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Published Date: 2019-02-11 18:36:12
Subject: PRO/AH/EDR> Yellow fever - Americas (03): Brazil (PR, SP)
Archive Number: 20190211.6310963
YELLOW FEVER - AMERICAS (03): BRAZIL (PARANA, SAO PAULO)
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Date: Mon 11 Feb 2019
Source: WHO Emergencies preparedness, response [edited]
https://www.who.int/csr/don/11-february-2019-yellow-fever-brazil/en/


Brazil is currently in the seasonal period for yellow fever, which occurs from December through May. The expansion of the historical area of yellow fever transmission to areas in the south-east of the country in areas along the Atlantic coast previously considered risk-free led to 2 waves of transmission (Figure 1), one during the 2016-2017 seasonal period, with 778 human cases, including 262 deaths, and another during the 2017-2018 seasonal period, with 1376 human cases, including 483 deaths.

From December 2018 through January 2019, 361 confirmed human cases, including 8 deaths, have been reported in 11 municipalities of 2 states of Brazil. In the southern part of Sao Paulo state, 7 municipalities: El dorado (16 cases), Jacupiranga (1 case), Iporanga (7 cases), Cananeia (3 cases), Cajati (2), Pariquera-Açu (1), and Sete Barras (1) reported confirmed cases. In the same state, additional cases in Vargem (1) and Serra Negra (1) municipalities were confirmed on the border with Minas Gerais state. Additionally, 2 cases have been confirmed in the municipalities of Antonina and Adrianopolis, located in the eastern part of Parana state. These are the 1st confirmed yellow fever cases reported since 2015 from Parana, a populous state with an international border. Among these confirmed cases, 89% (32/36) are male, the median age is 43 years, and at least 64% (23/36) are rural workers.

Human cases reported so far during the current 2018-2019 period (July 2018 to Jan 2019) in 9 municipalities in Sao Paulo state, as well as the confirmation of human cases and epizootic due to yellow fever in the state of Parana, mark the beginning of what could be a 3rd wave and a progression of the outbreak towards the Southeast and South regions of the country (Figure 2). While too early to determine whether this year [2019] will show the high numbers of human cases observed in the last 2 large seasonal peaks, there is indication that the virus transmission is continuing to spread in a southerly direction and in areas with low population immunity.

Figure 1 [graph]. Distribution of confirmed human yellow fever cases by date of onset of symptoms in Brazil from 2016-2019.
Figure 2 [maps]. Distribution of epizootics and confirmed human cases in Brazil from 1 Jan 2016 through 26 Jan 2019.

Surveillance of non-human primate (NHP) epizootics:
From 1 Jul 2018 through 18 Jan 2019, 25 confirmed epizootics were reported in 5 federal entities: Sao Paulo (13), Rio de Janeiro (8), Minas Gerais (1), Mato Grosso (2) and Parana (1). In the last 4 weeks, epizootics have been confirmed in Sao Paulo and Parana states. Additionally, the Parana Secretariat of Health reported that tests performed on dead monkeys in Antonina, on the Parana coast were positive for yellow fever. Given the gradual geographical expansion of the epizootic wave that Brazil has faced during the last 2 seasonal periods, the country has had to adapt its immunization policies for yellow fever. The number of areas with recommended vaccination has increased from 3526 municipalities in 2010 to 4469 (out of 55 702) municipalities in 2018. In line with the World Health Organization guidelines, Brazil has adopted a single dose vaccination scheme for yellow fever since April 2017.

During the 2017-2018 season, Brazil adopted the use of fractional dose yellow fever vaccination to respond to outbreaks and the risk of urbanization of yellow fever, especially in large cities. This strategy was implemented in 77 municipalities with the greatest risk for yellow fever in the states of Sao Paulo (54 municipalities), Rio de Janeiro (15 municipalities), and Bahia (8 municipalities).

As of 29 Sep 2018, preliminary results of the mass vaccination campaign against yellow fever indicate that 13.3 million people in Sao Paulo, 6.5 million in Rio de Janeiro, and 1.85 million in Bahia states were vaccinated, which represents vaccination coverage of 53.6%, 55.6% and 55.0%, respectively.

Furthermore, data from the Brazil Ministry of Health indicate that vaccination coverage of 95% and greater has been reached in 13% (57/435) of municipalities considered to be at-risk in Parana, 21% (113/531) of municipalities at-risk in Rio Grande do Sul, 19% (155/838) of municipalities at-risk in Sao Paulo, and 9% (38/428) of municipalities at-risk in Santa Catarina.

Brazil has recommended additional supplementary vaccination of approximately 3 million persons in Sao Paulo State in urban areas in response to the current season, albeit not yet determined whether full or fractional dose. In January 2019, vaccinations also began in 36 Quilombo communities -- indigenous populations living in high risk environments for sylvatic transmission -- in Sao Paolo region, and close to 3300 people were vaccinated in Antonina municipality in Parana state. Additionally, the state and affected municipalities developed a task force who have targeted vaccination of 28 299 unvaccinated additional persons in coming days in the municipalities of Cajati, Iporanga, and Barra do Turvo.

Further transmission is expected in the coming months based on seasonal patterns. Recent human cases of yellow fever during the current seasonal cycle have been reported in Sao Paulo and Parana states in Southeast Brazil.

The preliminary results of vaccination coverages in municipalities from Parana, Rio Grande do Sul, Sao Paulo, and Santa Catarina states suggest that a high proportion of persons remain at-risk and that there is a necessity to intensify risk communications among high-risk groups.

The geographical distribution of human cases and epizootics from the current and previous 2 seasonal cycles suggests southward movement of the virus, which presents further risk to the states of Parana, Rio Grande do Sul, and Santa Catarina, as no epizootics or human cases were confirmed in recent years prior. Furthermore, these areas have ecosystems favorable for yellow fever transmission and border other countries such as Argentina, Paraguay, and Uruguay.

During the previous season cycle, human yellow fever cases were reported among travelers, though to date, most imported cases have been reported in countries where the vector is absent (or absent during winter). These reports illustrate the importance of maintaining high levels of awareness, especially for international travelers from areas with favorable ecosystems for yellow fever transmission.

To date, yellow fever transmission by _Aedes aegypti_ has not been documented, however the high incidence observed in the last 2 seasons may reflect the increased contact of sylvatic environments (vectors and non-human primates) and under-protected populations in urban or peri-urban settings. The sylvatic yellow fever virus is transmitted to monkeys by forest dwelling mosquitoes such as _Haemagogus_ and _Sabethes_ spp. Humans who are exposed to these mosquitoes can become infected if they are not vaccinated. In entomological studies conducted during the 2016-2017 outbreak in some of the affected states, isolated _Haemagogus_ mosquitoes were found to be positive for yellow fever, indicating predominantly sylvatic transmission. More recently, an investigation conducted by the Evandro Chagas Institute reported by the Brazil Ministry of Health revealed the detection of yellow fever virus in _Aedes albopictus_ mosquitoes captured in rural areas of 2 municipalities in Minas Gerais (Itueta and Alvarenga) in 2017. The significance of this finding requires further investigation. The last documented outbreak of urban yellow fever in Brazil was recorded in 1942.

WHO continues to monitor the epidemiological situation and review the risk assessment based on the latest available information. Currently, based on available information, WHO assesses the overall risk as high at the national level, moderate at the regional level, and low at the global level.

On 25 Jan 2019, PAHO/WHO alerted 4 Member States about the beginning of the seasonal period for yellow fever and, therefore, the highest risk of transmission to unvaccinated humans. Thus, PAHO/WHO advises Member States with areas at risk for yellow fever to continue efforts to immunize the at-risk populations and to take the necessary actions to keep travelers informed and vaccinated prior to traveling to areas where yellow fever vaccination is recommended.

WHO recommends vaccination of international travellers above 9 months of age going to Brazil. The updated areas at-risk for yellow fever transmission and the related recommendations for vaccination of international travellers were updated by WHO on 3 May 2018; the map of revised areas at risk and yellow fever vaccination recommendations are available on the WHO International Travel and Health website.

Yellow fever can easily be prevented through immunization, provided that vaccination is administered at least 10 days before travel. Yellow fever vaccination is safe, highly effective and provides life-long protection. In accordance with the IHR (2005), the validity of the international certificate of vaccination against yellow fever extends to the life of the person vaccinated. A booster dose of yellow fever vaccine cannot be required of international travellers as a condition of entry.

Awareness of the signs and symptoms of yellow fever are recommended for anyone living or traveling in areas at risk for yellow fever transmission. Persons experiencing symptoms are encouraged to seek healthcare quickly.

WHO recommends against the application of any general travel or trade restrictions to Brazil based on the information available for this event.

--
Communicated by:
ProMED-mail
<promed@promedmail.org>

[The increasing number of yellow fever (YF) cases is a clear indication that the new, annual transmission season has begun. The non-human primate cases are indicative that the sylvan (forest) transmission cycle is again active, and spill-over to non-vaccinated humans will likely continue. The 2017-2018 YF cycle elicited active vaccination campaigns in the affected areas. With just under 54% of the Sao Paulo state population vaccinated, the campaign needs to continue. The risk, as mentioned above, is that the virus could be introduced into the urban and suburban setting where _Aedes aegypti_ vector populations are abundant with rapid spread in a largely susceptible human population. - Mod.TY

Maps of Brazil:
https://www.mapsland.com/maps/south-america/brazil/large-brazil-regions-map.jpg;

HealthMaps:
Brazil: http://healthmap.org/promed/p/6
Parana, Brazil: http://healthmap.org/promed/p/3985
Sao Paulo, Brazil: http://healthmap.org/promed/p/57793]

See Also

Yellow fever - Americas (02): Brazil (PR, SP) 20190208.6305966
Yellow fever - Americas: PAHO/WHO 20190129.6284631
2018
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Yellow fever - Americas (35): Brazil 20180828.5991288
Yellow fever - Americas (33): Brazil, monkeys 20180705.5890194
Yellow fever - Americas (32): Brazil (MT) 20180627.5880041
Yellow fever - Americas (31): Brazil 20180511.5792117
Yellow fever - Americas (30): Brazil 20180506.5786329
Yellow fever - Americas (29): Brazil 20180430.5774384
Yellow fever - Americas (28): Brazil 20180422.5761942
Yellow fever - Americas (27): Brazil 20180415.5747516
Yellow fever - Americas (26): Brazil (SP) 20180405.5727827
Yellow fever - Americas (25): Brazil 20180329.5716763
Yellow fever - Americas (24): Germany ex Brazil (RJ) 20180327.5714395
Yellow fever - Americas (23): Brazil 20180325.5708856
Yellow fever - Americas (22): South America 20180321.5699760
Yellow fever - Americas (20): Brazil 20180308.5674952
Yellow fever - Americas (19): Brazil 20180304.5662410
Yellow fever - Americas (18): WHO Brazil, Europe ex Brazil 20180301.5657769
Yellow fever - Americas (17): Europe, Argentina ex Brazil 20180228.5655137
Yellow fever - Americas (16): Brazil 20180224.5645739
Yellow fever - Americas (15): Brazil (RJ) 20180222.5643503
Yellow fever - Americas (14): PAHO/WHO 20180217.5634899
Yellow fever - Americas (13): Brazil 20180217.5634865
Yellow fever - Americas (12): Brazil monkeys 20180211.5622003
Yellow fever - Americas (11): Brazil monkeys 20180208.5613594
Yellow fever - Americas (10): Brazil 20180131.5597486
Yellow fever - Americas (09): Brazil, monkeys 20180129.5593289
Yellow fever - Americas (08): Brazil 20180127.5589055
Yellow fever - Americas (07): Brazil vaccination PAHO/WHO 20180126.5585612
Yellow fever - Americas (06): Brazil (SP) 20180124.5582416
Yellow fever - Americas (05): Brazil, WHO 20180124.5579973
Yellow fever - Americas (04): PAHO/WHO Brazil 20180117.5566554
Yellow fever - Americas (03): Brazil (SP) 20180117.5564150
Yellow fever - Netherlands: ex Brazil (SP) 20180115.5561671
Yellow fever - Americas (02): Brazil vaccination 20180112.5553721
Yellow fever - Americas: Brazil (SP) 20180109.5546267
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