Infection-associated renal disease (kidney disease; nephropathies)

• What is Kidney Disease and Infection (nephropathies)
• Statistics on Kidney Disease and Infection (nephropathies)
• Risk Factors for Kidney Disease and Infection (nephropathies)
• Progression of Kidney Disease and Infection (nephropathies)
• Symptoms of Kidney Disease and Infection (nephropathies)
• Clinical Examination of Kidney Disease and Infection (nephropathies)
• How is Kidney Disease and Infection (nephropathies) Diagnosed?
• Prognosis of Kidney Disease and Infection (nephropathies)
• How is Kidney Disease and Infection (nephropathies) Treated?

What is Kidney Disease and Infection (nephropathies)

The main area affected by Kidney disease and infection is the glomeruli of the kidney’s.

Statistics on Kidney Disease and Infection (nephropathies)

The incidence of kidney disease varies with the nature of infection.

The common infections with their relative incidence are listed below:

1. Hepatitis B virus (HBV): HBV is prevalent world-wide and has infected more than 2000 million people, with about 300 million carriers. In non-endemic areas, the disease mainly affects males with predisposing factors for the development of HBV such as intravenous drug use. In endemic areas of Asia and Africa, HBV infection is a major cause of glomerular kidney disease, accounting for 80-100% of children and 30-45% of adults with membranous glommerulopathy.

2. Hepatitis C: Incidence varies with demographics, being greatest in patients who require multiple transfusions and in intravenous drug users. It has been suggested that up to 80% of haemophiliacs and up to 90% of intravenous drug users carry this disease. Up to 30% of patients with HCV infection have abnormal findings on urinary investigation.

3. Human Immunodeficiency Virus (HIV): Kidney disease occurs more commonly in African/African Americans, and intravenous drug users who carry the HIV virus. It has also been described with increased frequency in HIV-positive mothers.

4. Infective Bacterial Endocarditis: Kidney disease is a relatively frequent complication of this condition.

5. Suppurative infections.

6. Protozoan/parasitic infection: 50% of patients who develop these infections will develop mild or severe renal disease. The frequency of parasitic and protozoan infections is heavily dependant on geographical location, as this type of infection is endemic throughout the third world.

Risk Factors for Kidney Disease and Infection (nephropathies)

These include those relevant to the development of primary infection.

Little is known about the risk factors associated with subsequent development of kidney disease.

1. HBV/HCV/HIV: Intravenous drug use, unprotected sexual intercourse, multiple sexual partners, multiple blood transfusions. In non-endemic areas, HBV infection mainly affects males with predisposing factors for the development of HBV such as intravenous drug use. HIV causes renal disease more commonly in blacks, and intravenous drug users. HIV has also been described with increased frequency in HIV-positive mothers.

2. Bacterial endocarditis: Intravenous drug use, rheumatic heart disease, congenital heart disease, prosthetic heart valve, source of chronic infection (such as chronic osteomyelitis).

3. Protozoal infection: Poor hygiene, poor food preparation, area of high mosquito activity.

Progression of Kidney Disease and Infection (nephropathies)

The natural history of renal disease depends on the infection involved and the stage to which that infection has progressed. It must be remembered that renal disease is one feature of the disease, which may not be the primary threat to the patient health.

1. HBV: On development of renal disease, patients will present with nephrotic syndrome and small amounts of blood in the urine (microscopic haematuria.) Raised blood pressure and renal failure are rare occurrences.

2. HCV: Again most patients present with nephrotic syndrome and microscopic haematuria, but may also feature red blood cell casts.

3. HIV: Renal disease may be the first clinical manifestion of HIV infection. The patient will develop a severe nephrotic syndrome with rapid deterioration to end stage renal failure over several weeks to months. The condition may occur in patients without full-blown AIDS. There is no proven therapy to slow the progression of this condition.

4. Bacterial Endocarditis: There are a number of mechanisms of renal injury in this condition. The hallmarks of this condition are the development of microscopic haematuria, urinary red blood cell casts, pyuria and moderate proteinuria (nephrotic syndrome only occurs in 25% of those affected by renal disease.)

5. Protozoan/parasitic infection: The natural history of thee conditions depends on the organism involved. Malaria parasites may induce nephrotic syndrome in its renal disease process, that may not resolve upon eradication of the blood borne parasite. In general, however, eradication of the offending parasite leads to the resolution of renal disease.

How is Kidney Disease and Infection (nephropathies) Diagnosed?

Investigations will be undertaken to both establish the cause of infection and assess the severity of renal disease. Blood tests will be required to detect the presence infective organisms including HBV, HCV, HIV and malaria. The kidneys will also be tested through urinary and blood tests to assess the extent of the damage causes by infection.

Prognosis of Kidney Disease and Infection (nephropathies)

1. HBV: Children with HBV renal disease have a good prognosis with almost 2/3 entering spontaneous remission over three years. The prognosis is poor in adults however, with 30% suffering a progressive decline in renal function.

2. HCV: The rate of progression of renal disease is variable, which rarely persists due to the relative incurability of HCV infection.

3. HIV: Prognosis is poor typically deteriorating to end stage renal failure over several weeks to months. The condition may occur in patients without full-blown AIDS. There is no proven therapy to slow the progression of this condition.

4. Bacterial Endocarditis: This condition has a good prognosis as the primary condition is normal short-lived with appropriate antibiotic therapy.

5. Protozoan/parasitic infection: In general, eradication of the offending parasite leads to the resolution of renal disease.

How is Kidney Disease and Infection (nephropathies) Treated?

The treatment of infection associated renal disease should focus on the eradication of primary infection. In some cases, however, such as hepatitis C and HIV infection, this is currently not possible. The patient must be therefore monitored and supported through the complications of renal disease. Appropriate management of nephrotic syndrome and renal failure is required, with the employment of dialysis if the conditions cannot be controlled by more conservative means.

Specific management steps for the common causes of this condition are outline below:

1. HBV/HCV: Interferon-alpha may reduce antigenaemia, stabilise renal disease and slow the progression to renal failure. Relapse, however, is expected on withdrawal of this expensive therapeutic option.

2. HIV: There is no proven therapy for this disease, but recent reials have shown that HAART (High Active Anti-Retrovial Therapy) reduces the occurrence of nephropathy in those who have not development the nephropathy and improves outcome of those who have developed the condition.

3. Infective Bacterial Endocarditis: The renal condition invariably resolves with resolution of primary infection. Treatment requires high dose, extended duration antibiotics.