INFECTIOUS DISEASES. 5G9 



The cases of navel ill resiiltinf? from infection before birth can not 

 well he g^uanled a<;aini;t. liy keeping mares, advanced in pre«i:nancy, 

 in j^ood physical condition, the fetus will he expelled imiiied lately 

 upon the openings of the uterine cavity. 



Once the infection of the navel cord has set in, the cord sIkjuM not 

 be li<;ated hut should i)e washed in a disinfectant solution and a 

 veterinarian called for the subsequent treatment. 



INFECTIOUS ANEMIA OR SWAMP FEVER. 



liy .loHN K. ^loili.KK, V. M. !>., As.sixtant Chief, JiiiDnu of Aiiiiiial ] ndiislrii. 



Infectious anemia of horses, known also by a number of other 

 names, as swamp fever, American surra, malarial fever, typhoid 

 fever of horses, the unknown disease, no-name disease, i)lains paraly- 

 sis, and ix'rnicious anemia, has recently been the subject of much in- 

 vestijjation. The cause of the disease has now been definitely deter- 

 mined as an invisible virus, which is capable of j^assinj; throu«j:h the 

 pores of the finest porcelain filters, like the infection of foot-and- 

 mouth disease, rinderpest, hog cholera, and similar diseases. The 

 disease is most prevalent in low-lying and badly drained sections 

 of the country, although it has been found on marshy pastures dur- 

 ing wet seasons in altitudes as high as 7,500 feet. Therefore proper 

 drainage of infected ])astures is indicated as a preventive. It is 

 also more prevalent during wet years than in dry seasons. It usually 

 makes its appearance in June and increases in frequency until Oc- 

 tober, although the chronic cases may be seen in the winter, having 

 been contracted thuing the waini season. 



Cause. — It has been conclusively proved that infectious anemia is 

 produced by an invisible filterable organism which is transmissible 

 to horses, mules, and asses by subcutaneous inoculation of blood se- 

 rum. The virus which is present in the blood may be transmitted to 

 a number of equines in a series of inoculations by injecting either the 

 whole blooil, the delibrinated blood, or the blood serum which has 

 been passed through a fine Pasteur filter, thus eliminating all the 

 visible forms of organismal life, including bacteria, tryjianosoma, 

 I)ii-oplasma, etc. This virus has also been found to be active in the 

 carcass of an affected animal 24 hours after death. 



Following the injection of the infectious priniiple there is a peiiod 

 of incubation which may extend fiom ten days to one and one-half 

 months, at the end of which time the onset of the disease is mani- 

 fested by a rise of temperatui-e. If uncomplicated, the infection runs 

 a chronic lour.se, terminating in death in from two months to one 

 and onedialf years, or even longer. The probability of the virus 

 being spread by an inteiinedi;ite host, sinh as (lies. nio;^(|uiioes, inter- 

 nal parasites, etc., is now receiving careful investigation. 



