Abstract
Dengue has become endemic in Pakistan with annual recurrence. A sudden increase in the dengue cases was reported from Rawalpindi in 2016, while an outbreak occurred for the first time in Peshawar in 2017. Therefore, a multi-center study was carried out to determine the circulating dengue virus (DENV) serotypes and Chikungunya virus (CHIKV) co-infection in Lahore, Rawalpindi, and Peshawar cities in 2016–18. A hospital-based cross-sectional study was carried out in Lahore and Rawalpindi in 2016–18, while a community-based study was carried out in Peshawar in 2017. The study participants were tested for dengue NS1 antigen using an immunochromatographic device while anti-dengue IgM/IgG antibodies were detected by indirect ELISA. All NS1 positive samples were used for DENV serotyping using multiplex real-time PCR assay. Additionally, dengue samples were tested for CHIKV co-infection using IgM/IgG ELISA. A total of 6291 samples were collected among which 8.11% were NS1 positive while 2.5% were PCR positive. DENV-2 was the most common serotype (75.5%) detected, followed by DENV-1 in 16.1%, DENV-3 in 3.9% and DENV-4 in 0.7% while DENV-1 and DENV-4 concurrent infections were detected in 3.9% samples. DENV-1 was the predominant serotype (62.5%) detected from Lahore and Rawalpindi, while DENV-2 was the only serotype detected from Peshawar. Comorbidities resulted in a significant increase (p-value<0.001) in the duration of hospital stay of the patients. Type 2 diabetes mellitus substantially (p-value = 0.004) contributed to the severity of the disease. Among a total of 590 dengue positive samples, 11.8% were also positive for CHIKV co-infection. Co-circulation of multiple DENV serotypes and CHIKV infection in Pakistan is a worrisome situation demanding the urgent attention of the public health experts to strengthen vector surveillance.
Highlights
Dengue is caused by a positive-sense single-stranded RNA virus known as dengue virus (DENV) belonging to the family Flaviviridae genus Flavivirus
Dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) is the most serious manifestation of dengue fever characterized by thrombocytopenia, hemorrhagic manifestations, vascular leakage, hypotension, and shock which might lead to organ failure and death [24]
The co-circulation of all four DENV serotypes in the major metropolitan cities (Lahore and Rawalpindi) of Punjab is a worrisome situation as it could result in an outbreak of dengue hemorrhagic fever (DHF)/DSS in the future
Summary
Dengue is caused by a positive-sense single-stranded RNA virus known as dengue virus (DENV) belonging to the family Flaviviridae genus Flavivirus. The virus has four antigenically distinct serotypes (DENV-1 to 4) [1], which are maintained in a human-to-mosquito-tohuman transmission cycle [2]. In addition to these previously known four serotypes, a fifth serotype, DENV-5, circulating in the macaques has been proposed from Malaysia in 2013 [3]. Because of the subtropical location of Pakistan, it is the hotspot for many vector-borne diseases like dengue, malaria, leishmaniasis, West Nile virus, and Crimean-Congo hemorrhagic fever, etc. Ae. albopictus mosquitoes were collected from Changa Manga National Forest near Lahore in 1964 [9]. Serosurveys carried out in 1983/ 1985 in Karachi detected antibodies against DENV-2 in the healthy population [11]
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