Lineamientos Estandarizados para la Vigilancia Epidemiológica y Diagnóstico por Laboratorio de Fiebre Chikungunya

Objectives

Provide a national, standardised framework for epidemiological surveillance and laboratory diagnosis of chikungunya, enabling sensitive case detection, notification, investigation, laboratory confirmation, estimation, follow-up and timely public-health action across Mexico.[1][2][3][4]The framework addresses transmission by Aedes aegypti and Aedes albopictus, recognises acute, subacute and chronic illness, and supports surveillance in settings where chikungunya circulates alone or alongside dengue.[2][5]

• Establish common operational definitions for suspected, confirmed and discarded cases, combining clinical and epidemiological criteria with virological or serological laboratory confirmation.[3]
• Strengthen case, outbreak and death surveillance, including complete case records, differential diagnosis, outbreak investigation, mortality review and epidemiological analysis to guide prevention, control and mitigation.[4][6][7]
• Estimate transmission burden where universal laboratory testing is not feasible, using laboratory-confirmed cases and positivity-based extrapolation from sampled suspected chikungunya and dengue-related case groups.[5][8][4]
• Enhance laboratory capacity through a national reference function that supports reliable diagnosis, referral services, quality assurance, diagnostic algorithms, operational research, technological development and continuous workforce training.[9][10]
• Support vector prevention and control, health promotion and inter-institutional and intersectoral coordination through timely, accurate diagnostic and surveillance information.[11][7][12]
• Maintain standardised documentary tools for clinical investigation, routine notifications, outbreak analysis, control actions and death surveillance, including data on clinical progression, laboratory findings, hospitalisation, outcomes, geography and population characteristics.[13][14][15][16]

Implementation

Implement surveillance through linked local, jurisdictional or delegated, state and national levels, supported by the National Public Health Laboratory Network, state public health laboratories and the National Institute of Epidemiological Diagnosis and Reference.[4][17][9][12]Governance uses jurisdictional, state and national epidemiological surveillance committees, including COJUVE, CEVE and CONAVE or equivalent bodies, to review and resolve cases, outbreaks and deaths.[6][11][18]

• Detect and notify suspected cases immediately at health facilities; verify the case definition, provide care and referral advice, complete epidemiological investigation forms, maintain registers, report through the Weekly Report of New Cases of Diseases, and update records as clinical, epidemiological, laboratory and imaging evidence becomes available.[4][19][17]
• Collect serum from all eligible suspected cases before circulation is established, then sample 5% of operationally suspected cases once circulation is identified; in areas without recognised circulation, test 100% of strictly suspected cases.[3][5][19]
• Apply stage-specific diagnosis, using real-time reverse-transcription polymerase chain reaction during approximately the first five days of fever and immunoglobulin M testing from day six, including MAC enzyme-linked immunosorbent assay at the reference laboratory where applicable.[3][19][20][21]
• Integrate dengue testing and co-infection surveillance by processing dengue-compatible cases through the dengue algorithm, testing defined samples for chikungunya, and applying reciprocal testing to selected chikungunya- and dengue-positive specimens.[5][8][21][22]
• Manage specimens through documented collection, identification, triple packaging, leak-proof containers, absorbent material and a cold chain of 2 to 8°C; reject inadequately identified, contaminated, insufficient, poorly documented, delayed or temperature-compromised samples.[23][24]
• Coordinate laboratory referral and quality assurance by using state laboratories for initial testing and sending specified positive and negative samples to the national reference laboratory for confirmation, quality control, genotyping, sequencing, serum banking and external performance assessment.[10][12]
• Validate notifications and records at jurisdictional and state levels; enter information into the specialised chikungunya surveillance system, transmit databases weekly, oversee specimen transport, issue results to medical units and disseminate epidemiological alerts and recommendations.[17][11][18]
• Investigate outbreaks within 48 hours of notification, notify them within 24 hours, analyse person, time and place, identify probable sources and transmission mechanisms, document control actions, and close outbreaks after two incubation periods without locally acquired cases, specified as 30 days.[6][18][15][25]
• Review suspected deaths through the appropriate surveillance committees, submit clinical files within 48 hours where required, complete committee review within 15 days, and transmit death certificates and mortality-surveillance reports to national level within four weeks.[19][6][18]
• Monitor performance monthly, or more frequently where committees consider necessary, using indicators for notification within 24 hours, timely classification, sample rejection and laboratory reception.[26]Reference values include 100% timely notification, 80 to 100% classification within 10 or 12 working days according to specimen timing, fewer than 10% rejected samples, and at least 90% laboratory sample reception.[26]
• Maintain epidemiological profiles at jurisdictional, state and national levels covering epidemic curves, affected areas and groups, sampling, positivity, entomological indices where applicable, hospitalisation, mortality, case-fatality, outbreak studies, data quality and compliance with committee agreements.[11][7][26][9]

Monitoring & Evaluation

The guideline establishes an integrated chikungunya surveillance, laboratory-confirmation, case-estimation and accountability system across local, jurisdictional, state and national levels. It combines immediate notification, standardised case investigation, laboratory quality assurance, routine data transmission, outbreak and death review, and monthly performance assessment to support timely prevention and control action.[2][4][7][9]

• Monitor suspected and confirmed cases through immediate notification, epidemiological investigation forms, case registers, the Weekly Report of New Cases of Diseases and the Unified Automated Epidemiological Surveillance System, using Epi-Key 146 for chikungunya.[4][17]
• Apply standard case definitions and laboratory findings to classify cases as confirmed or discarded, and update records as clinical, epidemiological, laboratory and imaging information becomes available.[3][4][17]
• Estimate transmission-area case totals by extrapolating positivity from sampled operationally suspected chikungunya cases and dengue-negative specimens to relevant unsampled dengue and chikungunya case groups; include potential co-infections where dengue and chikungunya circulate together.[5][8]
• Maintain epidemiological profiles at jurisdictional, state and national levels, covering epidemic curves, affected areas and groups, sampling, positivity and, at state and jurisdictional levels, entomological indices.[11][7][26]
• Transmit jurisdictional databases weekly to state level, send the state chikungunya database weekly on Mondays, and immediately notify cases to the Directorate General of Epidemiology.[17][11]
• Monitor data quality by validating case, outbreak and death records; checking consistency across information subsystems; and correcting omissions identified through supervision.[17][26][9]
• Track specimen quality through compliance with the suspected-case definition, specimen identification, packaging, documentation, cold-chain maintenance and laboratory acceptance criteria.[19][17][23][24]
• Measure specified surveillance indicators monthly by institution and operational level, or more frequently when surveillance committees consider this necessary.[6][26]
• Assess timely notification, timely classification, laboratory rejection and sample-reception performance against reference values of 100% notification within 24 hours; 80 to 100% classification within 10 working days for samples collected in the first five days of illness; 80 to 100% classification within 12 working days for samples collected between days six and twelve; less than 10% rejected samples; and at least 90% sample reception meeting the laboratory standard.[26]
• Complete final classification within 10 working days for specimens collected during the first five days of fever, or within 12 working days for specimens collected from days six to twelve and processed by immunoglobulin M capture enzyme-linked immunosorbent assay at the Institute of Epidemiological Diagnosis and Reference; permit subsequent committee ratification or amendment.[17]
• Apply laboratory turnaround standards of three working days for real-time reverse-transcription polymerase chain reaction and commercial immunoglobulin M enzyme-linked immunosorbent assay at state public health laboratories, seven working days for reference immunoglobulin M capture enzyme-linked immunosorbent assay at the Institute of Epidemiological Diagnosis and Reference, and five working days for reverse-transcription polymerase chain reaction on necropsy specimens.[20][12][21]
• Issue laboratory results immediately and within 24 hours of obtaining them, while maintaining the applicable service-standard turnaround times.[12]
• Conduct external laboratory quality assessment, initially send all positive molecular and commercial serological samples for quality control, and allow reporting release after 100% concordance has been achieved.[9][12][21]
• Send all commercial serology-negative samples to the national reference laboratory for confirmation by the reference method, and use concordance findings to revise the proportion of negative samples selected for further assessment.[12][21]
• Notify outbreaks within 24 hours, begin investigation within 48 hours, and conclude an outbreak after two incubation periods without locally acquired cases, specified as 30 days.[6][18]
• Escalate outbreak information through successive administrative levels, investigate clusters of two or more associated cases in a delimited geographical area, and document person, time, place, symptoms, transmission mechanisms, control actions, attack rates and case-fatality rates.[19][15][25]
• Review suspected chikungunya deaths through jurisdictional, state or national surveillance committees, with reviews generally completed within 15 days and unresolved federal-entity reviews resolved nationally within 10 working days.[6][18][7]
• Submit death certificates and mortality-surveillance reports to national level within four weeks, and use investigation forms to confirm or correct causes of death and associated International Classification of Diseases, tenth revision coding.[18][16]
• Hold surveillance committees responsible for reviewing and resolving cases, outbreaks and deaths, monitoring compliance with committee agreements, and reorienting action through alerts, recommendations and supervision.[6][11][7][9]

Costing & Financing

The material requires management of resources for epidemiological surveillance, laboratory diagnosis, specimen transport, supervision, training and outbreak response, but provides no explicit costing framework, budget figures, allocations, funding sources, resource-mobilisation targets, funding gaps or economic assumptions.[6][7][9][24]

• Manage surveillance resources at jurisdictional and state levels, including capacity for case and outbreak investigation, data validation, laboratory coordination and staff supervision.[6][11][18]
• Maintain laboratory inputs and capacity for diagnostic testing, quality assurance, specimen referral and cold-chain transport; some state laboratories are noted to lack the necessary capacity and supplies for diagnosis.[3][23][24]
• Support national and state laboratory-network functions, including training, equipment oversight, external quality assessment, diagnostic algorithm development and operational research.[9][10]
• Provide no quantified financial information for the specified surveillance and laboratory activities, preventing assessment of affordability, funding adequacy or financing gaps.[1][2][27][21][22]