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Team:HZAU-China/Project/Rabies
From 2013.igem.org
1.The epidemiology of Rabies
Rabies is widely distributed in the globe and only a few countries are free of the disease. Many animal species such as fox, bat and dogs are involved in transmission of the disease. Over 55000 people die of rabies per year and more than 95% deaths are caused by dogs and 99% occur in Asia and Africa. Every year more than 7 million people are exposed to it.
2.The ways to eliminate rabies in some countries
Mass vaccination of dog and appropriate human post-exposure prophylaxis are powerful ways to control rabies.
The table shows the success of some countries to control rabies via mass vaccination of dogs.
3.Burden of rabies in Africa and Asia
Rabies has become a growing problem in Africa and Asia over the past three decades. The reasons are obviously. The density of dogs rapidly increased in rural populations and the vaccination coverage is not reach 70%. Meanwhile the density and mobility of human populations are growing.
Post-exposure prophylaxis places a substantial economic burden in Africa and Asia. It contains not only the high costs of vaccine, but also considerable loss of travel and income. The total cost of post-exposure prophylaxis accounts for 5.8% of annual per capital gross national income in Africa ($40 per one) and 3.9% ($49 per one) in Asia. In fact a bite from an uncertain rabid dog will cause great distress, often with months of anxiety. People are more afraid of rabies than malaria in Tanzania. It is hard to use money to quantify the influence of rabies on human.
In fact we can control rabies in Africa and Asia simply by increasing mass vaccination coverage of dogs. However, sustainability mass vaccination of dogs is clearly a big challenge in rural Africa and Asia. If the vaccination coverage of dogs is temporary, rabies will reoccur rapidly. A good example comes from Tanzanian. The country had controlled rabies from 1998 to 2001, but the vaccination coverage declined from 2001 to 2003. Which resulted in a new rabies epidemic. The human exposures are six times more in 2003 than previous years.
The picture shows the burden of rabies.
4.Rabies vaccine
Purified cell culture and embryonated egg-based rabies vaccines have been proved to be safe and useful in preventing rabies. It has been administered to millions of people worldwide both for pre and post exposure prophylaxis. Another kind of vaccine is Nerve tissue vaccines which will induce adverse reactions and the curative effect is not good. Nerve tissue vaccine has been suggested by WHO for discontinuation of production. But in Asia and Latin America, people still use it for post-exposure prophylaxis.
5.Rabies structure
The following is the description of rabies virus from WIKIPEDIA. For more details please visit http://en.wikipedia.org/wiki/Rabies_virus
“The rabies virus is a neurotropic virus that causes fatal disease in human and animals. Rabies transmission can occur through the saliva of animals.
The rabies virus has a cylindrical morphology and is the type species of the Lyssa virus genus of the Rhabdoviridae family. These viruses are enveloped and have a single stranded RNA genome with negative-sense. The genetic information is packaged as a ribonucleoprotein complex in which RNA is tightly bound by the viral nucleoprotein. The RNA genome of the virus encodes five genes whose order is highly conserved. These genes code for nucleoprotein (N), phosphoprotein (P), matrix protein (M), glycoprotein (G) and the viral RNA polymerase (L).The complete genome sequences range from 11,615 to 11,966 nt in length.”
Because of containing the neutralizing epitopes which are the targets of vaccine-induced immunity, the glycoprotein can stimulate the organism to produce antibody against Rabies.
Reference
1. Cleaveland S, Kaare M, Knobel D, et al. Canine vaccination‐providing broader benefits for disease control. VetMicrobiol, 2006; 117, 43‐50.
2. Shwiff S, Hampson K et al. Potential economic benefits of eliminating canine rabies. Antiviral Research, 2013;98, 352-256.
3. WHO expert Consultation on Rabies: second report, WHO technical report series; no.982.
