Control of parasitic bronchitis in calves: vaccination or treatment?

A 16-day infection of Dictyocaulus viviparus in two groups of calves was treated with levamisole and fenbendazole respectively. Five days afterwards the calves were reinfected with 4000 larvae and necropsied 21 days later. Although the lungworm burdens of the two groups of calves were reduced by about 70 per cent compared to a control group the clinical signs of dyspnoea, tachypnoea and coughing were indistinguishable from a primary infection. This was due to pulmonary emphysema, oedema and an acute epithelialising pneumonia apparently associated with the death and disintegration of lungworms in situ, the result of an incompletely developed immune response. The results are compared with those obtained with the lungworm vaccine. It was concluded that the outcome of any system of "control" which depends on drug therapy and reinfection is unpredictable and that vaccination offers the only effective method of prophylaxis.

Chronic bronchitis

Our understanding of chronic bronchitis has been hampered by the fact that the diagnosis is based upon historical evidence of recurrent cough and sputum without any requirement that certain physiologic or microscopic criteria be met. Despite the fact that epidemiological studies have implicated viruses, bacteria, and Mycoplasma pneumoniae in a varying percentage of exacerbations, in an individual case it is often difficult to establish a causal role for any agent. Antibiotics seem to reduce the morbidity of an infective exacerbation, but the widespread use of prophylactic antibiotics cannot be justified on the basis of the studies currently available. It would seem that the most sensible approach in the treatment of patients with chronic bronchitis would be to treat them on an individual basis, avoiding the indiscriminate use of antibiotics, but employing them on a trial basis in patients with a demonstrated proclivity for seasonal exacerbations. It is hoped that future clinical trials incorporating only patients meeting the classic criteria for chronic bronchitis and its exacerbations will develop treatments for this significant disease which are more successful than those currently available.

The effect of indomethacin on the response of bronchial epithelium to tobacco smoke

The effect of the anti-inflammatory agent indomethacin on the response of bronchial epithelium to irritation by tobacco smoke has been studied using the specific pathogen free rat as an experimental animal model of bronchitis. Rats given tobacco smoke alone for 2 weeks (25 digaretts during a 4-hr period on each day) showed a marked increase in their epithelial mucous (i. e. goblet) cell numbers in the trachea and at each of the four airway levels of the lung studied. Indomethacin was given by intra-peritoneal injection alone or concurrently with the tobacco smoke at a dose of 2 or 4 mg/kg/bw. When compared with their respective controls, those animals given indomethacin together with the tobacco smoke had significantly fewer mucous cells in their intrapulmonary airway (i.e. inhibition of mucous cell hyperplasia) but there was little inhibitory effect in the trachea. The inhibition of mucous cell hyperplasia afforded by indomethacin was greatest in those animals given the highest dose: the percentage inhibition ranged from 18 per cent to 100 per cent and the greatest effect was seen in the most distal intrapulmonary airways studied. The mechanism of action of Indomethacin and the role of prostaglandin is discussed.

Bovine dictyocaulosis. Pattern of infection and the prevention of parasitic bronchitis

A combined epidemiology and control investigation was performed with parasite-free calves turned out in May on a permanent pasture naturally contaminated with lungworm larvae the previous year. Before the start the field was divided into two plots. One plot was grazed by 12 calves after the first week of May. The other plot was grazed by 12 calves turned out two weeks later. Both groups as well as the plots grazed by them were subdivided six weeks after turning out. Based on a predicted rise in the pasture larval contamination with infective lungworm larvae, one subgroup of each main group was given a tactical anthelmintic treatment six weeks and again eight weeks after their date of turning out. Patent infections from overwintered larvae were detected in both main groups after four weeks of grazing, but not in all individuals of the late turned-out group. The excreted larvae gave rise to pathogenic pasture larval contaminations on the two initial plots five to six weeks after turning out. In the control groups, early turning-out resulted in approx. 10 times higher larval recoveries in faeces and pasture compared to late turning-out. Seven to eight weeks after turning-out critical, severe parasitic bronchitis had developed in the early turned-out control group. In the late turned-out controls, clinical signs were obvious but not critical. Outbreaks were not observed in any of the experimental subgroups, and no larval excretion was observed among them within four to five weeks following treatments. Similarly, no larvae were recovered from their pastures two weeks after treatment and onwards. A third treatment was given to both experimental groups on the same date (August 21) to suppress gastrointestinal parasitism. However, the level of this infection, appeared moderate, probably due to comparatively low precipitation and extensive supplementary feeding given in late summer to compensate for scarcity of grass.

[Investigation concerning some organizational aspects of the care of chronic bronchitis patients]

The epidemiologic importance of chronic bronchitis is stressed, which justifies the preoccupation of the authors for finding the means of detection and diagnosis in view of the application of adequate therapeutical measures. An inquiry was used, taking the form of questionnaire concerning the various medical and social organizatory problems raised by chronic bronchitis. The questionnaire was sent for completion by the various sanitary directions in the districts. The answers were statistically processed and the results justify the necessity for a standardization of methods used in the detection and the diagnosis of patients with chronic bronchitis, as well as for other measures concerning these subjects.

[Field experience of infectious bronchitis vaccination in broiler chickens (author's transl)]

In flocks of broiler chickens showing a high incidence of I.B. infection, double vaccination against I.B. with the H120 strain on the first and 18th-20th day of life, will prevent the disease, and the results of fattening will be improved.

A clinical comparison of ampicillin, ampicillin esters (bacampicillin and pivampicillin) and amoxycillin in acute exacerbations of chronic bronchitis

The results of antibiotic therapy in 271 patients suffering from acute exacerbations of chronic bronchitis are presented. The effectiveness of the better absorbed ampicillin esters (pivampicillin and bacampicillin) is confirmed, but side-effects from the pivampicillin present problems whereas bacampicillin is excellently tolerated, even in twice daily doses of 1600 mg. Amoxycillin, if given in 750 mg doses three times daily by mouth, is also safe and effective against Haemophilus influenzae. However, if accurate MIC results are not available for both ampicillin and amoxycillin, the lesser degree of sensitivity to amoxycillin suggests that use of an ampicillin ester (such as bacampicillin) is to be preferred. Prophylactic use of antibiotics in chronic bronchitis patients does not seem logical to us.

Antibacterial prophylaxis--a clinician's view

The principles of antibacterial prophylaxis and its advantages and disadvantages are reviewed. Controlled trials have shown chemoprophylaxis to be beneficial notably in preventing recurrences of rheumatic carditis and urinary infections and in controlling sepsis after cardiac and hip joint surgery and mid thigh amputations. The recently introduced metronidazole prophylaxis for gastrointestinal and gynaecological operations appears highly effective. The use of prophylaxis is briefly discussed in other situations where its value is less certain or where, in the author's opinion, it is contraindicated.

[Chronic diseases of the respiratory tract (proceedings)]

On account of their increasing social-medical importance chronic diseases of the respiratory tract demand systematic measures for prevention and combat. The size of the problem is described on the basis of the results of epidemiologic investigations. Issuing from the risk degrees of the cardio-respiratory insufficiency (obstruction, hypoxaemia, pulmonary hypertension) care groups are proposed. The combat against tobacco smoking (primary prevention) and long-term treatment of the chronic obstructive bronchitis (tertiary prevention) stand in the foreground of the measures. The solution of this task demands a close cooperation with the basic medical care.

Prevention--everybody's responsibility

The importance of individual responsibility in many aspects of preventive medicine is emphasised in the introduction. A section on infectious disease as applied to Western society today follows with special mention of particular conditions such as turberculosis, influenza, rubella, gastro-intestinal diseases and Legionaire's Disease. The section on non-communicable disease is subdivided into coronary heart disease, malignant neoplasms and chronic bronchitis. It includes some discussion of screening. Short sections on prevention in the elderly, pregnancy and early life, dental health, accidents, alcoholism and drug misuse follow. In the conclusions the difficulty of determining priorities for different societies and the importance of establishing cost effectiveness of preventive measures are covered. The relative importance of societal, governmental and individual preventive measures are described and the authors emphasise that any expensive screening programme must adhere to established criteria.