U1DS2SP3 - 20250505

Spatial vs. Temporal Distribution of Ebola

  • Spatial refers to the arrangement of something in space, the pattern it forms, the space it occupies, and its locations.
  • Temporal refers to the distribution of something across time.
  • The 2014-2016 Ebola outbreak in West Africa serves as a key example for studying spatial and temporal distribution.

2014-2016 Ebola Outbreak

  • The outbreak began in December 2013 in Guinea.
  • Confirmed as Ebola on March 21, 2014.
  • Quickly spread to bordering countries: Liberia and Sierra Leone.
  • MSF (Médecins Sans Frontières) deployed teams to Guinea and Liberia.
  • By April, 603 deaths were reported.
  • MSF described the outbreak as unprecedented, with the epidemic spreading faster than international response.
  • June: MSF declared the epidemic out of control.
  • July: Death toll rose to 670.
  • August: WHO (World Health Organization) declared Ebola an international public health emergency.
  • September: Approximately 2,300 deaths with 600 new patients each week.
  • WHO admitted the epidemic was out of control.
  • MSF appealed to the UN for immediate deployment of civilian and military assets.
  • The UN Security Council called for an emergency response.
  • This outbreak was the worst ever recorded, surpassing all previous Ebola deaths in the past 38 years.
  • September: The international community began to respond, with noticeable implementation by November.
  • February 2014: Over 24,000 cases and 10,000 deaths recorded; MSF deployed over 3,800 staff.
  • January 2015: The epidemic began to slow down.
  • December 2014: Research began for treatments, diagnostics, and vaccines.
  • Approximately 500 health professionals, including 14 MSF workers, died.
  • Health care systems in affected countries were at risk of collapsing.
  • July 11, 2015: End of the epidemic declared in Sierra Leone.
  • November: Last identified patient in Guinea left the treatment center.
  • January 14, 2016: End of the epidemic declared in Liberia, marking the official end of the outbreak.
  • MSF shifted focus to providing care for survivors.

Spatial Distribution of Ebola

  • Describe: Provide characteristics and main features without explaining why.
  • Focus on where Ebola was located and the duration of its spread.
  • Generally isolated mainly to the African continent.
  • Isolated incidences occurred in the USA, Spain, and Italy, largely due to health care workers returning from Africa or exposed travelers.
  • Outbreaks of Ebola Reston virus (different from Zaire strain) occurred in monkeys and pigs in Asia (Philippines and China).
  • Imported outbreaks of Reston virus observed in monkeys used in labs in the USA and Italy.
  • Most concern in Central Africa (around DRC) and West Africa.
  • The 2014-2016 outbreak in West Africa was the first time the region had experienced the disease.
  • The West African outbreak (Sierra Leone, Liberia, and Guinea) had the highest number of cases ever recorded, with 10,000+ cases.
  • Zaire Ebola virus is largely distributed in Central Africa, particularly around the DRC and Congo.

Temporal Distribution of Ebola

  • Trends in Ebola's spread over time.
  • First discovered in 1976 in Zaire (now DRC).
  • XIA strain tends to be the highest and has the highest fatality rate (88% when first discovered).
  • Outbreaks were generally around Central Africa (DRC, Gabon).
  • Uganda has had numerous outbreaks.
  • 1976-2023 data shows a significant spike during the 2014-2016 outbreak.
  • Over 28,000 cases reported, with over 11,000 deaths, resulting in a fatality rate of about 40%.
  • Guinea had a fatality rate of around 67%.
  • Sierra Leone had the highest amount of deaths, followed by Liberia.
  • The outbreak began in Guinea and spread to Sierra Leone and Liberia.
  • Prior to the 2014-2016 outbreak, the effects on other countries were minimal; during the outbreak, cases appeared in Italy, USA, and Spain.
  • In the US, four people contracted it, and one person died (25% fatality rate).

Summary of Temporal Distribution

  • Approximately 30 outbreaks since 1976 up to 2023.
  • Total of over 30,000 reported cases and more than 12,600 deaths.
  • The number of cases often increases in the last quarter of an outbreak due to reduced diligence in health care and infection management.
  • When Ebola hit West Africa, it was initially mistaken for malaria or flu conditions.
  • Outbreaks vary in frequency, roughly every 5-7 years, but can range from 1 year to longer periods.

Ebola Outbreak Frequency and Contributing Factors

  • Large outbreaks occur on average every 7-10 years.
  • Smaller outbreaks can happen more frequently.
  • Vaccines have varying success rates in preventing Ebola or lessening symptoms.
  • Access to vaccines is a significant issue.
  • COVID-19 vaccines provide a similar scenario, reducing symptom severity without necessarily preventing infection.
  • Population growth, slow economic development, and climate change contribute to more regular outbreaks, particularly in Western and Central Africa.
  • Increased temperature and rainfall favor fruit bat populations, increasing the risk of transmission.