PUBLIC HEALTH CONCERN
Humans are usually resistant to acquiring infection, but when infected may show three different clinical forms: cutaneous, respiratory and intestinal.
The cutaneous form begins with the classic malignant pustule most often localized on the face, neck, arms, hands or legs.
This is usually seen in high-risk occupations such as farmers, butchers, tanners, wool carders, shearers and veterinarians. At the point of entry of the bacterium, usually a pre-existing scratch, there is a skin redness, which turns into a papule. Characteristically this lesion is not painful. The surrounding area appears hyperaemic and oedematous. The papule develops into vesicles that spontaneously, or from scratching, break, and eventually it is covered with a black eschar.Cutaneous anthrax is easily treatable with antibiotics, but if a pustule is neglected it may evolve into a fatal septicaemia. Untreated, approximately 10% of cutaneous cases result in death.
Intestinal anthrax results from the consumption of contaminated meat. The symptoms include nausea, loss of appetite, vomiting and fever followed by abdominal pain, vomiting of blood, severe diarrhoea, lesions and soreness in the throat, difficulty swallowing, and marked swelling of the neck and regional lymph glands. Intestinal anthrax results in death in 25 to 60% of cases(12). The intestinal form is less frequent and occurs in developing countries or in areas where there is limited food safety hygiene.
The respiratory or pulmonary form of anthrax is the major cause of atypical haemorrhagic pneumonia, starting with flu-like symptoms and characterized by fever, muscle pains, coughing, red nose and bloody sputum. Untreated cases are fatal. Respiratory function is compromised by mediastinal expansion, large pleural effusions, and haema- togenous and lymphatic vessel spread of B. anthracis into the lungs with consequent pneumonia.
The central nervous system and intestines manifest similar haematogenous spread, vasculitis, haemorrhages and oedema(13).SIGNIFICANCE AND IMPLICATIONS FOR ANIMAL HEALTH
In Italy, the European country in which anthrax has been most active recently, three main outbreaks involving domestic animals and humans during the last 14 years developed in areas inside the natural national parks. This epidemiological aspect results from a lack of removal of the carcasses of dead animals in wild areas, whereas in agricultural areas humans interrupt the cycle of B. anthra- cis by removing carcasses quickly. Thus wild areas could be considered the natural habitat of B. anthracis and the place of spore production. We can define ‘rural area’ as the zone located between agricultural and wild areas, where human activity is usually limited to the use of pastures. It represents the contact point between the wild and the agricultural worlds, and the habitat in which domestic and wild animals share the same areas. The proximity to the sources of production of anthrax spores, in the wild area, produces a level of contamination of soil, favouring the sequence of events that gives rise to the disease in domestic animals in this area.
In disease-endemic areas, susceptible wild animals could represent a potential amplification factor for B. anthracis spores and increase the probability of outbreaks in domestic animals and in humans. There is a need to evaluate the safety and efficacy of B. anthracis vaccines in wild animals, especially deer, and investigate the inclusion of wild ruminants in the anthrax prophylaxis programmes.