Emerging Diseases

Lecture 9: Filoviruses

9.1 Overview9.2: Outbreaks:

Marburg, N’zara, Yambuku, Reston, Kikwit, West Africa

9.3 Summary

9.1: Overview

• “Mystery” viruses• Seem to come out of nowhere• Frightening symptoms• Very lethal• A recipe for disease terror

Marburg• 1967• Laboratory animals• Mystery disease• 31 infected• Terrifying threat

Filovirus

First recorded filovirus outbreak-broughtTo Europe by imported labmonkeys

Nzara

• June-August 1976• Different strains of Ebola (Ebola Zaire/Ebola Sudan)• 151 dead/284 cases

Source of the virus-unknown!

Yambuku

Death Toll 280/318

EBO-Z surfaced shortly after the first Ebola outbreak in Sudan and killed 280 of the 318 people it infected. On September 1, 1976, four days after returning from a tour of northern Zaire, the index case, a 44 year-old male teacher at the Mission School, sought medical intervention for a febrile illness he thought to be malaria. He received a parenteral injection of chloroquine (an anti-malaria drug) from Yambuku Mission Hospital (YMH). YMH did not use disposable needles or sterilize the needles between uses. Parenteral injection was the primary mode of administering nearly all medicines, and Ebola-Zaire (EBO-Z) was quickly disseminated into the surrounding villages serviced by YMH. After 11 of its 17 staff members fell ill with EHF, YMH closed on September 30, 1976, 29 days after the index case received his injection of chloroquine. The WHO International Commission was formed on October 18th, and research teams were mobilized on October 30th. The last case of EBO-Z died on November 5, 1976. Transmission of Ebola during this outbreak occurred mainly through the use of contaminated needles to administer medicine.

Yambuku disease cowboys in action

Reston, 1989Philippine animalsAirborneLethal in monkeys but mild

in humans

US outbreak halted bymilitary before spreading

Kikwit-1995

Death toll = 244/315

Urban outbreak in Africa-Source unknown

West Africa Outbreak• Largest ever• December 2013-now• Guinea, Liberia, Sierra

Leone• Bushmeat source?• misdiagnosis

Ebola in Sierra Leone: after 4,000 deaths, outbreak all but over Teams fighting the disease in west African country say they may have seen the last cases

Case Counts*As of October 7, 2015(Updated October 9, 2015)Total Cases (Suspected, Probable, and Confirmed): 28,465Laboratory-Confirmed Cases: 15,239Total Deaths: 11,312

According to WHO’s October 7 Situation Report, there were no confirmed cases of Ebola reported in the week up to October 4. This is the first time a complete epidemiologic week has passed with no confirmed cases since March 2014. All contacts in Sierra Leone have now completed their 21-day monitoring period. However, more than 500 contacts remain under follow-up in Guinea and several high-risk contacts in both Guinea and Sierra Leone have been lost to follow-up.

9.3:Summary

Recent evidence indicates that various types of bats carry filoviruses.Human-bat contact spreads the disease to humans.