Comparative single-cell #genomics of two uncultivated #Naegleria species harboring #Legionella #cobionts

 

ABSTRACT

Amoeboflagellates of the genus Naegleria are free-living protists ubiquitously found in soil and freshwater habitats worldwide. They include the “brain-eating amoeba” Naegleria fowleri, an opportunistic pathogen that causes primary amoebic meningoencephalitis, a rare but fatal infection of humans. Beyond their direct pathogenicity, protists can also act as environmental reservoirs for intracellular bacterial pathogens, such as Legionella spp., to persist and multiply in the environment. In this study, we carried out single-cell genome sequencing of two uncultivated Naegleria species isolated from the River Leam in England. From single cells, we generated two highly complete Naegleria genomes. Phylogenetic analyses placed these species as close relatives of Naegleria fultoni and Naegleria pagei. Exploring Naegleria evolutionary genomics, we identified gene families encoding antistasin-like domains, which have been characterized as factors that inhibit coagulation in blood-feeding leeches. Antistasin-like domains were identified in all sequenced Naegleria species and their close relative Willaertia magna, yet are otherwise largely restricted to animal genomes. Significantly, we recovered highly complete bacterial genomes from each Naegleria single-cell sample. Phylogenomic analysis revealed that both bacteria belong to the Legionellaceae family. Both bacterial genomes encode comprehensive sets of secretion systems and effector arsenals. We identified putative Legionella effectors that resemble TAL (Transcription activator-like) effectors from plant pathogenic Xanthomonas spp. in terms of protein sequence and predicted structure, representing a potentially novel class of Legionella effectors. Our study highlights the advantages of single-cell environmental genomics approaches, which enable direct association of intracellular pathogens with their hosts to better understand the evolution of host-pathogen interactions.

Source: mSphere, https://journals.asm.org/doi/full/10.1128/msphere.00352-25?af=R

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#USA, #Missouri: DHSS confirms #death of #patient with rare brain #infection {#Naegleria Fowleri}

Aug. 20 Update:  

In response to several media inquiries following up on this case, DHSS regrets to confirm that the patient's death occurred on Aug. 19 in a St. Louis area hospital. We extend our deepest condolences to the loved ones of the patient. 

Source: Department of Health, https://content.govdelivery.com/accounts/MODHSS/bulletins/3eebf32

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#USA, #Missouri Department of Health Confirmed a Case of Primary Amoebic #Meningoencephalitis {#PAM} (August 13 '25)

 

JEFFERSON CITY, MO – The Missouri Department of Health and Senior Services (DHSS) is announcing case of an adult Missouri resident with a laboratory-confirmed infection of Naegleria fowleri. 

Naegleria fowleri is a microscopic single-celled free-living ameba that can cause a rare deadly infection of the brain called primary amebic meningoencephalitis (PAM), also known as “brain-eating” infection. Typically, fewer than 10 people a year in the United States get PAM.

The Missouri patient is currently being treated for PAM in an intensive care unit of a hospital, and currently, no additional suspected cases of PAM are being investigated in Missouri.

The ameba is common and naturally present in warm freshwater such as lakes, rivers and ponds; however, PAM is extremely rare. Between 1962 and 2024, there were 167 reported cases of PAM in the United States.

The source of the patient’s exposure is currently being investigated by public health officials. 

While not confirmed, preliminary information implies the patient may have been water skiing at the Lake of the Ozarks days prior to becoming ill. 

Recreational water users should assume that Naegleria fowleri is present in warm freshwater across the United States; however, infection remains very rare.

Although a rare occurrence, people become infected by Naegleria fowleri when water containing the ameba enters the body through the nose from freshwater sources. 

The Naegleria fowleri ameba then travels up the nose to the brain where it damages the brain tissue. This infection cannot be spread from one person to another, and it cannot be contracted by swallowing contaminated water.

People can take actions to reduce the risk of infection by limiting the amount of water going up the nose. These actions could include:

-- Hold your nose shut, 

-- use nose clips, or 

-- keep your head above water when taking part in activities in bodies of warm freshwater, especially if you jump or dive into the water.

-- Avoid putting your head under the water in hot springs and other untreated thermal waters.

-- Avoid water-related activities in warm freshwater during periods of high-water temperature.

-- Avoid digging in, or stirring up, the sediment while taking part in water-related activities in shallow, warm freshwater areas. Naegleria fowleri amebas are more likely to live in sediment at the bottom of lakes, ponds and rivers.

-- Those who experience the following symptoms after swimming in any warm body of water should contact their health care provider immediately as the disease progresses rapidly:

- Severe headache.

- Fever.

- Nausea.

- Vomiting.

- Stiff neck.

- Seizures.

- Altered mental status.

- Hallucinations.

For more information about Naegleria fowleri, visit the CDC’s webpage. 

Source: Department of Health, https://content.govdelivery.com/accounts/MODHSS/bulletins/3edbd58

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