Comparison of clinical presentation and out-comes of Chikungunya and Dengue virus infections in patients with acute undifferentiated febrile illness from the Sindh region of Pakistan.

Author summary Chikungunya and Dengue viral infection are prevalent in South Asia. These are spread by mosquito bites and present as acute febrile illness with clinical presentation difficult to differentiate. In this study we analysed clinical findings of patients with lab confirmed Dengue virus and Chikungunya virus infection and compared the clinical symptoms to assess significant features that can differentiate the two infections at time of presentation to clinics and hospitals. The study was conducted at the Aga Khan University Hospital, Karachi Pakistan. Our study confirms presence of Chikungunya virus as an etiologic agent of fever among patients with dengue like illness in Sindh province of Pakistan. Presence of joint pains, central nervous symptoms were more common in CHKV patients, while gastrointestinal symptoms and elevated liver enzymes were more commonly associated with dengue patients. Both viruses are endemic in Pakistan and clinical and lab diagnosis is essential. Background Arboviruses are a cause of acute febrile illness and outbreaks worldwide. Recent outbreaks of Chikungunya virus (CHIKV) in dengue endemic areas have alarmed clinicians as unique clinical features differentiating CHIKV from Dengue virus (DENV) are limited. This has complicated diagnostic efforts especially in resource limited countries where lab testing is not easily available. Therefore, it is essential to analyse and compare clinical features of laboratory confirmed cases to assist clinicians in suspecting possible CHIKV infection at time of clinical presentation. Methodology A prospective point prevalence study was conducted, with the hypothesis that not all patients presenting with clinical suspicion of dengue infections at local hospitals are suffering from dengue and that other arboviruses such as Chikungunya, West Nile viruses, Japanese Encephalitis virus and Zika virus are co-circulating in the Sindh region of Pakistan. Out-patients and hospitalized (in-patients) of selected district hospitals in different parts of Sindh province of Pakistan were recruited. Patients with presumptive dengue like illness (Syndromic diagnosis) by the treating physicians were enrolled between 2015 and 2017. Current study is a subset of larger study mentioned above. Here-in we compared laboratory confirmed cases of CHIKV and DENV to assess clinical features and laboratory findings that may help differentiate CHIKV from DENV infection at the time of clinical presentation. Results Ninety-eight (n = 98) cases tested positive for CHIKV, by IgM and PCR and these were selected for comparative analysis with DENV confirmed cases (n = 171). On multivariable analysis, presence of musculoskeletal [OR = 2.5 (95% CI:1.6-4.0)] and neurological symptoms [OR = 4.4 (95% CI:1.9-10.2)], and thrombocytosis [OR = 2.2 (95% CI:1.1-4.0)] were associated with CHIKV infection, while atypical lymphocytes [OR = 8.3 (95% CI:4.2-16.7)] and thrombocytopenia [OR = 8.1 (95% CI:1.7-38.8)] were associated with DENV cases at time of presentation. These findings may help clinicians in differentiating CHIKV from DENV infection. Conclusion CHIKV is an important cause of illness amongst patients presenting with acute febrile illness in Sindh region of Pakistan. Arthralgia and encephalitis at time of presentation among patients with dengue-like illness should prompt suspicion of CHIKV infection, and laboratory confirmation must be sought.