Rift valley fever is a viral fever which usually attacks animals but also can infect humans. The incubation period for rift valley fever is two to six days following the infection.
Causes of Rift Valley Fever
The rift valley fever is a short term or acute viral illness causing fever in humans. Rift valley fever is caused by RFVF or RFV virus which is prevalent in animals such as camels, goats, sheep, and cattle etc… the rift valley virus spreads to humans via infected mosquitoes.
Signs and Symptoms of Rift Valley Fever
The virus that causes rift valley fever usually takes 2-6 days for causing any symptoms in the body after it has entered into the body. After this period of a few days of incubation, you may develop various types of disease syndromes. There is also a possibility that you might not show any symptoms at all of the infection. Some show signs of mild fever and liver problems. The illness cause due to rift valley fever is associated with pain in back, dizziness and weakness in entire body. Most patients can recover in 2-3 days after the symptoms first appear while some can take up to one week for the symptoms to disappear.
Rift Valley Fever usually do not lead to any symptoms but its possibilities cannot be ruled out completely. About 8-10% of the patients infected with rift valley fever virus have a risk of developing severe symptoms. These symptoms are as follows:
- Ocular disease: This is a special type of disease that affects the vision of the person. It is a type of disease that causes infection in eyes. The lesions in the eye can take anywhere between 1 to 3 weeks to develop. Ocular disease results in temporary problems with vision as things appear blurred to the patient. It takes about 10-12 weeks for the vision to get back to the normal condition. However, there is special case of ocular disease in which the lesions occur in the macula (a small central part of the retina) which is particularly severe. People with these types of ocular disease have a high risk of vision loss. The loss of vision is permanent in this case.
- Encephalitis: Encephalitis is type of inflammation occurring in brain. It usually results in symptoms like seizures, coma and headache. However, it is a very rare condition that affects only one out of every 100 patients suffering from rift valley fever. The symptoms of Encephalitis can take anywhere between 1 to 4 weeks to first appear after the person shows first signs of infection. The inflammation is not fatal but it can lead to severe neurological deficits that can continue for an indefinite time period.
- Hemorrhagic fever: The rift valley fever can sometimes take a severe form resulting into hemorrhagic fever. However, it is a very rare condition that affects only one out of every 100 patients suffering from rift valley fever. It is a severe condition that can be fatal in about 50% of the cases. The first symptoms of hemorrhagic fever can be seen in 2-3 days from the infection. It usually starts with normal jaundice and then gradually developing some other symptoms including liver impairment, vomiting with traces of blood, bleeding from nose, gums and other injection sites, discharge of blood during motion etc. What makes this condition more severe is that the person can die in just 3-6 days after the first signs of hemorrhagic fever appear.
Diagnosis of Rift Valley Fever
The symptoms of rift valley fever and not very specific and thus it is very difficult to diagnose this condition through clinical tests. It can take a few days for the experts to be sure about rift valley fever as its symptoms are identical to many other diseases including viral haemorrhagic fevers such as yellow fever, typhoid, malaria, shigellosis etc.
Proper and quick diagnosis of rift valley fever requires specialized laboratories. People who are handling the sample at the laboratory are at high risk of catching infection. Thus, it is important that sample is handled with proper care. Rift Valley fever virus is contagious in nature.
Various laboratory tests available for the diagnosis of rift valley fever are as follows:
- Virus isolation by cell culture.
- RT-PCR: Reverse transcriptase polymerase chain reaction assay
- ELISA: IgG and IgM antibody enzyme-linked immunosorbent assay (ELISA)
Treatment and Vaccines for Rift Valley Fever
In general, rift valley fever is not severe and thus does not require any treatment. However, in severe cases, treatment is necessary. The most common treatment option for rift valley fever is supportive therapy.
Medical experts have also managed to develop an inactivated vaccine for rift valley fever but it is still in the experimental stage. Thus, it is not yet available commercially for general use. It will take some time for the vaccine to become available for human use.