diease

HIV-Human Immuno Deficiency Virus


HIV-Human Immuno Deficiency Virus overview and Definition

HIV is a virus that targets the immune system and alters it. Without treatment, the infection leads to an advanced stage called as AIDS.

A.Terminology Description

   HIV stands for Human Immunodeficiency Disorder. If left untreated HIV causes AIDS that stands for Acquired Immuno-deficiency Syndrome.

B.Clinical Clarification/Definition

   Once a person is infected with HIV they become vulnerable to several infections and cancers or tumors due to weakened immune system mainly white blood cells the CD4+ Tcells. The final stage of HIV infection is AIDS. It is important to understand that not everyone infected with HIV develop AIDS. Once a person is infected with HIV there is no effective treatment that may cure them but rather certain medications control the infection and improves the immunity of the infected person.

C.Classification

HIV is caused by a virus belonging to genus Lentivirus a part of retroviridae.

     There are 2 types of HIV infections:

     HIV 1 - This is a more common type. It is more virulent and highly infective thus when exposed to virus 95% of the people contract the infection.

     HIV 2 is less infective thus when exposed only 55% of the people contract the infection

   Based on CD4+ T Cell levels HIV can be staged as

     Primary HIV infection: asymptomatic

     Stage I: HIV infection is asymptomatic with a CD4+ T cell count >500 per microlitre of blood and generalised lymphadenopathy

     Stage II: Mild symptoms, like minor mucocutaneous manifestations and recurrent upper respiratory tract infections with CD4 count of < 500/µl

     Stage III: Advanced symptoms, like chronic diarrhea for >1 month, severe bacterial infections like TB, with CD4 count of <350/µl

    Stage IV or AIDS: severe symptoms, like toxoplasmosis of the brain, candidiasis of the esophagus, trachea, bronchi, or lungs, and Kaposi's sarcoma with CD4 count < 200/µl

D.Epidemiology

   In 2017, according to epidemiological case study 2.1 million people were identified to be infected with HIV. 0.2% of HIV infected population are between ages 15 – 49. Annual raise in cases is 88,000. Only 56% of infected HIV population is on antiretroviral treatment. 69,000 people have died due to HIV annually in India. Amongst this population 76% were men and 24% were women, 75% of the infected population were due to men-to-men sexual contact, 14% were heterosexual, 8% were due to drug users.


Pathophysiology

HIV is a virus that attaches to host T cells and penetrates them through CD4+ T cells and chemokine receptors. After attachment, HIV RNA and other HIV-encoded enzymes are released into the host cell. Viral DNA enters host cell’s nucleus and integrates into host DNA by integrase. With each cell division, the integrated DNA is duplicated with host DNA and transcribed to HIV RNA and translated to HIV proteins, like envelope glycoproteins 41 and 120. These HIV proteins are assembled into HIV infective virions.


Clinical signs & symptoms

A.Asymptomatic HIV infection

   This period may vary from months to years

B.Acute HIV infection

   this period may vary from 1 – 4 weeks. Most commonly found symptoms are Fever with rash, pharyngitis with lymphadenopathy, myalgia or arthralgia, headache and mucosal ulceration. Other symptoms are as follows:

  • General symptoms – fever, pharyngitis, lymphadenopathy, headache, retroorbital pain, arthralgia, myalgia, lethargy, malaise, anorexia, weight loss, nausea, vomiting, persistent diarrhea
  • Neurological – meningitis, encephalitis, peripheral neuropathy, myelopathy
  • Dermatological – erythematous maculopapular rash, mucocutaneous ulceration

 

C.Symptomatic HIV infection

   this phase occurs when CD4+T Cells is <200/uL. It causes

  • Persistent generalised lymphadenopathy – palpable lymphadenopathy in more than 2 extra inguinal sites for more than 3 months
  • Constitutional symptoms – fever persisting >1 month and weight loss >10%
  • Neurological diseases – HIV Associated Neurocognitive Diseases, primary CNS lymphoma, CNS Kaposi sarcoma, aseptic meningitis, myelopathy, peripheral neuropathy and myopathy
  • Secondary infectious diseases – Pneumonia, CMV related diseases, Candida related diseases, bacterial and fungal infections
  • Secondary neoplasm – Kaposki sarcoma and lymphoma

 


Differential Diagnosis

I.Clinical Examination/tests

  • General – fever, lipodystrophy, night sweats
  • Skin - Fat loss, Dermatitis
  • Oral cavity – Periodontitis, Aphthous ulcers
  • Head and neck - Enlarged lymph nodes, Buffalo hump, Neck stiffness
  • Eyes – Conjunctivitis, retinitis
  • Neurological - Dementia
  • Chest cavity – Crepitations, tachypnoea, breathlessness, dry cough
  • Abdomen cavity – hepatosplenomegaly, fat gain
  • Anogenital – rash, condyloma
  • Limbs – spastic paraparesis, peripheral neuropathy, fat loss

 

II.Laboratory tests

  • Standard screening method is Enzyme Immuno assay which is highly sensitive and specific. It detects antibodies of HIV 1 and 2
  • Western Blot is the most commonly used confirmatory test which tests antibodies to HIV antigens from 18th day after exposure
  • Incase of indeterminant EIA and Western blot, RT-PCR can be done
  • Viral P24 antigen which disappears within 10 weeks post exposure
  • Within 10 days to exposure Nucleic acid amplification test is done
  • Peripheral Blood or Plasma culture

 

General instruction:

If ELISA test is negative after confirmed exposure or in a high risk person, repeat test after 3 months.

If test report is positive confirm the report with western blot or EIA.

In case of vertical transmission Nucleic acid amplification test is done

The following tests are done after confirmation of HIV markers,

  • CD4+ T Cell count <200/uL – more susceptible to Pneumocyctitis jiroveci and <50/uL is more susceptible to Mycobacterium Avium
  • Viral load
  • Positive markers of hepatitis C or B
  • Plasma HIV RNA – used in choosing ART
  • Screening for STD’s – cervical pap smear, toxoplasmosis, CMV, treponema
  • CBC – thrombocytopenia, lymphopenia
  • Stool analysis – ova, cyst and parasites
  • Blood culture for mycobacterium

 

III.Imaging

    CT/MRI

  •      diffuse cerebral atrophy
  •      basal ganglia calcification
  •      pseudocyst
  •      brain lymphoma
  •      Kaposi sarcoma
  •     Pneumonia

 Chest X ray

  •     Pneumonia
  •    ground glass appearance
  •    mediastinal shift
  •    lymphadenopathy
  •    solitary nodules
  •   dilated cardiomyopathy

  HRCT

  • pneumonia and pulmonary cyst
  • ground glass appearance

 Echocardiogram

  • dilated cardiomyopathy
  • pericardial effusion
  • pulmonary hypertension
  • MI

Barium swallow

  • shaggy esophagus in candida infection
  • diffuse thickening of bowel

ERCP

  • acalculous cholecystitis
  • cholangitis

DIFFERENTIAL DIAGNOSIS:

  • Kaposi's sarcoma
  • Tuberculosis
  • non-Hodgkin lymphoma
  • Cryptococcus or pyogenic bacterial pneumonia


Prevention

  • Education, Counselling, and Behaviour modification with correct use of condoms to ensure safer sex
  • Avoid sharing needles
  • Avoid breast feeding
  • Male circumcision to avoid heterosexually transmitted disease
  • Use of antiretroviral containing vaginal gels
  • Take pre exposure antiretrovirals for male and female
  • Take post exposure prophylaxis