Clinical Updates
29 January 2009
Yellow fever – Global situation
Yellow fever is a serious viral disease affecting non-human primates and humans in the tropical regions of the Americas and sub-Saharan Africa. Details of the risk of yellow fever in specific countries can be found on the NaTHNaC Country Information Pages.
This update details outbreaks of yellow fever reported since the last NaTHNaC update of 1 August 2008 [1]. The number of cases reported annually to the World Health Organization (WHO) can be found on the WHO website.
The Americas
Argentina: Following previously reported human cases in Misiones Province in early 2008 [1], in January 2009 two cases in humans were reported from Misiones Province with the probable infection site in the area of Fachinal, Misiones [2].
In October 2008, cases were reported in non-human primates in Guaraní, Misiones [3]. Since November 2008, cases in non-human primates have been reported from three areas of Misiones, and seven areas of Corrientes Province, although only one outbreak has been laboratory confirmed [2]. Surveillance activities regarding monkey deaths are being carried out.
Brazil: In November 2008, the Brazilian Ministry of Health released a map of areas for which they now advise yellow fever vaccination. See the NaTHNaC Clinical Update on yellow fever vaccination recommendations for more information.
Following cases of yellow fever in humans in early 2008 [1], six suspected cases of yellow fever were reported in humans in Rio Grande do Sul between 10 December 2008 and 16 January 2009 [4]. Two of the cases have been confirmed, yellow fever has been ruled out in one case and the other three cases are being investigated. One of the confirmed cases is thought to have been infected in the city of Pirapó, and the place of infection of the other confirmed case is still under investigation. A vaccination campaign is underway in the state.
Between October 2008 and 15 January 2009, probable or confirmed cases of yellow fever in non-human primates were reported from 23 cities in the state of Rio Grande do Sul.
Colombia: In December 2008 and January 2009, two cases of yellow fever in humans were reported in the department of Meta [2].
Trinidad and Tobago: In January 2009, dead monkeys were found in Trinidad. Yellow fever has been confirmed in two of these monkeys [2, 5]. The confirmed cases were in the districts of Mayaro and Nariva. These are the first cases in monkeys reported since 1995.
Africa
Burkina Faso: On 3 November 2008, two confirmed cases of yellow fever were reported in Ouahigouya, Yatenga [6]. The initial case was a seven month old boy who recovered and the second case was a six year old boy who died. Neither case had been vaccinated against yellow fever. A vaccination campaign was initiated in response to the outbreak.
Central African Republic: On 22 August 2008, a case of yellow fever was reported in a 32 year old man from Ngotto village, sub-prefecture of Boda, Prefecture of La Lobaye [7]. A further four individuals were identified who had symptoms of fever or jaundice. A vaccination campaign was initiated in La Lobaye in response to the outbreak.
Côte d’Ivoire: Five confirmed cases of yellow fever were reported between May and August 2008 [8]. The first case was in a 48 year old woman from Cocody, Abidjan who was vaccinated in 1997 and the second was in a 20 year old man from Treichville, Abidjan who had never been vaccinated. No details are available on the other three cases. A further four suspected cases were also reported. A mass vaccination campaign was conducted in Abidjan in August 2008 in response to the outbreak.
Guinea: A confirmed case of yellow fever was reported in Bounouma in Loma on 20 August 2008, and a further case was reported on 12 September 2008 in N'zérékoré [9]. Neither case had a history of yellow fever vaccination. Following investigation by a Ministry of Health and WHO investigation team, a further 14 suspected cases were identified retrospectively, one of which was fatal.
On 31 December 2008, two confirmed cases were reported in Faranah, with onset of symptoms for both cases in November 2008 [10]. A further 21 clinical suspected yellow fever cases were reported, of which three were fatal. A reactive vaccination campaign has been planned in Faranah.
Sierra Leone: Two confirmed cases of yellow fever were reported on 12 December 2008, one from Gerihun and one from Jembe, both in Bo district [11]. The initial case had onset of symptoms on 7 October, and the second case had onset of symptoms on 13 November 2008. A further seven suspected cases were reported, with no deaths. A reactive vaccination campaign is being conducted in Bo.
Advice for travellers
Yellow fever is transmitted to non-human primates or humans via the bite of an infected mosquito. In South America, the virus is transmitted via the bite of Aedes spp. mosquitoes (urban transmission from human to mosquito to human) or Haemogogus spp. (jungle transmission from monkey to mosquito to human) and Aedes spp mosquito in Africa. These mosquitoes feed predominantly during daylight hours. Travellers should take mosquito bite avoidance measures.
Full details of yellow fever vaccination recommendations can be found on the NaTHNaC Country Information Pages. Some countries require proof of yellow fever vaccination under the International Health Regulations (2005). Details of these requirements can also be found on the Country Information Pages.
References
1. NaTHNaC. Yellow fever outbreaks and current recommendations – update, 1 August 2008. Accessed 23 January 2009. Available at: http://www.nathnac.org/pro/clinical_updates/yf_010808.htm
2. Pan American Health Organization. Epidemiological Alert: Increase in circulation of yellow fever virus in the Americas, 27 January 2009. Accessed 28 January 2009. Available at: http://devserver.paho.org/hq/index.php?option=com_content&tas
3. Pan American Health Organization. Emerging and Reemerging Infectious Diseases, 13 November 2008. Accessed 23 January 2009. Available at: http://www.paho.org/English/AD/DPC/CD/eid-eer-2008-11-13.htm
4. Governo do Esado Rio Grande do Sul. Saúde divulga esclarecimento técnico sobre a febre amerela, 16 January 2009. Accessed 23 January 2009. Available at: http://www.estado.rs.gov.br/direciona.php?key=aW50PW5vdGlja
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5. Ministry of Health, Trinidad and Tobago. Update on Dead Monkeys found in the Forest, 19 January 2009. Accessed 23 January 2009. Available at: http://www.health.gov.tt/applicationloader.asp?app=newsarticles
6. World Health Organization. Yellow fever in Burkina Faso, 3 November 2008. Accessed 23 January 2009. Available at: http://www.who.int/csr/don/2008_11_03/en/index.html
7. World Health Organization. Yellow fever in the Central African Republic, 30 October 2008. Accessed 23 January 2009. Available at: http://www.who.int/csr/don/2008_10_30/en/index.html
8. World Health Organization. Yellow fever in the Côte d’Ivoire, 8 August 2008. Accessed 23 January 2009. Available at: http://www.who.int/csr/don/2008_08_08/en/index.html
9. World Health Organization. Yellow fever in Guinea, 29 September 2008. Accessed 23 January 2009. Available at: http://www.who.int/csr/don/2008_09_29/en/index.html
10. World Health Organization. Yellow fever in Guinea, 14 January 2009. Accessed 23 January 2009. Available at: http://www.who.int/csr/don/2009_01_14/en/index.html
11. World Health Organization. Yellow fever in Sierra Leone, 6 January 2009. Accessed 23 January 2009. Available at: http://www.who.int/csr/don/2009_01_06a/en/index.html
Links
NaTHNaC Health Information Sheet on yellow fever
NaTHNaC Health Information Sheet on insect bite avoidance
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