HEALTH-BRAZIL: Urban Yellow Fever Threatens to Stage a Return

By Mario Osava Reprint | | Print |

Mario Osava

RIO DE JANEIRO, Mar 2 2001 (IPS) - Yellow fever, eliminated from urban areas in Brazil and limited to the Amazon jungle for more than half a century, has reappeared in a populated area in central Brazil, in an outbreak that has so far claimed 11 lives.

Local authorities have documented 22 cases in seven municipalities located 120 kms west of the capital of the state of Minas Gerais, Belo Horizonte, a city of nearly four million.

The panic is spreading in the area around the city due to the proliferation of the Aedes aegypti mosquito, a small, dark-colored mosquito that serves as the vector for both yellow fever and dengue fever.

This year, the dengue epidemic has flared up in several parts of Brazil, and in the state of Minas Gerais more than 2,000 cases have already been reported – which indicates the possibility that the virus that causes yellow fever could also spread.

Yellow fever is an acute destructive infectious disease of warm regions marked by sudden onset, prostration, fever, vomiting, damage to the liver and kidneys, albuminuria, jaundice and often hemorrhaging.

The disease is caused by the “Charon evegatus” virus, and the vaccine is produced with a live-attenuated virus strain.

The central government is worried about the new outbreak of urban yellow fever. Health Minister José Serra visited the affected region on Friday to assess the situation on the ground and discuss preventive measures with local authorities.

The fear of contagion has led people to flock to health clinics and hospitals to be vaccinated in Belo Horizonte, especially since at least 60,000 residents of that city travelled to the area where cases have been reported during the carnival holiday, last Saturday to Wednesday.

Minas Gerais Health Secretary Carlos Patricio de Freitas announced a mass vaccination campaign in the 37 municipalities making up the metropolitan region starting this weekend.

While De Freitas estimated that 70 percent of the 18 million inhabitants of Minas Gerais have already been vaccinated against the disease, the goal is to achieve 95 percent coverage.

Most Brazilians are only vaccinated against yellow fever before they make a trip to the Amazon jungle or some areas in west- central Brazil where sylvatic yellow fever, which is transmitted by another kind of mosquito, the Haemagogus, is endemic.

However, there are some areas of risk in Minas Gerais, which explains the fact that the rate of vaccination was high in the state even prior to this year’s outbreak, the first case of which was identified on Jan 23.

Authorities from other parts of Brazil, such as Rio de Janeiro Municipal Health Secretary Sergio Arouca, a respected public health expert, said an epidemic was not likely. He pointed out that the last outbreak of urban yellow fever occurred in 1942.

Only people who visit isolated, forested areas inhabited by infected monkeys and Haemagogus mosquitos come down with yellow fever these days, said Arouca, who ruled out the need for mass vaccination in Rio de Janeiro, which is located more than 500 kms from the area where the latest outbreak has been reported.

But the number of cases of sylvatic yellow fever documented by the Health Ministry is on the rise, from 38 in 1998 to 85 last year. The area of contagion is also expanding toward the southeast, the most populated, richest part of the country, which includes Minas Gerais, Rio de Janeiro and Sao Paulo.

Several tourists fell ill early last year after visiting Chapada de los Veadeiros, in the state of Goias, which borders Minas Gerais.

The mortality rate of yellow fever is high, amounting to 71 percent in Brazil in the past three years, which intensifies people’s fears.

The fact that so many cases have been reported in the centre of the state of Minas Gerais is even more alarming because they coincided with the epidemic of dengue fever, and have been reported in a populated area, which is not frequent, said Tania Marcial, an expert with the Minas Gerais Association of Infectious Diseases. She pointed out that the disease was usually seen in remote parts of northern and northeastern Brazil.

That makes it even more essential to combat the Aedes aegypti mosquito, which became endemic in the country 15 years ago, causing epidemics of dengue in 20 of Brazil’s 26 states. The situation has been even worse this year, due to the increase in the number of cases of the even more lethal hemorrhagic dengue fever in several cities.

Major epidemics of urban yellow fever broke out in Rio de Janeiro in the early 20th century. In 1902, the disease killed 984 people in what was then the capital of Brazil.

But a public health offensive led by Oswaldo Cruz, a hero of Brazilian medicine, got the disease under control in 1906.

Since no vaccine was yet available, Cruz resorted to strict health measures which included the demolition of many rundown homes, even entire neighbourhoods, which led to drastic changes in the city which at the time was home to just over 700,000 residents, but which now has a population eight times that.