The principal reservoir of human infection in Britain is probably cattle and sheep in which the infection is usually sub-clinical. The diagnosis is con?rmed by the detection of serum antibodies to Coxiella burneti. The organism is sensitive to tetracycline.
The complication is frequently fatal, being associated with HAEMOGLOBINURIA, JAUNDICE, fever, vomiting and severe ANAEMIA. In an extreme case the patient’s urine appears black. Tender enlarged liver and spleen are usually present. The disease is triggered by quinine usage at subtherapeutic dosage in the presence of P. falciparum infection, especially in the non-immune individual. Now that quinine is rarely used for prevention of this infection (it is reserved for treatment), blackwater fever has become very unusual. Treatment is as for severe complicated P. falciparum infection with renal impairment; dialysis and blood transfusion are usually indicated. When inadequately treated, the mortality rate may be over 40 per cent but, with satisfactory intensive therapy, this should be reduced substantially.... Medical Dictionary
Clinical course The incubation period of enteric fever is 7–21 days. Early symptoms include headache, malaise, dry cough, constipation and a slowly rising fever. Despite the fever, the patient’s pulse rate is often slow and he or she may have an enlarged SPLEEN. In the second week of illness, organisms invade the bloodstream again and symptoms progress. In general, symptoms of typhoid fever are more severe than those of paratyphoid fever: increasing mental slowness and confusion are common, and a more sustained high fever is present. In some individuals, discrete red spots appear on the upper trunk (rose spots). By the third week of illness the patient may become severely toxic, with marked confusion and delirium, abdominal distension, MYOCARDITIS, and occasionally intestinal haemorrage and/or perforation. Such complications may be fatal, although they are unusual if prompt treatment is given. Symptoms improve slowly into the fourth and ?fth weeks, although relapse may occur.
Diagnosis Enteric fever should be considered in any traveller or resident in an ENDEMIC area presenting with a febrile illness. The most common di?erential diagnosis is MALARIA. Diagnosis is usually made by isolation of the organism from cultures of blood in the ?rst two weeks of illness. Later the organisms are found in the stools and urine. Serological tests for ANTIBODIES against Salmonella typhi antigens (see ANTIGEN) (the Widal test) are less useful due to cross-reactions with antigens on other bacteria, and di?culties with interpretation in individuals immunised with typhoid vaccines.
Treatment Where facilities are available, hospital admission is required. Antibiotic therapy with chloramphenicol or amoxyacillin is e?ective. However, the potential toxicity of the former and the widespread resistance that has developed to both these antibiotics has led to the use of QUINOLONES such as CIPROFLOXACIN as the initial therapy for enteric fever in the UK and in areas where resistant organisms are common. A few individuals become chronic carriers of the organisms after they have recovered from the symptoms. These people are a potential source of spread to others and should be excluded from occupations that involve handling food or drinking-water.
Prolonged courses of antibiotic therapy may be required to eradicate carriage.
Prevention Worldwide, the most important preventive measure is improvement of sanitation and maintenance of clean water supplies. Vaccination is available for travellers to endemic areas.... Dictionary of Tropical Medicine
Causes The cause of fever is the release of fever-producing proteins (pyrogens) by phagocytic cells called monocytes and macrophages, in response to a variety of infectious, immunological and neoplastic stimuli. The lymphocytes (see LYMPHOCYTE) play a part in fever production because they recognise the antigen and release substances called lymphokines which promote the production of endogenous pyrogen. The pyrogen then acts on the thermoregulatory centre in the HYPOTHALAMUS and this results in an increase in heat generation and a reduction in heat loss, resulting in a rise in body temperature.
The average temperature of the body in health ranges from 36·9 to 37·5 °C (98·4 to 99·5 °F). It is liable to slight variations from such causes as the ingestion of food, the amount of exercise, the menstrual cycle, and the temperature of the surrounding atmosphere. There are, moreover, certain appreciable daily variations, the lowest temperature being between the hours of 01.00 and 07.00 hours, and the highest between 16.00 and 21.00 hours, with tri?ing ?uctuations during these periods.
The development and maintenance of heat within the body depends upon the metabolic oxidation consequent on the changes continually taking place in the processes of nutrition. In health, this constant tissue disintegration is exactly counterbalanced by the consumption of food, whilst the uniform normal temperature is maintained by the adjustment of the heat developed, and of the processes of exhalation and cooling which take place, especially from the lungs and skin. During a fever this balance breaks down, the tissue waste being greatly in excess of the food supply. The body wastes rapidly, the loss to the system being chie?y in the form of nitrogen compounds (e.g. urea). In the early stage of fever a patient excretes about three times the amount of urea that he or she would excrete on the same diet when in health.
Fever is measured by how high the temperature rises above normal. At 41.1 °C (106 °F) the patient is in a dangerous state of hyperpyrexia (abnormally high temperature). If this persists for very long, the patient usually dies.
The body’s temperature will also rise if exposed for too long to a high ambient temperature. (See HEAT STROKE.)
Symptoms The onset of a fever is usually marked by a RIGOR, or shivering. The skin feels hot and dry, and the raised temperature will often be found to show daily variations – namely, an evening rise and a morning fall.
There is a relative increase in the pulse and breathing rates. The tongue is dry and furred; the thirst is intense, while the appetite is gone; the urine is scanty, of high speci?c gravity and containing a large quantity of solid matter, particularly urea. The patient will have a headache and sometimes nausea, and children may develop convulsions (see FEBRILE CONVULSION).
The fever falls by the occurrence of a CRISIS – that is, a sudden termination of the symptoms – or by a more gradual subsidence of the temperature, technically termed a lysis. If death ensues, this is due to failure of the vital centres in the brain or of the heart, as a result of either the infection or hyperpyrexia.
Treatment Fever is a symptom, and the correct treatment is therefore that of the underlying condition. Occasionally, however, it is also necessary to reduce the temperature by more direct methods: physical cooling by, for example, tepid sponging, and the use of antipyretic drugs such as aspirin or paracetamol.... Medical Dictionary
The mainstays of treatment are ANTIHISTAMINE DRUGS, taken by mouth, and the use of steroid and cromoglycate nasal sprays and eye drops. Occasionally desensitisation by injection may work if the particular allergen is known.... Medical Dictionary
course of the week. (See also LEGIONNAIRE’S DISEASE.)... Medical Dictionary
Louse-borne relapsing fever is an EPIDEMIC disease, usually associated with wars and famines, which has occurred in practically every country in the world. For long confused with TYPHUS FEVER and typhoid fever (see ENTERIC FEVER), it was not until the 1870s that the causal organism was described by Obermeier. It is now known as the Borrelia recurrentis, a motile spiral organism 10–20 micrometres in length. The organism is transmitted from person to person by the louse, Pediculus humanus.
Symptoms The incubation period is up to 12 days (but usually seven). The onset is sudden, with high temperature, generalised aches and pains, and nose-bleeding. In about half of cases, a rash appears at an early stage, beginning in the neck and spreading down over the trunk and arms. JAUNDICE may occur; and both the LIVER and the SPLEEN are enlarged. The temperature subsides after ?ve or six days, to rise again in about a week. There may be up to four such relapses (see the introductory paragraph above).
Treatment Preventive measures are the same as those for typhus. Rest in bed is essential, as are good nursing and a light, nourishing diet. There is usually a quick response to PENICILLIN; the TETRACYCLINES and CHLORAMPHENICOL are also e?ective. Following such treatment the incidence of relapse is about 15 per cent. The mortality rate is low, except in a starved population.
Tick-borne relapsing fever is an ENDEMIC disease which occurs in most tropical and sub-tropical countries. The causative organism is Borrelia duttoni, which is transmitted by a tick, Ornithodorus moubata. David Livingstone suggested that it was a tick-borne disease, but it was not until 1905 that Dutton and Todd produced the de?nitive evidence.
Symptoms The main di?erences from the louse-borne disease are: (a) the incubation period is usually shorter, 3–6 days (but may be as short as two days or as long as 12); (b) the febrile period is usually shorter, and the afebrile periods are more variable in duration, sometimes only lasting for a day or two; (c) relapses are much more numerous.
Treatment Preventive measures are more di?cult to carry out than in the case of the louse-borne infection. Protective clothing should always be worn in ‘tick country’, and old, heavily infected houses should be destroyed. Curative treatment is the same as for the louse-borne infection.... Medical Dictionary
Rheumatic fever is now extremely uncommon in developed countries, but remains common in developing areas. Diagnosis is based on the presence of two or more major manifestations – endocarditis (see under HEART, DISEASES OF), POLYARTHRITIS, chorea, ERYTHEMA marginatum, subcutaneous nodules – or one major and two or more minor ones – fever, arthralgia, previous attacks, raised ESR, raised white blood cell count, and ELECTROCARDIOGRAM (ECG) changes. Evidence of previous infection with streptococcus is also a criterion.
Clinical features Fever is high, with attacks of shivering or rigor. Joint pain and swelling (arthralgia) may a?ect the knee, ankle, wrist or shoulder and may migrate from one joint to another. TACHYCARDIA may indicate cardiac involvement. Subcutaneous nodules may occur, particularly over the back of the wrist or over the elbow or knee. Erythema marginatum is a red rash, looking like the outline of a map, characteristic of the condition.
Cardiac involvement includes PERICARDITIS, ENDOCARDITIS, and MYOCARDITIS. The main long-term complication is damage to the mitral and aortic valves (see HEART).
The chief neurological problem is chorea (St Vitus’s dance) which may develop after the acute symptoms have subsided.
Chronic rheumatic heart disease occurs subsequently in at least half of those who have had rheumatic fever with carditis. The heart valve usually involved is the mitral; less commonly the aortic, tricuspid and pulmonary. The lesions may take 10–20 years to develop in developed countries but sooner elsewhere. The heart valves progressively ?brose and ?brosis may also develop in the myocardium and pericardium. The outcome is either mitral stenosis or mitral regurgitation and the subsequent malfunction of this or other heart valves a?ected is chronic failure in the functioning of the heart. (see HEART, DISEASES OF).
Treatment Eradication of streptococcal infection is essential. Other features are treated symptomatically. PARACETAMOL may be preferred to ASPIRIN as an antipyretic in young children. One of the NON-STEROIDAL ANTIINFLAMMATORY DRUGS (NSAIDS) may bene?t the joint symptoms. CORTICOSTEROIDS may be indicated for more serious complications.
Patients who have developed cardiac-valve abnormalities require antibiotic prophylaxis during dental treatment and other procedures where bacteria may enter the bloodstream. Secondary cardiac problems may occur several decades later and require replacement of a?ected heart valves.... Medical Dictionary
Symptoms There are headache, feverishness, general sensations like those of INFLUENZA, flushed face and bloodshot eyes, but no signs of CATARRH. The fever passes off in three days, but the patient may take some time to convalesce.
Treatment As there is no specific remedy, PROPHYLAXIS is important. This consists of the spraying of rooms with an insecticide such as GAMMEXANE; the application of insect repellents such as dimethyl phthalate to the exposed parts of the body (e.g. ankles, wrists and face), particularly at sunset; and the use of sandfly nets at night. Once the infection is acquired, treatment consists of rest in bed, light diet and aspirin and codeine.... Medical Dictionary
Symptoms The period of incubation (i.e. the time elapsing between the reception of infection and the development of symptoms) varies somewhat. In most cases it lasts only two to three days, but in occasional cases the patient may take a week to develop his or her ?rst symptoms. The occurrence of fever is usually short and sharp, with rapid rise of temperature to 40 °C (104 °F), shivering, vomiting, headache, sore throat and marked increase in the rate of the pulse. In young children, CONVULSIONS or DELIRIUM may precede the fever. The rash usually appears within 24 hours of the onset of fever and lasts about a week.
Complications The most common and serious of these is glomerulonephritis (see under KIDNEYS, DISEASES OF), which may arise during any period in the course of the fever, but particularly when DESQUAMATION occurs. Occasionally the patient develops chronic glomerulonephritis. Another complication is infection of the middle ear (otitis media – see under EAR, DISEASES OF). Other disorders a?ecting the heart and lungs occasionally arise in connection with scarlet fever, the chief of these being ENDOCARDITIS, which may lay the foundation of valvular disease of the heart later in life. ARTHRITIS may produce swelling and pain in the smaller rather than in the larger joints; this complication usually occurs in the second week of illness. Scarlet fever, which is now a mild disease in most patients, should be treated with PENICILLIN.... Medical Dictionary
Louse typhus, in which the infecting rickettsia is transmitted by the louse, is of worldwide distribution. More human deaths have been attributed to the louse via typhus, louse-borne RELAPSING FEVER and trench fever, than to any other insect with the exception of the MALARIA mosquito. Louse typhus includes epidemic typhus, Brill’s disease – which is a recrudescent form of epidemic typhus – and TRENCH FEVER.
Epidemic typhus fever, also known as exanthematic typhus, classical typhus, and louse-borne typhus, is an acute infection of abrupt onset which, in the absence of treatment, persists for 14 days. It is of worldwide distribution, but is largely con?ned today to parts of Africa. The causative organism is the Rickettsia prowazeki, so-called after Ricketts and Prowazek, two brilliant investigators of typhus, both of whom died of the disease. It is transmitted by the human louse, Pediculus humanus. The rickettsiae can survive in the dried faeces of lice for 60 days, and these infected faeces are probably the main source of human infection.
Symptoms The incubation period is usually 10–14 days. The onset is preceded by headache, pain in the back and limbs and rigors. On the third day the temperature rises, the headache worsens, and the patient is drowsy or delirious. Subsequently a characteristic rash appears on the abdomen and inner aspect of the arms, to spread over the chest, back and trunk. Death may occur from SEPTICAEMIA, heart or kidney failure, or PNEUMONIA about the 14th day. In those who recover, the temperature falls by CRISIS at about this time. The death rate is variable, ranging from nearly 100 per cent in epidemics among debilitated refugees to about 10 per cent.
Murine typhus fever, also known as ?ea typhus, is worldwide in its distribution and is found wherever individuals are crowded together in insanitary, rat-infested areas (hence the old names of jail-fever and ship typhus). The causative organism, Rickettsia mooseri, which is closely related to R. prowazeki, is transmitted to humans by the rat-?ea, Xenopsyalla cheopis. The rat is the main reservoir of infection; once humans are infected, the human louse may act as a transmitter of the rickettsia from person to person. This explains how the disease may become epidemic under insanitary, crowded conditions. As a rule, however, the disease is only acquired when humans come into close contact with infected rats.
Symptoms These are similar to those of louse-borne typhus, but the disease is usually milder, and the mortality rate is very low (about 1·5 per cent).
Tick typhus, in which the infecting rickettsia is transmitted by ticks, occurs in various parts of the world. The three best-known conditions in this group are ROCKY MOUNTAIN SPOTTED FEVER, ?èvre boutonneuse and tick-bite fever.
Mite typhus, in which the infecting rickettsia is transmitted by mites, includes scrub typhus, or tsutsugamushi disease, and rickettsialpox.
Rickettsialpox is a mild disease caused by Rickettsia akari, which is transmitted to humans from infected mice by the common mouse mite, Allodermanyssus sanguineus. It occurs in the United States, West and South Africa and the former Soviet Union.
Treatment The general principles of treatment are the same in all forms of typhus. PROPHYLAXIS consists of either avoidance or destruction of the vector. In the case of louse typhus and ?ea typhus, the outlook has been revolutionised by the introduction of e?cient insecticides such as DICHLORODIPHENYL TRICHLOROETHANE (DDT) and GAMMEXANE.
The value of the former was well shown by its use after World War II: this resulted in almost complete freedom from the epidemics of typhus which ravaged Eastern Europe after World War I, being responsible for 30 million cases with a mortality of 10 per cent. Now only 10,000–20,000 cases occur a year, with around a few hundred deaths. E?cient rat control is another measure which reduces the risk of typhus very considerably. In areas such as Malaysia, where the mites are infected from a wide variety of rodents scattered over large areas, the wearing of protective clothing is the most practical method of prophylaxis. CURATIVE TREATMENT was revolutionised by the introduction of CHLORAMPHENICOL and the TETRACYCLINES. These antibiotics altered the prognosis in typhus fever very considerably.... Medical Dictionary
Clinically, yellow fever is characterised by jaundice, fever, chills, headache, gastrointestinal haemorrhage(s), and ALBUMINURIA. The incubation period is 3–6 (up to 10) days. Differentiation from viral hepatitides, other viral haemorrhagic fevers, severe Plasmodium falciparum malaria, and several other infections is often impossible without sophisticated investigative techniques. Infection carries a high mortality rate. Liver histology (biopsy is contraindicated due to the haemorrhagic diathesis) shows characteristic changes; a fulminating hepatic infection is often present. Acute in?ammation of the kidneys and an in?amed, congested gastric mucosa, often accompanied by haemorrhage, are also demonstrable; myocardial involvement often occurs. Diagnosis is primarily based on virological techniques; serological tests are also of value. Yellow fever should be suspected in any travellers from an endemic area.
Management consists of instituting techniques for acute hepatocellular (liver-cell) failure. The a?ected individual should be kept in an isolation unit, away from mosquitoes which could transmit the disease to a healthy individual. Formerly, laboratory infections were occasionally acquired from infected blood samples. Prophylactically, a satisfactory attenuated VACCINE (17D) has been available for around 60 years; this is given subcutaneously and provides an individual with excellent protection for ten years; international certi?cates are valid for this length of time. Every traveller to an endemic area should be immunised; this is mandatory for entry to countries where the infection is endemic.... Dictionary of Tropical Medicine
Haemophilus vaccine (HiB) This vaccine was introduced in the UK in 1994 to deal with the annual incidence of about 1,500 cases and 100 deaths from haemophilus MENINGITIS, SEPTICAEMIA and EPIGLOTTITIS, mostly in pre-school children. It has been remarkably successful when given as part of the primary vaccination programme at two, three and four months of age – reducing the incidence by over 95 per cent. A few cases still occur, either due to other subgroups of the organism for which the vaccine is not designed, or because of inadequate response by the child, possibly related to interference from the newer forms of pertussis vaccine (see above) given at the same time.
Meningococcal C vaccine Used in the UK from 1998, this has dramatically reduced the incidence of meningitis and septicaemia due to this organism. Used as part of the primary programme in early infancy, it does not protect against other types of meningococci.
Varicella vaccine This vaccine, used to protect against varicella (CHICKENPOX) is used in a number of countries including the United States and Japan. It has not been introduced into the UK, largely because of concerns that use in infancy would result in an upsurge in cases in adult life, when the disease may be more severe.
Pneumococcal vaccine The pneumococcus is responsible for severe and sometimes fatal childhood diseases including meningitis and septicaemia, as well as PNEUMONIA and other respiratory infections. Vaccines are available but do not protect against all strains and are reserved for special situations – such as for patients without a SPLEEN or those who are immunode?cient.... Medical Dictionary