No Serological Evidence of Trachoma or Yaws Among Residents of Registered Camps and Makeshift Settlements in Cox’s Bazar, Bangladesh

Abstract

Successful achievement of global targets for elimination of trachoma as a public health problem and eradication of yaws will require control efforts to reach marginalized populations, including refugees. Testing for serologic evidence of transmission of trachoma and yaws in residents of registered camps and a Makeshift Settlement in Cox’s Bazar District, Bangladesh, was added to a serosurvey for vaccine-preventable diseases (VPDs) conducted April–May 2018. The survey was primarily designed to estimate remaining immunity gaps for VPDs, including diphtheria, measles, rubella, and polio. Blood specimens from 1- to 14-year-olds from selected households were collected and tested for antibody responses against antigens from Treponema pallidum and Chlamydia trachomatis using a multiplex bead assay to evaluate for serologic evidence of the neglected tropical diseases (NTDs) yaws and trachoma, respectively. The prevalence of antibodies against two C. trachomatis antigens in children ranged from 1.4% to 1.5% for Pgp3 and 2.8% to 7.0% for CT694. The prevalence of antibody responses against both of two treponemal antigens (recombinant protein17 and treponemal membrane protein A) tested was 0% to 0.15% in two camps. The data are suggestive of very low or no transmission of trachoma and yaws, currently or previously, in children resident in these communities. This study illustrates how integrated serologic testing can provide needed data to help NTD programs prioritize limited resources.

Performance of SARS-CoV-2 Antigens in a Multiplex Bead Assay for Integrated Serological Surveillance of Neglected Tropical and Other Diseases

“…38 Additionally, serology is becoming increasingly used to estimate prevalence to help programs prioritize where to focus interventions. 39 , 40 Multiplex testing of DBS collected during a serosurvey triggered by a diphtheria outbreak in refugee camps in Cox’s Bazar, Bangladesh, showed little evidence of malaria, 22 trachoma, 17 or yaws. 17 An NTD collateral benefits study provided critical data to show tetanus immunity gaps in East African adult men.…”

“… 39 , 40 Multiplex testing of DBS collected during a serosurvey triggered by a diphtheria outbreak in refugee camps in Cox’s Bazar, Bangladesh, showed little evidence of malaria, 22 trachoma, 17 or yaws. 17 An NTD collateral benefits study provided critical data to show tetanus immunity gaps in East African adult men. 25 Unknown pockets of Strongyloides stercoralis infection in Cambodia were revealed by multiplex testing of specimens from a VPD serosurvey.…”

“… 14 Multiplex bead assays (MBA) used for integrated serological surveillance could add value to COVID-19 serosurveys by simultaneously testing for other infections of public health interest. 15 , 16 We have used MBA for integrated serosurveillance of neglected tropical diseases (NTDs), 16 – 19 malaria, 20 – 22 waterborne diseases, 23 , 24 and measuring seroprotection to vaccine preventable diseases (VPDs) 25 to obtain additional information on disease burden, susceptibility to vaccine-preventable diseases, and progress toward disease elimination targets.…”

Monitoring transmission intensity of trachoma with serology

“…Based on examples from other infectious diseases including malaria 9 and SARS-CoV-2, 10 use cases for trachoma serology may include monitoring population-level transmission to determine appropriate interventions, post-validation surveillance, opportunistic investigation of populations using blood collected for other purposes, and fine-scale geographic targeting of control measures. 11–13…”

“…Based on examples from other infectious diseases including malaria 9 and SARS-CoV-2, 10 use cases for trachoma serology may include monitoring population-level transmission to determine appropriate interventions, post-validation surveillance, opportunistic investigation of populations using blood collected for other purposes, and fine-scale geographic targeting of control measures. [11][12][13] IgG antibody responses to Ct antigens Pgp3 and CT694 are sensitive and specific markers of Ct infection. 14,15 Assays have demonstrated consistency across platforms (multiplex bead, enzyme-linked immunosorbent, lateral flow), 16,17 robust seropositivity cutoffs, 18 and high repeatability.…”