A model for nematodiasis in New Zealand lambs.

A strategic model is described for the epidemiology of mixed nematode infections in New Zealand lambs. The model successfully reproduces known patterns of parasite epidemiology and production loss in lambs under currently implemented control strategies. The variation in model output during sensitivity analysis was within acceptable limits defined by field data. Model output was most sensitive to variation in parameters affecting survival and migration of the free-living stages and host resistance to infection, suggesting that these factors are most influential in regulating parasite populations. It is intended to use the model to focus research on key aspects of nematode epidemiology and control and, following the incorporation of appropriate genetic mechanisms, anthelmintic resistance.     

New drugs in hypertension.

Clonidine, propranolol, bethanidine and debrisoquine effectively decrease blood pressure by suppressing renin secretion or interfering with function of the sympathetic nervous system. In man these compounds exert an antihypertensive effect within several hours or days and their duration of action is sufficient to permit administration twice or thrice daily. Clonidine and propranolol are especially useful if sexual dysfunction or postural hypotension is undesirable. Although bethanidine and debrisoquine may produce these adverse effects, they are beneficial in severe hypertension and produce fewer side effects than guanethidine. Clonidine frequently causes sedation, and rebound hypertension may occur with sudden cessation of therapy. Injudicious use of propranolol may provoke heart failure or asthma in susceptible individuals. The combination of a thiazide diuretic with propranolol and one of hydralazine, bethanidine and debrisoquine may be used to treat severe or complicated hypertension.     

Trends in sales of drugs for asthma in New Zealand,Australia, and the United Kingdom, 1975-81.

As part of an investigation into the recent epidemic of deaths from asthma in New Zealand, trends in the sales of drugs for asthma in New Zealand, Australia, and the United Kingdom during 1975-81 were examined. Data on sales of drugs were obtained from an international pharmaceutical market research organisation. A striking increase in sales of sympathomimetic aerosols, steroid aerosols, and theophylline per caput occurred in all three countries, with the greatest increase occurring in New Zealand. Sales of sodium cromoglycate also increased in New Zealand and the UK but fell in Australia. By 1981 New Zealand had the highest sales of all these drugs per caput. Explanations for the rising mortality from asthma in New Zealand despite large increases in drug sales need to be explored. Although the temporal association between mortality and sales of drugs suggests that direct drug toxicity is unlikely, there may be more subtle adverse effects of drug use.