplex polymerase chain reaction (MPCR) using three specific targets for M. tuberculosis, i.e. IS6110, MPB64 and protein b. All samples were also subjected to Gene Xpert MTB/RIF assay. ResultsAmong the 19 patients in group 1, the highest test positivity was noted for DNA-MPCR (73.7%) followed by mRNA-MPCR (42.1%) and GeneXpert MTB/RIF assay (10.5%). All the three tests were negative in the 20 control samples demonstrating a 100% specificity. The negative predictive value was highest for DNA-MPCR (80%), followed by mRNA-PCR (64.5%) and Xpert MTB/RIF assay (48.8%). All patients with any one test positive were treated with anti-tubercular therapy (ATT) and there was good clinical response noted in all. ConclusionmRNA-based MPCR can be used as a marker for detecting viable M. tuberculosis in IOTB cases.

Epidemiology and Risk of Coronavirus Disease 2019 Among Travelers at Airport and Port Quarantine Stations Across Japan: A Nationwide Descriptive Analysis and an Individually Matched Case-Control Study.

The epidemiology and risk of coronavirus disease 2019 (COVID-19) among travelers at international borders remain unclear. We conducted descriptive and individually matched case-control studies using a nationwide register for COVID-19 testing of travelers from 3 August to 31 October 2020 at airport/port quarantine stations across Japan. Case patients, defined as travelers positive for COVID-19 on arrival, were individually matched with 4 controls for arrival date and airport or port. We assessed associations between test positivity and traveler characteristics using conditional logistic regression analysis. Overall, 157 507 travelers arriving from 146 countries/areas at 17 quarantine stations across Japan were tested for COVID-19. The percentage of test positivity during the study period was 0.35%. In the case-control study, with 536 case patients and 2144 controls, we found evidence of lower test positivity in travelers aged 3-19 years, female travelers, and travel corridor users (adjusted odds ratio [95% confidence interval], 0.36 [.22-.60], 0.71 [.56-.89], and 0.48 [.30-.77], respectively), whereas higher positivity was associated with arrival from South-East Asia (1.88 [1.33-2.65]) or lower-middle- or low-income countries (2.46 [1.69-3.58] and 7.25 [2.22-23.66], respectively), any symptom (4.08 [1.43-11.65]), and nasopharyngeal compared with saliva sampling (2.75 [1.85-4.09]). A higher 14-day average incidence in the countries of stay was also associated with higher test positivity (1.64 [1.16-2.33] and 3.13 [1.88-5.23] for those from countries and areas where the 14-day average incidence was from 10 to <100 and ≥100 cases per million, respectively). These findings justify travel restrictions based on the epidemic situation in countries of stay, although underestimation of the epidemic in lower-income countries should be considered. A strict travel corridor could also reduce the risk of COVID-19 importation.

Severe Acute Respiratory Syndrome Coronavirus 2 Testing Trends Among Persons Aged

PurposeThe purpose of this study was to analyze trends in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing and test positivity among persons aged <18 years in a three-site outpatient pediatric practice in Atlanta, Georgia, serving approximately 35,000 pediatric patients. MethodsUsing electronic medical records, weekly trends in SARS-CoV-2 tests performed and the 14-day moving average of test positivity were examined, overall and by age group, during May 24–December 5, 2020. ResultsAmong 4,995 patients who received at least 1 SARS-CoV-2 test, 6,813 total tests were completed. Overall test positivity was 5.4% and was higher among older pediatric patients (<5 years: 3.3%; 5–11 years: 4.1%; 12–17 years: 8.6%). The number of tests and test positivity increased after holidays and school breaks. ConclusionsFamilies might benefit from communication focused on reducing SARS-CoV-2 transmission during holidays. In addition, given higher test positivity in children aged 12–17 years, tailoring public health messaging to older adolescents could help limit SARS-CoV-2 transmission risk in this population.

A comparison study of COVID-19 outbreaks in the United States between states with Republican and Democratic Governors

The coronavirus disease 2019 (COVID-19) has caused devastating public health, economic, political, and societal crises. We performed a comparison study of COVID-19 outbreaks in states with Republican governors versus states with Democratic governors in the United States between April 2020 and February 2021. This research study shows that 1) states with Democratic governors had tested more people for COVID-19 and have higher testing rates than those with Republican governors; 2) states with Democratic governors had more confirmed cases for COVID-19 from April 12 until the end of July 2020, as well as from early December 2020 to February 22 2021, and had higher test positivity rates from April 12 until late June 2020, and the states with Republican governors had more confirmed cases from August to early December 2020 and had higher test positivity rates since late June 2020; 3) states with Democratic governors had more deaths for COVID-19 and higher mortality rates than those with Republican governors; 4) more people recovered in states with Democratic governors until early July 2020, while the recovery rate of states with Republican governors is similar to that of states with Democratic governors in May 2020 and higher than that of states with Democratic governors in April 2020 and between June 2020 to February 22 2021. We conclude that our data suggest that states with Republican governors controlled COVID-19 better as they had lower mortality rates and similar or higher recovery rates. States with Democratic governors first had higher test positivity rates until late June 2020 but had lower test positivity rates after July 2020. As of February 2021, the pandemic was still spreading as the daily numbers of confirmed cases and deaths were still high, although the test positivity and mortality rates started to stabilize in spring 2021. This study provides a direct description for the status and performance of handling COVID-19 in the states with Republican governors versus states with Democratic governors, and provides insights for future research, policy making, resource distribution, and administration.

Baseline titres of O, H and AH agglutinins to Salmonella Typhi and Paratyphi A in blood donors in Sri Lanka.

Background: Sri Lanka is considered as an endemic country for enteric fever. Due to difficulties in performing blood cultures, the Widal test is still commonly carried out for the diagnosis of enteric fever. However, there are no published data on current baseline Widal titres in the country. This study was carried out to determine the baseline titres of O, H and AH agglutinins among the Sri Lankan population. Method: Five hundred and one (501) serum samples of blood donors from 31 blood banks in Sri Lanka were collected during 2012 and 2013 and were screened for Salmonella O, H and AH agglutinins using the Widal tube test. A titre of 20 and above was considered positive. Age and gender of the study participants were recorded. Results: Of the 501 sera tested, 58% were positive for at least one of the O, H and AH agglutinins. Salmonella O, H and AH agglutinins were positive in 46.1%, 26.5% and 8.4% of the study population respectively. Of the study population, 97.5% had O, H and AH agglutinin titres less than or equal to 80, 160 and 80 respectively. A significantly higher percentage of females (H-36.7%, p=0.019; AH-15.3%, p=0.15) were positive for H and AH agglutinins than males (H-24.9%; AH-7.4%). The baseline titre of AH agglutinins was higher in females (160) than males or the total population (80). Highest test positivity (40%) was seen among the 31-40 year age group. A significant number of donors below 20 were negative for Salmonella O agglutinins (p=0.024). Conclusion: We recommend baseline titres of 80, 160 and 80 for Salmonella O, H and AH agglutinins respectively to be used in Sri Lankan settings. As there is a variation in baseline titre with age and gender it is necessary to consider both when interpreting Widal test results.

Testing for chlamydial infection: are we meeting clinical guidelines? Evidence from a state-level laboratory data linkage analysis for 15- to 29-year-olds.

All chlamydia tests conducted in Tasmania during 2012-13, for residents aged 15-29 years, were linked. Data linkage allowed individuals who had multiple tests across different healthcare settings to be counted only once each year in analyses. Rates of testing and test positivity by age, sex, rebate status and socioeconomic indicators were measured. There were 31899 eligible tests conducted in 24830 individuals. Testing coverage was higher in females (21%, 19404/92685) than males (6%, 5426/98123). Positivity was higher in males (16%, 862/5426) than females (10%, 1854/19404). Most tests (81%, 25803/31899) were eligible for a rebate. Positivity was higher in females with non-rebatable tests (12%, 388/3116 compared with those eligible for a rebate (9%, 1466/16285). More testing occurred in areas of middle disadvantage (10%, 9688/93678) compared with least (8%, 1680/21670) and most (10%, 7284/75460) (both P<0.001) disadvantaged areas. Higher test positivity was found in areas of most-disadvantage (11%, 822/7284) compared with middle- (10%, 983/9688) and least- (8%, 139/1680) disadvantaged areas. Chlamydia testing rates are lower than recommended levels. Sustaining the current testing rates in females aged 20-24 years may reduce population prevalence within 10 years. This study meets key priorities of national strategies for chlamydia control by providing a method of monitoring testing coverage and evidence to evaluate prevention programs.

Who tests whom? A comprehensive overview of Chlamydia trachomatis test practices in a Dutch region among different STI care providers for urogenital, anorectal and oropharyngeal sites in young people: a cross-sectional study

ObjectivesTo evaluate and compare Chlamydia trachomatis (CT) diagnostic test practices of different sexually transmitted infection (STI) care providers in 16–29 year olds from one defined geographic Dutch region (280 000...