242 Arthropod Transmission of Disease 
and for several hours within the gastro-intestinal tract. Mosquitoes 
and lice were found not to take up or maintain the virus. On the 
other hand, the bedbug ( Cimex lectularius) was found to take the 
virus from the infected monkeys and to maintain it in a living state 
within the body for a period of seven days. This was demonstrated 
by grinding up in salt solution, insects which had fed on poliomyeletic 
animals and injecting the filtrate into a healthy monkey. The experi¬ 
menters doubted that the bedbug is a carrier of the virus in nature. 
Earlier in the same year, Braes and Sheppard published the results 
of an intensive epidemiological study of the outbreak of 1911, in 
Massachusetts. Special attention had been paid to the possibility 
of insect transfer and the following conclusion was reached: 
“Field work during the past summer together with a consideration 
of the epidemiology of the disease so far as known, points strongly 
toward biting flies as possible carriers of the virus. It seems probable 
that the common stable-fly ( Stomoxys calcitrans L.) may be responsi¬ 
ble to a certain extent for the spread of acute epidemic poliomyelitis, 
possibly aided by other biting flies, such as Tabanus lineola. No 
facts which disprove such a hypothesis have as yet been adduced, 
and experiments based upon it are now in progress.” 
As stated by Braes (1913), especial suspicion fell upon the stable- 
fly because: 
1. The blood-sucking habits of the adult fly suit it for the transfer 
of virus present in the blood. 
2. The seasonal abundance of the fly is very closely correlated 
with the incidence of the disease, rising rapidly during the summer 
and reaching a maximum in July and August, then slowly declining 
in September and October. 
3. The geographical distribution of the fly is, so far as can be 
ascertained, wider, or at least eo-extensive with that of poliomyelitis. 
4. Stomoxys is distinctly more abundant under rural conditions, 
than in cities and thickly populated areas. 
5. While the disease spreads over districts quickly and in a 
rather erratic way, it often appears to follow along lines of travel, 
and it is known that Stomoxys flies will often follow horses for long 
distances along highways. 
6. In a surprisingly large number of cases, it appeared probable 
that the children affected had been in the habit of frequenting places 
where Stomoxys is particularly abundant, i.e., about stables, barn¬ 
yards, etc. 
