การประช มส มมนาเช งปฏ บ ต การ การเตร ยมความพร อมร บม อโรคต ดเช ออ บ ต ใหม อ บ ต ซ า และการรายงานโรคระบาดส ตว

Transcription

1 การประช มส มมนาเช งปฏ บ ต การ การเตร ยมความพร อมร บม อโรคต ดเช ออ บ ต ใหม อ บ ต ซ า และการรายงานโรคระบาดส ตว สพ.ญ.ดร.วราพร พ มพ ประไพ ภาคว ชาส ตวแพทยสาธารณส ขศาสตร คณะส ตวแพทยศาสตร มหาว ทยาล ยเกษตรศาสตร

2 Emerging & Re-emerging Disease Global trends

3 The U.S. Government & Global Emerging Infectious Disease Preparedness and Response Emerging infectious disease (EID): An infectious disease that is newly recognized as occurring in humans; one that has been recognized before but is newly appearing in a different population or geographic area than previously affected; one that is newly affecting many more individuals; and/or one that has developed new attributes (e.g., resistance or virulence). Source: access 14 April 2014

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5 Examples of emerging and re-emerging diseases throughout the world.

6 Maps are derived for EID events caused by a, zoonotic pathogens from wildlife, b, zoonotic pathogens from non-wildlife, c, drug-resistant pathogens and d, vector-borne pathogens. The relative risk is calculated from regression coefficients and variable values in Table 1 (omitting the variable measuring reporting effort), categorized by standard deviations from the mean and mapped on a linear scale from green (lower values) to red (higher values). Nature 451, (21 February 2008) doi: /nature06536

7 Lancet. Dec 1, 2012; 380(9857): doi: /S (12)

8 Lancet. Dec 1, 2012; 380(9857): doi: /S (12)

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10 Porcine Reproductive and Respiratory Syndrome (PRRS) African Swine Fever (ASF) Avian influenza (AI) West Nile Encephalitis (WNE) Nipah Encephalitis Bovine Spongiform Encephalopathy (BSE)

11 Emerging vector-borne diseases Vector-borne diseases rely upon organisms, named vectors, such as mosquitoes, ticks or sandflies that have an active role in the transmission of a pathogen from one host to the other. Many factors that may facilitate the introduction and establishment of disease vectors, reservoirs or pathogens in new geographic areas could lead to the emergence of a disease. These factors include international travel and trade, e.g. legal and illegal trade in animals and animal products, new agricultural practices and land-use patterns, sociodemographic evolution and climatic changes. (Source: access 16 April 2014)

12 Arbovirus Arbovirus: A class of viruses transmitted to humans by arthropods such as mosquitoes and ticks. The first two letters of the words arthropod' and borne, make up the 'arbo' that now designates this group of viruses as arthropodborne. The name arbovirus was coined in part by Dr. William C. Reeves ( ) to connote the class of viruses carried by insects and responsible for diseases like malaria, dengue fever, encephalitis and West Nile. (Source: access 14 Jan 09)

13 Arthopod-borne viruses (Arboviruses) is maintained in nature between the vector and an animal host. Man gets infected incidentally but is a dead end of infection. Viruses maintained in nature principally, or to an important extent, through biological transmission between susceptible vertebrate hosts by hematophagus arthropods or through transovarian and possibly venereal transmission in arthropods. (WHO)

14 In general arboviruses belong to three families:- 1. Togaviruses - genera alphaviruses e.g. EEE, WEE, VEE 2. Bunyaviruses - e.g. Sicilian Sandfly Fever, Rift Valley Fever, Crimean-Congo Haemorrhagic Fever 3. Flaviviruses - e.g. St Louis Encephalitis, Japaneses Encephalitis, Yellow Fever, Dengue, West Nile Encephalitis

15 Arboviral zoonoses Mosquito Togavirus; Arboviral encephalitis (EEE, WEE, VEE, Chikungunya, O nyong nyong virus, Ross river virus) Bunyavirus; Arboviral encephalitis (La Crosse encephalitis, California encephalitis), Viral hemorrhagic fever (Rift valley fever) Flavivirus; AE (JE, West Nile virus, Murray valley encephalitis, St. Louis encephalitis) VHF (Dengue fever), Yellow fever Tick Bunyavirus; VHF (Crimean-Congo hemorrhagic fever) Flavivirus; AE (Tick-borne encephalitis, Powassan), VHF (Omsk hemorrhagic fever, kyasanur forest disease/alkurma) Reovirus; Colorado tick fever (Source: access 14 Jan 09)

16 Arboviral encephalitis Inflammation of the brain (encephalitis) caused by infection with an arbovirus, a virus transmitted by a mosquito, tick or another arthropod. Infection of vertebrates, including humans, occurs when an infected arthropod feasts upon them for a blood meal.

17 West Nile Virus (WNV) Found in both tropical and temperate regions. It mainly infects birds, but also humans, horses, dogs, cats, bats, chipmunks, skunks, squirrels, and domestic rabbits. WNV has three different effects on humans. The first is an asymptomatic infection; the second is a mild febrile syndrome termed West Nile Fever, the third is a neuroinvasive disease termed West Nile meningitis or encephalitis.

18 The birds are amplifying hosts, developing sufficient viral levels to transmit the infection to other birds and also humans. In mammals the virus does not multiply as readily and mosquitoes biting infected mammals do not ingest sufficient virus to become infected, making mammals so-called dead-end infections.

19 Transmission West Nile virus is most commonly transmitted to humans by mosquitoes. Additional routes of human infection have also been documented. It is important to note that these methods of transmission represent a very small proportion of cases: Blood transfusion Organ transplants Exposure in a laboratory setting From mother to baby during pregnancy, delivery, or breastfeeding

20 West Nile virus is not transmitted: From person-to-person or from animal-to-person through casual contact. Normal veterinary infection control precautions should be followed when caring for a horse suspected to have this or any viral infection. From handling live or dead infected birds. You should avoid bare-handed contact when handling any dead animal. If you are disposing of a dead bird, use gloves or double plastic bags to place the carcass in a garbage can. Through consuming infected birds or animals. In keeping with overall public health practice, and due to the risk of known food-borne pathogens, always follow procedures for fully cooking meat from either birds or mammals.

21 In the US in the year 2013, A total of 2,374 cases of WNV diseases, including 1,205 neuroinvasive disease (WNND) cases and 114 deaths were reported. There is no vaccine for humans. A vaccine for horses based on killed viruses exists; some zoos have given this vaccine to their birds, although its effectiveness there is unknown. Dogs and cats show few if any signs of infection.

22 Studies of phylogenetic lineages have determined that WNV emerged as a distinct virus around 1000 years ago. This initial virus developed into two distinct lineages, Lineage 1 and its multiple profiles is the source of the epidemic transmission in Africa and throughout the world, while Lineage 2 remains as an Africa zoonose. Culex species and susceptible birds the particular species dependent on geographic location. In all, 59 species of mosquitoes and 284 species of birds have been found infected in North America.

23 Worldwide distribution of West Nile virus Viruses 2013, 5(12), ; doi: /v

24 American crow Blue Jay Culex pipiens House sparrow Culex quinquefasciatus Flamingo American Robin

25 Global distribution of Cx. pipiens complex mosquitoes Viruses 2013, 5(12), ; doi: /v

26 Spread of WNV throughout the Americas. Published by AAAS A M Kilpatrick Science 2011;334:

27 West Nile Virus Map:Cumulative Human Cases 2013 Data as of 3 am, Jan 07, 2014 Human: 2,374 Birds: 1,591 Mosquitoes: 13,336 Vets: 373 (Source: access 16 April 2014)

28 West Nile Virus Neuroinvasive Disease Incidence by State United States, 2013 (as of January 7, 2014) access 16 April 2014)

29 Cumulative number of West Nile fever cases, by affected area, as of 6/11/2013 (N = 783 cases)

30 Anthropogenic processes that facilitate the introduction and establishment of novel pathogens and increase their transmission. A M Kilpatrick Science 2011;334: Published by AAAS

31 Emerging bat-borne diseases Bat are natural reservoirs of emerging and reemerging human virus including: Rabies virus; 7 genotypes of Lyssavirus Henipavirus; Hendra virus and Nipah virus SARS-CoV Filovirus; Marburg virus and Ebola virus Melaka vius Protien Cell 2010, 1(2): , DOI /s

32 Nipah virus Nipah virus was identified in 1998 when it caused an outbreak of neurological and respiratory disease on pig farms in peninsular Malaysia, resulting in 105 human deaths and the culling of one million pigs. In Singapore, 11 cases including one death occurred in abattoir workers exposed to pigs imported from the affected Malaysian farms. The Nipah virus has been classified by the CDC as a Category C agent.

33 Symptoms of infection from the Malaysian outbreak were primarily encephalitic in humans and respiratory in pigs. Later outbreaks have caused respiratory illness in humans, increasing the likelihood of human-to-human transmission and indicating the existence of more dangerous strains of the virus.

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35 Based on seroprevalence data and virus isolations, the primary reservoir for Nipah virus was identified as Pteropid fruit bats including Pteropus vampyrus (Malayan flying fox) and Pteropus hypomelanus (Island flying fox), both of which occur in Malaysia.

36 The transmission of Nipah virus from flying foxes to pigs is thought to be due to an increasing overlap between bat habitats and piggeries in peninsular Malaysia. At the index farm, fruit orchards were in close proximity to the piggery, allowing the spillage of urine, feces and partially eaten fruit onto the pigs. Retrospective studies demonstrate that viral spillover into pigs may have been occurring in Malaysia since 1996 without detection. During 1998, viral spread was aided by the transfer of infected pigs to other farms where new outbreaks occurred.

37 Other Nipah virus outbreaks In Bangladesh in 2004, humans became infected with NiV as a result of consuming date palm sap that had been contaminated by infected fruit bats. Human-to-human transmission has also been documented, including in a hospital setting in India. The outbreak sites lie within the range of Pteropus species (Pteropus giganteus). As with Hendra virus, the timing of the outbreaks indicates a seasonal effect.

38 Nipah virus surveillance Nipah virus has been isolated from Lyle's flying fox (Pteropus lylei) in Cambodia and viral RNA found in urine and saliva from P. lylei and Horsfield's roundleaf bat (Hipposideros larvatus) in Thailand. Infective virus has also been isolated from environmental samples of bat urine and partially-eaten fruit in Malaysia.

39 Nipah virus surveillance Antibodies to henipaviruses have also been found in fruit bats in Madagascar (Pteropus rufus, Eidolon dupreanum) and Ghana (Eidolon helvum) indicating a wide geographic distribution of the viruses. No infection of humans or other species have been observed in Cambodia, Thailand or Africa.

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42 Surveillance hospitals and locations of outbreak clusters and sporadic cases of Nipah virus infection, Bangladesh, (Source: access 16 April 2014)

43 Nipah virus infection: Symptom& Treatment NiV infection in humans has a range of clinical presentations, from asymptomatic infection to acute respiratory syndrome and fatal encephalitis. NiV is also capable of causing disease in pigs and other domestic animals. There is no vaccine for either humans or animals. The primary treatment for human cases is intensive supportive care.

44 Pathology of Nipah virus In humans, the infection presents as fever, headache and drowsiness. Cough, abdominal pain, nausea, vomiting, weakness, problems with swallowing and blurred vision are relatively common. About a quarter of the patients have seizures and about 60% become comatose and might need mechanical ventilation.

45 Pathology of Nipah virus In patients with severe disease, their conscious state may deteriorate and they may develop severe hypertension, fast heart rate, and very high temperature. Nipah virus is also known to cause relapse encephalitis. In animals, especially in pigs, the virus causes porcine respiratory and neurologic syndrome also known as barking pig syndrome or one mile cough.

46 Course of emergence The emergence of henipaviruses parallels the emergence of other zoonotic viruses in recent decades. SARS coronavirus, Australian bat lyssavirus, Menangle virus and probably Ebola virus and Marburg virus are also harbored by bats and are capable of infecting a variety of other species. The emergence of each of these viruses has been linked to an increase in contact between bats and humans, sometimes involving an intermediate domestic animal host.

47 The increased contact is driven both by human encroachment into the bats territory and by movement of bats towards human populations due to changes in food distribution and loss of habitat. There is evidence of habitat loss for flying foxes both in South Asia and as well as encroachment of human dwellings and agriculture into the remaining habitats, creating greater overlap of human and flying fox distributions.