# Dengue and Flavivirus Co-Infections: Challenges in Diagnosis, Treatment, and Disease Management
## 5 Implications of Better Understanding Flaviviral Co-Infections
### Better Disease Diagnosis
Consequently, it delays the disease management and treatment, which is pivotal to reduce the occurrence of severe complications, including haemorrhages, acute respiratory distress syndrome (ARDS), renal failure, and arthritis [82]. The relationship between DENV serotype and disease severity has been demonstrated, for example, the likelihood of developing DHF and SD is purportedly higher in patients infected with DENV-1 than DENV-2 or DENV-3 [83]. In addition, although less pronounced, DENV-1 infection is also linked to the occurrence of conjunctivitis, whilst the symptom is less commonly observed in DENV-2 cases. DENV-2-infected patients, on the other hand, are prone to experiencing joint pain and low platelet counts [83]. Additionally, the adjusted risk ratio (ARR) for dengue with warning signs is 5.94 times higher in DENV-2 infection than that of DENV-1 [76]. Comparing DENV-1 and DENV-4, DENV-1 serotype is more likely to cause hemorrhage, epigastralgia, neuroinvolvement, and thrombocytopenia in patients [84]. DENV-3 and DENV-4 are less commonly linked to severe outcomes even \begin{table}
\begin{tabular}{l l l l} \hline \hline
**Assay Type** & **Sensitivity Range** & **Specificity Range** & **Key Limitations** \\ \hline NS1 ELISA & 34–76\% & 95–100\% & Low for DENV-2 and secondary DENV infections. \\ \hline NS1 RDT & 37.8–80\% & 85–98\% & Cross-reactivity at high viral loads. \\ \hline NS1 + IgM & 90.3\% & 96.2\% & Optimal for acute-phase diagnosis. \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Diagnostic performance of NS1-based assays: sensitivity, specificity, and limitations. amid the predominance of DENV-4 [85]. The discrepancies in the clinical manifestations and disease severity caused by the DENV serotypes highlight the importance of identifying the infecting DENV serotype so patients can receive timely treatments; in terms of long-term management and follow-up care, emphasis can be given to the possible post-dengue complications that influence the patient's wellbeing [86]. In Zika, the disease complications primarily affect the CNS, which then leads to Guillain-Barre syndrome (GBS). The association of GBS with Zika was first reported in French Polynesia, in which 98% and 100% of GBS patients had anti-Zika IgM and neutralizing IgG antibodies, respectively [87]. The presence of anti-Zika IgM during the convalescence phase enables an early diagnosis 6 days from the symptom onset. However, given the cross-reactivity of the antibodies with other flaviviruses, the test result has to be interpreted alongside that of a plaque reduction neutralization test (PRNT) and an antibody-based diagnosis [88]. PRNT enhances the sensitivity and specificity of Zika diagnosis to 96.8% and 95.0%, respectively, enabling the differentiation of Zika and its fraternity [89]. Nonetheless, PRNT is not without limitations, its labor-intensive process, high costs, and need for specialized facilities, deter the rapid diagnosis [90,91]. To address the challenges posed by traditional diagnostics especially in minimizing contamination and shortening result turnarounds, automated assays for disease detection, including dengue, have been implemented. These systems are more sensitive and specific than the manual methods because they reduce human errors and comply with the standard procedures. At present, some automated assays allow multiplex diagnosis up to 19 pathogens concurrently [72]. For instance, the VITROS automated test can reach 100% accuracy in estimating viral loads [92]. This can tremendously overcome the relatively low result accuracy in rapid tests [93]. In the context of co-infection, [PERSON] et al. [94] developed a multiplex real-time reverse transcriptase PCR assay to detect and identify eight major flaviviruses in mosquitoes using TaqMan fluorogenic probes. [PERSON] et al. [95] combined specific probes and primers for DENV, ZIKV and CHIKV, allowing differentiation of the three viruses. The test provided conclusive results in less than an hour. [PERSON] et al.