Medicine Marrow Pg No 1055-1064 (Infectious Diseases)

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Questions and Answers

What is the primary function of the CD4 receptor in HIV viral replication?

Protecting the host cell

Binding to gp120 (correct)

Binding to viral RNA

Facilitating viral release

During viral integration, viral DNA remains separate from the host DNA.

False

What happens to immature virions during the viral proliferation and release stage?

They get cleaved by protease to become mature viruses.

In the primary infection stage, clinical symptoms may include fever, sore throat, and __________.

diarrhea Signup and view all the answers

Match the following HIV replication stages with their descriptions:

Viral entry = Initiation of virus binding to host cell Reverse transcription = Conversion of viral RNA to DNA Viral integration = Integration of viral DNA into host genome Viral proliferation and release = Formation of immature virions and their maturation Signup and view all the answers

What is the characteristic feature of scrub typhus?

Eschar Signup and view all the answers

Malaria involves a phase where sporozoites turn into merozoites in the liver.

True Signup and view all the answers

What is the infectious agent responsible for scrub typhus?

Orientia tsutsugamushi Signup and view all the answers

The treatment for scrub typhus may include ________ 100mg BD for 7 days.

Doxycycline Signup and view all the answers

Match the following diseases with their clinical features:

Scrub Typhus = Sensorineural deafness Malaria = Sporozoites as infective form Signup and view all the answers

What is a potential consequence of decreased platelet count in patients during the crucial period of infectious diseases?

Bleeding Signup and view all the answers

Capillary leak syndrome can lead to pleural or pericardial effusion.

True Signup and view all the answers

What is the primary focus during the management of patients in the critical days of infectious diseases?

Monitoring and maintenance of vital signs. Signup and view all the answers

During the management of dengue with warning signs, intravenous (IV) fluids are used to maintain blood pressure and monitor __________ diameter.

IVC Signup and view all the answers

Match the following conditions with their associated symptoms:

Decreased platelet count = Bleeding Capillary leak syndrome = Ascites Dengue warning signs = Organ failure IV fluids = Blood pressure maintenance Signup and view all the answers

What is a major complication associated with P. falciparum malaria?

Non-cardiogenic pulmonary edema Signup and view all the answers

Duffy negative RBCs provide protection against P. falciparum.

False Signup and view all the answers

What receptor does the malaria parasite bind to on red blood cells?

glycophorin A Signup and view all the answers

In complicated malaria due to P. falciparum, the patient may experience ________ due to anaerobic metabolism.

acidosis Signup and view all the answers

Match the following Plasmodium species with their ability to cause relapses:

P. falciparum = No P. vivax = Yes P. ovale = Yes P. malariae = No Signup and view all the answers

Which gene is responsible for coding the spike protein in HIV?

Env Signup and view all the answers

HIV can only be transmitted through sexual contact.

False Signup and view all the answers

What is the maximum risk percentage for acquiring HIV during delivery?

20-30% Signup and view all the answers

The primary enzyme coded by the Pol gene is __________.

reverse transcriptase Signup and view all the answers

Match the following modes of transmission with their corresponding HIV exposure risk levels:

Blood transfusion = Maximum risk Needle stick = High risk IV drug abuse = Moderate risk Sexual contact = Variable risk Signup and view all the answers

What year was the first reported case of HIV?

1981 Signup and view all the answers

World AIDS Day is observed on November 1st.

False Signup and view all the answers

Who isolated the HIV virus in 1983?

Luc Montagnier Signup and view all the answers

The term AIDS was coined by the CDC in ______.

1982 Signup and view all the answers

Match the following stages of HIV with their clinical evidence:

Stage 0 = No AIDS-defining condition Stage 1 = No AIDS-defining condition Stage 2 = CD4 count between 200-499 cells/mm³ Stage 3 = AIDS-defining condition present Signup and view all the answers

What is considered the gold standard for malaria diagnosis?

Thick smear Signup and view all the answers

Rapid diagnostic tests for malaria using HRP2 are fully validated.

False Signup and view all the answers

What is the first-line treatment for uncomplicated malaria?

Artemether 20mg + Lumefantrine 120mg Signup and view all the answers

The QBC test for malaria utilizes ______ as the stain.

Acridine orange Signup and view all the answers

Match the following treatments to their corresponding types of malaria:

Oral therapy = Artemether + Lumefantrine IV therapy = Artesunate Doxycycline + Quinine = Uncomplicated Malaria Atovaquone + Proguanil = First line treatment Signup and view all the answers

What is the gold standard test for diagnosing leptospirosis?

Microscopic agglutination test (MAT) Signup and view all the answers

Conjunctival congestion is a feature typically associated with leptospirosis.

True Signup and view all the answers

What are the two main components of hepatorenal syndrome in leptospirosis?

Hepatitis with jaundice and Acute tubular necrosis Signup and view all the answers

The incubation period for leptospirosis is typically ________ days.

10 Signup and view all the answers

Match the complications with their descriptions:

Hepatorenal syndrome = Hepatitis with jaundice + Acute tubular necrosis Thrombocytopenia = Low platelet count Myocarditis = Inflammation of the heart muscle Aseptic meningitis = Inflammation of the protective membranes of the brain Signup and view all the answers

Which of the following is a chronic intestinal parasite infection lasting more than one month?

Cryptosporidiosis Signup and view all the answers

Mycobacterium tuberculosis is classified as an AIDS-defining illness.

False Signup and view all the answers

What was the first case of HIV detected in India?

1986 in Chennai Signup and view all the answers

The exterior of the HIV structure is labeled as the ______, composed of glycoprotein gp41 and gp120.

envelope Signup and view all the answers

What is the primary treatment for uncomplicated cases of Salmonella infection?

Cotrimoxazole (DS) BD for 14 days Signup and view all the answers

Match the following HIV-1 groups with their characteristics:

Group M = Most common group Group N = Less common group Group O = Limited geographic distribution Group P = Recently discovered Signup and view all the answers

The NS-1 antigen remains positive from Day 1 until the end of the dengue disease course.

False Signup and view all the answers

What is the incubation period for dengue?

7-10 days Signup and view all the answers

Salmonella invades and multiplies in the __________ system of the bowel.

lymphatic Signup and view all the answers

Match the following symptoms with their corresponding days in dengue disease course:

High grade fever = Day 1 to 3 Fever subsides = Day 4 onwards Headache = Day 1 to 3 ↓ Platelet counts = Day 4 onwards Signup and view all the answers

Study Notes

Viral Replication Steps

Viral entry occurs when gp120 on the virus binds to the CD4 receptor on lymphocytes.
gp120 undergoes a conformational change, allowing co-receptor binding to CXCR4 (lymphocytes) or CCR5 (macrophages).
gp41 undergoes a conformational change, leading to fusion and uncoating of the virus.
Reverse transcription converts viral RNA into DNA.
Viral DNA integrates into host DNA.
Viral RNA creates viral proteins, leading to the formation of immature virions on the cell surface.
Mature virus is released after cleavage by protease.

Disease Progression

Primary infection: Incubation period of 3-6 weeks.
Acute infectious syndrome/Acute HIV infection: Fever, sore throat, diarrhea, lymphadenopathy, and rash.
90% of patients experience resolution of symptoms.
10% experience a fulminant stage (meningoencephalitis).
Establishment of infection in the gastrointestinal tract (GALT).
Subclinical replication occurs for a long period (clinical latency).

Scrub Typhus

Infectious agent: Orientia tsutsugamushi.
Endothelial proliferation leads to loss of endothelial integrity.
Micro infarcts occur in the kidneys, leading to acute tubular necrosis and a thrombotic microangiopathic pattern.
Eschar is a characteristic feature.
Lymphadenopathy develops after one week.
Untreated cases can lead to CNS involvement within one week, presenting with sensorineural deafness (reversible) and opsoclonus, myoclonus.

Malaria

Sporozoites are the infective form of the parasite.
Sporozoites travel through the blood to the liver and undergo pre-erythrocytic schizogony.
Fever and rupture of red blood cells occur, releasing merozoites that undergo erythrocytic schizogony.
Merozoites are released into the bloodstream, continuing the cycle.

Clinical Features of Malaria

High-grade fever with chills and rigors.
Extreme fatigue.

Complications of Malaria

Sequestration of infected red blood cells in vital organs causes organ ischemia.

Miscellaneous Information about Malaria

Parasites bind to glycophorin A receptors on red blood cells.
Duffy-negative red blood cells provide protection against P.vivax.
Sequestration of red blood cells within vital organs is caused by cyto-adherence, rosetting, and agglutination of red blood cells.
Sickle cell trait and G-6PD deficiency protect against P.falciparum.
The spleen is the major organ involved in trapping red blood cells.

Characteristics of Plasmodium Species

P. falciparum: 48-hour erythrocytic cycle, younger cell preference, black pigment, no relapses.
P. vivax: 48-hour erythrocytic cycle, reticulocytes and younger cells, yellow-brown pigment, relapses possible.
P. ovale: 50-hour erythrocytic cycle, reticulocytes, dark-brown pigment, relapses possible.
P. malariae: 72-hour erythrocytic cycle, older cells, brown-black pigment, no relapses.

Uncomplicated Malaria

Fever with chills, fatigue, and diaphoresis.
Tachypnea, tachycardia, and splenomegaly.
Myalgia (not severe).

Complicated Malaria

Anemia.
Acidosis (lactic acidosis due to anaerobic metabolism).
Renal failure (due to red blood cell sequestration).
Non-cardiogenic pulmonary edema (ARDS).
Jaundice.
Cerebral malaria (convulsions, seizures).
Hypoglycemia.
Hypotension/shock.
Hemoglobinuria (black water fever).

HIV Structural Genes

Env: Codes for gp160 (spike protein).
Gag: Codes for gp41 (transmembrane pedicle protein).
Pol: Codes for enzymes (reverse transcriptase, integrase, protease).
Other Genes: p17, gp41, matrix protein, core protein, nucleocapsid protein.

HIV Non-Structural Genes

Nef/p2: Negative effector that downregulates host CD4 cells.
Vif: Viral infectivity factor.
Rev: Regulation of viral expression.
Tat: Transcription activator.
Vpr: Viral protein R.
Vpu/vpx.

HIV Infection Sources

High Concentration: Blood, semen, vaginal fluid, pus from sores, cerebrospinal fluid (CSF).
Low Concentration: Sweat, tears, urine, saliva (SLIP: Salivary lymphocyte inhibitory protein), breast milk.

Modes of Transmission

Sexual.
Parent to child.
Intravenous drug abuse.
Blood transfusion.
Needle stick.

Risk of Acquiring HIV per 10,000 Exposures

Maximum: Blood transfusion (9250/10,000).
Parent to child.
Intravenous drug abuse.
Needle stick.

Maximum Risk in Pregnancy

During delivery (20-30%).

Note on HIV

Delta32 mutation in the CCR5 receptor on macrophages renders resistance to HIV infection.
DC sign refers to C-type lectin receptors on dendritic cells that bind to HIV.

Leptospirosis & Scrub Typhus

Transmission Agent: Rodents.
Incubation Period: 10 days.

Clinical Presentation of Leptospirosis

Abrupt onset fever (low to intermediate grade).
Myalgia.
Calf muscle tenderness.
Conjunctival congestion.

Complications of Leptospirosis

Hepatorenal syndrome: Hepatitis with jaundice and acute tubular necrosis.
Thrombocytopenia.
Myocarditis.
Secondary mitral regurgitation/aortic regurgitation.
Aseptic meningitis.

Diagnosis of Leptospirosis

Modified Faine's criteria.
Gold standard test: Microscopic agglutination test (MAT).
Lepto IgM ELISA positive after 7 days.

Treatment of Leptospirosis

Doxycycline + Inj. Ceftriaxone 2g IV OD.

Diagnosis of Malaria

Microscopy: Thick smear is the gold standard, using Giemsa staining and light microscopy. Thin smear is not sensitive.
QBC test: Uses acridine orange stain for detection, three tests are conducted 12 hours apart.
Rapid diagnostic test: HRP2 (not validated).

Treatment of Malaria

Uncomplicated Malaria (Oral therapy): Artemether 20mg + Lumefantrine 120mg (first line), 4 tablets BID x 3 days. Alternative regimens include Atovaquone + Proguanil, Clindamycin + Mefloquine, Doxycycline + Quinine, Artesunate + Amodiaquine, Artesunate + Mefloquine.
Complicated Malaria (IV therapy): Day 1: Three doses of IV Artesunate (120mg/2.4mg per kg) at 0, 12, and 24 hours. Day 2 and 3: Single dose of 2.4 mg/kg.

HIV History

First reported case: 1981.
AIDS (Acquired Immunodeficiency Syndrome) term coined by CDC: 1982.
First isolation of the virus: 1983 by Luc Montagnier and colleagues, named as Lymphadenopathy Associated Virus (LAV) from an African patient.
World Aids Day: 1 December (since 1987).

CDC Staging of HIV Infection

Stage	CD4 count	CD4 %	Clinical evidence
Stage 0	≥500 cells/mm³	≥26	No AIDS-defining condition
Stage 1	200-499 cells/mm³	14-25	No AIDS-defining condition
Stage 2	100-199 cells/mm³	5-13	No AIDS-defining condition
Stage 3	<100 cells/mm³	<5	At least one AIDS-defining condition
Stage 4	<100 cells/mm³	<5	AIDS

Pathogenesis of Salmonella

Transmission: Feco-oral route.
Salmonella invade the small intestine through the bloodstream (WBC).
Salmonella multiply in the liver, spleen, and bone marrow, re-entering the bloodstream.
Invasion and multiplication occur in the gallbladder, biliary system, and lymphatic system of the bowel.
Salmonella pass into the intestinal tract, causing ileocoecal hyperplasia.

Treatment of Salmonella

Uncomplicated cases: Cotrimoxazole (DS) BD x 14 days, or Azithromycin 1g OD x 7 days.
Complicated cases: Ceftriaxone 2g IV OD x 14 days.

Dengue

Incubation period: 7-10 days.

Disease Course of Dengue

Day 1-3: NS-1 antigen positive. Symptoms include high-grade fever, headache, retro-orbital pain, and vomiting.
Day 4 onwards: NS-1 antigen negative. Symptoms include subsiding fever, decreased platelet counts, and potential for dengue with warning signs/organ failure.

Active Space (Opportunistic Infections)

Parasites: Cryptosporidiosis (chronic intestinal > 1 month), Isosporiasis (disseminated or extrapulmonary), Toxoplasmosis of the brain.
Bacterial infections: Mycobacterium avium complex, Mycobacterium tuberculosis, Salmonella septicemia.

Features of HIV in India

First case detected (Chennai): 1986.

Retroviridae Family

Delta virus: HTLV-I, responsible for adult T-cell lymphoma/leukemia and tropical spastic paraparesis.
Lentivirus Serotypes: HIV-1 and HIV-2.

HIV-1 Groups

M (most common).
N.
O.
P (total: 10). Most common subtype: C. Subtype B spreads through blood and homosexuals.

HIV-1 Structure

Envelope: Composed of glycoproteins gp41 and gp120.
Nucleocapsid: Contains RNA, protease, reverse transcriptase, integrase, and p17.

HIV-2

Less virulent.
Belongs to the simian viridae family.
West African virus.

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This quiz covers the steps involved in viral replication, including viral entry, reverse transcription, and integration into host DNA. It also examines the progression of HIV disease from primary infection to clinical latency and acute symptoms. Test your understanding of these crucial biological processes.