Introduction
Dengue and Chikungunya fever are arboviral infections of global importance. Dengue virus belongs to family Flaviviridae and genus Flavivirus. It is a small enveloped RNA virus carrying a single stranded, positive sense RNA genome of 10.6 kb in length. Dengue virus exists as four serotypes (DENV 1-4). According to a recent study, patients having the Dengue and Chikungunya virus co-infection present with a high mortality rate when compared to mono-infection with these viruses1. The two diseases share a common mode of transmission and have common clinical presentation; hence Chikungunya is found reactive with Dengue viral infection. Data over Dengue and Chikungunya co infection in a particular region is imperative for providing assistance to clinicians while diagnosing the two infections. Statistics regarding the co infection will help the district health authorities in taking preventive and control measures.
The first documented case of Dengue and Chikungunya virus co infection in humans was reported as early as 1967. The two viruses were isolated from a patient seen in Vellore, South India. Dengue and Chikungunya viral infections have common clinical presentations including high grade fever, body pain, nausea, headache and rashes. In case of a mild infection, the viral load decreases in around 10 days and the symptoms subside since these are the self limiting infections.1
Chikungunya infection presents with severe joint pain as the most prominent feature and which sometimes can persist for a few months to a years.2 In addition to this a severe Chikungunya viral infection can cause neurological and altered optical manifestations. Chikungunya viral infection is usually nonfatal while Dengue fever may result in severe complications including death.3 The diagnosis and treatment of such patients becomes difficult since co infection with the two viruses may result in disease with overlapping symptoms. Timely diagnosis of the dual infections is important for better case management.
Limited investigations have studied the role of dual viral infections in clinical presentation of the disease. Dengue and Chikungunya co-infections are associated with more severe clinical disease than mono-infection.4 The requirement of mechanical ventilation and blood transfusion was found to be higher in the co-infected patients. A recent study reported the involvement of central nervous system and hemorrhagic manifestations in such cases.5, 6
The two different viruses cause dual infection of a mosquito vector by consecutive bites of two different infected human patients or by a single bite of a co-infected patient. Aedes albopictus has been shown to have the ability of getting orally co infected with Dengue and Chikungunya virus.7 A recent study reported that both Dengue and Chikungunya viruses were able to replicate simultaneously in the mosquito and have the ability to deliver concomitantly infectious particles of Dengue and Chikungunya virus in a single bite via saliva.8, 9
The present study included all suspected cases of Dengue and Chikungunya in and around Kalaburagi district reporting to Government General Hospital (GGH) Kalaburagi. The present study aimed at analysing the incidence and percentage prevalence of dengue mono infection and Dengue with Chikungunya seropositive cases reporting at Gulbarga General Hospital (GGH) in Kalaburagi district part of the Hyderabad Karnataka region of Karnataka, India.
Materials and Methods
Source of data
Patients reporting to Government General Hospital Kalaburagi, Karnataka from January 2019 to December 2019. Patients presenting with fever more than 38.5° Celcius and clinical features suggestive of Dengue and Chikungunya illness.
Study design
It is a cross sectional study through random sampling technique. A total of 5,134 patients suspected of Dengue and Chikungunya were admitted to the GGH, Kalaburagi between January 2019 to December 2019. Clinical features varied from fever, dysentery, rashes to myalgia headache and arthalgia. Patients were admitted and investigations were commenced to the earliest. Diagnosis of Dengue and Chikungunya were based on WHO criteria. The present study aims to describe the burden of Dengue and Chikungunya separately as well as the percentage of Dengue Chikungunya co infection cases in Kalaburagi district and elaborate the most important clinical features recorded.
Inclusion criteria
Study population was divided according to their geographical distribution. All the patients with clinical features suggestive of Dengue and Chikungunya infection and later confirmed by IgM ELISA were included in the study.
Exclusion criteria
Critically ill patients, patients with laboratory confirmed malaria, leptospirosis infection and enteric fever. Also patients with haematological disorders were excluded.
Investigations Included
Blood samples from clinically suspected cases of Dengue fever and Chikungunya fever attending various departments of GGH Kalaburagi, Karnataka were collected and screened at Central laboratory GGH. The samples were maintained in cold chain and sent to Viral Research and Diagnostic Laboratory (VRDL), Department of Microbiology, GIMS, Kalaburagi for serological confirmation. Once samples reached VRDL the serological confirmation was performed by Anti dengue IgM and Anti Chikungunya IgM kits, supplied by National Institute of Virology, Pune, Maharashtra, India. All steps were followed as per manufacturer’s instructions.
Results
The Dengue positive cases showed fever and myalgia as their primary symptoms followed by headache, chills and abdominal pain, whereas Chikungunya and Dengue with Chikungunya seropositive cases presented with fever with arthalgia and chills as their primary symptom followed by headache, vomiting and nausea (Figure 1). The study evaluated the clinical presentation and seroprevalance of Dengue and Chikungunya in the city of Kalaburagi. The study results are in unison with previous studies10, 6 with regards to clinical symptoms for each illness.
The numbers of cases were distributed on yearly and quarterly basis. All data collected were processed by frequency analysis, percentage, mean, paired t test. Total number of cases reported between January 2019 to December 2019 account to 5134 of which 207 were found positive (Figure 5) for Dengue with Chikungunya co infection. Dengue mono infection seropositive cases had 17.2% positivity as compared to 14% in 2018 and 8.9% in 2017 and Chikungunya monoinfection seropositive cases were found to be 11.5% positivity as compared to 9% in 2018 and 4.5% in 2017 (Figure 2). 26% positivity was found for Dengue with Chikungunya co infection for 2019, 17.5% for 2018 and 15% for 2017 (Figure 2). Average age distribution among all Dengue with Chikungunya co infection was 26 years and Male to Female ratio was found to be 1.1:1. 84% of Dengue positive cases reported to GGH were from Kalaburagi city main and later followed by nearby talukas like Sedam (1%) Jewargi (1%), Afzalpur (4%), Aland (3%), Chincholi (4%), Chitapur (3%) (Figure 6). Dengue with Chikungunya co infection cases, 88% reported from Kalaburagi city main, followed by Jewargi (2%), Sedam (2%), Chincholi (3%), Afzalpur (2%), Aland (2%), and Chitapur (1%) (Figure 7).
Discussion
Since the first reported case in 1967, India is endemic to Dengue and Chikungunya on every or alternate year. Although Chikungunya viral infection not uncommon experienced a decline in trend since the year 2010 until the recent outbreak in 2016. Increase in human population and urbanization has contributed to more collection of water in pots and unused tyres, water collection at construction sites and the poor drainage systems with lack of knowledge on prevention among the masses has given rise to increase in the mosquito population. In the midst of a conducive environment for growth Dengue and Chikungunya viral infections sharing a common vector Aedes albopictus cases of Dengue with Chikungunya co infection cannot be ignored. According to Centre for diseases control and prevention before treating a Chikungunya positive patient with Non steroidal anti inflammatory drugs one should rule out the dengue infection as these drugs can further complicate the illness. Similarly only treating a dengue fever case without ruling out Chikungunya involvement can lead to long term arthralgia and other joint related complications.11 Diagnosis of both the illness is widely performed by ELISA and is considered as one of the confirmatory tests. IgM capture ELISA has become popular due to reliable sensitivity and specificity. The present study found 17.2% positivity among the suspected cases of dengue and 10.9% positivity among the Chikungunya suspected cases in 2019. Dengue with Chikungunya co infection accounted to 26% cases which is higher as compared to previous year data at GIMS hospital, Kalaburagi. GIMS hospital Kalaburagi receives samples from neighbouring talukas namely Aland, Afzalpur, Chitapur, Chincholi, Sedam and Jewargi. With 5314 suspected cases reported this year Kalaburagi district experienced extended intermittent rains in the last quarter of the year 2019. This was a major reason for four outbreaks that occurred in the district of Kalaburagi.
Conclusion
In the past Dengue and Chikungunya were presumed to be associated in rainy season only. In recent times Chikungunya has emerged as an important public health concern in India.10 In the year 2016 more than 1.3 million people were severely affected by Chikungunya infection11 Both the viral infections need to be studied on the basis of seroprevalance to help predict the illness at the earliest. The present study gives data on the incidence and average age distribution and gender distribution as well as geographic spread of the disease in Kalaburagi district, Karnataka. Although both Dengue as well as Chikungunya is self limiting illness, the clinically suspected cases should be tested for both the pathogens in the endemic areas and knowledge about its clinical presentation and exact time for diagnosis will help in preventing complications and result in successful clinical management. Scope of diagnosing Dengue and its subtypes along with Chikungunya co infections through molecular tests like Polymerase Chain Reaction needs to be considered for better understanding and spread of the illness.
Unlike Dengue, Chikungunya typically consists of a self-limiting and nonfatal acute illness characterised by fever, rash and incapacitating arthralgia.12 Molecular techniques are promising and should be employed to rule out cases with cross reactivity. Further studies with molecular diagnosis based on Reverse transcriptase Real time Polymerase chain reaction on Serotyping and cross reactivity are required for better understanding of the co infection.
Acknowledgement
We would like to thank Dr Umesh SR Director GIMS, Kalaburagi for providing necessary infrastructure and facilities to conduct the study. We thank National Institute of Virology, Pune for providing ELISA test kits. This work was supported and funded by DHR-ICMR Govt of India under the Viral Research and Diagnostic Laboratory scheme.
Financial support and sponsorship
The research has been funded by Department of Health Research and Indian Council of Medical Research Government of India, under the Viral Research and Diagnosis Laboratory scheme set up at the Department of Microbiology, Gulbarga Institute of Medical Sciences Kalaburagi, Karnataka.
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