Microsporidiosis Medical Assignment Help

This is a frequent cause of diarrhoea. Spores can be detected with great accuracy in the stools using a trichrome or a fluorescent stain that attaches to the chitin of the spore surface. Albendazole is effective in eradicating the organism.

FUNGI

Cryptococcus

In the context of HIV with AIDS the commonest presentation is with meningitis, although it can cause pulmonary and disseminated infection. Clinical features of cryptococcal meningitis include headache, fever, impaired conscious level and abnormal affect. Neck stiffness and photophobia are rarely seen. The diagnosis is made on examination of the CSF (a CT scan must be performed first to exclude space-occupying lesions). India ink staining may show the organisms directly and cryptococcal antigen is positive at variabletitre. Cryptococci may be cultured from the CSF  and/or blood.
Signs associated with a poor prognosis include high organism count in the CSF, low white cell count in the CSF, and impaired conscious level at presentation. Treatment is with intravenous amphotericin B or fluconazole. Infection is not eradicated and lifelong maintenance therapy (usually with fluconazole) is needed to suppress infection.

Candida

Mucosal infection with C. albicans is extremely frequent in HIV-infected patients. Oropharyngeal involvement is common and oesophageal Candida causes dysphagia. HIV-infected women may have severe recurrent vulvovaginal Candida infection. Disseminated Candida is relatively uncommon in the context of HIV infection. Treatment is usually with systemic antifungal agents such as fluconazole and ketoconazole.

VIRUSES

Cytomegalovirus (CMV)

CMV is the cause of considerable morbidity in HIVinfected individuals, especially in the later stages of disease. The major problems encountered are retinitis, colitis, oesophagitis, encephalitis and pneumonitis. Polyradiculitis and adrenalitis may also be caused by CMV. The first two are the most common.
CMV RETINITIS. This occurs in up to 30% of AIDS cases and is the commonest cause of eye disease and blindness. Although usually unilateral to begin with the infection frequently progresses to involve both eyes. Presenting features depend on the area of the retina involved (loss of vision being most common with macular involvement) and include:
• Floaters
• Loss of visual acuity and scotoma
• Orbital pain and headache
Examination reveals haemorrhages and exudate which follow the vasculature of the retina (so-called pizza pie appearances). The features are highly characteristic and the diagnosis is made clinically. If untreated, retinitis spreads within the eye destroying the retina within its path. Routine fundoscopy should be carried out regularly on all HIV-infected patients to look for evidence of early infection. Treatment should be started as soon as possible with either ganciclovir or foscarnet. These agents halt disease but do not eradicate it. Reactivation occurs in a majority of cases and may lead to blindness in one or both eyes. Patients thus need long-term maintenance therapy but as these two agents are available only as intravenous preparations insertion of an indwelling line is necessary for long-term self-administered therapy.
CMV COLITIS. This is a cause of abdominal symptoms in AIDS. The usual presenting features include:
• Abdominal pain, often left iliac
• Diarrhoea which may be bloody
• Tenderness
• Low grade fever
Toxic dilatation of the colon may occur in severe cases. Sigmoidoscopy and biopsy may be performed safely if there is no evidence of toxic dilatation on the abdominal radiograph. Histology shows characteristic ‘owl’s eye’ cytoplasmic inclusion bodies. Treatment with ganciclovir or foscarnet is effective.
CMV may affect any site along the gastrointestinal tract giving rise to:
• Oesophageal ulcers, usually solitary in the lower third
• Small bowel ulceration
• An association with sclerosing cholangitis
• Hepatitis

Herpes

HSV types 1 and 2 cause frequent, severe, recurrent infections in people with HIV. There may be extensive ulceration and viral shedding may be prolonged in comparison to immunocompetent individuals. Genital, oral and occasionally disseminated infection are seen. Therapy with acyclovir is effective but frequent recurrences may need suppressive therapy. Acyclovir-resistant HSV (usually due to thymidine kinase-deficient mutations) in HIV-infected patients has become more common. Such strains may respond to foscarnet.

Papovavirus

Progressive multifocal leukencephalopathy (PML) is a demyelinating disease of cerebral white matter caused by papovavirus. The features are of progressive neurological and/or intellectual impairment. MRI scanning is the most sensitive and reveals characteristic multiple white matter lesions. Definitive diagnosis is made on histological and viral examination of brain tissue. There is no specifictreatment for the condition.

BACTERIAL INFECTIONS

Encapsulated bacteria such as Strep. pneumoniae, H. influenzae and Moraxella catarrhalis show an increased incidence in HIV infection and may result in pneumonia or disseminated disease. Recurrent episodes are common.The response to standard antibiotic therapy is usually  good, but long-term prophylaxis may be required if recurrent infection is frequent.

Non-typhoidal Salmonella spp. are frequent pathogens in HIV infection as intact cell-mediated immunity is a crucial part of host defence. Organisms are usually acquired orally and frequently result in disseminated infection. Gastrointestinal disturbance may be minimal, and once in the bloodstream any organ may be infected.
Response to standard antibiotic therapy, depending on laboratory sensitivities, is usually good in the acute phase but recurrent infection is common and long-term suppressive therapy may be necessary.

HN and AIDS 

Iiorating systemic symptoms but on the whole therapy is disappointing. Primary prophylaxis with rifabutin in profoundly immunosuppressed patients (CD counts < 100 mm “) may reduce the incidence of frank MAl infection.

TUMOURS

Kaposi’s sarcoma (KS)

This multifocal disease is caused by a proliferation of vascular endothelial cells, which form slit-like spaces similar to blood essels that trap red blood cells and cause the characteristic purple hue of the tumour. KS commonly involves:
• Skin
• Lymphatics and lymph nodes
• Lung
• Gut
Treatment depends on the site and extent of the lesions. Localized or cutaneous disease may respond to radiotherapy. Disseminated or visceral KS generally requires systemic chemotherapy. KS is particularly common in homosexual men and is rare in those who have acquired HIV via blood products or intravenous drug use. The possible existence of a sexually transmitted cofactor in the aetiology of the condition is being explored.

Lymphoma

Non-Hodgkin’s lymphoma (NHL) of B-cell origin occurs particularly in immunosuppressed individuals. In late stages of AIDS primary CNS NHL is common and responds poorly to therapy. However primary NHL outside the CNS (e.g. gastrointestinal tract or lung) may occur at earlier stages of immunosuppression and is more responsive to therapy.

Mycobacterial infections

An association between HIV infection and M. tuberculosis was recognized early in the epidemic. TB can cause disease when there is only minimal immunosuppression and thus often appears early in the course of HIV infection. In many countries where HIV is spreading and tuberculosis is endemic there is a substantial increase in the incidence of tuberculosis. Cases of HIV-related tuberculosis frequently represent reactivation of latent TB. There is also evidence for newly acquired infection and nosocomial spread in HIV-infected populations. The pattern of disease differs from that in the immunocompetent host in that extra pulmonary and disseminated infection is more common. The response to tuberculin testing is blunted in HIV -positive individuals and is unreliable. Sputum examination may be negative even in pulmonary infection and culture techniques are the best diagnostic tool.
TB usually responds well to standard treatment regimens, although there are increasing numbers of cases of multidrug resistance occurring in HIV-infected individuals, particularly in the USA. Increasing numbers of drugs are used in combination. Treatment is not curative and lifelong maintenance, usually with isoniazid, is required. HIV-infected individuals have shown a high frequency of severe adverse reactions to thioacetazone and this drug, although widely used for tuberculosis in developing countries, should be avoided in this group of patients if possible.
Atypical mycobacteria, particularly M. avium intracellulare complex (MAr) generally appear only in the later ages of AIDS when patients are profoundly immunosuppressed. It is a saprophytic organism of low pathogen- . ity that is ubiquitous in soil and water. Entry may be via the gastrointestinal tract or lungs with dissemination ill infected macrophages.
The major features are of fevers, weight loss and anoreria, Dissemination to the bone marrow causes anaemia. ointestinal symptoms may be prominent with diarand malabsorption. At this stage of disease patients . have other concurrent infections and differentiating AI on clinical grounds is difficult. Direct examination culture of bone marrow, liver, blood or lymph node the diagnosis most reliably.
Mai is  typically resistant to standard antituberculous pies. Newer drugs such as rifabutin in combination c1arithromycin and clofazirnine have shown some mise in reducing the burden of organisms and ameIiorating systemic symptoms but on the whole therapy is disappointing. Primary prophylaxis with rifabutin in profoundly immunosuppressed patients (CD counts < 100 mm “) may reduce the incidence of frank MAl infection.

TUMOURS

Kaposi’s sarcoma (KS)

This multifocal disease is caused by a proliferation of vascular endothelial cells, which form slit-like spaces similar to blood vessels that trap red blood cells and cause the characteristic purple hue of the tumour. KS commonly involves:
• Skin
• Lymphatics and lymph nodes
• Lung
• Gut
Treatment depends on the site and extent of the lesions. Localized or cutaneous disease may respond to radiotherapy. Disseminated or visceral KS generally requires systemic chemotherapy.
KS is particularly common in homosexual men and is rare in those who have acquired HIV via blood products or intravenous drug use. The possible existence of a sexually transmitted cofactor in the aetiology of the condition is being explored.

Lymphoma

Non-Hodgkin’s lymphoma (NHL) of B-cell origin occurs particularly in immunosuppressed individuals. In late stages of AIDS primary CNS NHL is common and responds poorly to therapy. However primary NHL outside the CNS (e.g. gastrointestinal tract or lung) may occur at earlier stages of immunosuppression and is more responsive to therapy.

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