Yellow Fever

Around late 19th and early 20th centuries the ports of Rio de Janeiro and Santos were avoided by the main shipping companies because they were known as fever-infested swamps. Enter Oswaldo Cruz, born in São Luiz do Paraitinga, São Paulo, even nowadays a very, very small place. Shortly after, his father, a doctor, was transferred to Rio de Janeiro, where young Oswaldo pursued medical studies in the National Faculty of Medicine there, later specializing in Bacteriology at the Pasteur Institute in Paris. Upon his return from Europe, the Port of Santos was devastated by an epidemic of bubonic plague. In 1903 he was appointed to a role equivalent to Health Minister today. After setting up an institute to produce anti-plague serum, he initiated historic sanitation campaigns, and through the extermination of rats, whose lice transmitted the disease, the incidence of bubonic plague fell in a few months. During the same period, when fighting yellow fever, Oswaldo Cruz faced various problems. A large section of doctors and the population believed that the disease was transmitted through contact with clothing, sweat, blood and secretions of sufferers. He, however, believed in another theory: the transmitter of yellow fever was the mosquito. He therefore suspended disinfection activities, and put in place sanitation measures with brigades who visited houses, backyards, gardens and streets to eliminate the insects, and prevent the persistence of stagnant water, a breeding place for mosquitoes. Those actions provoked a violent public reaction, but by 1907 yellow fever had been eradicated in Rio de Janeiro. Shamefully the disease is back one hundred years later.

Yellow fever is a viral infection transmitted by a bite from infected mosquitoes most commonly found in parts of South America and Africa. When transmitted to humans, the virus can damage the liver and other organs, and can be potentially fatal. Mosquitoes that breed in the jungle can also transmit yellow fever to monkeys, who in addition to humans, are also a host to the disease. The name comes from two of its most obvious symptoms, fever and the yellowing of the skin. Symptoms appear three to six days after exposure to the virus. A infection typically has three phases. In the first phase, symptoms are generally non-specific, and cannot be distinguished from other viral infections, such as fever, chills, headache, muscle aches, and vomiting. They last from three to four days, and in most people, disappear. The next phase is remission, which lasts for 48 hours. Patients improve. The majority recover. Unfortunately a third, more toxic phase of infection occurs for 15 to 25% of patients. A condition called viral hemorrhagic fever can develop with internal bleeding, high fever and damage to the liver, kidneys and the circulatory system. Up to 50% of people who reach this phase die. Yellow fever is diagnosed by symptoms, recent travel activity and blood tests. Medical treatment focuses on easing symptoms, as there is no cure for the viral infection itself. Hospitalization is often needed. As there is no cure, prevention is critical. Vaccination is advised for adults and children over age 9 months living in countries with a known risk of yellow fever. Vaccination is not advised for everyone. As the vaccine is produced from an attenuated virus, it can cause serious adverse effects in certain people. Therefore, people who have a compromised immune system, such as from HIV, or who have cancer or thymus gland problems, who have had treatments that disrupt the immune system, such as steroids or cancer treatment, or who have had a life-threatening allergic reaction to eggs, chicken, gelatin, are advised not to take the vaccine. Pregnant women, children younger than 9 months, and people aged 65 or older are not supposed to be vaccinated. Other measures are advised for people living in areas where exposure to the virus is possible, such as using insect repellent for mosquitoes on exposed skin, covering arms, hands, legs and head to protect from bites, using screens on doors and windows, and mosquito netting over beds to keep mosquitoes away. People are also advised to avoid outdoors during peak mosquito hours (dusk to dawn). Let us keep this infection at bay!

MICHAEL ROY SMITH, M.D. 

MOBILE ECHOCARDIOGRAPHY                                 

Phone: 99183-2093      

E-mail: mrsmith@terra.com.br