Several transboundary aquatic animal diseases have swept the region over the past 25 years causing massive economic and social losses. These include spread and outbreaks of epizootic ulcerative syndrome EUS in freshwater fish, viral nervous necrosis VNN in marine fish, viral haemorrhagic septicaemia VHS in marine and freshwater fish, and several viral diseases in shrimps e. The spread of these transboundary diseases clearly demonstrates the vulnerability of the aquaculture industry to disease emergence where impacts have been aggravated by the lack of effective preparedness and response when diseases emerge.
There have been reports of its spread in South American countries but limited report is available in this regard. This disease caused significant losses in the production of Penaeus monodon and P. NACA s regional response to this disease during its initial outbreak in Viet Nam, Thailand and Malaysia signified that improved control on transboundary diseases and emergency preparedness are still needed in the region. In collaboration with international organizations OIE, FAO , NACA has implemented awareness programs, efficient information dissemination, and emergency regional expert consultation to address this disease problem.
All of these efforts, together with subsequent studies on prevention and disease management, have paved the way in preventing further spread of this disease to other shrimp-producing countries so far. However, the risk is still very high that this disease will spread, as transboundary movement of live shrimps within and outside the region is inevitable.
In addition, other emerging diseases are now affecting production of major cultured shrimps in the region.
Emerging and Re-emerging Arboviral Diseases as a Global Health Problem
By and large, outbreaks of damaging aquatic animal diseases are likely to continue and the potential consequences are likely to increase with the expansion intensification of aquaculture systems and introduction of new species for culture. Various encephalitis outbreaks have recently emerged in Asia such as the fatal outbreak of enterovirus 71 EV71 that occurred in mid in Cambodia affecting very young children most below 3 years, all below 12 years. This hypothesis is also strengthened by the recent apparent increase in emerging infectious diseases , many of which have been linked to human activities that impact the environment and to the spreading of pathogens to new geographic regions Granerod et al.
From this perspective, the Southeast Asian region, a particularly significant biodiversity hotspot, is at high risk for new pathogen emergence. Indeed, growing human populations, increasing urbanization and frequent contact with wildlife and domesticated animals have created novel opportunities for the emergence of pathogens such as SARS at the end of , and highly facilitated the spread of infectious diseases such as H5N1 high - pathogenicity avian influenza virus since , and H1N1 pandemic influenza virus in The population in developing Southeast Asian countries is particularly at risk for the circulation of emerging or reemerging infectious agents and for this reason the surveillance and investigation of acute encephalitis syndrome in this region is of utmost public health importance, both locally and globally.
Surveillance and diagnostic capabilities for encephalitis remain poor and still suffer from serious shortcomings in most Southeast Asian countries and beyond. Although the burden of non-infectious encephalitis in this region remains to be ascertained, the best laboratories only identify etiological infective agents in less than half of patients. Moreover, because of the absence of reliable microbiological diagnostic capacity in the majority of public referral hospitals, local clinicians have to treat acute encephalitis syndromes mostly empirically, with little evaluation of the effectiveness of their clinical approach.
Even if some of the most common causes of acute encephalitis syndrome may be vaccine-preventable, systematic data regarding the contribution of these diseases are lacking and no reliable data are available to define the burden of these infections, to describe the full clinical spectrum and characteristics of acute central nervous system infections, and to develop diagnostic and therapeutic algorithms to improve patient care. Besides, whatever the nature and magnitude of the encephalitis burden in Southeast Asia and the criteria used to assess it i.
WP1 , focused on clinical and epidemiological studies , will be responsible for the rigorous identification and inclusion of infectious encephalitis cases, the collection and storage of clinical data and biological samples to inform microbiological diagnosis. Training of medical personnel in clinical sites participating to the study will be an important aspect of the WP1 mission.
Identification of clusters of cases unusual by their numbers, the causative pathogen, or the clinical presentation, will trigger field investigations conducted in collaboration with the WP3 teams. Japanese encephalitis JE virus is another flavivirus that is considered rare in Australia. However, in , JE was documented in the Torres Strait Islands, with three cases, two of which were fatal. Subsequently, in , a human case was recognised in mainland Australia, in a fisherman from the Mitchell River on Cape York.
Emerging infectious diseases of food crops in Asia
The global importance of JE is significant, with about 50 cases and 15 deaths a year worldwide. It is transmitted between animals by Culex mosquitoes, with an enzootic cycle involving wild and domestic birds and animals, particularly pigs. Humans are infected as accidental hosts, and, as human viraemia is usually brief and of low concentration, rarely transmit the virus.
The ratio of symptomatic to asymptomatic infection is estimated to be between 1: 25 and 1: JE has a short prodrome which may include coryza, diarrhoea, and rigors. Seizures are common, particularly in children, and extrapyramidal features, such as tremor, hypertonia, cogwheel rigidity, choreoathetosis, opsoclonus, myoclonus and lip smacking, are suggestive of JE. Diagnosis is usually serological, with enzyme immunoassay IgM and IgG capture assays useful for testing serum and cerebrospinal fluid case history, Box 6.
The vaccine is administered in a series of three doses, at 0, 7 and 30 days, with a booster recommended at one year. The combination of itching, urticaria, and occasionally angio-oedema of the face, which can be severe, has been recognised since , with an incidence estimated at 2—10 per vaccine doses, and higher in those with a history of urticaria.
Infection with these seven viruses may present similarly — an acute febrile illness and encephalitis are common. ABL may present similarly to rabies. The epidemiological pattern is an important clue to diagnosis, and questions about patients' residence, travel and contacts are vital.
The spectrum of disease and geographical distribution of viral infections in Australia continue to evolve, providing an ongoing challenge for clinicians and researchers. The increased ease of travel has reduced the remoteness of Australasia. Recent experience has shown that new infectious diseases can emerge from both within and outside Australia, and further new viral infections can be expected in the future.
Emerging viral diseases of Southeast Asia and the Western Pacific.
Rabies vaccine and immunoglobulin offer protection against infection with Australian bat lyssavirus and should be given after a bite or scratch from a bat in Australia 13 E4. Vaccine against Japanese encephalitis should be recommended for people who intend to live in an endemic area for over 30 days 13 E4. Avoid contact with bats; immunoprophylaxis Box 3. Residence in Australia particularly northern Australia , especially during wet season February to July.
Mosquito avoidance measures; JE vaccine if intend to travel to endemic areas for longer than 30 days. Wound cleansing with soap and water or antiseptic solution is vital; debridement if indicated. Immediate Day 0 administration of 1. Rabies immunoglobulin is not recommended. Presentation: A year-old woman was bitten and scratched on her arm by a bat that she accidentally disturbed while walking near her home outside Cairns. She presented to the emergency department of her local hospital. Management: Her wounds were cleaned and debrided. Rabies immunoglobulin was administered IU [4 mL] instilled into the wounds, and another IU [4 mL] intramuscularly.
She was also given the first dose of a course of human diploid cell rabies vaccine 1 mL of vaccine given intramuscularly the same night. The following day, she had headache and local pain. Further vaccine doses were given on Days 3, 7, 14 and Outcome: The patient's wounds healed with minimal scarring.
At follow-up after 18 months, she remained well. Rabies vaccine and immunoglobulin offer protection against Australian bat lyssavirus.
A bat scratch or bite in Australia is a strong indication for immediate wound cleaning and medical attention for possible debridement, along with rabies vaccine and immunoglobulin. The general public should avoid all contact with bats, especially bats that appear unwell. South-East Asia and Australia, showing areas where Japanese encephalitis is endemic and sporadic. Presentation: A year-old man presented with a three-day history of fever, rigors, headache and progressive confusion. He had recently returned on holiday from north Vietnam, where he had lived for several years.
Examination: He was disoriented, could not remember where he lived, had difficulty recognising his children and was incontinent of urine on several occasions. On examination, he had myoclonus of his upper limbs, with hypertonicity and hyperreflexia of all limbs, and extensor plantar responses. The rest of his physical examination gave normal results. Over the following 24 hours, he developed tonic—clonic seizures and choreoathetotic and lip-smacking movements. Investigations: Computed tomography and magnetic resonance imaging of the head showed no abnormalities.
Management and course: The patient was treated with intravenous fluids, anticonvulsants and empirical aciclovir.
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Over the following week, he had progressive neurological deterioration culminating in loss of consciousness and death. No autopsy was performed. The possibility of Japanese encephalitis was suggested by:. Publication of your online response is subject to the Medical Journal of Australia 's editorial discretion.
You will be notified by email within five working days should your response be accepted. Basic Search Advanced search search. Use the Advanced search for more specific terms. Title contains. Body contains. Date range from. Date range to. Article type. Author's surname. First page. Short reports. Guidelines and statements. Narrative reviews. Ethics and law. Medical education. Volume Issue 1. Med J Aust ; 1 : Topics Infectious diseases. Abstract Hendra virus infection should be suspected in someone with close association with horses or bats who presents acutely with pneumonia or encephalitis potentially after a prolonged incubation period.
Some of these are classed as "emerging", including: Hendra and Menagle viruses, which were identified for the first time in Australia, in and , respectively, 1 , 2 and have not been found elsewhere.