First Case of Novel Influenza A (H5N1) in Texas, March 2024

The Texas Department of State Health Services (DSHS) is reporting the first human case of novel avian influenza A(H5N1) in Texas. The patient became ill following contact with dairy cows presumed to be infected with avian influenza. The patient’s primary symptom was conjunctivitis. This is the second case of avian influenza A(H5N1) identified in a person in the United States and is believed to be associated with the recent detections of avian influenza A(H5N1) in dairy cows announced by the Texas Animal Health Commission. DSHS along with local, regional, state, and federal partners, is investigating this ongoing situation. Avian influenza A(H5N1) viruses have only rarely been transmitted from person to person. As such, the risk to the general public is believed to be low; however, people with close contact with affected animals suspected of having avian influenza A(H5N1) have a higher risk of infection.

DSHS is issuing this health alert to provide awareness to healthcare providers and ask them to be vigilant for people with signs and symptoms of avian influenza A(H5N1). Suspicion for avian influenza A(H5N1) should be heightened for people who have had contact with animals suspected of having avian influenza A(H5N1).

In March 2024, samples were collected and tested for influenza from several animals in Texas and Kansas. These animals, including wild birds, cats, and dairy cows, were tested because they exhibited signs of illness. Some of the animals tested positive for influenza. Further testing of these samples indicated the presence of avian influenza A(H5N1). This is the first time avian influenza A(H5N1) has been detected in cattle in the United States. DSHS, including regional staff have been working with other state and federal health agencies to investigate suspect cases of avian influenza A(H5N1) in both humans and animals.

The USDA and state animal health agencies routinely conduct surveillance for avian influenza A viruses in poultry in the United States and have previously detected the same strain of influenza A(H5N1) in backyard poultry flocks in Texas. Highly Pathogenic Avian Influenza Detected in Moore County Birds (texas.gov); HPAI Confirmations in Commercial and Backyard Flocks (usda.gov)

Although not commonly associated with seasonal influenza, conjunctivitis has been observed in avian influenza A virus infections. Because of this, healthcare providers including optometrists and ophthalmologists, should be aware of the potential of individuals presenting with conjunctivitis who have had exposure to affected animals.

Illness in humans with avian influenza A(H5N1) virus have ranged from mild to severe. Reports of severe avian influenza A(H5N1) illness in humans have included fulminant pneumonia leading to respiratory failure, acute respiratory distress syndrome, septic shock, and death.

If providers encounter a patient with symptoms compatible with avian influenza A(H5N1) infection and exposure to affected animals is suspected, they should immediately consult their local health department.

Infection Control

Facilities should follow their normal infection control procedures when assessing patients presenting with respiratory illness. Standard, contact, and airborne precautions are recommended for patients presenting for medical care or evaluation who have illness consistent with influenza and recent exposure to animals or humans potentially infected with avian influenza A(H5N1), and for patients with confirmed influenza A(H5N1). Additional guidance on infection control in healthcare settings can be found on the Center for Disease Control and Prevention’s (CDC) website (Interim Guidance for Infection Control Within Healthcare Settings When Caring for Confirmed Cases, Probable Cases, and Cases Under Investigation for Infection with Novel Influenza A Viruses Associated with Severe Disease).

Treatment and Chemoprophylaxis

Initiation of antiviral treatment with a neuraminidase inhibitor is recommended as soon as possible for any patient with suspected or confirmed infection with avian influenza A(H5N1). This includes patients who are presumed, confirmed, or probable cases, or persons under investigation (PUIs). A PUI is an individual with a documented exposure to avian influenza A(H5N1) and has developed symptoms compatible with avian influenza A(H5N1) infection. Treatment should be initiated even if more than 48 hours has elapsed since illness onset and regardless of illness severity (outpatients or hospitalized patients). Treatment with oseltamivir (twice daily for 5 days) is recommended regardless of time since the onset of symptoms. Antiviral treatment should not be delayed while waiting for laboratory test results. Providers should use their clinical judgement when determining treatment for patients whose symptoms are nearly resolved.

Additional guidance on evaluating and managing patients can be found on the CDC’s websites:

• Brief Summary for Clinicians: Evaluating and Managing Patients Exposed to Birds Infected with Avian Influenza A Viruses of Public Health Concern
• Interim Guidance on the Use of Antiviral Medications for Treatment of Human Infections with Novel Influenza A Viruses Associated with Severe Human Disease
• Highly Pathogenic Avian Influenza A(H5N1) Virus in Animals: Interim Recommendations for Prevention, Monitoring, and Public Health Investigations | Avian Influenza (Flu)

The recommendation for administration of chemoprophylaxis in asymptomatic individuals that have potentially been exposed to avian influenza A(H5N1) depends on the nature of the exposure. Chemoprophylaxis should be administered to individuals in the same household or close family members with unprotected, prolonged contact to a confirmed or probable case. Chemoprophylaxis may be considered in healthcare personnel or non-household members with prolonged unprotected close contact with a confirmed or probable case. Chemoprophylaxis is typically not considered for individuals who have had social contact of a short duration with a confirmed or probable case in a non-hospital setting. For asymptomatic individuals, the treatment frequency dosing for oral oseltamivir or inhaled zanamivir (one dose twice daily) is recommended instead of the typical antiviral chemoprophylaxis regimen (once daily).

Chemoprophylaxis for symptomatic individuals that have had contact with a confirmed or probable case is recommended. Treatment should be started immediately and not be delayed while testing is pending.

Additional guidance on chemoprophylaxis for individuals that have had contact with suspect or confirmed cases can be found on the CDC’s website (Interim Guidance on Follow-up of Close Contacts of Persons Infected with Novel Influenza A Viruses and Use of Antiviral Medications for Chemoprophylaxis).

Novel influenza A including avian influenza A(H5N1) is a notifiable disease condition in Texas and must be reported immediately.

Local and regional health departments should investigate all suspected, probable, or confirmed avian influenza cases and perform public health follow-up on close contacts. Please refer to the DSHS Emerging and Acute Infectious Disease Guidelines- Influenza A-Novel/Variant for conducting a case investigation and performing public health follow-up.

A close contact is defined as a person who is within about 6 feet of a confirmed or probable avian influenza case for a prolonged period of time, or who had direct contact with infectious secretions while the case was likely to be infectious (beginning 1 day prior to illness onset and continuing until the resolution of illness).

For information regarding the use of personal protective equipment during a probable or confirmed avian influenza case investigation visit the following website: Recommendations for Worker Protection and Use of Personal Protective Equipment (PPE) to Reduce Exposure to Novel Influenza A Viruses Associated with Severe Disease in Humans.

Although this is an evolving situation, the risk to the general public is low. People can protect themselves against flu by washing their hands often, covering their coughs and sneezes, not picking up dead birds and animals, and staying home if sick.

Routine antiviral treatment, such as Tamiflu (oral oseltamivir), is known to be effective against flu. If you suspect you have influenza, discuss treatment options with your healthcare provider.

Milk and milk products provide numerous health benefits. However, raw unpasteurized milk can make people sick. Pasteurization is the process of heating milk to a high enough temperature for enough time to kill harmful germs in the milk, including all kinds of flu viruses. Milk sold in stores is required to be pasteurized and is safe to drink.

• DSHS Influenza (Flu)
• CDC Avian Flu
• CDC Highly Pathogenic Avian Influenza A(H5N1) Virus in Animals: Interim Recommendations for Prevention, Monitoring, and Public Health Investigations
• Texas Animal Health Commission 2022-2024 Highly Pathogenic Avian Influenza
• USDA Highly Pathogenic Avian Influenza (HPAI)