Traveling to the tropics has many health hazards that many travelers don’t expect.  Therefore, travelers to the tropics must take their precautions before traveling to avoid picking up an infectious disease.  There are many infectious diseases that are endemic in the tropics such as:  yellow fever, malaria and hepatitis A.  This essay will look at the causes, symptoms, transmission and prevention of yellow fever.

Yellow fever is an acute infectious disease, endemic in tropical Africa and America.  It is caused by a group B arbovirus transmitted by mosquitoes(1).

Yellow fever is caused by a group B arbovirus which occurs for short irregular periods and which is widespread in parts of Africa and tropical America(2).  The yellow fever virus is classified as a prototype of flavivirus taxonomic group.  It is spherical in shape, enveloped and very small in size (about 38 nm) (3).  The yellow fever virus is found in monkeys and it is transmitted to man by mosquitoes(2).

Most conditions with yellow fever have  mild symptoms which do not  last for a long time and the patient can  recover completely.  In severe cases there are two phases the patient undergoes:  the first attack and the second attack.  In the first attack the patient will have a fever and some times bleeding and then the temperature will fall and become normal again for few days.  Then, the second attack begins with higher fever, more bleeding, massive proteinuria and renal failure.  In addition, there are major symptoms for severe cases which are:  black vomit (hematemesis) and jaundice (which give yellow fever its name).  Moreover, if there is no complete recovery with severe cases of yellow fever death is likely(4).

Yellow fever is divided into two types according to its distribution.  The two types are:  Urban yellow fever and Jungle yellow fever.  The two types have the same immunological and clinical properties, but they differ in the type of vector and the source of infection (1).  Urban yellow fever , which is mostly spread outside the jungle, is transmitted by Aedes aegypti mosquito which transmits it from an infected person to another healthy person.  In jungle yellow fever , which is mostly spread inside the jungle, there is a variation between the vector and the source of infection.  For example, in tropical South America yellow fever the  transmission is  by Aedes aegypti mosquitoes from monkeys to man.  While, in tropical Africa Aedes Africanus mosquitoes transmit yellow fever from monkey to monkey and then Aedes simpsoni mosquitoes transmit it from monkey to man(4).

 During the period of infection, yellow fever should be carefully watched and checked in order to be treated .  The patient with yellow fever should have  complete bed rest and take some drugs such as:  mild sedatives, nonsalicylate analgesics and antiemetics.  If yellow fever becomes very  acute , for example if the patient gets severe vomiting and heamorrhage, supportive care must be taken and attention should be given to the fluid and electrolyte balance in order to control the disease(3).

Yellow fever can be prevented in two ways.  Firstly, control of mosquito distribution that transmit the disease.  Next, vaccination against flavivirus(4).  There are two vaccines available for yellow fever which are 17D vaccine and Darkar vaccine.  The 17D vaccine is made from a virus originally  isolated in West Africa.  The Darkar vaccine is made from a neurotropic virus which is grown in mouse brains.  Both  vaccines are made of viruses and give very good results(1).

In conclusion, yellow fever is an acute infectious disease caused by a prototype of flavivirus.  In general, yellow fever has  mild symptoms from which patients can completely recover.  In some cases there are severe symptoms such as high fever, black vomit and jaundice.  In mild cases yellow fever can be treated by complete bed rest and taking specific drugs.  While in severe cases supportive care must be taken.  Yellow fever can be prevented by control of mosquitoes that transmit the disease and vaccination against flavivirus.