Once infected with HIV (Human Immunodeficiency Virus), the person’s immune system is weakened or damaged by the virus. It may take up to 5 to 10 years for this damage to take serious effect. That is when AIDS (Acquired Immunodeficiency Syndrome), and the ensuing opportunistic infections develop.

This is the period when the complications and effects of HIV/AIDS begin to be seen in the HIV-positive person and opportunistic infections set in.

Once the immune system is damaged, the person becomes very vulnerable to diseases caused by various bacteria, viruses, fungi, and parasites, which otherwise will not overcome the immune system in a healthy person. This is the reason why HIV leads to opportunistic infections.

These infections set in and form the complications of HIV and AIDS, which ultimately kill the patient.

What is an HIV opportunistic infection? Definition

An opportunistic infection is a disease that develops in a person with a compromised immune system. Such infections are typically seen in an HIV-infected person whose immunity is damaged by the HIV.

Using the opportunity of the weak immunity of the infected person, various bacteria, viruses, fungi, and parasites attack and cause infections, which can result in the death of the person. Such a person is also very likely to develop certain cancers. These infections are labeled opportunistic infections of HIV and herald the onset of AIDS.

CD4 or the T cells are the important cells of our immune system. These are the cells that the HIV virus damages and kills and which ultimately cripple the immune system of the infected person.

When the immunity of the infected person is substantially damaged, certain infections take this opportunity to invade the body and cause diseases.

These opportunistic infections of  AIDS are said to develop when the CD4  T- cell count falls below 200 per microliter of blood, but more so below 100 per microliter of blood.

This is when the immune system is very badly damaged and is unable to protect the body from infectious agents. The normal CD4 count is 500 to 1200 per microliter of blood.

However, antiretroviral therapy (ART) suppresses the multiplication and growth of the virus and can prevent or delay the complications by decades. ART is not just about medicating the patient but also involves the management of their side effects and monitoring the patient’s response to the therapy.

Some doctors also advise alternative medicine and counseling, which helps you to live with your condition.

Though complications set in after the CD4 count falls below 200 mm3, ART is started prophylactically when the count falls to 350 mm3. A healthy lifestyle also plays a major role to delay immunity damage.

Common opportunistic infections of HIV/AIDS and their CD4 count

Opportunistic infections involve most systems in the body, mainly the respiratory system, the nervous system (brain), the gastrointestinal tract, the eyes, the muscles, the skin, and the lymphatic system. The organisms that cause the diseases include bacteria, viruses, fungi, and parasites.

I have explained the causative organisms, symptoms, diagnostic tests, and treatments in brief. But, I would strongly suggest that you also read the World Health Organization’s (WHO) guidelines for the management of opportunistic infections in adults and adolescents. 

Respiratory infections: Bacterial and Fungal

  • Pneumocystis Jiroveci Pneumonia.  This is a serious infection also known by the name Pneumocystis Carinii Pneumonia (PCP) and is caused by a fungus called Pneumocystis jirovecii. This fungus spreads through the air and healthy people exposed to it easily fight it off. But, in an HIV-positive person with a damaged immune system, this infection causes PCP. This is the most common opportunistic infection seen in 30% to 40% of AIDS patients in the United States. Symptoms include a dry cough, shortness of breath, fever, malaise, weakness, pain in the chest, and weight loss. It is difficult to diagnose this condition clinically and requires special tests, which can confirm its presence. Treatment consists of a sulfamethoxazole/trimethoprim combination. This may be also associated with tuberculosis, other fungal infections, and Kaposi’s sarcoma.
  • Recurrent bacterial pneumonia. Studies indicate that people with immunosuppression caused by HIV are at an increased risk of catching bacterial pneumonia, which may recur more than two times a year. Pneumonia is fairly common but in a person with recurrent episodes, AIDS should be ruled out. X-ray findings may be atypical and may show diffuse infiltrates.
  • Pulmonary Tuberculosis. 90% of healthy people will not develop active tuberculosis when exposed to the TB bacteria. But tuberculosis (TB) is another most common opportunistic infection seen in patients with HIV. It is the leading cause of death among patients who have developed AIDS.  HIV-positive persons are ten times more likely to develop tuberculosis than healthy persons. The tuberculosis bacteria are airborne and one is likely to get TB after constant exposure to a TB patient, who releases the bacteria into the air on coughing or sneezing. This infection is more likely when one is working in a crowded or an ill-ventilated room. It is more common in underdeveloped countries. Symptoms of pulmonary tuberculosis include low-grade fever more at night with chills, cough with phlegm, which can be blood stained, loss of appetite and weight, and weakness. Tuberculosis can infect any organ of the body but pulmonary tuberculosis (of the lungs) is the most common. It accounts for 40% of opportunistic infections in HIV-positive patients. Diagnosis tests include blood tests to check for a high ESR, chest X-ray, and sputum culture. Treatment of tuberculosis in an HIV-positive patient can be tricky because ART and anti-tuberculosis drugs interact with each other. Depending on the CD4 count, the doctor will decide to put the patient on ART or anti-TB drugs. However, preventive therapy for TB can be started on HIV-positive patients irrespective of whether he or she is on ART. This consists of Isoniazid and cotrimoxazole. It helps in reducing the incidence of infection and death due to TB in children.
  • Mycobacterium Avium Complex (MAC). Mycobacterium Avium Complex is a bacterial complication of HIV, which is found in the late stages of AIDS and when the CD4 count has fallen below 50 per mm3. This group of bacteria is found in food, water, and soil and they are generally present in the body subclinically. It is when the immune system is weakened as in an HIV-positive patient that this infection manifests itself clinically. This infection can be localized in the lungs, bone, or intestines or it can spread throughout the body when it is called a disseminated infection. Disseminated MAC symptoms include fever with chills, diarrhea, abdominal pain, loss of weight, weakness, and anemia. Other complications due to localized infection can occur such as pneumonia. Diagnosis is with a culture of blood, urine, bone marrow, and a biopsy of infected tissue. Treatment is with a combination of antibiotics with either clarithromycin or azithromycin along with drugs used in anti-tuberculosis therapy such as Myambutol and rifampicin. These drugs do interact with ART and it rests with the doctor what treatment to continue first.

Nervous System opportunistic complications: parasitic, viral and fungal

In the United States, neurological complications of AIDS are seen in about 50% of the cases.

  • Cerebral Toxoplasmosis. Toxoplasmosis is caused by the parasite, toxoplasma gondii, which is found in cat feces, contaminated water, and undercooked meat especially of venison (deer meat), lamb, and pork. It occurs due to the activation of cysts in the brain resulting in multiple localized abscesses. It is seen in healthy people too but is kept under control by the healthy immune system, and symptoms are not seen. According to the Centers for Disease Control and Prevention (CDC) (2011), over 60 million people in the United States are infected with this parasite. It is an opportunistic infection, which affects HIV-positive people, especially those in whom the CD4 count has dropped below 100 mm3 and the immune system is pretty much compromised. It is more commonly seen in underdeveloped countries. Though more common earlier, it is seen less now because of the advent of antiretroviral therapy. Clinically, neurological symptoms include a headache, confusion and drowsiness, seizures, focal weakness, and speech disturbance. The patient may also develop seizures and hemiparesis. If treatment is not taken, the patient can go into a coma after a few weeks. In pregnancy, toxoplasmosis can be dangerous to the baby. Diagnosis is by a blood test to detect the antibodies to the parasite in the blood. CT scan and MRI will show multiple lesions in the basal ganglia and the corticomedullary junction. With treatment using pyrimethamine and sulfadiazine, most patients improve within one to two weeks. Treatment has to be taken for six weeks followed by a maintenance dose.
  • Cryptococcal Meningitis. Cryptococcal meningitis is a serious infection, which causes swelling and inflammation of the brain and spinal cord. It is caused by the fungus Cryptococcus neoformans. HIV-positive patients with a CD4 count of 50 or less are more likely to develop this opportunistic infection. Symptoms include headache, vomiting, and fever. Diagnosis is by radiology which reveals focal lesions. CSF testing reveals the organism. Treatment is with antibiotics and even after treatment, relapses occur in immune-suppressed patients. If untreated, this disease can be fatal.
  • Progressive multifocal leukoencephalopathy (PML). PML is a neurological progressive disease, which affects 5% of AIDS patients. It has no specific treatment and the patient dies within six months. However, highly active ART (HAART) sometimes along with steroids may be effective to save the patient if given earlier on. PML is found in 85% of the population but stays inactive in healthy individuals due to the uncompromised immune system. In HIV+ patients with AIDS, the immune system is weakened and therefore PML virus becomes active. PML is caused by the John Cunningham virus (JCV) – named after the first patient in whom it was discovered. This virus destroys the cells that produce myelin – a fatty covering which protects the brain and spinal cord cells. As the name suggests, this disease is progressive. It is multifocal – meaning it is found in multiple parts of the brain. At times, only one localized lesion may be seen. Leucoencephalopathy means this disease affects only the white matter of the brain, though at times the grey matter may also get involved. Symptoms include mental deterioration, loss of vision, speech disturbances, ataxia (inability to coordinate voluntary muscle movements), paralysis, and lastly coma.
  • Aids Dementia Complex (ADC) or HIV encephalopathy. AIDS dementia complex (ADC) also called AIDS dementia or HIV encephalopathy is characterized by impairment of brain function. It is progressive and involves behavioral changes and abnormal motor functions. The progression may be slow or rapid. Symptoms of ADC vary from individual to individual. It adversely affects four functions of the brain namely: mood, thinking capacity, behavior and coordination of movement. This is not an opportunistic infection, but experts believe that the virus indirectly destroys the brain cells. Formerly the incidence was more but now after HAART (highly active antiretroviral therapy) medicines are available and prevalence has decreased. It is seen in only 10% to 15% of AIDS cases and the risk increases after the age of 50 years. Diagnosis of ABC is very difficult and it is arrived at by exclusion of other causes of encephalopathy in AIDS. Radiological studies such as CT scans, MRI, and CSF examination help. A mental status examination is an important part of the clinical assessment of brain damage and can help significantly in diagnosing ABC. Treatment with ART given earlier is the only alternative and this significantly improves prognosis though close monitoring is necessary.
  • AIDS wasting syndrome (Cachexia). Aids-wasting syndrome is characterized by a loss of at least 10 % of your body weight, which is mainly muscle mass. It is difficult to regain this lost muscle mass. Other symptoms include fever, loss of appetite, fatigue, and diarrhea of long-standing duration. AIDS wasting syndrome is seen less now than in the past thanks to HAART (Highly Active Antiretroviral Therapy). This syndrome can be controlled (not reversed) by medicines, which should be accompanied by a good diet rich in calories and proteins to maintain weight and muscle mass. Regular exercise is also advised, especially weight lifting to build muscle. Medicines for diarrhea are given when necessary and appetite-increasing tonics are also given.

Ocular opportunistic diseases and complications

  • Cytomegalovirus(CMV) retinitis. The cytomegalovirus belongs to the herpes family and was a fairly common reason for blindness and death in AIDS patients. In the 1980s and 1990s, the cytomegalovirus affected about one-third of patients who developed AIDS and in whom the CD4 count had fallen below 50/mm³. Today, due to antiretroviral therapy, this incidence has fallen significantly by over 55% to 83%. In the immune-competent host, this virus lies dormant. When reactivated due to the compromised immunity, this virus causes destructive blinding retinitis. In the earlier stages, the disease is asymptomatic (without symptoms). Symptoms when present,  include blurring of vision, partial loss of vision in one eye and flashing lights. Diagnosis. On examination with an ophthalmoscope, the retina appears pale with a perivascular distribution of hemorrhages. These hemorrhages then progress to involve the whole retina and cause blindness. Prompt and aggressive treatment can possibly prevent blindness. Treatment includes systemic and local antiretroviral medicines, which can arrest the progress of this disease. The damage cannot, however, be reversed.

Tumors and Cancers seen In HIV/AIDS

Patients with AIDS are very prone to cancers and the incidence of these cancers has not changed with the antiretroviral therapy except for two:  Kaposi’s sarcoma and non-Hodgkin’s lymphoma. Highly active antiretroviral therapy (HAART) has significantly reduced the incidence of these two cancers.

  •  HIV, AIDS and Kaposi’s sarcoma. Kaposi’s sarcoma (KS) is a growth (tumor) caused by the herpes virus called the Human Herpes Virus 8 (HHV8). Kaposi’s sarcoma once used to be rare but HIV is now the most common cause of KS, which is seen in 15 % of AIDS patients. HIV increases the risk of developing Kaposi’s sarcoma 20,000 times as compared to a person without HIV. Kaposi’s sarcoma usually presents as red, purple or brownish raised lesions over the skin. These lesions may be single, localized or disseminated. They are usually without symptoms, but at times they may be painful when present on the face, legs or the groin. There may be internal involvement when the organs namely the lungs, the gastrointestinal tract and the lungs may get involved. Symptoms. Lung involvement causes a cough, dyspnea, chest pain and hemoptysis (blood in sputum). Gastrointestinal involvement causes abdominal pain, diarrhea, intestinal obstruction and bleeding. Treatment is a combination of anti-HIV medication chemotherapy, radiotherapy, and surgery. Prognosis is good and improves with early treatment with HAART.
  • Non-Hodgkin’s lymphoma. Non-Hodgkin’s lymphoma is a tumor of the lymphatic system, which develops from the lymphocyte cells. It is found in less than 10% of the AIDS patients. It is commonly seen associated with the Central Nervous System (CNS) such as the brain. Prognosis of cerebral tumors is poor and the patient dies within three months if he or she is not on ART. Tumors, which are present outside the CNS are treated with chemotherapy, which makes the patient more vulnerable to opportunistic infections. Symptoms include swollen lymph nodes in the neck or the armpits or the groin, chest pain, abdominal pain, loss of weight and fever. The malignant lymphocytes of Non-Hodgkin’s lymphoma are generally present in the lymph node, but they can also spread to other parts of the lymphatic system, which include the lymphatic vessels, spleen, adenoids, thymus and the bone marrow. Rarely this tumor can also involve organs outside the lymphatic system.