Category Archives: Infectious Diseases Tropical Medicine and Sexually Transmitted Diseases


The term bacteraemia refers to the transient presence of organisms in the blood (generally without causing symptoms) as a result of local infection or penetrating injury. The term septicaemia, on the other hand, is usually reserved for when bacteria or fungi are actually multiplying in the blood, usually with the production of severe systemic symptoms such as fever and hypotension. Pyaemia describes the ser

Pyrexia of Unknown Origin (PUO)

A major diagnostic problem is the patient who has a pyrexia, either intermittent or continuous, that lasts for 2 weeks or more and in whom routine investigations have failed to reveal a cause. Pl.l O may merely be an unusual presentation of a common disease.  formation box 1.1 shows some of the common causes of pua. Age is an important pointer, since cancer and the connective tissue diseases are more common


HISTORY Particular attention should be paid to the following: 1 Age of the patient 2 Foreign travel-remembering that certain diseases can exist both in the tropics and Europe, e.g. leishmaniasis, giardiasis 3 Immigrants-country of origin 4 Food and water-food poisoning is extremely common 5 Occupation, e.g. (a) Sheep farmers-hydatid disease (b) Sewer workers -leptospirosis (c) Leather workers-anthrax 6 Domestic p

Metabolic Consequences

Infection not only causes local damage but also has important generalized effects. Fever Body temperature is controlled by the thermoregulatory centre in the anterior hypothalamus in the floor of the third ventricle. This centre is sensitive to endogenouspyrogen (IL-1) which is released from a variety of cells involved in host defence, primarily blood monocytes and phagocytes, under the influence of microbial

Principles and Basic Mechanisms

Specificity Some infectious agents are strictly species selective. Amoebiasis, for example, only naturally affects humans. Even within a species, relative resistance is apparent, such as the decreased susceptibility of Duffy blood group negative individuals to Plasmodium vivax malaria. Microorganisms are also highly specific with respect to the organ or tissue that they infect. This predilection for specific


The prevalence of infectious diseases varies markedly throughout the world and depends on climatic conditions, sanitation, the quality of the water supply, and to some extent the specific disease resistance of the indigenous population at risk. The continuance of infectious diseases in a human population requires:\ • Reservoirs of infection • Effective modes of transmission Reservoirs HUMAN RESERVOIRS are

Global Impact

Infectious diseases are the commonest afflictions of humans and are a major source of morbidity and mortality in both developed and developing countries. Table 1.1 shows estimated morbidity and mortality figures for the common infectious diseases. Increase in world travel in the past 30-40 years has brought Westerners into contact with a number of diseases unusual in the West, such as malaria and schistosomia