Presentation on theme: "30 July – 01 August, Chonburi, Thailand"— Presentation transcript:
130 July – 01 August, Chonburi, Thailand Global Situation for Plague, Anthrax, West Nile Virus, Leptospirosis and DengueWorkshop on Laboratory Diagnosis for Zoonotic Pathogens30 July – 01 August, Chonburi, ThailandDr Richard Brown, WHO Thailand
2Plague Causative Agent When infections occur Distribution Reservoir Yersinia PestisWhen infections occurThrough the bite of an infected rat fleaDistributionAmericas, Central / southern Africa, Central Asia, China, India, Mongolia (Myanmar, Laos PDR)ReservoirWild rodents (rats) are important as hosts for the flea vectorsTransmission to humansHumans encounter infection ‘in the wild’ (hunting, trapping, trekking, farming)Humans encounter infection in domestic settings / households (poverty, low levels hygiene)Deliberate release…?
4Distribution of plague cases by country, 2013 Global plague cases:2013: 859 cases (136 deaths)Distribution of plague cases by country, 2013
5Distribution of plague cases reported to WHO, 2000-2009
6Plague in South-East Asia India: Pneumonic plague outbreak in Himanchal Pradesh in Feb 2002 and bubonic plague in Uttarkashi in Oct 2004Indonesia: Pasuruan district of East Java in Feb 2007Myanmar: 1994Nepal: 1968Plague is a notifiable disease in Bhutan, India, Indonesia, Maldives, Myanmar and Sri Lanka
7Plague Incubation period Period of communicability Susceptibility 1-7 daysPeriod of communicabilityFleas may remain infective for monthsBubonic plague not normally transmitted human-to-human unless there is direct contact with pusPneumonic plague may be highly communicable if there is overcrowding and cool temperaturesSusceptibilityHumans are normally susceptibleImmunity after infection may not protect against a new infection
8Plague Clinical presentation and course of illness Treatment Diagnosis Initial signs and symptoms may be non-specific with fever, chills, malaise, myalgia nausea, sore throat and headacheLymphadenitis often develops at the site of inoculation (bubonic plague), e.g. a bite on the leg may lead to development of buboes in the inguinal area (groin)Septicaemic plague may follow infection and may be associated with DIC.Involvement of the lungs results in pneumonia and this may lead to secondary pneumonic plagueWith secondary pneumonic plague, transmission can occur human-to-human leading to localized outbreaks or devastating epidemicsIf untreated, for bubonic plague the case fatality rate is 50-60%Untreated septicaemic or pneumonic plague are normally fatalTreatmentAntibiotics (streptomycin, gentamicin, tetracyclines, chloramphenicol)DiagnosisClinical: signs , symptoms and an exposure history (hunting for marmots in Central Asia)Laboratory …..
9World Health Organization 12 April 2017Bubonic plagueBuboes usually in groin as most ppl get bitten on the leg. When on neck prob bitten during sleep.Bubo very painful.
10Plague Preventive / control measures Rodent controlWear gloves when handling wild animals (i.e. when hunting)Vaccine..?Should not be only the protectionAdverse reactions and unproven efficacy…Isolate individuals with pneumonic plague and implement infection control measuresConsider chemoprophylaxis for people sharing a house with a case, or contacts of pneumonic plagueQuarantine is not generally effective - and may induce panicWhy is laboratory diagnosis / confirmation important?Although clinical presentation may be typical, any rare event needs confirmationMay be part of an outbreakConfirmation will lead to specific treatment and control measuresConfirm antibiotic sensitivity
11Early detection and confirmation in remote areas Pneumonic plague outbreakZobia, DRC, 2005alertInternational team on the fieldCollection kits and Rapid tests, but with training !
12Anthrax Causative Agent When infections occur Distribution Reservoir Bacillus anthracisWhen infections occurPrimarily a disease of herbivores, humans are incidental hostsInfrequent and sporadicOccupational hazard of workers who process hides, wool, hair (especially goats)Deliberate release..?DistributionSub-Saharan Africa, Asia, South / Central America, South / Eastern EuropeReservoirNormally herbivores (domestic and wild)Dried or processed skins may harbour spores for years (important is spread of disease)
13Anthrax Transmission Incubation period Period of communicability Animals shed bacilli in blood through haemorrhaging at the time of deathCutaneous infection normally requires a pre-existing break in the skinIntestinal anthrax acquired through eating poorly cooked meatInhalational anthrax through inhalation of spores through ‘risky industrial processes’Incubation periodTypically 1-7 days, although it can be much longerPeriod of communicabilityHuman-to-human transmission is very rare (never reported for inhalational or intestinal disease)SusceptibilityImmunity may be partial (second attacks can occur)
14Anthrax Clinical presentation and course of illness Cutaneous More than 95% human infections are cutaneous – present with itching, followed by a lesion that becomes papular, then vesicular and then develops over 2-6 days into a depressed black ‘eschar’ with surrounding oedemaPain is unusualTypically on exposed areas of the body: involvement of the face / neck may lead to airway obstructionIntestinalIntestinal anthrax is rare and difficult to recognize – associated with outbreaksAbdominal distress accompanied by pain, nausea and vomiting, fever, septicaemia and deathInhalationalInitially mild, then Fever, malaise, mild cough, chest pain, acute respiratory distress, and eventually death
16Anthrax Treatment Diagnosis Preventive / control measures Ciprofloxacin, alternatives are doxycycline and amoxycillinDiagnosisClinical: signs , symptoms and an exposure / occupational historyLaboratory …..Preventive / control measuresPrevent in animals (vaccination of livestock in endemic regions)Education of people with occupational risk , control dust in ‘at-risk’ industrial settingsVaccination available for laboratory workers at high riskIsolation not needed for human cases (standard precautions)Why is laboratory diagnosis / confirmation important?Rare disease, specific treatment available – implications for animal healthMay be part of an outbreak
17West Nile Virus Causative Agent When infections occur Distribution Through the bite of an infected mosquito (that has also bitten an infected bird in an endemic area)Risk of human infection probably depends on levels of native immunity in wild birdsDistributionAfrica, Southern Europe, Central & East Asia, (including India)Introduced recently into the Americas (through New York)ReservoirSusceptible wild birds
19West Nile Virus Transmission Incubation period Rare cases of human infection through trans-placental transmission, organ transplantation and blood transfusionIncubation period5-15 daysPeriod of communicabilityHumans not normally infectious to other humans (virus not detectable in blood after onset of disease)SusceptibilityDisease most common in infancy and old age – severity increase with ageInfection thought to result in immunity
20West Nile Virus Clinical presentation and course of illness Treatment Most infections asymptomaticMild case have fever with headache, or occasionally aseptic meningitisSevere infections present with acute onset of severe headache, high fever, meningeal signs, altered mental state, and occasional acute flaccid paralysisCase fatality rate up to 25% for encephalitisTreatmentSupportiveDiagnosisClinical: (encephalitis with acute flaccid paralysis is quite rare)Laboratory…
21West Nile Virus Preventive / control measures Control of mosquitoesPrevention of mosquito bitesSpraying aircraft arriving from endemic areas?Why is laboratory diagnosis / confirmation important?Important to differentiate from other infectious / non-infectious causes of acute neurological disease (some of which may have specific treatmentMay be part of an outbreakAllows institution of control measures
22Leptospirosis Causative Agent When infections occur? Distribution Pathogenic Leptospires are spirochetes that belong to seven main species, with many subtypes…When infections occur?Mostly exposure to water contaminated by rat urineOccupational hazard for farmers, veterinarians, sewer workers, military (and others)Outbreaks associated with floodingDistributionWorldwide, except in polar regionsEndemic in rural farming areas and urban settings ( especially with unplanned development)ReservoirMaintained in genital tract and renal tubules of wild and domestic animalsSerovars are adapted to one or more animal species (dogs, swine and cattle as well as rats)
23Geographical distribution of leptospirosis Fort Brag FeverRice FieldLeptospirosisCane cutter’s diseaseMud FeverSwine herd’s diseaseSeven day feverHas been found wherever it has been looked for
25Leptospirosis Transmission Incubation period Period of communicability Contact of skin (especially if broken) or mucosal membranes with contaminated water or vegetationOccasionally through ingestion or inhalation of droplet aerosolsIncubation period5-14 days, (range of 2-30 days)Period of communicabilityDirect human-to-human transmission is very rareSusceptibilityHumans are generally susceptible, infection provide serovar-specific immunity
26Leptospirosis Clinical presentation and course of illness Treatment Two phases – 1.] leptospiraemic and 2.] convalescent (may be separated by 3-4 days, or be absent)1.] Early phase illness abrupt onset of high fever, myalgia, headache, nausea, vomiting, abdominal pain, diarrhoea, rash. Conjunctival suffusion seen in 30%2.] Late phase illness occurs 4-9 days after onset includes prolonged fever and systemic complications including jaundice, renal failure, bleeding, hypotension, pulmonary haemorrhage, myocarditis, meningitisCase fatality rates approximately 10% for acute renal failure and 50% for pulmonaryTreatmentAntibioticsSupportiveDiagnosisClinical can be difficult, but conjunctival suffusion is said to be pathognomicLaboratory….
27Leptospirosis Preventive / control measures Rodent control…Education – especially for those at occupational risk, or during floodsNo need to isolate patientsWhy is laboratory diagnosis / confirmation important?Early clinical diagnosis may be difficult, but specific treatment availableEarly detection of complicationsMay be part of an outbreakSerological classification may provide useful epidemiological informationWHO perspectiveDevelopment of Regional Strategic Framework for Prevention and Control of Leptospirosis in the South East Asia RegionSupport establishment of National Leptospirosis Reference Laboratory and laboratory networkingStrengthen capacity building for clinical case management in Member States
28Dengue Causative Agent When infections occur Distribution Reservoir Flavivirus - types 1-5When infections occurBite of infected mosquitoes (during the day)DistributionEndemic in most tropical countriesPrevalence / incidence may be increasingDistribution may be changing as a result of climate changeReservoirHuman / mosquito cycle in tropical urban areasMonkey / mosquito cycle may serve as a reservoir in some areas
29Average annual number of dengue and severe dengue cases reported to WHO in 1955–2007, and no. of cases reported, 2008–2010
33Dengue Transmission Incubation period Period of communicability Bite of infected mosquitoes – mainly Aedes aegypti, but also albopictusIncubation period3-14 days, commonly 4-7 daysPeriod of communicabilityNo direct human-to-human transmissionHumans are infective for mosquitoes during high viraemiaSusceptibilitySusceptibility universal in humans, but illness may be milder in childrenRecovery provides serotype-specific immunity, but may make disease worse if infection occurs with another serotype
34Vectors for transmission Aedes aegypti Aedes albopictus
35Percent of dengue cases by age group, Thailand (2002 – 2011)
36Dengue Clinical presentation and course of illness Treatment Diagnosis Supportive, including oral rehydrationAspirin should not be usedCareful fluid resuscitation is very importantTreatmentSupportive, but management of i.v. fluids is very importantDiagnosisClinical: early clinical diagnosis is important, but may be difficult. The tourniquet test is helpful, but is a relatively late signLaboratory…
37Dengue Preventive / control measures Mosquito controlPreventive educationNo need to isolate patientsWhy is laboratory diagnosis / confirmation important?Differentiates from other infections that have specific treatmentFacilitates supportive treatment of dengue May indicate an outbreak / upsurge of casesAllows institution of control measuresWHO perspectiveThe Asia- Pacific Dengue Partnership (APDP) was set up in March 2006 to support and facilitate effective implementation of prevention and control.In 2007, the South-East Asia and the Western Pacific Regions jointly formulated the Bi-Regional Dengue Strategic Plan, endorsed by the RC in 2008.
38Raising Awareness: ASEAN Dengue Day Observed every 15th of JuneSimultaneous activities in key cities of the ASEAN countries