Numbers

"If I sit silently, I have sinned."
- Mohammed Mossadegh

I arrived home a week ago yesterday. This is day 8 of my 21-day direct active monitoring. My last contact with a patient with Ebola virus disease (EVD) was 13 days ago. Schieffelin and colleagues (2014) estimated that the incubation period (time from exposure to the virus to onset of symptoms) for EVD in Sierra Leone was 6 to 12 days. The WHO Ebola Response Team (2014) estimated the mean (average) incubation period to be 11.4 days. My risk of becoming infected with ebolavirus while wearing personal protective equipment (PPE) was low and my certainty that I am not infected increases with each passing day.

Unlike some of my colleagues who live in other states, I am not "quarantined" and no restrictions on my movements have been imposed by either the Washington State Department of Health or my local health department - my employer. Yesterday was my first day back at the health department since I left for the CDC Ebola safety training seven weeks ago. I was surprised the first time someone extended a hand for me to shake, a gesture that is discouraged during an epidemic of EVD.

Holly suggested that I post more stories about the patients I saw in Sierra Leone. The problem is that I really don't know the stories of most of our patients. We received very little information about our patients at the time they were admitted and most of my time in the confirmed ward was spent attending to people who were usually too sick to talk. I had only enough time to make small talk with the survivors who were waiting to be discharged. The only story I have to tell is my own.

Then there are the stories that the numbers tell us.

Baize et al. (2014) traced the Ebola epidemic in West Africa to a 2-year-old child in Guinea who died from the disease December 6, 2013. With the exception of a single human case of Taï Forest ebolavirus from a chimpanzee in Ivory Coast in 1994, there had never been an outbreak of EVD in West Africa.

On March 10^th of this year, the World Health Organization (WHO) was notified of an outbreak of an unknown infectious disease characterized by fever, vomiting, and diarrhea in Guinea. A few days later, Zaire ebolavirus was identified in blood from patients who were hospitalized with the disease. The disease spread to Liberia in March and to Sierra Leone in May. On August 8^th, the WHO declared the Ebola epidemic in West Africa a Public Health Emergency of International Concern. At that time, 1,779 cases and 961 deaths due to EVD had been reported to WHO. By the end of the month, the number of cases and deaths exceeded the total numbers of cases and deaths from all previous EVD epidemics combined.

CDC

 The WHO Ebola Response Team (2014) wrote, "Between March and July 2014, the reproduction number in Guinea fluctuated around the threshold value of 1, suggesting that modest further intervention efforts at that point could have achieved control."

The interventions used to contain an outbreak of EVD are the same as those used for other communicable diseases. The challenge has been implementing those strategies in places with very limited health care resources.

Country	Nurses and midwives per 1,000 population	Physicians per 1,000 population
Guinea	0.511	0.1
Liberia	0.274	0.014
Sierra Leone	0.166	0.022
United States of America	9.815	2.452
World Health Organization (2014)

Many health care providers in Ebola-affected areas were infected and died because of inadequate supplies of PPE. Some health workers fled out of fear of becoming infected. Because health care workers are now focusing their efforts on the Ebola response, routine health care services have been interrupted. Obstetric and midwifery services are unavailable to many women because of the high risk of Ebola transmission during childbirth.

This epidemic is not over. The Sierra Leone Ministry of Health and Sanitation estimated that the crude reproduction number for EVD in that country remains above 1, which means that every person with EVD can be expected to infect at least one other person. Transmission of the disease will be sustained until the reproduction number drops below one.



Ministry of Health and Sanitation, Republic of Sierra Leone

 

Number of new Ebola virus disease cases reported, by epidemiologic week — three countries, West Africa, March 29–November 30, 2014 (CDC)

 

Number of new cases of Ebola virus disease reported — Guinea, Liberia, and Sierra Leone, November 9–30, 2014 (CDC)

I started this blog nearly three years ago. On October 14th of this year, a week after my first post on Ebola virus disease (EVD), this blog had 10,000 page views. Now there are over 13,000 page views. Roughly a quarter of all of the hits on this blog have happened in the last 11 weeks.

 

It seems that what I began as my effort to keep my friends and family informed about my work in Sierra Leone got the attention of far more people than I had anticipated. I was encouraged to know that there were so many people reading this blog and am very grateful for the support that I have received from people who have read my posts.

As the title suggests, this blog was intended to be a forum for discussions about vaccines and vaccine-preventable diseases. I don't mean to minimize the importance of the current Ebola epidemic, but I will end this post by bringing the discussion back to vaccine-preventable diseases.

This epidemic dwarfs all previous EVD epidemics. This should serve as a warning that every EVD epidemic deserves an immediate and decisive response. As I write this, there have been a total of 19,463 cases and EVD and 7,573 deaths in Guinea, Liberia, and Sierra Leone.

 

 

In 2009, there were an estimated 79,292 cases of meningococcal disease in the African Meningitis Belt. The World Health Organization estimates that there were 145,700 deaths from measles in 2013. There were 610 cases of measles in the U.S. between January 1 and November 29, 2014, the highest number of cases since measles was eliminated from the U.S. Most of cases of measles in the U.S. are in people who have not been vaccinated against the disease and most are associated with importation of the virus from countries with low measles immunization coverage.

On the other hand, these numbers are small compared to the millions of deaths due to liver disease prevented by routine hepatitis B vaccination in China (Hadler et al., 2013).

The current EVD epidemic began as a small outbreak in a remote part of Africa and became an international public health emergency. Yet, there are tens of thousands more deaths from vaccine-preventable diseases every year than there have been deaths from EVD since the disease was first identified 38 years ago. Those deaths deserve our attention too.

Merry Christmas!



Andrew with his Grandpa Esvelt

References

Baize, S., Pannetier, D., Oestereich, L., Rieger, T., Koivogui, L., Magassouba, N., et al. (2014). Emergence of Zaire Ebola virus disease in Guinea. New England Journal of Medicine, 371(15),1418-1425. doi:10.1056/NEJMoa1404505.

Bernstein, L. (September 20, 2014). With Ebola crippling the health system, Liberians die of routine medical services. Washington Post. http://www.washingtonpost.com/world/africa/with-ebola-crippling-the-health-system-liberians-die-of-routine-medical-problems/2014/09/20/727dcfbe-400b-11e4-b03f-de718edeb92f_story.html.

Briand, S., Bertherat, E., Cox, P., Formenty, P., Kieny, M-P., Myhre, J. K., et al. (2014). The international Ebola emergency. New England Journal of Medicine, 371(13), 1180-1183. doi:10.1056/NEJMp1409858.

Boozary, A. S., Farmer, P. E., & Jha, A. K. (2014). The Ebola outbreak, fragile health systems, and quality as a cure. JAMA, 312(18), 1859-1960. doi:10.1001/jama.2014.14387.

Centers for Disease Control and Prevention. (June 6, 2014). Measles – United States, January 1 – May 23, 2014. Morbidity and Mortality Weekly Report, 63(22), 496-499. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6322a4.htm.

Centers for Disease Control and Prevention. (October 10, 2014). Assessment of Ebola virus disease, health care infrastructure, and preparedness – four counties, Southeastern Liberia, August 2014. Morbidity and Mortality Weekly Report, 63(40), 891-893. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6340a3.htm.

Centers for Disease Control and Prevention. (September 26, 2014). Estimating the future number of cases in the Ebola epidemic – Liberia and Sierra Leone, 2014-2015. Morbidity and Mortality Weekly Report, 63(03), 1-14. http://www.cdc.gov/mmwr/preview/mmwrhtml/su6303a1.htm.

Centers for Disease Control and Prevention. (December 12, 2014). Ebola virus disease in health care workers – Sierra Leone, 2014. Morbidity and Mortality Weekly Report, 63(49), 1168-1171. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6349a6.htm.

Centers for Disease Control and Prevention. (December 12, 2014). Rapid assessment of Ebola infection prevention and control needs – six districts, Sierra Leone, October 2014. Morbidity and Mortality Weekly Report, 63(49), 1172-1174. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6349a7.htm.

Centers for Disease Control and Prevention. (December 19, 2014). Update: Ebola virus disease epidemic – West Africa, December 2014. Morbidity and Mortality Weekly Report, 63(50), 1199-1201. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6350a4.htm.

Doucleff, M. (November 18, 2014). Dangerous deliveries: Ebola leaves moms and babies without care. NPR. http://www.npr.org/blogs/goatsandsoda/2014/11/18/364179795/dangerous-deliveries-ebola-devastates-womens-health-in-liberia.

Gire, S. K., Goba, A., Anderson, K. G,. Sealfon, R. S. G., Park, D. J., Kanneh, L., et al. (2014). Genomic surveillance elucidates Ebola virus origin and transmission during the 2014 outbreak. Science, 345(6202), 1369-1372. doi:10.1126/science.1259657.

Hadler, S. C., Fuqiang, C., Averhoff, F., Taylor, T., Fuzhen, W., Li, L., et al. (2013). The impact of hepatitis B vaccine in China and in the China GAVI Project. Vaccine, 31(Supple. 9), J66-J72. doi:10.1016/j.vaccine.2013.03.043.

Ministry of Health and Sanitation, Republic of Sierra Leone. (6 December 2014). Weekly Ebola surveillance report. http://health.gov.sl/?p=1692.

Schieffelin, J. S., Shaffer, J. G., Goba, A., Gbakie, M., Gire, S. K., Colubri, A., et al. (2014). Clinical illness and outcomes in patients with Ebola in Sierra Leone. New England Journal of Medicine, 371(22), 2092-2100. doi:10.1056/NEJMoa1411680

World Health Organization. (2014). Number of suspected meningitis cases and deaths reported: highlight on 2009 epidemiological season. http://www.who.int/gho/epidemic_diseases/meningitis/suspected_cases_deaths_2009_text/en.

World Health Organization. (2014). WHO warns that progress towards eliminating measles has stalled. http://www.who.int/mediacentre/news/releases/2014/eliminating-measles/en.

World Health Organization Ebola Response Team. (2014). Ebola virus disease in West Africa – the first 9 months of the epidemic and forward projections. New England Journal of Medicine, 371(16), 1481-1495. doi:10.1056/NEJMoa1411100.