6.4.7. Alert and Response, case investigation, clusters and outbreak investigation

Day by day, the EpiU using the subsystem for Epidemiological Intelligence and Early Warning and Response (EWAR) integrates and analyzes data coming from different subsystems and sources for detecting CD cases, clusters and outbreaks, APHE, or doing the follow-up of the existing ones and disseminate information. At same time, EpiU receives information from international sources about PHEIC and epidemics or outbreaks in neighboring countries, the region, or other regions of the world.

6.4.7.1.  Case investigation

This is applied by medical doctors and family nurse practitioners initially working in HCF when detecting a suspected or confirmed CD, and coordinate with Public Health Nursing Supervisor and/or Epidemiologists when the nature and importance of the case (s) is complex. They can rule out the diagnostic or discard the outbreak if considered.

• Guidance for diagnosing a CD in the index case or contacts, should be based on the presence of fever at onset or after in the last days (10), clinical and epidemiological characteristics (see Syndromes 6.4.2.), and a blood white cell count test with abnormal levels of neutrophils, lymphocytes, or eosinophils. The sedimentation rate and C Protein abnormal levels also help.
• The absence of fever in a possible outbreak suggests a non-biological agent with exception for food poisoning by Staphylococcus and a few others. An early and positive microbiological test can define the etiology and presence of a CD outbreak.

6.4.7.2.  In an outbreak (see 6.1) 

The number of cases varies according to the disease-causing agent and conditions, and the size and type of previous and existing exposure to the agent (WHO). Outbreaks are usually caused by an infection, toxic/chemicals or less frequent by radioactive material, transmitted through person-to–person contact, animal to person contact, or from the environment or other media and has a common source of transmission.

Once an outbreak has been officially declared, appropriate resources (both human, material, and financial) will need to be mobilized to support the outbreak response by MOH, PS and CMO, who decide who are going to integrate the Outbreak Investigation Team (RRT) and how they are going to proceed. The multidisciplinary team is usually integrated by: A team leader, who should have strong epidemiologic skills, a Public Health or Infection  Control Nurse/Epidemiologist to collect and collate data and samples on cases and controls during the time of the outbreak; EHO to conduct site investigations and collect data and samples; A Health Educator coordinator for health promotion within the community affected; Laboratory support to ensure proper sample collection, preservation and transport, and confirm the etiologic or causative agent; A clinician for diagnosis and patient care and management; A spokesperson should be designated to communicate with the media and deliver messages to the public in one way; A responsible for logistics.

The team should meet with CMO before going to the field to know about the possible - confirmed outbreak and the advance working plan and coordination with different institutions; they can work in full composition in the field or not, having a place or room for meeting and the responsibility for the investigation and control of the outbreak. In this regard, we should have daily meetings to follow the study and evolution of the outbreak, the effective implementation of prevention and control measures, and preparing the daily report for MOH.

The basic components to respond to outbreaks and epidemics are (WHO): 

1. Coordination

2. RRT

3. Public Awareness (IEC) and Community engagement

4. IPC measures

5. Case management

6. Safe and dignified burials

7. Environmental risk control

8. Epidemiological surveillance, immediate reporting, case investigation and contact tracing, isolation, quarantine & segregation

9. Laboratory support: clinical, microbiology and pathology

10. Vaccination

11. Traveling and POE

12. Budget

13. Operations and logistics.

The public will be informed and aware of the existence of a threat to public health and advice on actions and prevention measures. Every effort must be employed to ensure early announcement of an outbreak to the public. An outbreak in Saint Lucia is confirmed by CMO (EpiU and other specialists) and communications to the public is done by the spokesperson.

The step-by-step process for investigation and control can be done simultaneously to reduce the timeframe from the beginning to the control.

• Verify the diagnosis and establish a case definition using the syndromes, the distribution of cases since the beginning of the first known case by place, time, and characteristics of the patients, and possible environmental factors associated (biological, chemical, physical factors, social), lab tests or other complementary tests.
• Confirm the existence of an outbreak: Tables with incidence overtime that exceeds the expected numbers, if it is not a new disease in the area, the geographical distribution of the cases, the clinical and epidemiological characteristics of the cases and complications or severity.
• Establish regular communication with the population in the affected area and the country by MOH, for prevention and control and updates about the outbreak, causes and evolution.
• Manage cases, diagnostic and testing, treatments, including ICU, isolation at home or in a HCF, IPC measures, clinical and epidemiological discharges, HCW protection.
• Active outbreak investigation, prevention, and control: Record case histories and 10 similar antecedents, contact tracing, quarantine at home or HCF, identify additional cases, define and review periodically the population and risk based on the investigation results, and formulate hypothesis. Distribute the cases systematically by place, time onset, demand of health care, and confirmation, and antecedents of exposure or contagion. Take lab samples form patients or environment to explore the causes and verify hypothesis. Design, if necessary, a case control study to explore potential causes. Define the agent, reservoir, mode of transmission and susceptibility of the (population). Use Go. Data, Epi-Info, or other for introducing data with defined variable ID for individuals and aggregate data from different sources, and integrate analysis, producing brief reports.
• Reanalyse the prevention & control measures to stop transmission and close the outbreak.
• Conduct active ongoing disease surveillance to be sure the outbreak is under control, and if can be closed after interrupted the transmission and defined the complex of causes which explained the outbreak.
• Prepare the daily and final report and closure of the outbreak using the official MOH Forms for reporting, notification, follow up and contact tracing, with a set of preventive and control measures and surveillance activities that should be further maintained.