Ebola Virus Transmission

Transcription

1 Ebola Virus Zoonotic virus bats the most likely reservoir, although species unknown Spillover event from infected wild animals (e.g., fruit bats, monkey, duiker) to humans, followed by human-human transmission 1

2 Ebola Virus Transmission Virus present in high quantity in blood, body fluids, and excreta of symptomatic Ebola Virus Disease (EVD) infected patients Opportunities for human-to-human transmission Direct contact (through broken skin or unprotected mucous membranes) with an EVD-infected patient s blood or body fluids Sharps injury (with EVD-contaminated needle or other sharp) Direct contact with the corpse of a person who died of EVD Indirect contact with an EVD-infected patient s blood or body fluids via a contaminated object Ebola can also be transmitted via contact with blood, fluids, or meat of an infected animal Limited evidence that dogs become infected with Ebola virus No reports of dogs or cats becoming sick with/transmitting Ebola 2

3 Human-to-Human Transmission Infected persons are not contagious until onset of symptoms Infectiousness of body fluids (e.g., viral load) increases as patient becomes more ill Remains from deceased infected persons are highly infectious Human-to-human transmission of Ebola virus via inhalation (aerosols) has not been demonstrated 3

4 EVD Risk Assessment Highest risk behaviours: 1. Care of bodies of those who died of EVD 2. Care for those ill with EVD 3. Cleaning of contaminated fluids/areas Unknown but considered high risk: 1. Breastfeeding from mother with EVD 2. Sexual contact with recent male EVD survivor

5 Clinical Manifestations by Organ System in West African Ebola Outbreak Organ System Clinical Manifestation General Fever (87%), fatigue (76%), arthralgia (39%), myalgia (39%) Neurological Headache (53%), confusion (13%), eye pain (8%), coma (6%) Cardiovascular Chest pain (37%), Pulmonary Cough (30%), dyspnea (23%), sore throat (22%), hiccups (11%) Gastrointestinal Vomiting (68%), diarrhea (66%), anorexia (65%), abdominal pain (44%), dysphagia (33%), jaundice (10%) Hematological Any unexplained bleeding (18%), melena/hematochezia (6%), hematemesis (4%), vaginal bleeding (3%), gingival bleeding (2%), hemoptysis (2%), epistaxis (2%), bleeding at injection site (2%), hematuria (1%), petechiae/ecchymoses (1%) Integumentary Conjunctivitis (21%), rash (6%) WHO Ebola Response team. NEJM

6 History of current outbreak First in West Africa First outbreak to reach pandemic status First outbreak to reach urban areas Complicating factors: Extreme poverty, dysfunctional healthcare systems, mistrust of government officials after years of civil conflict, delay in responding to the outbreak and local burial customs that include washing of the body after death.

7 Field Clinical Management of EVD: Supportive, but aggressive Hypovolemia and sepsis physiology Aggressive intravenous fluid resuscitation Electrolyte and acid-base abnormalities Aggressive electrolyte repletion Pain relief and sedation if neurological symptoms develop Symptomatic management of fever and gastrointestinal symptoms Avoid NSAIDS Multisystem organ failure can develop and may require (though generally not available) Oxygenation and mechanical ventilation Correction of severe coagulopathy Renal replacement therapy Reference: Fowler RA et al. Am J Respir Crit Care Med

8 Patient Recovery Patients who survive often have signs of clinical improvement by the second week of illness Associated with the development of virus-specific antibodies Antibody with neutralizing activity against Ebola persists greater than 12 years after infection No patient yet cured, though some recover Prolonged convalescence Includes arthralgia, myalgia, abdominal pain, extreme fatigue, and anorexia; many symptoms resolve by 21 months Visual disturbances including color and full-range blindness Significant arthralgia and myalgia may persist for >21 months Skin sloughing and hair loss has also been reported Neurological symptoms and dementia post-disease also recorded References: 1 WHO Ebola Response Team. NEJM 2014; 2 Feldman H & Geisbert TW. Lancet 2011; 3 Ksiazek TG et al. JID 1999; 4 Sanchez A et al. J Virol 2004; 5 Sobarzo A et al. NEJM 2013; and 6 Rowe AK et al. JID

9 EVD Cases and Deaths, 16 March 2016 Reporting Cases in past 21 days Total Cases (Suspected, Probable, and Confirmed) Confirmed Cases Total Deaths Guinea Liberia 0 10, Sierra Leone 0 14, United Kingdom Nigeria Spain Senegal United States Mali Italy TOTAL 28,642 15,254 11,316 9

10 Impacts Shattered healthcare systems further disrupted Endemic diseases unchecked: HIV, malaria, Lassa Fever. Economic dislocation Family destruction Brain drain Additional convalescent burden Need for surveillance infrastructure

11 International Response Began through efforts of charities on the ground, MSF, STC, other NGOs and religious groups Became more critical as local HCW died in early stages of outbreak World Health Organisation coordinated global response across three affected nations French took lead in Guinea, USA in Liberia, and Britain in Sierra Leone due to linguistic and historical factors New Zealand and Australia assisted British response in Sierra Leone.

12 Australia/New Zealand Response Individuals assisted in response through NGO efforts In early November Australia decided to establish an Ebola Treatment Centre in Sierra Leone, to be operated by Aspen Medical, a for-profit medical services firm Starting at roughly 30 beds, the ETC was to have an eventual capacity of 100 patients New Zealand provided support for the project though financial contributions providing for up to 24 New Zealand staff to assist in care provision British built facility.

13 Australia/New Zealand Response First patients entered in early December. Facility staffed with 4-6 expat MDs, expat nurses, 250+ total Sierra Leonean staff Hastings Airfield 2 ETC treated 216 patients, with a rough survival rate of 35% ETC trained more than 200 local staff in infection control and EVD care Facility decommissioned and site returned to Sierra Leonean government 1 May 2015 Seven New Zealanders served at ETC.

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