The afternoon is hot and sticky on the banks of the Napo River, an arm of the Amazon, but Claudio, a logger, is shivering in his creaky wooden bed.
“I feel bad, very bad, pain all over my body, fever, high fever, shudders," he says. "I have malaria; this is the 17th time so far. I don’t know what to do any more."
The mosquito-borne illness has returned to the many villages only accessible by boat in the Peruvian Amazon, inflicting on the inhabitants days of fever, permanent anaemia and — in the worst cases — death.
In Peru, malaria was almost eradicated 40 years ago, but this year 64,000 cases have been registered in the country, half in the Amazon region. It is thought there are many more unregistered cases deep within the massive and humid rainforest, where health authorities find it almost impossible to gain access.
"Malaria is present. There have been 32,000 cases this year in this area alone — that says malaria is very much present," said Hugo Rodríguez, a doctor at the Andean Health Organisation, which is fighting malaria in border areas of Peru, Ecuador, Colombia and Venezuela.
His organisation distributes mosquito nets to some villagers, spreading the message through the area that the illness is dangerous and — where it can identify the cases — helping in post-infection treatment.
"Now we are not talking about eradicating malaria any more, as that is impossible and unsustainable; we are doing our best to try and control it," he added.
Climate change and deforestation are behind the return of malaria in the Peruvian Amazon.
Off-season rain is altering the pattern of mosquito development, leaving puddles containing the lethal larvae in areas where malaria had been nonexistent.
"The actual malaria problem of the Peruvian Amazon is caused by constant climate changes," said biologist Carlos Pacheco, head of the mosquito control unit in Iquitos, the regional capital.
And deforestation is having a similar effect, forcing the mosquito to move to new areas and spreading the disease to places where people are not aware of the disease, where villagers lack the means to get hold of mosquito nets and preventive medicines, and where health authorities have no presence.
"Every time we fight the mosquito, we feel we are fighting against a much more evolved and adaptable one, one that can easily migrate to areas that were clean of malaria before and that are very hard to access," said Pacheco.
Two scientific reports last year linked malaria with deforestation. Peruvian researchers found that frontier areas cleared of trees for logging, settlements, roads, farming or mining were far more likely to harbour malaria-carrying mosquitoes.
In one Peruvian study, researchers said the biting rate of mosquitoes in deforested areas was nearly 300 times greater than in virgin forests. Increases in human population density had no impact on biting rates.
The insects lay their eggs and thrive in open, sunlit pools of water. Road builders dig channels and culverts which become blocked; silt washes off farmland, blocking streams; and opencast mines and new settlements create ideal breeding grounds.
Anyone who catches malaria in the Amazon region has few opportunities for treatment. Even in the most densely populated areas, there are few health centres.
Loggers are the mosquitoes’ main victim. "The districts with the higher logging activity are the critical ones, making the disease there to be almost impossible to control," said Rodríguez. "It is very hard to access the areas where the clearing of the rainforest occurs and these people are not conscious of the risks and once infected — and sometimes because of the illegality of this activity — loggers are very reluctant to get treated by health authorities."
Alongside the Amazon River and its many tributaries, poverty-stricken loggers like Claudio move deep into the rainforest, in areas where malaria is prevalent, without taking any precautions, and for meagre wages.
Pointing at his neighbour’s one-year-old son who is recovering from the disease, Arquímedes of the village of Manacamiri near Iquitos said: "Here most people suffer from this disease, from malaria.There are no other diseases like this, no other problems like this here … We have now become the malaria zone."
Behind him, the bank of the low Nanay River seems nothing more than a mud puddle with mosquitoes buzzing around. “Children, elderly — how many deaths we already had," said Arquímedes.
"At the beginning we had no idea what it was, and it was malaria … there is not a single day without a malaria patient."
Copyright Guardian News & Media Ltd 2007