With the elimination of smallpox, it has become important to identify and characterize other orthopox viruses which can infect human beings and cause diseases resembling small pox.
I. Monkey pox:
    1. The virus was first isolated in 1958 from an outbreak of pox disease in a captive monkey colony.
    2. Similar outbreaks were seen in other monkey colonies also.
    3. The first human case was reported in Zaire in 1970.
    4. Central and West Africa also found to bear some outbreaks.
    5. Clinically it resembles small pox.
    6. Rarely, it is transmitted from one person to another.
    7. Widespread natural infections occurred in monkeys of Africa.
II. Buffalo pox:
    1. Identified in cattle in India in 1934, and considered as an outbreak of Vaccinia.
    2. The disease spread among buffalos, and person who had close contact with infected animals had lesions on the hands.
    3. Buffalo pox is still persisting, being different from Vaccinia and Variola.
    4. Vaccines for small pox does not provide protection from buffalo pox.
III. Cowpox:
    1. Both the infections are acquired from cows.
    2. Cowpox lesions are seen on the udder and teats of cows.
    3. Transmitted to humans during milking.
    4. Lesions in humans appear on the hands or fingers.
    5. The disease is accompanied by fever.
    6. Fatal outbreaks had been reported in wild animals kept in zoos.
    7. Elephants and cheetah’s were affected the most.
    8. Natural infection had been reported in domestic cats.
    9. The primary host of cowpox may not necessarily be cows.
    10. Wild rodents and cats are even more susceptible.
IV. Milker’s nodes:
    1. It is an unimportant occupational disease.
    2. Humans get the disease during the milking of infected cows.
    3. Lesions occur as small nodules that are ulcerating.
    4. They cannot be grown externally in eggs.
    5. It is usually grown in bovine kidney cultures.
V. Orf (contagious pustular dermatitis):
    1. It is primarily the disease of the sheep and goats.
    2. Transmitted to humans by contact.
    3. In humans, the disease causes lesions which may be hardened and vesicular.
    4. The lesion may have a central ulcerating portion.
    5. Hands, forearms and face are the commonly effecting sites.
VI. Tanapox:
    1. The virus was isolated from the epidemics of a feverish illness, along the Tana river in Kenya.
    2. The patients showed scary like lesions on the upper parts of the body.
    3. Monkeys are the only susceptible animal.
    4. It is different from other types, that it cannot grow in eggs.
    5. Human and monkey tissue culture is used for growing.
VII. Molluscum contagiosum:
    1. The disease is commonly seen among children and young adults.
    2. Characterized by pink or pearl- like white nodules resembling warts on the skin.
    3. Eosinophilic inclusion bodies are seen in sections of lesions.
    4. They seem to displace the nuclei to the margin.        These bodies are known as Molluscum bodies.
    5. They are composed of large amounts of viral particles implanted in a protein matrix.
    6. Humans are the only susceptible hosts.
    7. The virus cannot be grown in eggs, tissue culture or animals.
    8. The incidence of this virus is found to be through sexual transmission.
    9. When it occurs in the genital areas, it may become inflamed, ulcerated , and create HSV infections.