Protective maternal sphere symbolizing placental health.

Rare Haemophilus influenzae Infection: What Parents Need to Know

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Reese Marlowe in Health & Wellness August 2025 • 4 min read.

"A rare case highlights the importance of vigilance and advanced diagnostics in identifying and treating placental infections caused by Haemophilus influenzae, ensuring better outcomes for mothers and newborns."


Placental infections can pose significant risks during pregnancy, potentially leading to preterm deliveries and other complications. While many types of bacteria can cause such infections, one particularly rare culprit is Haemophilus influenzae (HI). Although commonly known for causing childhood illnesses like epiglottitis and otitis media, HI can occasionally cause severe infections in pregnant women and newborns.

A recent case study detailed in the American Journal of Clinical Pathology sheds light on a rare instance of Haemophilus influenzae placental infection. The study, led by Farhan Khan and Tammey Naab from Howard University Hospital, Washington, D.C., reported a case involving a 29-year-old African American woman who delivered a stillborn male fetus prematurely at 22 weeks of gestation. This case underscores the importance of recognizing atypical infections and utilizing advanced diagnostic methods to ensure timely and appropriate treatment.

This article aims to break down the key findings of this study, explaining the medical context in a clear, accessible manner. We will explore the nature of Haemophilus influenzae, the details of the reported case, and the broader implications for maternal and newborn health. By understanding this rare infection, parents and healthcare providers can be better prepared to identify and manage similar situations, promoting healthier outcomes.

What is Haemophilus influenzae?

Protective maternal sphere symbolizing placental health.

Haemophilus influenzae (HI) is a diverse group of bacteria that require specific growth factors, namely factor V (NAD) and factor X (hemin). These bacteria are classified into six capsular serotypes (a-f), with type b (HIb) being the most notorious. HIb is responsible for severe infections, including epiglottitis (inflammation of the epiglottis, which can obstruct the airway), otitis media (middle ear infection), and exacerbations of chronic obstructive pulmonary disease (COPD) in adults.

Thanks to widespread conjugated vaccination, HIb-induced meningitis has significantly decreased in young children. However, many HI strains lack a capsule and are termed non-typable Haemophilus influenzae (NTHI). These strains are not targeted by the HIb vaccine and are increasingly recognized as causes of opportunistic respiratory tract infections. NTHI forms part of the normal flora in the human body, but they can become pathogenic under certain conditions.

  • HIb (Type b): Most dangerous, vaccine preventable.
  • NTHI (Non-typable Haemophilus influenzae): Normal flora, opportunistic infections.
The case reported by Khan and Naab involved an NTHI infection, highlighting the importance of considering non-typable strains in placental infections. Understanding the distinction between HIb and NTHI is essential for appropriate diagnosis and treatment strategies.

Moving Forward: Vigilance and Awareness

The rare case of Haemophilus influenzae placental infection serves as a reminder of the complexities of maternal and neonatal health. While such infections are uncommon, they can have devastating consequences. By increasing awareness, improving diagnostic techniques, and implementing appropriate treatment strategies, healthcare providers can better protect the health of mothers and newborns. The use of chocolate-based agar for culturing specimens, as highlighted in the study, may prove to be a valuable tool in identifying fastidious organisms like Haemophilus influenzae, leading to earlier diagnosis and intervention.

About this Article -

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Everything You Need To Know

1

What is *Haemophilus influenzae* (HI), and what are the main types?

*Haemophilus influenzae* (HI) is a type of bacteria that needs specific growth factors to survive. There are different types, including those with a capsule (like HIb) and those without (NTHI). HIb used to cause serious infections like epiglottitis and meningitis, but vaccines have made these less common. NTHI strains are becoming more recognized as causes of opportunistic infections, especially in the respiratory tract, because they are not targeted by the HIb vaccine. This distinction is important for correct diagnosis and treatment. The case in the study involved an NTHI infection.

2

Why is it important to distinguish between HIb and NTHI strains of *Haemophilus influenzae*?

The distinction between HIb and NTHI strains of *Haemophilus influenzae* is significant because HIb is vaccine-preventable and historically caused severe invasive diseases like meningitis, especially in children. The widespread use of the HIb vaccine has dramatically reduced these infections. However, NTHI strains, which lack a capsule, are not targeted by the HIb vaccine and are increasingly recognized as causes of opportunistic infections. Therefore, awareness and vigilance are required to identify NTHI infections, especially in vulnerable populations like pregnant women and newborns.

3

How is *Haemophilus influenzae* diagnosed in the context of placental infections?

In the context of placental infections, *Haemophilus influenzae* is diagnosed using advanced diagnostic methods, including culturing specimens on chocolate-based agar. This special medium helps identify fastidious organisms like HI, allowing for earlier diagnosis and intervention. Identifying the specific type of HI (HIb or NTHI) is essential for guiding treatment strategies. Early and accurate diagnosis is critical to prevent severe complications such as preterm delivery and stillbirth.

4

What are the potential consequences of placental infections caused by *Haemophilus influenzae*?

Placental infections caused by *Haemophilus influenzae* can lead to preterm deliveries and other complications. In the reported case, the infection resulted in a stillborn male fetus delivered prematurely. This outcome highlights the importance of vigilance and advanced diagnostics in identifying and treating such infections to improve outcomes for both the mother and the newborn. The implications of such infections extend to potential long-term health issues for both mother and child, emphasizing the need for preventive measures and timely intervention.

5

What can be done to promote awareness and prevention of *Haemophilus influenzae* infections during pregnancy?

To promote awareness and prevention, it's crucial to understand that while *Haemophilus influenzae* placental infections are rare, they can have devastating consequences. Healthcare providers can improve outcomes by increasing awareness, utilizing appropriate diagnostic techniques (like chocolate-based agar for culturing), and implementing effective treatment strategies. Parents should be educated about the potential risks of infections during pregnancy and the importance of seeking prompt medical attention if any symptoms arise. Although not specifically discussed, maintaining good hygiene and prenatal care are crucial preventive measures.

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