A

• Alert Levels: In InfoDengue, alerts are issued in a stepwise system of levels. The yellow level indicates environmental conditions favorable for outbreaks of arboviruses (dengue, chikungunya, zika), requiring increased attention and preventive action; the orange level indicates sustained transmission, meaning cases are growing exponentially and could lead to an epidemic, calling for immediate control measures; and the red level indicates dengue notifications are high compared to historical patterns, requiring urgent public health response.

• Arbovirus Vector Mosquitoes: The mosquitoes Aedes aegypti and Aedes albopictus are blood-feeding insects belonging to the Culicidae family and the Aedes genus. They transmit arboviruses such as dengue, Zika, chikungunya, and yellow fever. Their biological characteristics favor virus transmission, including short life cycles and multiple blood meals.

C

• Chikungunya: Chikungunya is a febrile infectious disease caused by the Chikungunya virus (CHIKV), transmitted by Aedes mosquitoes. It is characterized by fever and intense joint pain and has been circulating in Brazil since 2015.

• CHIKV – Chikungunya Virus: A virus of the Alphavirus genus transmitted mainly by Aedes aegypti and Aedes albopictus. Infection causes sudden fever, severe joint pain, fatigue, and rash, and may evolve into chronic joint disease.

• Climatic Receptivity: Indicator that assesses environmental conditions, especially temperature and humidity, favorable to arbovirus transmission. InfoDengue uses meteorological data to anticipate risk and issue alerts.

• Confirmed Cases: Arboviral disease cases with definitive laboratory or epidemiological confirmation after investigation of suspected or probable cases.

• Control Diagram: A graphical epidemiological tool equivalent to the endemic channel, used to monitor disease incidence over time and identify outbreaks by comparing observed and expected values.

D

• Dengue: An acute, systemic, self-limiting febrile disease that can progress to severe forms. Most dengue-related deaths are preventable with timely and adequate healthcare.

• DENV – Dengue Virus: A Flavivirus with four serotypes (DENV-1 to DENV-4), transmitted by Aedes mosquitoes. Infection with one serotype provides immunity only to that type.

• Discarded Cases: Suspected or probable arboviral cases that are ruled out after investigation due to negative tests, alternative diagnoses, or incompatible epidemiological criteria.

E

• Early Warning: A notice generated before a public health event. In InfoDengue, warnings use climate, case data, and statistical methods to classify risk levels (yellow, orange, red).

• Early Symptoms: Initial, often nonspecific signs of disease such as fever, headache, fatigue, or muscle pain, essential for early diagnosis and prevention of complications.

• Endemic Channel: A tool describing the typical seasonal pattern of a disease based on historical data, used to detect deviations and potential epidemics.

• Epidemic: Occurrence of disease cases above expected levels for a specific population, place, and time period.

• Epidemic Threshold: A statistically defined limit above which disease occurrence suggests an epidemic, often calculated using the Moving Epidemic Method (MEM).

• Estimated Cases: The estimated number of disease cases for a given period, calculated using nowcasting models applied to notification data.

• Estimated Incidence: Projected incidence rate based on estimated new cases and adjusted for underreporting or data gaps.

F

• Forecasting: The process of predicting future disease scenarios based on historical and current data, supporting planning and prevention actions in public health.

I

• Incidence: The number of new disease cases occurring in a defined population over a specific period, expressed as cumulative incidence or incidence rate.

M

• MEM (Moving Epidemic Method): A statistical method that identifies the start, intensity, and duration of epidemics by comparing current data with historical patterns.

N

• Nowcasting: A statistical technique that estimates the true number of cases in real time by correcting delays in disease notification systems.

O

• Outbreak: The occurrence of two or more epidemiologically linked cases in a defined time and place, requiring rapid investigation and control.

P

• Probable Cases: Suspected arboviral cases with strong epidemiological links, even without immediate laboratory confirmation.

R

• Reported Cases: The number of cases officially recorded in national notification systems based on clinical and epidemiological criteria.

• Rt – Time-varying Reproduction Number: Indicator that measures disease transmission intensity over time. Sustained Rt above 1 indicates ongoing transmission.

• R₀ – Basic Reproduction Number: Measure of the maximum transmission potential of a disease in a fully susceptible population.

S

• Severe Dengue: A clinical worsening of dengue characterized by warning signs such as abdominal pain, bleeding, hypotension, and respiratory distress, requiring urgent care.

• SINAN: Brazil’s Information System for Notifiable Diseases, used to record and monitor suspected and confirmed cases nationwide.

• Serotype: A distinct variant of a virus defined by antigenic properties. Dengue has four serotypes, and infection with one does not confer full immunity to others.