This week's case is from Idzi Potters and the Institute of Tropical Medicine, Antwerp. It looks somewhat similar to last week's case, but it is very different!
The following objects were seen in a stool specimen from a middle-aged male with recent travel to Senegal.
This week's interesting case was donated by Dr. Karine Thievierge and Alexandra. The following structures were seen in a stool specimen. They measure between 110 - 140 micrometers in length, by 75 - 90 micrometers in width. Identification?
Answer to the Parasite Case of the Week 627: Mite eggs; finding is not of medical concern
Mites and their eggs may occasionally be found in human stool specimens, given that mites are all around us - in dust, on our skin, and in our food! (check out my previous case of the week on Cheese Mites). Although mite eggs resemble those of some human parasites (e.g., the human hookworms), they are usually larger, and there is often evidence of an immature mite inside, as seen in this case:
This week's post is from my own collection - A Giemsa-stained preparation of vaginal secretions from a woman with dyspareunia. The objects measure approximately 15-20 micrometers in maximum dimension.
Identification?
On a related topic, I had the privilege of recording a podcast with Dennis Strenk, the founder and voice of the People of Pathology Podcast. You can listen to our podcast here:
Spotify: https://open.spotify.com/episode/0q2wPe3NdMB4T9YkECP8Y5?si=4AfWDZHqQoS0ph-QZXtiig
Answer to the Parasite Case of the Week 626: Trichomonas vaginalis. The images from this case show the classic morphology of this organism. Here are some of these key diagnostic features:
Although T. vaginalis can be seen in vaginal secretions, male urethral secretions, and in urine, the most sensitive detection method is a nucleic acid amplification test (NAAT). This is what we use in my laboratory. Importantly, the NAAT we use does not cross-react with the other trichomonads found in the oral cavity and intestine.
As Sam mentioned, "Treatment with metronidazole would be appropriate. This would be of concern if the patient was pregnant as T. vaginalis can cause premature rupture of membranes, preterm birth, and decreased birth weights." T. vaginalis can also increase the risk of HIV transmission, so treatment is indicated even if the patient is asymptomatic.
Thanks to all who wrote in with comments!
This week's case was generously donated by Dr. Marijo Roiko, Dr. Shifteh Vahidi, and Ms. Marnie Larsen. Marnie noticed the unusual structure shown in the image below in a urine cytology specimen from an elderly male with a history of hematuria. The structure in the image was observed on PAP stain and was a solitary finding; it measures 125 x 75 µm.
Answer to the Parasite Case of the Week 625: Not a parasite; rotifer
This fascinating "wheel animal" (from Latin rota "wheel" and -fer "bearing") has been seen a couple of times in the past on this blog. Check out our previous cases with great photos and videos:
Case 517 (unstained with video)
Case 304 (another Pap-stained case)
Here are some of the diagnostic features in this case:
This week's case is a bit unusual in that it is an environmental sample (but the parasite has relevance to human health). The following were seen in a soil sample taken from a child's playground. They are approximately 80 micrometers in greatest dimension. Most likely identification?
Answer to the Parasite Case of the Week 624: Toxocara sp. eggs. Note that one is fully embryonated and contains an L3 larva. These eggs are found in the feces of the definitive hosts: T. canis in canids and T. cati in felids. Based on the size, the eggs in this case of likely to be those of T. canis, which is slightly small than the eggs of T. cati (80-85 vs 65-75 microns respectively). Of note, these eggs are NOT found in human feces. However, they are a risk to humans if ingested, since eggs with larvae will hatch and can cause visceral larva migrans. That is why finding eggs in the soil of a child's playground is particularly concerning.
The eggs can be identified by their thick outer shell with a pitted surface. It's a very striking appearance.
You can read more about these fascinating zoonotic parasites on the U.S. Centers for Disease Control and Prevention (CDC) DPDx website. Toxocariasis is identified by the CDC as one of 5 Neglected Parasitic Infections in the United States, and is quite prevalent in many places worldwide.
The following objects were seen on a peripheral blood film from a patient with chronic, worsening swelling in his groin over the past 5 years. He is from Central Africa. The stain is the Delafield's hematoxylin. Diagnosis?
