A state of the body where the immune system defences do not work properly. This can be the result of illness or the administration of certain drugs (commonly ones used to fight cancer).
The symptoms depend upon the site of the infection. General symptoms such as fever, weight loss and night sweats are common. In the most common form of pulmonary tuberculosis, cough and blood-stained sputum (haemoptysis) are common symptoms.
The route of infection is most often by inhalation, although it can be by ingestion of products such as infected milk. The results of contact depend upon the extent of the exposure and the susceptibility of the individual. Around 30 per cent of those closely exposed to the organism will be infected, but most will contain the infection with no signi?cant clinical illness and only a minority will go on to develop clinical disease. Around 5 per cent of those infected will develop post-primary disease over the next two or three years. The rest are at risk of reactivation of the disease later, particularly if their resistance is reduced by associated disease, poor nutrition or immunosuppression. In developed countries around 5 per cent of those infected will reactivate their healed tuberculosis into a clinical problem.
Immunosuppressed patients such as those infected with HIV are at much greater risk of developing clinical tuberculosis on primary contact or from reactivation. This is a particular problem in many developing countries, where there is a high incidence of both HIV and tuberculosis.
Diagnosis This depends upon identi?cation of mycobacteria on direct staining of sputum or other secretions or tissue, and upon culture of the organism. Culture takes 4–6 weeks but is necessary for di?erentiation from other non-tuberculous mycobacteria and for drug-sensitivity testing. Newer techniques involving DNA ampli?cation by polymerase chain reaction (PCR) can detect small numbers of organisms and help with earlier diagnosis.
Treatment This can be preventative or curative. Important elements of prevention are adequate nutrition and social conditions, BCG vaccination (see IMMUNISATION), an adequate public-health programme for contact tracing, and chemoprophylaxis. Radiological screening with mass miniature radiography is no longer used.
Vaccination with an attenuated organism (BCG – Bacillus Calmette Guerin) is used in the United Kingdom and some other countries at 12–13 years, or earlier in high-risk groups. Some studies show 80 per cent protection against tuberculosis for ten years after vaccination.
Cases of open tuberculosis need to be identi?ed; their close contacts should be reviewed for evidence of disease. Adequate antibiotic chemotherapy removes the infective risk after around two weeks of treatment. Chemoprophylaxis – the use of antituberculous therapy in those without clinical disease – may be used in contacts who develop a strong reaction on tuberculin skin testing or those at high risk because of associated disease.
The major principles of antibiotic chemotherapy for tuberculosis are that a combination of drugs needs to be used, and that treatment needs to be continued for a prolonged period – usually six months. Use of single agents or interrupted courses leads to the development of drug resistance. Serious outbreaks of multiply resistant Mycobacterium tuberculosis have been seen mainly in AIDS units, where patients have greater susceptibility to the disease, but also in developing countries where maintenance of appropriate antibacterial therapy for six months or more can be di?cult.
Streptomycin was the ?rst useful agent identi?ed in 1944. The four drugs used most often now are RIFAMPICIN, ISONIAZID, PYRAZINAMIDE and ETHAMBUTOL. Three to four agents are used for the ?rst two months; then, when sensitivities are known and clinical response observed, two drugs, most often rifampicin and isoniazid, are continued for the rest of the course. Treatment is taken daily, although thrice-weekly, directly observed therapy is used when there is doubt about the patient’s compliance. All the antituberculous agents have a range of adverse effects that need to be monitored during treatment. Provided that the treatment is prescribed and taken appropriately, response to treatment is very good with cure of disease and very low relapse rates.... nature of the disease tuberculosis has
Pentamidine is also used to treat the tropical disease leishmaniasis.
Side effects may include nausea and vomiting, dizziness, flushing, rash, and taste disturbances.... pentamidine
Whilst an infected patient is frequently asymptomatic, heavy infection can cause jejunal mucosal abnormalities, and an absorptive defect, with weight loss. During the migratory phase an itchy linear rash (larva currens) may be present on the lower abdomen, buttocks, and groins; this gives rise to recurrent transient itching. In an immunosuppressed individual, the ‘hyperinfection syndrome’ may ensue; migratory larvae invade all organs and tissues, including the lungs and brain. Associated with this widespread infection, the patient may develop an Enterobacteriacae spp. SEPTICAEMIA; this, together with S. stercoralis larvae, produces a MENINGOENCEPHALITIS. There is no evidence that this syndrome is more common in patients with HIV infection.
Diagnosis consists of visualisation of S. stercoralis (larvae or adults) in a jejunal biopsy-section or aspirate. Larvae may also be demonstrable in a faecal sample, especially following culture. Eosinophilia may be present in peripheral blood, during the invasive stage of infection. Chemotherapy consists of albendazole. The formerly used benzimidazole compound, thiabendazole, is now rarely prescribed in an uncomplicated infection due to unpleasant side-effects; even so, in the ‘hyperinfection syndrome’ it probably remains the more e?ective of the two compounds.... strongyloidiasis
Infections of the oesophagus are rare but may occur in immunosuppressed patients. The most common are herpes simplex and candidiasis (thrush). Oesophagitis is usually due to reflux of stomach contents, causing heartburn. Corrosive oesophagitis can occur as a result of swallowing caustic chemicals. Both may cause an oesophageal stricture.
Congenital defects include oesophageal atresia, which requires surgery soon after birth. Tumours of the oesophagus are quite common; about 90 per cent are cancerous (see oesophagus, cancer of). Injury to the oesophagus is most commonly caused by a tear or rupture due to severe vomiting and retching. (See also swallowing difficulty.)... oesophagus, disorders of
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