Nature: Host factors, inflammatory markers, and clinical outcomes of Naegleria fowleri meningoencephalitis

 

#19,197

Nearly every year I end up blogging about a rare, mostly fatal brain infection caused by free living amoebas (Naegleria fowleri) that inhabit warm, fresh water (see A Reminder About Naegleria Season - 2019).

Dubbed the `brain eating amoeba' by the press - this infection is called PAM (Primary amebic meningoencephalitis) - and occurs when the amoeba enters the brain through the nasal passages, usually due to the forceful aspiration of contaminated water into the nose.

Not every PAM case is due to Naegleria, as Balamuthia mandrillaris and Acanthamoeba - and other non-Naegleria amoebic infections - can cause similar pathologies. 

As a thermophilic (heat-loving), free-living amoeba, it is hardly surprising that Naegleria is mainly reported during the summer - and that Florida and Texas lead the nation in cases over the past three decades - although infections have occurred as far north as Minnesota.

Last year the CDC's MMWR carried a report on a fatal 2024 case from Texas, which involved a previously health 71-year old woman who used unsterilized water to perform nasal irrigation.  

This is a common way that people around the world have become infected (see 2011's Neti Pots & Naegleria Fowleri).  The CDC and state health departments have long warned on the dangers of using tap water to perform nasal irrigation, and offer advice on safer alternatives. 

For a more detailed look as PAM risks from nasal irrigation, you may with to revisit EID Journal: (Mis)perception and Use of Unsterile Water in Home Medical Devices.

Other routes of infection include swimming in stagnant, warm fresh water ponds, attending water parks, and even in a child playing with a water hose in their own yard. 

Only 3 or 4 cases are reported in the United States each summer, but in 2017 a research letter written by epidemiologists at the CDC (see EID Journal: Estimation of Undiagnosed Naegleria fowleri (PAM), United States) estimated the yearly number PAM cases in the United States probably averages closer to 16 (8 males, 8 females).

Meaning that 70%-80% likely go unrecognized. 

Every year Pakistan reports a dozen or more infections from this `killer amoeba’, as chlorination of their water supplies is often inadequate, and for many, nasal ablutions are part of their daily ritual.

But in 2025 Kerala, India saw an unprecedented outbreak (see The outbreak of amoebic meningoencephalitis in Kerala: A wake-up call) `with with reports indicating a total of 129 cases and 26 deaths as of October 18, 20251.'

Even more remarkable than the sharp rise in cases was the unusually low fatality rate - which normally exceeds 90% - even with treatment. 

Since it was published 2 weeks after the Hantavirus outbreak aboard the m/v Hondius and 4 days after the announcement of a large Bundibugyo virus outbreak in Africa, the following study - published in Nature - probably didn't garner as much attention as it should.

In short, this study looked at a cohort of roughly 200 PAM patients from Kerala, India treated between January and November 2025 using a standardized amphotericin B/miltefosine protocol. 

Roughly of 1/3rd of cases were unresolved at the time of the cut off, and were not included in the analysis - but of the 134 who were -  61 died,  while 73 recovered, giving a case fatality rate of 45.5%. 

Given this remarkable success rate, and the increasing risk of PAM due to climate change, the following report should be of particular interest to clinicians.

Host factors, inflammatory markers, and clinical outcomes of Naegleria fowleri meningoencephalitis

Vijeesh Kadukkatti, Brijil K. Mathew & Peter Mac Asaga
Communications Medicine volume 6, Article number: 290 (2026) 

Abstract

Background

Primary amoebic meningoencephalitis (PAM) caused by Naegleria fowleri carries historical case fatality rates (CFR) exceeding 97%. The 2025 Kerala outbreak, the largest documented globally, provided an unprecedented opportunity to identify host factors and inflammatory correlates influencing survival under standardised management.

Methods

We conducted a prospective observational study of 200 laboratory-confirmed PAM cases across six districts of Kerala, India (January–November 2025). All patients received protocolised amphotericin B ± miltefosine. Demographic, clinical, and laboratory data were collected, including inflammatory biomarkers (IL-6, TNF-α, IL-1β, neutrophil-to-lymphocyte ratio), pathogen burden (qPCR), and treatment timing. Multivariable logistic regression identified mortality predictors; bootstrap resampling and E-value sensitivity analyses assessed robustness.

Results

Here we show that among 200 patients (median age 41 years; 50% male), 134 with resolved outcomes yield a CFR of 45·5% (95% CI 37·3–54·5%; 61 deaths, 73 recoveries). Diabetes mellitus is the only statistically significant predictor of mortality in the adjusted model (adjusted OR 2·59; 95% CI 1·01–6·66; p = 0·048), though the proximity of the lower confidence bound to unity warrants cautious interpretation. This association remains consistent across sensitivity analyses (bootstrap 95% CI 1·06–8·74; E-value 4·62). Asthma demonstrates a protective association in univariable analysis (OR 0·37; p = 0·021), though this finding remains hypothesis-generating. Early treatment (≤2 days) shows a trend toward improved survival (p = 0·084). Inflammatory biomarkers show no association with outcome, though CSF pathogen burden correlates significantly with admission neurological severity.

Conclusions

Under standardised treatment, diabetes mellitus emerges as a key host determinant of PAM mortality. The dissociation between inflammatory markers and outcomes suggests neurological fate may be determined early in infection, with immediate clinical implications as climate change expands the geographic range of N. fowleri.

Plain language summary

Naegleria fowleri is an amoeba found in warm freshwater that can cause a rare but usually fatal brain infection. Historically, more than 97% of people who develop this infection die. In 2025, a large outbreak occurred in Kerala, India, affecting 200 people. We studied these patients to understand what factors influenced survival. The death rate was 45.5%, much lower than expected, likely because all patients received the same standard drug treatment. People with diabetes were roughly twice as likely to die as those without. Surprisingly, common markers of inflammation did not help predict who would survive. As climate change warms freshwater sources worldwide, understanding what determines survival from this infection becomes increasingly important.

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Preprint: The canine respiratory epithelium is a permissive ecosystem for influenza interspecies transmission and emergence

 

#19,196

Until 2004, dogs were considered relatively immune to influenza, but that changed abruptly when an equine H3N8 virus spilled over to dogs at a Florida racetrack, and began its world tour.

Three years later, an avian H3N2 virus spilled over to dogs in South Korea, and spread across Asia, eventually arriving in the United States in 2015.

In 2010, in Morens & Taubenberger on Influenza’s History, we looked a a fascinating 11-page historical review of Influenza outbreaks amongst a variety of hosts (human, avian, equine, porcine, canine, etc.) going back more than 3,000 years by Jeffrey K. Taubenberger and David Morens.

They cited a number of pandemics where anecdotal accounts mentioned dogs falling ill, either before - or concurrent to - when human cases emerged.

Since then we've looked at a lot of studies on dogs and flu, including: 

• In late 2012, in China: Avian-Origin Canine H3N2 Prevalence In Farmed Dogs, we looked at a study that found a newly emergent avian origin H3N2 virus prevalent in pet and farmed dog populations in southern China.

• In 2015, in Korea Finds More Dogs With H5N8 Antibodies, we saw evidence of HPAI infection in dogs. 

• Also in 2014, in Study: Dogs As Potential `Mixing Vessels’ For Influenza - we looked at the ability of different influenza strains (canine, equine and human) to infect, and replicate in, canine tracheal tissues. 

• In 2015, researchers reported finding Influenza A(H6N1) In Dogs, Taiwan

• Again in 2015, in Virology J: Human-like H3N2 Influenza Viruses In Dogs - Guangxi, China, we looked at the discovery two H3N2 CIVs possessing high homology with human/swine influenza viruses.

• In 2023 we looked at a lengthy (57-page) preprint called Increased Public Health Threat of Avian-origin H3N2 Influenza Virus During Evolution in Dogs from researchers in China who warned on the continued evolution of canine H3N2, which appears to be moving towards becoming a more `humanized' virus.

• More recently (2025) we looked at A Brief History of Influenza A in Canines & Canadian Report On A Recent Fatal H5N1 Dog Infection.

While dogs are more apt to have less severe flu illness than cats - making infections easier to miss - there is little doubt they are susceptible.  Unknown, however, is whether they are mostly a dead-end host, or if they are capable to transmitting the virus to others. 

Today we've got a preprint from researchers in the UK which attempts to better understand the risks. Using canine lung explants, they find that dogs are a plausible host for influenza reassortment, as they contain both human-type (α2,6) and avian-type (α2,3) receptor cells.

The caveats being that this is an ex vivo study, and is subject to a number of limitations (see below), and there is currently no evidence that novel influenza viruses are spreading efficiently among canines. 

But the only constant with influenza viruses is that they change, making today's status tenuous at best.  Due to its length, I've only posted some excerpts. Follow the link to read the report in its entirety.  

The canine respiratory epithelium is a permissive ecosystem for influenza interspecies transmission and emergence
Hanting Chen, Jack Hassard, Jiayun Yang, Callum Magill, Toby Carter, Jean-Remy Sadeyen, Aimi Ito, Clio Duerr,  Hannah Rose Montgomery, Savitha Raveendran, Kieran Dee,  Maximillian N J Woodall, Grace B Tyson, Maria M Afonso, Verena Schultz,  Claire Mary Smith,  Margaret J Hosie, Stuart Haslam, Munir J Iqbal,  Pablo R Murcia

doi: https://doi.org/10.64898/2026.06.04.730051
This article is a preprint and has not been certified by peer review 

Preview PDF

Abstract

The outcome of virus spillover ranges from dead-end infections to pandemics and is underpinned by host-pathogen interactions as well as evolutionary and epidemiological processes. The emergence of novel influenza A viruses (IAVs) has been associated with reassortment events involving multiple species, highlighting the importance of reservoir and intermediate hosts in viral emergence.

Highly pathogenic H5N1 IAVs of the 2.3.4.4b genotype have caused a panzootic affecting a broad range of mammals. The role of dogs -arguably the most popular companion animal and a natural host of IAVs- in the ecology of IAVs under this new zooepidemiological scenario is unknown. To address this, we characterised the glycome of the dog respiratory epithelium, infected canine tracheal explants with multiple IAVs (including canine H3N2 and H3N8, equine H3N8, avian H3N8 and H5N1, swine H1N1, human H1N1 and H3N2, and bovine H5N1 viruses), and determined their cellular tropism.

We show that the respiratory tract of dogs presents abundant sialylated glycans known to act as IAV receptors. Further, most IAVs (including 2.3.4.4b viruses) infected and replicated in dog tracheas, targeting mainly ciliated cells. Serological testing showed evidence of influenza spillover infections in dogs from the UK.

Overall, our results show that the canine respiratory tract can provide a suitable environment for the generation of new IAVs. Given the multi-host contact networks of dogs in nature, they could act as recipients, bridging hosts, and/or mixing vessels for multiple IAV lineages, playing a central role in the ecology of influenza emergence.

(SNIP) 

Our results suggest that dogs could act as a bridging species for the emergence of novel IAVs, including the H5N1 2.3.4.4b genotype. Serological studies in North America and Europe show that hunting dogs are routinely exposed to H5N1 IAVs 53,54. 

Vaccination of high-risk dog subpopulations could reduce the risk ofinter species infections (avian-to-dog and dog-to-human) and should be considered as preventative measures. 

This study has various limitations. Tracheal explants represent a significant portion of the airways, but this experimental system does not include the upper respiratory tract, the bronchial tree, nor the pulmonary parenchyma, which are likely to exhibit different virus/host interactions due to the presence of different cell types.

Further, explants lack systemic responses that are normally mounted during viral infections. Despite these limitations, our results are consistent with observations reported in field studies 59,60 and experimental in vivo infections 26,27

In sum, influenza spillover and emergence require a succession of processes that occur at different scales8. As the canine respiratory tract is a suitable ecosystem for IAV infection and reassortment and dogs routinely interact with multiple species that support endemic IAVs, dogs could facilitate the flow of virus between sympatric species. Targeted approaches to reduce the risk of IAV infections in dogs should be part of preparedness efforts to control influenza cross-species switching. 

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USDA: 2 More Screwworm Detections in Texas

 
USDA Screwworm Dashboard -Updated

Update: The USDA has clarified that the dog mentioned infected in yesterday's post was from New Mexico, not Texas. 

 #19,195

Although the USDA's website and Screwworm Dashboard (above) have not been updated yet, this morning the USDA emailed the following update, which adds two more cases - and importantly - from 2 new counties. 

The calf in La Salle county is adjacent to Zavala County, where the first two cases were identified, but the dog in Andrews County is roughly 300 miles north and west.  

There is a possibility the dog was exposed in Mexico, but the epidemiological investigation is ongoing. I'll update this post when the USDA updates their website.
           

        (via Email)

USDA Confirms Two Additional Cases of New World Screwworm in the United States

The State of Texas continues to lead response with USDA support.

WASHINGTON, D.C., June 8, 2026 – Today, the U.S. Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) confirmed two additional cases of New World screwworm (NWS) in the United States – a calf in La Salle County, Texas, and a dog in Andrews County, Texas.

Epidemiological investigations are ongoing for both cases. A veterinarian in Andrews County submitted the samples from the infested dog. Details on this case will be shared as they are available, but early reports indicate the dog was recently in Mexico.

NWS is a serious pest that threatens livestock, pets, wildlife, and, in rare cases, people. The larvae burrow into the living tissue of animals, causing severe wounds, animal suffering, and significant economic losses.

“Over the past week, USDA has identified and expeditiously confronted four confirmed detections of New World screwworm. While we address these instances that require immediate attention, and continue to sample suspected cases, we are simultaneously working to eradicate the pest entirely,” said Dudley Hoskins, Under Secretary for Marketing and Regulatory Programs. “We need the partnership of animal owners across the region – please stay vigilant, check your animals closely, and report anything that looks suspicious. Together, we can protect our livestock, our communities, and the health of animals nationwide.”

USDA and TAHC Response

USDA and the Texas Animal Health Commission (TAHC) continue to lead an aggressive unified response, with a total of 75 people actively responding on the ground and hundreds of additional people around the country providing laboratory diagnostics, logistics, treatment distribution, air operations, outreach, operational planning, and resource support for the response. APHIS and TAHC will continue to surge additional trained personnel as needed to ensure an effective response.

For each new case, USDA and TAHC implement actions outlined in the NWS Response Playbook, including:

• Establishing and maintaining a 20km infested zone with quarantines, movement controls, and heightened surveillance around confirmed detections
• Increasing trapping along the border and outside the dispersal zone
• Conducting surveillance and management strategies in wildlife
• Implementing targeted outreach to local producers, veterinarians, and communities

Intensified Sterile Fly Releases

USDA continues to release sterile flies over and just outside of the infested areas. To ensure sterile fly release operations can be deployed to affected areas in Texas and in northern Mexico near the border as quickly and efficiently as possible, USDA has activated the sterile fly dispersal facility at Moore Air Base in Edinburg, Texas. Sterile pupae arrived at the facility on Friday, and aerial dispersal flights originating from the base will begin tomorrow.

Because it is important to continue ongoing surveillance efforts while releasing sterile insects, it is possible that sterile NWS flies could be caught and/or reported. To ensure officials can tell the difference between sterile and wild NWS flies, USDA dyes the sterile pupae, and the dye transfers to the sterile flies when they hatch. The fluorescent green or orange dye glows under UV light and may also be visible to the naked eye. If a sterile fly is captured in a trap, this dye allows animal health officials to quickly rule the fly out as a threat. 

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EM&I: A new clade of H9N2 avian influenza virus circulating in Laos

 
In terms of risk of emergence, the H9N2
Y280 lineage is ranked higher than H5N1

#19,194

While LPAI H9N2 may not be the most headline grabbing avian flu virus, it is quite likely the most versatile. It is highly promiscuous, reassorting easily with many other subtypes (including H5Nx and H7Nx), it has diverged into numerous clades, and it continues to accrue mammalian adaptations.  

While testing and reporting of cases around the globe is limited, over the past 12 months more than 2 dozen human cases have been reported (see FluTrackers H9N2 case list).

As a result, H9N2 gets more than a little attention by researchers.

• Last month, in Preprint: Outbreak of H9N2 Avian Influenza Viruses in Lesser Rhea in Peru, June-July 2025, we learned of a newly identified - and highly virulent - South American strain of H9N2. 

• Also last month, in Eurosurveillance: Cross-reactive human antibody responses to H9N2 influenza virus, New York, United States, 2025, we saw that ` pre-existing immunity to H9N2 in humans that is dominated by cross-reactive but largely non-neutralising antibodies, with a greater contribution from NA-directed responses.'

• Last October, in China CDC Weekly: Epidemiological and Genetic Characterization of Three H9N2 Viruses Causing Human Infections, investigators reported a number of indicators of increased mammalian adaptation within the virus, including an enhanced ability to infect upper respiratory (α2,6-sialic acid) tract receptors, and a number of HA protein mutations, including; H191N, A198V, Q226L, and Q234L.

• The Asian Y280/G57 lineages have shown increasing signs of mammalian adaptation (see EM&I: Enhanced Replication of a Contemporary Avian Influenza A H9N2 Virus in Human Respiratory Organoids)), while the African and Middle Eastern Lineages (mostly European G1-like) are older and less evolved.

All of which brings us to a new report, published last week in Emerging Microbes & Infections, which describes a new clade of LPAI H9N2 recently discovered in Laos. 

A new clade of H9N2 avian influenza virus circulating in Laos

Jiaming Li ,Chunge Zhang ,Ren Li ,Yanqing Wang ,Rahat Ullah Khan ,Ruichang Quan 

Article: 2678641 | Received 05 Feb 2026, Accepted 19 May 2026, Published online: 04 Jun 2026
https://doi.org/10.1080/22221751.2026.2678641

ABSTRACT

In 2024, we identified and sequenced 52 avian influenza A (H9N2) virus strains in Laos. Using the established H9N2 genomic classification system, a novel HA gene clade of the A/chicken/Beijing/1/94-like (BJ/94-like) lineage, designated Clade 4.6.20, was identified.

This new clade is phylogenetically distinct from the previously described clades, and the representative strains in this new Clade 4.6.20 presented a low cross reactivity to the antisera of other clades, suggesting antigenic drift of the viruses between the new Clade 4.6.20, and other clades in the dominant lineage of Clade 4.6.

In addition, all the newly identified viruses in Clade 4.6.20 possessed HA-L226 and NP-N52 mutations, which are associated with human-type receptor binding and human MxA-related innate immunity escape, respectively.

Our findings underscore the necessity of global surveillance network and cooperation to monitor the evolution of AIVs, update vaccine seed strains, and develop new vaccines with high effectiveness against H9N2 AIVs circulating globally, which threaten poultry and human health.

        (SNIP)

In conclusion, the identification of a novel H9N2 clade (Clade 4.6.20) in Laos suggests that influenza viruses including both avian and human viruses may undergo undetected evolutionary changes in regions with inadequate surveillance, posing significant public health threats. This highlights the need to enhance international collaboration, improve surveillance systems, and develop new vaccines and NPIs to mitigate the increasing risks associated with cross-border viral spread and zoonotic transmission.

        (Continue . . .) 

This is the second `novel' LPAI H9N2 virus discovery reported in less than a month, and it comes just a couple of months after Europe's first imported H9N2 case (from West Africa). 

While primarily an avian virus, LPAI H9N2 has a track record of also  infecting humans, pigs, and even bats (see Preprint: The Bat-borne Influenza A Virus H9N2 Exhibits a Set of Unexpected Pre-pandemic Features).

China's attempts to control this rapidly evolving H9N2 virus with poultry vaccines have proved disappointing (see J. Virus Erad.: Ineffective Control Of LPAI H9N2 By Inactivated Poultry Vaccines - China).

And last year, in NPJ Vaccines: Impact of Inactivated Vaccine on Transmission and Evolution of H9N2 Avian Influenza Virus in Chickens, we saw evidence that not only had inactivated vaccines failed to prevent - or even reduce - H9N2 in China's poultry, they may have driven viral evolution (including mammalian adaptations).

Despite all of this - because it is not a high-risk H5 or H7 avian virus - H9N2 remains a `non-reportable' disease in poultry (see Terrestrial Animal Code Article 10.4.1.), allowing much of its spread and evolution to fly under the radar.

Hopefully these recent reports will spur additional surveillance, because - contrary to popular belief - what we don't know can hurt us. 

ECDC MERS-CoV Update: 2 Cases Reported By Saudi Arabia in 2026

#19,193

Although the number of MERS-CoV cases reported over the past few years has fallen dramatically, this high morbidity/mortality coronavirus continues to pose a significant public health threat ((Referral) Nature: Human MERS-CoV cases are falling but pose an ongoing pandemic threat) as it spreads and evolves in camels in the Middle East and Africa. 

Admittedly, we've seen more than a little reluctance on the part of Middle Eastern nations to report cases.  And it seems likely that cases are being missed in North and Central Africa as well (see EID Journal: Geographic Distribution of MERS-CoV among Dromedary Camels, Africa).

Both EID Journal: Estimation of Severe MERS Cases in the Middle East, 2012–2016 and Presence of Middle East respiratory syndrome coronavirus antibodies in Saudi Arabia: a nationwide, cross-sectional, serological study by Drosten & Memish et al., suggest that far more MERS-CoV cases have occurred than have been reported.

Last December, France reported 2 Travelers Returning From Arabian Peninsula Diagnosed with MERS-CoV, but thus far in 2026 all has been quiet. Saudi Arabia only reports every 6 months, but last Friday the ECDC carried a very brief report on two recent (March & April) cases.

Details are scant, but we know that one case was fatal, and the source of exposure for both cases are unknown. First the report, then I'll return with a bit more after the break.

Middle East respiratory Syndrome coronavirus (MERS-CoV) – Multi-country –Monthly update

Overview

Update: Since the previous update on 4 May 2026, and as of 1 June 2026, two new MERS cases, including one fatality, in Saudi Arabia have been reported by the World Health Organization (WHO) Eastern Mediterranean Regional Office (EMRO). Both cases are male adults and have unknown source of infection. One case had date of reporting in March 2026 and the fatal case had date of reporting in April 2026.

Summary: Since the beginning of 2026, and as of 1 June 2026, two MERS cases, including one fatality, have been reported in Saudi Arabia.

Since April 2012, and as of 1 June 2026, a total of 2 649 MERS cases, including 960 deaths, have been reported by health authorities worldwide. 

Sources:  ECDC MERS-CoV page | WHO MERS-CoV | ECDC factsheet for professionals | Qatar MoPH Case #1 |Qatar MoPH Case #2 | FAO MERS-CoV situation update | WHO DON Oman | WHO DON Saudi Arabia | WHO DON UAE | WHO DON Saudi Arabia 1 | WHO IHR | WHO EMRO MERS Situation report | WHO DON Saudi Arabia 2 |WHO DON Saudi Arabia 3 | WHO DON Saudi Arabia 4 | WHO DON Saudi Arabia 5 | MERS-CoV Dashboard | French Ministry of Health | WHO DON France & Saudi Arabia 

ECDC assessment 

Human MERS cases continue to be reported in the Arabian Peninsula. However, the number of new cases detected and reported through surveillance has dropped to the lowest level since 2014. The probability of sustained human to-human transmission among the general population in Europe remains very low and the impact of the disease in the general population is considered low. The current MERS-CoV situation remains unchanged and poses a low risk to the EU/EEA, as stated in the Rapid Risk Assessment published by ECDC on 29 August 2018.

ECDC published a technical report, 'Health emergency preparedness for imported cases of high-consequence infectious diseases', in October 2019 that is still useful for EU Member States wishing to assess their level of preparedness for a disease such as MERS. ECDC also published 'Risk assessment guidelines for infectious diseases transmitted on aircraft (RAGIDA) – Middle East respiratory syndrome coronavirus (MERS-CoV)' on 22 January 2020.ActionsECDC is monitoring this situation through its epidemic intelligence activities and reports on a monthly basis or when  new epidemiological information is available

Prior to COVID's emergence in late 2019, MERS-CoV was the top contender for sparking a coronavirus pandemic, sporting a high mortality rate (>30%), and spreading easily through hospitals in the Middle East (and South Korea) (see Ziad Memish: Two MERS-CoV Hospital Super Spreading Studies).

A year ago we looked at an editorial in Journal of Epidemiology & Global Health on the importance of continued healthcare preparedness and surveillance (see Al-Tawfiq & Memish On Recurrent MERS-CoV Transmission in Saudi Arabia), with an emphasis on identifying asymptomatic carriers.

Whether MERS-CoV will re-emerge as a global health threat remains unknown, but it continues to circulate  and evolve - largely out of our view - on both the Arabian Peninsula and in Africa.

Which makes it very much worth our attention.  

USDA & Texas Announce 2nd New World Screwworm Detection

 
Credit USDA

#19,192

Three days ago we saw the USDA Confirm the Presence of New World Screwworm (NWS) in the United States (Texas) for the first time since the 1960s.  The NWS is a parasitic fly that lays its eggs in the open wounds of warm-blooded animals (often cattle and deer, but occasionally humans and pets).

Unlike most fly maggots, NWS larva consume and burrow into living tissue, causing substantial morbidity and mortality. (See ASM 2025 Review New World Screwworm: Rise, Fall and Resurgence).

Not unexpectedly, this weekend we are learning of a 2nd case, found in a calf a little more than 5 miles away from the first case. 

Although the risk to public health is extremely low, this agricultural pest can be devastating for the cattle industry. 

The Texas Governor's office has officially declared two counties ( Zavala & Uvalde) as disaster areas, and has committed the full resources of the state to combat the threat. 

Governor Abbott Deploys State Resources To Combat New World Screwworm

June 5, 2026 | Austin, Texas | Press Release

Issues Disaster Declaration for Zavala and Uvalde Counties

Governor Greg Abbott today received a briefing and updated Texans on the state’s response following confirmation of a New World Screwworm (NWS) detection in Texas. The Governor also issued a disaster declaration for Zavala and Uvalde Counties.

“I am issuing an updated statewide disaster declaration to make two things very clear,” said Governor Abbott. “First, I authorize the use of all available resources of state government to respond to this disaster and reassign resources from across the state as needed to address NWS. Second, I am making all state personnel available to accelerate the movement of sterile flies into Texas and the construction of the new sterile screwworm production facility in Edinburg. We have eradicated this pest before, and we will do it again.”

        (Continue . . . )

Excerpts from the USDA's announcement follow:

Animal Health Officials Respond to Second Detection of New World Screwworm in the United States

FOR IMMEDIATE RELEASE
Contact: screwworm@usda.gov

WASHINGTON, D.C., June 5, 2026 — The U.S. Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) has confirmed a second detection of New World screwworm (NWS) after testing a number of suspect cases. The confirmed case was found in a one-month-old calf in Zavala County, Texas, approximately 5.6 miles away from the first confirmed detection. APHIS and our Texas partners continue to collect and test other samples from the surrounding area which have come back negative.

NWS is a serious pest that threatens livestock, pets, wildlife, and, in rare cases, people. The larvae burrow into the living tissue of animals, causing severe wounds, animal suffering, and significant economic losses.

“USDA has responded expediently with respect to this second detection, demonstrating our utmost preparedness. This second detection is within the established movement control zone and enhanced sterile insect dispersal area.” said Dudley Hoskins, Under Secretary for Marketing and Regulatory Programs. “Many models projected this pest would reach the United States last year, but thanks to USDA’s phenomenal work and our cooperation with state, federal, and industry partners, we’ve held it off until now—when we are far more prepared to respond. USDA has not wasted any time in this fight, we have defeated New World screwworm before, and we will do it again."

USDA Strike Team and Rapid Deployment Capacity

An APHIS strike team is already on-site in Texas. This team includes veterinary medical officers and animal health technicians – experienced experts who serve as USDA’s boots on the ground response force. APHIS is fully positioned to surge additional trained personnel as needed.

The National Veterinary Services Laboratories (NVSL) has deployed an entomologist to the USDA Agricultural Research Service laboratory in Kerrville, Texas, to expedite confirmation processes by positioning NVSL diagnostic assets in the area.

APHIS has also deployed two dedicated NWS response cargo trailers. Each 24-foot trailer serves as a mobile preparedness and field operations center. Once unloaded, the trailers convert into operational and laboratory space, providing USDA personnel with the equipment and environment necessary to mount a rapid, efficient response.

Treatment Resources and Supplies

The U.S. Food and Drug Administration has issued emergency use authorizations for several NWS treatments for different species. Currently, there are treatments available to support cattle, horses, swine, goats, captive exotic animals, and wildlife.

The National Veterinary Stockpile is actively procuring additional tools to treat and prevent NWS. USDA is working with federal and regulatory partners, and within federal purchasing processes, to secure more treatment options that are flexible, safe, and effective.

The National Veterinary Stockpile has relocated NWS treatment supplies to Texas to better support affected producers in the infested zone. If you or anyone you know needs access to these treatment supplies, they are now available and can be obtained by reaching out directly to the Texas Animal Health Commission (TAHC).

Intensified Sterile Fly Operations

As part of the established NWS eradication strategy, USDA began releasing sterile flies over the area on June 4. These missions will disperse 2 million sterile screwworms twice a week to disrupt the pest’s lifecycle.

In addition to aerial releases, USDA is shipping another 4 million sterile flies per week to Texas. These will be deployed using 24 ground release chambers, strategically placed in and around the detection zone to maximize impact.

(Continue . . . )