About wvientos

Microbiologist; Graphic Illustrator

A Small Child is Brought to the Emergency Room Acutely Agitated – Part two

The child in this case study had a cockroach nymph removed from her ear. The infestation of ear canals with various arthropods such as cockroaches, ticks, maggots, etc. is not uncommon and numerous reports are present in the literature. Most of these infestations occur in crowded areas or where the living conditions are conducive to invasion by arthropods.

Some identifications made by readers were that of a bed bug. And this is understandable for various reasons. First, the heavily segmented body of the cockroach nymph can resemble the segmented body of the bed bug. However the shape of the body is not typical of a bed bug. Most bed bugs have a rounder shape to the body and are flat. Though well-fed bedbugs will assume a somewhat elongated body. Cockroaches on the other hand are oval to oval-elongate in shape and are often described as “football shaped”. Unlike the bed bug which has a well exposed head, the head of the cockroach is concealed by a large shield shaped pronotum. The legs of the cockroach are covered with spines while those of the bed bug are not. The antennae of the cockroach are significantly longer than those of the bed bug. Nymph cockroaches have no wings while adult cockroaches generally have wings, and bed bugs have no hind wings with the front wings reduced to leathery pads. That having been said, the cockroach usually will have wings that are either functional or not depending on the species.

While the mouth parts of the bed bug are developed for piercing and sucking, the mouthparts of the cockroach are developed for chewing.

Perhaps the most prominent identifying feature is the presence of two small appendages at the posterior end of the cockroach’s abdomen. These small yet prominent appendages are called “cerci” and are especially prominent in cockroach nymphs. These can be seen in the photograph of the nymph above. Though they can be difficult to see in adults where they are usually covered above by the hind wings.

Infestations in homes and buildings can be extremely difficult to eradicate. The cockroach is extremely resilient and move rapidly, adapting to its environment. Eradication is nearly impossible in one unit of housing if the whole building is not treated and possibly surrounding buildings that are infested. They are mobile and will search out food and new places to dwell. It is an unfortunate consequence of poverty.

On a personal note, I can attest to the psychological effect of an infestation with cockroaches.

When I was young my mother, sister and I had to move into inner city projects. A collection of low income apartments, I can still remember the musty smell that permeated the complex maze of buildings that was our home for at least two years. I remember the weekly violence, the drugs, the hopelessness. But most of all I remember those cockroaches.

They seemed like armies continuously invading our house. Sporadically seen during the day. Seemingly hundreds scurrying around in the darkness of the night. The more we killed the more that seemed to reappear. My sister and I would sleep with fear of them crawling on us in our sleep or worse. Meanwhile my mother who prided herself as being meticulously neat and clean would relentlessly try to rid the apartment of them.

Most disheartening was the memory of my mother’s look of defeat on those days that she felt it was all but hopeless.

When I see a person suffering from an infestation my past brings me to an empathetic understanding of what it is like to be in a position of poverty. Most of these people are just victims of their environment and the social ills that afflict them. If they could, I do not doubt that they would move or rid themselves of the infestation. Many have been fortunate enough in life not to experience and therefore understand the plight of poverty. But I sometimes wonder if it is best to have been unfortunate in life and thereby be able to more easily understand and be empathetic to those around us less unfortunate.

A Small Child is Brought to the Emergency Room Acutely Agitated

A 1-year-old male in severe distress was brought to the emergency room early in the morning by his mother. The mother describes her child as normally mild mannered and happy. He woke her up in the early morning hours screaming and holding his head as if he was experiencing acute pain. She had taken his body temperature and said that it was normal. 

The child was physically examined and there was nothing outwardly abnormal other than his extremely agitated state. His temperature was taken and was found to be normal at 98.6 degrees. Auscultation examination of the chest, abdomen and bowels was normal.

Since the child was not able to verbally communicate where his exact pain was it was important to carefully observe him during the examination in hopes that his actions might provide a clue as to what and where his discomfort was originating from. The key observation noted in the examination was a periodic pulling of his right ear as he would become more agitated. 

An examination of the right ear was significant for the appearance of an object imbedded deep in the ear canal. The doctor proceeded to remove the object carefully and with some difficulty as the object seemed to resist removal. After three attempts the object was finally removed and placed in a sterile sealed cup to be sent to the laboratory for identification. A photo of the object removed was identified as an arthropod by the Microbiology Lab and is shown below. 

Photo of arthropod removed from inner ear of small child

Upon removal of the arthropod the child immediately was relieved of any pain and slowly went to sleep after being fed. The patient was discharged, with instructions provided to the mother, to have her schedule a follow-up with the child’s pediatrician.

Answer the following questions:

  1. What is the identification of the arthropod retrieved?
  2. What are some key identifying characteristics of this arthropod?
  3. What developmental form of the arthropod are we seeing in the image?
  4. Is this arthropod considered a vector of disease(s)?

Guess The Probable Parasitic Diagnosis (Part 2)

This was a case of a chronic Trypanosoma cruzi infection or Chaga’s disease.

The clinical history was significant for immigration from an endemic area in Guatemala and the history of past bites with what she called “vinchucas”. Vinchucas are the local name given to a nocturnal blood feeding Triatomine bug more commonly known as the Raduvid, Kissing or Assassin bug. The Triatomine bug is the known vector of the Trypanosoma cruzi hemoflagellate. Also of note is the past family history of Vinchucas bites, and the illness and early deaths of her brothers in their twenties. The disease due to Trypanosoma cruzi is called Chaga’s disease, named after the Brazilian physician Carlos Chagas who discovered it in 1909.

The patients history and the physical presentation of hepatomegaly with symmetrical distention of the abdomen, and most importantly the abnormal ECG consistent with conduction disturbances, point to a strong suspicion of a case of chronic Trypanosoma cruzi infection.

Trypanosoma cruzi îs one of three pathogenic hemoflagellate. The others being Trypanosoma brucei gambiense (western/Central African Sleeping Sickness) and Trypanosoma brucei rhodesiense (East African sleeping sickness). Trypanosoma cruzi is found predominantly in South America,Central America and Mexico. Besides the geographical difference in distribution, the Trypanosoma gambiense have a different vector in the Tsetse fly (Glossina spp.). With recent border migrations and global warming the incidence of Trypanosoma cruzi has by inching upward geographically into the Southern United States border states. This is especially disconcerting as blood transfusions are a possible mode of transmission.

The disease is most commonly seen in the Central and South American continent, especially in rural areas where the population is poor and live in poorly constructed houses that provide excellent dwellings for the vectors within cracks in the walls. During the day they lay hidden in these cracks only to move out for feeding in the night, attracted to their prey by the detection of CO2. As a result the bites of the nocturnal Triatomine bug are almost exclusively around the facial area. As the Triatomine bug feeds on the blood of the host the bug defecates/urinates. The ensuing allergic reaction to the site of the bite produces itching that introduces the bug’s contaminated feces/urine into the bite site. The feces/urine contains the infective developmental metacyclic trypomastigote form of Trypanosoma cruzi. Lymphadenitis around or under the eyelid (Romana’s Sign) is a result of the host immune reaction to the invading metacylic trypomastigote forms.

Chaga’s disease can present to two forms. An acute and a chronic form. The acute form usually has a duration of two months where there are a high number of parasites circulating in the blood. The acute form can present with a lymphadenopathy around the eyes that is called Romana’s Sign. Other than that, symptoms are either absent or mild in presentation and can run the gamut (headache, fever, muscle pain, shortness of breath, abdominal and chest pain).

It is the chronic phase that is most disconcerting. In this phase the parasite becomes hidden preferentially in the muscles of the heart and digestive tract. The manifestations of the chronic infection may not become apparent for decades where 30% of individuals will suddenly present with cardiac abnormalities and/or 10% will present with digestive abnormalities such as megacolon and/or megaesophagus. Neurological or mixed alterations are possible. Many of these chronic infections will progress to irreversible nervous system damage, difficulty swallowing, digestive problems, heart damage, progressive heart failure and eventual sudden death.

Early treatment of the disease is paramount. It is only in the treatment of the disease in its early stages that cure is possible. Once in the chronic phase, especially in the advanced chronic stage, there is no cure. Therapy is directed at attempting to slow the progression of the disease.

The disease has various ways in which it can be transmitted which is a very important consideration when trying to elucidate the potential for disease in a patient being assessed. The consumption of foods contaminated with the feces/urine of infected Triatomine bugs can be a source of infection. Organ transplants and blood transfusions can be a source of infection. The passage of the parasites to newborn babies is possible. And lastly, though rare, laboratory accidents can be a source of transmission.

As Trypanosoma cruzi continues its upward geographical migration from Central America to the Southern United States, we must increase our vigilance in detecting this disease. The importance of screening for the presence of Trypanosoma cruzi in blood and organs for transplant will need to be incorporated with other already disease screens.

Diagnosis can be made by detecting the trypomastigotes in the peripheral smear as seen below, testing for specific parasite antibodies, and a good clinical history of the patient. Trypomastigotes are not commonly seen in patients with long chronic disease and therefore antibody testing along with a clinical history are going to be diagnostic.

High Oil Immersion photo image of a Trypanosoma cruzi trypomastigote in a peripheral smear preparation. Of note is the large kinetoplast characteristic to T. cruzi. Trypanosoma gambiense spp. do not have a prominent kinetoplast.

Guess The Probable Parasitic Diagnosis (Part 1)

A 24 four-year old woman reports to a physician for a physical examination after experiencing what she describes as chronic fatigue and a vague recurring chest pain. At first glance she appears to be a healthy young woman of average weight for her height. Her English is poor, so much of her history is obtained through an interpreter friend that is accompanying her.

Further questioning reveals that she has had some discomfort to her throat for the last two weeks that she describes as swollen with periods of difficulty swallowing. For the last few months she has also been experiencing occasional dizziness and has had approximately eight fainting spells during that period. She also complained of constipation with abdominal discomfort. 

She immigrated to the United States one month ago from Guatemala where she fled the wide spread violence that had recently increased in that country. When asked about her health history while living in Guatemala she provided nothing of significance. She claimed to have a relatively healthy childhood and early adulthood there. She never had the need to see a physician while she lived there and her illnesses did not require hospitalization or a physician. She did however recollect that as a child “vinchucas” would bite her and her siblings and that it was a constant nuisance for them. She recollected that some of her brothers became very ill soon after being bitten. Once they moved to a better area where their housing improved, the biting stopped altogether.  Her family history was significant for two of her siblings whom had died unexpectedly while in their late twenties. 

Her physical examination was significant for a slightly palpable enlarged liver and an abdomen that is asymmetrically distended. Heart sounds are atypical and an ECG performed in the office-detected abnormalities consistent with conduction disturbances. A referral to a cardiologist was immediately made. 

Based on the clinical history, family history, and clinical presentation the physician has ordered specific tests to rule out an infection with a particular parasite. 

Please answer the following questions:

What parasite does the physician suspect the patient having?

What is a “vinchucas” and what is its significance?

What tests, based on the clinical presentation, should the physician order to confirm an infection with the parasite suspected and why?

What is the suggested treatment for this parasitic infection at this stage?

When Humanity and Disease Intertwine (Part 2)

This is a fatal case of Pneumocystis pneumonia (PCP).

Back when this case showed up in our lab, in 1984, PCP was beginning to become common killer in the HIV/AIDS community. Prior to HIV/AIDS, PCP was rarely seen. Much like other infectious diseases and immunologically related diseases such as Cryptococcal meningitis and Kaposi’s sarcoma, there was a significant uptick related to the HIV/AIDS epidemic. Back in those days PCP was thought to be a protozoan and thus in many parasitic text books it has retained its presence in their pages. Today it is classified as a fungus.

The fungus is ubiquitous in nature. Normal immune systems keep the fungus in check. It is when the immune system becomes compromised as in an HIV/AIDS patient that the organism can establish itself in the host and cause disease. Up to 40% of the cases of PCP are in the HIV/ADIS population. The rest of the cases are distributed in various other disease states that compromise the immune system. Diseases/conditions such as COPD, cancers, immunosuppressive drugs given to reduce the incidence of organ transplant rejection, and any kind of inflammatory autoimmune disease.

The symptoms of PCP usually will develop within a span of several days after being exposed. But there can be some cases where it isn’t for weeks until the symptoms appear. The symptoms include fevers; chest pain; chills; dyspnea; coughing; fatigue.

Most of us are exposed to this fungus and our intact immune system will clear it. 20% of the population may carry it at a time. This population can be a source of spread via droplets to susceptible individuals. Though as previously stated the fungus is ubiquitous in nature and therefore is most likely acquired through environmental exposure.

Diagnosis is usually made by collecting sputum or a bronchioalveolar lavage specimen. The bronchioalveolar lavage specimen is a much more reliable specimen for the detection of the fungus. In highly suspected cases where the above specimens are not acquired as needed then there may be the need to perform a lung tissue biopsy but only as a last resort. Especially when there are highly sensitive PCR tests available. These are not routinely available however and direct fluorescent antibody staining or silver stains are employed instead.

Lung radiographic studies can provide a strong suspicion of PCP given the history of the patient. The most common finding in high resolution CTs is the appearance of a diffuse ground-glass opacity or GGO. This finding is thought to be due to the accumulation of intralveolar fibrin, debris and organisms.

The infection must be treated. PCP can cause death in the vulnerable patient. Indeed, during the HIV/AIDS epidemic the PCP fatality rate was especially high. Today with the advent of fantastic antiretroviral drugs to treat HIV/AIDS, the incidence of many of the diseases such as PCP have dramatically reduced the fatal outcomes of the past. These antiretroviral drugs are critical to maintaining the CD4 cell counts elevated and the viral loads low to non detectable. Effectively keeping the patient relatively immunocompetent. In cases of PCP the drug of choice is trimethoprim/sulfamethoxazole or (TMP/SMX). The drug is most popularly known by its trade names, Bactrim, Septra, and Cotrim. Treatment consists of oral or venous administration of the antibiotic for a period of about 3 weeks. Treatment options are available for patients that are hypersensitive to TMP/SMX. Long term preventative medicine can be beneficial for some HIV/AIDS patients more at risk to PCP due to resistant or refractory infections with the virus.

This case was especially difficult for most of us in the lab who knew the patient personally and professionally. Not one of us had any hint of him being HIV positive. At that time the overwhelming stigma of the disease would have been overwhelming for him to bear. It was early in the HIV/AIDS epidemic. The stigmas had already been deeply perpetrated. The questions to answer would have been too personal in a culture of misunderstanding. In the end he refused to have anyone visit him. Better to be alone than be judged. And that bothered me. Because no one deserves to be alone as they draw their last breaths.


When Humanity and Disease Intertwine (Part 1)

Sometimes we tend to detach ourselves from the reality that diseases can at any time afflict us, the ones we know, or those we love. We place around us an invisible protective shield of denial. The reality is that at any time we can and will have some type of disease process afflict us. Rarely is anyone spared. But armed with knowledge we can limit our chances of acquiring diseases. In the end how we are affected by a disease process will be determined by a multitude of factors. And those factors may ultimately determine whether the outcome of the disease process results in an uneventful recovery, morbidity, or mortality.

When we think about all the advances in healthcare and the knowledge of disease processes that have accumulated over the history of mankind, we have certainly come a long way. Improved sanitary conditions, antibiotics and vaccines have saved millions of lives. In addition, the recognition of risk factors both behavioral and environmental have provided us with the preventative knowledge base that is invaluable in the prevention of disease processes. And yet some diseases are of bad genetic luck. Most of us however have the decision making knowledge to not fall victim.

But alas we are human. Armed with knowledge we still run against what is proven to be true because of whatever reasoning we may have manufactured. We know texting and driving kills, but at any time driving down a highway we can see people texting and driving. We know that vaccines prevent disease, but we fail to immunize because of unfounded fears or listening to the rants of some charlatan calling themselves a doctor. Drugs of abuse destroy and kill, but we in the United States consume more than any other country. We know that unprotected casual sex is a gamble not worth taking, but millions still do. Cigarettes kill yet we still are willing to buy them at exorbitant prices and smoke them. The list goes on and on. Humanity is in away the ultimate paradox.

So, what does this have to do with this particular case study? Many of my past case studies are fictional vignettes while others are real life case studies that I have experienced in whatever laboratory I was working in. What is true about all the cases is that they involve humans that all have strengths and weaknesses that we all have in varying degrees. It’s what makes us all complex and different from one or the other. For better or for worse. This particular case study was a real-life experience, and an unfortunate one at that.

Many years ago, I had taken another job and was working close to 80 hours a week. I would work the first shift in one laboratory and drive a half hour to another and work the second shift. It was, to say the least, absolutely a terrible life schedule. But as I alluded to earlier, we humans tend to not do what is logical or correct sometimes. I had failed in my marriage and was having to pay the piper. Taking responsibility.

I became friends with the laboratory manager within the second week. He would stop in and chat with me and ask how things were going. It wasn’t a very long chat but nevertheless he seemed genuinely interested with the second shift personnel and the workload. I was unaccustomed to having a laboratory manager be as dedicated and concerned as he was.

About two months into the job, I was working one night when a delivery of specimens came in from the emergency room. I started to open and inspect each specimen to match with each requisition when I noticed it was the laboratory managers name on the specimens and requisitions. There were two sets of blood cultures, RSV and Flu tests, and two bronchial aspirates for culture. 

I proceeded to process the blood culture into the blood culture instrument. I performed some rapid testing for RSV and influenza which were both negative. The bronchial specimens were cultured and Gram stains performed. The Gram stains were positive for white blood cells and no epithelial cells however there were no organisms present in significant numbers. It was odd to me that such a purulent and good specimen had no visible presence of organisms.

A physician from the emergency room called later that night requesting that I perform a silver stain on the bronchial specimen. The results of the stain are illustrated in the representative photograph below.

The patient was transferred to the intensive care unit and unfortunately expired on his third day there.

Can you answer the following questions pertaining to this clinical case study?

  1. What is the diagnosis of this patient based on the silver stain result?
  2. What are the predisposing factors to acquiring this parasitic disease?
  3. How is this parasite classified?
  4. What is the standard treatment for this parasitic disease?

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Male Dermacentor variabilis – photo by W. Vientos
PARASITOLOGY WORLD is a website providing educational material and insight into the world of parasitology.

PARASITOLOGY WORLD will periodically post clinical case studies and news pertinent to the field of clinical parasitology.

The increase in travel and the effects of global warming have placed all populations at risk for parasitic infections that would otherwise be unfamiliar to specific geographic areas. Add to this the increasing discovery of new and emerging parasitic infections and one can then appreciate the need for microbiologists and clinicians to maintain a knowledge base that is current.

We will continue to build our website and encourage your input as we grow. Hopefully we can eventually become a site that will be a worthy destination for Microbiologists. Clinicians, and Students.