## 3 Technical and Pre-Analytical Considerations
Suspensions of norovirus-positive stool samples (n = 54) were applied to UNEXP discs; after two weeks of storage at room temperature on the UNEXP discs, all samples showed norovirus RT-qPCR positive. A subset of seven samples was stored for three months and found RT-qPCR positive. In addition, genotyping was successful in 76% (41/54) of the samples [44]. Further research on FTA(r) card and UNEXP cards for other AGE viruses and under different storage conditions and durations would therefore be desirable. Technically, a wide variety of molecular laboratory-developed tests (LDT) as well as commercial assays are available to detect AGE pathogens [45]. The Luminex GPP assay was one of the first syndromic assays for GI pathogens on the market. It is a truly laboratory-based workflow, as it requires separate nucleic acid extraction and (in previous versions) post-PCR processing steps. In a similar fashion, the Fast Track Diagnostics gastroenteris panel offers real-time PCR-based multiplex testing. These conventional multiplex panels allow for batch testing of up to 96 samples but require sophisticated technical equipment. These technical prerequisites obviously limit their application in remote and/or resource-limited regions. However, a recent study showed that the detection rate increased over conventional methods [12]. A real-time PCR system is not available in many tropical regions due to cost, lack of equipment, and high technical demand on the staff, and therefore, the data on the routine use of PCR for AGE diagnosis are limited [25]. Most studies evaluating AGEs in resource-limited settings with multiplex PCR transfer the stool samples to industrialized countries or occasionally to remote urban laboratories with sufficient infrastructure [30, 36, 46]. The majority of studies are epidemiological and address the question of detection of coinfection in AGE in specific regions. However, the question of the utility of multiplex diagnostics in the LMIC setting is unclear, and in particular, the frequent multiple pathogen detection complicates this circumstance by making treatment decisions difficult. It is conceivable that the possibility of differentiating between bacterial and viral pathogens may reduce the use of antibiotics. However, if multiple pathogens are detected without differentiation between infection and colonization, the opposite is also conceivable with increased costs due to antibiotic overuse and the development of antimicrobial resistance [29]. Likewise, the question of cost-effectiveness analysis of conventional multiplex PCR diagnostics for the detection of AGE in resource-limited settings is largely unanswered. For example, only a study conducted in India by [PERSON] et al. showed that similar test accuracy can be achieved at a lower cost using in-house designed multiplex PCR compared to commercially available real-time assay (FTD Viral Gastroenteritis kit) [35]. Technological advancements are cartridge-based syndromic panels, i.e., no separate nucleic acid extraction and amplification/detection steps are necessary. This approach allows for rapid and point of care testing independently from diagnostic laboratories. These panels display very fast turn-around and minimal hands-on time but require specialized equipment from the respective manufacturer [47]. Currently, the BioFire Film Array Gastrointestinal Panel and the QIAstat Gastrointestinal (GI) Panel are examples of commercially available cartridge-based assays (Table 2). Pre-analytical considerations should also include the panel composition and the epidemiology of the analyzed pathogens. Major viral targets included in AGE multiplex \begin{table}
\begin{tabular}{c c} \hline \hline
**Manufacturer** & **Gastrointestinal Panel** \\ \hline Biomerieux & FilmArray Gastrointestinal (GI) Panel \\ \hline Luminex & Verigene Enteric Pathogens Test \\ \hline Qiagen & QIAstat-Dx Gastrointestinal Panel \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Currently available cartridge-based commercial multiplex panels for AG pathogens.