Which infection causes low hemoglobin? An expert guide

September 24, 2025 •

3 min read

Anemia is a major global health concern, and infections are a leading cause, particularly in developing regions. Understanding which infection causes low hemoglobin is crucial for effective diagnosis and treatment, as different pathogens affect red blood cell counts through distinct mechanisms.

Quick Summary

Many infections, including parasitic diseases like malaria and hookworm, viral illnesses such as HIV and parvovirus B19, and bacterial infections like sepsis, can lead to low hemoglobin by damaging red blood cells, suppressing bone marrow, or triggering chronic inflammation.

Key Points

Malaria Causes Anemia via Hemolysis: The Plasmodium parasite multiplies inside and ruptures red blood cells, leading to severe hemolytic anemia.
Parvovirus B19 Suppresses Marrow: This virus directly attacks erythroid precursor cells in the bone marrow, halting red blood cell production.
Sepsis Triggers Inflammation: The systemic inflammation from sepsis causes red blood cell destruction and can suppress bone marrow function, contributing to anemia.
Hookworms Cause Iron-Deficiency: These parasitic worms feed on blood in the intestines, causing chronic blood loss that leads to iron-deficiency anemia over time.
Chronic Infections Alter Iron Metabolism: Long-term infections like HIV and tuberculosis trigger anemia of chronic inflammation by trapping iron and suppressing red blood cell formation.
Diagnosis Guides Treatment: Effective treatment requires identifying the specific infection and addressing its underlying mechanism, which may include medication, transfusions, or supplements.

The Multifaceted Link Between Infections and Low Hemoglobin

Infections can lead to a drop in hemoglobin, the protein in red blood cells that carries oxygen, through several different pathways. The resulting condition, known as anemia, is often a secondary effect of the body's immune response or the pathogen's direct attack on the blood system. The specific mechanism depends largely on the type of infectious agent, be it a virus, bacteria, or parasite.

Key Mechanisms of Infection-Induced Anemia

Infections can cause low hemoglobin through several biological processes. These include the direct destruction of red blood cells (hemolysis), suppression of bone marrow function which reduces red blood cell production, and the anemia of chronic inflammation where persistent infection alters iron use. Some infections also cause nutrient deficiencies or trigger immune responses that mistakenly attack red blood cells.

Specific Infections That Cause Low Hemoglobin

Parasitic Infections

Malaria causes profound anemia by the Plasmodium parasite infecting and destroying red blood cells. Hookworm infections cause chronic blood loss in the gut, leading to iron-deficiency anemia. Babesiosis also targets red blood cells, causing hemolytic anemia.

Viral Infections

Human Immunodeficiency Virus (HIV) leads to anemia through bone marrow suppression, increased red blood cell destruction, and chronic inflammation. Parvovirus B19 specifically inhibits red blood cell production in the bone marrow, potentially causing a severe drop in hemoglobin. Other viruses like Hepatitis A and C are also associated with anemia.

Bacterial Infections

Sepsis, a severe systemic infection response, can rapidly decrease hemoglobin due to inflammation, red blood cell destruction, and bone marrow suppression. Chronic bacterial infections like tuberculosis can cause anemia of chronic inflammation. Toxin-producing bacteria, such as Clostridium perfringens, can cause massive red blood cell destruction.

Comparison of Anemia-Causing Infections


Feature	Malaria	Parvovirus B19	Hookworm Infection	Sepsis	Chronic HIV/TB
Primary Mechanism	Hemolysis, Bone Marrow Dysfunction	Bone Marrow Suppression (Erythroid progenitors)	Chronic Blood Loss (Intestinal)	Chronic Inflammation, Hemolysis	Chronic Inflammation, Bone Marrow Suppression
Onset	Acute and Rapid	Acute (can be severe in those with pre-existing conditions)	Gradual and Chronic	Acute and Rapid	Gradual and Chronic
Severity	Can be life-threatening	Often mild but severe in vulnerable groups	Can lead to severe iron-deficiency anemia	Often severe, life-threatening	Varies, can worsen with disease progression
Treatment Focus	Anti-malarial drugs	Supportive care; transfusions if severe	Anti-helminthic drugs, iron supplements	Treating underlying infection, supportive care	Antiretroviral therapy, addressing inflammation

Diagnosis and Management

Diagnosing the cause of anemia involves a comprehensive approach, including medical history, physical examination, and laboratory tests like a complete blood count, iron studies, and specific tests for infectious agents. Management focuses on treating the underlying infection with appropriate medication. Supportive care, such as blood transfusions, may be necessary for severe anemia. Iron supplementation can help in cases of iron deficiency.

For more detailed information on anemia, you can refer to the World Health Organization (WHO) fact sheet on the topic.

Conclusion

Low hemoglobin caused by infection is complex and depends on the specific pathogen and the body's response. From malaria's red blood cell destruction to chronic inflammation in HIV, identifying the cause is key to effective treatment. With proper diagnosis and management, this type of anemia is often reversible.

Frequently Asked Questions

Sepsis triggers a severe inflammatory response, or 'cytokine storm,' which can damage red blood cells, increase their destruction, and suppress the bone marrow's ability to produce new ones. The resulting anemia can be a critical factor in a patient's outcome.

Yes, HIV can cause anemia through several mechanisms, including suppression of the bone marrow, increased destruction of red blood cells, and the anemia of chronic disease. Some older HIV medications also contributed to this, though newer ones have less impact.

In many cases, yes. Once the underlying infection is successfully treated, the body can recover and resume normal red blood cell production. The time for recovery depends on the specific infection and how quickly it was addressed.

Hemolytic anemia, where red blood cells are destroyed prematurely, can be caused by infections like malaria and babesiosis. Some bacterial infections can also release toxins that cause hemolysis.

Yes. Parasitic infections, such as hookworm, can cause chronic intestinal bleeding. This slow, persistent blood loss depletes the body's iron stores, leading to iron-deficiency anemia.

Yes. While both result in low hemoglobin, anemia of chronic inflammation is caused by the body's inflammatory response trapping iron in storage cells, making it unavailable for red blood cell production. Iron-deficiency anemia is caused by a lack of iron in the body, such as from dietary shortage or blood loss.

Diagnosis typically involves a blood test (Complete Blood Count) to check hemoglobin levels, along with tests to identify the specific pathogen. For example, a travel history might prompt a malaria blood smear, or a fever might lead to a blood culture for sepsis.