Scientists still cannot identify the toxin after nearly a century
Nas últimas semanas de agosto, moradores de seis municípios amazônicos começaram a apresentar sintomas de uma doença rara que dissolve fibras musculares e escurece a urina — um mal conhecido desde 1924, mas cujo agente causador permanece um mistério para a ciência. A doença de Haff, associada ao consumo de peixes e crustáceos, lembra à humanidade que o oceano de desconhecido ainda é vasto, mesmo diante de quase um século de investigação. Com 44 casos suspeitos, uma morte e comunidades que dependem do peixe como alimento essencial, as autoridades brasileiras enfrentam não apenas um surto, mas a persistente opacidade da natureza.
- Desde 22 de agosto, 44 pessoas em seis municípios do Amazonas desenvolveram rabdomiólise — destruição de fibras musculares que pode levar à insuficiência renal e à morte.
- Itacoatiara concentra o epicentro do surto: 34 dos 44 casos e a única morte registrada, com dez pacientes ainda hospitalizados no fim de agosto.
- A doença de Haff desafia médicos há quase cem anos — a toxina não tem cheiro, cor nem sabor, resiste ao cozimento e ainda não foi identificada em laboratório.
- Autoridades pedem que qualquer pessoa com dor muscular intensa e urina escura após consumir peixe busque atendimento hospitalar em até 24 horas.
- O peixe é base da alimentação amazônica, e as autoridades equilibram o alerta sanitário com a necessidade de não gerar pânico em populações que dependem desse alimento para sobreviver.
No fim de agosto, agentes de saúde do Amazonas voltaram os olhos para Itacoatiara, cidade a 176 quilômetros de Manaus, onde dezenas de moradores começaram a sentir dores musculares intensas e a notar que sua urina havia escurecido de forma alarmante. Em poucos dias, o quadro se expandiu para mais cinco municípios — Silves, Manaus, Parintins, Caapiranga e Autazes —, totalizando 44 casos suspeitos de doença de Haff, condição popularmente chamada de "doença da urina preta".
A doença não é nova. Seus primeiros registros datam de 1924, nas margens do Mar de Königsberg, no Báltico. Desde então, surtos foram documentados na Suécia, na União Soviética, nos Estados Unidos, na China e no Brasil — onde os casos mais graves ocorreram em 2017, na Bahia. O que une todos esses episódios é o consumo de peixes ou crustáceos contaminados por uma toxina ainda desconhecida, que não deixa rastro sensorial e sobrevive ao calor do cozimento.
Os sintomas surgem em horas: dor muscular nos ombros, pescoço e trapézio, seguida por fraqueza, náusea e a característica urina cor de café, causada pela mioglobina liberada na destruição das células musculares. Essa proteína é tóxica para os rins, podendo levar à insuficiência renal e à necessidade de diálise. O tratamento baseia-se em hidratação intensa para proteger os rins e na suspensão de medicamentos que possam agravar o quadro.
Em Itacoatiara, uma pessoa morreu e dez seguiam hospitalizadas até 30 de agosto. As autoridades ainda não confirmaram oficialmente o diagnóstico de doença de Haff, pois a rabdomiólise pode ter outras causas. Especialistas da Fundação de Medicina Tropical de Manaus apontam que o quadro clínico sugere intoxicação alimentar, mas nenhuma análise laboratorial identificou o agente responsável até o momento.
Enquanto a investigação avança entre hipóteses de bactérias, vírus ou toxinas, as autoridades pedem calma — lembrando que o número de casos é pequeno diante do volume de peixe consumido na região — mas reforçam o alerta: qualquer sintoma deve ser levado a um hospital em até 24 horas. A Amazônia espera respostas que a ciência ainda não conseguiu dar em quase cem anos.
In the last days of August, health officials in the Brazilian Amazon turned their attention to Itacoatiara, a city 176 kilometers from Manaus. Starting on August 22, dozens of residents began showing symptoms of rabdomyolysis—a breakdown of muscle fibers that leaves the body weakened and in pain. By month's end, authorities had identified 44 suspected cases across six municipalities: Itacoatiara, Silves, Manaus, Parintins, Caapiranga, and Autazes. The leading theory was that these people had contracted Haff disease, a rare illness known colloquially as "black urine disease" because of one of its most distinctive symptoms.
Haff disease is not new. The first documented cases appeared in 1924 near the Königsberg Haff, a coastal region by the Baltic Sea that is now part of Kaliningrad, Russia. Physicians there described patients with sudden muscle rigidity and dark urine. Over the following nine years, more cases emerged, mostly in summer and autumn, and they all shared one thing: the people had eaten fish. The pattern was clear enough that doctors concluded a toxin—not a bacterial infection or virus—was responsible. Since then, outbreaks have surfaced in Sweden, the Soviet Union, the United States, and China. Brazil first saw cases in 2008 and 2009, but the most severe outbreak occurred in 2017, when Bahia recorded 71 patients, 66 of them in Salvador.
What makes Haff disease so difficult to combat is that nearly a century after its discovery, scientists still do not know what toxin causes it. The poison appears in certain fish species—salmon, pacu, eels, and many others from both fresh and salt water—as well as in crustaceans like lobsters, crayfish, and shrimp. Researchers suspect changes in aquatic ecosystems, cyanobacterial toxins, or heavy metals might be involved, but no toxic levels of these substances have been confirmed. The toxin leaves no trace: it has no smell, no taste, no color, and cooking does not destroy it.
The symptoms typically appear within hours of eating contaminated seafood. Muscle pain, especially in the shoulders, neck, and trapezius region, is the most common complaint. Some patients also experience chest pain, shortness of breath, numbness, nausea, dizziness, and weakness. The dark urine—resembling coffee in color—comes from myoglobin, an enzyme released when muscle cells break down and enter the bloodstream. This enzyme is toxic to the kidneys, which can lead to kidney failure and the need for dialysis in severe cases. Most people recover, but death is possible, particularly for those with existing health conditions.
Diagnosis can be made in a doctor's office by reviewing symptoms and confirming fish consumption in the previous 24 hours. Blood tests measuring enzymes like myoglobin and creatine phosphokinase provide definitive confirmation. Treatment centers on aggressive hydration to dilute impurities in the blood and reduce the burden on the kidneys. Doctors also stop prescribing medications that could further damage muscles and kidneys, such as statins and anti-inflammatory drugs. When kidney function deteriorates, dialysis becomes necessary.
In Itacoatiara, the hardest-hit city, 34 of the 44 cases were reported, along with one death. By August 30, ten people remained hospitalized, all from Itacoatiara; the rest had been discharged. Authorities have not officially confirmed that the outbreak is Haff disease, partly because rabdomyolysis can have other causes—trauma, intense exercise, seizures, certain medications, alcohol, heavy metals, or contaminated food. An infectologist from Manaus's Tropical Medicine Foundation noted that while the clinical picture suggests poisoning from food, and the rapid onset points to a toxin, no laboratory analysis has yet identified the actual cause.
Local health officials have urged calm, emphasizing that fish forms the foundation of the Amazonian diet and that the number of cases remains tiny compared to overall fish consumption. Yet they also stress the importance of seeking hospital care within 24 hours of symptom onset. The investigation continues, with authorities working through hypotheses—bacteria, virus, or toxin—while the people of the Amazon wait for answers that have eluded science for nearly a hundred years.
Notable Quotes
The disease causes muscle fiber destruction from an unknown toxin, and scientists have been trying to identify it since 1924 without success.— Dr. Luis Filipe Miranda, Nephrology Service, Hospital Português da Bahia
Fish forms the basis of the Amazonian diet, so the focus must be on rapid diagnosis and treatment rather than discouraging consumption.— Dr. Antonio Magela, Tropical Medicine Foundation, Manaus
The Hearth Conversation Another angle on the story
Why does a disease discovered in the 1920s near the Baltic Sea suddenly appear in the Amazon?
That's the question authorities are asking. Haff disease has surfaced sporadically in different parts of the world for decades. What's unusual here is the clustering—44 cases in a short window across six municipalities. It suggests something in the local fish supply, but we don't know what.
If cooking doesn't destroy the toxin, how are people supposed to protect themselves?
They can't, really. That's what makes this so difficult. There's no way to identify contaminated fish before eating it. The only real prevention is knowing the symptoms and getting to a hospital fast—within 24 hours.
What happens to someone's kidneys when this disease takes hold?
The muscle breakdown releases myoglobin into the blood, and that enzyme poisons the kidneys. In severe cases, the kidneys stop working entirely, and the person needs dialysis—sometimes for the rest of their life.
Has anyone figured out what the actual toxin is after all these years?
No. That's remarkable, really. Since 1924, researchers have been trying to identify it. They suspect it might be related to changes in the ecosystem, cyanobacteria, or heavy metals, but nothing has been confirmed. The toxin leaves no fingerprint.
What does it mean that fish is the foundation of the Amazon diet?
It means you can't tell people to stop eating fish. It's their primary protein source, their livelihood for many. So the authorities have to balance public health with economic and nutritional reality. They're asking people to be alert, not afraid.