Hantaviruses are evolutionarily closely connected to the certain rodent species of the families Cricetidae and Muridae (voles, mice, and rats). The viruses are spread mainly by coughing or sneezing. The sources of human infection are rodent carriers who shed the virus along with the excretions into the environment. There is a possibility of human infection through nutrition, namely the use of products that have not been heat treated (vegetables, bread, etc.) and which have been contaminated by rodents. The risk groups include the military, rural residents, urban industrial workers and employees, and tourists (hunting, fishing, picking mushrooms, berries, etc.). Sick people probably are not a source of infection. The natural reservoirs for the virus are voles (Apodemus agrarius) and Asian rats (Apodemus peninsulae). Seronegative forms of infection occur in no more than 1-4% of patients with HFRS. People who were ill with HFRS form a long-term, probably lifelong, immunity to Hantaviruses.
Giardiasis is a disease caused by a single-celled parasite Giardia lamblia, which is introduced into the tissues of the intestine. Giardiasis is common among children as well as among adults of certain categories, particularly among homosexuals, people who often visit developing countries, as well as patients with chronic pancreatitis and with low acidity of gastric juice, and people with removed stomach. Infection occurs through the transfer of cysts of the parasite from one person to another. Direct transmission occurs between children or sexual partners, while indirect – through dirty food and water. Giardiasis is revealed intermittently through nausea, increased flatulence (bloating), and diarrhea. Severe forms of the disease can break the absorption of food, which is manifested in the weight loss. Other symptoms depend on the order in which infestations occurred in parts of the intestine. Metronidazole and tinidazole are subscribed for the treatment of giardiasis (drugs are contraindicated during pregnancy.) The course of treatment also includes sparing diet containing a sufficient amount of animal protein and yeast.
Diphtheria is an acute infectious disease caused by a Leffler stick. Diphtheria bacillus is very stable in the environment and is resistant to drying. Microbes remain for a long time on linen, handkerchiefs, toys, clothing, and food and only can be killed when boiled, as well as under the influence of disinfectants. Children of all ages, including infants, can become ill. However, in the recent years, there is a tendency towards ill adults and older children. Severe forms of disease such as toxic and combined forms, mostly in unvaccinated children, may lead to the lethal outcome. People can contract this disease from the infected patients and from bacilli-carriers. Infection is transmitted by a droplet infection. However, people may also become infected through the care items, kitchenware, toys, as well as through the food, particularly milk products. Diphtheria immunity is unstable and can lead to the secondary cases. Children need to be vaccinated against diphtheria. However, vaccination cannot prevent the disease completely.
Cat scratch disease is an infectious disease that occurs after a bite or a scratch by cats. The disease proceeds with the formation of a primary affect in suppurating pimples with the subsequent development of a regional lymphadenitis. This infectious disease is probably caused by a virus, which is transmitted to humans through wounds on the skin from cat scratches, splinters or sharp object punctures. Traumatized skin becomes inflamed, and after a week, a person feels fever, and lymph nodes are swollen. In some cases, an abscess may develop, but usually there is a complete recovery. The incubation period is 3 weeks. In order to prevent the disease, all the scratches or cat bites should be promptly disinfected. If the disease is still evolving, the patients should receive the anti-antisense drugs and vitamins.
Brucellosis is an infectious-allergic disease characterized by general intoxication, lesions of the musculoskeletal system, nervous and reproductive systems. Six species of Brucella, tiny bacteria, are known. The most toxic Brucellas are from goats and sheep. The less toxic is Brucella of cattle and pigs. A pathogen is stable in the environment and in food products (milk, cheese). Infection occurs during pet care or through micro damages of skin (in assistance during calving, lambing, etc.). Pathogen spreads through the bloodstream in a body, leading to the formation of foci in the various organs and systems. Prognosis for life is favorable, but the disease often leads to a partial disability.