Comprehensive Study Notes on Viral Diseases

Viral Diseases

Adenovirus

• Worldwide distribution, year-round occurrence.

• Most common in young infants, young children, and military recruits.

• Responsible for 2-7% of childhood viral respiratory infections and 5-11% of viral pneumonia and bronchiolitis.

• Causes morbidity and mortality in immunocompromised patients (HIV, COPD, organ transplant, cardiac surgery, chemotherapy patients).

Clinical Findings

• Incubation period: 4-9 days.

• Common cold symptoms: rhinitis, pharyngitis, mild malaise without fever, conjunctivitis.

• Nonstreptococcal exudative pharyngitis: fever (lasting 2-12 days), malaise, and myalgia.

• Lower respiratory tract infection: bronchiolitis (cough, rales) or pneumonia.

• Other conditions: hemorrhagic cystitis in children, gastroenteritis, mesenteric adenitis, acute appendicitis, rhabdomyolysis, and intussusception.

Diagnosis \& Treatment

• Lab Findings: Antigen detection assays (direct fluorescence assay or enzyme immunoassay) are rapid but have 40-60% sensitivity compared to viral culture. Negative rapid assays require PCR or viral culture for diagnosis.

• Chest CT: Multifocal consolidation or ground-glass opacity without airway inflammatory findings.

• Treatment: Symptomatic.

• Ribavirin or cidofovir used in immunocompromised patients with occasional success.

Influenza (A \& B)

• Causes COPD exacerbations/hospitalizations.

• May lead to pneumonia, sepsis, respiratory failure, encephalitis, myocarditis, meningitis, rhabdomyolysis, renal failure.

High-Risk Groups

• Age <5 or >65 years, pregnant, immunocompromised, comorbidities (DM, HTN, CAD, CKD).

Prevention

• Influenza vaccine (inactivated for ≥6 months, high dose for 65+).

• Live attenuated vaccine (nasal, never give to pregnant or immunocompromised patients).

• Contraindications: prior anaphylaxis, <6 months, Guillain-Barre within 6 weeks of previous vaccine.

Symptoms/Signs

• Sudden onset, fever, nonproductive cough, myalgia, headache, chills, diaphoresis, sore throat, rhinorrhea, GI symptoms.

Diagnosis

• Rapid PCR (preferred), viral culture.

Treatment

• Supportive care.

• Oseltamivir: reduces symptoms, best if started within 48-72 hours of symptom onset.

• Zanamivir (inhaled): avoid in patients with respiratory issues.

• Amantadine: works against Flu A only.

COVID-19

• Caused by SARS-CoV-2, emerged in Wuhan, China, leading to a pandemic.

• Member of lineage B of Betacoronavirus genus (includes SARS-CoV-1) and related to MERS-CoV.

Risk Factors

• Advanced age ( >95% occur in people >45 yrs and >80% in people > 65 yrs) is the principal risk factor for severe illness.

• Male sex, overweight/obesity, substance use (ETOH, opioid, cocaine), smoking.

• Pregnancy, chronic lung disease (COPD, asthma), cancer, immunodeficiency, hemoglobin blood disorders, CVD, cognitive impairment, heart conditions, OSA, chronic inflammatory/autoimmune diseases, DM, chronic liver disease, genetic conditions.

Clinical Manifestations

• Vary widely: asymptomatic infection, mild disease, moderate or severe disease requiring hospitalization, O2 therapy, ICU, mechanical ventilation.

• Large percentage of patients are asymptomatic but can transmit the virus.

• Severe disease (requiring hospitalization) involves pneumonia and associated manifestations (dyspnea, radiographic involvement of more than half of the lung, and/or hypoxia with O2 sats <94%).

• Critical disease includes respiratory failure requiring mechanical ventilation, multiorgan failure, or shock.

Diagnosis

• Nucleic acid amplification testing of respiratory tract secretions (nasopharyngeal swabs).

• Saliva testing for large-scale population screening.

• Lab abnormalities: lymphopenia, thrombocytopenia, elevated inflammatory markers (CRP), elevated LFTs and LDH, elevated markers of AKI, elevated d-dimer and PT, elevated troponin and CK.

• CXR: consolidation and ground-glass opacities bilaterally.

• CT chest: ground-glass opacifications with or without mixed consolidation, pleural thickening, interlobular septal thickening, and air bronchograms.

Treatment

• Antibiotics usually not indicated (bacterial infections are uncommon), but consider empiric antibiotics for CAP if diagnosis is uncertain.

• Pharmacologic prophylaxis for VTE for all hospitalized patients.

• NSAIDs used as antipyretic agents; APAP preferred.

• Antivirals (remdesivir) most effective early; anti-inflammatory meds (steroids) more beneficial later.

Complications

• ARDS, thromboembolic complications (DVT, PE), cardiac complications (MI, arrhythmias, HF), encephalopathy, and seizures.

MERS-CoV

• Associated with a coronavirus similar to SARS.

• History of residence/travel in the Middle East, especially Saudi Arabia, or contact with such patients.

• Transmitted through direct or indirect contact of mucous membranes with infectious respiratory droplets.

• Camels are the principal reservoir; raw camel milk is a potential source.

Clinical Findings

• Acute respiratory syndrome with fever, cough, and dyspnea.

• Chills and rigors are common.

• GI symptoms may occur (diarrhea most common, followed by nausea and abdominal pain).

Diagnosis \& Treatment

• Hematologic findings: thrombocytopenia, lymphopenia, and lymphocytosis.

• Moderate elevations in LD, AST, and ALT.

• CXR: increased bronchovascular markings, patchy infiltrates or consolidations, interstitial changes, opacities, and pleural effusions.

• Serum serologies and RT-PCR available through the CDC.

• Bronchoalveolar lavage fluid, sputum, and tracheal aspirates are preferred samples for diagnosis.

• Treatment: Respiratory support (O2, NIPPV, vent).

• Interferons, ribavirin, lopinavir-ritonavir, or mycophenolate mofetil.

Epstein-Barr Virus (EBV) \& Infectious Mononucleosis (IM)

• EBV causes heterophile-positive infectious mononucleosis (IM): fever, sore throat, lymphadenopathy, and atypical lymphocytosis.

• Associated with nasopharyngeal and gastric carcinoma, Burkitt’s lymphoma, Hodgkin’s lymphoma, T-cell lymphoma, B-cell lymphoma, and smooth muscle tumors.

• Member of the Herpesviridae family.

• Occurs worldwide, most common in early childhood and late adolescence. >90% of adults have been infected and have antibodies.

• IM is a disease of young adults.

• Spread by contact with oral secretions (“kissing disease”).

Symptoms \& Signs

• Most infections in infants and young children are asymptomatic or mild pharyngitis with/without tonsillitis.

• Approximately 75% of infections in adolescents present as IM.

• Incubation period: 4-6 weeks with prodrome of fatigue, malaise, and myalgia for 1-2 weeks before onset of fever, sore throat, and lymphadenopathy.

• Fever is usually low grade and most common in the first 2 weeks of illness.

• Lymphadenopathy (posterior cervical nodes) and pharyngitis are more prominent in the first 2 weeks of illness; splenomegaly is more prominent during the second and third weeks.

• Pharyngitis can be accompanied by enlargement of tonsils with an exudate resembling strep pharyngitis

• Morbilliform or papular rash on arms or trunk develops in 5% of cases.

• IM in the elderly presents with nonspecific symptoms: prolonged fever, myalgia, fatigue, and malaise.

• Severity of disease correlates with levels of CD8+ T cells and EBV DNA in the blood.

• Most patients have symptoms for 2-4 weeks, but 10% have fatigue for >6 months.

Diagnosis \& Treatment

• WBC is usually elevated (10,000-20,000) during the second or third week of illness.

• Lymphocytosis present with >10% atypical lymphocytes.

• Low-grade neutropenia and thrombocytopenia are common during the first month of illness.

• Liver function is abnormal in >90% of cases with elevated serum AST and ALP; serum TB is elevated in approximately 40%.

• Positive heterophile antibody blood test

• Most cases are self-limited

• Deaths are rare and most often due to central nervous system complication, splenic rupture, upper-airway obstruction, or bacterial superinfection.

• Supportive measures, rest, analgesia.

• Avoid physical activity (contact sports especially) during the first month to avoid splenic rupture.

Cytomegalovirus (CMV)

• Caused by Herpesvirus Type 5.

• Most infections are asymptomatic.

• After primary infection, virus remains latent in most body cells.

• Prevalence increases with age and lower socioeconomic status; higher among persons employed in childcare centers.

• Transmission occurs through sexual contact, breastfeeding, blood products, or transplant; may occur person to person (day care centers) or congenital.

• Three recognizable clinical syndromes: perinatal disease and CMV inclusion disease, diseases in immunocompetent persons, and diseases in immunocompromised persons.

• Congenital CMV infection is the most common congenital infection in high-income countries.

• In immunocompetent person, acute CMV infection is the most common cause of the mononucleosis-like syndrome with negative heterophile antibodies.

Clinical Findings

• Perinatal disease and CMV inclusion disease:

  • Infection in newborns: hepatitis, thrombocytopenia, microcephaly, periventricular CNS calcifications, mental retardation, and motor disability.

  • Hearing loss in >50% of infants symptomatic at birth, making CMV a leading cause of pediatric hearing loss.

  • Most infected neonates are asymptomatic, but neuro deficits may occur later, including hearing loss and cognitive impairment.

• Disease in immunocompetent persons:

  • Acute CMV: fever, malaise, myalgias, arthralgias, and splenomegaly.

  • Exudative pharyngitis or cervical lymphadenopathies are uncommon, but cutaneous rashes (including the typical maculopapular rash after ampicillin) are common.

  • Mean duration of symptoms is 7-8 weeks.

• Disease in immunocompromised persons:

  • CMV retinitis: funduscopic exam reveals neovascular, proliferative lesions (“pizza-pie” retinopathy).

  • GI and hepatobiliary CMV: esophagitis with odynophagia; gastritis with bleeding; small bowel disease mimicking IBD; colonic CMV with diarrhea, hematochezia, abdominal pain, fever, and weight loss; CMV hepatitis.

  • Respiratory CMV: CMV pneumonitis with cough, dyspnea, and little sputum production; concomitant infection with PCP.

  • Neurologic CMV: polyradiculopathy, transverse myelitis, ventriculoencephalitis, and focal encephalitis; more prominent in patients with advanced AIDS.

Diagnosis

• Should be tested for viremia every 3 months if found to be seropositive during first trimester.

• Congenital CMV confirmed by virus in amniotic fluid or IgM assay from fetal blood.

• PCR assays, micro-ELISA, shell-vial culture, or culture of urine, saliva, or blood obtained in first 3 weeks of life are used to diagnose congenital CMV infection.

• Acute mononucleosis-like syndrome: leukopenia/ within 1 week followed by absolute lymphocytosis with atypical lymphocytes; abnormal LFTs are common in first 2 weeks.

• Detection of CMV DNA, specific IgM or a 4-fold increase of specific IgG levels supports diagnosis

• CMV retinitis: ophthalmoscopic findings.

• Quantitative DNA PCR of the CSF

• CXR findings consistent with interstitial pneumonia

• Tissue confirmation is useful in diagnosing CMV pneumonitis and CMV GI disease

Treatment

• Immunocompetent patients: infection is self-limited; no specific antiviral therapy is needed.

• Immunocompromised patients: treatment is necessary

  • IV ganciclovir 5mg/kg every 12 hours (adjust for kidney function) until two CMV PCRs 1 week apart are negative

  • Oral valganciclovir 900mg every 12 hours is an alternative in patients without life-threatening disease

  • Foscarnet and cidofovir are reserved for treatment of resistant infections

• No vaccine is available

• Pregnant women with children in childcare need to practice good hand hygiene after diaper changes and after contact with respiratory secretions.

• ART is effective in preventing CMV infections in people living with HIV.

• Primary prevention with hand hygiene and use of barrier methods during sexual contacts with people who are members of high-prevalence groups.

Varicella-Zoster Virus (Shingles)

• Reactivation of latent VZV from dorsal root ganglia.

• Most patients have no history of recent exposure to VZV infection.

• Incidence highest among individuals in their 60s and older.

• Unilateral vesicular dermatomal eruption, often with severe pain. Dermatomes from T3 to L3 are most frequently involved.

• Zoster ophthalmicus results if the ophthalmic branch of the trigeminal nerve is involved.

• Onset heralded by pain within the dermatome which may precede lesions by 48-72 hours.

• Erythematous maculopapular rash evolves rapidly into vesicular lesions. Total duration is 7-10 days but may take 2-4 weeks for skin to return to normal.

• Patients can transmit infection to seronegative individuals, resulting in chickenpox.

Diagnosis \& Treatment

• VZV DNA by PCR; Tzanck smear (scraping of lesion).

• Valacyclovir, acyclovir, famciclovir.

Rabies

• Viral (rhabdovirus) encephalitis transmitted by infected saliva that enters the body by an animal bite or an open wound.

• Virus enters the salivary glands of dogs 5-7 days before their death from rabies, limiting their period of infectivity.

• Less common routes: contamination of mucous membranes with saliva or brain tissue, aerosol transmission, corneal transplantation.

• Incubation period: 10 days to many years (usually 3-7 weeks); depends on the wound’s distance from the CNS.

• Virus travels via nerves to the brain, multiplies there, then migrates along the efferent nerves to the salivary glands.

• Rabies virus infection forms cytoplasmic inclusion bodies similar to Negri bodies.

• In the US raccoons, bats, and skunks accounted for 86.6% of rabid animals in 2018; other rabid animals include foxes, cats, cattle, and dogs.

Signs/Symptoms

• Prodrome: pain at the site of the bite with fever, malaise, headache, nausea, and vomiting; skin is sensitive to changes of temperature, especially air currents (aerophobia), percussion myoedema, and abnormal sexual behavior (priapism and frequent ejaculation in males and hypersexuality in females).

• CNS stage begins 10 days after prodrome with encephalitic or paralytic forms:

  • Encephalitic form (80%): delirium alternating with periods of calm, painful laryngeal spasms on attempting drinking (hydrophobia), autonomic stimulation (hypersalivation), and seizures.

  • Paralytic form: acute ascending paralysis resembling Guillain-Barre syndrome with relative sparing of higher cortical functions initially.

• Both progress to coma, autonomic nervous system dysfunction, and death.

Diagnosis \& Treatment

• Definitive diagnostic assays from the patient’s CSF or saliva

• Antibodies can be detected in the serum and the CSF

• MRI signs are diffuse and nonspecific

• Requires ICU with attention to airway, maintenance of oxygenation, and control of seizures

• Universal precautions are essential

• Corticosteroids are of no use

Ebola

• Genus Ebolavirus is a single-stranded RNA virus in the Filoviridae family.

• Fruit bats are a possible reservoir.

• Zoonotic transmission to humans occurs by contact with reservoir or an infected primate.

• Transmission occurs from direct contact with infected body fluids. Virus must enter the body via mucous membranes, nonintact skin, sexual intercourse, breastfeeding, or needlesticks. Ebola is not transmitted when patients have no symptoms.

• Incubation period: 2-21 days (average is 8-10 days).

• Estimated case fatality rate is 60%.

Signs and Symptoms

• Early stage: headache, weakness, dizziness, fever, malaise, fatigue, myalgia, and arthralgia.

• Later stage (after 3-5 days): abdominal pain, severe nausea, vomiting, diarrhea accompanying febrile illness. May continue for a week.

• Encephalitis is commonly observed and includes confusion, slowed cognition, agitation, occasional seizures.

• Hypovolemic shock develops in most patients.

• Hemorrhagic manifestations develop in only 1-5% of patients.

• Respiratory symptoms (cough) are not typical, although interstitial pneumonia and respiratory failure have been reported.

Diagnostics

• Patient samples are extreme biohazard risks and must be handled with appropriate PPE!

• Tests may be positive during first few days of symptoms:

  • Antigen-capture enzyme-linked immunosorbent assay (ELISA)

  • Immunoglobulin M (IgM) ELISA

  • RT-PCR

  • Virus isolation

• RNA levels peak at a median of 7 days after illness onset.

• Later in the disease course or after recovery, IgM and immunoglobulin G (IgG) serologic tests may be sent

• IgM antibodies begin to develop after about 10 days; IgG antibodies develop after 2 weeks

• Leukopenia; low platelet count

• Hypoalbuminemia; transaminitis (AST>ALT)

• Coagulopathy with evidence of platelet dysfunction and DIC develops as symptoms progress to severe SIRS

• Electrolyte imbalance, increased serum creatinine level

Treatment

• Primarily supportive; IV fluids can reduce mortality rates to <50%!

• Invasive or noninvasive mechanical ventilation and continuous renal replacement therapy are necessary in many cases

• Two monoclonal antibody cocktails (Inmazeb and Ebanga) are approved by the FDA for treatment of infection with Zaire ebolavirus species in adults and children

• Patients typically receive empiric antimalarial agents in endemic areas and broad-spectrum antibiotics

• Complications: hypovolemic shock, multiorgan failure hemorrhage, rhabdomyolysis, coinfections with malaria or bacteria, or both

• Prevention: ZEBOV (Erbevo) is a recombinant vesicular stomatitis virus-based vaccine and is approved by the US FDA. Highly effective in disease prevention 10 days after receiving vaccine.

Pediatric Viruses

Respiratory Syncytial Virus (RSV)

• RNA Pneumovirus

• Spread by airborne droplets

• Most common in children under 5 years of age – most common lower respiratory tract infection

• More common in spring and winter seasons

• Clinical diagnosis primarily but can be confirmed by PCR testing and rapid antigens

• Symptoms: mild cold symptoms and presents uncomplicated; apnea in babies <6 months

  • Rhinorrhea, dyspnea/wheezing, cough, fever

• Treatment = supportive (O2, hydration, antipyretics), antivirals (inhaled ribavirin), high risk → Palivizumab ppx; severe disease →ventilatory support

Erythema Infectiosum (Fifth Disease)

• Main manifestation of symptomatic B19V infection

• Infection begins with a minor febrile prodrome approximately 7-10 days after exposure; the classic facial rash develops several days later; after 2-3 days, the erythematous macular rash may spread to extremities in a lacy reticular pattern.

• Adults usually do not exhibit the “slapped-cheek” phenomenon but present with arthralgia, with or without the macular rash.

• Diagnosis: Detection of B19V IgM antibodies, can be detected at the time of rash. IgG is detectable by 7th day of illness and persists for life.

• Treatment: Symptomatic treatment only.

Measles (Rubeola)

• Highly contagious viral disease characterized by a prodromal illness of fever, cough, coryza, and conjunctivitis followed by a generalized maculopapular rash.

• Spherical, nonsegmented, single-stranded, negative sense RNA virus and a member of the Morbillivirus in the family Paramyxoviridae.

Clinical Findings

• Fever and malaise beginning approximately 10 days after exposure followed by cough, coryza, and conjunctivitis. Signs/symptoms increase in severity over 4 days.

• Koplik’s spots develop on the buccal mucosa approximately 2 days before the rash appears.

• Characteristic rash of measles begins 2 weeks after infection (erythematous macules behind ears and on the neck then spreads to face, trunk, and arms with involvement of legs and feet by the end of the 2nd day), when clinical manifestations are most severe and signal the host’s immune response to the replicating virus. Headache, abdominal pain, vomiting, diarrhea, and myalgia may be present.

Diagnosis \& treatment

• Serology is the most common method of laboratory diagnosis.

• No specific antiviral therapy for measles.

• Treatment consists of general supportive measures, such as hydration and administration of antipyretic agents.

• Prompt antibiotic treatment for patients who have clinical evidence of secondary bacterial infection, including pneumonia and otitis media.

• Vitamin A is effective for the treatment of measles and can markedly reduce rates of morbidity and mortality.

Rubella (German Measles)

• Member of the Matonaviridae family and the only member of the genus Rubivirus.

• Spread from person to person via respiratory droplets.

• Humans are the only reservoir.

• Primary implantation and replication in the nasopharynx are followed by spread to the lymph nodes → viremia.

• In pregnancy, often results in infection of the placenta → infection of fetal organs.

• Individuals with acquired rubella may shed virus from 7 days before rash onset to approximately 5-7 days after.

• Presents as a generalized maculopapular rash that lasts for up to 3 days.

• Rash is usually mild and may be difficult to detect with darker skin.

• In children, rash is usually first sign of illness. In older children & adults, a 1-5 day prodrome often precedes the rash (low-grade fever, malaise, and URI symptoms).

• Incubation period is 14 days.

• Both clinical and subclinical infections are considered contagious.

Diagnosis \& Treatment

• Serologic diagnosis is most common

• No specific treatment; supportive → treat the symptoms

Varicella Zoster Virus (Chickenpox)

• A ubiquitous and extremely contagious infection, is usually a benign illness of childhood characterized by an exanthematous vesicular rash.

• Historically, children 5-9 years old were the most commonly affected.

• A member of the family Herpesviridae

• Transmission occurs by the respiratory route → replication of virus leads to seeding of the lymphatic/reticuloendothelial system → viremia.

• Humans are the only known reservoir for VZV.

• Both sexes and all races are infected equally.

• Incubation period is 10-21 days, but usually 14-17 days.

• Patients are infectious approximately 48 hours before onset of rash, during vesicle formation (lasts approximately 4-5 days), and until all vesicles are crusted.

Clinical Findings

• Rash, low grade fever, and malaise.

• Skin lesions (hallmark of infection!) include maculopapules, vesicles, and scabs in various stages of evolution.

• Lesions evolve from maculopapules to vesicles over hours to days, appear on trunk and face, and rapidly spread to other areas of the body. Most are small on an erythematous base with diameter of 5-10mm. Can be found on the mucosa of the pharynx and/or vagina.

DiagnosisTx

• Isolation of VZV in susceptible tissue-culture cell lines

• Demonstration of either seroconversion or a 4-fold or greater rise in antibody titer between acute-phase and convalescent-phase serum specimens

• Detection of VZV DNA by PCR in skin lesions, blood, or saliva.

• Tzanck smear → sensitivity is low (approximately 60%)

Treatment

• Good hygiene including daily bathing and soaks

• Crop fingernails to avoid secondary bacterial infection

• Pruritis can be decreased with topical dressings or antipruritic drugs

• Tepid water baths and wet compresses

• Acyclovir, valacyclovir, or famciclovir for 5-7 days in adolescents and adults <24 hr duration

• Acyclovir therapy for children <12 years of age if started early in disease

Viral Diseases, Part 2

Avian Influenza

• Birds are the natural hosts

• Avian influenza A = outbreaks occur in poultry occasionally; virus has become endemic in poultry mostly in Southeast Asia and Egypt.

• Occasionally, avian influenza viruses may infect humans or other mammals, including domestic cats and dogs.

• Illness in humans ranges from mild disease to rapid progressive severe disease and death depending on the subtype.

• Risk factors for human infection: direct or indirect exposure to infected live or dead poultry or contaminated environments (live bird markets), slaughtering and handling carcasses of infected poultry.

• Virus subtypes in humans: H5, H7, and H9 avian influenza

• Average global case fatality rate of 40%

Clinical Findings

• Symptoms and signs

  • Fever, lower respiratory symptoms (cough and dyspnea); upper respiratory tract symptoms are less common, GI symptoms are reported more frequently in H5N1 infections, conjunctivitis in flu H7 infections.

  • Other symptoms can also be involved leading to neurologic manifestations (encephalopathy, seizure) and liver impairment, prolonged febrile states and generalized malaise are common, and bacterial superinfection is reported.

Diagnostics

• real-time reverse transcriptase-polymerase chain reaction (RT-PCR) are most sensitive

• Initial negative result when clinical suspicion remains high, repeat testing is warranted

• Throat swabs or lower respiratory specimens provide a higher yield detection than nasal swabs

Treatment

• Oseltamivir → first line, 75mg BID x 5 days started within 48 hrs of illness onset

• Consider a longer course (10 days) for hospitalized patients with severe illness

• Peramivir → for patients who cannot take oral therapy; 600mg daily IV x 5-10 days. Reduce dose to 200mg IV daily for kidney dysfunction.

• Zanamivir 10mg inhaled daily x 10 days is another possible alternative.

• Combo therapy with amantadine or rimantadine may be considered for PNA or progressive disease.

• Supportive measures with adequate hydration, analgesics, O2, and rest

Hantavirus Infections

• Hantaviruses are RNA bunyaviruses transmitted by rodents.

• They cause two main syndromes: Hemorrhagic Fever with Renal Syndrome (HFRS) and Hantavirus Pulmonary Syndrome (HPS).

• These infections affect over 200,000 people annually with a 35-40% mortality rate mortality rate globally.

Transmission and Risk Factors

• Hantaviruses are hosted by rodents, rodents, moles, and shrews.

• Transmission occurs through aerosols aerosols of virus-contaminated urine urine and feces.

• Old World hantaviruses (Asia/Europe) (Asia/Europe) cause HFRS. New World hantaviruses (Americas) cause cause HPS.

• Animal trappers, forestry workers, laboratory personnel, farmers, and military personnel face higher exposure risk.

Clinical Manifestations

• HFRS Progression

  • 2-3 week incubation followed by febrile period, hypotension, oliguria, diuresis, and convalescence.

  • Renal involvement is primary.

• HPS Progression

  • 14-17 day incubation followed by prodromal phase with myalgia and myalgia and fever. Progresses to pulmonary edema and myocardial myocardial depression.

• Laboratory Findings

  • Both show hemoconcentration, thrombocytopenia, leukocytosis, and leukocytosis, and elevated enzymes.

  • HPS may show immunoblasts in immunoblasts in multiple organs.

Diagnosis and Treatment

• Diagnostic Tests

  • Immunoassays detect IgM or IgG antibodies.

  • RT-PCR available but available but limited by short viremia.

• Supportive Care

  • Primary treatment is supportive.

  • Cardiorespiratory support with vasopressors often needed.

• Antiviral Therapy

  • Intravenous ribavirin may help in HFRS by decreasing kidney injury kidney injury severity.

  • Effectiveness in HPS not established.

Dengue Fever

• Dengue is a mosquito-borne viral disease endemic in over 100 countries.

• Four Four distinct serotypes can cause infection.

• Most infected patients are asymptomatic, but 20% develop symptoms ranging from mild to severe.

Diagnosis and Clinical Presentation

• Incubation Period

  • 7-10 days before symptoms appear

• Initial Symptoms

  • Sudden high fever, chills, myalgias, headache, retro-orbital pain

• Progression

  • Possible plasma leakage, hemorrhage, or organ involvement

• Severe Manifestations

  • Ecchymoses, gastrointestinal bleeding, epistaxis appear later

Laboratory Findings

• Leukopenia

• Elevated transaminases

• Thrombocytopenia in hemorrhagic form

• IgM and IgG ELISAs after febrile phase

• PCR or NS1 detection during first days

• Platelet count

• Serum albumin

• AST and ALT levels

Treatment and Management

• Appropriate fluid therapy is the cornerstone of management

• Acetaminophen recommended; avoid NSAIDs to prevent bleeding

• Consider platelet transfusions for severe thrombocytopenia (<10,000/mcL)

• Vasopressors may be needed for dengue shock syndrome

Chikungunya Fever

• Chikungunya fever, named from the Kimakonde phrase meaning

There is no additional information provided in the document after the Viral Diseases, Part 2, section. The note ends with Chikungunya Fever.