Molecular characterization of Japanese encephalitis virus strains prevalent in Chinese swine herds

Japanese encephalitis virus (JEV) is the leading cause of viral encephalitis in Asia and domestic pigs serve as the amplifying hosts. In the present study, the full genomic sequences of two JEV strains (HEN0701 and SH0601) isolated from pigs in China were determined and compared with other 12 JEV strains deposited in GenBank. These two strains had an 88.8% nucleotide sequence similarity and 97.9% deduced amino acid sequence homology. HEN0701 had high nucleotide sequence and high amino acid sequence identity with genotype I (GI) strains, while SH0601 had high nucleotide sequence and high amino acid sequence identity with GIII strains at both the gene and full genome levels. Further phylogenetic analysis showed that HEN0701 belonged to the JEV GI group and SH0601 was classified as a GIII strain. Analysis of codon usage showed there were a few differences between the GI and GIII strains in nucleotide composition and codon usage for the open reading frames.

Molecular characterization of Japanese encephalitis virus strains prevalent in Chinese swine herds

Japanese encephalitis virus (JEV) is the leading cause of viral encephalitis in Asia and domestic pigs serve as the amplifying hosts. In the present study, the full genomic sequences of two JEV strains (HEN0701 and SH0601) isolated from pigs in China were determined and compared with other 12 JEV strains deposited in GenBank. These two strains had an 88.8% nucleotide sequence similarity and 97.9% deduced amino acid sequence homology. HEN0701 had high nucleotide sequence and high amino acid sequence identity with genotype I (GI) strains, while SH0601 had high nucleotide sequence and high amino acid sequence identity with GIII strains at both the gene and full genome levels. Further phylogenetic analysis showed that HEN0701 belonged to the JEV GI group and SH0601 was classified as a GIII strain. Analysis of codon usage showed there were a few differences between the GI and GIII strains in nucleotide composition and codon usage for the open reading frames.

Japanese encephalitis: a review of the Indian perspective

Japanese encephalitis virus (JEV) causes Japanese encephalitis, which is a leading form of viral encephalitis in Asia, with around 50,000 cases and 10,000 deaths per year in children below 15 years of age. The JEV has shown a tendency to extend to other geographic regions. Case fatality averages 30% and a high percentage of the survivors are left with permanent neuropsychiatric sequelae. Currently, there is no cure for JEV, and treatment is mainly supportive. Patients are not infectious, but should avoid further mosquito bites. A number of antiviral agents have been investigated; however, none of these have convincingly been shown to improve the outcome of JEV. In this review, the current knowledge of the epidemiology and the pathogenesis of this deadly disease have been summarized.

Changing landscape of acute encephalitis syndrome in India: A systematic review.

Background. Seasonal outbreaks of acute encephalitis syndrome (AES) occur with striking regularity in India and lead to substantial mortality. Several viruses, endemic in many parts of India, account for AES. Although Japanese encephalitis virus (JEV) is a key aetiological agent for AES in India, and has attracted countrywide attention, many recent studies suggest that enteroviruses and rhabdoviruses might account for outbreaks of AES. We did a systematic review of published studies to understand the changing landscape of AES in India. Methods. Data sources: Electronic databases (PubMed, Web of Science and BIOSIS) from the start of the database to 2010. We also hand-searched journals and screened reference lists of original articles, reviews and book chapters to identify additional studies. Study selection: We included studies only on humans and from three time-periods: pre-1975, 1975–1999 and 2000– 2010. Data extraction: Independent, duplicate data extraction and quality assessment were conducted. Data extracted included study characteristics, type of study and aetiological agent identified. Data synthesis: Of the 749 unique published articles screened, 57 studies met the inclusion criteria (35 outbreak investigations and 22 surveillance studies). Results. While most studies from 1975 to 1999 identified JEV as the main cause of AES, many studies published after 2000 identified Chandipura and enteroviruses as the most common agents, in both outbreaks and surveillance studies. Overall, a positive yield with respect to identification of aetiological agents was higher in outbreak investigations as compared to surveillance studies. Conclusion. The landscape of AES in India has changed in the previous decade, and both outbreak investigations and surveillance studies have increasingly reported non-JEV aetiologies. Because of these findings, there is a need to explore additional strategies to prevent AES beyond vector control and JEV vaccination.

Isolation and genetic characterization of Japanese encephalitis virus from equines in India

Japanese encephalitis (JE) is an important vector-borne viral disease of humans and horses in Asia. JE outbreaks occur regularly amongst humans in certain parts of India and sporadic cases occur among horses. In this study, JE seroprevalence and evidence of JE virus (JEV) infection among horses in Haryana (India) is described. Antibodies against JEV were detected in 67 out of 637 (10.5%) horses screened between 2006 and 2010. Two foals exhibiting neurological signs were positive for JEV RNA by RT-PCR; JEV was isolated from the serum of one of the foals collected on the second day of illness. This is the first report of JEV isolation from a horse in India. Furthermore, a pool of mosquitoes collected from the premises housing these foals was positive for JEV RNA by RT-PCR. Three structural genes, capsid (C), premembrane (prM), and envelope (E) of the isolated virus (JE/eq/India/H225/2009) spanning 2,500 nucleotides (from 134 to 2,633) were cloned and sequenced. BLAST results showed that these genes had a greater than 97% nucleotide sequence identity with different human JEV isolates from India. Phylogenetic analysis based on E- and C/prM genes indicated that the equine JEV isolate belonged to genotype III and was closely related to the Vellore group of JEV isolates from India.

Clinical and etiological profile of acute febrile encephalopathy in eastern Nepal.

Objective. To investigate the clinical and etiological profile of acute febrile encephalopathy in children presenting to a tertiary care referral center of Eastern Nepal. Methods. 107 children (aged 1 month to 14 yr) presenting to the emergency with fever (> 380 C) of less than 2 wk duration with altered sensorium with/ or without seizure were prospectively investigated for etiological cause. The investigations included blood and CSF counts, blood and CSF cultures, peripheral smear and serology for malarial parasite, and serology for Japanese encephalitis (JE) virus. Other investigations included EEG and CT or MRI wherever indicated. Results. The most common presenting complaints apart from fever and altered sensorium were headache and vomiting. Convulsions, neck rigidity, hypertonia, brisk deep tendon reflexes, extensor plantar response and focal neurological deficits were seen in 50%, 57%, 22.4%, 28%, 39.3% and 9.3% of the subjects, respectively. The diagnoses based on clinical presentation and laboratory findings were pyogenic meningitis in 45 (42%), non JE viral encephalitis in 26 (25%), JE in 19 (18%), cerebral malaria in 8 (7%), herpes encephalitis and tubercular meningitis in 4 (4%) each, and typhoid encephalopathy in 1 case. Conclusion. Pyogenic meningitis and viral encephalitis including JE are the most common causes of acute presentation with fever and encephalopathy. Preventive strategies must be directed keeping these causes in mind.

Preventive strategies for frequent outbreaks of Japanese encephalitis in Northern India.

Japanese encephalitis (JE) remains the most important cause of acute viral encephalitis and continues to spread to hitherto unaffected regions like Indonesia, Pakistan and Australia. Approximately 60% of the world population inhabits JE endemic areas. Despite its restricted range mostly in the developing countries,a high annual incidence of 50,000 cases and about 10,000 deaths has been reported. Disease can be fatal in 25% ases. Magnitude of the problem is even more alarming since the survivors are left with serious long-term neuropsychiatric sequelae. Almost every two years,epidemics of JE occur in Indian subcontinent with a high mortality. JE virus infection results in different disease manifestations in host from mild subclinical febrile illness to clinical infections leading to encephalitis. No antiviral treatment is so far available for JE. The prevention of JE can be achieved by controlling the vector or by immunization regime. The vector control in the rural areas,which are the worst affected ones,is practically almost impossible. Three vaccines that have been implicated against JE include inactivated mouse brain derived, inactivated cell culture derived and cell culture derived live attenuated JE vaccine. But each has its own limitation. Currently,attempts to synthesize recombinant DNA vaccine are being made. New therapeutics are on the way of development like use of minocycline, short interfering RNA, arctigenin, rosmarinic acid, DNAzymes etc. However,the immune mechanisms that lead to JE are complex and need to be elucidated further for the development of therapeutics as well as safe and efficacious JE vaccines.

Chikungunya fever, falciparum malaria, dengue fever, Japanese encephalitis... are we listening to the warning signs for public health in India?

The 2005-epidemic of Chikungunya fever highlights the weaknesses of public health in India. The failure to control mosquitoes, and the illnesses transmitted by them, has resulted in recurrent outbreaks all over the country. This is inevitable given the larger scenario: neglect of the basic requirements of health; poor political support for health; a weak public health capacity; centralised programmes for control based on selective interventions, and poorly-planned development projects which have created conditions ideal for the outbreak of disease. All these issues are concerns for public health ethics and must be addressed to tackle the problems posed by mosquito-borne as well as other communicable diseases.

The seroprevalence of Japanese encephalitis virus in goats raised in Korea

Japanese encephalitis virus (JEV) causes a mosquitoborne viral zoonosis that is becoming increasingly important to public health in east and south Asia. Although JEV is primarily associated with reproductive failure in swine, JEV infection can cause fever and headache in humans and is associated with aseptic meningitis and encephalitis. The exact mode of transmission, including host range and possible source of viral amplification within livestock, is still not completely clear. This study consisted of a serological survey of JEV infection in goats. A total of 804 goat serum samples were collected from 144 farms in Korea between May 2005 and May 2006. The incidence of positive cases was 12.1% (97 out of 804 goats). The seroprevalence of JEV infection in the 144 farms screened was 31.3% (45/144), indicating that JEV infection is frequent in goat farms in Korea. In addition, three districts of Korea (mainly in the southern region) had a higher seroprevalence of JEV compared to other areas. The results suggest that goats could be monitored epidemiologically as a sentinel animal for JEV transmission in Korea.

Epidemiological situation of Japanese encephalitis in Nepal.

A human Japanese encephalitis (JE) case is considered to have elevated temperature (over 380 C) along with altered consciousness or unconsciousness and is generally confirmed serologically by finding of specific anti-JE IgM in the cerebro spinal fluid. No specific treatment for JE is available. Only supportive treatment like meticulous nursing care, introduction of Ryle's tube if the patient is unconscious, dextrose solution if dehydration is present, manitol injection in case of raised cranial temperature and diazepam in case of convulsion. Intra venous fluids, indwelling catheter in conscious patient and corticosteroids unless indicated should be avoided. Pigs, wading birds and ducks have been incriminated as important vertebrate amplifying hosts for JE virus due to viremia in them. Man along with bovines, ovines and caprines is involved in transmission cycle as accidental hosts and plays no role in perpetuating the virus due to the lack of viremia in them. The species Cx tritaeniorhyncus is suspected to be the principal vector of JE in Nepal as the species is abundantly found in the rice-field ecosystem of the endemic areas during the transmission season and JE virus isolates have been obtained from a pool of Cx tritaeniorhyncus females. Mosquito vector become infective 14 days after acquiring the JR virus from the viremic host. The disease was first recorded in Nepal in 1978 as an epidemic in Rupandehi district of the Western Development Region (WDR) and Morang of the Eastern Region (EDR). At present the disease is endemic in 24 districts. Although JE as found endemic mainly in tropical climate areas, existence and proliferation of encephalitis causing viruses in temperate and cold climates of hills and valleys are possible. Total of 26,667 cases and 5,381 deaths have been reported with average case fatality rate of 20.2% in an aggregate since 1978. More than 50% of morbidity and 60% mortality occur in the age group below 15 years. Upsurge of cases take place after the rainy season (monsoon). Cases start to appear in the month of April - May and reach its peak during late August to early September and start to decline from October. There are four designated referral laboratories, namely National Public Health Laboratory (Teku), Vector Borne Diseases Research and Training Center (Hetauda), B.P. Koirala Institute of Medical Sciences (Dharan) and JE Laboratory (Nepalgunj), for confirmatory diagnosis of JE. For prevention of JE infection; chemical and biological control of vectors including environmental management at breeding sites are necessary. Segregate pigs from humans habitation. Wear long sleeved clothes and trousers and use repellent and bed net to avoid exposure to mosquitos. For the prevention of the disease in humans, safe and efficacious vaccines are available. Therefore immunize population at risk against JE. Immunize pigs at the surroundings against JE. 225,000 doses of live attenuated SA-14-14.2 JE vaccine were received in donation from Boran Pharmaceuticals, South Korea for the first time in Nepal. Altogether 224,000 children aged between 1 to 15 years were vaccinated in Banke, Bardiya and Kailali districts during 1999. From China also, 2,000,000 doses of inactivated vaccine were received in 2000 and a total of 481,421 children aged between 6m to 10 yrs were protected from JE during 2001/2002. Ministry of Agriculture, Department of Livestock Services has vaccinated around 200,000 pigs against JE in terai zone during February 2001.

Illustrated keys to the mosquitoes of Thailand. II. Genera Culex and Lutzia.

Illustrated keys for the identification of the fourth-instar larvae and adult females of the mosquito genera Culex and Lutzia is presented, along with information on the geographic distribution of each species, and bionomics. Eighty-two species belonging to subgenera Culex, Culiciomyia, Eumelanomyia, Lophoceraomyia, and Oculeomyia of genus Culex, and three species belonging to subgenus Metalutzia of genus Lutzia are recognized in Thailand. Subgenus Oculeomyia includes a probable new species near Cx. infula and Lt. vorax is recognized as a new country record.

First time detection of Japanese encephalitis virus antigen in dry and unpreserved mosquito Culex tritaeniorhynchus Giles, 1901, from Karnal district of Haryana state of India.

Japanese encephalitis virus (JEV) antigen has been detected by antigen capture enzyme linked immunosorbentassay (ELISA) in dry specimens of the mosquito Culex tritaeniorhynchus Giles, 1901, collected from Karnal district of Haryana state in northern India. These mosquitoes were stored in dry condition for 20 months, at room temperature, before processing. The procedure of detecting JEV infection in long time stored, dry vector mosquitoes, has important application in the surveillance of Japanese encephalitis.

Japanese encephalitis in Assam, northeast India.

Japanese encephalitis is one of the major public health problems in Assam, northeast India. We aimed to elucidated the clinical and epidemiological profile of the disease during several outbreaks in Assam in 3 consecutive years. Cerebro-spinal fluid and or serum samples of 348 out of 773 clinically-suspected viral encephalitis patients admitted to different hospitals during the period June to August of 2000 to 2002 were tested for detection of JE specific IgM antibody, employing MAC ELISA test at RMRC (ICMR), Dibrugarh. Diagnosis was confirmed in 53.7% patients with the ratios of 1.8:1 and 1.4:1 for male to female and pediatric to adult patients respectively. Most of the cases were pediatrics at the age of 7 to 12 years (34.2%). Fever (100%), altered sensorium (81.8%), headache (70.6%), neck rigidity (54.0%), abnormal movement (51.3%), exaggerated reflexes (48.1%), restlessness (44.9%), increased muscle tone (35.3%), convulsion (33.7%) and coma (20.9%) were the major clinical findings. The majority of cases (96.3%) were from rural areas. House surroundings close to water bodies, rice cultivation, association with pigs, and climatic conditions were environmental factors affecting the abundance of the potential mosquito vectors of the disease.

Control of Japanese encephalitis in India: a reality.

Japanese encephalitis is considered as a serious disease due to the complexity of the disease and lack of specific treatment. A secular trend towards declining of JE has been brought in China, Korea, and Japan with widespread use of JE vaccine. In India, the actual JE burden could be estimated only by strengthening diagnostic facilities for JE confirmation in hospitals. However, the available records at present indicate a rising trend in JE- occurrence and expansion of the disease into JE non-endemic areas, which cannot be ignored. JE control through vector control methods has limitations owing to sustainability and cost effectiveness of the programs. Under these circumstances, feasibility of JE vaccination in India has to be considered as a preventive measure, for which identification of risk areas, target populations to be immunized, cost-evaluation of immunization is emphasized. Since, JE vaccine is produced in India, extension of the availability of this vaccine into routine JE-immunization programs is not remote. China has proved that countries with limited sources can produce safe and effective JE vaccines.