A 51 year old patient presented to the emergency room with abdominal pain and fever. Fever was associated with diaphoresis, chills and headaches. Patient was in Tanzania for 3 months. She was admitted to the hospital while she was there for some unknown infection, details of which are not available.
CBC done revealed normocytic normochromic anemia with a hemoglobin of 9.2 g/dl and thrombocytopenia. Platelet count was 100 K/uL. On review of peripheral blood revealed presence of malarial parasite (ring forms).
Malaria is an infectious disease caused by Plasmodium parasites. These parasites are primarily spread by the bite of infected female Anopheles mosquitos. There are four main types of Plasmodium (P) species that infect humans:
Plasmodium vivax and Plasmodium ovale, which cause a relapsing form of the disease, and
Plasmodium malariae and Plasmodium falciparum, which do not cause relapses.
Malaria must be recognized promptly in order to treat the patient in time.
Microscopy (morphologic analysis) continues to be the “gold standard” for malaria diagnosis. Parasites may be visualized on both thick and thin blood smears stained with Giemsa, Wright, or Wright-Giemsa stains. Giemsa is the preferred stain, as it allows for detection of certain morphologic features (e.g. Schüffner’s dots, Maurer’s clefts, etc.) that may not be seen with the other two. Ideally, the thick smears are used to detect the presence of parasites while the thin smears are used for species-level identification. Quantification may be done on both thick and thin smears.
Various antigen kits are available to detect antigens derived from malarial parasites. These rapid diagnostic tests (RDT) offer a useful alternative to microscopy in situations where reliable microscopic diagnosis is not available.
-Neerja Vajpayee, MD, is the director of Clinical Pathology at Oneida Health Center in Oneida, New York and is actively involved in signing out surgical pathology and cytology cases in a community setting. Previously, she was on the faculty at SUNY Upstate for several years ( 2002-2016) where she was involved in diagnostic work and medical student/resident teaching.
A 62 year old Caucasian male was referred to the gastroenterology clinic with complaints of epigastric pain, diarrhea and unintentional weight loss over the past couple of weeks. Travel history was significant for a recent mission trip to rural areas of the Philippines. During his time there, he participated in building chicken coops and scuba diving. He reported he mostly ate pork & vegetables but did note he consumed a “runny, undercooked duck egg.” He did not eat any seafood during the trip. About a month after his return, he developed epigastric pain and clinically significant diarrhea, with anywhere from 2-8 bowel movements per day. Testing for blood counts, hepatitis and HIV was performed and stool was collected for culture and ova & parasite exam (O&P). He also underwent a colonoscopy with multiple biopsies.
CBC revealed a white blood cell count of 17.9 TH/cm2 with 63.5% eosinophils. Acute hepatitis panel and HIV screen were negative as were two sets of stool cultures and O&Ps. Colonoscopy showed multiple helminths at the ileo-cecal junction (Image 1) and histology of the worms revealed architecture and eggs consistent with Trichuris trichiura (Images 2 & 3).
Trichuris trichiura is classified as a nematode (roundworm) and is the third most common round worm causing disease in humans. It has a worldwide distribution and infections are most frequent in areas with tropical climates and resource poor settings with inadequate sanitation practices, especially among children. It is estimated that 800 million people are infected worldwide. While most cases diagnosed in the United States occur in immigrants, travelers and military personnel, T. trichiura has also been documented in the southern United States. Clinical presentations are most frequently asymptomatic or mild. Heavy infections, especially in small children, can cause gastrointestinal problems (abdominal pain, diarrhea, rectal prolapse) and possibly growth retardation due to prolonged malnutrition and anemia.
Infection occurs when embryonated eggs are orally ingested with soil contaminated food & water or due to poor hygiene practices. T. trichiura larvae are released in the small intestine and then travel to the colon where they develop into adult forms. Females begin to produce large volumes of eggs (up to 20,000 per day) about 2-3 months after initial infection. Unembryonated eggs are passed in the stool and in warm, moist soil conditions become infective in 15-30 days.
In the laboratory, diagnosis of T. trichiura is most commonly made by identification of the barrel shaped egg with mucous plugs at either end. The eggs have a double shell and are approximately 50-55 um in length. For increased sensitivity, it is recommended that multiple stool specimens for O&P be collected over the course of 7-10 days as shedding is sporadic. Occasionally, adult worms are visualized on colonoscopy and have a long, thin anterior end which attaches to the mucosa and a thicker posterior portion giving the worm a “whip” like appearance. Adult worms typically measure between 3 to 5 cm in length.
Whipworm infections are routinely treated with albendazole or mebendazole. In the case of our patient, he received multiple doses of albendazole and responded well with resolution of symptoms.
-Joy King, MD, is a fourth year Anatomic and Clinical Pathology resident at the University of Mississippi Medical Center.
-Lisa Stempak, MD, is an Assistant Professor of Pathology at the University of Mississippi Medical Center in Jackson, MS. She is certified by the American Board of Pathology in Anatomic and Clinical Pathology as well as Medical Microbiology. Currently, she oversees testing performed in both the Chemistry and Microbiology Laboratories. Her interests include infectious disease histology, process and quality improvement and resident education.
A 19 year old African American male presented to the emergency department (ED) with complaints of fevers, chills, nausea, vomiting, a “head-splitting” headache and abdominal pain. He reported that his fevers and chills had increased in severity, reaching a max of 104°F, and had 7-8 episodes of non-bloody emesis on the day of presentation. Travel history was significant for a recent return from a two year visit to his home country of Ghana. He did state he was bitten by mosquitos there about a week before his symptoms began. In the ED, vital signs showed a fever of 102.6°F, increased respirations (36 per minute) and a normal pulse and blood pressure (98 beats per minute and 120/65, respectively). Initial CBC showed a hemoglobin of 13.2 g/dL and a hematocrit of 37.3%. Platelet count was decreased (31,000 TH/cm2). A malaria screen was ordered to look for the presence of blood parasites.
The BinaxNOW rapid malaria screening test was positive for both P. falciparum and common malarial antigens, making a possible mixed infection unable to be ruled out (Image 1). The thin blood smear revealed numerous trophozoites with multiple ring forms in one red blood cell and appliqué forms, findings characteristic of P. falciparum (Image 2). No advanced forms, including schizonts and gametocytes, were identified. The high level of parasitemia (approximately 5.5%) also supported the diagnosis of P. falciparum.
Malaria is a disease infecting humans through the bite of the female Anopheles mosquito and affects many worldwide, particularly in the tropic and subtropic regions of Africa and Southeast Asia. According to the Centers for Disease Control and Prevention (CDC), an estimated 212 million cases of malaria occurred in 2015 with 429,000 deaths attributed to malaria. In the United States, the majority of cases are diagnosed in travelers and immigrants returning from endemic areas. Rapid diagnosis of malaria, especially in the most aggressive Plasmodium falciparum species, is of utmost importance in order to provide prompt treatment to the patient to minimize morbidity and mortality. Clinical findings can be non-specific, especially early in the disease course, and it is important to ask about travel and exposure history. In the case of P. falciparum, cyclic tertian fevers, chills, headache, nausea, vomiting and muscle aches are common.
Definitive diagnosis is achieved by examination of thick and thin blood smears in the clinical laboratory. These two Giemsa stained smears are prepared in order to recognize the Plasmodium organisms (thick smear) and identify the particular species causing infection (thin smear). This approach remains the gold standard for laboratory confirmation of malaria. In the case of P. falciparum, the most common microscopic findings include visualizing early intracellular trophozoites (two chromatin dots connected by a thin cytoplasm). Multiple rings in a single red cell and appliqué forms (trophozoites at the edge of the red cell) are common as well. The crescent shaped gametocyte is also a diagnostic form of P. falciparum, with schizonts being rare in peripheral blood smears.
Immunochromatographic testing is gaining popularity due to their ability to rapidly (10-15 minutes) detect malaria antigens. This makes them a useful alternative to microscopy where resources do not allow for adequate microscopic examination or trained staff is unavailable around the clock. Although these tests are useful in some clinical settings, cost, accuracy and overall performance need to be considered prior to implementation.
Following identification, another important aspect of the laboratory diagnosis is determining the level of parasitemia, as this aids in the classification of disease severity and how anti-malarial drugs should be administered and in what setting. This determined by the following equation using the thin smear: (number of infected RBCs/total number of RBCs) x 100. At least 500 RBCs should be counted, but in the case of lower levels of parasitemia upwards of 2,000 cells is recommended for the most accurate percentage. Other important points include that gametocytes should not be included in the count and red cells infected with more than one trophozoite should be counted as one infected cell.
In the case of our patient, his parasitemia level of approximately 5.5% classified him as a severe malaria infection and he was transferred to the intensive care unit for close monitoring and treatment with IV quinidine, as this drug is associated with hypoglycemia and QT prolongation. After 24 hours, his parasitemia level was 2.6% but due to significant prolongation of the QT interval on EKG from 407 ms to 560 ms, he was switched to oral atovaquone-proguanil (malarone) after consultation with experts at the CDC. Parasitemia level was 0.4% after an additional 24 hours. The patient was discharged home after completion of therapy and was well at follow up outpatient visit.
-Eric Tillotson, MD, is a second year Anatomic and Clinical Pathology resident at the University of Mississippi Medical Center.
-Lisa Stempak, MD, is an Assistant Professor of Pathology at the University of Mississippi Medical Center in Jackson, MS. She is certified by the American Board of Pathology in Anatomic and Clinical Pathology as well as Medical Microbiology. She is the director of the Microbiology and Serology Laboratories. Her interests include infectious disease histology, process and quality improvement and resident education.
A twenty-four year-old male Kenyan refugee had been in the United States for about a month when he received a mandatory health screen for infectious diseases. He had no complaints and stated that overall, he was generally healthy. Physical exam was significant only for bilateral red conjunctiva. He stated at times his eyes get irritated and have since birth. As part of routine work-up, an ova and parasite stool exam was ordered. Organisms were detected as seen in Image 1.
The patient’s stool examination showed Giardia cysts. Two nuclei are visible in the figure above with centrally located karyosomes. Also visible are the intracytoplasmic fibrils, seen as a darker purple area.
Giardia is a flagellated protozoan that causes giardiasis, a diarrheal illness. It is the most commonly diagnosed intestinal parasitic disease in the United States. It is known as Giardia intestinalis, Giardia lamblia, or Giardia duodenalis. The most common mode of transmission is drinking water contaminated with feces from infected mammals (1).
Symptoms vary and can last 1 week to years if untreated (2). Typical symptoms of giardia are “greasy, foul-smelling, frothy stools that float.” Interestingly, less common symptoms can be itchy skin, hives, eye and joint swelling (3). Retinal arteritis and iridocyclitis has been noted as well (4). It is possible that this patient’s eye irritation is due to a chronic giardiasis infection. Common treatment is usually with an antibiotic/antiparasitic drug like metronidazole (Flagyl).
Diagnosis of Giardia can be made by demonstrating the pear shaped trophozoites and/or ovoid cysts in feces. A key identifier for this parasite is the presence of the two to four nuclei with a central karyosome and intracytoplasmic fibrils that make the parasite look like a face under the microscope. However, because Giardia is excreted intermittently, it is recommended to sample three stool specimens on separate days (5). Due to problems in concentrating the organism for identification on a trichrome stain, a fecal immunoassay is available that is more sensitive and specific (5).
An 8-year-old female presented to an outside hospital with appendicitis-like clinical symptoms and underwent a laparoscopic appendectomy. Gross examination of the appendix (7.2 cm in length x 0.5 cm in diameter) wall was unremarkable and the lumen contained a minimal amount of hemorrhage. The specimen was entirely submitted for microscopic evaluation.
Image 1. Cross section of appendix containing two intra-luminal helminths (H & E stain).
Image 2. Cross section of female Enterobius vermicularis containing eggs (H & E stain).
Image 3. Cross section of male Enterobius vermicularis (H & E stain).
Enterobius vermicularis (human pinworm) is an intestinal nematode (roundworm) with a worldwide distribution that is most prevalent among school-age children. Cross sections of the nonsegmented, cylindrical worms demonstrate a well-developed digestive tract, reproductive system, and two lateral alae (Images 1-3). E. vermicularis has two sexes and Image 1 demonstrates that the male is smaller than the female. Humans are directly infected upon ingestion of E. vermicularis eggs (fecal-oral route of transmission). The eggs then hatch and immature worms undergo maturation within the human gastrointestinal tract (Image 1). Eggs are shed in stool and the typical E. vermicularis eggs (Image 2) are thick-shelled with one flattened aspect, described as “D-shaped”. Patients with the infection are commonly asymptomatic or may complain of perianal pruritus. Rarely, patients present with abdominal pain secondary to E. vermicularis-associated acute appendicitis (1).
Arca MJ, Gates RL, Groner JI, Hammond S, Caniano DA. 2004. Clinical manifestations of appendiceal pinworms in children: an institutional experience and a review of the literature. Pediatr Surg Int 20(5):372-5.
-Adina Bodolan, MD is a 1st year anatomic and clinical pathology resident at the University of Vermont Medical Center.
-Christi Wojewoda, MD, is the Director of Clinical Microbiology at the University of Vermont Medical Center and an Associate Professor at the University of Vermont.
A 20 month old male presented to an outside hospital with symptoms unknown to our laboratory. That laboratory sent us the specimen recovered from a diaper (Image 1).
The nematode Ascaris lumbricoides is one of the most common helminth infections in the United States. It can grow to be 20-35 cm long. Infection occurs when an egg is ingested, usually in a small child eating dirt contaminated with human feces. When the larvae hatch they penetrate the duodenal wall. From there, the larvae go into the blood stream and eventually end up in the pulmonary circulation where the larvae grow in the alveoli. In about three weeks, the larvae are coughed up from the lungs and swallowed. The worms then mature in the jejunum (primarily). Infection most often shows no symptomatology. If symptoms are present, they can range from mild abdominal discomfort to intestinal blockage and even cough as the worms migrate to the lungs .
Diagnosis can be made by examining concentrated stool for knobby-coated, bile-stained eggs that are oval . However, some of the adult worms can pass with the feces.
An 18 year old girl presents to her pediatrician with her mother for her pre-college check-up. She has no past medical history. After her mother leaves the room for the social history component, the girl admits to having sex with her boyfriend for the first time two weeks ago and complains of a yellow green malodorous vaginal discharge that started a week ago. She endorses mild pelvic pain. A pelvic exam is performed and mild cervical tenderness is noted. The cervix is pink, nulliparous, inflamed and is covered by small red punctate spots. A thin yellow green frothy discharge of fishy odor is also detected. A wet prep is made and reveals squamous cells and numerous motile organisms.
Our patient was diagnosed with Trichomonas vaginalis (TV). TV is a flagellated parasitic protozoan for which humans are the only known host. It is 10-20 um long and 2-14 um wide with multiple flagella projecting from the anterior and posterior sides. It has a single trophozoite stage and does not survive well outside of its host. TV is a predatory obligate parasite that eats bacteria, vaginal epithelial cells, and red blood cells. It uses fermentative metabolism to produce the carbohydrates needed for fuel. TV is a sexually transmitted disease; however, because it is not reportable to local health departments, the true epidemiologic incidence rate is unknown. Its prevalence is highly variable by population and location. For example, some studies cite a prevalence of 3.1% of American pre-menopausal women (2.3% of adolescents) , while in certain high-risk populations the rate might be as high as 47% . Most affected patients are asymptomatic; about a third of females become symptomatic within six months of infection. Symptoms for females include vulvar and vaginal irritation and itching, pain with urination and a diffuse, malodorous, yellow-green vaginal discharge. The cervix becomes reddened in a punctuated fashion causing the well-known strawberry cervix seen on colposcopy. In males, urethritis can develop. TV is often diagnosed via wet mount microscopy, where the protozoa can be seen moving around (Video 1). However, the sensitivity is relatively low, especially among males. Detection by nucleic acid probe from urine, endocervical, and vaginal swabs are considered more sensitive. TV can also be incidentally discovered on Pap tests (Figures 1 and 2). Treatment typically consists of a single dose of metronidazole [1,2]. It is critical that partners be treated as well, because otherwise reinfection may occur.
Kissinger P. Trichomonas vaginalis: a review of epidemiologic, clinical and treatment issues. BMC Infectious Diseases. 2015; 15(307): 1-8.
Meites E et al. A review of evidence-based care of symptomatic trichomoniasis and asymptomatic Trichomonas vaginalis infections. Clinical Infectious Diseases. 2015; 61(S8): S837-48.
-Amanda Strickland, MD, is a 2nd year Anatomic and Clinical Pathology Resident at UT Southwestern Medical Center.
–Erin McElvania TeKippe, PhD, D(ABMM), is the Director of Clinical Microbiology at Children’s Medical Center in Dallas Texas and an Assistant Professor of Pathology and Pediatrics at University of Texas Southwestern Medical Center.