Technorati tags: Ebola, Congo, haemorrhagic dysentery, medical,
I posted before about the Ebola outbreak in the Congo. Now new cases have been reported an confirmed, which brings the total of confirmed cases on 24. However since April this year over 170 people have been killed of Ebola like haemorrhagic fever, more than 400 people have fallen sick with these symptoms.
The last Ebola outbreak in the DR of Congo was in 1995, 316 people fell sick and 245 were killed.
Since my medical background (med student) and my interest in infectious diseases including how the body fights against these diseases, i will try to explain something about this virus and what it causes.
The virus
The first outbreak of the Ebola virus occurred in 1976 in June and July in central Africa, than in august a second outbreak started in DR of Congo (former Zaire). From both the outbreaks a virus was isolated and called Ebola after a small river in Zaire. The Ebola virus and the very similar Marburg virus are classified as Filoviruses. Filoviruses have a single-stranded RNA genome (for who is familiar with this).
Transmission and epidemiology
Ebola can infect humans and other primates. So far no reservoir has been detected but recently a study suggested that fruit bats might play an important role. In this study they found three bath species that had symptomless infections with the virus. The transmission occurs mainly through direct contact with infected blood or other body fluids. Contact with the bodies of dead patients was found to be an additional factor. During an outbreak the virus is so lethal that it eliminates the susceptible population before it can spread extensively.
Clinical features
The average incubation in the previous outbreaks was circa 7 days, and the mortality rate was about 80%. Main duration between onset of the disease and death was 10 days.
The disease starts of with flu-like symptoms as headache and myalgia (= muscle pain). Fever nausea, vomiting and diarrhoea, often dysenteric, occur in a few days. Conjunctival injection, maculopapular rash and sore throat with marked pain on swallowing present relatively early in the disease as well. The rash starts towards the end of the first week on flanks an in inguinal and auxiliary regions, then it spreads rapidly ( in hours) over the whole body apart from the face. This rash is easily seen on the white skin, but a lot harder on a black skin. Bleeding from mucosa and puncture sites, anuria ( absent of urine production), hiccup and tachypnoea are features most often followed by dead in days.
The dysentery and haemorrhage (bleeding) is why this is called Ebola haemorrhagic dysentery. The bleeding is caused by the breakdown of endothelial cells (these are cells of a blood vessel) which leads to vascular injury. The widespread haemorrhage can lead to oedema (fluid “escapes” from the blood vessels and adds up in tissues) and hypovolemic shock. Other severe tissue damage is caused in the liver, spleen, lymph nodes and lungs.
Laboratory diagnosis
ELISA and PCR are used for this. By clicking on the words you will be linked to Wikipedia for an explanation of these techniques.
Management
Quarantine of patients and protection of health workers and family members is essential in the treatment of Ebola haemorrhagic fever. Use paracetamol and not aspirin or other NSAID as antipyretic (= anti fever). Fluid intake and nutrition should be maintained and blood transfusion given when patient is anaemic. However, in an endemic situation or low resource setting there might be very little that can be offered. So far no antiviral agents or vaccine are effective in humans.
Here three pictures. Note these are not mine, by cliking on the links you go to the site that originally posted them.
The rash caused by the Ebola virus. http://www.nlm.nih.gov/medlineplus/ency/imagepages/17160.htm
http://commons.wikimedia.org/wiki/Image:7042_lores-Ebola-Zaire-CDC_Photo.jpg
http://en.epochtimes.com/news/7-9-12/59688.html
Resources:
- * Ebola virus: from discovery to vaccine. Heinz Feldmann1, Steven Jones2, Hans-Dieter Klenk3 & Hans-Joachim Schnittler4. Nature Reviews Immunology 3, 677-685 (August 2003)
- * Textbook of medicine. RL Shouami, J Moxham. 4th edition, reprinted 2004. By Churchill livingstone.
- * Medical Microbiology. PR Murray, KS Rosenthal, GS Kobayashi, MA Pfaller. 4th edition 2002. By Mosby