Manual para la Vigilancia y Control de la Fiebre Amarilla, Venezuela

Objectives

The material concerns yellow fever prevention, detection, confirmation and control in Venezuela, addressing a vaccine-preventable arboviral disease that has sylvatic and urban transmission cycles and remains relevant in tropical areas of the Americas and Africa.[1]The operational focus is to identify suspected cases and populations at risk, investigate possible transmission, guide control measures, and ensure immediate notification through the mandatory surveillance system.[2][3]A wider formal mission, long-term strategic framework, programme goals and financing strategy are not specified.[1][4]

• Characterise epidemiological risk, including three Venezuelan natural foci identified as San Camilo, southern Lake Maracaibo and Guayana, where epizootics may alternate with periods of apparent silence.[5]
• Recognise yellow fever as a disease with sylvatic transmission involving non-human primates and forest mosquitoes, and urban transmission involving Aedes aegypti; direct person-to-person transmission is not described.[6][7]
• Detect suspected cases through acute febrile illness, jaundice, haemorrhagic manifestations, relevant exposure history and clinical assessment, including differentiation from other febrile icteric-haemorrhagic illnesses.[8][9][10]
• Identify populations at risk by investigating epizootics, mapping risk areas and considering forest-related occupational, settlement, mining, agricultural, oil-exploration, displacement and migration exposures.[6][2]
• Protect populations at probable places of infection through blocking vaccination, with an operational aim of 100% vaccine coverage in the response area.[2]
• Classify investigated events as urban yellow fever, sylvatic yellow fever or discarded, using laboratory, epidemiological-link or clinical confirmation criteria.[11]

Implementation

The approach combines case-based epidemiological investigation, laboratory-supported diagnosis, vaccination response, entomological assessment, vector reduction and structured notification.[2][10][11]Surveillance is organised through the Directorate-General of Epidemiology, the National Directorate of Epidemiological Surveillance, the Surveillance Unit for Febrile Jaundice Diseases and the mandatory disease-notification system.[3]The source provides detailed forms and response activities, but does not specify a comprehensive delivery model, budgets, formal stakeholder mandates beyond named surveillance bodies, or a broader accountability framework.[12][3]

• Investigate suspected cases using the case definition, clinical and ancillary assessment, differential diagnosis, and an epidemiological history covering movements during the 15 days before symptom onset.[2][4]
• Review health services for acute febrile syndromes and retrospectively investigate unexplained febrile, icteric or haemorrhagic deaths.[2]
• Record demographic, residential, clinical, hospitalisation, laboratory and outcome information, alongside notification and investigation dates, epidemiological week and notification source.[10][11]
• Document yellow fever vaccination status, vaccination date and vaccine batch number, and register campaign delivery by location, health establishment, vaccinator, data recorder and individual recipient details.[3][4]
• Support diagnostic classification through serology, specific examinations, viral isolation, histopathology and immunohistochemistry, while recognising that specialised testing may be limited in rural, forest and suburban settings.[13][10][11]
• Distinguish severe yellow fever from malaria, leptospirosis, hepatitis B-Delta, dengue haemorrhagic fever, Latin American viral haemorrhagic fevers and Gram-negative sepsis using clinical, epidemiological and laboratory evidence.[9][14][15]
• Monitor laboratory findings relevant to severity and prognosis, including blood-count changes, coagulation factors, liver enzymes, bilirubin, urea and creatinine.[14][13]
• Investigate reports of epizootics and record animal-health and entomological signals, including monkey mortality, wild vectors such as Haemagogus and Sabethes, and the presence of Aedes aegypti.[6][4]
• Undertake urban entomological investigation where a case was exposed during viraemia, reduce vector populations, and use an Aedes infestation index above 5% as a trigger for blocking vaccination within an 800-metre radius.[2]
• Notify higher-level authorities immediately and inform health teams following detection and investigation.[2]
• Close cases by recording recovery, death or unknown outcome, including date of death where applicable, case-closure details, investigator signature and regional epidemiologist oversight.[4]

Monitoring & Evaluation

Monitoring and accountability centre on mandatory notification, structured case investigation, laboratory confirmation, entomological assessment, vaccination records, case classification and documented closure. Surveillance arrangements involve the Directorate-General of Epidemiology, the National Directorate of Epidemiological Surveillance, the Surveillance Unit for Febrile Jaundice Diseases and the mandatory disease notification system.[3]The material does not provide a consolidated monitoring and evaluation framework, routine reporting timetable, evaluation methodology or wider performance-management system.[1][12][16][17]

• Detect and investigate suspected cases through clinical assessment, ancillary examinations, differential diagnosis, epidemiological investigation and review of movements during the 15 days before symptom onset.[2][4]
• Review health-service records for acute febrile syndromes and febrile, icteric or haemorrhagic syndromes, and retrospectively investigate unexplained deaths with these features.[2]
• Apply a suspected-case definition covering acute fever of up to seven days with jaundice and at least one haemorrhagic manifestation, alongside specified exposure or vaccination-status criteria.[10]
• Record notification and investigation dates, epidemiological week, notification source, demographic and residential information, clinical presentation, hospitalisation, epidemiological history and outcome.[10][11]
• Document recent travel by date and location, including locality, parish, municipality or state and country, to establish the probable place of infection.[4]
• Record yellow fever vaccination status, vaccination date and vaccine batch number for investigated individuals.[4]
• Use serology, specific examinations, viral isolation, histopathology and immunohistochemistry as recorded laboratory evidence, alongside epidemiological-link and clinical criteria for confirmation.[10][11]
• Classify final outcomes as urban yellow fever, sylvatic yellow fever or discarded, with space to explain the classification.[11]
• Record case outcome as recovery, death or unknown, including the death date where applicable.[4]
• Close investigations through a documented closure date, observations and the name, signature and date of the responsible investigator; record regional epidemiological oversight through the epidemiologist’s name, signature and date.[4]

Surveillance also incorporates animal and vector information because yellow fever transmission may be sylvatic or urban. The investigation instrument records wild vectors such as Haemagogus and Sabethes, the presence of Aedes aegypti, and epizootics including monkey mortality.[4]The discovery of skeletons of wild primates in forests is identified as an alert signal for possible epidemics.[6]Historical surveillance evidence includes outbreaks, human cases, deaths and viral isolation in non-human primates, including a 2010 epizootic in Monagas without recorded human cases or deaths.[5][8]

• Conduct entomological surveillance for Aedes in urban locations visited during the viraemic period.[2]
• Use an infestation index above 5% as the stated trigger for blocking vaccination within an 800-metre radius.[2]
• Notify higher-level authorities immediately and inform health teams following detection and investigation.[2]
• Maintain daily vaccination registers containing location and responsible-service details, vaccinators, data recorders, vaccine-lot information and vaccinated persons’ names, sex and age group.[2][18][3]
• Monitor clinically relevant laboratory changes, including leucocyte and platelet patterns, erythrocyte sedimentation rate, fibrinogen, coagulation factors, liver enzymes, bilirubin, urea and creatinine.[14]
• Interpret higher aminotransferase concentrations as indicating greater liver injury and poorer prognosis.[14]

Laboratory and surveillance capacity may be constrained in rural, forest and suburban settings where specialised examinations are seldom undertaken because required technology may be unavailable.[13]Beyond the 100% vaccination-coverage aim for blocking vaccination, the material does not specify formal indicator definitions, denominators, reporting frequency, targets, audit processes, sanctions or public accountability arrangements.[2]

Costing & Financing

No costs, budgets, funding allocations, financing sources, funding gaps, resource-mobilisation mechanisms or economic assumptions are specified.[1][8][13][7][12][3][4]The material identifies operational activities that would require resources, but supplies no financial values or costing methodology.[7][2][18]

• Undertake vaccination activities, including blocking vaccination at the probable place of infection and daily registration of administered doses.[2][18]
• Conduct laboratory diagnosis and confirmation using serological, virological, histopathological and immunohistochemical examinations where available.[10][11]
• Carry out case investigation, retrospective death review, epidemiological mapping and identification of populations at risk.[2]
• Implement entomological investigation and vector-population reduction where urban exposure during viraemia is identified.[2]
• Address potential technology constraints affecting specialised laboratory examinations in rural, forest and suburban areas, although no investment requirement or funding source is specified.[13]

The source therefore provides no basis for estimating programme costs, unit costs, workforce requirements, vaccine procurement expenditure, laboratory expenditure, vector-control expenditure, domestic financing, donor support, affordability or funding shortfalls.[1][12][16][17][4]