The yellow fever virus (YFV) is a potentially fatal illness carried by mosquitoes in 44 countries in Africa and South America. 85% percent of those infected suffer from only the acute version of the illness, which includes a fever; chills; vomiting or nausea; and head, back and muscle aches before symptoms go away on their own.
However, 15% go on to develop a much more severe case: symptoms seem to better, then get worse instead, along with jaundice, poor kidney function, and hemorrhaging (bleeding) from the eyes, nose, and mouth and in vomit and stool. Half of all these cases result in fatalities. Symptoms appear three to six days after contraction; the initial stage lasts for three days, and death can occur within two weeks. The symptoms are similar to that of several other illness (such as malaria), so blood tests must be done for an accurate diagnosis.
Why to Get Vaccinated
There is no cure for YFV; it can only be treated symptomatically. The areas it occurs in are often poor and underdeveloped, which means the necessary testing and medical care are not always readily available. While it is very rarely seen in the United States, travelers can be subject to it from visits to the tropical regions the mosquitoes that carry it inhabit. Luckily, there is a vaccine; in fact, most travelers are required to have an International Certificate of Vaccination and Prophylaxis (obtainable upon vaccination) before being allowed into high-risk countries, or even out of those countries and into others. However, it is important to understand the vaccine and its risks before planning a trip and the subsequent antiserum injection.
Benefits of Vaccination
According to the World Health Organization, 10 days after being vaccinated, the chances of contracting yellow fever drops to less than 20%, and within 30 days, 99% of people are completely immune for their entire lives. One injection as a child is sufficient to develop this level of immunity, but experts suggest those in high-risk areas being vaccinated regularly. However, the Center for Disease Control contests that the vaccine must be administered every 10 years. This difference in opinion is probably largely due to the difference in these two organizations goals.
Vaccine Reactions
Although side effects are rare, there have been reported cases. Some people are allergic to the vaccine and have a standard reaction: hives, itching, dizziness, swelling of the face, or difficulty breathing, among other things. Less severe side effects may occur within a week of getting the vaccine, and include mild symptoms similar to those of the actual illness. The area of the vaccine (which is given subcutaneously, under the skin) may also become swollen or painful.
More serious reactions can take up to a month to appear. Reported physical symptoms include stiffness, weakness, loss of movement, trouble walking, light sensitivity, back pain, prickly feelings, flu symptoms, losing control of the bladder or bowels, trouble breathing, and difficulty swallowing or speaking. Behavioral and cognitive reactions may include memory or vision loss, feeling confused or irritable, balance and coordination issues, behavior changes, convulsions, and blackouts.
Who Should Not Be Vaccinated
People with less healthy immune systems are at the most risk for contracting YFV but also more likely to have an adverse reaction to the vaccine. They should carefully consider the chances of getting the virus versus the risks of the vaccine. People with symptomatic HIV or AIDS, a thymus disorder, or allergies to egg proteins; women who are pregnant or nursing (unless they are in an area where there is currently a YFV outbreak); and children under nine months old are advised not to be vaccinated, as the chances of having an adverse reaction are much greater in these groups than in others.
The risks of vaccination to pregnant women are not yet understood well enough for experts to be comfortable giving the injection. People over 60 are also highly recommended to carefully consider their state of health before agreeing. This is largely for travelers, however, as it is generally agreed people in high risk areas during an epidemic will fare worse if they contract yellow fever than if their bodies do not respond well to the vaccine.
