nfections of humans caused by parasites number in the billions and range from relatively innocuous to fatal. The diseases caused by these parasites constitute major human health problems throughout the world.

Washington area health departments are stepping up Lyme disease education and prevention efforts in response to a steep rise in the number of reported cases of the tick-borne illness in Maryland, Virginia and the District.

Global surface temperatures have increased about 0.6°C (plus or minus 0.2°C) since the late-19th century, and about 0.4°F (0.2 to 0.3°C) over the past 25 years (the period with the most credible data). The warming has not been globally uniform. Some areas (including parts of the southeastern U.S.) have, in fact, cooled over the last century.

International travel can pose various risks to health, depending on the characteristics of both the traveller and the travel.Travellers may encounter sudden and significant changes in altitude, humidity, microbes and temperature, which can result in ill-health.

The noise problems of the past are incomparable with those plaguing modern society: the roar of aircraft, the thunder of heavily laden lorries and the thumps and whines of industry provide a noisy background to our lives. But such noise can be not only annoying but also damaging to the health, and is increasing with economic development.

The influence of ecological factors on the activity of drugs is very important. The drug industries pay better prices for drugs of high quality. Many species of medicinal plants grow wild in different parts of the world. The plants are scattered and it becomes difficult to collect and process them.

Allergies are abnormal immune system reactions to things that are typically harmless to most people. When you're allergic to something, your immune system mistakenly believes that this substance is harmful to your body. Allergic reactions are sensitivities to a specific substance, called an allergen , that is contacted through the skin, inhaled into the lungs, swallowed, or injected.

The term "global warming" is a specific case of the more general term "climate change" (which can also refer to "global cooling," such as occurs during ice ages). In principle, "global warming" is neutral as to the period or causes, but in common usage, "global warming" generally refers to recent warming, and implies a human influence.