Scarlet Fever

Scarlet fever is a syndrome characterized by exudative pharyngitis, fever, and scarlatiniform rash. 

-It is caused by toxin-producing group A β-hemolytic streptococci

-Symptoms and signs include sore throat, fever, rash, strawberry tongue, flushed face, and circumoral pallor 

-Rash: Diffusely erythematous rash resembling a sunburn; superimposed fine red papules give the skin a sandpaper consistency; it blanches on pressure, moves from torso to extremities, prominent on the face, chest, palms, fingers and toes; fades in 2-5 days 

-Forchheimer spots: Petechiae and punctuate red macules on the soft palate and uvula 

-Pastia lines are pink or red lines seen over the elbows and axilla during scarlet fever

-Treatment of scarlet fever is by antibiotics 


Chlamydial infections


-Chlamydiae are obligate intracellular bacteria, possess both DNA and RNA, and have a cell wall similar to that of gram-negative bacteria.

-Chlamydiae that infect humans are divided into three species, Chlamydia trachomatis, Chlamydia pneumoniae, and Chlamydia psittaci

Chlamydia trachomatis: Chlamydia trachomatis infects only humans; incubation period: 1-3 weeks 

Eye infections: Conjunctivitis, trachoma (leading cause of preventable infectious blindness)

Lung infections: Pneumonia 

Genital infections: Urethritis, Lymphogranuloma venereum 

Joint infections: Reiter’s syndrome 

 Chlamydia pneumoniae: Chlamydia pneumoniae infects only humans; it can cause upper and lower respiratory infections 

Chlamydia psittaci: Chlamydia psittaci infects birds, humans and other animals; it causes psittacosis 

Symptoms & Signs 

Genital infection: Dysuria, urethritis, discharge, which is clearer and less purulent than seen with gonorrhea; Chlamydial infection is asymptomatic in 75% of females


Nucleic acid amplification test (NAAT): is the recommended test for screening asymptomatic at-risk and symptomatic individuals 

Culture: In culture, C. trachomatis forms intracytoplasmic inclusions containing glycogen, whereas C. psittaci and C. pneumoniae form inclusions that do not contain glycogen.

Serologic tests:  mainly to diagnose infections by C. psittaci and C. pneumoniae 


-All chlamydiae are susceptible to tetracyclines, such as doxycycline, and macrolides, such as erythromycin and azithromycin.

-Treatment should be offered to sex partners 

-Because of the high rate of coinfection with C.trachomatis and gonococci, any patient with a diagnosis of chlamydia should also be treated for gonorrhea and vice versa 

-Chlamydia urethritis: Azithromycin 1 g orally in a single dose or Doxycycline 100 mg orally twice a day for 7 days 

-The drug of choice for neonatal inclusion conjunctivitis and pneumonia caused by C. trachomatis is oral erythromycin. 

-The drug of choice for C. psittaci and C. pneumoniae infections and for lymphogranuloma venereum is a tetracycline such as doxycycline.


Untreated chlamydia can cause serious complications 

Men: Epididymitis, sterility

Women: PID, ectopic pregnancy, infertility 


-There is no vaccine against any chlamydial disease

-Educate patients on safer sex practices.

Q.What are the tests of choice for the diagnosis of genital C.trachomatis infections? Nucleic acid amplification tests (NAATs) Q.What is the drug of choice for Chlamydia trachomatis sexually transmitted disease? Azithromycin


Running German Shepherd


Rabies is a rapidly progressive, acute, fulminant, and fatal encephalitis in humans and animals that is caused by infection with rabies virus.

-Rabies virus is usually transmitted to humans by the bite of an infected animal.

-Live virus enters the nerve tissue at the time of the bite, multiplies at the site, and then spreads centripetally along peripheral nerves toward the spinal cord or brain stem via retrograde fast axonal transport. It replicates in gray matter and then spreads  to the salivary glands, adrenal glands, and heart. 

Symptoms & Signs 

-The average incubation period is one to three months. 

-The clinical spectrum can be divided into three phases

1.Prodromal phase: 

-The first symptom is usually the paresthesia at the bite site 

-Patient later develops malaise, headache, photophobia, fever, anorexia, nausea, vomiting and sore throat 

2.Acute neurologic phase: 

Hydrophobia (fear of water), Aerophobia (fear when feeling a breeze) 

-Sympathetic overactivity (Increased salivation, ‘foaming at the mouth’, perspiration, lacrimation, pupillary dilatation, nervousness)

-Psychotic symptoms (hallucinations, delusions, bizarre behavior)

-Two acute neurologic forms of rabies are seen in humans: 

the encephalitic (furious) form in 80% and

the paralytic form in 20%.

3.Coma: Convulsive seizures, coma and death

-The major cause of death is cardiorespiratory arrest. 


1.Rabies antigens: diagnosis by rabies specific antigens 

2.Serology: Diagnosis by rabies specific antibodies,  detected by immunofluorescence or neutralization tests. 

3.Viral isolation: Isolation of the virus in the brain neurons. 

Negri bodies: the most characteristic pathologic finding in rabies; They are eosinophilic cytoplasmic inclusions in the brain or the spinal cord. They are composed of rabies virus proteins and viral RNA 

4.Animal observation: 

‘Rabid or suspected rabid’ animals: should be killed humanely immediately after the bite and sent for laboratory examination of neural tissues 

‘Normal’ animals: should be held for observation for 10 days 

If they appear abnormal during or after 10 days: kill humanely and send tissues to laboratory 

If they appear normal during or after 10 days: individualized treatment 


Avoid contact with any unfamiliar domestic animals and wild animals 

Immunize all household dogs and high risk pets 

Vaccination: Four 1-mL doses of rabies vaccine should be given IM in the deltoid area. 

Post-Exposure Prophylaxis 

It involves wound cleaning, vaccination and passive immunity 

Wound cleaning: 

-Thoroughly clean the wound with soap and antiseptics 

-Animal bite wounds should not be sutured

Vaccination: Four doses of rabies vaccine over a 14 day period 

-Give the vaccine only in deltoid region in adults or anterolaterial thigh in children 

Never administer the vaccine in the gluteal area because antibody responses have been lower after administration at this site 

-Pregnancy is not a contraindication for immunization.

Passive immunity: One dose of HRIG along with the first dose of the vaccine 

-HRIG is not indicated beyond the 7th day after vaccination is begun, because an antibody response is most likely occurred 

-HRIG should never be administered in the same syringe or into the same injection site as the vaccine, because the antibody and vaccine will neutralize each other.

-HRIG should not be given to those with immunoglobulin A deficiency, because small amounts of immunoglobulin A present in HRIG might cause a severe allergic reaction.


-There is no successful treatment for clinical rabies. 

-Symptomatic and Palliative treatment using sedatives, antipsychotics, anxiolytics, and pain killers


Poliomyelitis is a disease of the anterior horn motor neurons of the spinal cord and brainstem caused by the poliovirus. 

-Anterior horn cells control the skeletal muscle cells of the trunk and limbs 

-In up to 95% of cases, poliovirus infection is asymptomatic 

-the viral transmission is oral to oral or fecal to oral 

-Acutely, the polio virus enters the body through the GI tract, reproduces in the GI lymphoid tissue, and then spreads to the large motor nuclei of the spinal cord, the brainstem, reticular formation, hypothalamus, thalamus, cerebellum and cerebral cortex. 

Symptoms & Signs

Thankfully, not every polio infection results in paralysis. It can be divided into following types based on the severity. 

Abortive poliomyelitis: fever, headache, vomiting, diarrhea, constipation, and sore throat lasting 2–3 days.

Nonparalytic poliomyelitis: Above symptoms plus meningeal irritation and muscle spasm but no frank paralysis 

Paralytic poliomyelitis: 

Asymmetrical paralysis; Proximal limb muscles are more often involved than distal, and lower limb involvement is more common than upper. 

1.Spinal poliomyelitis: involves the muscles innervated by the spinal nerves, flaccid and weak muscles, absent tendon reflexes and fasciculations 

2. Bulbar poliomyelitis: involves the muscles innervated by the cranial nerves  IX and X; seen in up to 20 percent of polio patients with paralysis; affects swallowing, speech, facial muscles 

Post-poliomyelitis syndrome:  Fatigue, pain, respiratory problems, sleep problems, increased risk of falls 

Guillain-Barré syndrome: Always think of GBS in the differential diagnosis of polio paralysis. GBS is distinguished from polio by its symmetry, disturbances in sensation, lack of preceding aseptic meningitis, absence of a CSF pleocytosis, presence of multifocal demyelination on electrodiagnostic testing 


Virus isolated and typed from throat swabs and rectal swabs; PCR amplification of poliovirus RNA from the CSF 


Treatment of poliomyelitis is supportive 

-Pain relief, physical therapy

-Mechanical ventilation for respiratory failure 

-Intubation or tracheostomy for secretion control 


the trivalent live OPV, the inactive (Salk) parenteral vaccine is currently used in the United States for all four recommended doses (at ages 2 months, 4 months, 6–18 months, and at 4–6 years).

Rubella Infection


Rubella is an acute febrile illness caused by Rubella virus, a single-stranded RNA virus of Togavirus family 

-It is commonly known as German measles or 3-day measles. 

-the virus enters the body through inhalation 

-it replicates in the upper respiratory tract and spreads in the bloodstream to other organs, skin and lymphoid tissues 

-the incubation period is 14 to 21 days 

-the virus has high infectivity but low virulence

Symptoms & Signs 

A.Infection in young children and adults: Fever, rash, malaise, arthralgia, lymphadenopathy, which is most prominent in the posterior cervical and postauricular areas.

Arthralgia: The most common complication of Rubella is arthralgia, and it occurs most frequently in women 

Rubella rash: A fine, pink maculopapular rash begins on the face and rapidly spreads to the trunk and extremities. It lasts for 3 days.  

B.Congenital Infection

-The greatest significance of rubella is not the acute illness but the risk of fetal damage in pregnant women. 

-the risk of fetal malformation is highest in the early stages of pregnancy 

-Intravenous immune globulin injected into the mother does not protect the fetus against rubella infection 

-The classic triad of congenital rubella consists of cataracts, cardiac abnormalities, and deafness. 

-The most common developmental manifestation of congenital rubella is mental retardation.

A.General: Failure to thrive, growth retardation, malabsorption  

B.Cerebral: Microcephaly, encephalitis

C.Ocular: Cataracts, glaucoma, microphthalmia, chorioretinitis 

D.Deafness: Sensorineural in most cases 

E.Cardiac: Pulmonary artery stenosis, pulmonary valvular stenosis,

patent ductus arteriosus, ventricular septal defect

F.Hematologic: Thrombocytopenia, lymphopenia, intravascular coagulation 

G.Skin: Blueberry muffin purpura on head, neck and trunk 


Confirmation of the diagnosis requires laboratory studies. 

A. Nucleic Acid Detection: Rubella virus nucleic acid is detected using RT-PCR 
B. Isolation and Identification of Virus: Rubella virus isolated from nasopharyngeal or throat swabs 
C. Serology: Rubella HI test 


Infection in young children and adults: Rubella is a mild, self-limited illness; no specific treatment is indicated; Patients should be isolated for 7 days after rash onset

Congenital infection: there is no specific treatment 


The primary purpose of rubella vaccination is to prevent congenital rubella infections. 

-Live attenuated rubella vaccine (MMR or MMRV) given in two doses, first dose at 12 to 15 months of age and the second dose at 4 to 6 years of age

-Pregnancy should be avoided for at least 28 days after vaccination.

-Pregnant women should not receive the vaccine, but should be screened for rubella IgG antibodies



-Mumps is a viral infection which primarily affects salivary glands. 

-Mumps virus is a single-stranded RNA virus and is a member of paramyxovirus family 

-The virus is transmitted by the respiratory route via droplets, saliva, and fomites.

-The highest incidence of infection is usually during the late winter and spring months, but it can occur during any season.

-It is observed to occur most frequently in the 5- to 15-year age group. 

The incubation period of mumps is ~19 days

-Viremia allows the virus to travel to all body organs, including salivary glands and central nervous system.

Symptoms & Signs 

The prodrome of mumps consists of low-grade fever, headache, anorexia malaise, and myalgia

-Hallmark of mumps: Unilateral or bilateral parotid swelling

-Other manifestations: Epididymo-orchitis, pancreatitis, acquired deafness, aseptic meningitis and encephalitis 

-Mumps during the first trimester of pregnancy increases the risk of miscarriage


-Diagnosis is made based on clinical findings or/and detection of viral RNA by reverse-transcriptase PCR (RT-PCR) or viral culture 


-Mumps is a self-limited, usually mild, disease. 

-Treatment is supportive and consists of antipyretics, fluids, and analgesics. 

-Stay home from school or work for 5 days after symptom onset.


-Usually Natural infection confers life-long protection

The MMR vaccine is given routinely subcutaneously to all healthy children at age 12–15 months with a second dose at age 4–6 years.

-Mumps vaccine contains live attenuated virus. It is not recommended for pregnant women



Measles is an acute, highly infectious disease characterized by fever, respiratory symptoms, Koplik spots and a maculopapular rash. 

-Measles virus is a highly contagious, spherical, single-stranded, enveloped RNA virus that is a member of the Paramyxoviridae family.

-The virus gains access to the human body via the respiratory tract and is transmitted primarily by respiratory droplets

-Measles is endemic throughout the world.

Symptoms & Signs 

Incubation period: The incubation period for measles is 10 days to fever onset and 14 days to rash onset. 

Prodromal Phase: Cough, Coryza, Conjunctivitis, high-grade fever. Coryza consists of nasal obstruction, sneezing, and sore throat resembling upper respiratory infections. 

Koplik spots

-Pathognomonic of measles

-typically occur 2 days before the rash and only last 12 to 72 hours. 

-they appear as small, irregular and red with whitish center on the palatal or buccal mucosa opposite the molars or on vaginal membranes – ‘grains of sand’ or ‘table salt crystals’ 

Rash: Maculopapular rash progressing in  “downward and outward” fashion; appears 3 – 4 days after onset of prodrome, begins on the face and behind the ears; then spreads to the trunk and extremities, including the palms and soles

-Patients are contagious during the prodromal phase (2–4 days) and the first 2–5 days of rash In the hospital setting, patients with measles should be placed under air-borne precautions.


-Diagnosis is made based on clinical features 

-Labs: Leukopenia, thrombocytopenia, proteinuria  

-A positive serum immunoglobulin (Ig) M antibody for measles confirms the diagnosis. Treatment 

-Antipyretics, fluid resuscitation 

-Vitamin A treatment to reduce morbidity and mortality 

-Limited use of antivirals like ribavirin 

-Serious complications include otitis media, encephalitis, pneumonia, and bleeding disorders. 

Infection confers lifelong immunity.



Two doses of vaccine are estimated to be 97% protective. 

Children: Measles, mumps, and rubella vaccinations should be given as MMR or MMRV at 12–15 months and again at 4–6 years of age. 

Adults: Adults born in 1957 or later should have at least one dose of MMR vaccine 

Contraindications: Vaccine contraindicated in pregnant women, women intending to become pregnant within the next 28 days, immunocompromised persons, and persons with an anaphylactic reaction to a prior dose or vaccine components like neomycin, gelatin, and in children receiving high-dose corticosteroid therapy 

Infectious Mononucleosis – Mono


Infectious mononucleosis is a clinical syndrome caused by  Epstein-Barr virus, but other viruses can also cause similar symptoms.

-The virus is transmitted through bodily fluids such as saliva (‘kissing disease) and sputum 

-It occurs mainly in adolescents and young adults 

Symptoms & Signs 

-It is characterized by a triad of fever, pharyngitis, and lymphadenopathy.

-Other symptoms include malaise, anorexia, myalgia, transient bilateral upper lid edema (Hoagland sign), radiation of pain to the left shoulder (Kehr’s sign) and splenomegaly 

-Highly suggestive findings: Epitrochlear adenopathy, posterior cervical lymphadenopathy 

-A morbilliform or papular rash, usually on the arms or trunk 


Antibody Tests: The most commonly performed diagnostic test is a rapid heterophile antibody test (Monospot test) 

White blood cell counts: Increased number of circulating white blood cells with a predominance of lymphocytes

Other labs: Elevated aminotransferases 


-The typical illness is self-limited and most symptoms resolve within 2–4 weeks.

-Symptomatic treatment: Antipyretics, analgesics, oral fluids, rest 

-Misdiagnosing it  as Strep throat and treating with amoxicillin can result in patient getting a rash and you getting a disappointed patient and their parents 

-Upper airway obstruction and severe hematologic complications: Consider corticosteroids 

-Potential complications: Splenic rupture, airway obstruction, pneumonitis, hemolytic anemia, thrombocytopenia, aplastic anemia, encephalitis, optic neuritis, meningitis, Guillain-Barré syndrome

– Patients should avoid contact sports and heavy lifting for 4 weeks due to the risk of splenic rupture

Herpes Zoster (Shingles)


-Herpes zoster results from reactivation of latent varicella-zoster virus infection within the sensory ganglia 

-It is usually characterized by a painful, unilateral vesicular eruption in a dermatomal distribution 

-It is usually occurs among adults, but rarely occurs in other age groups also. 

Symptoms & Signs 

-Most commonly involved sites of herpes zoster: trigeminal, thoracic and lumbar 

-It is usually confined to a single dermatome on one side and associated with burning pain in the affected area, fever, malaise, headache

-The rash starts as grouped vesicles and later become pustular and crusty. 

Herpes zoster ophthalmicus: Lesions on tip of nose, inner corner of eye and root and side of nose (Hutchinson sign) 

Herpes zoster oticus (Ramsay Hunt syndrome): vesicles in the ear canal, hearing loss, vertigo, tinnitus, Bell palsy; due to reactivation of VZV within the geniculate ganglion. 

-The lesions are considered infectious until they dry and crust over 


-Diagnosis is based on the clinical presentation


Antiviral agents: Acyclovir, valacyclovir, famciclovir, beneficial if started within 72 hours after the eruption of the rash 

Anterior uveitis: topical steroids, cycloplegics 

Corticosteroids do not prevent the development of postherpetic neuralgia


-Two shingles vaccines (Zostavax and Shingrix) are available for adults who have had chickenpox. 

-Shingrix is preferred over Zostavax.

-Shingrix is approved and recommended for people age 50 and older, including those who’ve previously received Zostavax. 

-Zostavax isn’t recommended until age 60. 

-Shingles can spread through direct contact with herpes zoster lesions 

-Patients should avoid contact with pregnant women who have never had chickenpox or varicella vaccine, immune deficiencies, and premature infants. 

Q.What is the most common complication of zoster in elderly adults? Postherpetic neuralgia 

Q. What is the most common cause of acute retinal necrosis? Herpes zoster virus

Chickenpox by Dr.Paul Kattupalli


-Chickenpox is an infection caused by the varicella-zoster virus. 

-VZV is a double-stranded, linear DNA virus 

-VZV infection causes two clinically distinct forms of disease: varicella (chickenpox) and herpes zoster (shingles).

-It is highly contagious, spreads readily by airborne droplets and by direct contact. 

Symptoms & Signs 

-Varicella most frequently occurs in children <10 years old but may occur at any age. 

-Varicella usually is a mild, self-limited illness in healthy children. 

-Fever, headache, malaise, papules, vesicles, crusts and scabs 

-It appears on the back of the head and ears, and then spreads centrifugally to the face, neck, trunk, and proximal extremities. 

-Vesicles are described as ‘dew drops on a rose petal’


-Diagnosis is clinically made based on history and physical examination

-Tzanck smear of the vesicle: Giant cells with inclusion bodies

-Histology: “Balloon degeneration” of cells with basophilic nuclei 


-For healthy children  ≤12 years, varicella is mostly self-limited; no antiviral therapy

-Immunosuppressed children and adults: antiviral therapy 

-Do not give aspirin because it is associated with the onset of Reye syndrome in the setting of a viral infection 

-Breastfeeding is encouraged in infants exposed to or infected with varicella. 


-A live attenuated varicella vaccine is available. 

-It is administered subcutaneously

-It is given in two doses; first dose at age 12 through 15 months, the second dose at age 4 through 6 years

Herpes Simplex Infections


Herpes simplex virus infections occur equally between the sexes throughout the year. 

-Penn State Students in State College are at high risk when they touch lesions of herpes

HSV-1 transmission typically occurs via oral-oral, oral-genital, or genital-genital contact.

HSV-2 lesions largely involve the genital tract, with the virus remaining latent in the sacral nerve root ganglia (S2–S5) 

Symptoms & Signs 

Both viral subtypes can cause genital and oral–facial infections

The infections caused by the two subtypes are clinically indistinguishable.

Gingivostomatitis and pharyngitis:   the most frequent clinical manifestations of primary HSV-1 infection; presents as small, grouped vesicles on an erythematous base, burning and stinging sensation, swollen and tender burning and stinging 

Genital: most genital infections are caused by HSV-2; presents with bilateral genital ulcerations and tender lymphadenopathy. 

Ocular disease: HSV keratitis presents with vision loss, pain, and discharge; it is a major cause of blindness from corneal scarring and opacity. 

Neonatal & Congenital infection: Neonatal HSV can present as excessive tearing, eye pain, conjunctival edema, vesicular lesions of the mouth, palate, tongue, seizures, irritability, fever, multiple organ failure

CNS Disease: Both viruses can cause encephalitis; the temporal lobe is often involved; it presents with 

the rapid onset of fever, headache, seizures, focal neurologic signs, and impaired consciousness

Bell’s Palsy: HSV-1 is a cause of Bell palsy (facial nerve paralysis)

Esophagitis & Proctitis: usually presents with dysphagia or odynophagia, fever, retrosternal chest pain 

Erythema multiforme: HSV infection is the most common cause of EM; Cutaneous eruptions occur 2 to 7 days after herpes simplex infection 


Diagnosis can be made by physical examination; Direct fluorescent antibody slide tests, viral culture, polymerase chain reaction 


Early antiviral therapy within 72 hours of symptom onset

Antiviral drugs: Acyclovir, Famciclovir, Valacyclovir 

Severe or frequent recurrences: Chronic suppressive therapy with antivirals 

Keratitis: The usage of topical corticosteroids may exacerbate the infection


Male circumcision is associated with a lower incidence of acquiring HSV-2 infection.


Q. What is the most frequent sign of HSV reactivation disease? Herpes labialis 

Q. What is the most frequent etiologic agent of Erythema multiforme? Herpes simplex virus 

Q. What is the most common cause of fatal sporadic encephalitis in the United States? HSV-1 encephalitis 

Tourette Syndrome


-Gilles de la Tourette syndrome is a chronic neuropsychiatric disorder characterized by multiple motor and phonic tics. 

-Tics are sudden, involuntary, rapid, uncontrollable, repetitive, nonrhythmic, stereotyped movements with no purpose. 

-Symptoms begin before 21 years of age, most often by the age of 11

-the course is one of remission and relapse.

-the disorder is more common in males than females 

Symptoms & Signs 

Tics typically start early, at 3–5 years of age, and peak around 9–12 years

Phonic Tics: Throat-clearing,gruting, barking, sniffing, hissing

Coprolalia: Vulgar or obscene speech 

Echolalia: Parroting the speech of others 

Echopraxia: Imitation of others’ movements 

Palilalia: Repetition of words or phrases 

Motor tics: Eye Blinking, facial grimacing, sniffing, hopping, jumping, and kicking, body gyrations, complex obscene gestures, neck jerking, shoulder shrugging 

Sensory tics: Tics consisting of pressure, tickling, and warm or cold sensations 

Behavioral disorders: Anxiety, obsessive-compulsive disorder, attention deficit disorder, depression 


Diagnosis is made based on history and physical examination

Laboratory tests are normal 


Behavioral therapy: Cognitive behavioral therapy, Habit reversal training 


α-Adrenergic agonists: the first-line therapies

Clonidine: Most frequent side-effects are sedation, orthostatic hypotension, constipation 


Antipsychotics: Risperidone, Aripiprazole,olanzapine, ziprasidone, Haloperidol, Pimozide 

Botulinum toxin A injections 



-the disorder is chronic, with waxing and waning

-Majority will experience significant improvement by the end of adolescence (80%).