The increase in occurrence of typhoid fever in Cameroon: overdiagnosis due to misuse of the Widal test?

Clinical characteristics of enteric fever and performance of TUBEX TF IgM test in Indonesian hospitals

BACKGROUND

Accurate diagnosis of enteric fever is challenging, particularly in low- and middle-income countries, due to the overlap of clinical and laboratory features with other pathogens. To better understand the difficulties in enteric fever diagnosis, we evaluated the characteristics of patients clinically diagnosed with enteric fever and the real-world performance of TUBEX TF, one of the most used tests in Indonesia.

METHODOLOGY/PRINCIPAL FINDINGS

Patients were recruited through the AFIRE (Etiology of Acute Febrile Illness Requiring Hospitalization) study at eight Indonesian hospitals. Blood culture was performed for all patients, and TUBEX TF was performed for suspected enteric cases. Salmonella PCR and ELISA tests were performed at a reference lab. Sensitivity and specificity of TUBEX TF and IgM and IgG anti-S. Typhi ELISA were determined. Of 301 patients clinically diagnosed with enteric fever, 50 (16.6%) were confirmed by blood culture and/or PCR. Confirmed cases were mostly school-aged children presenting with fever, anorexia, dizziness and/or abdominal pain with normal leukocyte count or leukopenia. TUBEX TF demonstrated a sensitivity of 97.6% to 70.7% and specificity of 38.3% to 67.2% at cutoffs of 4 and 6, respectively. Acute IgG demonstrated the best sensitivity and specificity, at 90.7% and 82.7%, respectively, and the best ROC characteristics.

CONCLUSIONS/SIGNIFICANCE

A substantial proportion of enteric fever was misdiagnosed at all study hospitals, likely due to the overlap of clinical characteristics and lab parameters with those of other common pathogens. The TUBEX TF rapid serological assay demonstrated suboptimal performance in our setting and tended to over-diagnose enteric fever. The role of IgG from acute specimens for identification of enteric fever cases merits additional consideration.

Rapid stool antigenic test for typhoid fever among suspected cases, Northeast, Ethiopia

Typhoid fever continued to be the key cause of morbidity and mortality in developing countries with poor hygienic practices and limited access to safe drinking water. The Widal card agglutination test is the main diagnostic tool in Ethiopia, which is limited in differentiating the overlapping symptoms with other acute febrile illnesses such as malaria and viral enteritis. This eventually leds to unnecessary antibiotic use and eventual drug resistance. Therefore this study wants to assess the burden and associated potential risk factors of typhoid fever among suspected cases using the typhoid rapid stool antigen test in Northeast Ethiopia. A hospital-based cross-sectional study was conducted at Gaint and Meket Shediho primary hospitals from May to July 2021. A total of 255 patients clinically suspected of typhoid fever, and willing to grant informed consent were included systematically. The demographic and hygiene-related variables were collected using a pre-tested structured questionnaire. The rapid stool antigenic test and xylose-lysine-deoxycholate agar (XLD) stool culture were evaluated for the level of agreement. The present study indicated that the prevalence of typhoid fever was 15.3%. This displayed that the human-restricted infectious disease, typhoid fever remained a challenge to Ethiopians. Washing hands with soap, history of typhoid fever, having previous history of hospitalization, and chronic underlying disease was the significant potential factor for typhoid fever. The higher agreement of the rapid stool antigenic test with the stool culture can indicate the factual burden of typhoid fever in the suspected population. This could minimize empiric treatment and the possible emergence of drug resistance. Thus, resource-poor settings may need to look for a rapid and reliable stool antigenic test.

Debunking highly prevalent health misinformation using audio dramas delivered by WhatsApp: evidence from a randomised controlled trial in Sierra Leone

Introduction

Infectious disease misinformation is widespread and poses challenges to disease control. There is limited evidence on how to effectively counter health misinformation in a community setting, particularly in low-income regions, and unsettled scientific debate about whether misinformation should be directly discussed and debunked, or implicitly countered by providing scientifically correct information.

Methods

The Contagious Misinformation Trial developed and tested interventions designed to counter highly prevalent infectious disease misinformation in Sierra Leone, namely the beliefs that (1) mosquitoes cause typhoid and (2) typhoid co-occurs with malaria. The information intervention for group A (n=246) explicitly discussed misinformation and explained why it was incorrect and then provided the scientifically correct information. The intervention for group B (n=245) only focused on providing correct information, without directly discussing related misinformation. Both interventions were delivered via audio dramas on WhatsApp that incorporated local cultural understandings of typhoid. Participants were randomised 1:1:1 to the intervention groups or the control group (n=245), who received two episodes about breast feeding.

Results

At baseline 51% believed that typhoid is caused by mosquitoes and 59% believed that typhoid and malaria always co-occur. The endline survey was completed by 91% of participants. Results from the intention-to-treat, per-protocol and as-treated analyses show that both interventions substantially reduced belief in misinformation compared with the control group. Estimates from these analyses, as well as an exploratory dose–response analysis, suggest that direct debunking may be more effective at countering misinformation. Both interventions improved people’s knowledge and self-reported behaviour around typhoid risk reduction, and yielded self-reported increases in an important preventive method, drinking treated water.

Conclusion

These results from a field experiment in a community setting show that highly prevalent health misinformation can be countered, and that direct, detailed debunking may be most effective.

Trial registration number

NCT04112680.

Trends of potential waterborne diseases at different health facilities in Bamboutos Division, West Region, Cameroon: a retrospective appraisal of routine data from 2013 to 2017

Many Cameroonian cities lack access to potable drinking water where populations rely on alternative water sources of doubtful quality. This study aimed at describing the trends and patterns of waterborne diseases (WBDs) reported in some health facilities in Bamboutos Division between 2013 and 2017 as baseline data towards understanding the profile of WBDs in this area. A retrospective review of clinical data kept on patients who visited the main health facilities in Bamboutos Division from January 2013 to December 2017 was conducted. Overall, 39.1% (n = 8,124) of total patients were positive for at least one WBD. Categories of WBDs were dysenteries (18.6%), gastroenteritis (4.2%), viral hepatitis (0.2%) and typhoid was the most preponderant (24.4%). The most affected age groups were those above 24 years but significant differences were observed only in 2013 and 2017. Distribution of potential WBDs was locality dependent. The highest prevalence of typhoid fever was recorded in Bameboro (35.4%), dysenteries in Bamedjinda (20.4%) and gastroenteritis (17.3%) in Bamekoumbou. The study shows very high overall prevalence of WBDs in some localities which could be considered as 'hotspots' of WBDs in Bamboutos. This suggests the urgent need for setting up measures to tackle the challenges of potable drinking water supply.

Bacteremia Among Febrile Patients Attending Selected Healthcare Facilities in Ibadan, Nigeria

BACKGROUND

The relative contribution of bacterial infections to febrile disease is poorly understood in many African countries due to diagnostic limitations. This study screened pediatric and adult patients attending 4 healthcare facilities in Ibadan, Nigeria, for bacteremia and malaria parasitemia.

METHODS

Febrile patients underwent clinical diagnosis, malaria parasite testing, and blood culture. Bacteria from positive blood cultures were isolated and speciated using biochemical and serological methods, and Salmonella subtyping was performed by polymerase chain reaction. Antimicrobial susceptibility was tested by disk diffusion.

RESULTS

A total of 682 patients were recruited between 16 June and 16 October 2017; 467 (68.5%) were <18 years of age. Bacterial pathogens were cultured from the blood of 117 (17.2%) patients, with Staphylococcus aureus (69 [59.0%]) and Salmonella enterica (34 [29.1%]) being the most common species recovered. Twenty-seven (79.4%) of the Salmonella isolates were serovar Typhi and the other 7 belonged to nontyphoidal Salmonella serovarieties. Thirty-four individuals were found to be coinfected with Plasmodium falciparum and bacteria. Five (14.7%) of these coinfections were with Salmonella, all in children aged <5 years. Antimicrobial susceptibility testing revealed that most of the Salmonella and Staphylococcus isolates were multidrug resistant.

CONCLUSIONS

The study demonstrates that bacteria were commonly recovered from febrile patients with or without malaria in this location. Focused and extended epidemiological studies are needed for the introduction of typhoid conjugate vaccines that have the potential to prevent a major cause of severe community-acquired febrile diseases in our locality.

Seroprevalence of dengue virus among children presenting with febrile illness in some public health facilities in Cameroon

INTRODUCTION

A routine diagnosis of Dengue virus (DENV) infection is not usually conducted in hospitals. Because symptoms overlap, many potential febrile illnesses due to DENV may be confused for malaria, typhoid or paratyphoid (enteric) fever. The absence of data on DENV exposure rates among children attending health facilities could undermine management of this disease. This study aimed to investigate the seroprevalence of dengue virus infection in children presenting febrile illness in some public health facilities in Cameroon.

METHODS

A cross-sectional study was performed in children ≤ 15 years attending seven urban and three semi-urban public hospitals of Cameroon. From each volunteer, 2ml of whole blood was collected and tested for dengue virus IgM, malaria (Pf/Pan antigens) and enteric fever (Typhoid IgM) using rapid diagnostic tests (RDT); in order to allow the healthcare workers to quickly put the positive cases under appropriate treatment. Positive cases of dengue virus infection were confirmed by indirect ELISA. Data analysis were performed using the statistical package for social sciences software, version 22.1.

RESULTS

A total of 961 children were enrolled in the study and 492 (51.2%) were infected with at least one of the three pathogens. Overall, DENV IgM seroprevalence among febrile children was 14.4% (138/961). About 390 (40.6%) and 22 (2.3%) had malaria (Pf/Pan Ag) and enteric fever (Typhoid IgM) respectively. Co-infection with dengue virus was found in 51 (5.3%) participants. The dengue virus IgM seroprevalence was higher in Bankim (19.3%), Ntui (18.3%) and Douala (18.2%).

CONCLUSION

Dengue virus infection seroprevalence appears to be low in children presenting with febrile illness in the studied health centres in Cameroon but call for more attention and research to further characterise the circulating strains of the dengue virus.

Implementation of Interventions for the Control of Typhoid Fever in Low- and Middle-Income Countries

Past research has focused on typhoid fever surveillance with little attention to implementation methods or effectiveness of control interventions. This study purposefully sampled key informants working in public health in Chile, India, Pakistan, Bangladesh, Thailand, Vietnam, South Africa, and Nigeria to 1) scope typhoid-relevant interventions implemented between 1990 and 2015 and 2) explore contextual factors perceived to be associated with their implementation, based on the Consolidated Framework for Implementation Research (CFIR). We used a mixed methods design and collected quantitative data (CFIR questionnaire) and qualitative data (interviews with 34 public health experts). Interview data were analyzed using a deductive qualitative content analysis and summary descriptive statistics are provided for the CFIR data. Despite relatively few typhoid-specific interventions reportedly implemented in these countries, interventions for diarrheal disease control and regulations for food safety and food handlers were common. Most countries implemented agricultural and sewage treatment practices, yet few addressed the control of antibiotic medication. Several contextual factors were perceived to have influenced the implementation of typhoid interventions, either as enablers (e.g., economic development) or barriers (e.g., limited resources and habitual behaviors). Consolidated Framework for Implementation Research factors rated as important in the implementation of typhoid interventions were remarkably consistent across countries. The findings provide a snapshot of typhoid-relevant interventions implemented over 25 years and highlight factors associated with implementation success from the perspective of a sample of key informants. These findings can inform systematic investigations of the implementation of typhoid control interventions and contribute to a better understanding of the direct effects of implementation efforts.

A comparative study of Widal test with blood culture in the diagnosis of typhoid fever in febrile patients

Background

Typhoid fever is a major health problem in developing countries and its diagnosis on clinical ground is difficult. Diagnosis in developing countries including Ethiopia is mostly done by Widal test. However, the value of the test has been debated. Hence, evaluating the result of this test is necessary for correct interpretation of the result. The main aim of this study was to compare the result of Widal test and blood culture in the diagnosis of typhoid fever in febrile patients.

Methods

Blood samples were collected from 270 febrile patients with symptoms clinically similar to typhoid fever and visiting St. Paul’s General Specialized Hospitals from mid December 2010 to March 2011. Blood culture was used to isolate S.typhi and S.paratyphi. Slide agglutination test and tube agglutination tests were used for the determination of antibody titer. An antibody titer of ≥1:80 for anti TO and ≥1:160 for anti TH were taken as a cut of value to indicate recent infection of typhoid fever.

Results

One hundred and eighty six (68.9%) participants were females and eighty four (31.1%) were males. 7 (2.6%) cases of S. typhi and 4 (1.5%) cases of S. paratyphi were identified with the total prevalence of typhoid fever 4.1%. The total number of patients who have indicative of recent infection by either of O and H antigens Widal test is 88 (32.6%). The sensitivity, specificity, Positive predictive Value and Negative predictive Value of Widal test were 71.4%, 68.44%, 5.7% and 98.9% respectively.

Conclusions

Widal test has a low sensitivity, specificity and PPV, but it has good NPV which indicates that negative Widal test result have a good indication for the absence of the disease.

The TUBEX test detects not only typhoid-specific antibodies but also soluble antigens and whole bacteria

TUBEX (IDL Biotech) is a 5 min semiquantitative colorimetric test for typhoid fever, a widely endemic disease. TUBEX detects anti-Salmonella O9 antibodies from a patient's serum by the ability of these antibodies to inhibit the binding between an indicator antibody-bound particle and a magnetic antigen-bound particle. Herein, we report that TUBEX could also be used to specifically detect soluble O9 lipopolysaccharide in antigen-spiked buffer by the ability of the antigen to inhibit the same binding between the particles. Sensitivity of antigen detection was improved (8-31 mug ml(-1)) by using a modified protocol in which the test sample was mixed with the indicator particles first, rather than with the magnetic particles as for antibody detection. The antigen was also detectable in spiked serum and urine samples, albeit less well (2-4-fold) than in buffer generally. However, no antigen was detected from six typhoid sera examined, all of which had anti-O9 antibodies. In addition, whole organisms of Salmonella Typhi (15 strains) and Salmonella Enteritidis (6 strains) (both O9(+) Salmonella), grown in simulated blood broths or on MacConkey agar, were also detectable by TUBEX when suspended at >9 x 10(8) organisms ml(-1). Expectedly, Salmonella Paratyphi A (7 strains), Salmonella Typhimurium (1 strain) and Escherichia coli (2 strains) were negative in the test. Thus, the same TUBEX kit may be used in several ways both serologically and microbiologically for the rapid diagnosis of typhoid fever. However, validation of the newer applications will require the systematic examination of real patient and laboratory materials.

Laboratory medicine in Africa: a barrier to effective health care

Providing health care in sub-Saharan Africa is a complex problem. Recent reports call for more resources to assist in the prevention and treatment of infectious diseases that affect this population, but policy makers, clinicians, and the public frequently fail to understand that diagnosis is essential to the prevention and treatment of disease. Access to reliable diagnostic testing is severely limited in this region, and misdiagnosis commonly occurs. Understandably, allocation of resources to diagnostic laboratory testing has not been a priority for resource-limited health care systems, but unreliable and inaccurate laboratory diagnostic testing leads to unnecessary expenditures in a region already plagued by resource shortages, promotes the perception that laboratory testing is unhelpful, and compromises patient care. We explore the barriers to implementing consistent testing within this region and illustrate the need for a more comprehensive approach to the diagnosis of infectious diseases, with an emphasis on making laboratory testing a higher priority.