Alerta Dengue is a nowcasting system that uses data from Twitter, epidemiological monitoring, meteorology, and entomological monitoring to provide surveillance of dengue fever in Brazil. It analyzes the number of tweets about dengue, official dengue case numbers, temperature data, and mosquito ovitrap data to assign alert levels - green for low risk, yellow for dengue season, orange for active transmission, and red for an epidemic. The system provides weekly reports and maps to track dengue activity and issue alerts.

1. ALERTA DENGUE
Support: Brazilian Ministry of Health

2. What is Alerta Dengue?
● A now casting system for surveillance of dengue fever that uses data from
● Twitter
● Epidemiological monitoring
● Meteorology
● Entomological monitoring
Epidemic
Transmission
Attention
Low risk
Meteorology
Vector Density
Dengue incidence
Oviposition
Officially notified
dengue cases
Twitter
ALERTA

3. What is Alerta Dengue?
● A now casting system for surveillance of dengue fever that uses data from
● Twitter
● Epidemiological monitoring
● Meteorology
● Entomological monitoring
Epidemic
Transmission
Attention
Low risk
Meteorology
Vector Density
Dengue incidence
Oviposition
Officially notified
dengue cases
Twitter
ALERTA

4. How does Alerta Dengue work?
Number of tweets
about dengue
Number of dengue
cases
Oviposition
activity
Minimum
temperature
Timeseries
Maps
Alert
correction of notification
delay
filter
Weekly
report

5. www.observatorio.inweb.org.br/dengue/conteudo/inicial
Observatório da dengue
(Federal University of Minas Gerais)
- geo-referenced tweets about dengue
- focused on tweets of personal experiences,
(not including tweets of dengue campaigns etc.)
- example: “I think I got dengue!”
Number of tweets about dengue

6. Number of
dengue cases
total notified
known
estimated
week
SINAN dengue (SMS RJ)
notificationdelay(days)
Notification delay
- delay of about two weeks
- increases during epidemics
-> we correct this delay by
estimating the “real” number of
dengue cases

7. Meteorological stations
→ Airports
→ www.weatherunderground.com
Minimum
Temperature

8. Entomological monitoring
- High temporal resolution (weekly or fortnightly)
- Sensitive and inexpensive option: ovitraps (photo)
- Other options: Traps for adult mosquitoes
- Not recommended: Larval surveys
Oviposition
activity
www.fiocruz.br

9. Decision model for the Dengue
Alert categories (colors)
Example for Rio de Janeiro
-> Calibration is necessary for each
location!
T24 < 3.7 days
T24 > 3.7 days
Or Rt(tweeter)>1
p(Rt >1) > 0.95
p(Inc > 1%) > 0.95
Timeseries

10. Timeseries
Epidemic
Transmission
Attention
Low risk
No risk. When the map is green, there is no or low
transmission. The conditions for the reproduction of the
mosquito and dengue transmission are not ideal.
Dengue season. At level yellow, the climatic conditions are
favorable for dengue transmission and mosquito reproduction.
The transmission of the disease is not yet significant.
Dengue transmission. At level orange, there is already a
pronounced dengue incidence, but we can still not affirm that
an epidemic will occur.
Epidemic. When the map is red, we are in an epidemic. We
have to be watchful for dengue symptoms and immediately
seek medical care when we suspect to be infected with
dengue.

11. Example Alerta Dengue Rio
http://info.dengue.mat.br
- At the moment we use the following data:
- Twitter
- Officially notified dengue cases
- Climate
- We are planning to include entomological monitoring data
- Ovitraps

12. The Alerta Dengue website: www.info.dengue.mat.br

13. The Alerta Dengue website: www.info.dengue.mat.br

14. - Already available
- Twitter
- Meteorological data
- Necessary
- Dengue cases (without patient identification, provided weekly)
DT_NOTIFIC = notification date
SEM_NOT = epidemiological week of the notification
NU_ANO = notification year
DT_SIN_PRI = date of first symptoms
DT_DIGITA = digitation date (entry in the data banc)
SEM_PRI = epidemiological week of the first symptoms
NM_BAIRRO = neighborhood of residence
ALERTA DENGUE : participation requirements

15. ALERTA DENGUE
Apoio: Ministério da Saúde