As the second stage of the epidemiological investigation to clarify the death that occurred in April, due to eosinophilic meningitis, in Nova Iguaçu, in Baixada Fluminense, researchers from the Oswaldo Cruz Institute (IOC/Fiocruz) returned to the location. This time, to collect and analyze rodents.
In the first stage of the work, experts had identified the presence of the worm Angiostrongylus cantonensis, which causes the disease, into one aquatic snail and two land snails.
However, an important assessment remained to be made to conclude the investigation of the case, since, to perpetuate itself in nature, the worm depends on two hosts: a mollusk and a rodent.
Researchers set traps to collect small mammals in the region where the case of eosinophilic meningitis occurred. Photo: Archive IOC
The cycle works as follows: the larvae eliminated by the mollusks (called L3) infect rodents, such as urban rats. In these hosts, they evolve until they reach the adult form of the worm, which reproduces, generating eggs, which hatch and release larvae (called L1).
L1 larvae are eliminated in rodent feces and ingested by snails. Inside the molluscs, they develop until they reach the L3 larval form, which is infective to rodents and can accidentally infect humans.
To unravel the complete cycle of the disease, researchers collected small mammals in the area where the case was recorded.
Fifteen animals were captured, including ten rats of the species Rattus norvegicus, three possums of the species Didelphis aurita and two cavies of the species Cavia fulgida.
Among these, worm infection cantonensis was confirmed in five mice R. norvegicus, popularly known as sewer rats.
Rat caught in an area with accumulated garbage. Photo: Archive IOC
The finding was conducted by the Laboratory of Biology and Parasitology of Wild Mammals Reservoirs of IOC, which acts at a reference level, together with the Ministry of Health, for taxonomy and diagnosis of wild animals that are reservoirs of diseases.
Scientists joined efforts initiated by the Malacology Laboratory of IOC/Fiocruz, who conducted the first stage of the investigation.
All results were communicated to the Municipal Health Department, which requested the investigation, and to the Ministry of Health, through a report.
Researchers from the Evandro Chagas National Institute of Infectology (INI/Fiocruz) and the Federal Rural University of Rio de Janeiro (UFRRJ) participated in the second stage of the work.
The partnership with technicians from the Superintendence of Environmental Health Surveillance of Nova Iguaçu (Suvam/Nova Iguaçu) was fundamental in all stages of the investigation.
Detection of the worm in snails and rats confirms that the complete cycle of disease transmission is established in the region where the patient was infected.
“We found a high rate of infectivity in rats, which were captured in just three nights of collection, inside and in the backyards of homes. This shows that the parasite is circulating in the environment and represents a risk to the population,” says Paulo D'Andrea, coordinator of the National Reference Laboratory for Taxonomy and Diagnosis of Wild Leishmaniasis Reservoirs.
Considering the findings, the researchers point out the need for control measures for both hosts of the parasite.
“In the short term, actions can be taken to reduce the rodent population. In the medium and long term, it is important to regulate the collection of organic waste and implement sewage systems in the region, because accumulated waste and open sewage attract rats to homes,” says Michele dos Santos, deputy coordinator of the National Reference Laboratory for Taxonomy and Diagnosis of Wild Leishmaniasis Reservoirs.
Open sewage in the region where the incident occurred contributes to attracting rats to homes. Photo: Archive IOC
Regarding snails, experts indicate that manual collection is the main strategy to combat the giant African snail (species Achatina fulica), which is involved in most cases of eosinophilic meningitis.
It is important to carry out the procedure with your hands protected by gloves or plastic bags to avoid contamination. Check out the step-by-step instructions here.
In addition to controlling hosts, researchers reinforce the importance of informing and guiding the population to prevent new cases of worm infection, through health education actions for different audiences.
People can become infected with the meningitis worm by eating undercooked infected snails or consuming poorly cleaned foods contaminated by the mucus excreted by the mollusks, such as vegetables, fruits and legumes.
The main precautions to avoid infection include:
Do not eat raw or undercooked shellfish, including land or water snails and slugs;
Wash fruits and vegetables well, leaving them to soak for 30 minutes in a mixture with a liter of water and a tablespoon of bleach, rinsing them well in running water before consumption.
“Avoiding the accumulation of trash and debris in homes helps reduce the presence of rats. Care must be taken when using rat poison due to the risk of accidental ingestion and poisoning, especially for children and other animals,” warns Michele.
Like other forms of meningitis, the infection causes inflammation of the meninges, the membranes that surround the central nervous system, including the brain and spinal cord.
Headache is the most common symptom of eosinophilic meningitis. Neck stiffness, fever, visual disturbances, nausea, vomiting, and persistent paresthesia (e.g., tingling or numbness) may also occur.
In most cases, the patient heals spontaneously. However, medical monitoring is important because some individuals develop serious conditions, which can lead to death.
Treatment seeks to reduce inflammation in the central nervous system and alleviate pain, in addition to preventing complications.
To identify the rodents involved in the worm cycle, researchers set traps in backyards and inside homes and commercial establishments near the place where the infection probably occurred.
Field laboratory was set up for initial analysis. Photo: Archive IOC
The initial analyses were carried out in the field laboratory, set up in the Ipiranga neighborhood, close to the area where the animals were captured, and later, in the laboratories of IOC.
The species of captured mammals and parasites were identified through morphological analysis (which studies the shape and structure of organisms) and, when necessary, genetic sequencing.
All procedures followed protocols established by the Laboratory of Biology and Parasitology of Wild Mammals of the Reservoirs of IOC, considering biosafety parameters and ethics in animal handling.
The first analyses carried out after the case detected the worm cantonensis in aquatic snails of the genus Pomacea, popularly known as lolô or aruá.
Subsequently, the infection was also confirmed in terrestrial molluscs of the species Achatina fulica, called giant African snail, which were collected by the Suvam/Nova Iguaçu team and analyzed by the Malacology Laboratory of IOC.
All findings were communicated through reports sent to the Municipal Health Department and the Ministry of Health.
As the second stage of the epidemiological investigation to clarify the death that occurred in April, due to eosinophilic meningitis, in Nova Iguaçu, in Baixada Fluminense, researchers from the Oswaldo Cruz Institute (IOC/Fiocruz) returned to the location. This time, to collect and analyze rodents.
In the first stage of the work, experts had identified the presence of the worm Angiostrongylus cantonensis, which causes the disease, into one aquatic snail and two land snails.
However, an important assessment remained to be made to conclude the investigation of the case, since, to perpetuate itself in nature, the worm depends on two hosts: a mollusk and a rodent.
Researchers set traps to collect small mammals in the region where the case of eosinophilic meningitis occurred. Photo: Archive IOC
The cycle works as follows: the larvae eliminated by the mollusks (called L3) infect rodents, such as urban rats. In these hosts, they evolve until they reach the adult form of the worm, which reproduces, generating eggs, which hatch and release larvae (called L1).
L1 larvae are eliminated in rodent feces and ingested by snails. Inside the molluscs, they develop until they reach the L3 larval form, which is infective to rodents and can accidentally infect humans.
To unravel the complete cycle of the disease, researchers collected small mammals in the area where the case was recorded.
Fifteen animals were captured, including ten rats of the species Rattus norvegicus, three possums of the species Didelphis aurita and two cavies of the species Cavia fulgida.
Among these, worm infection cantonensis was confirmed in five mice R. norvegicus, popularly known as sewer rats.
Rat caught in an area with accumulated garbage. Photo: Archive IOC
The finding was conducted by the Laboratory of Biology and Parasitology of Wild Mammals Reservoirs of IOC, which acts at a reference level, together with the Ministry of Health, for taxonomy and diagnosis of wild animals that are reservoirs of diseases.
Scientists joined efforts initiated by the Malacology Laboratory of IOC/Fiocruz, who conducted the first stage of the investigation.
All results were communicated to the Municipal Health Department, which requested the investigation, and to the Ministry of Health, through a report.
Researchers from the Evandro Chagas National Institute of Infectology (INI/Fiocruz) and the Federal Rural University of Rio de Janeiro (UFRRJ) participated in the second stage of the work.
The partnership with technicians from the Superintendence of Environmental Health Surveillance of Nova Iguaçu (Suvam/Nova Iguaçu) was fundamental in all stages of the investigation.
Detection of the worm in snails and rats confirms that the complete cycle of disease transmission is established in the region where the patient was infected.
“We found a high rate of infectivity in rats, which were captured in just three nights of collection, inside and in the backyards of homes. This shows that the parasite is circulating in the environment and represents a risk to the population,” says Paulo D'Andrea, coordinator of the National Reference Laboratory for Taxonomy and Diagnosis of Wild Leishmaniasis Reservoirs.
Considering the findings, the researchers point out the need for control measures for both hosts of the parasite.
“In the short term, actions can be taken to reduce the rodent population. In the medium and long term, it is important to regulate the collection of organic waste and implement sewage systems in the region, because accumulated waste and open sewage attract rats to homes,” says Michele dos Santos, deputy coordinator of the National Reference Laboratory for Taxonomy and Diagnosis of Wild Leishmaniasis Reservoirs.
Open sewage in the region where the incident occurred contributes to attracting rats to homes. Photo: Archive IOC
Regarding snails, experts indicate that manual collection is the main strategy to combat the giant African snail (species Achatina fulica), which is involved in most cases of eosinophilic meningitis.
It is important to carry out the procedure with your hands protected by gloves or plastic bags to avoid contamination. Check out the step-by-step instructions here.
In addition to controlling hosts, researchers reinforce the importance of informing and guiding the population to prevent new cases of worm infection, through health education actions for different audiences.
People can become infected with the meningitis worm by eating undercooked infected snails or consuming poorly cleaned foods contaminated by the mucus excreted by the mollusks, such as vegetables, fruits and legumes.
The main precautions to avoid infection include:
Do not eat raw or undercooked shellfish, including land or water snails and slugs;
Wash fruits and vegetables well, leaving them to soak for 30 minutes in a mixture with a liter of water and a tablespoon of bleach, rinsing them well in running water before consumption.
“Avoiding the accumulation of trash and debris in homes helps reduce the presence of rats. Care must be taken when using rat poison due to the risk of accidental ingestion and poisoning, especially for children and other animals,” warns Michele.
Like other forms of meningitis, the infection causes inflammation of the meninges, the membranes that surround the central nervous system, including the brain and spinal cord.
Headache is the most common symptom of eosinophilic meningitis. Neck stiffness, fever, visual disturbances, nausea, vomiting, and persistent paresthesia (e.g., tingling or numbness) may also occur.
In most cases, the patient heals spontaneously. However, medical monitoring is important because some individuals develop serious conditions, which can lead to death.
Treatment seeks to reduce inflammation in the central nervous system and alleviate pain, in addition to preventing complications.
To identify the rodents involved in the worm cycle, researchers set traps in backyards and inside homes and commercial establishments near the place where the infection probably occurred.
Field laboratory was set up for initial analysis. Photo: Archive IOC
The initial analyses were carried out in the field laboratory, set up in the Ipiranga neighborhood, close to the area where the animals were captured, and later, in the laboratories of IOC.
The species of captured mammals and parasites were identified through morphological analysis (which studies the shape and structure of organisms) and, when necessary, genetic sequencing.
All procedures followed protocols established by the Laboratory of Biology and Parasitology of Wild Mammals of the Reservoirs of IOC, considering biosafety parameters and ethics in animal handling.
The first analyses carried out after the case detected the worm cantonensis in aquatic snails of the genus Pomacea, popularly known as lolô or aruá.
Subsequently, the infection was also confirmed in terrestrial molluscs of the species Achatina fulica, called giant African snail, which were collected by the Suvam/Nova Iguaçu team and analyzed by the Malacology Laboratory of IOC.
All findings were communicated through reports sent to the Municipal Health Department and the Ministry of Health.
The non-profit reproduction of the text is allowed as long as the source is cited (Comunicação / Instituto Oswaldo Cruz)
 |
 |
