Introduction

Statics of typhoid infection worldwide and Cameroon

Vaccine situation

Diagnostics method available

Serological testing

The diagnostics used to detect enteric fever are mostly serological testing, globally. Serological testing has been more widely used than nucleic acid testing due to the simplicity and cost in the resources needed for testing while compared to NAT which require laboratory facility. The Widal test being the most popular method  . Blood samples most popularly used for  diagnosis and stool samples are recommended to be avoided due to asymptomatic faecal shedding following the infection. There are commercially available rapid serological tests like Typhidot (Malaysian Bioduagnostic Research Sdn Bhdd, KL, Malaysia) that detects the antibody against the S.typhi outer-membrane protein, Tubex TF (IDL Biotech, Sollentuna, Sweden) detects antibody against LPS an.­­­­-­­­­­­

Nucleic acid testing

NAT tests that are developed are mostly conventional PCR and LAMP have been demonstrated to have specificity of .  the Merieux foundation is validated a NAT  in Bangladesh and currently in progress in Democratic Republic of the Congo, Burkina Faso, Malawi and Ghana.

Challenges in typhoid diagnostics

Serological testing  globally has been shown to have poor sensitivity and inadequate specificity. WIDAL test has been also demonstrated to be an due to (a) cross-reactivity with antibody from many other infections (b) establishing a baseline in the population where the infection is endemic and actively vaccinated (A and L, 2000). A recent stakeholders engagement summarized that the current challenges in diagnostics needs to improve the sensitivity of the tests to >90% and specificity >95% (Richard et al., 2019) 
Add WHO guidelines 

AMR

Use Minette’s review
 
Path forward with multiplexing

CRISPR Scissors for molecular detection

First demonstration of the ability of Cas13a  to cleave non-targeted RNA after  cleaving the targeted RNA template \cite{East_Seletsky_2016}.    platform like Cas12-DETECTR \cite{Chen_2018}, Cas14-DETECTR , Cas13-SHERLOCK While Cas13a  recognizes  RNA as a template strand, Cas14 recognizes ssDNA and Cas12  recognizes ds/ss DNA. . The choice of any these molecular scissors depends on the needs of the end product.  CRISPR-Cas technique has now widely used to detect human papillomavirus (Chen et al., 2018), ZIKA and also the 2020 pandemic Sars-CoV-2.