Infectious Disease Update – Sept ’24

There are a three important infectious disease updates to be aware of, especially if you work in the emergency department or urgent care. Whooping Cough, Eastern Equine Encephalitis, and MPox

Whooping Cough

Whooping cough, caused by the bacterium Bordetella pertussis, is characterized by severe coughing fits, often followed by a distinctive “whooping” sound on inhalation. While it can affect people of all ages, it’s particularly dangerous for infants and young children

In the U.S. cases significantly decreased in beginning in 2019, which the CDC attributed to the COVID-19 pandemic. Over the next 5 years, cases have gradually increased. This year, the number of cases has exceeded 2019’s pre-pandemic levels, with four times as many case by mid August 2024 as we saw this time last year.

With the rapid increase in cases, urgent care centers and emergency departments across the U.S. remain the front line of defense.

Early symptoms can last for 1 to 2 weeks and usually include:

• Runny or stuffed-up nose
• Low-grade fever (less than 100.4°F)
• Mild, occasional cough

Late symptoms occur 1 to 2 weeks after the first symptoms start, people may develop paroxysms, known as coughing fits. These coughing fits usually last 1 to 6 weeks but can last for up to 10 weeks. The cough generally gets worse and becomes more common as the illness continues.

Coughing fits can cause people to

• Make a high-pitched “whoop” when they inhale after a coughing fit
• Vomit during or after coughing fits
• Feel very tired after the fit, but usually seem well in-between fits
• Have difficulty sleeping at night
• Struggle to breathe
• Fracture (break) a rib

According to the CDC “Babies younger than 1 year old who are treated in the hospital can have:

• Apnea: 2 in 3 (68%)
• Pneumonia (lung infection): 1 in 5 (22%)
• Convulsions (violent, uncontrolled shaking): 1 in 50 (2%)
• Encephalopathy (disease of the brain): 1 in 150 (0.6%)
• One in 100 (1%) will die from their complications.”

Several factors contribute to the recent increase in whooping cough cases:

• Waning vaccine immunity: Protection from childhood vaccines can decrease over time [2].
• Vaccine hesitancy: Some parents are delaying or refusing vaccinations for their children [3].
• Improved diagnostic techniques: Better testing methods may be detecting cases that were previously missed [4].

The CDC recommends the following guideline for treatment:

• People 1 year of age and older within 3 weeks of cough onset
• Infants younger than 1 year of age within 6 weeks of cough onset
• Pregnant women (especially if near term) within 6 weeks of cough onset
• Post exposure prophylaxis for high risk exposures and close contacts is also recommended.
• Antibiotic choices include
  • Azithromycin
  • Clarithromycin
  • Erythromycin
  • Trimethoprim-sulfamethoxasole.

The primary strategy for preventing whooping cough is vaccination. The CDC recommends:

• DTaP vaccine for children younger than 7 years old
• Tdap vaccine for adolescents and adults, including pregnant women during each pregnancy [5]

For more: Diptheria, Pertussis, and Tetanus: Evidence-Based Management of Pediatric Patients in the Emergency Department

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Eastern Equine Encephalitis

The CDC reported 4 cases of encephalitis due to the Eastern Equine Encephalitis virus this year in the northeast U.S.. Human cases were reported in Wisconsin, Vermont, Massachusetts, and New Jersey. Non-human cases have also been reported in the northeast and southeast U.S..

EEE is a viral disease transmitted to humans through the bite of infected mosquitoes. It’s one of the most severe mosquito-transmitted diseases in the United States, with approximately 33% mortality and significant brain damage in most survivors of the encephalitic infection [6].

According to the CDC

• Eastern equine encephalitis virus circulates in the environment between mosquitoes and birds typically found in freshwater hardwood swamps.
• People and some other animals (e.g., horses and emus) become infected often by different mosquitoes (known as bridge vectors) that feed on both birds and animals.
• People and horses are considered “dead-end” hosts. This means they do not spread the virus, even though they get sick, to mosquitoes that bite them.
• Eastern equine encephalitis virus was transmitted through organ transplantation involving one organ donor and three organ recipients.

Infection can manifest in two ways:

• Systemic: Sudden onset of chills, fever, malaise, arthralgia, and myalgia. Many recover fully after 1-2 weeks of illness.
• Encephalitic: Fever, headache, irritability, restlessness, drowsiness, anorexia, vomiting, diarrhea, cyanosis, convulsions, and coma [7]

There is no specific treatment for the infection. Treatment consists of supportive care only.

For more: Emergency Department Management of Adults With Infectious Meningitis and Encephalitis

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MPox

The CDC is warning:

“Right now, the Democratic Republic of the Congo (DRC) is experiencing the highest number of suspected mpox cases on record in that country, with more than 22,000 suspected cases and more than 1,000 deaths. The clade of mpox virus that causes cases in DRC (clade I) is associated with a higher rate of severe disease than the clade that caused the ongoing global outbreak that began in 2022 (clade II).”

As of August 26th, 2024, “No cases of clade I mpox have been reported in the United States at this time” however cases have been reported in Sweden and Thailand.

Some important facts from the CDC

1. The number of illnesses reported recently is far below the peak of the outbreak in July and August 2022, when the national 7-day average was more than 450 cases a day (or more than 11,000 per month). Between January and September 2023, there were fewer than 180 cases reported per month. In October 2023, there was an uptick to about 250 that month. Case counts have remained consistent at about 250 a month since then.
2. In 2023, there were a total of 1,700 cases. So far in 2024, a total of 1,122 cases have been reported.
3. A new CDC study[8] indicates that getting two doses of mpox vaccine works to prevent mpox, yet only 23% of eligible people have received the vaccine. It’s very rare for people to get mpox after they’ve been fully vaccinated.
4. Most new mpox cases continue to be in people at higher risk for mpox who were not vaccinated with JYNNEOS.[9]
5. Wondering about boosters? The same CDC study[10] suggests that people who have received both doses do not need booster doses at this time. There have been a small number of infections in people who have been vaccinated, but vaccination is likely to make the infection milder and reduce the risk of severe infection and death.
6. The antiviral drug tecovirimat (TPOXX) has been used to treat mpox, especially people with severe mpox or who are likely to get severely ill. The safety and effectiveness of TPOXX are being evaluated through the STOMP clinical trial. If you know someone newly diagnosed with mpox, encourage them to join this trial to get access to TPOXX and help people in the future.

MPox typically presents with the following symptoms:

• Initial symptoms (1-3 days): fever, lymphadenopathy, back pain, headache, myalgia, and fatigue
• Rash progression (2-4 weeks): macules → papules → vesicles → pustules → scabs

The virus can be transmitted through:

• Animal-to-human contact: interaction with infected animals or consuming undercooked meat from infected animals
• Human-to-human transmission: primarily through large respiratory droplets (requiring prolonged face-to-face contact), direct contact with body fluids or lesion material, or indirect contact with contaminated items

For more: Diagnosis and Treatment of Sexually Transmitted Infections in Urgent Care

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References

1. Centers for Disease Control and Prevention (CDC). (2024). Pertussis (Whooping Cough). Retrieved August 28, 2024, from https://www.cdc.gov/pertussis/index.html
2. Burdin, N., Handy, L. K., & Plotkin, S. A. (2024). What Is Wrong with Pertussis Vaccine Immunity? The Problem of Waning Effectiveness of Pertussis Vaccines. Cold Spring Harbor Perspectives in Biology, 12(4), a035691. https://doi.org/10.1101/cshperspect.a035691
3. World Health Organization (WHO). (2024). Immunization, Vaccines and Biologicals: Pertussis. Retrieved August 28, 2024, from https://www.who.int/teams/immunization-vaccines-and-biologicals/diseases/pertussis
4. Guiso, N., & Taieb, F. (2024). Whooping Cough: A Disease Not to Be Underestimated. Microorganisms, 8(10), 1515. https://doi.org/10.3390/microorganisms8101515
5. Centers for Disease Control and Prevention (CDC). (2024). Whooping Cough Vaccination. Retrieved August 28, 2024, from https://www.cdc.gov/pertussis/vaccines.html
6. Centers for Disease Control and Prevention (CDC). (2024). Eastern Equine Encephalitis. Retrieved August 28, 2024, from https://www.cdc.gov/easternequineencephalitis/index.html
7. World Health Organization (WHO). (2024). Eastern equine encephalitis. Retrieved August 28, 2024, from https://www.who.int/health-topics/eastern-equine-encephalitis
8. Monkeypox Virus Infections After 2 Preexposure Doses of JYNNEOS Vaccine — United States, May 2022–May 2024
9. Monkeypox Virus Infections After 2 Preexposure Doses of JYNNEOS Vaccine — United States, May 2022–May 2024
10. Monkeypox Virus Infections After 2 Preexposure Doses of JYNNEOS Vaccine — United States, May 2022–May 2024