Gc. H. F. Nuttall 
49 
Anderson and Goldberger {loc. cit.) found that monkeys which had 
recovered from typhus inoculation became immune against reinocula¬ 
tion with typhus virus; that human blood was infective for eight days, 
and monkey blood for 5-6 days after the onset of the attack. On 
epidemiological grounds they believed that lice, but not bugs and fleas, 
served as carriers. They did not convey typhus to monkeys by means 
of lice 1 . In a paper published a few days previously, Eicketts and 
Wilder (5. n. 1910, pp. 463-467) reported that they had communicated 
Mexican typhus to Macacus rhesus by an injection of blood drawn 
from a man on the eighth day of the disease; the monkey showed no 
eruption like that observed in man. 
Eicketts and Wilder (16. iv. 1910, pp. 1304-1307) next inoculated 
rabbits and observed a rise of temperature in these animals after 5-12 
days, no eruption occurring and the bacteriological examination being 
negative. The authors lay stress upon the need of immunity tests 
being carried out with animals that have merely shown fever followed 
by recovery. This test consists in inoculating the recovered animals 
a second time with virulent typhus blood—a negative result indicating 
that they have been rendered immune by the first (masked) attack. 
This test is especially necessary when dealing with animals which do 
not develop typical symptoms. They reported that they could not 
maintain the virus by passage through more than 2-3 monkeys, and in 
these animals the disease proved to be mild or abortive, so that they 
could reach no conclusions without resorting to the immunity test. 
They found human typhus blood to be infective for monkeys on the 
8-10th day of the attack. Gavino and Girard (1910, pp. 1-32), working 
independently, were able to transmit Mexican typhus from man to 
Ateles vellerosus by the inoculation of 3-5 c.c. of blood. The animals 
showed fever after an incubative period of 11-14 days, and, after 
recovery, were found to be immune to reinfection. The virus persists 
in human typhus blood up to the tenth day of the attack. They found 
that the guinea-fig is susceptible to typhus. 
Anderson and Goldberger (2. ii. 1912, pp. 149-160) demonstrated 
experimentally that “Brill’s disease 2 ” occurring in New York, is 
identical with “ tabardillo ” of Mexico and European typhus fever. 
They successfully infected monkeys {Macacus rhesus) with the blood 
1 Their suggestive observations on the distribution of lice and typhus in Mexico 
will receive mention in the following paper on the Biology of Pediculus humanus. 
2 Vide Brill, N. E. (1898), New York Med. Journ., lxvii. 48, 77; (rv. 1910) Am. Journ. 
Med. Sci. 
Parasitology x 
4 
