N PRADEEP KUMAR | ICMR (original) (raw)

Papers by N PRADEEP KUMAR

PLOS Neglected Tropical Diseases, 2023

The present study explicitly evaluated the genetic structure of Aedes aegypti Linn, the vector of... more The present study explicitly evaluated the genetic structure of Aedes aegypti Linn, the vector
of dengue, chikungunya, and Zika viruses, across different geo-climatic zones of India and
also elucidated the impact of ecological and topographic factors. After data quality checks
and removal of samples with excess null alleles, the final analysis was performed on 589
individual samples using 10 microsatellite markers. Overall findings of this study suggested
that, Ae. aegypti populations are highly diverse with moderate genetic differentiation
between them. Around half of the populations (13 out of 22) formed two genetic clusters
roughly associated with geographical regions. The remaining nine populations shared
genetic ancestries with either one or both of the clusters. A significant relationship between
genetic and geographic distance was observed, indicating isolation by distance. However,
spatial autocorrelation analysis predicted the signs of long-distance admixture. Post-hoc
environmental association analysis showed that 52.7% of genetic variations were explained
by a combination of climatic and topographic factors, with latitude and temperature being
the best predictors. This study indicated that though overall genetic differentiation among
Ae. aegypti populations across India is moderate (Fst = 0.099), the differences between the
populations are developing due to the factors associated with geographic locations. This
study improves the understanding of the Ae. aegypti population structure in India that mayassist in predicting mosquito movements across the geo-climatic zones, enabling effective
control strategies and assessing the risk of disease transmission.

Journal of Tropical Medicine, 2023

Wolbachia, a Gram•negative intracellular bacterium, naturally infects many arthropods, including ... more Wolbachia, a Gram•negative intracellular bacterium, naturally infects many arthropods, including mosquito vectors responsible for the spread of arboviral diseases such as Zika, chikungunya, and dengue fever. Certain Wolbachia strains are involved in inhibiting arbovirus replication in mosquitoes, and this phenomenon is currently being studied to combat disease vectors. A study was conducted in four states in north•eastern India to investigate the presence of natural Wolbachia infection in wild•caught Aedes albopictus and Aedes aegypti mosquitoes, the established vectors of dengue. Te detection of a Wolbachia infection was confrmed by nested PCR and sequencing in the two mosquito species Ae. aegypti and Ae. albopictus. Positivity rates observed in Ae. aegypti and Ae. albopictus pools were 38% (44 of 115) and 85% (41 of 48), respectively, and the diference was signifcant (chi• square � 28.3174, p � 0.00000010). Sequencing revealed that all detected Wolbachia strains belonged to supergroup B. Although Wolbachia infection in Ae. aegypti has been previously reported from India, no such reports are available from north•eastern India. Data on naturally occurring Wolbachia strains are essential for selecting the optimal strain for the development of Wolbachia•based control measures. Tis information will be helpful for the future application of Wolbachia•based vector control measures in this part of the country.

PLoS Negl Trop Dis, 2023

The present study explicitly evaluated the genetic structure of Aedes aegypti Linn, the vector of... more The present study explicitly evaluated the genetic structure of Aedes aegypti Linn, the vector of dengue, chikungunya, and Zika viruses, across different geo-climatic zones of India and also elucidated the impact of ecological and topographic factors. After data quality checks
and removal of samples with excess null alleles, the final analysis was performed on 589 individual samples using 10 microsatellite markers. Overall findings of this study suggested that, Ae. aegypti populations are highly diverse with moderate genetic differentiation between them. Around half of the populations (13 out of 22) formed two genetic clusters
roughly associated with geographical regions. The remaining nine populations shared genetic ancestries with either one or both of the clusters. A significant relationship between genetic and geographic distance was observed, indicating isolation by distance. However,
spatial autocorrelation analysis predicted the signs of long-distance admixture. Post-hoc environmental association analysis showed that 52.7% of genetic variations were explained by a combination of climatic and topographic factors, with latitude and temperature being
the best predictors. This study indicated that though overall genetic differentiation among Ae. aegypti populations across India is moderate (Fst = 0.099), the differences between the populations are developing due to the factors associated with geographic locations. This study improves the understanding of the Ae. aegypti population structure in India that may assist in predicting mosquito movements across the geo-climatic zones, enabling effective control strategies and assessing the risk of disease transmission.

International Journal of Tropical Insect Science , 2023

Sandflies (Diptera: Psychodidae) are medically important insects prevalent in tropical and temper... more Sandflies (Diptera: Psychodidae) are medically important insects prevalent in tropical and temperate regions of the world. About 30 species of these flies have been recorded from the Western Ghats region of Kerala. While carrying out epidemiological investigations on Leishmaniasis in this region, we found two species of field-collected sandflies viz., Phlebotomus argentipes and Sergentomyia monticola infected with Tylenchid nematode parasites. The infection rates were 0.89% and 0.9%, respectively. The parasite density of nematode juvenile stages was more than 1000 in all the specimens. Both males and females were found infected. We performed molecular characterization of these nematode parasites using multiple genetic markers, mitochondrial COI, and two different regions of 18S rDNA. The genetic analysis revealed that the nematode belonged to the genus Howardula of family Allantonematidae, one infesting P. argentipes (major vector species of Leishmania) and the other, S. monticola. This is the first report of natural infection with the entomo-parasitic nematode species, belonging to Allantonematidae among these sandfly species from India. Genetically related and unclassified species of nematodes belonging to this family had been reported elsewhere from termite species. As larval stages of sandflies develop in the organic matter of termite mounds, this finding may have significant implications on their bionomics and control.

The Lancet Regional Health - Southeast Asia, 2023

Background Dengue shows high geographic heterogeneity within and across endemic countries. In the... more Background Dengue shows high geographic heterogeneity within and across endemic countries. In the context of increasing burden and predicted outbreaks due to climate change, understanding the heterogeneity will enable us to develop region specific targeted interventions, including vaccination. World Health Organisation (WHO) suggests standard methodologies to study the burden and heterogeneity at national and subnational levels. Regional studies with robust and standard methodology to capture heterogeneity are scarce. We estimated the seroprevalence of dengue in children aged 9-12 years and the force of infection in Kerala, India, from where Zika cases also have been reported recently. Articles exceeds the reported numbers. Heterogeneity in prevalence, the high proportion of inapparent dengue and the hyperendemic situation suggest the need for region-specific and targeted interventions, including vaccination. Funding World Health Organization.

Journal of Clinical Virology Plus, 2021

Background: After the 2007 epidemic, a major outbreak of chikungunya was reported from Thiruvanan... more Background: After the 2007 epidemic, a major outbreak of chikungunya was reported from Thiruvananthapuram, Kerala, India during 2019-2020. Study design: A cross sectional survey was conducted during the period to elucidate the clinical profile of patients and the genotype of CHIKV involved in the infections in one of the worst affected villages. Patients (n = 148) meeting WHO case definition were recruited both prospectively and retrospectively. All the samples were subjected to either RT-PCR or IgM ELISA based on the duration of symptoms. The CHIKV envelope gene sequences amplified among the positives were analyzed. Data on socio-demographic details, mosquito control practices, clinical features, details of hospitalization and treatment were collected. Results: Among the CHIKV suspected cases, 38 were recruited prospectively and 110 retrospectively. Among the former group 92% tested positive for CHIKV infection by either PCR or ELISA. Fever (51.4%) and joint pain (20.0%) were the presenting symptoms. More than 45% of the subjects had involvement of the knee joints. CHIKV Envelope gene sequence analysis indicated that all the cases belonged to the genetic lineage similar to 2006 outbreak CHIKV in Kerala. In addition, two novel non-synonymous mutations, K211E and I317V was recorded. Conclusions: The clinical presentation of Chikungunya has shown some changes compared to previous epidemic. Fever was reported to be the initial symptom of the clinical profile. Implication of the two additional mutations found in the envelope gene of the virus needs further exploration towards recent increasing trend of CHIKV infection in the state.

Scientific Reports, 2021

Dengue, caused by the dengue virus (DENV) is a signifcant vector-borne disease. In absence of a s... more Dengue, caused by the dengue virus (DENV) is a signifcant vector-borne disease. In absence of a
specifc treatment and vaccine, dengue is becoming a rising threat to public health. Currently, control
of dengue mainly focuses on the surveillance of the mosquito vectors. Improved surveillance methods
for DENV in mosquito populations would be highly benefcial to the public health. However, current
methods of DENV detection in mosquitoes requires specialized equipment and expensive reagents
and highly trained personnel. As an alternative, commercially available dengue NS1 antigen ELISA
kits could be used for detection of DENV infection in Aedes aegypti mosquitoes. In this study, we
explored the utility of commercially available Dengue NS1 antigen kit (J. Mitra & Co. Pvt. Ltd) for the
detection of recombinant dengue virus-2 (rDENV-2) NS1 protein and serum of dengue infected patient
spiked with Ae. aegypti mosquito pools. The kit was found to be highly sensitive and specifc towards
detection of all serotypes of DENV. Further, it could detect as low as 750 femto gram rDENV-2 NS1
protein. It was also observed that rDENV-2 NS1 antigen spiked with blood-fed and unfed mosquito
pools could be detected. In addition, the kit also detected dengue infected patient serum spiked
with Ae. aegypti mosquito pools. Overall, the Dengue NS1 antigen kit displayed high sensitivity
towards detection of recombinant as well as serum NS1 protein spiked with Ae. aegypti mosquito
pools and could be considered for the dengue virus surveillance after a feld evaluation in Ae. aegypti
mosquitoes.

Transactions of The Royal Society of Tropical Medicine and Hygiene, 2023

Background Culex quinquefasciatus is a notorious vector known to transmit pathogens such as Wuche... more Background
Culex quinquefasciatus is a notorious vector known to transmit pathogens such as Wuchereria bancrofti (causing Lymphatic filariasis) and flaviviruses such as West Nile virus in India and St. Louis Encephalitis virus in the USA. It is the vector of the Rift Valley Fever virus, also on the African continent. Mosquitoes also harbor other non-pathogenic insect-specific flaviviruses (ISFs), such as Culex flavivirus (CxFV) and Aedes flavivirus. Recent studies have implicated ISFs interfering with the vectorial efficiency of the pathogenic arbo-viruses.

Methods
One hundred specimens of the Cx. quinquefasciatus population in two urban areas in Kerala State, India, were screened to have an understanding of the prevalence of these flaviviruses in this vector species. Viral RNA was extracted from individual specimens and was subjected to RT-PCR towards amplification of the CxFV non-structural protein 5 (NS5) gene.

Results
Among the 100 specimens, 7.0% were found to be harboring CxFV infection. The phylogenetic analysis of the gene sequences showed that the virus isolates were genetically related to Kenya, with 98–99% sequence similarities.

Conclusion
This is the first report on the occurrence of CxFV from Cx. quinquefasciatus from India. The occurrence of these viruses in mosquitoes could play a critical role in disease vector management.

The American Journal of Tropical Medicine and Hygiene, 2023

The tribal population in and around the Western Ghats region of India is affected by both cutaneo... more The tribal population in and around the Western Ghats region of India is affected by both cutaneous leishmaniasis (CL) and visceral leishmaniasis (VL) with typical clinical symptoms. In this study, we recorded and analyzed seven CL and three VL cases from this emerging belt. All the cases were found as autochthonous transmission. Multiple genetic markers (minicircle kinetoplast DNA polymerase chain reaction and restriction fragment length polymorphism of 3'untranslated region heat shock protein (HSP) 70, a larger segment of HSP 70, and 6-phosphogluconate dehydrogenase [PGDH] gene sequences) were used to identify and characterize the parasite. It was found that both clinical manifestations are caused by zymodeme MON-37 of Leishmania donovani. We have investigated the detailed entomological and epidemiological aspects of disease transmission. An abundant population of the proven vector Phlebotomus argentipes was observed in the study villages.

Parasitology Research, 2024

Leishmaniasis transmission cycles are maintained and sustained in nature by the complex crosstalk... more Leishmaniasis transmission cycles are maintained and sustained in nature by the complex crosstalk of the Leishmania parasite, sandfly vector, and the mammalian hosts (human, as well as zoonotic reservoirs). Regardless of the vast research on human host-parasite interaction, there persists a substantial knowledge gap on the parasite’s development and modulation in the vector component. This review focuses on some of the intriguing aspects of the Leishmania-sandfly interface, beginning with the uptake of the intracellular amastigotes from an infected host to the development of the parasite within the sandfly’s alimentary canal, followed by the transmission of infective metacyclic stages to another potential host. Upon ingestion of the parasite, the sandfly hosts an intricate repertoire of immune barriers, either to evade the parasite or to ensure its homeostatic coexistence with the vector gut microbiome. Sandfly salivary polypeptides and Leishmania exosomes are co-egested with the parasite inoculum during the infected vector bite. This has been attributed to the modulation of the parasite infection and subsequent clinical manifestation in the host. While human host–based studies strive to develop effective therapeutics, a greater understanding of the vector-parasite-microbiome and human host interactions could help us to identify the targets and to develop strategies for effectively preventing the transmission of leishmaniasis.

Comput Methods Programs Biomed., 2020

Dengue virus (DENV) is an emerging health threat and its envelope glycoprotein E, is involved in ... more Dengue virus (DENV) is an emerging health threat and its envelope glycoprotein E, is involved in the anchoring and fusion mechanisms. Anchoring followed by conformational changes of E-protein are responsible for the fusion and entry of DENV into host. The variation in the conformation of the E-protein due to mutations, results in its altered binding with antibodies (Abs) and also its receptors. This leads to failure of neutralization of DENV and enhance the infection. In our earlier studies we have identified T219A mutation in the E-protein of DENV and the present study is focused on the impact of this mutation on the conformation of E-protein and also its binding variation with Abs and Fc-γ receptor. A comparative molecular modelling studies of wild type and T219A mutant E-proteins revealed that, the mutation induced several conformational variations in the E-protein and resulted in the variable binding orientation with altered affinities. Further, the mutation was also observed to enhance the fusion mechanism by Fc-γ receptors that mediate the efficient entry of DENV into host cell through altered membrane fusion mechanism. Such conformational variations of E-protein could be the responsible factors for enhanced virulence of DENV infections.

Current Science, 2021

Dengue fever is a major public health concern in India and Kerala is one of the worst affected st... more Dengue fever is a major public health concern in India
and Kerala is one of the worst affected states in the
country. Kanjirappally, Kottayam district, has been
reported to be the epicentre of dengue in the state. In
2016, we carried out a post-epidemic seroprevalence
survey in both urban and rural sites of this endemic
foci to estimate the disease burden. A systematic sampling
technique with a random start (household) was
adopted in each study site. Overall, 938 individuals
were enrolled in the survey, 470 in the urban and 468
in the rural sites belonging to 103 and 88 households
respectively. Rapid diagnostic IgM/IgG test kit was
used for the study. The overall dengue IgG seroprevalence
observed was 51.28%. Urban sites had higher
seroprevalence rate (59.8%) compared to rural sites
(42.74%, P < 0.01). No gender difference was recorded
in seroprevalence rates among the sites. Exposure was
found to be more common among adults than children
in both areas. Seroprevalence rate in children <10
years of age was found to be 15 times higher (44.61%)
in urban sites, than that in the rural sites (3.03%).
The present study indicates that more than half of the
population is exposed to DENV (dengue virus) infection
in this oldest focus of dengue in Kerala.

International Journal of Infectious Diseases, 2021

Objectives: Following the Public Health Emergency of International Concern declared on Zika by th... more Objectives: Following the Public Health Emergency of International Concern declared on Zika by the World Health Organization during 2016, the Indian Council of Medical Research carried out nationwide vector surveillance for Zika and Dengue viruses (ZIKV and DENV) in India as a preparedness measure in 2016-19. Methods: High-risk zones distributed to 49 Districts in 14 states/union territories were included in the study. Seven ICMR institutions participated, following a standard operating protocol. Aedes specimens sampled weekly were processed by multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) for ZIKV/DENV and random samples crosschecked with real-time RT-PCR for ZIKV. Results: Altogether, 79 492 Aedes specimens in 6492 pools were processed; 3 (0.05%) and 63 (0.97%) pools, respectively, were found positive for ZIKV and DENV. ZIKV infections were recorded in Aedes aegypti sampled during the 2018 sporadic Zika outbreak in Jaipur, Rajasthan. However, these belonged to the Asian lineage of the virus, already circulating in the country. Both Ae. aegypti and Aedes albopictus distributed to 8 states/union territories were found to be infected with DENV. Both sexes of Ae. albopictus were infected, indicating transovarial transmission. Conclusion: This investigation evinced no active transmission of the American lineage-pandemic Zika virus in India during the pandemic period.

Transactions of the Royal Society of Tropical Medicine and Hygiene, 2022

Background In the context of the largest dengue outbreak in the state of Kerala, India in 2017, a... more Background
In the context of the largest dengue outbreak in the state of Kerala, India in 2017, along with global evidence of changing epidemiology of dengue virus and its distribution, this study was planned to understand the epidemiological pattern of dengue infection and contemplate the clinical presentations of different serotypes.

Methods
This cross-sectional study was conducted in the Thiruvananthapuram and Kollam districts of Kerala, India, spanning 3 y from 2017 to 2019. We recruited adult patients based on the World Health Organization case definition of probable dengue fever to study their virological, spatial and clinical characteristics.

Results
Dengue infection was identified in 113 (33.9%) of the 333 probable dengue patients recruited. Dengue virus 1 (DENV1), along with its combinations (59.09%), was the predominant serotype during 2017, followed by DENV2. There was a marked increase in the proportion of DENV4 cases (34.56%) and concurrent infections (26%) in 2019. DENV3 infections were more likely to present with warning signs (adjusted relative risk 6.14 [95% confidence interval 1.3 to 29.4]) and a significantly lower platelet count (p=0.02).

Conclusions
The results highlight the hyperendemicity of dengue infection in the state and the changing pattern of dengue virus predominance along with redominance. The rise in DENV4 and concurrent infections put forth the possibility of a more severe future outbreak.

Zootaxa, 2023

The adult, larval and pupal stages of Downsiomyia rajaveli, a new species (Diptera: Culicidae) fr... more The adult, larval and pupal stages of Downsiomyia rajaveli, a new species (Diptera: Culicidae) from India, are described and illustrated, and the mitochondrial COI barcode is provided for the species. The morphological relationship of the new species to other members of the genus Downsiomyia is discussed.

Journal of Tropical Medicine, 2023

Wolbachia, a Gram-negative intracellular bacterium, naturally infects many arthropods, including ... more Wolbachia, a Gram-negative intracellular bacterium, naturally infects many arthropods, including mosquito vectors responsible for the spread of arboviral diseases such as Zika, chikungunya, and dengue fever. Certain Wolbachia strains are involved in inhibiting arbovirus replication in mosquitoes, and this phenomenon is currently being studied to combat disease vectors. A study was conducted in four states in northeastern India to investigate the presence of natural Wolbachia infection in wild-caught Aedes albopictus and Aedes aegypti mosquitoes, the established vectors of dengue. Te detection of a Wolbachia infection was confrmed by nested PCR and sequencing in the two mosquito species Ae. aegypti and Ae. albopictus. Positivity rates observed in Ae. aegypti and Ae. albopictus pools were 38% (44 of 115) and 85% (41 of 48), respectively, and the diference was signifcant (chisquare � 28.3174, p � 0.00000010). Sequencing revealed that all detected Wolbachia strains belonged to supergroup B. Although Wolbachia infection in Ae. aegypti has been previously reported from India, no such reports are available from northeastern India. Data on naturally occurring Wolbachia strains are essential for selecting the optimal strain for the development of Wolbachia-based control measures. Tis information will be helpful for the future application of Wolbachia-based vector control measures in this part of the country.

Journal of Clinical Trials and Case Studies, 2023

The recent global outbreaks of the ZIKA Virus (ZIKV) reported in 85 countries and territories cau... more The recent global outbreaks of the ZIKA Virus (ZIKV) reported in 85 countries and territories caused severe complications such as microcephaly among neonates and Guillain-Barre Syndrome among the older population. Recently, an outbreak of ZIKV was reported from Thiruvananthapuram, the capital city of Kerala, India with about 70 confirmed cases. We conducted an outbreak investigation and the primary findings are described here. A cluster of ZIKV cases from the Kadakampalli / Anamugham administrative wards of the Thiruvananthapuram Municipal Corporation area was reported where Kerala Institute of Medical Sciences (KIMS) is located. Later many ZIKV cases were reported from other wards of the city. The density of known Aedes vectors was high in this region of the metropolitan city. Aedes albopictus, Aedes aegypti and Aedes vittatus collected from the focal area of the outbreak were found to be naturally infected with ZIKV. Male specimens of Ae. albopictus were naturally infected, indicating trans-ovarian transmission of the virus. This is first report of incrimination of Ae. albopictus and Ae. vittatus in ZIKV transmission from India. The virus was characterized and the partial sequences clustered with the Asian strain of ZIKV reported from India. The NS5 sequences of human and Ae. albopictus pools from Thiruvananthapuram were 100% similar indicating an ongoing active ZIKV transmission. The state health authorities were sensitized and appropriate containment and vector control measures have been initiated to contain the outbreak. This report underscores the importance of continued human and vector surveillance as well as genomic sequencing to understand the virus evolution and implications on public health.

Journal of Evolution of Medical and Dental Sciences, 2018

BACKGROUND Visceral Leishmaniasis (VL) is seen commonly in eastern parts of India, while occurren... more BACKGROUND Visceral Leishmaniasis (VL) is seen commonly in eastern parts of India, while occurrences of cutaneous forms of the disease have been reported recently from Western Ghats of southern India. The clinical manifestations of VL resembles many other chronic illnesses and its diagnosis and management requires added attention in southern parts of the country. The clinical, epidemiological and entomological investigations related to the occurrence of a case of VL in Kerala, south India are described in detail. MATERIALS AND METHODS This study is a descriptive study. The patient suffered from various clinical manifestations which were investigated repeatedly at various primary, secondary and tertiary care institutions. Several laboratory tests for multiple diseases turned out to be negative, even though the symptoms were persisting. Accurate diagnosis was made from the bone marrow cytological examination, which indicated the presence of Leishman-Donovan bodies. Further epidemiological and entomological investigations confirmed the presence of vector (Phlebotomus argentipes) from multiple locations around the residence of the patient. Evidence of Leishmaniasis or its source could not be diagnosed in contacts, vectors or suspected animal reservoirs in the area. RESULTS Accurate diagnosis was made from the bone marrow cytological examination, which indicated the presence of Leishman-Donovan bodies. Epidemiological and entomological investigations confirmed the presence of vector (Phlebotomus argentipes) from multiple locations around the residence of the patient. Evidence of Leishmaniasis or its source could not be diagnosed in contacts, vectors or suspected animal reservoirs in the area. CONCLUSION Early and accurate diagnosis of VL is difficult in south India due to unawareness about the manifestations of disease and also due to unavailability of reliable laboratory kits. The management of such cases is even more challenging due to the lack of availabi lity of proper drugs. The recent reports of emergence of resistant cases should be a pointer in creating improved awareness and facilities for the rapid identification and management of cases of visceral leishmaniasis.

Vector borne and zoonotic diseases (Larchmont, N.Y.), Oct 1, 2018

Outbreaks of acute encephalitis syndrome (AES) with high fatality and disability, are reported ev... more Outbreaks of acute encephalitis syndrome (AES) with high fatality and disability, are reported every year in the Gorakhpur region of Uttar Pradesh, India, with the etiology of >60% of the cases being attributed to scrub typhus. In the present study, the prevalence of Orientia tsutsugamushi, the etiological agent of scrub typhus, was investigated among animal hosts and their ectoparasitic trombiculid mites prevalent in AES-reported areas of Gorakhpur. A total of 154 rodents/shrews were collected using 777 Sherman traps set in 12 study villages, and the overall trap rate was 19.8%. In total, 2726 trombiculid mites belonging to 12 species were collected from 154 rodents/shrews trapped. The shrew mouse Suncus murinus was the predominant animal species (78.6%) collected. The principal vector mite Leptotrombidium deliense was the predominant species (82.7%), and its index was 14.6 per animal. Of 114 rodent/shrew sera samples screened through the Weil-Felix test, 57% were positive for a...

PLOS Neglected Tropical Diseases, 2023

Journal of Tropical Medicine, 2023

PLoS Negl Trop Dis, 2023

The present study explicitly evaluated the genetic structure of Aedes aegypti Linn, the vector of... more The present study explicitly evaluated the genetic structure of Aedes aegypti Linn, the vector of dengue, chikungunya, and Zika viruses, across different geo-climatic zones of India and also elucidated the impact of ecological and topographic factors. After data quality checks
and removal of samples with excess null alleles, the final analysis was performed on 589 individual samples using 10 microsatellite markers. Overall findings of this study suggested that, Ae. aegypti populations are highly diverse with moderate genetic differentiation between them. Around half of the populations (13 out of 22) formed two genetic clusters
roughly associated with geographical regions. The remaining nine populations shared genetic ancestries with either one or both of the clusters. A significant relationship between genetic and geographic distance was observed, indicating isolation by distance. However,
spatial autocorrelation analysis predicted the signs of long-distance admixture. Post-hoc environmental association analysis showed that 52.7% of genetic variations were explained by a combination of climatic and topographic factors, with latitude and temperature being
the best predictors. This study indicated that though overall genetic differentiation among Ae. aegypti populations across India is moderate (Fst = 0.099), the differences between the populations are developing due to the factors associated with geographic locations. This study improves the understanding of the Ae. aegypti population structure in India that may assist in predicting mosquito movements across the geo-climatic zones, enabling effective control strategies and assessing the risk of disease transmission.

International Journal of Tropical Insect Science , 2023

The Lancet Regional Health - Southeast Asia, 2023

Journal of Clinical Virology Plus, 2021

Scientific Reports, 2021

Transactions of The Royal Society of Tropical Medicine and Hygiene, 2023

The American Journal of Tropical Medicine and Hygiene, 2023

Parasitology Research, 2024

Comput Methods Programs Biomed., 2020

Current Science, 2021

International Journal of Infectious Diseases, 2021

Transactions of the Royal Society of Tropical Medicine and Hygiene, 2022

Zootaxa, 2023

Journal of Tropical Medicine, 2023

Journal of Clinical Trials and Case Studies, 2023

Journal of Evolution of Medical and Dental Sciences, 2018

Vector borne and zoonotic diseases (Larchmont, N.Y.), Oct 1, 2018

SSRN - The Lancet preprints, 2023

Background: An outbreak of Zika fever occurred in Thiruvananthapuram City, Kerala, India during 2... more Background: An outbreak of Zika fever occurred in Thiruvananthapuram City, Kerala, India during 2021. We investigated the same, on request of Kerala state health administration towards proposing containment strategies.

Methods: Epidemiological and entomological investigations as well as genome analysis of ZIKA Virus (ZIKV) involved in the infections were performed, targeting crucial and phylogenetically important mutations in the Capsid-pre Membrane, Envelope and Non-Structural protein -5 gene sequences.

Results: A clustering pattern of cases was observed during the outbreak, with the presumed index case from a multi-speciality hospital, in Thiruvananthapuram city. The causative ZIKV belonged to the Asian strain, however, distinct from the pandemic American lineage. The predominant Aedes albopictus (65.55%), Aedes aegypti (22.0%) and Aedes vittatus (12.0%) species were found naturally infected with ZIKV, the Minimum Infection Rates being 17.9, 7.8 and 3.6 respectively. Also, trans-ovarian transmission was recorded in Ae. albopictus.

Conclusions: ZIKV isolates presented with four unique non synonymous mutations viz., “I22T” & “I160M” (pre-Membrane) and “D348N” & “V473L” (Envelope) during the outbreak which’s implications remains to be investigated. Phylogenetic analysis of the gene sequences indicated the emergence of a distinct genetic lineage of ZIKV in India. Our investigations evince the urgent need of development of a systematic country-wide surveillance strategy, towards the prevention/ preparedness/ containment of a massive outbreak of this emerging arbo-viral disease.

Funding: This study was performed utilizing intramural funds of Indian Council of Medical Research-Vector Control Research Centre.

Declaration of Interest: The authors declare no known competing financial interests or personal relationships/interests that could have appeared to influence the work reported in this manuscript.

Ethical Approval: As the study was an outbreak investigation carried out on the request of the Department of Health Services, Government of Kerala. India, institutional ethical approval was not essential the time of investigation. Most of the samples processed were from mosquito specimens. Informed consent forms were obtained from all the four patients from whom blood samples were obtained during the investigation. However, towards on going further investigations institutional ethical approval was obtained retrospectively.