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Working with the laboratory during outbreak investigations Integrated Disease Surveillance Programme (IDSP) district surveillance officers (DSO) course.

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Presentation on theme: "Working with the laboratory during outbreak investigations Integrated Disease Surveillance Programme (IDSP) district surveillance officers (DSO) course."— Presentation transcript:

1 Working with the laboratory during outbreak investigations Integrated Disease Surveillance Programme (IDSP) district surveillance officers (DSO) course

2 2 Preliminary question to the group What is your experience in working with the laboratory on outbreak investigations? If yes, what difficulties did you face? What would you like to learn about working with a laboratory?

3 3 Outline of this session 1.Communicating with the laboratory 2.Specimen collection, storage and transportation 3.Biosafety 4.Quality assurance

4 4 Participation of laboratory specialists in field investigation Presence in the field: The ideal option  Laboratory specialist provide real time input  Time consuming, expensive  Most useful in difficult situations Remote participation: The common option  Involve the laboratory early  Exchange information  Most efficient in routine situations Communication

5 5 Communicating with the laboratory Share initial information at the earliest about the investigation  Epidemiological characteristics  Suspected pathogens (differential diagnosis) Organize communication on an ongoing basis  Identify focal person, obtain contact information  Generate outbreak number  Provide updates  Send the final epidemiological report Communication

6 6 General framework to decide what kind of specimens to take What are the suspected pathogens? What tests are used to diagnose the suspected pathogens? What is the stage of the illness?  No virus isolation at a late stage of illness Communication

7 7 Elements to consider when choosing a laboratory Location Referral protocols Capacity Biosafety level Quality, accreditation or certification  (e.g., Polio) Credibility, track record with your team Costs Communication

8 8 Whom to sample during a classical outbreak? Typical cases  Should represent the majority of the specimens Untreated patients  Without antibiotics Cases likely to carry the pathogen  Children Atypical cases  Few specimens Healthy contacts  Few specimens Collection

9 9 When to sample? Isolation of agent, PCR or antigen:  At the earliest  Before anti-microbial administration For antibody estimation:  Ideally two paired specimens At earliest After days  Alternately, one specimen 4-5 weeks after onset Collection

10 10 How many specimens to take? Ensure sufficient number of specimens (At least 20)  Avoid sampling error  Obtain reliable results Avoid overwhelming the laboratory with excessive specimens Repeat sampling in some case-patients  Acute and convalescent sera  Exploration of chronic carriage  Intermittent shedding (e.g., Stool microscopy for parasites)  Unknown etiology Collection

11 11 WHO guide Rule of thumb regarding the number of specimens to take during a cholera outbreak 10 specimens to confirm the outbreak Five specimens per week during the outbreak Specimens at the end to confirm that the outbreak is over Collection

12 12 Transport medium Allows organisms to survive under adverse conditions Does not allow organisms to proliferate Available for bacteria  e.g., Cary Blair Available for viruses  Virus transport media (VTM) Collection

13 13 What is a Viral Transport Medium? Sterile buffered solution (Pink coloured) containing antibiotics for preservation of viruses Used in the collection of specimens for viral isolation and testing Save the viruses from drying  Nutrient, glycerol Prevents specimen from drying out Prevents bacterial and fungus growth Prepared in the lab or commercially obtained Storage for short periods at ºC Collection

14 14 To avoiding hemolysis for blood specimens, avoid: Fine needles Forced suction of blood with syringe Unclean tube (residual detergents) Shaking tube vigorously Forced expulsion of the blood through needle Freezing / thawing of blood High speed centrifugation before complete clotting Collection

15 15 Vacutainers Vacuum tube with rubber stopper mounted on a needle system  Tubes may be changed for collection of different tubes for different purposes Smooth blood flow, lower risk of hemolysis Reduces risk of spillage Collection

16 16 Collecting and handling blood for smears Collection  Take capillary blood from finger prick (Lancet)  Make smear on clean glass slide  Dry and fix with methanol or other fixative Handling and transportation  Transport slides within 24 hours  Do not refrigerate May alter the morphology of the cells Collection

17 17 Collecting blood for cultures Collect within mn of fever Aseptic technique Quantity  0.5 – 2 ml venous blood for infants  2 – 5 ml venous blood for children  5 – 10 ml venous blood for adults Take three sets of blood culture when suspecting bacterial endocarditis Collection

18 18 Handling and transporting blood for cultures Collect into blood culture bottles with infusion broth  Change the needle to inoculate the broth Travel at ambient temperature Collection

19 19 Collecting serum Collect venous blood in a sterile test tube Let specimen clot for 30 minutes at ambient temperature Place at 4-8oC for clot retraction for at least 1-2 hours Centrifuge at 1500 RPM for 5-10 min Separate the serum from the clot with pipette / micro-pipette Collection

20 20 Handling and transporting serum Transport at 4-8oC if transport lasts less than 10 days Freeze at -20oC if storage for weeks or months before processing and shipment to reference laboratory  Ship frozen Avoid repeated freeze-thaw cycles  Destroy IgM (e.g., Measles diagnosis) Collection

21 21 Collection  Lumbar puncture Aseptic conditions Trained person  Sterile tubes Handling and transportation  For bacteria, transport at ambient temperature or preferably in trans-isolate medium (pre-warmed to °C before inoculation)  For viruses, transport at 4- 8 o C for up to 48 hours or at -70 o C for longer duration Collecting and handling cerebrospinal fluid Trans-isolate biphasic medium Collection

22 22 Collecting and handling stool specimens Take freshly passed stool specimen  Avoid collecting specimen from a bed pan Collect specimen in a sterile container (if available) or clean container (not cleaned with a disinfectant) Collection

23 23 Rectal swabs Advantage  Convenient  Adapted to small children, debilitated patients and other situation where voided stool specimen collection is not feasible Drawbacks  No macroscopic assessment possible  Less material available Not recommended for viruses Collection

24 24 Collecting stool specimens for viruses Timing  Within 48 hours of onset Specimen amount and size  At least 5-10 ml fresh stool from patients (and controls) Method  Fresh stool unmixed with urines in clean, dry and sterile container Storage  Refrigerate at 4oC. Do not freeze  Store at -15oC for antigen detection and protein chain reaction (PCR) Transport  4oC (Do not freeze)  Dry ice for antigen detection and PCR Collection

25 25 Collecting stool specimens for bacteria Timing  During active phase Specimen amount and size  Fresh specimens and two swabs from patients, controls and carriers (if indicated) Method  In Cary-Blair medium (+ specimen without transport medium for antigen detection / PCR) Storage  Refrigerate at 4oC if testing within 48 hours, -70oC if longer Collection

26 26 Collecting stool specimens for parasites Timing  As soon as possible after onset Specimen amount and size  At least 3 x 5-10 ml fresh stool from patients (and controls) Method  Mixed with 10% formalin or polyvinyl chloride, 3 parts stool to 1 part preservative  Unpreserved specimens for antigen detection and PCR Storage  Refrigerate at 4oC  Store at -15oC for antigen detection and PCR Transport  4oC (Do not freeze)  Dry ice for antigen detection and PCR Collection

27 27 Collecting a sputum Instruct patient to take a deep breath and cough up sputum directly into a wide-mouth sterile container Avoid saliva or postnasal discharge Minimum volume should be about 1 ml Collection

28 28 Handling and transportation of respiratory specimens All respiratory specimens except sputum are transported in appropriate media  Amie’s or Stuart’s transport medium for bacteria  Viral transport medium for viruses Transport as quickly as possible to the laboratory to reduce overgrowth by oral flora For transit periods up to 24 hours  Ambient temperature for bacteria  4-8°C for viruses Collection

29 29 The label of the specimen Name: _________ Age: ______ ID number: _____ Specimen type: ______ Date, time of collection:___________ Place of collection:___________ Collection

30 30 Labeling glass slides for microscopy Label slides individually Use glass marking pencil Make sure procedure will not interfere with the staining process Each slide should bear:  Patient' name  Unique identification number  Date of collection Collection

31 31 The case investigation form: What the epidemiologist sends Patient information  Age (or date of birth), sex, complete address Clinical information  Date of onset of symptoms, clinical and immunization history, risk factors or contact history where relevant, anti- microbial drugs taken prior to specimen collection Laboratory information  Acute or convalescent specimen  Other specimens from the same patient Line listing of patients Collection

32 32 The case investigation form: What the receiving laboratory records Date and time when specimen was received Name and initials of the person receiving specimen Record of specimen quality Collection

33 33 Biosafety 1/3: Protect the patient Use single use equipment Disinfection Work in a clean, dedicated area Biosafety

34 34 Biosafety 2/3: Protect yourself Use personal protective equipment  Disposable gloves  Laboratory coats / gown  Mask  Protective eyewear / face shields if procedure is likely to generate aerosols Collect sharps immediately, in the absence of recapping in sharps container to prevent needle- stick injury Have first aid kit readily accessible Do not reuse contaminated equipment / supplies such as gloves Do not leave the specimen on the request form Collection

35 35 Biosafety 3/3: Protect others and the environment Package specimens appropriately for transport Decontaminate spills  10% bleach after wiping the surface clean Disinfect working areas for future use  1% household bleach daily Soak contaminated non-disposable equipment or materials in 1% household bleach for 5 minutes. Wash in soapy water before use and sterilize if necessary Place waste in leak-proof biohazard bags Ensure safe final management of waste Protect personnel in charge of cleaning or decontamination with protective coat and thick rubber gloves Collection

36 36 Triple-packaging of specimens: Two goals Protect the environment and the carrier Protect the specimen Collection

37 37 The basic triple packaging system: 1/3: The primary receptacle Sealed specimen container to be placed in a suitably sized plastic bag/ ziploc bag Packaged with sufficient absorbent material to absorb the entire content of the primary receptacle in case of breakage Specimens from different patients should never be sealed in the same bag Two or more sealed specimens of the same patient may be put in a larger plastic bag and sealed Collection

38 38 The basic triple packaging system: 2/3: The secondary receptacle Leak-proof secondary plastic container with screw capped lids Enclose and protect the primary receptacle(s)  Place the sealed bags containing the specimens inside secondary plastic containers  Specimens from several patients may be packed inside the same secondary plastic container Sufficient additional absorbent material used to absorb all fluid in case of breakage Collection

39 39 The basic triple packaging system: 3/3: The outer packaging Secondary packaging(s) are placed in outer shipping packaging with suitable cushioning material Outer packaging protect their contents from outside influences, such as physical damage, while in transit Resistant, high density external cover (metal, wood, fiberboard) Smallest overall external dimension  10x10 cm Collection

40 40 Refrigeration methods to obtain different temperatures 2-8 °C/4 °C  Wet ice/ice packs/domestic refrigerator -8/ -10 °C  Freezer of domestic refrigerator -20 °C  Freezer cabinet -70 °C  Deep freezer/dry ice -170/ -196 °C  Liquid Nitrogen Vaccine carriers that have been used for specimen transport must never be reused for carrying vaccines! Collection

41 41 Quality assurance Internal quality control (Continuous, concurrent control of laboratory work) External quality assessment (Retrospective and periodic assessment) Quality assurance = + Quality

42 42 Internal quality control Test request and specimen collection Test processing  Temperature  Reagent  Maintenance of equipment Reporting and using test results Collection

43 43 External quality assessment Within the state IDSP system  L1 by L2  L2 by L3 Through external agency  External quality assurance scheme for selected tests Collection

44 44 Criteria for rejection of specimens Mismatch of information on the label and the request Inappropriate transport temperature Inappropriate transport medium Insufficient quantity Leakage Excessive delay in transportation Specimen received in a fixative Dry specimen Specimen with questionable relevance Collection

45 45 Take home messages 1.Develop rapport with the laboratory 2.Collect specimen according to the guidelines and access on-line resources if needed 3.Protect the patient, yourself and others 4.You can contribute to quality assurance!

46 46 Additional reading WHO Guidelines for the collection of clinical specimens during field investigation of outbreaks IDSP bio safety manual Section 6 of operations manual Module 6 of training manual Collection


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