Salmonellosis – a global infection

The Western Balkans are in fear after inspectors in Croatia discovered salmonella in some animal-derived food products on the shelves of local supermarkets. Tons of chicken have been withdrawn from retail chains. Citizens are alarmed, producers and traders are suffering enormous damage, and the first lawsuits due to these failures are expected.

Authorities in Bosnia and Herzegovina are reassuring citizens that controls at border crossings into the country have been intensified since the problem was noticed in neighbouring Croatia. They claim that such meat is not present in BiH, or has not yet been detected. If anyone attempts to import suspicious shipments into the country, they will be stopped.

What salmonella is, how it is transmitted, and how this infection can be prevented is explained for the Patria news agency by Dr. Tarik Bajrović, professor at the Faculty of Veterinary Medicine in Sarajevo.

Written by: Prof. Dr. Tarik Bajrović 

Salmonella are facultative anaerobic bacteria originating from food of animal origin, and among domestic animals, pigs and poultry are the primary sources of infection and the most common carriers for humans, but also from humans to humans and from humans to animals.

Water is a permanent source of infection, and besides domestic animals, wild animals, birds, and waterfowl are also significant.

In organically polluted waters and soil, they can survive for a long time, especially in winter, while in clean waters they can persist for about seven days.

In milk and other food products, they can multiply in large numbers. 

A temperature of 56 degrees Celsius kills them quickly, and they are very sensitive to chlorine. All salmonella cause damage to the infected organism through their endotoxins.

The first salmonella, the typhoid bacillus, was discovered in 1880 by Eberth in the spleen and lymph nodes of a patient who died of typhoid fever.

Latent or active carriers excrete the pathogen through faeces, and the prevalence (the proportion of the population affected by the disease) varies by country of origin, so in the USA and Australia it is about 7 percent, while in Europe it ranges from 1 to 42 percent. In Sweden, for example, the prevalence of salmonellosis in food obtained from animals is low, given that control programmes have been implemented since 1961, and since 1995 these programmes have included cattle, pigs, and poultry for slaughter.

The link between diseased cattle and humans is explained by the use of antimicrobial preparations in cattle and the consequent emergence of resistant strains, which are equally reported by both developed and developing countries.

Human salmonellosis presents in two clinical entities: First, enteric fever caused by S. typhi or S. Paratyphi A, B, or C. Second, "non-typhoidal salmonellosis" caused by other serotypes of salmonella that reside in animals and have zoonotic potential.

Today, the drugs of choice for humans with an acute course of the disease are considered to be Fluoroquinolones.

In most developed countries of the world, prophylactic action is taken with antibiotics (oxytetracyclines) through food or water, and control programmes of serological testing of milk sera to detect antibodies and thus salmonellosis as a disease are particularly attractive. Denmark has set a long-term goal of reducing the prevalence of salmonellosis by introducing the At ELISA test with bulk tank milk every three months and blood serum every three years.

Such measures for detecting carriers are considered much more effective than previous ones that involved testing fish, meat, or bone meal, although that is not negligible either, but it is too late to change anything in the case of positive test results.