As to the reasons why these infections occur we have to consider several things. These syndromes are notoriously associated with paratyphoid, but paratyphoid is, by no means, not the only thing which can cause them. It is, in fact, the most common cause, but we know from culturing many of these eggs/babies that other bacteria often are implicated. Salmonella is a fickle organism and sometimes it will not grow on culture, but it is in fact still the underlying culprit. We, instead, culture secondary invaders. It is impossible to know if this is the case in all, or if the usual secondary invaders are primary causes of the syndrome. I feel that frequently other bacteria are in fact primary disease producers in many of these cases.

When we see an inordinate number (an epidemic) of this we suspicion paratyphoid because of the statistical odds that salmonella is the pathogen. We also know that other bacteria can cause similar syndromes. These other bacteria, in what I believe is the frequency of occurrence, are Pseudomonas spp., Proteus spp., E.coli, Klebsiella spp., and Citrobacter spp. Of these Pseudomonas can be the most difficult to treat because it is notoriously resistant to many antibiotics.

When it becomes pandemic, i.e. involving virtually all of the babies one must think of loft contamination. Loft contamination implies that the numbers of bacteria in the loft environment has become so high that it is virtually impossible to escape infection, especially by the most susceptible. This happens because of prolonged periods of high humidity and mild to warm temperatures. This allows the bacteria to flourish in the enriched environment. We all know that dryness and very cold work against bacterial growth, and the opposite promotes their growth. With any infection an infective dose of bacteria is needed, so the higher the numbers of bacteria in the environment the easier it becomes for the infective dose to be achieved.