Emerging viral diseases of Southeast Asia and the Western Pacific

A tale of endurance: bats, viruses and immune dynamics

The emergence of highly zoonotic viral infections has propelled bat research forward. The viral outbreaks including Hendra virus, Nipah virus, Marburg virus, Ebola virus, Rabies virus, Middle East respiratory syndrome coronavirus, SARS-CoV and the latest SARS-CoV-2 have been epidemiologically linked to various bat species. Bats possess unique immunological characteristics that allow them to serve as a potential viral reservoir. Bats are also known to protect themselves against viruses and maintain their immunity. Therefore, there is a need for in-depth understanding into bat-virus biology to unravel the major factors contributing to the coexistence and spread of viruses.

Coinfection and circulation of chikungunya virus and dengue virus in pediatric patients in Myanmar, 2019

Myanmar is an endemic country for arboviruses, and outbreaks occur frequently. A cross-sectional analytical study was conducted during the peak season of the chikungunya virus (CHIKV) outbreak in 2019. A total of 201 patients with acute febrile illness who were admitted to the 550-bedded Mandalay Children Hospital in Myanmar were enrolled in the study, and virus isolation, serological tests, and molecular tests for the dengue virus (DENV) and CHIKV were performed for all samples. Out of 201 patients, 71 (35.3%) were only DENV-infected, 30 (14.9%) were only CHIKV-infected and 59 (29.4%) were coinfected with DENV and CHIKV. The viremia levels of the DENV- and CHIKV- mono-infected groups were significantly higher than those of the group coinfected with DENV and CHIKV. Genotype I of DENV-1, genotypes I and III of DENV-3, genotype I of DENV-4 and the East/Central/South African genotype of CHIKV were co-circulating during the study period. Two novel epistatic mutations of CHIKV (E1:K211E and E2:V264A) were noted. This study highlighted that there were many coinfection cases during the outbreak and that the co-circulation of both viruses in DENV-endemic regions warrants effective monitoring of these emerging pathogens via comprehensive surveillance to facilitate the implementation of effective control measures.

An Overview of Indian Biomedical Research on the Chikungunya Virus with Particular Reference to Its Vaccine, an Unmet Medical Need

Chikungunya virus (CHIKV) is an infectious agent spread by mosquitos, that has engendered endemic or epidemic outbreaks of Chikungunya fever (CHIKF) in Africa, South-East Asia, America, and a few European countries. Like most tropical infections, CHIKV is frequently misdiagnosed, underreported, and underestimated; it primarily affects areas with limited resources, like developing nations. Due to its high transmission rate and lack of a preventive vaccine or effective treatments, this virus poses a serious threat to humanity. After a 32-year hiatus, CHIKV reemerged as the most significant epidemic ever reported, in India in 2006. Since then, CHIKV-related research was begun in India, and up to now, more than 800 peer-reviewed research papers have been published by Indian researchers and medical practitioners. This review gives an overview of the outbreak history and CHIKV-related research in India, to favor novel high-quality research works intending to promote effective treatment and preventive strategies, including vaccine development, against CHIKV infection.

Potential biomarkers in Japanese encephalitis from different hosts and geographical locations

Japanese encephalitis (JE) is a single-stranded, mosquito-borne, positive-sense RNA flavivirus that causes one of the most severe encephalitides. There are treatments available for those who contact this illness; however, there are no known cures. This disease has a 30% fatality rate, and of the people who survive, 30-50% develops neurologic and psychiatric sequelae. The JE virus genome size is 10.98 kb and contains two coding DNA sequences (CDS), two genes, and 15 mature peptides; the CDS polyprotein is 10.3 kb. In this study, we used 29 genomics sequences of the JE virus reported from different countries and infecting different animals and analysed vast dimensions of the genomic annotation of JE comparatively to understand its evolutionary aspects. The extensive SNPs analysis revealed that KF907505.1, reported from Taiwan, has only three SNPs, similar to sequences reported from India. Repeat and polymorphism analyses revealed that the genome tends to be similar in most JE sequences.

Evaluating the mosquito host range of Getah virus and the vector competence of selected medically important mosquitoes in Getah virus transmission

BACKGROUND

The Getah virus (GETV) is a mosquito-borne Alphavirus (family Togaviridae) that is of significant importance in veterinary medicine. It has been associated with major polyarthritis outbreaks in animals, but there are insufficient data on its clinical symptoms in humans. Serological evidence of GETV exposure and the risk of zoonotic transmission makes GETV a potentially medically relevant arbovirus. However, minimal emphasis has been placed on investigating GETV vector transmission, which limits current knowledge of the factors facilitating the spread and outbreaks of GETV.

METHODS

To examine the range of the mosquito hosts of GETV, we selected medically important mosquitoes, assessed them in vitro and in vivo and determined their relative competence in virus transmission. The susceptibility and growth kinetics of GETVs in various mosquito-derived cell lines were also determined and quantified using plaque assays. Vector competency assays were also conducted, and quantitative reverse transcription-PCR and plaque assays were used to determine the susceptibility and transmission capacity of each mosquito species evaluated in this study.

RESULTS

GETV infection in all of the investigated mosquito cell lines resulted in detectable cytopathic effects. GETV reproduced the fastest in Culex tritaeniorhynchus- and Aedes albopictus-derived cell lines, as evidenced by the highest exponential titers we observed. Regarding viral RNA copy numbers, mosquito susceptibility to infection, spread, and transmission varied significantly between species. The highest vector competency indices for infection, dissemination and transmission were obtained for Cx. tritaeniorhynchus. This is the first study to investigate the ability of Ae. albopictus and Anopheles stephensi to transmit GETV, and the results emphasize the role and capacity of other mosquito species to transmit GETV upon exposure to GETV, in addition to the perceived vectors from which GETV has been isolated in nature.

CONCLUSIONS

This study highlights the importance of GETV vector competency studies to determine all possible transmission vectors, especially in endemic regions.

Dengue-chikungunya infection in the tertiary care hospital of northern India: Cross-sectional latent class cluster analysis in viral infection

Cases of dengue and chikungunya fever are escalating all over India. Both viruses share a common vector, the "Aedes" mosquito. Due to similar clinical symptoms, both the dengue (DENV) and chikungunya (CHIKV) virus can circulate as co-infection. There is very limited data available on dengue-chikungunya co-infection in Uttarakhand, India. The purpose of this study was to determine the seroprevalence of dengue and chikungunya virus infections, as well as their co-infection, in patients presenting with clinical symptoms. Serum samples of clinically suspected patients from the tertiary care hospital of Uttarakhand were collected, and Latent Class Cluster Analysis was performed for clinical profiling. ELISA was performed for DENV and CHIKV. 279 cases were enrolled, out of which 222 (79.5%) came positive for dengue NS1 Ag, 143 (51.2%) for dengue IgM, 98 (35.1%) for IgG followed by 16 (5.7%) of CHIKV IgM, and 4 (1.4%) were NS1 Ag with CHIKV IgM. Among the clinical features, fever (n = 270, 96.8%) was the most common symptom in all suspected dengue and chikungunya cases. Other symptoms like chills (n = 254, 91.0%), arthralgia (n = 241, 86.4%), and headache (n = 240, 86.0%) were present in a significant number. Results showed fewer odds of getting both DENV and CHIKV infection simultaneously, but the risk is still not negligible. This study explores the clinical presentation of the suspected dengue-chikungunya case. The increasing incidence of dengue and chikungunya and their co-infection necessitate the authorities' active surveillance of endemic regions and effective patient care management.

Contrasting the Practices of Virus Isolation and Characterization between the Early Period in History and Modern Times: The Case of Japanese Encephalitis Virus

Japanese encephalitis is a serious disease transmitted by mosquitoes. With its recent spread beyond the traditional territory of endemicity in Asia, the magnitude of global threat has increased sharply. While much of the current research are largely focused on changing epidemiology, molecular genetics of virus, and vaccination, little attention has been paid to the early history of virus isolation and phenotypic characterization of this virus. In this review, using this piece of history as an example, I review the transition of the concept and practice of virus isolation and characterization from the early period of history to modern times. The spectacular development of molecular techniques in modern times has brought many changes in practices as well as enormous amount of new knowledge. However, many aspects of virus characterization, in particular, transmission mechanism and host relationship, remain unsolved. As molecular techniques are not perfect in all respects, beneficial accommodation of molecular and biologic data is critically important in many branches of research. Accordingly, I emphasize exercising caution in applying only these modern techniques, point out unrecognized communication problems, and stress that JE research history is a rich source of interesting works still valuable even today and waiting to be discovered.

Co-circulation of alpha- and beta-coronaviruses in Pteropus vampyrus flying foxes from Indonesia

Bats are important reservoirs for alpha- and beta-coronaviruses. Coronaviruses (CoV) have been detected in pteropodid bats from several Southeast Asian countries, but little is known about coronaviruses in the Indonesian archipelago in proportion to its mammalian biodiversity. In this study, we screened pooled faecal samples from the Indonesian colonies of Pteropus vampyrus with unbiased next-generation sequencing. Bat CoVs related to Rousettus leschenaultii CoV HKU9 and Eidolon helvum CoV were detected. The 121 faecal samples were further screened using a conventional hemi-nested pan-coronavirus PCR assay. Three positive samples were successfully sequenced, and phylogenetic reconstruction revealed the presence of alpha- and beta-coronaviruses. CoVs belonging to the subgenera Nobecovirus, Decacovirus and Pedacovirus were detected in a single P. vampyrus roost. This study expands current knowledge of coronavirus diversity in Indonesian flying foxes, highlighting the need for longitudinal surveillance of colonies as continuing urbanization and deforestation heighten the risk of spillover events.

A validated triplex RT-qPCR protocol to simultaneously detect chikungunya, dengue and Zika viruses in mosquitoes

BACKGROUND & OBJECTIVES

Recently, the incidences of chikungunya, dengue and Zika infections have increased due to globalization and urbanization. It is vital that reliable detection tools become available to assess the viral prevalence within mosquito populations.

METHODS

Based on the previous publications on clinical diagnosis in human infections, for the first time, we described a customized triplex RT-qPCR protocol for simultaneous detection of chikungunya virus (CHIKV), dengue virus serotypes 1-4 (DENV1-4) and Zika virus (ZIKV) in mosquitoes.

RESULTS

In preliminary assessment to determine the specificity and sensitivity of primers and probes, all six targets were detected individually with the following thresholds as indicated by calculated pfu equivalents: 3.96x10⁰ for CHIKV, 3.80x10¹ for DENV1, 3.20x10¹ for DENV2, 8.00x10⁴ for DENV3, 1.58x10⁰ for DENV4, and 6.20x10⁰ for ZIKV When tested in a full combination of six targets (CDZ mix), CHIKV, DENV1-4 mix or ZIKV were all detected with the thresholds of 1.32x10⁰ for CHIKV, 3.79x10⁰ for DENV1-4 and 2.06x10⁰ for ZIKV All targets, individually or in full combination were detected in the mixtures of Aedes aegypti (L.) homogenate and viral lysates. A robust evaluation with three replicates in each of three plates for CHIKV, DENV1-4 and ZIKV individually or in full combination was conducted. In individual assays, CHIKV was detected to 3.96x10^-1, DENV1-4 to 1.14x10⁰ and ZIKV to 3.20x10⁰. In full combination assays, CHIKV was detected to 1.32x10⁴, DENV1-4 to 3.79x10¹ and ZIKV to 1.07x10⁰.

INTERPRETATION & CONCLUSION

This triplex RT-qPCR assay appears to consistently detect all six targets and does not cross react with Ae. aegypti homogenate, making it a feasible, practical, and immediately adoptable protocol for use among vector control and other entities, particularly in the endemic areas of CHIKV, DENVs and ZIKV.

Anti-chikungunya virus seroprevalence in Indigenous groups in the São Francisco Valley, Brazil

Background

Chikungunya fever (CHIKF) is a serious public health problem with a high rate of infection and chronic disabling manifestations that has affected more than 2 million people worldwide since 2005. In spite of this, epidemiological data on vulnerable groups such as Indigenous people are scarce, making it difficult to implement public policies in order to prevent this disease and assist these populations.

Objective

To describe the serological and epidemiological profile of chikungunya virus (CHIKV) in two Indigenous populations in Northeast Brazil, as well as in an urbanized control community, and to explore associations between CHIKV and anthropometric variables in these populations.

Methodology/Principal findings

This is a cross-sectional ancillary study of the Project of Atherosclerosis among Indigenous Populations (PAI) that included people 30 to 70 years old, recruited from two Indigenous tribes (the less urbanized Fulni-ô and the more urbanized Truká people) and an urbanized non-Indigenous control group from the same area. Subjects underwent clinical evaluation and were tested for anti-CHIKV IgG by enzyme-linked immunosorbent assay. Serological profile was described according to ethnicity, sex, and age. The study population included 433 individuals distributed as follows: 109 (25·2%) Truká, 272 (62·8%) Fulni-ô, and 52 (12%) from the non-Indigenous urbanized control group. Overall prevalence of CHIKV IgG in the study sample was 49.9% (216; 95% CI: 45·1–54·7). When the sample was stratified, positive CHIKV IgG was distributed as follows: no individuals in the Truká group, 78·3% (213/272; 95% CI: 72·9–83·1) in the Fulni-ô group, and 5.8% (3/52; 95% CI: 1.21–16) in the control group.

Conclusions/Significance

Positive tests for CHIKV showed a very high prevalence in a traditional Indigenous population, in contrast to the absence of anti-CHIKV serology in the Truká people, who are more urbanized with respect to physical landscape, socio-cultural, and historical aspects, as well as a low prevalence in the non-Indigenous control group, although all groups are located in the same area.

Chikungunya fever is a serious public health problem, with a high rate of infection and disease. Chikungunya virus (CHIKV) is a cosmopolitan virus, which has inflicted severe damage in 50 countries in the Americas and is responsible for chronic disabling manifestations. In spite of this, epidemiological data on vulnerable groups such as Indigenous people are scarce. We report on a cross-sectional study describing the seroprevalence of CHIKV in Indigenous groups in the São Francisco Valley, Brazil, in association with anthropometric data. The study population included 433 individuals distributed in the following ethnic groups: 109 (25.2%) Truká, 272 (62·8%) Fulni-ô, and 52 (12%) from the non-Indigenous urbanized control group When the sample was stratified, positive CHIKV IgG was distributed as follows: no individuals in the Truká group, 213/272 (78.3%; 95% CI: 72·9–83·1) individuals in the Fulni-ô group, and 3/52 (5.8%; 95% CI: 1·21–16) individuals in the control group. This study shows, for the first time, that CHIKV circulated in an Indigenous population (Fulni-ô) in the São Francisco Valley, in 2016 and 2017. The finding strikingly differs from the absence of anti-CHIKV serology found in the Truká people and from the low prevalence in the urban region of Juazeiro, Bahia.

Clinical Manifestations of Nipah Virus-Infected Patients Who Presented to the Emergency Department During an Outbreak in Kerala State in India, May 2018

BACKGROUND

An outbreak of Nipah virus (NiV) disease occurred in the Kozhikode district of Kerala State in India in May 2018. Several cases were treated at the emergency medicine department (ED) of the Government Medical College, Kozhikode (GMCK). The clinical manifestations and outcome of these cases are described.

METHODS

The study included 12 cases treated in the ED of GMCK. Detailed clinical examination, laboratory investigations, and molecular testing for etiological diagnosis were performed.

RESULTS

The median age of the patients was 30 years and the male to female ratio was 1.4:1.0. All the cases except the index case contracted the infection from hospitals. The median incubation period was 10 days, and the case fatality ratio was 83.3%. Ten (83.3%) patients had encephalitis and 9 out of 11 patients whose chest X-rays were obtained had bilateral infiltrates. Three patients had bradycardia and intractable hypotension requiring inotropes. Encephalitis, acute respiratory distress syndrome, and myocarditis were the clinical prototypes, but there were large overlaps between these. Ribavirin therapy was given to a subset of the patients. Although there was a 20% reduction in NiV encephalitis cases treated with the drug, the difference was not statistically significant. The outbreak ended soon after the introduction of total isolation of patients and barrier nursing.

CONCLUSION

The outbreak of NiV disease in Kozhikode in May 2018 presented as encephalitis, acute respiratory distress and myocarditis or combinations of these. The CFR was high. Ribavirin therapy was tried but no evidence for its benefit could be obtained.

Neurologic Manifestations of the World Health Organization's List of Pandemic and Epidemic Diseases

The World Health Organization (WHO) monitors the spread of diseases globally and maintains a list of diseases with epidemic or pandemic potential. Currently listed diseases include Chikungunya, cholera, Crimean-Congo hemorrhagic fever, Ebola virus disease, Hendra virus infection, influenza, Lassa fever, Marburg virus disease, Neisseria meningitis, MERS-CoV, monkeypox, Nipah virus infection, novel coronavirus (COVID-19), plague, Rift Valley fever, SARS, smallpox, tularemia, yellow fever, and Zika virus disease. The associated pathogens are increasingly important on the global stage. The majority of these diseases have neurological manifestations. Those with less frequent neurological manifestations may also have important consequences. This is highlighted now in particular through the ongoing COVID-19 pandemic and reinforces that pathogens with the potential to spread rapidly and widely, in spite of concerted global efforts, may affect the nervous system. We searched the scientific literature, dating from 1934 to August 2020, to compile data on the cause, epidemiology, clinical presentation, neuroimaging features, and treatment of each of the diseases of epidemic or pandemic potential as viewed through a neurologist's lens. We included articles with an abstract or full text in English in this topical and scoping review. Diseases with epidemic and pandemic potential can be spread directly from human to human, animal to human, via mosquitoes or other insects, or via environmental contamination. Manifestations include central neurologic conditions (meningitis, encephalitis, intraparenchymal hemorrhage, seizures), peripheral and cranial nerve syndromes (sensory neuropathy, sensorineural hearing loss, ophthalmoplegia), post-infectious syndromes (acute inflammatory polyneuropathy), and congenital syndromes (fetal microcephaly), among others. Some diseases have not been well-characterized from a neurological standpoint, but all have at least scattered case reports of neurological features. Some of the diseases have curative treatments available while in other cases, supportive care remains the only management option. Regardless of the pathogen, prompt, and aggressive measures to control the spread of these agents are the most important factors in lowering the overall morbidity and mortality they can cause.

Effect of Lockdown Measures on Atmospheric Nitrogen Dioxide during SARS-CoV-2 in Spain

The disease caused by SARS-CoV-2 has affected many countries and regions. In order to contain the spread of infection, many countries have adopted lockdown measures. As a result, SARS-CoV-2 has negatively influenced economies on a global scale and has caused a significant impact on the environment. In this study, changes in the concentration of the pollutant Nitrogen Dioxide (NO2) within the lockdown period were examined as well as how these changes relate to the Spanish population. NO2 is one of the reactive nitrogen oxides gases resulting from both anthropogenic and natural processes. One major source in urban areas is the combustion of fossil fuels from vehicles and industrial plants, both of which significantly contribute to air pollution. The long-term exposure to NO2 can also cause severe health problems. Remote sensing is a useful tool to analyze spatial variability of air quality. For this purpose, Sentinel-5P images registered from January to April of 2019 and 2020 were used to analyze spatial distribution of NO2 and its evolution under the lockdown measures in Spain. The results indicate a significant correlation between the population’s activity level and the reduction of NO2 values.

Coinfection of chikungunya and dengue viruses: A serological study from North Western region of Punjab, India

INTRODUCTION:

Dengue and chikungunya (CHIK) infections appear to be increasing in all parts of India. Aedes aegypti mosquitoes are common vectors for dengue virus (DENV) and CHIK virus (CHIKV). In areas where both viruses cocirculate, they can be transmitted together. There are very few studies discussing the dengue-chik coinfection from Punjab region of India. The present study was undertaken to study the clinical features of dengue–CHIK coinfection and compare with monoinfection.

MATERIALS AND METHODS:

IgM antibody capture (MAC) ELISA for dengue IgM and CHIK IgM and ELISA for nonstructural protein 1 antigen was performed on serum samples obtained from suspected patients.

RESULTS:

Out of total 3160 samples from suspected patients for dengue infection, 2178 (68.92%) samples were positive for DENV while CHIK IgM antibodies were positive in 127 patients out of the total suspected 373 cases (34.04%). In addition to this, 283 samples were tested for both viruses, out of which 27 sera were positive (9.54%) for coinfection of dengue and CHIK. The comparison of signs and symptoms showed that the coinfected patients had fever in all cases while rash was seen in only 30% cases. Arthralgia (79%) and thrombocytopenia (77%) was seen in significant number of coinfected cases thus revealing overlapping nature of dengue–CHIK coinfection.

CONCLUSION:

Increase in the number of Dengue and Chikungunya infections and their cocirculation is an important public health concern which warrants the implementation of strict control measures.

Viral engagement with host receptors blocked by a novel class of tryptophan dendrimers that targets the 5-fold-axis of the enterovirus-A71 capsid

Enterovirus A71 (EV-A71) is a non-polio neurotropic enterovirus with pandemic potential. There are no antiviral agents approved to prevent or treat EV-A71 infections. We here report on the molecular mechanism by which a novel class of tryptophan dendrimers inhibits (at low nanomolar to high picomolar concentration) EV-A71 replication in vitro. A lead compound in the series (MADAL385) prevents binding and internalization of the virus but does not, unlike classical capsid binders, stabilize the particle. By means of resistance selection, reverse genetics and cryo-EM, we map the binding region of MADAL385 to the 5-fold vertex of the viral capsid and demonstrate that a single molecule binds to each vertex. By interacting with this region, MADAL385 prevents the interaction of the virus with its cellular receptors PSGL1 and heparan sulfate, thereby blocking the attachment of EV-A71 to the host cells.

Enterovirus A71 (EV-A71) is the virus responsible for most of the severe forms of hand, foot and mouth disease (HFMD) associated with neurological involvement and mortality in young children under the age of 5. Seasonal outbreaks of HFMD -with a 2–3 years epidemic cycle- are recurring around the world, especially in the Asia-Pacific region. To date, no antiviral agent has been approved for the treatment of EV-A71 infections. Here, we report on a recently uncovered class of tryptophan dendrimers with an extraordinary antiviral activity in vitro against circulating EV-A71 clinical isolates. Mode of action studies revealed that this class of compounds targets the 5-fold vertex of EV-A71, in turn blocking receptor binding. Our finding may open an entirely novel line of research and largely aid in anti-enterovirus drug development.

Mapping the potential distributions of etiological agent, vectors, and reservoirs of Japanese Encephalitis in Asia and Australia

Japanese encephalitis virus (JEV) is a substantial cause of viral encephalitis, morbidity, and mortality in South-East Asia and the Western Pacific. World Health Organization recognized Japanese Encephalitis (JE) as a public health priority in demands to initiate active vaccination programs. Recently, the geographic distribution of JEV has apparently expanded into other areas in the Pacific islands and northern Australia; however, major gaps exist in knowledge in regard to its current distribution. Here, we mapped the potential distribution of mosquito vectors of JEV (Culex tritaeniorhynchus, Cx. pseudovishnui, Cx. vishnui, Cx. fuscocephala, Cx. gelidus), and reservoirs (Egretta garzetta, E. intermedia, Nycticorax nycticorax) based on ecological niche modeling approach. Ecological niche models predicted all species to occur across Central, South and South East Asia; however, Cx. tritaeniorhynchus, E. garzetta, E. intermedia, and N. nycticorax had broader potential distributions extending west to parts of the Arabian Peninsula. All predictions were robust and significantly better than random (P < 0.001). We also tested the JEV prediction based on 4335 additional independent human case records collected by the Chinese Information System for Disease Control and Prevention (CISDCP); 4075 cases were successfully predicted by the model (P < 0.001). Finally, we tested the ecological niche similarity among JEV, vector, and reservoir species and could not reject any of the null hypotheses of niche similarity in all combination pairs.

The Killer Virus Called Nipah: A Review

Nipah virus (NiV) is a deadly virus with a high mortality rate that has affected many developing countries in the past. According to the Centers for Disease Control and Prevention (CDC), many economically deprived countries such as Madagascar, Cambodia, and Thailand are also at high risk for future outbreaks. The first case of NiV was reported in 1998 and almost two decades later, little scientific progress has been made in finding a proper treatment and prevention vaccine. As many developing countries are not properly equipped to fight the infection, it is vital to properly educate the health systems. The aim of this review is to provide an epidemiological background as well as to understand the transmission routes, presentation, and the diagnosis and prevention of this deadly virus.

Chikungunya Detection during Dengue Outbreak in Sumatra, Indonesia: Clinical Manifestations and Virological Profile

Chikungunya fever (CHIK) is an acute viral infection caused by infection with chikungunya virus (CHIKV). The disease affects people in areas where certain Aedes species mosquito vectors are present, especially in tropical and subtropical countries. Indonesia has witnessed CHIK disease since the early 1970s with sporadic outbreaks occurring throughout the year. The CHIK clinical manifestation, characterized by fever, headache, and joint pain, is similar to that of dengue (DEN) disease. During a molecular study of a DEN outbreak in Jambi, Sumatra, in early 2015, DENV-negative samples were evaluated for evidence of CHIKV infection. Among 103 DENV-negative samples, eight samples were confirmed (7.8%) as positive for CHIKV by both molecular detection and virus isolation. The mean age of the CHIK patients was 21.3 ± 9.1 (range 11-35 years). The clinical manifestations of the CHIK patients were mild and mimicked DEN, with fever and headache as the main symptoms. Only three out of eight patients presented with classical joint pain. Sequencing of the envelope glycoprotein E1 gene and phylogenetic analysis identified all CHIKV isolates as belonging to the Asian genotype. Overall, our study confirms sustained endemic CHIKV transmission and the presence of multiple arboviruses circulating during a DEN outbreak in Indonesia. The co-circulation of arboviruses poses a public health threat and is likely to cause misdiagnosis and underreporting of CHIK in DEN-endemic areas such as Indonesia.

Persistence of Zika virus in conjunctival fluid of convalescence patients

A widespread epidemic of Zika fever, caused by Zika virus (ZIKAV) has spread throughout the Pacific islands, the Americas and Southeast Asia. The increased incidences of ocular anomalies observed in ZIKAV-infected infants and adults may be associated with the rapid spread of ZIKAV. The objective of this study was to check if ZIKAV could be detected in human tears after the first week of infection. Twenty-nine patients with PCR confirmed ZIKAV infection during the Singapore August 2016 ZIKAV outbreak were enrolled for the study. Detection and quantification of ZIKAV RNA was performed on conjunctival swabs collected from both eyes of these patients at the late convalescent phase (30 days post-illness). Efficiency of viral isolation from swab samples was confirmed by the limit of detection (as low as 0.1 PFU/µL, equivalent to copy number of 4.9) in spiked swabs with different concentrations of ZIKAV (PFU/µL). Samples from three patients were found positive by qRT-PCR for ZIKAV and the viral RNA copy numbers detected in conjunctival swabs ranged from 5.2 to 9.3 copies respectively. ZIKAV could persist in the tears of infected patients for up to 30 days post-illness, and may therefore possess a potential public health risk of transmission.

Co-Infection of Mosquitoes with Chikungunya and Dengue Viruses Reveals Modulation of the Replication of Both Viruses in Midguts and Salivary Glands of Aedes aegypti Mosquitoes

Arthropod-borne virus (arbovirus) infections cause several emerging and resurgent infectious diseases in humans and animals. Chikungunya-affected areas often overlap with dengue-endemic areas. Concurrent dengue virus (DENV) and chikungunya virus (CHIKV) infections have been detected in travelers returning from regions of endemicity. CHIKV and DENV co-infected Aedes albopictus have also been collected in the vicinity of co-infected human cases, emphasizing the need to study co-infections in mosquitoes. We thus aimed to study the pathogen-pathogen interaction involved in these co-infections in DENV/CHIKV co-infected Aedes aegypti mosquitoes. In mono-infections, we detected CHIKV antigens as early as 4 days post-virus exposure in both the midgut (MG) and salivary gland (SG), whereas we detected DENV serotype 2 (DENV-2) antigens from day 5 post-virus exposure in MG and day 10 post-virus exposure in SG. Identical infection rates were observed for singly and co-infected mosquitoes, and facilitation of the replication of both viruses at various times post-viral exposure. We observed a higher replication for DENV-2 in SG of co-infected mosquitoes. We showed that mixed CHIKV and DENV infection facilitated viral replication in Ae. aegypti. The outcome of these mixed infections must be further studied to increase our understanding of pathogen-pathogen interactions in host cells.

Chikungunya virus: an update on the biology and pathogenesis of this emerging pathogen

Re-emergence of chikungunya virus, a mosquito-transmitted pathogen, is of serious public health concern. In the past 15 years, after decades of infrequent, sporadic outbreaks, the virus has caused major epidemic outbreaks in Africa, Asia, the Indian Ocean, and more recently the Caribbean and the Americas. Chikungunya virus is mainly transmitted by Aedes aegypti mosquitoes in tropical and subtropical regions, but the potential exists for further spread because of genetic adaptation of the virus to Aedes albopictus, a species that thrives in temperate regions. Chikungunya virus represents a substantial health burden to affected populations, with symptoms that include severe joint and muscle pain, rashes, and fever, as well as prolonged periods of disability in some patients. The inflammatory response coincides with raised levels of immune mediators and infiltration of immune cells into infected joints and surrounding tissues. Animal models have provided insights into disease pathology and immune responses. Although host innate and adaptive responses have a role in viral clearance and protection, they can also contribute to virus-induced immune pathology. Understanding the mechanisms of host immune responses is essential for the development of treatments and vaccines. Inhibitory compounds targeting key inflammatory pathways, as well as attenuated virus vaccines, have shown some success in animal models, including an attenuated vaccine strain based on an isolate from La Reunion incorporating an internal ribosome entry sequence that prevents the virus from infecting mosquitoes and a vaccine based on virus-like particles expressing envelope proteins. However, immune correlates of protection, as well as the safety of prophylactic and therapeutic candidates, are important to consider for their application in chikungunya infections. In this Review, we provide an update on chikungunya virus with regard to its epidemiology, molecular virology, virus-host interactions, immunological responses, animal models, and potential antiviral therapies and vaccines.

Development and characterization of microsatellite markers for the oomyceta Aphanomyces euteiches

Aphanomyces euteiches Drechsler is a serious pathogen of leguminous crops that causes devastating root rot of pea worldwide. Given that A. euteiches is a diploid organism, robust, codominant markers are needed for population genetics studies. We have developed and screened a microsatellite-enriched small-insert genomic library for identification of A. euteiches SSR containing sequences. Fourteen out of the 48 primer pairs designed to amplify SSR, produced unambiguous polymorphic products in our test population of 94 isolates. The number of alleles at each locus ranged from one to four. The identification of new markers would enhance the ability to evaluate the genetic structure of A. euteiches populations, and pathogen evolution.

Re-evaluating the residual risk of transfusion-transmitted Ross River virus infection

BACKGROUND AND OBJECTIVES

Ross River virus (RRV) is an enveloped, RNA alphavirus in the same antigenic group as chikungunya virus. Australia records an annual average of 5000 laboratory-confirmed RRV infections. While RRV is currently geographically restricted to the Western Pacific, the capacity of arboviruses for rapid expansion is well established. The first case of RRV transfusion-transmission was recently described prompting a comprehensive risk assessment.

MATERIALS AND METHODS

To estimate the RRV residual risk, we applied laboratory-confirmed RRV notifications to two published models. This modelling generated point estimates for the risk of viraemia in the donor population, the risk of collecting a viraemic donation and the predicted number of infected components.

RESULTS

The EUFRAT model estimated the risk of infection in donors as one in 95 039 (one in 311 328 to one in 32 399) to one in 14 943 (one in 48 593 to one in 5094). The point estimate for collecting a RRV viraemic donation varied from one in 166 486 (one in 659 078 to one in 49 158) (annualized national risk) to one in 26 117 (one in 103 628 to one in 7729) (area of high transmission). The modelling predicted 8-11 RRV-infected labile blood components issued in Australia during a 1-year period.

CONCLUSION

Considering the uncertainty in the modelled estimates, the unknown rate of RRV donor viraemia and the low severity of any recipient RRV infection, additional risk management for RRV in Australia will initially be restricted to strengthening the messaging to donors regarding prompt reporting of any postdonation illnesses.

The Role of Bats as Reservoir Hosts of Emerging Neuroviruses

Recent studies have clearly shown that bats are the reservoir hosts of a wide diversity of novel viruses with representatives from most of the known animal virus families. In many respects bats make ideal reservoir hosts for viruses: they are the only mammals that fly, thus assisting in virus dispersal; they roost in large numbers, thus aiding transmission cycles; some bats hibernate over winter, thus providing a mechanism for viruses to persist between seasons; and genetic factors may play a role in the ability of bats to host viruses without resulting in clinical disease. Within the broad diversity of viruses found in bats are some important neurological pathogens, including rabies and other lyssaviruses, and Hendra and Nipah viruses, two recently described viruses that have been placed in a new genus, Henipaviruses in the family Paramyxoviridae. In addition, bats can also act as alternative hosts for the flaviviruses Japanese encephalitis and St Louis encephalitis viruses, two important mosquito-borne encephalitogenic viruses, and bats can assist in the dispersal and over-wintering of these viruses. Bats are also the reservoir hosts of progenitors of SARS and MERS coronaviruses, although other animals act as spillover hosts. This chapter presents the physiological and ecological factors affecting the ability of bats to act as reservoirs of neurotropic viruses, and describes the major transmission cycles leading to human infection.

Chikungunya Virus Infections Among Patients with Dengue-Like Illness at a Tertiary Care Hospital in the Philippines, 2012-2013

Chikungunya virus (CHIKV) often co-circulates with dengue virus (DENV). A cross-sectional surveillance study was conducted at a tertiary hospital in Manila, Philippines, to describe the prevalence and characteristics of DENV and CHIKV infections among patients seeking care for dengue-like illness. Acute blood samples from patients ≥ 6 months of age clinically diagnosed with dengue from November 2012 to December 2013 underwent reverse transcription polymerase chain reaction (RT-PCR) to detect DENV and CHIKV RNA. A total of 118 patients with clinically diagnosed dengue (age range = 1-89 years, mean = 22 years; male-to-female ratio = 1.51) were tested by DENV RT-PCR; 40 (34%) were DENV PCR-positive (age range = 1-45 years, mean = 17 years). All DENV serotypes were detected: 11 (28%) DENV-1, 6 (15%) DENV-2, 6 (15%) DENV-3, and 17 (42%) DENV-4. Of 112 patients clinically diagnosed with dengue and tested by CHIKV RT-PCR, 11 (10%) were CHIKV PCR-positive (age range = 2-47 years, mean = 20.3 years). No coinfections were detected. Presenting signs/symptoms did not differ between DENV- and CHIKV-positive cases. Sequencing of envelope 1 gene from two CHIKV PCR-positive samples showed Asian genotype. This study highlights the potential for misdiagnosis of medically attended CHIKV infections as DENV infection and the difficulty in clinically differentiating dengue and chikungunya based on presenting signs/symptoms alone. This underscores the necessity for diagnostic laboratory tests to distinguish CHIKV infections in the background of actively co-circulating DENV.

Immunity and clinical efficacy of an inactivated enterovirus 71 vaccine in healthy Chinese children: a report of further observations

BACKGROUND

To investigate the long-term effects on immunity of an inactivated enterovirus 71 (EV71) vaccine and its protective efficacy.

METHODS

A sub-cohort of 1,100 volunteers from Guangxi Province in China was eligible for enrolment and randomly administered either the EV71 vaccine or a placebo on days 0 and 28 in a phase III clinical trial and then observed for the following 2 years with approval by an independent ethics committee of Guangxi Zhuang Autonomous Region, China. Serum samples from the 350 participants who provided a full series of blood samples (at all the sampling points) within the 2-year period were collected. Vaccine-induced immune effects, including the neutralizing antibody titres and cross-protection against different genotypes of EV71, were examined. This study also evaluated the protective efficacy of this vaccine based upon clinical diagnosis.

RESULTS

This sub-cohort showed a >60% drop-out rate over 2 years. The seroconversion rates among the 161 immunized subjects remained >95% at the end of study. The geometric mean titres of neutralizing antibodies (anti-genotype C4) 360 days after vaccination in 350 subjects were 81.0 (subjects aged 6-11 months), 98.4 (12-23 months), 95.0 (24-35 months), and 81.8 (36-71 months). These titres subsequently increased to 423.1, 659.0, 545.0, and 321.9, respectively, at 540 days post-immunization (d.p.i.), and similar levels were maintained at 720 d.p.i. Higher IFN-γ/IL-4-specific responses to the C4 genotype of EV71 and cross-neutralization reactivity against major EV71 genotype strains were observed in the vaccine group compared to those in the placebo group. Five EV71-infected subjects were observed in the placebo-treated control group and none in the vaccine-immunized group in per-protocol analysis.

CONCLUSION

These results are consistent with the induction of dynamic immune responses and protective efficacy of the vaccine against most circulating EV71 strains.

TRIAL REGISTRATION NUMBER

Clinicaltrials.gov, NCT01569581, Trial registration date: March 2012.

An Outbreak of Chikungunya in Rural Bangladesh, 2011

BACKGROUND

The first identified Chikungunya outbreak occurred in Bangladesh in 2008. In late October 2011, a local health official from Dohar Sub-district, Dhaka District, reported an outbreak of undiagnosed fever and joint pain. We investigated the outbreak to confirm the etiology, describe the clinical presentation, and identify associated vectors.

METHODOLOGY

During November 2-21, 2011, we conducted house-to-house surveys to identify suspected cases, defined as any inhabitant of Char Kushai village with fever followed by joint pain in the extremities with onset since August 15, 2011. We collected blood specimens and clinical histories from self-selected suspected cases using a structured questionnaire. Blood samples were tested for IgM antibodies against Chikungunya virus. The village was divided into nine segments and we collected mosquito larvae from water containers in seven randomly selected houses in each segment. We calculated the Breteau index for the village and identified the mosquito species.

RESULTS

The attack rate was 29% (1105/3840) and 29% of households surveyed had at least one suspected case: 15% had ≥3. The attack rate was 38% (606/1589) in adult women and 25% in adult men (320/1287). Among the 1105 suspected case-patients, 245 self-selected for testing and 80% of those (196/245) had IgM antibodies. In addition to fever and joint pain, 76% (148/196) of confirmed cases had rash and 38%(75/196) had long-lasting joint pain. The village Breteau index was 35 per 100 and 89%(449/504) of hatched mosquitoes were Aedes albopictus.

CONCLUSION

The evidence suggests that this outbreak was due to Chikungunya. The high attack rate suggests that the infection was new to this area, and the increased risk among adult women suggests that risk of transmission may have been higher around households. Chikungunya is an emerging infection in Bangladesh and current surveillance and prevention strategies are insufficient to mount an effective public health response.

Diagnosis of Chikungunya dominated co-infection with dengue during an outbreak in south India (2010 and 2012)

Following a report of dengue outbreak from January 2010 to 2012 in the Tirunelveli, Theni, Dharmapuri and Thiruvallur districts of Tamil Nadu state, India, an investigation was carried out. The study was to demonstrate the probable presence of Chikungunya viral antibodies in patients clinically suspected of dengue fever. Out of 331 samples analysed, dengue viral antibodies were observed in 14.8% (n = 49) of patients, while 16.6% (n = 55) were positive for Chikungunya viral specific IgM antibodies. In the four districts surveyed, patients found positive for Chikungunya were found to be higher than dengue. The clinician should consider Chikungunya in the differential diagnosis of dengue-like infection appearing in the community.

Dynamics of Japanese encephalitis virus transmission among pigs in Northwest Bangladesh and the potential impact of pig vaccination

Background

Japanese encephalitis (JE) virus infection can cause severe disease in humans, resulting in death or permanent neurologic deficits among survivors. Studies indicate that the incidence of JE is high in northwestern Bangladesh. Pigs are amplifying hosts for JE virus (JEV) and a potentially important source of virus in the environment. The objectives of this study were to describe the transmission dynamics of JEV among pigs in northwestern Bangladesh and estimate the potential impact of vaccination to reduce incidence among pigs.

Methodology/Principal Findings

We conducted a comprehensive census of pigs in three JE endemic districts and tested a sample of them for evidence of previous JEV infection. We built a compartmental model to describe JEV transmission dynamics in this region and to estimate the potential impact of pig vaccination. We identified 11,364 pigs in the study area. Previous JEV infection was identified in 30% of pigs with no spatial differences in the proportion of pigs that were seropositive across the study area. We estimated that JEV infects 20% of susceptible pigs each year and the basic reproductive number among pigs was 1.2. The model suggest that vaccinating 50% of pigs each year resulted in an estimated 82% reduction in annual incidence in pigs.

Conclusions/Significance

The widespread distribution of historic JEV infection in pigs suggests they may play an important role in virus transmission in this area. Future studies are required to understand the contribution of pig infections to JE risk in humans and the potential impact of pig vaccination on human disease.

Japanese encephalitis (JE) virus infection can cause severe neurological disease in man. More JE cases are seen in northwestern districts in Bangladesh. Pigs are the most common amplifying host of the virus and can act as a potential environmental source. We conducted a comprehensive census of pigs in three JE endemic districts and tested a sample of them for evidence of previous JEV infection. We built a compartmental model to describe JEV transmission dynamics in this region and to estimate the potential impact of pig vaccination. We identified 11,364 pigs in our study area, mostly raised in backyards. About 30% of the pigs had evidence of previous JE virus infection. Our model suggests that vaccinating 50% of pigs each year resulted in an estimated 82% reduction in annual incidence in pigs. Pigs in northwestern Bangladesh may play a significant role in JE virus transmission. JE incidence may be substantially reduced through reasonable pig vaccination coverage.

A model for a chikungunya outbreak in a rural Cambodian setting: implications for disease control in uninfected areas

Following almost 30 years of relative silence, chikungunya fever reemerged in Kenya in 2004. It subsequently spread to the islands of the Indian Ocean, reaching Southeast Asia in 2006. The virus was first detected in Cambodia in 2011 and a large outbreak occurred in the village of Trapeang Roka Kampong Speu Province in March 2012, in which 44% of the villagers had a recent infection biologically confirmed. The epidemic curve was constructed from the number of biologically-confirmed CHIKV cases per day determined from the date of fever onset, which was self-reported during a data collection campaign conducted in the village after the outbreak. All individuals participating in the campaign had infections confirmed by laboratory analysis, allowing for the identification of asymptomatic cases and those with an unreported date of fever onset. We develop a stochastic model explicitly including such cases, all of whom do not appear on the epidemic curve. We estimate the basic reproduction number of the outbreak to be 6.46 (95% C.I. [6.24, 6.78]). We show that this estimate is particularly sensitive to changes in the biting rate and mosquito longevity. Our model also indicates that the infection was more widespread within the population on the reported epidemic start date. We show that the exclusion of asymptomatic cases and cases with undocumented onset dates can lead to an underestimation of the reproduction number which, in turn, could negatively impact control strategies implemented by public health authorities. We highlight the need for properly documenting newly emerging pathogens in immunologically naive populations and the importance of identifying the route of disease introduction.

During the recent resurgence of chikungunya, the scale of imported cases into previously unaffected countries has caused great concern due to the presence of a competent vector (Aedes albopictus) in many of these regions. This study describes a mathematical model for a chikungunya outbreak in the rural Cambodian village of Trapeang Roka, where a chikungunya epidemic was recorded and documented in March 2012. The outbreak data is unique, in that all infections were confirmed by laboratory analysis, enabling the identification of asymptomatic individuals, in addition to individuals who failed to report details of their infection. A stochastic model, partitioning the infectious population into three distinct classes, is implemented using Gillespie's algorithm. We show that the incorporation of both biologically-confirmed symptomatic cases undocumented by date of fever onset and asymptomatic cases yields a higher estimate of the reproduction number. Our results highlight how reproduction numbers could be underestimated by limiting analysis to the epidemic curve. Carefully documenting cases and performing laboratory testing in cluster regions, such as the village considered here, could provide a more comprehensive insight into the true infection dynamics.

Augmented miR-150 expression associated with depressed SOCS1 expression involved in dengue haemorrhagic fever

OBJECTIVE

Suppressors of cytokine signalling (SOCS) proteins regulate cytokine responses and control immune balance. The objective of our study was to determine whether the expression of SOCS1 and its potential regulatory microRNAs (miRNAs) in leukocytes is correlated to the development of dengue haemorrhagic fever (DHF).

METHODS

We performed a case-control study to investigate the SOCS1 and miRNA expression in leukocytes for patients with DF and DHF in a DENV-2 outbreak that occurred in Taiwan between 2002 and 2003. We performed reverse transcription polymerase chain reaction to evaluate the expression of SOCS1 and its regulatory miRNAs in mononuclear leukocytes obtained from patients with or without DHF. The reciprocal relationship between SOCS1 and miR-150 expression was validated in DENV-2-infected peripheral mononuclear cells (PBMCs).

RESULTS

SOCS1 expression and lower IFN-γ level were significantly reduced in DHF patients, but not in patients with DF. Elevated SOCS1 and reduced miR-150 levels were detected 24 h after DENV-2 infection in PBMCs. Transfection of a miR-150 mimic into CD14(+) cells infected with DENV-2 suppressed the induction of SOCS1 expression in a dose-dependent manner.

CONCLUSION

We demonstrate for the first time that augmented miR-150 expression with depressed SOCS1 expression in CD14(+) cells are associated with the pathogenesis of DHF.

High level of vector competence of Aedes aegypti and Aedes albopictus from ten American countries as a crucial factor in the spread of Chikungunya virus

Chikungunya virus (CHIKV) causes a major public health problem. In 2004, CHIKV began an unprecedented global expansion and has been responsible for epidemics in Africa, Asia, islands in the Indian Ocean region, and surprisingly, in temperate regions, such as Europe. Intriguingly, no local transmission of chikungunya virus (CHIKV) had been reported in the Americas until recently, despite the presence of vectors and annually reported imported cases. Here, we assessed the vector competence of 35 American Aedes aegypti and Aedes albopictus mosquito populations for three CHIKV genotypes. We also compared the number of viral particles of different CHIKV strains in mosquito saliva at two different times postinfection. Primarily, viral dissemination rates were high for all mosquito populations irrespective of the tested CHIKV isolate. In contrast, differences in transmission efficiency (TE) were underlined in populations of both species through the Americas, suggesting the role of salivary glands in selecting CHIKV for highly efficient transmission. Nonetheless, both mosquito species were capable of transmitting all three CHIKV genotypes, and TE reached alarming rates as high as 83.3% and 96.7% in A. aegypti and A. albopictus populations, respectively. A. albopictus better transmitted the epidemic mutant strain CHIKV_0621 of the East-Central-South African (ECSA) genotype than did A. aegypti, whereas the latter species was more capable of transmitting the original ECSA CHIKV_115 strain and also the Asian genotype CHIKV_NC. Therefore, a high risk of establishment and spread of CHIKV throughout the tropical, subtropical, and even temperate regions of the Americas is more real than ever.

IMPORTANCE

Until recently, the Americas had never reported chikungunya (CHIK) autochthonous transmission despite its global expansion beginning in 2004. Large regions of the continent are highly infested with Aedes aegypti and Aedes albopictus mosquitoes, and millions of dengue (DEN) cases are annually recorded. Indeed, DEN virus and CHIK virus (CHIKV) share the same vectors. Due to a recent CHIK outbreak affecting Caribbean islands, the need for a Pan-American evaluation of vector competence was compelling as a key parameter in assessing the epidemic risk. We demonstrated for the first time that A. aegypti and A. albopictus populations throughout the continent are highly competent to transmit CHIK irrespective of the viral genotypes tested. The risk of CHIK spreading throughout the tropical, subtropical, and even temperate regions of the Americas is more than ever a reality. In light of our results, local authorities should immediately pursue and reinforce epidemiological and entomological surveillance to avoid a severe epidemic.

Regional impact of climate on Japanese encephalitis in areas located near the three gorges dam

Background

In this study, we aim to identify key climatic factors that are associated with the transmission of Japanese encephalitis virus in areas located near the Three Gorges Dam, between 1997 and 2008.

Methods

We identified three geographical regions of Chongqing, based on their distance from the Three Gorges Dam. Collectively, the three regions consisted of 12 districts from which study information was collected. Zero-Inflated Poisson Regression models were run to identify key climatic factors of the transmission of Japanese encephalitis virus for both the whole study area and for each individual region; linear regression models were conducted to examine the fluctuation of climatic variables over time during the construction of the Three Gorges Dam.

Results

Between 1997 and 2008, the incidence of Japanese encephalitis decreased throughout the entire city of Chongqing, with noticeable variations taking place in 2000, 2001 and 2006. The eastern region, which is closest to the Three Gorges Dam, suffered the highest incidence of Japanese encephalitis, while the western region experienced the lowest incidence. Linear regression models revealed that there were seasonal fluctuations of climatic variables during this period. Zero-Inflated Poisson Regression models indicated a significant positive association between temperature (with a lag of 1 and 3 months) and Japanese encephalitis incidence, and a significant negative association between rainfall (with a lag of 0 and 4 months) and Japanese encephalitis incidence.

Conclusion

The spatial and temporal trends of Japanese encephalitis incidence that occurred in the City of Chongqing were associated with temperature and rainfall. Seasonal fluctuations of climatic variables during this period were also observed. Additional studies that focus on long-term data collection are needed to validate the findings of this study and to further explore the effects of the Three Gorges Dam on Japanese encephalitis and other related diseases.

Crimean-Congo Hemorrhagic Fever: Current Scenario in India

India is considered as a hot spot for emerging infectious diseases. In the recent past many infectious diseases of emerging and re-emerging nature have entered this subcontinent and affected a large number of populations. A few examples are Nipah, Avian influenza, Pandemic influenza, severe acute respiratory syndrome corona virus and Chikungunya virus. These diseases have not only affected human and animal health but also economy of the country on a very large scale. During December 2010, National Institute of Virology, Pune detected Crimean-Congo hemorrhagic fever virus specific IgG antibodies in livestock serum samples from Gujarat and Rajasthan states. Subsequently, during January 2011 Crimean-Congo hemorrhagic fever virus was confirmed in a nosocomial outbreak, in Ahmadabad, Gujarat, India. Retrospective investigation of suspected human samples confirmed that the virus was present in Gujarat state, earlier to this outbreak. This disease has a case fatality rate ranging from 5 to 80 %. Earlier presence of hemagglutination inhibition antibodies have been detected in animal sera from Jammu and Kashmir, the western border districts, southern regions and Maharashtra state of India. The evidences of virus activity and antibodies were observed during and after the outbreak in human beings, ticks and domestic animals (buffalo, cattle, goat and sheep) from Gujarat State of India. During the year 2012, this virus was again reported in human beings and animals. Phylogenetic analysis showed that all the four isolates of 2011, as well as the S segment from specimen of 2010 and 2012 were highly conserved and clustered together in the Asian/Middle East genotype IV. The S segment of South-Asia 2 type was closest to a Tajikistan strain TADJ/HU8966 of 1990. The present scenario in India suggests the need to look seriously into various important aspects of this zoonotic disease, which includes diagnosis, intervention, patient management, control of laboratory acquired and nosocomial infection, tick control, livestock survey and this, should be done in priority before it further spreads to other states. Being a high risk group pathogen, diagnosis is a major concern in India where only a few Biosafety level 3 laboratories exist and it needs to be addressed immediately before this disease becomes endemic in India.

Ecological Approaches to Studying Zoonoses

Concern over emerging infectious diseases (EIDs) and a better understanding of their causes has resulted in increasing recognition of the linkages among human, animal, and ecosystem health. It is now well recognized that human activities can promote the emergence of infectious diseases through the large-scale modification of natural environments and inadvertent vectoring (e.g., international trade and travel). These perturbations can alter the ecological and evolutionary relationships among humans, wildlife, and the pathogens that move between them, resulting in disease emergence. In recent years, the rise in zoonotic EIDs has not only increased our awareness of the need for cross-sectoral collaborations, but has also highlighted the disconnect between current ecological theory and biological reality. As the One Health movement continues to gain steam, further integration of ecological approaches into the One Health framework will be required. We discuss the importance of ecological methods and theory to the study of zoonotic diseases by (i) discussing key ecological concepts and approaches, (ii) reviewing methods of studying wildlife diseases and their potential applications for zoonoses, and (iii) identifying future directions in the One Health movement.

Recrudescent infection supports Hendra virus persistence in Australian flying-fox populations

Zoonoses from wildlife threaten global public health. Hendra virus is one of several zoonotic viral diseases that have recently emerged from Pteropus species fruit-bats (flying-foxes). Most hypotheses regarding persistence of Hendra virus within flying-fox populations emphasize horizontal transmission within local populations (colonies) via urine and other secretions, and transmission among colonies via migration. As an alternative hypothesis, we explore the role of recrudescence in persistence of Hendra virus in flying-fox populations via computer simulation using a model that integrates published information on the ecology of flying-foxes, and the ecology and epidemiology of Hendra virus. Simulated infection patterns agree with infection patterns observed in the field and suggest that Hendra virus could be maintained in an isolated flying-fox population indefinitely via periodic recrudescence in a manner indistinguishable from maintenance via periodic immigration of infected individuals. Further, post-recrudescence pulses of infectious flying-foxes provide a plausible basis for the observed seasonal clustering of equine cases. Correct understanding of the infection dynamics of Hendra virus in flying-foxes is fundamental to effectively managing risk of infection in horses and humans. Given the lack of clear empirical evidence on how the virus is maintained within populations, the role of recrudescence merits increased attention.

Perspectives of public health laboratories in emerging infectious diseases

The world has experienced an increased incidence and transboundary spread of emerging infectious diseases over the last four decades. We divided emerging infectious diseases into four categories, with subcategories in categories 1 and 4. The categorization was based on the nature and characteristics of pathogens or infectious agents causing the emerging infections, which are directly related to the mechanisms and patterns of infectious disease emergence. The factors or combinations of factors contributing to the emergence of these pathogens vary within each category. We also classified public health laboratories into three types based on function, namely, research, reference and analytical diagnostic laboratories, with the last category being subclassified into primary (community-based) public health and clinical (medical) analytical diagnostic laboratories. The frontline/leading and/or supportive roles to be adopted by each type of public health laboratory for optimal performance to establish the correct etiological agents causing the diseases or outbreaks vary with respect to each category of emerging infectious diseases. We emphasize the need, especially for an outbreak investigation, to establish a harmonized and coordinated national public health laboratory system that integrates different categories of public health laboratories within a country and that is closely linked to the national public health delivery system and regional and international high-end laboratories.

Serological survey of veterinarians to assess the zoonotic potential of three emerging swine diseases in Mexico

We conducted an immunological assay of blood samples taken from 85 swine-specialist veterinarians attending the Congress of the Mexican Association of Swine Specialist Veterinarians in Mexico in 2011. Serum samples were assayed for Porcine rubulavirus (PorPV), Encephalomyocarditis virus (EMCV) and Leptospira spp. antibodies. Using a hemagglutination inhibition test, we registered 2.3% and 27% seropositivity for PorPV and EMCV, respectively. Using viral neutralization tests, we registered 5.8% and 47% seropositivity for PorPV and EMCV, respectively. For Leptospira spp., we registered a seropositivity of 38.8%. The variables (sex, age, years of exposure, number of visited farms, biosecurity level and region) showed no significant effect (P > 0.05) on the seropositivity for EMCV, PorPV and Leptospira spp. except for number of visited farms on HI seropositivity for EMCV (P < 0.05; odds ratio: 1.38). The data obtained provide information on the epidemiology of emerging diseases with zoonotic potential in occupational risk groups.

Cooling off health security hot spots: getting on top of it down under

Australia is free of many diseases, pests and weeds found elsewhere in the world due to its geographical isolation and relatively good health security practices. However, its health security is under increasing pressure due to a number of ecological, climatic, demographic and behavioural changes occurring globally. North Queensland is a high risk area (a health security hot spot) for Australia, due in part to its connection to neighbouring countries via the Torres Strait and the Indo-Papuan conduit, its high diversity of wildlife reservoirs and its environmental characteristics. Major outbreaks of exotic diseases, pests and weeds in Australia can cost in excess of $1 billion; however, most expenditure on health security is reactive apart from preventive measures undertaken for a few high profile diseases, pests and weeds. Large gains in health security could therefore be made by spending more on pre-emptive approaches to reduce the risk of outbreaks, invasion/spread and establishment, despite these gains being difficult to quantify. Although biosecurity threats may initially have regional impacts (e.g. Hendra virus), a break down in security in health security hot spots can have national and international consequences, as has been seen recently in other regions with the emergence of SARS and pandemic avian influenza. Novel approaches should be driven by building research and management capacity, particularly in the regions where threats arise, a model that is applicable both in Australia and in other regions of the world that value and therefore aim to improve their strategies for maintaining health security.

Development and application of an indirect enzyme-linked immunosorbent assay for serological survey of Japanese encephalitis virus infection in dogs

Japanese encephalitis virus (JEV) causes serious acute encephalitis in humans and horses. Although dogs are good sentinels for assessing the risk of JEV infection to humans, a virus neutralization test has been the only method available for measuring the levels of JEV antibody in dogs. In this study, an indirect enzyme-linked immunosorbent assay (ELISA) using purified viral particles as an antigen, was developed for serological survey of JEV infection in dogs. In dogs inoculated experimentally with JEV, the ELISA detected anti-JEV IgM 3 days after infection, with IgM levels peaking 7 days after infection. Anti-JEV IgG was detected 14 days after infection and peaked on 21-28 days after infection. Virus neutralization titers correlated with anti-JEV immunoglobulins measured by the ELISA. To test the utility of the new assay, the seroprevalence of JEV infection among 102 dogs in Kyushu, Japan, was examined by IgG ELISA and by virus neutralization. The correlation coefficient between the IgG ELISA and virus neutralization was 0.813 (p<0.001); comparison of the IgG ELISA and virus neutralization showed a sensitivity and specificity of 82% and 98%, respectively. The IgG ELISA was used to survey dogs in Bangkok, Thailand and 51% of these dogs were found seropositive for JEV. These data suggest that in the capital city of Thailand, the risk of infection with JEV remains high.

Recent introduction and rapid dissemination of Chikungunya virus and Dengue virus serotype 2 associated with human and mosquito coinfections in Gabon, central Africa

BACKGROUND

Chikungunya virus (CHIKV) and Dengue virus serotype 2 (DENV-2) were recently introduced in central Africa, along with Aedes albopictus. Simultaneous outbreaks of CHIKV and DENV-2 have subsequently occurred, in Cameroon in 2006 and Gabon in 2007.

METHODS

To study the spread of the 2 viruses, we conducted active surveillance of acute febrile syndromes throughout Gabon between 2007 and 2010. Diagnostic methods included quantitative real-time reverse-transcription polymerase chain reaction, and molecular characterization was based on partial envelope gene sequences.

RESULTS

Between 2007 and 2010, 4287 acutely febrile patients were investigated for CHIKV and DENV-2 infections, of whom 1567 were CHIKV-positive, 376 DENV-2-positive, and 37 coinfected. We diagnosed 153 CHIKV and 11 DENV-2 cases in 2008, and 5 CHIKV and 9 DENV-2 cases in 2009. In 2010, CHIKV and DENV-2 caused a second large simultaneous outbreak. Among 2826 acutely febrile patients examined during this outbreak, 1112 were CHIKV-positive, 288 DENV-2-positive, and 28 coinfected. Mosquitoes were collected near the homes of coinfected patients, and 1 Aedes albopictus specimen was found to be positive for both CHIKV and DENV-2.

CONCLUSIONS

These findings show the rapid dissemination of CHIKV and DENV-2 within a nonimmune population in a tropical African country, probably facilitated by the spread of Aedes albopictus. This has resulted in major simultaneous outbreaks with numerous coinfections in both human and mosquito.

Chikungunya: a re-emerging virus

In the past decade, chikungunya--a virus transmitted by Aedes spp mosquitoes--has re-emerged in Africa, southern and southeastern Asia, and the Indian Ocean Islands as the cause of large outbreaks of human disease. The disease is characterised by fever, headache, myalgia, rash, and both acute and persistent arthralgia. The disease can cause severe morbidity and, since 2005, fatality. The virus is endemic to tropical regions, but the spread of Aedes albopictus into Europe and the Americas coupled with high viraemia in infected travellers returning from endemic areas increases the risk that this virus could establish itself in new endemic regions. This Seminar focuses on the re-emergence of this disease, the clinical manifestations, pathogenesis of virus-induced arthralgia, diagnostic techniques, and various treatment modalities.

Poly-γ-glutamic acid nanoparticles and aluminum adjuvant used as an adjuvant with a single dose of Japanese encephalitis virus-like particles provide effective protection from Japanese encephalitis virus

To maintain immunity against Japanese encephalitis virus (JEV), a formalin-inactivated Japanese encephalitis (JE) vaccine should be administered several times. The repeated vaccination is not helpful in the case of a sudden outbreak of JEV or when urgent travel to a high-JEV-risk region is required; however, there are few single-injection JE vaccine options. In the present study, we investigated the efficacy of a single dose of a new effective JE virus-like particle preparation containing the JE envelope protein (JE-VLP). Although single administration with JE-VLP protected less than 50% of mice against lethal JEV infection, adding poly(γ-glutamic acid) nanoparticles (γ-PGA-NPs) or aluminum adjuvant (alum) to JE-VLP significantly protected more than 90% of the mice. A single injection of JE-VLP with either γ-PGA-NPs or alum induced a significantly greater anti-JEV neutralizing antibody titer than JE-VLP alone. The enhanced titers were maintained for more than 6 months, resulting in long-lasting protection of 90% of the immunized mice. Although the vaccine design needs further modification to reach 100% protection, a single dose of JE-VLP with γ-PGA-NPs may be a useful step in developing a next-generation vaccine to stop a JE outbreak or to immunize travelers or military personnel.

Clinical Profile of Chikungunya Patients during the Epidemic of 2007 in Kerala, India

Background:

The association of the present Chikungunya pandemic with a mutation in the Chik virus is already established in many parts of the world, including Kerala. Kerala was one of the worst-affected states of India in the Chikungunya epidemic of 2006–2007. It is important to discuss the clinical features of patients affected by Chikungunya fever in the context of this change in the epidemiology of the disease.

Aim:

This study tries to analyze the clinical picture of the Chikungunya patients in Kerala during the epidemic of 2007.

Setting and Design:

A cross-sectional survey was carried out in five of the most affected districts in Kerala, India.

Materials and Methods:

A two-stage cluster sampling technique was used to collect the information. Ten clusters each were selected from all the five districts, and the size of the clusters were 18 houses each. A structured interview schedule was used for data collection. Diagnosis based on clinical signs and symptoms was the major case-finding strategy.

Results and Conclusion:

Of the 3623 residents in the surveyed households, 1913 (52.8%) had Chikungunya clinically. Most of the affected were in the adult age group (73.4%). Swelling of the joints was seen in 69.9% of the patients, followed by headache (64.1%) and itching (50.3%). The knee joint was the most common joint affected (52%). The number of patients with persistence of any of the symptoms even after 1 month of illness was 1388 (72.6%). Taking bed rest till the relief of joint pain was found to be a protective factor for the persistence of the symptoms. Recurrence of symptoms with a period of disease-free interval was complained by 669 (35.0%) people. Older age (>40 years), a presentation of high-grade fever with shivering, involvement of the small joints of the hand, presence of rashes or joint swelling during the first week of fever and fever lasting for more than 1 week were the significant risk factors for recurrence of symptoms predicted by a binary logistic regression model. In conclusion, we found that there is substantial acute and chronic morbidity associated with the Chikungunya epidemic of 2007.

Cell-based analysis of Chikungunya virus membrane fusion using baculovirus-expression vectors

Chikungunya virus infection has emerged in many countries over the past decade. There are no effective drugs for controlling the disease. To develop cell-based system for screening anti-virus drugs, a bi-cistronic baculovirus expression system was utilized to co-express viral structural proteins C (capsid), E2 and E1 and the enhanced green fluorescence protein (EGFP) in Spodoptera frugiperda insect cells (Sf21). The EGFP-positive Sf21 cells fused with each other and with uninfected cells to form a syncytium, allowing characterization of cholesterol and low pH requirements for syncytium formation. Western blot analysis showed three structural proteins were expressed in baculovirus infected cells. The structural proteins of Chikungunya virus that is required for cell fusion was determined with various recombinant baculoviruses bearing different lengths of the viral structural protein genes. Protein E1 was required for cell fusion and indicating that Chikungunya viral membrane fusion was a class II membrane fusion. It was also demonstrated that the heterologous expression of alphavirus monomeric E1 can induce insect cell fusions. Furthermore, this cell-based system provides a model for studying class II viral membrane fusion.

Experimental infection of Japanese encephalitis virus in dogs

A previous serosurvey of Japanese encephalitis virus (JEV) among dogs suggested that dogs are well suited for use as sentinels for assessing the risk of JEV transmission to humans. To examine the clinical symptoms and duration of anti-JEV antibodies in dogs, three dogs were experimentally challenged with JEV. All JEV-infected dogs did not show any clinical signs or abnormal blood tests, except for C-reactive protein. Virus-neutralization titers rapidly increased and were maintained until 70 days postinfection, and neither the virus nor the viral genome was detected in blood. Thus, since dogs live in close proximity to humans as companion animals, they are well suited for use as sentinels for surveying the human risk of JEV infection.