In some of the countries of the Orient smallpox kills more people than cholera, plague and dysentery together. Many reports have shown that as many as 80 to 90% of a native population may be attacked in an outbreak and of these practically one-half die. In such communities the disease is more one of young children, the adults possessing a certain degree of immunity from attacks in childhood during previous epidemics. It has frequently been noted that the native colored races do not seem to acquire as marked an immunity as is observed among the white races of temperate climates following an attack of the disease. Again it has been insisted that the immunity following vaccination is not as marked as that obtaining in European countries. This point would seem not well founded because efficient and universal vaccination has apparently caused smallpox in the Philippines to be of no more importance than it is among any other well vaccinated people. It is striking to note the great number of pitted faces among adult Filipinos, whereas this condition is practically absent in the generation following the general vaccination introduced by the Americans.
In tropical natives the most severe forms of smallpox are observed—confluent and haemorrhagic.
Opportunities for the spread of the disease are most favorable in many parts of the tropical world by reason of intimate association, religious festivals and pilgrimages.
Under the name alastrim or Kaffir milk-pox, a disease similar to a mild form of smallpox has been reported from Africa and the West Indies. Various points were raised to differentiate it from smallpox, but in a recent epidemic in Jamaica and Haiti proof was adduced to demonstrate its identity with smallpox. In Haiti the epidemic was controlled by vaccination with smallpox vaccine, and those individuals exposed to the infection but properly vaccinated, uniformly escaped. Among the soldiers of the Marine Corps in Haiti there were only two cases and these occurred in men who gave no evidences, of successful vaccination.
Varicella.—This disease is of common occurrence in the tropics and does not seem to give rise to greater mortality than it does in temperate climates.
In the Philippines I have been struck by the resemblance it bears to cases of varioloid, inasmuch as we frequently note as numerous lesions on the face as on the body. In fact I have been sure that the pustular lesions of the face of such cases were those of smallpox, until I noted typical varicella lesions on the body.
Mumps.—This disease is found in many parts of the tropics and presents similar features to the epidemic parotitis of temperate climates.
In the Philippines there seem to be cases similar to mumps but without the contagious feature so characteristic of the disease in Europe.
Glanders.—This rare disease of Europe and the United States seems to be much more common in many tropical countries. In the Philippines it generally shows itself in the acute form and is much dreaded by reason of its great infectiousness.