Clinical Study: Chikungunya and Dengue Virus Co-infection in India

This report presents a comparative study of clinical features between monotypic and dual infection cases with Chikungunya virus (CHIKV) and Dengue virus (DENV) in West Bengal, India, conducted in 2010. The study analyzed 550 blood samples for IgM antibodies against both viruses, revealing that 23.8% were positive for CHIKV, 18.9% for DENV, and 12.4% for both. Common clinical features included fever, joint pain, rashes, headache, myalgia, and nausea/vomiting. Severe arthralgia and joint swelling were more prevalent in CHIKV-positive cases, while abdominal pain was associated with DENV infection. Notably, diarrhea was reported only in dual-infected patients. The study also found a higher prevalence of co-infection among adult females and identified October and November as peak months for co-infection cases, correlating with the post-monsoon period and vector mosquito breeding patterns. The findings highlight the co-circulation of CHIKV and DENV and the importance of epidemiological and virological investigations to mitigate potential devastating effects, especially in vulnerable populations.

Am. J. Trop. Med. Hyg., 86(4), 2012, pp. 720–723
doi:10.4269/ajtmh.2012.11-0704
Copyright © 2012 by The American Society of Tropical Medicine and Hygiene
Short Report: A Comparative Study of Clinical Features between Monotypic and
Dual Infection Cases with Chikungunya Virus and Dengue Virus in West Bengal, India
Debjani Taraphdar, Arindam Sarkar, Bansi B. Mukhopadhyay, and Shyamalendu Chatterjee*
ICMR Virus Unit, GB- 4, ID and BG Hospital, Beliaghata, Kolkata, India; Department of Medical Statistics,
Burdwan Medical College, Burdwan, India
Abstract. Chikungunya virus (CHIKV) and dengue virus (DENV) are circulating individually in the state of West
Bengal, India. However, after 1965 the dual-infection caused by both viruses had not been recorded until 2010. In 2010,
an investigation of the febrile cases was carried out to confirm the involvement of both viruses simultaneously. A total
of 550 blood samples were tested for the detection of immunoglobulin M (IgM) antibody against both CHIKV and
DENV. Serology by the enzyme-linked immunosorbent assay method confirmed that 131 (23.8%) and 104 (18.9%)
patients had IgM antibody against CHIKV and DENV,respectively,whereas 68 (12.4%) had IgM antibodies against
both CHIKV and DENV. Fever, joint pain, rashes, headache, myalgia, and nausea/vomiting are the common features in
the case of both monotypic and dual-infection. Severe arthralgia and swelling of joints were common only in CHIKV-
positive cases and abdominal pain was mainly associated with DENV infection. Diarrhea was reported only by the dual-
infected patients (16.2%).
Arthropod-borne viruses or arboviruses are one of the major
public health problems worldwide.Out of many arboviruses,
chikungunya virus (CHIKV) and dengue virus (DENV) are
the two most rapidly spreading arboviruses.The CHIKV
belongs to the genus Alphavirus ofthe Togaviridae family,
whereas DENV belongs to the family Flaviviridae and genus
Flavivirus. To date, both CHIKV and DENV are co-circulating
in India and SoutheastAsia.1 Both virusesare the RNA
virus and the diseasescaused by them are transmitted to
humans by the vector mosquitoes Aedes aegyptiand Aedes
albopictus.2 Both diseaseshave some common signsand
symptoms that include fever, rashes, joint pain, nausea, head-
ache, and vomiting.
In India, CHIKV was first recorded in WestBengalin
1963–65 along with the dengue outbreak.3 Chikungunya cases
were not recorded in West Bengal after that outbreak,how-
ever until1973,severaloutbreaks caused by CHIKV were
recorded from other states of India.4 After that the virus dis-
appeared from India.5 In 2005–2006, CHIKV outbreaks were
reported from many states of India, including West Bengal.6
Dengue is one of the rapidly spreading infections affecting
50 million people per year.7 In India, DENV was first isolated
in Kolkata in 1824,8 however the outbreak caused by DENV
was first recorded in Kolkata in 1963.
Co-circulation of CHIKV and DENV is not uncommon in
South-East Asia.9–11In India, concurrent isolation of CHIKV
and DENV had been reported since 1964 from different
States.2,9In 2010, a hospital-based study revealed co-circulation
of CHIKV and DENV in some areas of West Bengal,India
with high morbidity.
The aim of our work was to study the socio-demographic
features of dual-infected cases,suffered from both CHIKV
and DENV infection simultaneously and to compare the
clinical featuresbetween the monotypic and dual-infected
patients in West Bengal,India. For this purpose,in 2010,a
study was conducted from the suspected cases,referred by
the district health authority and by the clinicians of different
hospitals.Sampleswere collected from the patients admit-
ted with high fever (> 39 °C) and any two ofthe following
symptoms,i.e.,rashes,joint pain,swelling ofjoints,nausea/
vomiting, headache, myalgia, and retro-orbital pain. The local
hospitals reported the absence of bacterial etiology and para-
sites in the blood samples.Informed consentwas obtained
from the patientor from the parents or legalguardians of
minors before the collection of samples. A total of 550 samples
were referred by the clinicians to our department for detec-
tion of CHIKV or DENV with detailed socio-demographic
informationand clinical history. Written consentswere
obtained before collection of the samples.Leukocyte counts
of the patients were 3.5
+109/L-5
+109/L and the platelet counts
were 105
+109/L-160
+109/L. The sera were separated from
the clotted blood samples and stored in aliquots at −80 °C for
further use.
All of the sampleswere subjected to an enzyme-linked
immunosorbentassay (ELISA) test to detectthe presence
of immunoglobulin M (IgM) antibodies against both CHIKV
and DENV by IgM antibody-capture (MAC)-ELISA kits.
The kits were purchased from the National Institute ofVirol-
ogy, Pune, India.12 Optical density (OD) was measured at
492 nm using an ELISA reader. The normal deviate test was
performed to compare the data. The Z-values were calculated
manually. The P value < 0.05 was considered significant.
Out of 550 samples, 131 (23.8%) and 104 (18.9%) samples
were positive to IgM antibody againstonly CHIKV and
DENV, respectively, whereas, 68 (12.4%) samples were posi-
tive to IgM antibody against both CHIKV and DENV.No
cross reactivity was observed between the two viruses.
For the reverse transcription-polymerase chain reaction
(RT-PCR) test, viral RNA was isolated from all the samples
by using the Qiagen viral RNA isolation kit (Qiagen, GmbH,
Hilden, Germany).The RT-PCR test was performed follow-
ing the cost-effective RT-PCR method fordetecting both
CHIKV and DENV. 13 The DENV typing was performed
by using nested PCR with serotype-specific primers.14 Out of
550 samples tested,both DENV and CHIKV were detected
in 24 samples;of which 18 samples contained DEN-2 sero-
type and 6 samples contained DEN-3 serotype. The IgM anti-
body againstDENV or CHIKV was not detected in these
24 samples. The CHIKV RNA was detected in another seven
*Address correspondence to Shyamalendu Chatterjee,ICMR Virus
Unit, GB- 4, 1st Floor, ID and BG Hospital, 57,Dr. S.C. Banerjee
Road, Beliaghata, Kolkata-700010, India. E-mail: shyamalenduchatterjee@
gmail.com
720

samples that were positive by the ELISA method for DENV.
No viral RNA was detected in the samples that were IgM
positive against CHIKV by the ELISA method.
Demographic profiles of the IgM positive cases have been
given in Table 1. Out of 68 IgM positive dual-infected cases,
only six patients (8.8%) were £ 15 years of age. Adults were
more affected by both viruses.However,the populations in
different age groups are not uniformly distributed and hence
the relative ratio ofthe children and adultsin the dual-
infected groups cannot be compared, and the result envisages
only the tip of the iceberg. The highest number of co-infected
cases was found in the age group of31–40 years (27.9%)
(Figure 1). The female/male ratio was 1.72:1, which is signifi-
cantly high (P = 0.03). The females were much more affected
than males because they reside in the house at daytime and
may get exposed to the vector Aedes sp.,which is domestic
in nature and a day biter.15–17No significant difference was
observed between the residentsof urban/semi-urban and
rural areas,although people in the urban/semi-urban areas
were more affected by both monotypic and dual infection.
A comparison of clinicalfeatures is presented in Table 2.
Fever is the most common feature in both single and dual
infection, followed by joint pain, rashes, headache, and nausea
vomiting.Biphasicfever was found in all the dual infec-
ted cases.Swelling ofjoints and severe arthralgia are the
common symptoms in the case of CHIKV infection,but was
rare among the dual-infected patients.Most of the cases with
only DENV infection were associated with abdominalpain,
which was presentin only one case with dualinfection by
both CHIKV and DENV. The most interestingobserva-
tion made in this study wasthe clinicalfeature diarrhea,
which was reported only by the dual-infectedpatients
(16.2%).All the dual infected patientsrecovered quickly.
In all cases the OD value of the Chikungunya IgM antibody
was at least four times higher than the OD value of the dengue
IgM antibody.
Table 1
Demographic features of the IgM-positive cases in West Bengal,India in 2010
Variables
No. of cases (%)
Chikungunya Dengue Co-infection
(N = 131) (N = 104) (N = 68)
Age groups (years) Adult (³ 16 years) 117 (89.3%) 59 (56.7%) 62 (91.2%)
Children (0–15 years) 14 (10.7%) 45 (43.3%) 06 (8.8%)
P value – – –
Gender Male (39.7%) 40 (38.5%) 25 (36.76%)
Female 79 (60.3%) 64 (61.5%) 43 (63.24%)
P value P = 0.03 P = 0.0188 P = 0.03
Place of residence Urban/semi urban 98 (74.8%) 70 (67.3%) 42 (61.76%)
Rural 33 (25.2%) 34 (32.7%) 26 (38.24%)
P value P = 0.001 P = 0.005 P = 0.012
Figure 1. Age-wise distribution of the immunoglobulin M (IgM)-positive cases in West Bengal, India, 2010.
DUAL INFECTION WITH CHIKUNGUNYA AND DENGUE VIRUS IN INDIA 721

Regarding the monthly distribution ofco-infected cases,
the highest number of cases was found in the month of Octo-
ber (43.3%) followed by the month ofNovember (31.3%)
(Figure 2). The stagnant fresh water during the rainy seasons
(June to September) favored the breeding of the vector mos-
quitoes.Therefore,the co-infected casesattained itspeak
in the month of October, which is the post-monsoon period.
In West Bengal,the first CHIKV outbreak was recorded
during 1963 to 1965 in Kolkata,(formerly Calcutta) along
with the outbreak of DENV. After 1965, CHIKV totally dis-
appeared from this region. In 2006, after a gap of 40 years, the
virus again reappeared.15 It has been observed by us that by
2010 CHIKV had gradually grabbed almost every district of
this state by replacing the Asian genotype to Central/East
African genotype (unpublished data).
The state of West Bengalis an endemic zone of DENV.8
Severaloutbreaks have been reported from this region.8,18
Although both viruses individually affected a large number of
people of this state, after 1965, the dual infection caused by both
viruses were recorded in 2010 from this region.The possible
reason for dual infection may be because in West Bengal and
in India the mosquitoes Ae.aegyptiand Ae. albopictus are
abundantly present and are also the vectors for CHIKV and
DENV. 19Aedes aegypti are predominated mainly in the urban
areas,whereas Ae.albopictus can survive in both ruraland
urban environments.20 The vectors can carry both of the virus,
which might have facililtated the spreading of the dual infection
in both rural and urban regions.
Some man-made situations such as urbanization, industrial-
ization,and deforestation result in vector shuffling in many
Table 2
Clinical characteristic of co-infected patients referred from different medical colleges and hospitals in West Bengal,India in 2010
Clinical features
Chikungunya cases (%) Dengue cases (%) Co-infected cases (%)
(N = 131) (N = 104) (N = 68)
Fever 131 (100) 104 (100) 68 (100)
Joint pain 92 (70.2) 45 (43.3) 53 (77.9)
Rash 52 (39.7) 19 (18.3) 40 (58.8)
Headache 53 (40.5) 60 (57.7) 28 (41.2)
Myalgia/body ache 40 (30.5) 46 (44.2) 7 (10.3)
Itching 23 (17.6) 12 (11.5) 8 (11.8)
Nausea/vomiting 27 (20.6) 41 (39.4) 6 (8.8)
Joint swelling 85 (64.9) 4 (3.8) 8 (11.8)
Arthralgia/difficulty in movement 79 (60.3) 0 0
Abdominal pain 0 22 (21.2) 1 (1.5)
Retro-orbital pain/redness of eyes 0 8 (7.7) 4 (5.8)
Diarrhea 0 0 11 (16.2)
Figure 2. Monthly distribution of immunoglobulin M (IgM)-positive cases in West Bengal in 2010.
722 TARAPHDAR AND OTHERS

areas and raises the vector densities.18 The DENV can cause
severe hemorrhagic illnessand CHIK, although generally
“benign,” butcan cause severe neurologicalillness.There-
fore, furtherepidemiologicaland virologicalinvestigations
for both viruses are required,because these may create dev-
astative effects, particularly in children and young adults who
may not possess the CHIKV and DENV antibody.
Received November 11, 2011. Accepted for publication January 27, 2012.
Acknowledgments:We are indebted to the Officer-In-Charge,
ICMR Virus Unit, Sekhar Chakrabarti, for allowing us to carry out
the work in this Department.The enthusiasticrepeated help
obtained from the clinicians of the MedicalColleges and District
Hospitals for providing us the clinically suspected samples for this
study is gratefully acknowledged. We express a sincere gratitude to
all the staff members of ICMR Virus Unit, for their constant help and
assistance.The American Committee on ClinicalTropicalMedicine
and Travelers’ Health (ACCTMTH) assisted with publication expenses.
Financialsupport:This study was supported by Indian councilof
medical research, New Delhi, India.
Authors’ addresses:Debjani Taraphdar, Arindam Sarkar, and
Shyamalendu Chatterjee, ICMR Virus Unit, ID and BG Hospital Cam-
pus, Beliaghata, Kolkata, India, E-mails: [e-mail],
[e-mail],and [e-mail].
Bansi B. Mukhopadhyay, KPC Medical College and Hospital, Jadavpur,
Kolkata, India, E-mail: [e-mail].
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