Fatal Case of Diphtheria and Risk for Reemergence, Singapore

Clinical presentation and predictors of hospital mortality of diphtheria in Nigeria, July 2023 to April 2024: a single-center study

BACKGROUND

Despite recurrent outbreaks of diphtheria in Nigeria, there is a lack of in-depth analysis of hospitalization outcomes. Herein, we describe the sociodemographic, clinical, and laboratory features associated with hospitalization outcomes (defined as death or discharge) during the recent diphtheria outbreak in Nigeria.

METHODS

This prospective observational study included 246 confirmed diphtheria cases managed in a dedicated isolation ward of a health facility in northwestern Nigeria from July 1, 2023, to April 30, 2024. We analyzed clinical and laboratory features, immunization status, and socio-demographics in relation to hospitalization deaths using SPSS version 29.

RESULTS

The median age (interquartile range) was 7.00 (4-10) years and 49.6% (122) were aged 5-10 years. Common clinical features were fever (95.9%), sore throat (91.9%), painful swallowing (90.7%), pseudomembrane (93.1%), and cervical-submandibular lymphadenopathy (91.5%). Most children were unvaccinated (158; 64.2%), 199 (80.9%) received diphtheria antitoxin, and both were related to outcomes. Mortality rate was 23.5% (58/246). After adjusting for confounders, predictors of hospitalization deaths were neck swelling with an adjusted odds ratio (AOR) of 9.80 (95% CI 1.68-56.47), abnormal respiratory findings (AOR, 149.99 [95% CI, 15.60-1442.02] ), hypoxemia (AOR, 37.79 [95% CI, 4.26-331.96] ), and elevated serum creatinine above 1.5 mg/dL (AOR 107.78, 95% CI, 7.94-1462.38).

CONCLUSIONS

Diphtheria is a significant burden in Nigeria, particularly among children. Neck swelling, hypoxemia, abnormal respiratory findings, and impaired renal function were predictive of hospitalization death. Although antitoxin and vaccination were related to outcomes, they did not predict hospitalization death.

Eleven-Year Report of High Number of Diphtheria Cases in Children in East Java Province, Indonesia

A high incidence of diphtheria cases in children in East Java province, Indonesia, has been observed since the beginning of this century. Despite many efforts, the outbreaks continue. This study aims to explain the high incidence of diphtheria in children in East Java province since 2013. This cross-sectional surveillance report-based study used data from 38 districts in East Java since 1 January 2013. Collected data included demographics, clinical information, additional examinations, immunization history, and close contact management. Over eleven years, there were 4009 diphtheria patients, of whom 2921 (72.86%) were under 18 years of age. Boys (59.77%) outnumbered girls, and the most common age category was >60-144 months (51.66%). Most cases had incomplete or zero immunization (76.16%). Tonsillopharyngeal diphtheria was the most common type (69.60%). The five top districts with the most cases were Surabaya, Sidoarjo, Kabupaten Blitar, Kota Malang, and Kabupaten Malang. The eleven-year case fatality rate (CFR) was 2.36% (69/2921). This study shows that diphtheria cases in children and adolescents in East Java have consistently been high, and low immunization coverage might still be the leading cause. There has also been a shift in the district distribution. Diphtheria outbreaks require complete and sustainable efforts, not just outbreak response immunizations.

Interactions between the Re-Emerging Pathogen Corynebacterium diphtheriae and Host Cells

Corynebacterium diphtheriae, the etiological agent of diphtheria, is a re-emerging pathogen, responsible for several thousand deaths per year. In addition to diphtheria, systemic infections, often by non-toxigenic strains, are increasingly observed. This indicates that besides the well-studied and highly potent diphtheria toxin, various other virulence factors may influence the progression of the infection. This review focuses on the known components of C. diphtheriae responsible for adhesion, invasion, inflammation, and cell death, as well as on the cellular signaling pathways activated upon infection.

Seroprevalence of IgG antibodies against diphtheria antitoxin among migrant workers in Singapore, 2016-2019

Background

Since the last local case of diphtheria in 1992, there had not been any case in Singapore until an autochthonous case was reported in 2017. This fatal diphtheria case of a migrant worker raised concerns about the potential re-emergence of locally transmitted toxigenic diphtheria in Singapore. We conducted a seroprevalence study to assess the immunity levels to diphtheria among migrant workers in Singapore.

Methods

Residual sera from migrant workers who hailed from Bangladesh, China, India, Indonesia, Malaysia, Myanmar and the Philippines were tested for anti-diphtheria toxoid immunoglobulin G (IgG) antibodies. These migrant workers previously participated in a survey between 2016 and 2019 and had provided blood samples as part of the survey procedure.

Results

A total of 2176 migrant workers were included in the study. Their overall mean age was 27.1 years (standard deviation 5.0), range was 20–43 years. The proportion having at least basic protection against diphtheria (antitoxin titres ≥ 0.01 IU/ml) ranged from 77.9% (95% confidence interval [CI] 72.8 – 82.3%) among migrant workers from Bangladesh to 96.7% (95% CI 92.5 – 98.6%) in those hailing from Malaysia. The proportion showing full protection (antitoxin titres ≥ 0.10 IU/ml) ranged from 10.1% (95% CI 6.5 – 15.4%) in Chinese workers to 23.0% (95% CI 17.1 – 30.3%) in Malaysian workers. There were no significant differences in the proportion with at least basic protection across birth cohorts, except for those from Bangladesh where the seroprevalence was significantly lower in younger migrant workers born after 1989.

Conclusions

The proportions having at least basic protection against diphtheria in migrant workers from five out of seven Asian countries (India, Indonesia, Malaysia, Myanmar and the Philippines) were higher than 85%, the threshold for diphtheria herd immunity. Seroprevalence surveys should be conducted periodically to assess the level of immunity against diphtheria and other vaccine preventable diseases in migrant worker population, so that appropriate interventions such as booster vaccination can be implemented proactively to prevent sporadic outbreaks.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-12528-y.

First-line antibiotic susceptibility pattern of toxigenic Corynebacterium diphtheriae in Indonesia

BACKGROUND

Diphtheria has been reported as an outbreak in some regions in Indonesia, most especially in East Java Province. Resistance to penicillin, erythromycin, and other antibiotics, single or multiple, has been reported in several studies. This study aims to evaluate the first-line antibiotic susceptibility pattern of toxigenic Corynebacterium diphtheriae isolates.

METHODS

This descriptive observational study was performed from August to November 2018. C. diphtheriae isolates were collected from diphtheria patients and carriers in East Java from 2012 to 2017 and kept at the Balai Besar Laboratorium Kesehatan Daerah Surabaya or the Public Health Laboratory of Surabaya. Sample selection was done by random cluster sampling. The sensitivity test by E-test®of the five antibiotics (penicillin, oxacillin, erythromycin, azithromycin, and clarithromycin) was done to determine the minimum inhibitory concentration (MIC). The Clinical and Laboratory Standards Institute M45A (2015) Corynebacterium spp. for penicillin and erythromycin was used as standard.

RESULTS

From 114 targeted isolates, 108 were viable and toxigenic. The E-test was performed on the viable isolates. The majority of the hosts were male (58.3%), with median (range) age of 6.5 (1-14) years. Half of the samples were from the 1 to 5-year-old age group. The isolates were acquired much more from patients (78.7%) than carriers (21.3%) and from pharyngeal swab (74.1%). Most of these isolates were from Madura Island (47.2%) and the northern and eastern parts of the province (horseshoe area). Mitis isolates were the major variant (76.9%). The susceptibility pattern of C. diphtheriae to erythromycin was better than that to penicillin. The E-test result for penicillin was 68.52% susceptible, 31.48% intermediate, and 0% resistant (MIC range, < 0.016 to 2 μg/L) and for erythromycin (MIC range, < 0.016 to > 256 μg/L) was 85.2% susceptible, 12% intermediate, and 2.8% resistant The MIC range for oxacillin was 1 to 96 μg/L, while for both azithromycin and clarithromycin were <  0.016 to > 256 μg/L.

CONCLUSION

The susceptibility rate of C. diphtheriae to erythromycin is higher than that to penicillin. The regular update of antibiotic selection to the national guidelines is recommended. The MIC reference standard to azithromycin and clarithromycin is also needed.

Are migrant workers in Singapore receiving adequate healthcare? A survey of doctors working in public tertiary healthcare institutions

INTRODUCTION

Migrant workers comprise about one-fifth of Singapore's resident population and form a substantial and vital component of the nation's workforce. However, limited data is available regarding the barriers that migrant workers face in accessing healthcare from the healthcare providers' perspective.

METHODS

We conducted a survey on doctors working in four restructured hospitals in Singapore, to assess what they perceived to be barriers faced by migrant workers in accessing healthcare. We also assessed the doctors' understanding of migrant-health-related policies in Singapore.

RESULTS

A total of 427 survey responses were collected. Most respondents were senior doctors (senior residents or consultants) who had been practising medicine for a median of ten years. Among doctors, the most common perceived barriers to migrant workers accessing healthcare were related to culture/language (92.3%) and finances (healthcare cost) (81.0%). Of the six questions asked pertaining to migrant healthcare policy in Singapore, the respondents achieved a median of four correctly answered questions (interquartile range 3-5), and about 55% were unaware or unsure of available resources for migrant workers.

CONCLUSION

Our study identified healthcare providers' perceived barriers to the delivery of healthcare to migrant workers, which corroborate previously published data reported by migrant workers themselves. Further efforts should be directed towards diminishing these barriers and increasing the literacy of migrant health among healthcare workers.