Severe anemia from bedbugs

A 60-year-old man presented to his family physician with a 2-month history of fatigue and lethargy. Upon questioning, he reported no bleeding from his gastrointestinal tract or other sites. The patient had type 2 diabetes, hypercholesterolemia, reflux esophagitis and depression. His medications were metformin, glyburide, omeprazole, pravastatin, citalopram and olanzapine. He was not taking acetylsalicylic acid or nonsteroidal anti-inflammatory drugs.

The patient had a history of alcohol abuse but had not been drinking for the past year. He used crack cocaine frequently and reported that he often skipped meals while taking crack cocaine. He had no history of cognitive impairment. He lived alone, in an apartment building that had bedbug infestations. He reported a proliferation of bedbugs in his apartment beginning about 2 months before presentation.

On examination, the patient’s skin showed no visible signs of bleeding. There were numerous erythematous, excoriated papules and welts on his scalp and arms. Physical examination was otherwise unremarkable. Laboratory testing showed a hemoglobin level of 80 (normal 135–180) g/L, a mean corpuscular volume of 97.5 (normal 80–97) fL and nonspecific erythrocyte changes on the blood smear. The leukocyte count and differential were normal; the platelet count was 428 (normal 150–400) × 10⁹/L. The serum ferritin level was 18 (normal 27–220) μg/L. Vitamin B₁₂, erythrocyte folate, creatinine and thyroid-stimulating hormone levels were normal. Four months earlier, the patient’s hemoglobin level had been 147 g/L.

Therapy was started with ferrous fumarate, 300 mg orally twice daily, and folic acid, 5 mg orally once daily. The patient was given a single dose of 1000 μg of vitamin B₁₂ intramuscularly. Four weeks later, he was seen again by his family physician and noted to be very pale. He again reported no bleeding. He was admitted to hospital, where his hemoglobin level was found to have dropped to 57 g/L. The reticulocyte count was 5.3% (2.0% after correction for hemoglobin level). Serum lactate dehydrogenase and total bilirubin levels were normal. After the patient received 2 units of red blood cells, his hemoglobin level rose to 77 g/L. No abnormalities of the upper and lower gastrointestinal tracts were seen on gastroscopy and colonoscopy. The patient was discharged home and instructed to continue the oral ferrous fumarate therapy.

Three weeks later, the patient’s hemoglobin level was 52 g/L. He was readmitted to hospital and given 3 units of red blood cells. His hemoglobin level increased to 83 g/L. A computerized tomography scan of the abdomen and pelvis appeared normal. The patient was discharged home with the diagnosis of iron-deficiency anemia of unknown cause.

Shortly after discharge, the patient’s family physician conducted a home visit with the patient. The patient reported that he had hundreds of bedbugs in his apartment but had not made efforts to have the infestation treated. His family physician noted several bedbugs crawling on the patient. Inspection of the apartment revealed dozens of bedbugs crawling on the walls and thousands living within the patient’s mattress and bedding. The physician hypothesized that the patient’s anemia was due to blood loss from bedbug bites. Because the patient lacked the capability to prepare his apartment for treatment of the infestation, public health authorities found temporary accommodation for him at a shelter. His apartment was treated with insecticides by a pest control operator, and all infested furniture was removed.

The patient continued to take 300 mg of ferrous fumarate orally 3 times daily. Four weeks after treatment of his apartment, the patient’s hemoglobin level was 132 g/L. Six weeks later, his hemoglobin level was 146 g/L and his serum ferritin level was normal, at 57 μg/L. Testing of stool specimens for occult blood was negative on 3 occasions.

At 6 months after treatment of his apartment, the patient’s anemia had not recurred. His hemoglobin level has ranged from 139 to 157 g/L. He has reported seeing and killing a few bedbugs in his apartment on a daily basis, but he has not experienced new bedbug bites.

Key points

• Bites from bedbugs often cause a rash consisting of small clusters of pruritic, erythematous papules or wheals.

• A definitive diagnosis of bedbug bites is based on demonstrating the presence of the insect, which may require an inspection of the patient’s home.

• Bedbug bites should be considered a possible cause of iron-deficiency anemia in people who have signs of severe bedbug infestation.

• People with substance abuse, mental illness or cognitive impairment may be at increased risk of severe bedbug infestation.