CONTENT INTRODUCTION NEED OF REVERSE COLD CHAIN SURVEILLANCE STANDARDS CLASSIFICATION SCHEME STANDARDS FOR SAMPLE COLLECTION STORATGE AND TRANSPORT CONDITIONS REPORTING CRITERIA INNOVATIONS
Reverse Cold C hain The process of maintaining the cold chain when heat sensitive items are stored and transported in the reverse direction i.e. upward from the clinic to a depot or laboratory.
Reverse Cold Chain-WHO “ If a cold chain is what you call the transport chain that goes from a laboratory to the field – where vaccines must be kept at a certain temperature from the moment they are produced, until they are administered in order for them to work – a reverse cold chain is the process of stool samples that need to be tested getting back to the laboratory from the field at certain temperatures so that the virus that might be in the sample will still be identifiable .”
Why reverse cold chain? Poliomyelitis is targeted for eradication. Highly sensitive surveillance for acute flaccid paralysis (AFP), including immediate case investigation, and specimen collection are critical for documenting the absence of poliovirus circulation for polio-free certification When any case of acute flaccid paralysis is found anywhere in the world, stool samples from the affected child must be transported carefully to the laboratory so that they can be tested to identify whether the poliovirus was the cause.
Surveillance S tandards of Poliomyelitis As per WHO Clinical case definition Any child under 15 years of age with AFP* or any person of any age with paralytic illness if polio is suspected Case classification Suspected case: A case that meets the clinical case definition Confirmed case
Final C lassification S cheme for AFP Cases
Standards for Sample collection Collect two samples 24-48 hours apart and within 14 days of the onset of paralysis Volume of specimen must be adequate(approximately 8-10g ) A ppropriate documentation (i.e. laboratory request form) Sample must be in g ood condition, i.e. with no leakage or desiccation Evidence that the reverse cold chain has been maintained (presence of ice or temperature indicator )
Specimen-Based Data Unique identifier Specimen number: 1 = first specimen; 2 = second specimen; 3 = other; 9 = unknown Date of onset of paralysis Date of last OPV dose Date of collection of stool specimen Date stool specimen sent to laboratory Date stool specimen received in laboratory Condition of stool: 1 = good; 2 = poor; 9 = unknown Date final culture results sent from laboratory to EPI(Expanded Program on Immunization)
Rules for Specimen Storage and Transport Poliovirus is sensitive to heat, therefore After collection, the specimens must be placed immediately in a refrigerator or, for shipment, in a cold box at 0–8°C between frozen ice packs. Aim for the specimens to arrive at the laboratory within 72 hours of collection. If this is not possible, the specimens must be frozen (at -20°C) and then shipped frozen, preferably with dry ice or with cold packs that have also been frozen at -20°C. T ry to limit repeated freezing and thawing to a minimum. This process of keeping the specimen refrigerated or frozen is called a “reverse cold chain”.
Remember Avoid storing samples in refrigerators or cold boxes used for vaccines or medicines. If separate storage is unavoidable, seal specimens in 2-3 layers of plastic bags and separate them properly from vaccines.
Diagrammatic R epresentation 30-60 ml faeces container with external screw cap. Sealed polyethylene bag to hold faeces containers. Sealed polyethylene bag to hold report form. Absorbent material (cotton wool absorbs 8-10 times its own weight ). Icepacks obtainable from national EPI. High-density (30-35 kgs /m3) polystyrene (small bubbles and firm when squeezed). Infectious substance label. Outer carton of double-ply corrugated cardboard or plastic.
Reporting Criteria Aggregated data on AFP cases should be included in routine monthly surveillance reports Designated reporting sites at all levels should report at a specified frequency (e.g. weekly or monthly) even if there are zero cases (often referred to as "zero reporting") All outbreaks should be investigated immediately All AFP cases under 15 years of age or with paralytic illness at an age where polio is suspected should be reported immediately and investigated within 48 hours Active surveillance: Regular weekly visits should be made to selected reporting sites that are most likely to admit acute flaccid paralysis patients (e.g. major hospitals, physiotherapy centers) to look for unreported AFP cases
Innovations in the reverse cold chain Introduction of continual temperature recording probes known as ‘ Log Tags ’ to track specimens during their journey to the lab . Incentives are paid for informants who report a case.