YELLOW FEVER IN BRAZIL
Olivia Burr
Dr. Kline
Global Health 310: Intro to Global Health
1 May 2017
Introduction
Yellow fever is a vector-borne disease transmitted from infected mosquitos to humans and non-human primates. Yellow Fever has turned into a global health issue today since it has been responsible for urban epidemics deviating populations of South American and African continents since the seventeenth century (Goldani, 2017). Yellow fever currently affects up to 200,000 people annually in sub-Saharan Africa and tropical South America. If infected, it is fatal in 20-50% of people with severe disease. Prevention is critical to lower disease risk and mortality (Yellow Fever Vaccine, 2013). This disease is considered a major problem today. According to the World Health Organization, “thirty-two African countries are now considered at risk for yellow fever, with a total population of 610 million people, along with more than 219 million living in urban settings (Yellow Fever, A Current Threat **Insert Year of article). It is endemic in South American countries as well as the Caribbean islands. Brazil is a country among many others in South America that is at great risk for yellow fever, due to problematic mosquito recolonization occurring in the areas as well as low immunization coverage (Yellow Fever 2016).
Signs and Symptoms
Yellow fever has a number of signs and symptoms, such as headache, jaundice, muscle pain, nausea, vomiting, and fatigue. The incubation period is 3-6 days for yellow fever. However, if someone is vaccinated, symptoms disappear in 3 to 4 days. Half of people who are unvaccinated will get this disease, have extreme symptoms, and die within 10 days (Yellow Fever 2016). The name “yellow” fever comes from the jaundice and sickly look that patients acquire when they are infected. The fatality rate among confirmed cases is 36% for yellow fever. (Beaubien 2017).
Transmission
The yellow fever virus is transmitted by a bite of an infected mosquito, more specifically, the Aedes and Haemogonous species. There are three different types of transmission cycles to contract yellow fever, which are sylvatic, intermediate, and urban (Yellow Fever, 2016). These types of transmission cycles differentiate depending on the mosquito’s habitat. Sylvatic (or jungle) yellow fever is present in tropical rainforest areas with monkeys, which act as the reservoir of the fever. When humans pass through the forest, they are likely to get bit by the infected mosquito and become infected themselves.
Intermediate yellow fever are the mosquitos that are both in the wild and in households, infecting more people at once. This transmission cycle is the most prevalent in Africa. The last transmission cycle is urban, which is “when infected people introduce the virus into heavily populated areas with high mosquito density where people have little to no immunity due to lack of vaccination” (Yellow Fever 2016). Many of these heavily populated areas in Africa or Brazil are not vaccinated, which makes the population highly susceptible to contracting yellow fever. A recent article states, “From December 2016 to February 22, 2017, a yellow fever outbreak has affected Brazil, with 1345 suspected cases, or which 215 deaths reported to Brazilian Ministry of Health” (Goldani, 2017). Most of these cases occur in males ranging from the age of 30-60 years old living in rural areas.
Reemergence of Yellow Fever
There are several factors that contribute to the re-emergence of yellow fever in Brazil. Health officials have monitored these factors over time from studying the yellow fever outbreaks closely and looking at their geographical location. This article was written by a medical researcher at the Evandro Chagas Institute (IEC) and head of the Arbovirology and Hemorrhagic Fever Section, Pedro Fernando da Costa Vasconcelos. Vasconcelos conducted a study on yellow fever in Brazil, which illustrated his thoughts and hypothesis on the emergence in previously yellow fever-free areas. This article focuses on São Paulo (Southern Brazil) and Rio Grande do Sul (Southern Brazil). Vasconcelos takes a close look at these two areas in Brazil and why they became high risk areas for yellow fever over time in 2008 and 2009. He writes, “the following factors have played a pivotal role for the reemergence of yellow fever in these areas: large susceptible human population; high prevalence of vectors and primary hosts (non-human primates); favorable climate conditions, especially increased rainfall; emergence of a new genetic lineage; and circulation of people and/or monkeys infected by virus” (Vasconcelos 2009). He continues to explain how there needs to be an effective surveillance program to ensure the country will be prepared for the next outbreak in Brazil and surrounding countries. Since this article was published, the disease surveillance in Brazil has improved tremendously from the World Health Organization and the Center for Disease Control. Collecting data, analyzing, and interpreting large volumes of data from an array of sources is essential to take the first steps to prevent health issues globally.
The first of four factors of Vasconcelos’ theory on the reemergence of yellow fever in Brazil is a susceptible population. Vaccinations used to only be available in districts where the outbreaks occurred, meaning that the majority of the population was not vaccinated. This is dangerous because yellow fever is prone to circulate to both animals and humans very quickly if an outbreak occurs. Surveillance and vaccination interventions have since then been in place to help prevent wiping out an entire population from yellow fever.
Large populations of vectors and primary hosts are the next factors in the reemergence of yellow fever. In the jungle, transmission is circulated quickly to both monkeys and people passing through. Viral multiplication in vectors causes the disease to spread rapidly (Vasconcelos 2009). The Yellow Fever Initiative took place to ensure that Brazil and other high risk countries have enough vaccines in case of an emergency epidemic. There have been strides made in all the right directions, but vaccinating each and every person in one of the largest continents comes with a tremendous amount of difficulty.
Climate conditions is another factor, since “there have been recently major climate changes especially in the state of Rio Grande do Sul, resulting in intense and prolonged conditions alternating between rainfall and drought” (Vasconcelos 2009). Studying the weather patterns is essential information for global health officials, because it is likely that climate change contributed to the reemergence in Brazil. The viral lineage is another factor, because studies have shown that genetic lineage follows a pattern within a geographical location.
Last, the reemergence of yellow fever in Brazil is due to the circulation of yellow fever virus and viremic people within Brazil. Vasconcelos writes, “people, movement and infected monkey trafficking is a compelling explanation for yellow fever reemergence in areas that have been unaffected by viral circulation for more than 40 years and that are about 1,000 km away from each other” (Vasconcelos, 2009). Increased agriculture and urbanization has made it much easier to move around within the country of Brazil, making it easy for viral infections and disease to spread rapidly. The combination of these five factors are all reasons why yellow fever is reemerging in areas of Brazil. Disease surveillance has gotten increasingly better over the last decade in managing and keeping track of all the cases, due to improved technology and education.
Population at Risk
This virus is endemic in tropical areas of Africa and Central and South America. This is because: “the population is more frequently exposed to areas and situations of risk, mainly due to their working activities” (Goldani, 2017). According to Goldani, the majority of yellow fever cases are found in Minas Gerias, which is a large inland state in southeastern Brazil. This outbreak was reported in December 2016, but more confirmed cases are bring reported in neighboring states. In response to this outbreak, health authorities are listing areas to recommend vaccination for travelers and locals.
Yellow fever is a current global health issue in much of the South American countries as well as sub-Saharan countries. An article that was written in February, 2017 states that, “the first sign of trouble was the monkeys dropping dead in the forest. Then people started getting sick and dying too” (Beaubien, 2017). This caught people’s attention because yellow fever has not been a major problem among humans and animals in Espírito Santo, a state in southeastern Brazil, since 1940. Soon after the monkeys began to die, the first human case of this outbreak was detected in December. A laboratory confirmed case detected a 44-year-old man came down with this disease on the 27th of January, 2017 in Espírito Santo, which is a more rural part of Brazil. Soon after, 2 more cases emerged, and then more followed which created high levels of uncertainty and fear in the country. According to the World Health Organization, “the total number of suspected and confirmed yellow fever cases reported is the highest reported nationwide since 2000” (Yellow Fever, Brazil 2017). Statistics have shown that, “In Brazil, since the beginning of the outbreak in December 2016 up to 20 April 2017, there were 2,900 cases of yellow fever reported (681 confirmed, 1,451 discarded, and 768 suspected under investigation), including 372 deaths (234 confirmed, 103 discarded, and 35 under investigation). The case fatality rate (CFR) is 34% among confirmed cases.” (Epidemiological Update, 2017). These numbers have been growing since April, which has caused the CDC, WHO, and other organizations to step in and help control the outbreak. This new threat of yellow fever in Brazil has caused the World Health Organization to dispatch 3.5 million doses of vaccines from its emergency stockpile in an effort to get the endemic under control.
Beaubien writes, “usually there are only a handful or at most a few dozen cases of yellow fever in Brazil, and they’re found deeper in the Amazon, not hundreds of miles to the south” (Beaubien, 2017). These cases are sylvatic, or “jungle” cases, meaning those people who work outdoors in a rural area are more prone to getting bit by a mosquito.
It is always important to be prepared for an unexpected spike in numbers from a large population like the one in Brazil. This is a global health issue because these numbers began to rise this past year, and the World Health Organization is taking action and dealing with this current outbreak and hopes to eliminate yellow fever in Brazil permanently. Both Africa and South America are the countries at highest risk of getting yellow fever compared to the rest of the world. More specifically, 47 countries in Africa and 13 countries in South America are exposed due to lack of vaccination.
Treatment
No specific treatment or cure for yellow fever exists, however, “a single dose of the 17 D live-attenuated vaccine can provide lifelong immunity within 10 days of vaccination for more than 90% of people vaccinated and within 30 days for 99% of people vaccinated” (Goldani, 2017). The yellow fever vaccination has been used in Brazil since 1937. It is well tolerated and has mild systemic side effects. In 1991, it was introduced to endemic regions for infants (Veras 2010). Since then, the vaccinations were needed throughout the whole country in Brazil in 1998, because not enough people were getting vaccinated. The vaccine is in an even higher demand in Brazil due to the rising number of cases. According to Veras, “yellow fever vaccination is recommended as part of routine in infant immunizations for all children who reside in 13 states, and for those who reside in areas considered at risk in 7 of the remaining 14 states” (Veras 2010). Routine infant immunization is highly important to prevent the spread of yellow fever in Brazil.
Prevention
There are a number of things one can do to prevent contracting yellow fever. First, it is important to cover up skin with long sleeved shirts and pants. Using bug repellent, oil of lemon or eucalyptus, or 2-undecanone all repel against mosquitos are all effective methods of prevention. (Yellow Fever in Brazil, 2017). Using permethrin-treated clothing and gear is beneficial because it will kill any insects that comes in contact with it. Stay in air-conditioned and screened-in areas while sleeping, and consider using a bed net. A bed net is a way of keeping insects from flying inside your tent if you are exposed to the outdoors, or do not have a screen door for protection. When using an out-house to go to the bathroom, always put bug repellent on before exiting the house. This is because mosquitos are most active during dawn and dusk, so if you are out during these times, this increases the likelihood of getting bitten. The final and most important prevention method is to get vaccinated if you are living in a high risk area or are planning to travel to Africa or South America.
There are a number of limitations in promoting vaccination across the country of Brazil. It is difficult to get millions of people proficiently vaccinated, due to the different outlooks people have regarding vaccinating children, and the access they have to the vaccine. According to Koïvogui, “in comparison with single people, married people or those living in civil-partnership and their families were not more likely to be vaccinated” (Koïvogui 2016). Respondents with a lower education level, as well as people who do not have an opinion, are more likely to not get vaccinated than respondents with a high education level. Koïvogui writes, “negative beliefs and attitudes towards vaccination are often result of lack of information about the benefits of vaccination. This lack of exacerbated when the education level is low” (Koïvogui 2016).
Since the launching of the Yellow Fever Initiative in 2006, there has been substantial progress in preventing the disease in the West African region. This initiative was launched by The World Health Organization and the United Nations Children’s Fund which was supported by the Global Alliance for Vaccines and Immunization, which raised upwards of 58 million dollars for the cause. The intention is to, “create a stockpile for use in epidemics and to implements preventative mass vaccination campaigns in the 12 most affected countries in West Africa (Garske 2014). The Yellow Fever Initiative has provided an adequate global supply of the vaccine to protect the world’s most vulnerable population. According to the initiative pamphlet, “each year, the global emergency vaccine stockpile has 6 million doses available the any country for emergency response” (Yellow Fever Initiative, 2006). Overall, it touches on 47 countries in Africa and central and south America, posing a risk for over 900 million people. The Yellow Fever Initiative aims to do three things according to the CDC: “ensure timely and effective response to outbreaks, reduce morbidity and mortality to the infection, and eliminate yellow fever outbreaks” (Yellow Fever Initiative, 2006).
Response
The CDC, WHO, and Relief Web and the local news post articles weekly updating the world about recent yellow fever outbreaks in Brazil and around the world. In one of the World Health Organizations most recent articles, they write about updates on yellow fever vaccination in Brazil and recommendations for international travelers. As of Match 2017, “yellow fever transmission continues to expand towards the Atlantic Coast of Brazil and areas not deemed to be at risk for yellow fever transmission prior to the revised risk assessment” (Yellow Fever, Brazil). In addition to these preventive measures, WHO and its partners also established a Yellow Fever International Coordinating Group, to “oversee the management of an emergence vaccine stockpile of 6 million doses by year” (Yellow Fever Initiative, 2006).
Public Health officials in Brazil are active about making sure everyone is vaccinated if they are living in a high-risk area, “they have launched mass vaccination campaigns in areas around where the cases have been detected” (Beaubien 2017). Between 2007 to current time, numerous vaccination campaigns have stepped into vaccinate as many people as possible in a high risk environment. The governor in Brazil announced a public health emergency to raise awareness about this issue. Beaubien writes, “the Brazilian government already has shipped 10 million doses of vaccine to five states in the south to try to step the outbreak and has ordered additional stockpiles to be used in other hot spots as needed” (Beaubien 2017). The World Health Organization has been actively overseeing the efforts made to control the outbreaks, they say that, “Latin America is now at a greater risk of urban epidemics of yellow fever than at any time in the past 50 years” (WHO). Spreading the word about the importance of vaccination is key to get the outbreak under control. Also, the World Health Organization works on making sure travelers get their vaccination before entering a high-risk country to ensure they do not develop the disease (Yellow Fever- Brazil 2017).
Conclusion
Yellow fever is a current global health issue in Brazil, and substantial progress is being made to help deal with this pressing issue. The World Health Organization, Unicef, and the Center for Disease Control and Prevention have all made tremendous efforts, including raising 58 million dollars to create the Yellow Fever Initiative. They have also organized vaccination campaigns in the high-risk countries. Although it is not possible to fully eradicate the disease due to the wildlife in South America, it can be controlled by wide spread vaccination across the country. Disease experts are now worried that yellow fever could become a part of the United States, due to frequent international travel. Although this is highly unlikely, it is important to always be prepared and aware. The World Health Organization and Center for Disease Control and Prevention are monitoring the outbreak closely. Medical epidemiologist Erin Staples says, “The yellow fever outbreak in Brazil is yet another reminder of the dangers posed by mosquito-borne diseases around the world. It is critical that nations have the capacity to quickly detect and control these outbreaks in order to decrease the illness and death and prevent the spread to other locations” (Sun 2017). When countries come together and help intervene, vaccinate and spread awareness of yellow fever across the globe, there will be much less uncertainty and a better grasp on the global health issue as a whole.
Works Cited
Beaubien, Jason. “Brazil’s Expanding Yellow Fever Outbreak Started With Monkeys” February 17th, 2017. http://www.npr.org/sections/goatsandsoda/2017/02/17/515444290/brazils- expanding-yellow-fever-outbreak-started-with-monkeys
Garske T, Van Kerkhove MD, Yactayo S, Ronveaux O, Lewis RF, Staples JE, et al. (2014) Yellow Fever in Africa: Estimating the Burden of Disease and Impact of Mass Vaccination from Outbreak and Serological Data. PLoS Med 11(5): e1001638. https://doi.org/10.1371/journal.pmed.1001638
Goldani, Luciano Z. Yellow fever outbreak in Brazil, 2017, The Brazilian Journal of Infectious Diseases, Volume 21, Issue 2, March–April 2017, Pages 123-124, ISSN 1413-8670,
International Travel and Health. World Health Organization. Updates on Yellow fever vaccination recommendations for International Travelers related to current situation in Brazil (posted 31 January 2017). http://www.who.int/ith/updates/20170214/en/.
Koïvogui, Akoï. Carbunar, Aurel. Imounga, Laure-Manuella. Laruade, Christelle . Laube, Sylvaine. Vaccination against yellow fever in French Guiana: The impact of educational level, negative beliefs and attitude towards vaccination, Travel Medicine and Infectious Disease, Volume 15, January–February 2017, Pages 37-44
Relief Web Epidemiological Update – Yellow Fever. 25 April 2017. http://reliefweb.int/report/brazil/epidemiological-update-yellow-fever-25-april-2017
Sun, Lena H. Yellow fever outbreak in Brazil worries U.S. officials. The Washington Post. March 8 2017 https://www.washingtonpost.com/news/to-your- health/wp/2017/03/08/yellow-fever-outbreak-in-brazil-worries-u-s- officials/?utm_term=.1312490bc8a2
The Yellow Fever Initiative, 2006: providing an opportunity of a lifetime, 2006. Brochure: http://www.who.int/csr/disease/yellowfev/YFIbrochure.pdf?ua=1
Vasconcelos, P.F.C. Yellow fever in Brazil: thoughts and hypotheses on the emergence in previously free areas. Rev Saude Publica, 44 (2010), pp. 1144–1149
Veras, Maria Amélia S.M. Brendan Flannery, José Cassio de Moraes, Antonia Maria da Silva Teixeira, Expedito J.A. Luna, Yellow fever vaccination coverage among children in Brazilian capitals, Vaccine, Volume 28, Issue 39, 7 September 2010, Pages 6478-6482
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