HEALTH-BRAZIL: The Jungle’s Lethal Secrets

By Mario Osava Reprint | | Print |

Mario Osava

RIO DE JANEIRO, Apr 30 2001 (IPS) - Recent outbreaks of yellow fever in Brazil serve as a reminder that jungles are home to microorganisms that can be dangerous to human health, meaning ecological tourism, wild animal smuggling, and the advance of economic activities in the Amazon may contribute to the spread of lethal diseases.

Dener Giovanini, coordinator of the National Network to Fight Wild Animal Trafficking (RENCTAS), a Brazilian non-governmental organisation, is sounding the alarm.

The Ebola virus, which was first documented in 1976 in the Democratic Republic of the Congo and in Sudan, is one well-known example of risks humans face as we increasingly come into contact with the wilds. Ebola is a deadly haemorrhagic fever, the latest outbreak of which occurred in Uganda in August 2000 and was not contained until January of this year.

There are also equally mysterious but lesser known diseases, such as the Marburg virus, identified in 1967 among laboratory workers in Marburg, Germany, and in Belgrade who had been exposed to blood and tissue of monkeys imported from Uganda’s jungles, Giovanini told IPS.

He mentioned Legionnaire’s disease (Legionella pneumophila) as another example, explaining that it is caused by bacteria that can survive under a broad spectrum of physio-chemical conditions. Its name comes from the fact that it was first identified at a convention of the American Legion in 1976, in the US city of Philadelphia.

In Brazil there are frequent reports of deaths in which the cause is listed simply as “haemorrhagic fever” of unknown origins, but the necessary monitoring does not occur, nor are preventive measures established that could prevent potential tragedy, lamented Giovanini.

Among the diseases originating in the jungles, sylvatic yellow fever stands out, and is now threatening to return to the cities of Brazil, after being eradicated from urban areas 60 years ago.

A rash of yellow fever cases occurred 100 km from Belo Horizonte, a city in south-central Brazil, killing 18 of the 40 people infected from late January to early April this year, according to the Health Department of Minas Gerais state.

All had contracted the disease, caused by the ‘Charon evegatus’ virus, through mosquito bites. The insects had previously bitten monkeys carrying the virus, thus transmitting it to humans. The symptoms include fever, haemorrhage and yellow-toned skin colour.

The mortality rate of this strain of yellow fever is high, reaching 71 percent in Brazil in the past three years.

The small, dark-coloured ‘Aedes aegypti’ mosquito serves as the vector for both yellow fever and dengue fever, the latter of which has established a presence in several Brazilian cities, further underscoring the threat of urban epidemics.

Health authorities stress that it is essential to combat the ‘Aedes aegypti’ mosquito, which became endemic in the country 15 years ago, because it has caused dengue epidemics in 20 of Brazil’s 26 states. The situation has been even worse this year, with an increase in the number of cases and the more lethal haemorrhagic dengue fever appearing in several cities.

The victims of the recent yellow fever outbreaks recorded in several municipalities west of Belo Horizonte were local residents and tourists. Some 60,000 people visited the region during the Carnival holidays in late February, most to make fishing excursions in the rivers – where the disease-carrying mosquitoes abound.

At least two of the victims lived in the Belo Horizonte metropolitan area, home to around four million people. Health authorities launched a vaccination campaign there in February and are confident that they prevented the risk of new cases in the cities.

The yellow fever virus is endemic in the Amazon and is now going through a cycle of expansion toward the centre of the country, stated Rogerio Valls, a specialist at the Evandro Chagas Hospital in Rio de Janeiro.

The disease was identified in the third victim, “then everyone ran to get vaccinated,” reported María do Rosario Bento, a nurse living in Leandro Ferreira, a small town in which there were four deaths from yellow fever.

Also found in Minas Gerais state is maculous fever, another rural plague. The transmission agent is the tick, and the disease causes haemorrhaging followed by death within a week, says Mariana Gontijo de Brito, an expert at the state Health Department.

Five people died last year from maculous fever in a city surrounded by cattle ranches, said Gontijo de Brito, a veterinarian specialising in zoonosis, that is, animal diseases that can be transmitted to humans.

The Amazon jungles represent an enormous repository of microorganisms that are still unknown – and potentially lethal to human beings.

The Oswaldo Cruz Foundation, a Rio de Janeiro-based epidemiological research institute, has set up a “virus hunting” laboratory in the Amazon to identify the microorganisms and produce vaccines before diseases can spread, said Luciano Toledo, head of the scientific outpost.

An officer at a military compound near Manaos, capital of Amazonas state, died four years ago from an unidentified virus after eating monkey meat. The two soldiers who shared the meal with him became seriously ill, but survived.

Since then, the army has maintained a ban prohibiting troops from consuming monkey.

The indigenous peoples of the Amazon are naturally immune to yellow fever, and the urban populations in the region are mostly vaccinated, Toledo explained. Vaccination is essential for visitors, though there are cases in which foreign tourists have returned ill to their home countries and died because they were uninformed of the disease.

Viruses carried by eco-tourists or by animals smuggled abroad could later mutate into a more dangerous or untreatable disease, Giovanini pointed out. In that respect, he said, scientists have not ruled out the hypothesis that this was the trajectory of the human immuno-deficiency virus (HIV), the precursor to AIDS.