PRO/AH/EDR> Streptococcus equi – USA: (WA) zoonotic, subsp. equi, susp.


A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases

Date: Tue 15 Aug 2023
Source: Paulick Report [edited]

A 70-year-old woman whose horse was ill with strangles contracted the
disease, reports researchers from the University of Washington School
of Medicine.

In horses, strangles is highly transmissible, but it is very rare that
the disease is transmitted to humans. Transmission to humans may be
caused when the person is exposed to secretions that contain a large
amount of pathogens.

The woman presented to the emergency department with nausea, dry
heaves, fever, chills, and shakes. She also had a significant cough,
but no shortness of breath. She had no recent illness or
immune-compromising medical conditions, and she took no prescription

Cracking sounds could be heard in her lungs, and a CT scan showed
patchy, ground-glass opacities that might indicate partial lung
collapse or an atypical infection. She was admitted to the hospital
and IV antibiotics were begun. The woman had early sepsis and

One day after admission and beginning treatment, her blood pressure,
heart rate, respiration rate, and temperature were back within normal

A PCR test on the woman’s blood showed that she was positive for
Streptococcus and she was advised to remain in the hospital. Six
days before admittance to the hospital, the woman had found her horse
looking ill and having trouble breathing. It died the next day, with
blood and mucus coming from its mouth and nose. She held the horse as
he died.

Researchers said this was the most likely cause of the horse-to-human
transmission of the disease, though this cannot be absolutely

Two days after admission, the woman was discharged while on
amoxicillin and remained symptom free during her recovery.

There are only 5 Streptococcus equi subspecies equi infection cases
in humans that have been reported worldwide. This case is the only
horse-to-human case in the United States in the last 40 years.

The scientists note that individuals who are immunocompromised, who
have cardiovascular disease, or who have a neurologic susceptibility
are at higher risk of contracting the disease. Penicillin appears to
be the proper treatment for S. equi infections in horses and

Medical intervention is necessary to prevent an S. equi infection
from causing significant issues in humans, like meningitis,
bacteremia, or death, they conclude.

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