In yellow fever we have at first a high blood pressure. The pulse rate, which at first corresponds with the rise of temperature, soon shows Faget’s law—a falling pulse with a constant temperature or a constant pulse with a rising temperature. It is a markedly slow pulse after the third day. The blood pressure is low in the asthenic stage.
In dengue we do not have the rise in blood pressure but the slow pulse is quite a feature of many of the dengue-like fevers.
In blackwater fever the pulse is rapid and soon becomes weak and of low tension.
Plague shows a striking toxic action on the heart muscle so that we soon get a soft, dicrotic pulse, rapid from the first and soon becoming thready. Patients with plague may die from cardiac failure upon getting up from bed.
A rapid pulse, especially in the morning, is thought to be a feature of active leprosy.
In cholera the pulse is rapid and feeble during the stage of evacuation and with the onset of the algid stage we practically have a cessation of the circulation. The systolic pressure may fall as low as 65 or 70 mm.
Hookworm anaemia shows early and marked cardiac palpitation. The pulse rate averages about 110 and the blood pressure is low. There is often some right-side dilatation of the heart.
Malaria generally gives a small, rapid, high tension pulse in the cold stage to become full and bounding in the hot stage. A cardiac type of pernicious malarial fever has been described, particularly by the French.
Both Malta fever and bacillary dysentery tend to have a toxic effect on the heart.