Viruses and Eukaryotes

Question 1

Adenovirus

Answer 1

dsDNA virus. Naked virus. Most common infection of the adenoids (tissue behind the nasal cavity) and tonsils, thus leading to tonsilitis.

Transmitted via respiratory droplets and fecal-oral route.

Most commonly affects children, those who frequent pools, and army barracks.

Causes hemorrhagic cystitis, which presents with hematouria, viral conjunctivitis, and as mentioned above, tonsilitis.

Live attenuated vaccine available but given mostly to military recruits to prevent eye infections

Question 2

Arenavirus

Answer 2

ssRNA negative sense virus, replicates in the cytoplasm, enveloped.
Unique: it’s ambisense. Helical shaped nucleocapsid, similar to rhabdo and Filovirus.

One of the four segmented BOAR viruses (Bunya, Orthomyxo, arena, reo) and has two segments.

Transmitted via rodents

Lymphocytic choriomeningitis virus (LCV)

Leads to febrile aseptic meningoencephalitis

Inactivated by heat, irradiation.

Sketchy picture: Arena fights (not included in viral screenshot file)

Question 3

Aspergillus fumigatus

Answer 3

Catalase positive fungus (like candida). Peanuts associated with aflatoxins that are produced by Aspergillus flavus, as well as wheat plants. Of interest because aflatoxins are extremely carcinogenic, specifically for hepatocellular carcinoma.

Structurally, the hyphae of Aspergillus have acute branching angles and possess septations between the “squares” of the fungi.

Spread: In fruiting bodies, will form conidiophores on stems, released into the air, and then inhaled by us.

Causes three different infections:

Allergic Bronchopulmonary Asperigillosis

Type I Hypersensitivity reaction that causes wheezing, fever, and migrating pulmonary infiltrates. Will also see increased circulating IgE

Aspergillomas

Solid balls of fungus found in lungs, typically associated with preexisting cavities (ex. from TB or Klebsiella). Be aware that the cavities are gravity dependent, which can affect how they appear on radiography

Angioinvasive aspergillosis

Affects immunocompromised patients, particularly those with neutropenia from leukemia or lymphoma. Invades blood vessels and disseminates very quickly throughout the body. Can be observed on microscopy with the acute angle, septated hyphae invading tissues.

Would see fever, cough, hemoptosis. End stage disease will lead to kidney failure, endocarditis, and ring enhancing brain lesions. Can also spread to paranasal sinuses and cause necrosis around the nose

Treatment

Less serious infections, treat with voriconazole. Aspergilomas aso need to be surgically treated
Angioinvasive disesase will be treated with amphotericin B

Question 4

Babesia (microti/bovis)

Answer 4

Causes babesiosis. Most of the symptoms are blood-related, such as hemolytic anemia, hemoglobinuria, and resulting jaundice. Many people can carry this asymptomatically

Carried by the Ixodes (Deer) tick, and spread via the tick salivations, so coinfection with Borrelia Burgdorferi (sp?) is common

Symptoms: Fever, irregularly cycling fevers, as well as the ones listed above. Higher risk of severe diseases in sickle cell disease, association seems to be due to the fact that asplenic individuals tend to have more severe symptoms and sickle cell patients almost uniformly lack a spleen

Diagnosis: Thick blood cell smear and Maltese cross appearance in RBCs, formed by tetrad of trophozoites and useful for differentiation from malaria

Treatment: Atovaquone and azithromycin (macrolide)

Question 5

Blastomycosis dermatitidis

Answer 5

Dimorphic fungus (mold in the cold, yeast in the heat). Spores can be aerosolized in the soil, and once in our respiratory tract because yeast. Reproduce by budding, however is broad based (size of buds will be similar to size of parent cell)

Blastomycosis are very large and are about the size of RBCs.

Causes blastomycosis, leads to a patchy alveolar infiltrate on X ray (hazyness), potentially lesions or cavity. However, majority infections are subclinical

Systemic infections only seen in immunocompromised. Disseminated infections of blasto target the skin and bone, leading to osteomyelitis

Tend to be found around the Greak Lakes and Ohio River Valley

Diagnosis: KOH stain, urine antigen test

Treatment: local infection, use itraconazole. Systemic infection: amphotericin B

Question 6

Bunyavirus (hantavirus

Answer 6

ssRNA, negative sense, enveloped virus. Unlike other viruses, Bunyavirus obtains its envelop from Golgi complex of host cells. One of the four segmented viruses (BOAR - bunya, orthomyxo, arenavirus, Reovirus), bunyavirus have three segments

Bunyaviruses are mostly arboviruses (arthropod vector)

Hantavirus

Resevoir is a deer mouse and spread via feces and urine.

Symptoms: pulmonary edema via capillary leak and pre-renal azotemia (most common cause of acute renal failure, excess of nitrogen compounds in blood stream due to lack of blood flow to each kidney). Can also cause hemorrhagic fever

Rift Valley/California encephalitis Fever

Causes seizures, encephalitis. Vector carried by the Aedes mosquito

Question 7

Candida albicans

Answer 7

Causes cutaneous and systemic infections. Dimorphic, however in a backwards fashion; forms budding yeast and pseudohyphae in the cold and germ tubes (hyphae) at high temperatures. Is also catalase positive, bear in mind that individuals with chronic granulomatous disease are susceptible to infection

Normal GI flora, so generally see it infecting only in immunocompromised patients. Also keep in mind that since it is present in the oral flora, can contaminate sputum cultures

In children

Diaper rash is a characteristic distribution due to heat and humidity within a baby’s diaper

Oral candidiasis (White pseudomembranes)

Can be seen at any age, but particulary immunocompromised patients or those using oral steroids (such as inhalers, can be avoided by oral rinsing). These white patches can be scraped off (in contrast to leukoplakia, which cannot be scraped off)

It also can descend into the esophagus and cause Candidal esophagitis. This is classical AIDS defining illness and we tend to see it at CD4 less than 100

Treated with nystatin which is used specifically for oral and esophageal candidiasis

Vaginal candidiasis (Candidal vulvovaginitis)

Can be seen in women taking antibiotics (diminish normal flora and allow candida to flourish), diabetics, or those on birth control. Candida does not change vaginal pH

Candidal endocarditis

Commonly seen in drug users because candida can grow in heroin. Because the first valve it would encounter is the tricuspid valve, that is the one it is most likely to infect.

Treatment

Amphotericin B for severe, disseminated infections. Capsofungin can also be used to disseminated infections that are resistant to amphotericin B. Iconazoles for localized infections

Question 8

Cestodes (tapeworms): Tinea solium/saginata, Diphyllobothrium latum, Echinococcus granulosus

Answer 8

Tinea solium/saginata

Saginata is carried in cattle, solium in pigs. T. solium has hooks on their proglottid heads and can be seen on O&P. T. saginata lacks these hooks. Ingestion of the worms simply causes GI involvement.

Can cause neurocysticercosis when people ingest water contaminated with eggs from these species, which causes the parasite to go to the brain and cause cystic brain lesions (looks like Swiss cheese on MRI), which have the potential to cause seizures and hydrocephalus

Treatment: Praziquantel, if neurocysicercosis then additionally treat with albendazole

Diphyllobothrium latum (Fish tapeworm)

Resides in the small bowel and causes diarrhea and is associated with B12 (cobalamine) deficiency, leading to megaloblastic anemia. Largest of the tapeworms and can grow up to 10 meters long

Diagnosis: proglottid segments seen on stool O&P

Treatment: Praziquantel or Niclosamide

Echinococcus granulosus

Dogs are the definitive host, sheep are the intermediate host. Humans are incidental hosts when we ingested things contaminated by dog feces. Will cause eggshell calcifications in cysts within the liver that can be visualized on CT. Shape is that of a hydratid cyst (cysts wall containing hydatid sand, scolices, and brood capsules)

Trouble occurs when the cysts rupture, which can cause an anaphylactic reaction and acute abdomen. In these cases, surgeons will inject ethanol or hypertonic saline to kill these cells before removing the cyst.

Treatment: Surgical removal of the cysts comibined with albendazole

As with all helminths, all these bugs cause eosinophilia

Question 9

Coccidiodes immitis

Answer 9

Common in Califormia and the Southeastern United States

Inhaled as a single spore (arthroconidium) that normally resides in dust, so instances of enhanced dust in the air leads to an increase in infections (earthquakes, etc.)

Dimorphic fungi, however unlike the other systemic fungi, it resides as a spherules of endospores in the lungs, that eventually rupture and spread throughout the body. The spherules are larger than RBCs (recall that histo was smaller and blasto are about the same as RBCs)

Clinical: subclinical in most people, but can present as a self-limited acute pneumonia with fever, sweats, and arthralgias that can last for weeks. On radiographic imaging, may show nothing or may show cavities/nodules. Will also present with erythema nodosum, moreso than histo

Be aware that erythema nodosum is a sign of a robust immune response, so we only really see it in healthy people

Systemic infections are seen in the immunocompromised. Skin and lungs are common sites of infection, as well as dissemination to the bone. Also, can spread to the meninges and cause meningitis

Diagnosis: Hard to diagnose clinically, so usually use KOH stain or culture. Can also send off for serology (similar to other fungi)

Treatment: Local lung infection is treated with conazoles. Systemic infection is treated with amphotericin B

Question 10

Coronavirus (SARS)

Answer 10

Positive sense ssRNA virus, encapsulated (helical shaped, unique to coronavirus). Replicates in cytoplasm (like all +ssRNA)

Can cause common cold, but also cause of SARS, and Middle East Respitaroy Syndrome

Causes: acute bronchitis, and can lead to acute respiratory distress syndrome

Diagnosis: PCR to SARS or antibodies to SARS.
Treatment: variable, but nothing completely works

Question 11

Coxsackievirus

Answer 11

Positive sense ssRNA virus, nonenveloped picornavirus that’s part of the family of enteroviruses. Acid labile, grows at 37C.

CoxsackieA is associated with hand, foot, and mouth disease, causing red vesicular rash (similar to Syphilis and Rickettsia). Causes aseptic meningitis. Occurs most commonly in the summer

CoxsackieB can cause dilated cardiomyopathy and cause Devils grip, otherwise known as Bornholm’s disease or pleurodynia, which is characterized by sharp pain in the chest and is unilateral, making it difficult to breath

Treatment is just supportive

Question 12

Cryptococcus neoformans

Answer 12

Opportunistic fungi that are heavily encapsulated that is made up of repeating polysaccharide capsular antigens (important because it’s one of the main virulence factors for avoiding phagocytes, and is used in the diagnostic test). Also is urease positive

Normally found in the soil, and spread to people via pidgeon droppings. After inhalation, will settle in the lungs as primary focus and then disseminate from there

Since it is an opportunistic infection, it more common affects immunocompromised patients

Pulmonary Symptoms ==> Pneumonia

Can cause cough, dyspnea, and other serios lung infections, but can often remain asymptomatic

Meningitis

Is the most common cause of fungal meningitis as it can spread to the CSF, can lead to permanent neurodeficits and can be lethal.

Fever

Will also present with fever

Diagnostic tests: bronchopulmonary washings of the lung. Tissue samples are then stained with mucicarmine (red) or methanamine silver stains

Diagnosis: Do an LP and stain the CSF with India Ink, which still stain the background dark while leaving the organism transparent. This will show yeast with wide capsular halos.
Better test is latex agglutination test, detects repeating polysaccharide capsular antigen and causes aggluntination
Brain lesions appear on imaging to be “soap bubble” lesions in grey matter

Treatment (for meningitis): Amphotericin B and Flucytosine followed by maintenance therapy using fluconazole

Question 13

Cytomegalovirus (CMV)

Answer 13

Herpes family virus, DNA virus, replicates in host cell nuclei. Like all Herpes viruses, they possess the ability to remain latent. For CMV, it remains latent in mononuclear leukocytes cells (lymphocytes, monocytes, and macrophages). Reactivation occurs by immunosuppression

Transmitted in many different ways (TORCH infection), as well as blood, semen, etc.

Congenital CMV is the most common fetal viral infection, causing blueberry muffin rash (byproduct of thrombocytopenia causing a petichial rash), hepatosplenomegaly, and sensorineural deafness. Can also cause ventriculomegaly, periventricular calcifications, leading to seizures and mental retardation. However, 80-90% of newborns with CMV are asymptomatic. Is the most common congenital viral cause of mental retardation, and top cause of sensorineural hearing loss.

If the mother is CMV positive, can lead to hydrops fetalis. This is associated with the second trimester of pregnancy and causes heart failure with fluid accumulation in multiple compartments, causing spontaneous abortion.

Also seen in transplant patients due to their immunosuppresion (CMV pneumonia), as well as AIDS patients (especially with CD4 below 50). In AIDS patients, their most common presentation is with CMV retinitis, may also present with linear ulcerations in the esophagus (Herpes esophagitis causes multiple shallow ulcerations). CMV colitis also potential threat, would see ulcerated walls of the colon

CMV infected cells will show Owl’s eye inclusion bodies.

For normal people, infection by CMV causes infectious mononucleosis. Would differentiate between CMV and EBV with a monospot test, if negative it’s CMV mononucleosis

Treatment: Ganciclovir primarily, however you’d treat with foscarnet when the virus acquires resistance against ganciclovir via mutations in the UL97 gene

Question 14

Dermatophytes

Answer 14

Fungi responsible for tinea disease, each type of tinea named for the area it affects. Tinea also commonly referred to as ring worm.

Three main dematophytes: Trichophyton, Epidermophyton, and Microsporum. All reside on the skin (name in Greek means “skin plants”). Rarely invade

Types of Tinea

Tinea capitis: Ringworm of the scalp
Tinea corporis: Ringworm on the body (corpris means body in latin)
Tinea cruris: Ringworm on the groin, also referred to as Jock Itch
Tinea pedis: Ringworm of the foot, also referred to as Athlete’s Foot

Lesions are pruritic (itchy)
Commonly passed between athletes (swimmers, wrestlers). Animals can also be a source, especially in kids.

Diagnosis: Typically can be done via clinical presentation and history. Confirm with KOH prep of skin scrapings to reveal hyphae. Can also use Wood’s Lamps to diagnose Microsporum

Treatment: Topical -azoles

Onychomycosis

Dermatophytes can also cause infections underneath the nails (listed above)

Treatment: Oral Terbinafine

For persistent tinea and onychomycosis:

Treatment: Griseofulvin, likes to deposit in keratinocytes, where these things like to hang out. However, has many GI side effects

Question 15

Entamoeba histolytica

Answer 15

Parasite that causes amoebiasis (bloody diarrhea)

Two main life cycle stages: cysts (infectious form), common in men who have sex with men and found to be related to fecal oral transmission. Second part stage they become trophozoites, where they spread through the GI to portal circulation and infect the liver (right lobe most common site of amoebic liver abscess)

Lesions tend to be solitary, but can have multiple abscesses. Leads to RUQ pain and hepatomegaly. Abscesses are described as having anchovy paste consistency

Alternatively, can cause intestina amebiasis, which causes ulceracions in the colon (flasked shaped). Leading to bloody diarrhea. Stool culture will so trophozoites that have endocytosed RBCs and can be seen in their cytoplasm

Treatment: metronidazole. Can also treat with paramycin to target the cysts while in the intestines, or iodoquinol. Keep in mind, you don’t need to surgically treat these abscesses as opposed to other instances (such as echinococcus)

Question 16

Epstein Barr Virus (EBV)

Answer 16

Member of the Herpes virus family. dsDNA virus, enveloped

Causes infectious mononucleosis, transmitted via saliva. Presents with fever, tender LAD on posterior cervical lymph nodes. Hallmark of this disease is reactive CD8 T cells that look typical (Downey Cells) on peripheral blood smear, larger than normal with indented nuclei and large cytoplasm. Presents with splenomegally due to T cell proliferation, may also show hepatomegally though less commonly.

Upon infection, they infect B cells and remain latent there. EBV has envelop glycoprotein that binds CD21, a complement receptor) to infect B cells

Symptoms: pharyngitis, tonsillar exudates (white chunks on back of the throat), fever, posterior cervical LAD, splenomegally. Can be asymptomatic in children, more likely to be symptomatic with age. Needs to be differentiated from strep pharyngitis, which is more likely to infect younger patients. Treatment with amoxicillin or ampicillin (IV counterpart) in patients that have EBV will develop a maculopappilar rash

EBV is also a risk factor for cancers, especially in immunecompromised patients: B cell lymphomas, specifically Hodkin’s Lymphoma Mixed Cellularity subtype and non-Hodkin’s Lymphoma Burkitt’s subtype (either endemic or African, African present with large jaw lesion by parotid gland and swelling, sporadic will develop in ileocecal or inguinal areas), and finally nasopharyngeal carcinoma

Oral-hairy leukoplakia is also seen in HIV patients with the virus, but is a non-cancerous lesion. Lesions will present on the lateral portions of the tongue.

Diagnosed: if infection is active, the antibodies that the infected B cells secrete will cause agglutination of sheep or horse RBCs, which is used for the diagnosis of mono (Monospot test).

Treatment: Mainly supportive therapy, but must avoid contact sports because of splenic rupture as a byproduct of splenomegaly.

Question 17

Filovirus (Ebola)

Answer 17

ssRNA negative sense virus with helical capsid, replicates in cytoplasm, enveloped.

Marburg and Ebola are two viruses that cause similar symptoms

Symptoms begin with flu like symptoms (fever, fatigue, myalgia, GI symptoms) that then progresses to hemorrhagic fever and end-organ failure. Will also show hemorrhagic (hypovolemic) shock

Resevoir is the fruit bat. Contact between humans is via body secretions (feces, blood, semen is particularly dangerous as viral RNA can hang out there for an extended time, infect other people)

Treatment (According to Hatch lecture) are variable in efficacy, ZMapp (monoclonal antibodies against it) and Favipiravir (RNAP inhibitor) have shown some efficacy

Question 18

Flavivirus

Answer 18

Positive sense RNA, enveloped, nonsegmented viruses which includes HepatitisC, Dengue Fever

Flavi refers to the color yellow, indicating these viruses cause jaundice

Dengue: carried via mosquitos (Aedes Egyptei) and infects the bone marrow (break-bone fever) seen in TypeII. With infected bone marrow, patients develop thrombocytopenia, which increases risk of bleeding leading to Hemorrhagic fever, renal failure. Treatment for Dengue fever is only supportive, with hydration therapy

Yellow Fever: Transmitted via mosquitos (Aedes Egyptei). Causes jaundice (hence yellow), bach ache, bloody stool/diarrhea, bloody vomiting. Vaccine does exist for Dengue, which is a live attenuated version

West Nile Virus: Resevoir for virus is birds but will be transmitted via mosquitos as well (Coolecks mosquitos). Major complication with West Nile Virus is Encephalitis, as well as meningitis, and flaccid paralysis. Later complications include seizures and coma. Confirm diagnosis with PCR of CSF. Treatment is simply supportive

Question 19

Giardia lamblia

Answer 19

Parasite associated with hikers and campers and travelers that are traveling somewhere Giardia is endemic and drink contaminated water by human or animal feces. Because of this, it is transmitted fecal-oral route via the cysts

Causes bloating, flatulence, and foul smelling diarrhea (Steatorrhea, otherwise known as fatty diarrhea). The parasites themselves have a ditinct trophozoite shape, which is flaggelated with ventral sucking discs. Attach and doesn’t invade. Finding them in the stool is diagnostic

The test you would run is a stool O&P. Can also do ELISA stool antigen

Treatment: Treat with metronidazole

Question 20

Hepatitis B Virus (HBV)

Answer 20

Part of the hepadnavirus family. Unlike the HepA/C, it is a DNA virus (other ones are RNA viruses). Enveloped.

Unique: replicates inside and outside the nucleus. Genome is circular and partially double stranded, becomes fully double stranded during replication. Goes from partial dsDNA –> ssRNA –> dsDNA due to reverse transcriptase that it carries. Unlike HIV, doesn’t integrateinto the genome.

Spread via needles, intercourse, and can be transmitted vertically during delivery of the baby (too large to cross the placenta) (TORCH)

Symptoms: Hepatitis (less likely than other Hep viruses to become chronic in adults, however newborns with HepB have 90% chance of becoming chronic), polyarteritis nodosa (systemic vasculitis of small or mediaum sized arteries typically involving renal and visceral vessels. Will present with small aneurisms strung together like beads of rosary, so “rosary sign” is important diagnositic feature), glomerulonephritis, rash, athralgia.

Staging: ALT is elevated relative to AST (AST higher in alcoholic hepatitis), rises in acute stage then falls when it subsides, may not go down to normal but will drop. In neonatal hepatitis, ALT will be normal

Serology: Hep B Surface Antigen (HbSAg) is the marker of an active disease, first one measurable. If positive, will have either acute or chronic infection.
HepBe Antigen (HBeAg) comes next, highly correlated with infectivity. If high, the person is highly infectious
The symptomatic portion of the disease is in the beginning of the infection because it takes time to mount immune response
Anti-HBc (HepB core antibody) positive during the window period (period where the antibodies bind the surface antigens)
Anti-HBe antibody to the HepBe antigen
Anti-HBs indicates recovery, no longer has infection acute or chronic. Also seen in vaccinated people, however this individuals will like Anti-HBc and Anti-HBe

Long term sequelae: Associated with cirrhosis and hepatocellular carcinoma, HepD (explained below)

Hepatitis D

RNA negative virus with circulate genome. Require the HbSAg to cause infection. Can occur co-infection or super-infection (when HepD is transmitted on top of existing HepB). Superinfection is more dangerous

Treatment: Acute usually resolves itself, whereas chronic can cause issues. Treat chronic with NRTIs like lamivudine and others, IFN-alpha. Can be given to pregnant women before delivery, and if HepB positive you want to give baby HepB immunoglobulin for active and passive immunity

Question 21

HepatitisA

Answer 21

Positives sense picornavirus, nonenveloped (naked). Is its own family in the picornavirus family. Acid stable, grows at 37C. Transmitted fecal-orally.

In developing countries, it is more of a concern due to its ability to hang out in contanminated water, you need to use chlorination, bleach, UV radiation, or water boiling to inactivate the virus. While we do purify our water, animals caught and eaten from developing countries (such as shellfish) can be contaminated with the virus as well

Can be subclinical, or anicteric meaning without jaundice. But can cause acute hepatitis which would present with fever, jaundice, and hepatomegaly.

Symptoms: Jaundice (esp. in adults, less likely in kids where it will be anicteric), Smokers develop aversion to smoking.

Duration is generally one month and is self-limiting, and there is no carrier state

Vaccine exists for HepA in inactivated form, given to high risk patients such as those traveling/living in endemic areas, chronic liver disease patients, and men that have sex with men

Question 22

HepatitisC

Answer 22

Positive sense RNA virus, enveloped, nonsegmented virus of the flavivirus family.

Most common transmission of the virus is through blood (blood transfusions) and IV drug users (sharing needles), as well as the placenta, breast milk, and sex. HepB is more common through sex, however HepC can also be transmitted via sex

HepC has a great degree of antigenic variability in its enveloped proteins, making it very difficult to vaccinate against. This occurs because the virion encoded RNAP lacks 3’->5’ proofreading, thus mistakes in the viral genome are common, and thus the structure of the virus is also changed commonly.

Causes inflammation of the liver, and in acute stages can cause jaundice. Will see all other markers of liver disease, such as RUQ pain, hepatomegaly, and elevated liver enzymes. Liver cells will either undergo cirrhosis OR, in an effort to replace hepatocytes, the liver will over do it and cause hepatocellular carcinoma (HepC is the primary cause of this). HepC is also associated with cryoglobulins, which are precipitates of IgM antibodies that will be seen at lower temps

In acute infection, ALTs will rise and then fall after 6 months, and we’ll see viral RNA at the start.

In chronic infection, we’ll see persistence of viral RNA

60-80% infections become chronic (C=propensity to become chronic).

Treatment: Ribavirin (drug incorporated into viral RNA and induces mutations in RNA-dependent replication for RNA viruses, hypermutation are lethal to RNA viruses) with INF-alpha. Can also use protease inhibitors to stop processing of polyproteins

Question 23

Herpes Simplex Virus I and II (HSV) (Also complete list of TORCH pathogens)

Answer 23

dsDNA linear Virus part of the Herpes family. Enveloped. Like all DNA viruses, replicates in the nucleus which shows up as Cowdry bodies, which are intranuclear eosinophilic inclusions

Transmitted via sex and saliva, also transmitted vertically (TORCH - Toxoplasmosis (Toxoplasma gondii), “other infections” including Coxsackievirus, varicella zoster virus, Chlamydia, HIV, HTLV, Syphillis, Zika, Rubella, Cytomegalovirus, and Herpes Simplex Virus II

HSV I

Confined to the upper half of the body, causing gingivostomatitis causing inflammation of the lips/mouth. First sign of infection. Becomes Herpes labialis (lip sores/”cold sores”) most common infection of the mouth. Also causes keratoconjunctivitis presenting with serpiginous corneal ulcers on Fluorescein slit lamp exam. Herpes rash has “dew drops on a rose petal” appearance, due to clear vesicles on top of an erythematous base (Ex. Herpetic whitlow on the finger, common in dentists. Caused by both HSV I/II)

Another common manifestation is Erythema multiform 1-2 weeks following infection, which leads to target-like rashes on the backs of hands and feet, then moving back centrally

HSV I is associated with temporal lobe encephalitis, leading to hemorrhage and necrosis of the inferior and medial temporal lobe (most common cause of sporadic encephalitis in USA)

Remains latent in the trigeminal ganglia (CNV)

HSV II

Localized to the genitalia and is transmitted by any action involving the region (sexual or obstetric). Causes Herpes genitalis, which causes painful inguinal LAD with clusters of vesicles with a red base. Can also cause aseptic meningitis in children and adults

HSV II lies dormant in the sacral ganglia

Diagnosis: PCR is the test of choice. Can also use zinc smear (older technique) to look for multinucleated giant cells

Treatment: can cure it, but can use acyclovir or valcyclovir to prevent outbreaks

Question 24

Histoplasma capsulatum

Answer 24

Most fungi will only present clinically in immunocompromised patients

This disease in particular will be associated with bird or bat droppings, or people in places where they could have been exposed. Histoplasma is localized to the central and midwestern United States. Transmission through the respiratory tract usually via inhalation of droppings or spores.

On histology, hallmark is macrophages filled with intracellular oval bodies, stained with a KOH prep. Note: histoplasma is also much smaller than an RBC for comparison. Cultures take very long. Can also use serum/urine rapid antigen tests

Like all systemic fungi, its shape is dimorphic (mold in the cold, yeast in the heat)

Clinical presentation: Generally they are asymptomatic (subclinical) in most people, but in those affected will cause granuloma formation in lungs causing pneumonia. These may eventually calcify, leading to chronic pulmonary issues (similar to TB with cavitary lesions in upper lobes and calcified nodules with fibrotic scarring). Will also present with erythema nodusom, which look like red dots on the lower extremities

In the immunocompromised, will also see hepatosplenomegaly along with calcifications in those places (makes sense they target these places because they target the RES)

Treatment: Local infections or mild infections treated with the -conazoles (fluconazole, etc.). Systemic infections treated with amphotericin B (lots of nasty side effects, so patient must be very sick)

Question 25

Human Immunodeficiency Virus (HIV) - Retrovirus

Answer 25

Positive sense diploid (two strands in each virion) RNA enveloped retrovirus that gets converted into a DNA intermediate by an accompanying reverse transcriptase and inserts itself into host chromosomes, allowing it to replicate forever

Leads to AIDs (acquired immunodeficiency syndrome)

Three major genes it uses are the env, gag, and pol

1) gag = p24, capsule for RNA strands
2) env = glycoprotein 41 (transmembrane protein on the envelope) and 120 (outer glycoprotein that interacts with host receptors), form envelop of the virus
3) pol = reverse transcriptase

Transmission: sexual, vertical (born with it), or blood (IV drug use, etc.). Initially infects macrophages and helper T cells. Enter T cells via either CCR5 (early entry) or CXCR4 (late stages) receptors

Progression: Prodrome consists of flu or mono-like symptoms with cervical lymphadenopathy, fever. Will then enter latent period (can last up to 10 years) where it replicates in lymph nodes until CD4 count drops to below 200, at which point it becomes AIDS. HIV can also cause B cell lymphoma, specifically Diffuse B Cell Lymphoma

Diagnosis: ELISA test for Abs, confirm with Western Blot.

Treatment: Combination therapy always better than monotherapy. NRTIs (Nucleotide Reverse Transcriptase Inhibitors, backbone of retroviral treatment, halts elongation after being inserted into chain), most commonly used one is Zidovudine, commonly used in pregnant patients. NNRTIs (NonNucleotide Reverse Transcriptase Inhibitors), don’t incorporate into chain but has same end result. Protease inhibitors. CCR5 inhibitor (blocks early entry of the virus), commonly used is Maraviroc

Need to do genotyping to figure out correct treatment

Question 26

Intestinal Nematodes: Enterobius vermicularis, Ancyclostoma duodenale (Hookworm), Necator americanus (Hookworm), Strongyloides stercoralis

Answer 26

Enterobius vermicularis

Also known as a Pinworm. At nighttime, female worms will migrate down to the anus and lay their eggs. Transmitted via the fecal-oral route. People tend to routinely reinfect themselves as they’ll scratch their anus and redo the infectious life cycle

Diagnosis: use scotch tape on your anus to see if eggs are present under microscope

Treatment: Pyrantel pamoate, and albendazole (all intestinal nematodes can be treated with albendazole)

Ancylostoma duodenale and Necator americanus

Hookworms. Larvae penetrate the skin of soles of feet, and once in the blood stream go straight to the lungs so they can ascend the bronchial tree and make their way up to get coughed up, and swallowed, and then back down to the small intestines. Attach to gut wall and suck on blood, etc. Patients developed Iron deficiency anemia.

Diagnosis: look for eggs in the stool and high eosinophil (eosinophilia).

Treatment: albendazole an pyrantel pamoate

Ascaris lumbricoides

Transmitted by eggs in food or water. And hatch in small intestines, go through, enter blood stream, and go to the lungs. Once there, they enter the capillaries into the alveoli, ascend the bronchus, and then are swallowed again and end up in the small intestines.

Of the helminths that migrate through the lungs, Ascaris is the most likely to produce a lung infection. However, main symptom is intestinal obstruction at the iliocecal valve

Diagnosis: eggs in stool, eosinophilia

Treatment: albendazole (however, be aware this drug eliminates the mobility of these bugs by inhibiting their microtubules, so this could still cause a obstruction), and pyyrantel pamoate

Strongyloides stercoralis

Larvae penetrate through the skin of soles of feet. Goes to lungs, climbs bronchial tree, gets swallowed, and enters the GI tract where it matures. Can further infect their host by laying their eggs in the GI tract, where they’ll penetrate and follow the same life cycle arc as before.

Diagnosis: Because eggs are placed in intestinal wall, will not show up in stool, however the larvae will appear in stool, eosinophilia.

Treatment: albendazol, or ivermectin.

Trichenella spiralis

Found in undercooked meat. Causes fever, vomiting, and periorbital edema. Also causes severe myalgia as the ingested cysts will form cysts in striated muscle fibers. Will also present with eosinophilia.

Treatment: albendazole

Question 27

Kaposi’s Sarcoma Associated Virus (HHV8)

Answer 27

Member of the Herpes virus family, thus it is a dsDNA virus that is also enveloped.

Cause of Kaposi sarcoma. AIDS and an immunosuppressed state are associated with Kaposi sarcoma. Kaposi sarcoma presents with violacious (caused by its high vascularity as Kaposi sarcoma causes proliferation of vasculature via dysregulation of VEGF) lesions on the nose, extremities, and mucous membranes (even on the digestive tract, lesions mst commonly occur on the hard palate)

Can also infect B cels, causing Primary Effusion B Cell Lymphoma

Transmission: Sexual contact, including salivary exchange. Main risk groups are AIDS/immunocompromised individuals, eldery Russian men who have lesions down their lower extremities, and people in Africa where the virus is endemic (these adults in particular will present with palatal lesions, and can be potentially fatal in children)

Important to differentiate from Bartonella hensleae (cat scratch disease) as the lesions can look similar. To differentiate, histologically HHV8 will have a lymphocytic infiltrate while Bartonella will have neutrophilic infiltrate

Treatment: Give antiretroviral therapy if they are HIV+ and are undiagnosed, lesions may resolve themselves

Question 28

Norovirus

Answer 28

Positive sense ssRNA, naked virus. Norovirus belongs to the Calicivirus family, and is the most common infection seen from the family.

Produces one long polyprotein that is cleaved into active forms, similar to picornavirus. Replicates in the cytoplasm, like all positive RNA viruses

Outbreaks happen where there are high concentration of individuals (such as cruises). Strong association with daycare facilities and schools. Commonly ingested via contiminated shellfish and other handled raw food

Norovirus causes gastroenteritis, which leads to diarrheal disease characterized by explosive watery diarrhea

Question 29

Orthomyxovirus (influenza) and the concepts of antigenic shift and drift

Answer 29

RNA negative virus. Like all RNA negatives, it has it’s own RNA polymerase to produce positive sense RNA that then uses host machinery to produce viral protein. All negative RNA viruses with the exception are single stranded. Enveloped virus

What is unique about this virus is that, unlike all other RNA viruses, this one replicates in the nucleus, all others replicate in the cytoplasm

There are three strains of influenza (A,B,and C) and is one of four segmented viruses (BOAR, bunyavirus, orthomyxo, arenavirus, and reovirus are segmented) and has 8 segments

Antigenic drift is when there are point mutations in the neuraminidase (NA) or haemagluttinin (HA) genes in influenza virus genome. Reasons we have outbreaks and need new vaccines yearly for this virus

Antigenic shift is when antigenic segments from the virus are mixed and shared between viruses, leading to new surface antigens. Responsible for pandemics. Only possible because the flu virus is segmented

HA is a glycoprotein that binds to sialic acid URT cells and red blood cells, causes them to clump together in blood. Has different type (HA1, 2, 3, etc. Determines what cells it can bind to, aka tropism). Also HA antibodies protect us

M2 protein: creates proper pH that allows for viral encoating. Inhibited by amantadine/rimantadine, prevents uncoating

NA: cleaves sialic acid to release new virions after leaving the cell. Targeted by oseltamivir/anamivir, must be given early

Spread via respiratory droplets (December to February for spread, better to give vaccine in October). Two vaccines: live attenuated inhaled via the nose vaccine or killed injectable form.

Pneumonia is often a complicating factor (Staph aureus and pneuococcus). Treatment with aspirin can cause lots of issues with viral infection, including Reyes syndrome, encephalitis, fatty liver, and liver disease. Associated with Guillain-Barre syndrome

Question 30

Papillomavirus (HPV - Human Papillomavirus 1-4, 6, 11, 16, 18)

Answer 30

dsDNA virus, naked. Over 100 different types. Relevant types: HPV1-4,

HPV 1-4

Cause of verruca vulgaris, which is simple cutaneous common wart. Typically found on hands and feet, but not found on the genitalia. Transmitted via direct contact

HPV 6, 11 (Both viruses cause both diseases)

Associated with Laryngeal papillomatosis, which is a recurrent respiratory papillomatosis, a condition where tumors (papillomas) develop in the airway, typically seen in children. Picked up during vaginal birth and not thought to be sexually transmitted.

Also causes anogenital warts, more formally referred to as Condyloma acuminata. This is transmitted via sexual contact

HPV 16, 18

Known to causes squamous cell carcinomas anogenital cancers (HPV infects squamous cells) (Note, HPV 31 and 33 are also associated with anogenital cancers)

HPV Vaccine: against 6, 11, 16, and 18 (doesn’t cover 31, 33 yet, but 16 and 18 cause 60% of cervical cancer). Under the name gardasil and is an inactivated subunit vaccine.

HPV is the most common STD. Also is capable of disrupting the cell cycle, the virus encodes for proteins E6 and E7 which promote the proteolysis of p53 and Rb (retinoblastoma protein, which is a tumor suppressor) respectively, which lead to upregulation of transition from G1S phase

A hallmark of cervical cancer is Post-coital bleeding (following sex)

Detection: Pap smear is a screening test for cervical cancer, which looks for cells at the transition of columnar epithelium to squamous cell epithelium cells in the cervix. If there is an HPV infection, squamous cells will be altered and look like Koilocytes (large, dense, wrinkled nuclei and may be binucleated. Looks similar to sunny side up eggs).

Immunosuppression and HIV patients are at particular risk for invasive cervical/anal/peniles cancers

Question 31

Paracoccidiodes brasilienis

Answer 31

Systemic fungus localized to South America. Dimorphic like all systemic fungi. Transmitted via respiratory droplets

Structure of the yeast form in the lungs takes on that of a “Captain’s Wheel,” i.e. small buds coming off of a central circle. Much larger than RBCs

Symptoms: Disseminates and causes cervical, axillary, and inguinal LAD. Progresses to the lungs and causes granulomas. Will also present with mucocutaneous lesions

Treatment: Itraconazole for mild infections, amphotericin for severe infections

Question 32

Paramyxovirus (Measles also called Rubeola, Mumps, RSV, Parainfluenza Virus)

Answer 32

ssRNA negative sense. Recall that it replicates in the cytoplasm and is enveloped. Spread via respiratory droplets.

MMR live attenuated vaccine is used to

Measles

Symptoms of measles include the four “C’s”, which are cough, coryza (acute inflammation of the mucous membranes of the nasal cavity, aka stuff nose), conjunctivitis, and Koplik spots. Fever. After Koplik spots, couple days later will develop maculopapillar rash, starting behind the ears and face and then descending. This wash will become confluent (come together)

Major complications include viral or bacterial pneumonia, subacute sclerosing panencephalitis (SSP) which lacks any treatment but diagnosed by Abs in the CSF

Virulence factors: HA and Fusion protein which plays a role in creating syncycia (multinucleated giant cells)

Vitamin A reduces measles morbidity and mortality

Mumps

Replicate in the salivary glands, particularly the parotid glands, leading to parotitis, and testes, which can cause inflammation of the epididymis (Orchitis, unilateral). Can also replicate in the CNS, can cause meningitis.

Associated with HA, NA, and Fusion protein

Respiratory Syncytial Virus (RSV)

Seen in infants less than six months of age. Attaches to G protein of respiratory epithelial cells. Most common cause of bronchiolitis and pneumonia in infants.

Associated with Fusion protein. Treat with Ribavirin in adults. Prevent infants (particularly pre-term) who are susceptible with Palivizumad which is an antibody against the fusion protein

Parainfluenza Virus

Cause of Croup, also known as laryngotracheobronchitis (seal bark cough and inspiratory stridor, high pitched breath sound from turbulent flow in the airway). Common presentation on X-ray is the narrowing of the subglottic region known as the “steeple sign”

Adults simply present with a bad cold

Associated with Fusion protein, HA, and NA

Question 33

Parvovirus B19

Answer 33

ssDNA virus (only ssDNA virus), naked virus. It is the smallest DNA virus known

Transmitted via respiratory droplets and vertically (TORCHES). In the congenital version, causes hydrops fetalis in utero

Causes Slapped Cheek Fever/Fifth Disease (five fingers to a slap)/Erythemia Infectiosum: Rash starts on the face and moves downward.

In adults (classic case is school teacher presenting with the following symptoms), presents with joint pain, arthritis, and edema

Can cause aplastic anemia (depletion of the bone marrow, leaving behind only the adipocytes giving the bone marrow a cobb-webbed look) in sickle cell patients

Question 34

Picornavirus overview

Answer 34

Positive RNA family (pico = small), naked viruses (lack viral envelop), transmitted via fecal-oral route with the exception of Rhinovirus (respiratory spread)

Positive sense RNA uses host machinery to make protein

Protein is made as a polyprotein product that’s cleaved into smaller proteins

Positive sense RNA replicate outside of nucleus because host cell mRNA which is analogous is processed in the cytoplasm

Members: Rhinovirus, HepatitisA, Enteroviruses

Question 35

Plasmodium (malariae, vivax, ovale, and falciparum)

Answer 35

Causes the mosquito borne illness Malaria, characterized by fever and headache, as well as anemia and splenomegally

Identified by blood stain and Giemsa stain to see the parasites within RBCs

Malaria carried by anopheles mosquitios that carry the sporozoites. Once the bug bites, mature to trophozoites in the liver. Eventually, schizont divides into merozoites which burst from hepatocyte and infect RBCs. In the RBC, trophozoite becomes a schizont again, then merozoite, and then then go in to infect more RBCs. Immature schizont has a ring form in the RBC. Merozoites can also form gametocytes, which are the sexual form. The cycle of the parasite is continued when a mosquito bites an infected host and takes in RBCs containing gametocytes

Malariae

Quartan fever cycle (ever 72 hours)

Vivax and Ovale

Produce dormant forms in the liver called hypnozoites. Follow tertian cycle (every 48 hours)

Falciparum

Most severe form of malaria and causes irregular fevers. May also have neurological involvement if parasitized RBCs occlude capillaries in the brain, as well in the kidneys and lungs. Banana shapes in the peripheral blood smear

Treatment

Chloroquine, works by blocking plasmodium heme polymerase. Primaquine to treat the hypnozoites in the liver. Be aware to check for G6PD deficiency in patients as these drugs may induce anemia. Or mefloquine, as many strains are resistant to chloroquine, and useful prophylactic drug for travelers in chloroquin resistant areas. Can also treat with atovaquone/proguanil together for travelers

For infections by Falciparum, treat with artemisins, and possibly atovaquone/proguanil

For very severe malaria infections, use IV artesunate or IV quinidine (unfortunately has causes cinchonism as a side effect, including tinnitus)

Note, sickle cell disease is protective against P. falciparum

Question 36

Pneumocystis jiroveci

Answer 36

Immunocompromised individuals are the only ones that show signs of infection when Pneumocystis is present.

One of the AIDS defining illnesses (similar to Candida esophagitis), presents when CD4 count drops below 200, and also the value at which you start prophylaxis

Causes a diffuse interstitial pneumonia. Coughs won’t be productive like bacterial pneumonia, nor will they show consolidations on X-ray either (may not show anything). If you see anything, will see ground glass X ray infiltrates

PCP diagnosis can be confirmed with bronchoalveolar lavage (BAL). Then, with the BAL sample, you’ll stain it with methamine silver to identify PCP, which will look like disc shaped yeasts

Treatment/Prophylaxis: Both cases you give Bactram, which is combination trimethoprim/sulfonamide (sulfamethoxazol). If patient is allergic to sulfa drugs, treat with pentamidine

Question 37

Polio Virus

Answer 37

Positive RNA in picornavirus family (small RNA), naked virus (like all picornaviruses). Acid labile and can grow at 37C (in GI).

Proliferate in lymphoid tissues (such as Peyer’s pathes) and then spreads to the anterior horn motor neuron bodies, causing paralysis

Causes polio, which leads to asymmetric paralysis, myalgia, and deep tendon reflex loss. Can leads to respiratory loss as well as it ascends. Like the other enteroviruses, polio is the leading cause of aseptic viral meningitis, marked by low glucose, no bacteria, and high protein levels in the CSF

No treatment, but preventitive. Salk: killed polio vaccine. Sabin: live attenuated vaccine given orally

Killed bypasses GI, so it doesn’t form IgA antibodies, only IgG, which isn’t ideal because we want IgA to protect at mucosal surfaces, live vaccine does produce IgG and IgA. Downside of live one is that it can shed in feces and infect someone else, causing paralysis

Question 38

Polyomavirus (JC and BK)

Answer 38

These viruses are naked dsDNA viruses with circular genome.

JC Virus

JC stands for John Cunningham virus and is the cause of progressive multifocal leukoencephalopathy (PML).PML is a demyelinating disease that kills oligodendrocytes that produce myelin for the CNS. Progesses to the point where most patients who get it die with months. Would see non-enhancing multifocal brain lesions in the white matter of the brain.

Half the population has it, but asymptomatically. Typically only affects people who are immunocompromised, or HIV patients with less than 200 CD4 count.

BK Virus

Causes nephropathy and other diseases of the urinary tract including hemorrhagic cystitis (similar to adenovirus, its urine in the blood and bladder pain) however this is more implicated in transplant patients (name actually comes from the initials of a transplant patient whose urine was isolated)

Question 39

Poxvirus (smallpox, cowpox, Molluscum Contagiosum)

Answer 39

DNA virus. Enveloped. Largest known DNA virus

What is unique about this virus is that it is packaged with all machinery necessary for its replication: make their own envelopes, only DNA virus that replicates in the cytoplasm, DNA dependent RNA polymerase (which is why it doesn’t need to go to nucleus)

Will form intracytoplasmic inclusions at sites of their replication called Type B, or Guarnieri Bodies

Dumbbell shaped core

Smallpox

Also known as variola, causes raised blisters on the skin. Important to distinguish between chicken pox (varicella zoster). Smallpox lesions will all be the same age (same maturity) whereas chicken pox age varies (blisters, healing blisters, and small scabs). Eradicated, and we no longer vaccine (used cowpox virus prior). Can be used as a bioweapon as it exists in labs

Cowpox

Transmitted via infected cow utters. This was the virus used for the smallpox vaccine, which lead to its eradication

Molluscum contagiosum

Causes flesh-colored, dome-shaped, umbilicated (little dimple in the middle) skin lesions which look like a snail’s shell. Most common found in children typically on the trunk. In healthy adults, will cause single, focal lesion. However, in HIV infected adults will lead to diffuse molluscum contagiosum

Question 40

Reovirus (Rotavirus)

Answer 40

dsRNA virus (only one), so no +/- classification. Replicates in the cytoplasm, nonenveloped. Segmented (BOAR - bunya, orthomyxo, arena, reo) with between 9-11 segments depending on the virus

Rotavirus

Transmitted oral-fecal route and causes toxin-mediated, explosive diarrhea, watery similar to norovirus. Caused by NSP4 encoded on the viral genome, increases chloride permeability leading to more secretions by gut epithelium.

Seasonal virus, typically in the wintertime. Chilren are at high risk, especially in infants and children in daycare settings

Treatment: Supportive care via oral rehydration.

Vaccine: Live attenuated virus, taken orally. First dose given before three months of age due to increase side effects and decreased efficacy (causes telescoping of the bowel, known as intussusception)

Colorado Tick Virus

Causes fever, myalgia, vomiting

Question 41

Rhabdovirus (Rabies)

Answer 41

ssRNA negative sense virus, enveloped virus. Hallmark of Rhabdovirus is that it looks bullet shaped on EM. Also has a helical capsid

Carried in rodents such as foxes, skunks, and bats (top carries in the US)

The virus has a glycoprotein that binds to the nicotinic ACh receptors in the post-synaptic membrane at the NMJs. In these cells, they replicate. After incubating for weeks, it travels retrograde up neurons to the dorsal root ganglia. As it spreads initially, it causes tingling and muscle spasms. However, upon reaching the salivary glands causes increase salivation and excruciating spasm of throat and larynx, causing dysphagia.

Finally, leads to high fever, encephalitis, neuronal death, and is invariably fatal.

Diagnosed clinically, based on past exposure, or by biopsy/autopsy by finding Negri-bodies which are eosinophilic inclusions in neuronal bodies in the hippocampus pyrimidal cells or cerebellum Purkinje cells

Treatment is with human Ig against the virus and giving the viral vaccine (killed virus). Give treatment even if not sure if you got bit as after symptoms present it’s too late

Question 42

Rhinovirus

Answer 42

Family: Picornavirus, small RNA virus, +ssRNA, nonenveloped

Cause of the common cold. Acid labile, unique to Rhinovirus in picornavirus. Spread via respitory transmission or fomites (bad hands). Enters via host cells on ICAM-1

Grows best in 33, cooler than most viruses, why it ends up in URT

113 serotypes, so many different flavors, which is why it’s hard to vaccinate so explains why there’s no vaccination for Rhinovirus and it can’t be treated with

Question 43

Sporothrix schenckii

Answer 43

Cutaneous mycosis fungi. Found on rose thorns, tree bark, and other plants. Dimorphic fungus. Resembles cigar shape yeast under microscope

Causes Rose gardener’s disease (lymphocutaneous sporotrichosis), which is initiated by traumatic contact with one of the above plant life. The infection then spreads in an ascending pattern from the focal lesion along the path of draining lymphatics and presents as red bumps

Culture is the gold standard of diagnosis, but biopsy of the lesion will show granulomas consisting of histiocytes, multinucleated giant cells, and cigar shaped budding yeasts

Treatment: Itraconazole. Can also treat with saturated potassium iodide, but this is an older treatment

Question 44

Togaviruses (EEE, WEE, VEE, Chikungunya, Rubella)

Answer 44

Positive sense RNA viruses, enveloped (hense the name toga), like other positive sense RNA viruses, they replicate in the cytoplasm. Similar to picornavirus, togaviruses produce polyprotein that is cleaved into functional proteins by proteases

Arbovirus (arthopod-borne virus): No treatment, just protection from mosquitos
Western, Eastern, and Venezuelan Equine Encephalitis Viruses: Cause encephalitis. Vaccine exists, but only for at risk patients
Chikungunya: Causes fever and joint pain up to months-years. More serious in elderly and newborns. No vaccine or antivirals exist

Rubella (German Measles)
Childhood exanthem (widespread rash)
Three separate presentations: congenital, childhood, and adult
Childhood: Causes postauricular and occipital lymphadenopathy, maculopapular rash that begins on the face and spreads downward. Will also see fever and fatigue, and rash moves faster than Measles and is generally only around for three days. Spread via respitatory droplets
Congenital: Because the virus can cross the placenta, can be born with virus and have distinct symptoms: mental retardation, microcephaly, blindess, deafness, cataracts, jaundice, Patent Ductus Arteriosus, Pulmonic Stenosis, Purpuric Blueberry Muffin Rash, and Radiolucent Bone Lesions
Adult: Lymphadenompathy and fever, but will also see arthralgia and arthritis.

Rubella has no treatment, but is covered by the MMR (Mumps, Measls, Rubella) Live Attenuated Vaccine that produces both humoral and cell mediated immunity (but women who are planning on getting pregnant or immunecompromised should avoid getting). Also, common in immigrants as they may not have been vaccinated

Question 45

Toxoplasma gondii

Answer 45

Particularly of interest for (at risk for transplacental transfer) and immunocompromised patients. It is an intracellular parasitic protozoan that can infect any warm blooded animal. Carried by 30% of individuals world wide asymptomatically

Transmitted via contaminated meat that contains toxo tissue cysts, or by water/vegetables that are contaminated by oocytes shed in the feces of infected animals, or mother-to-fetus if the mother is exposed during pregnancy (one of the TORCHES infections, is the T). Commonly, it is spread via cat feces

In immunocompromised patients, Toxo will cause ring enhancing lesions on CT or MRI of the brain, encephalitis. May have to do brain biopsy to differentiate from CNS lymphoma. Can also develop chorioretinitis

Congenital toxo causes intracranial calcifications, hydrocephalus, seizures, and chorioretinitis. Can also present with deafness

Diagnosis: done by serology (doesn’t always indicate active infection, and large majority of population has been exposed to toxo in the past) or biopsy (looking for intramuscular cysts)

Treatment: sulfadiazine and pyrimethamine. Also, need to give prophylaxis for HIV patients when their CD4 count drops below 100 and IgG is positive for toxo: TMP/SMX (Bactram)

Question 46

Varicella Zoster Virus (VZV)

Answer 46

DNA virus of the Herpes virus family. Like all Herpes viruses, it is an enveloped virus. Like other Herpes viruses, able to stay latent: remains latent in dorsal root ganglia. Reactivation dependent on stress, aging, or immunocompromised state. This leads to the Herpes zoster, better known as Shingles, form. TORCH infection

Chicken Pox

Transmitted via respiratory droplets or by ruptures of the vesicles directly.

Cause of chicken pox, which presents with fever, headache, vesicular (dew drops on a rose) rash similar to HSV. These lesions will also be at different stages, unlike smallpox where all blisters are the same stage.

In adults, VZV can cause pneumonia (main cause of morbity in adults) and encephalitis (especially in the immunocompromised)

Can use Tzank smear to screen for multinucleated giant cells (similar to HSV)

Vaccine: Live attenuated vaccine for children

Treatment: acyclovir for children ages >12, adults, and immunocompromised

Shingles

Also known as Herpes zoster, has dew drop on a rose appearance with dermatomal distribution (makes sense because residing in the dorsal root ganglia, when reactivated it will go towards the dermatome its nerve is supplying). Rarely crosses the midline, however when it does referred to as disseminated VZV (red flag that a person is immunocompromised). These rashes are incredibly painful, and can remain so after the rash subsides (postherpetic neuralgia)

Can also be found in the trigeminal nerve if immunocompromise, leading to Herpes Zoster Opthalmicus, which is vision loss if V1 is affected

Vaccine: recommended for adults over 60, also live attenutated Zoster vaccine. Keep away from immunocompromised patients, can give to HIV as long as CD4 greater than 200

Treatment: can also give acyclovir, or more commonly given is Famciclovir. Can also use valacyclovir.

Congenital Varicella Syndrome

Since VZV is a TORCH infection (as are all Herpes viruses), can cause birth defects. Limb hypoplasia, cutaneous scarring in dermatormal pattent, and blindness