Lesson 8

Lesson 8

Opportunistic Infections

After completing this lesson, you will be able to:

· list at least ten opportunistic infections associated with HIV infection;

· suggest therapies for such infections; and

· teach your students the topic “Opportunistic Infections”.

As we learned in Lesson 2, HIV attacks the immune system, the body's "security force" that fights off infections. When the immune system breaks down, you lose this protection and can develop many serious, often deadly infections and cancers. These are called "opportunistic infections" (OIs) because they take advantage of the body's weakened defenses. Listed below are the major OIs & cancers that can occur during late-stage HIV disease.

Candidiasis

There are two main types of candidiasis (of the mouth and throat, and of the vagina) and systemic disease (of the oesophagus, and disseminated disease). The mouth and throat variant (oropharyngeal candidiasis or OPC) is believed to occur at least once in the lifetime of all HIV-infected patients. While OPC is not a cause of death, it causes oral pain and makes swallowing difficult. The symptom of oesophageal candidiasis is pain in the chest that increases with swallowing, and causes difficulty in swallowing. Disseminated candidiasis causes fever and symptoms in the organs affected by the disease.

Herpes simplex and Herpes zoster

Herpes simplex virus infection (HSV, which causes sores around the mouth and genitals) and herpes zoster virus infection ('zonal' herpes or shingles) are not life-threatening but can be extremely painful. Both can cause encephalitis, which can be life threatening. Treatment with acyclovir is only marginally effective in herpes zoster but it is sometimes dramatic in HIV-associated herpes simplex with extensive ulceration.

Cryptococcal meningitis

Cryptococcal infection is caused by a fungus which primarily infects the brain. Systemic mycoses such as cryptococcosis probably cause about 5% of all HIV-associated deaths worldwide. Cryptococcosis most often appears as meningitis and occasionally as pulmonary or disseminated disease. Cryptococcal meningitis (CRM) is the most frequent systemic fungal infection in HIV-infected persons. Without treatment, life expectancy is probably less than a month. Cryptococcosis is relatively easy to diagnose.

Tuberculosis

Tuberculosis is a bacterial infection that primarily infects the lungs. Tuberculosis is the leading HIV-associated opportunistic disease in developing countries. For people who are dually infected with HIV and TB, the risk of developing active tuberculosis is 30-50 fold higher than for people infected with TB alone. And because Mycobacterium can spread through the air, the increase in active TB cases among dually infected people means:

more transmission of the TB germ
more TB and carriers
more TB in the whole population.

Tuberculosis is harder to diagnose in HIV-positive people than those who are uninfected. The diagnosis of TB is important because TB progresses faster in HIV-infected people. Also, TB in HIV-positive people is more likely to be fatal if undiagnosed or left untreated. TB occurs earlier in the course of HIV infection than other opportunistic infections.

A proper combination of anti-TB drugs achieves both prevention and cure:

Effective treatment quickly makes the individual non-contagious. This prevents further spread of the TB germ.
The DOTS (directly observed short course) treatment strategy recommended by WHO treats TB in HIV-infected persons as effectively as it treats those without the virus. A complete cure takes 6 to 8 months and uses a combination of antibiotics. In addition to curing the individual, it also prevents further spread of the disease to others. This is why treating infectious cases of TB has important benefits for society as a whole. Isoniazid preventive therapy is recommended as a health-preserving measure for HIV-infected persons at risk of TB. TB prophylaxis has been shown to increase the survival of HIV-infected persons at risk of TB.

Diagnosis and treatment of the following HIV related opportunistic infections require medium infrastructure.

Cryptosporidiosis - isosporiasis

Cryptosporidiosis (crypto) and isosporiasis are both caused by parasite. Crypto is easily spread by contaminated food or water, or direct contact with an infected person or animal. Crypto causes diarrhoea, nausea, vomiting and stomach cramps. In people with healthy immune systems, these symptoms do not last more than about a week. However, if the immune system is damaged crypto can continue for a long time. Diarrhoea can interfere with the absorption of nutrients and this can lead to serious weight loss. To confirm diagnosis, the stool is normally checked for parasites and their eggs. There is no drug treatment that clears up or cures crypto.

Kaposi Sarcoma

HIV -associated Kaposi Sarcoma causes dark blue lesions, which can occur in a variety of locations including the skin, mucous membranes, gastrointestinal tract, lungs or lymph nodes. The lesions usually appear early in the course of HIV infection. Treatment depends on the lesions' symptoms and location.

Leishmaniasis

Leishmaniasis is transmitted by sandflies. The most serious of its four forms is visceral leishmaniasis (VL)- also know as kala azar-, which is characterised by irregular bouts of fever, substantial weight loss, swelling of the spleen and liver and anaemia (occasionaly serious). Recently, there has been an increase in overlapping of VL and HIV infection.

PCP

Pneumocystis carinii pneumonia is caused by a parasite that infects the lungs.

PCP is the most frequent HIV associated opportunistic infection in industrialised countries but appears to be less frequent for example in Africa. The symptoms are mainly pneumonia along with fever and respiratory symptoms such as dry cough, chest pain and dypsnoea. Definitive diagnosis requires microscopy of bodily tissues or fluids.

List of Opportunistic Infections

Bacterial Infections

Mycobacterium Avium Complex (MAC)
Mycobacterium Kansasii
Salmonellosis
Syphilis & Neurosyphilis
Tuberculosis (TB)

Malignancies (Cancers)

Anal Dysplasia/Cancer
Cervical Dysplasia/Cancer
Kaposi's Sarcoma (KS)
Lymphomas

Viral Infections

Cytomegalovirus (CMV)
Hepatitis C
Herpes Simplex Virus (oral & genital herpes)
Herpes Zoster Virus (shingles)
Human Papiloma Virus (HPV, genital warts, anal/cervical dysplasia/cancer)
Molluscum Contagiosum
Oral Hairy Leukoplakia (OHL)

· Progressive Multifocal Leukoencephalopathy (PML)

Fungal Infections

Aspergillosis
Candidiasis (thrush, yeast infection)
Coccidioidomycosis
Cryptococcal Meningitis
Histoplasmosis

Protozoal Infections

Cryptosporidiosis
Isosporiasis
Microsporidiosis
Pneumocystis Carinii Pneumonia (PCP)
Toxoplasmosis

Neurological Conditions

AIDS Dementia Complex (ADC)
Peripheral Neuropathy

Other Conditions and Complications

Apthous Ulcers
Thrombocytopenia
Wasting Syndrome

TREATMENT OF HIV-RELATED OPPORTUNISTIC INFECTIONS

Some of the opportunistic infections are easier to treat than others. Some opportunistic infections and symptoms such as candidiasis of the mouth and throat and vaginal candidiasis ('thrush'), herpes zoster and herpes simplex can be managed effectively through home-based care. In a home-based care setting diagnosis is made by symptoms.

Some opportunistic infections can be treated when there is minimum health infrastructure present. When minimum infrastructure is available, diagnosis can be made by symptoms or use of a simple microscope. Infections that can be diagnosed in minimum infrastructures are oral candidiasis, pulmonary TB, herpes, and cryptococcal meningitis.

In medium infrastructure setting, the facilities available are x-ray equipment or culture facilities. Using these, opportunistic infections as extra-pulmonary TB, cryptosporidiosis-isopsoriasis, PCP and Kaposi Sarcoma can be diagnosed and treated.

Opportunistic infections such as toxoplasmosis, Mycobacterium avium complex disease (MAC) and Cytomegalovirus infection (CMV) can be diagnosed and treated in places with advanced infrastructure. Treating these infections is often impossible in resource poor countries. Many developing countries lack the advanced equipment and infrastructure (such as CT scanning) needed to treat these more complex infections.

Drugs for treatment of HIV-related opportunistic infections

HIV/AIDS care requires a range of essential medicines, in addition to antiretrovirals. If available, these effective and relatively inexpensive drugs can prevent or treat many of the common HIV-related diseases. These are the diseases that are responsible for the main burden of illness and death in high-prevalence countries.

Effective treatment depends on general health services being able to procure, store, select and administer the necessary drugs and to provide related treatment, care and diagnostic services to monitor health status and treatment response. Where health centres and district hospitals are available and accessible, diagnosis of the common infections and complications related to HIV/AIDS (e.g. TB, pneumonia, diarrhoea and candida infection of the mouth and throat) is usually possible, and these conditions can be treated with inexpensive, effective antibiotics and basic nursing procedures.

Prevention of HIV-related opportunistic infections

Several HIV-related infections can be prevented. Following successful treatment, prophylaxis can also prevent disease recurrence (TB, salmonella, cryptococcus). Although the variety of HIV-related illnesses, for example in Africa, differs from that in industrialised countries, several of the most common opportunistic infections are open to prevention through antibiotic prophylaxis.

Resources: Posters showing a listing of opportunistic infections and diagrams of symptoms of some of the infections.
Procedure: Display the poster listing the opportunistic infections in class. Ask students to work in groups to discuss the symptoms of the infections. Assign at least four OIs to each group. At the end of the group work, request a representative of the group to report to the whole class. Evaluate the lesson through a series of questions derived from the posters.

In this lesson, we learned that

HIV attacks the immune system, the body's "security force" that fights off infections. When the immune system breaks down, you lose this protection and can develop many serious, often deadly infections and cancers. These are called "opportunistic infections" (OIs) because they take advantage of the body's weakened defenses.