THE UNITED STATES By ERNEST CARROLL FAUST
The William Vincent Professor of Tropical Diseases and Hygiene Department of Tropical Medioine and Public Health, Tulane
University of Louisiana, New Orleans
In 1916 Kofoid and McCulloch reported the 6nding of a trypanosome (Trypanosoma triatomae nsp.) in the digestive tract of the cone-nosed bug, Triatoma protracta, which had been collected from nests of the wood rat, Neotoma fuscipes macrotis, in the vicinity of San Diego, California. Although these workers recognized the remarkable similarity between the crithidial and trypanosomal stages of this flagellate and the same stages of T. (ve1 SchizotTpanum) cruzi, their failure to 6nd the parasite in the blood of the wood rat lead them to describe the species as new. In 1933 Kofoid and Donat succeeded in infecting albino rats and the opossum (Didelphz’s virginiana) with T. triatomae by intraperitoneal in- jection of the intestinal contents of naturally infected T. protracta from San Diego. Moreover, after allowing clean T. protracta from Berkeley, California to feed on the infected laboratory mammab, the infection was reëstablished in this bug. In view of the identical morphological and life-cycle characteristics Kofoid and Donat (i.c.) concluded that the California triatomid was T. cruzi, and that T. triatomae Kofoid and McCulloch lapsed as a synonym of T. cruzi Chagas, 1909. In a separate communication Kofoid and Donat (1933) reported the successful inocu- lation of the northern subspecies of the dusky-footed wood rat (Neotoma fuxipes annectens) with T. cruzi. Soon thereafter Fay Donat Wood (1934) discovered natural infection of T. cruzi in the San Diego wood rat (iV. fuscipes macrotis) and obtained experimental infection in five species of deer mice (Peromyscus spp.) native to California. Kofoid (1934) sum- marized the California findings and added the datum that N. fuscipes macrotis had been experimentally infected.
In 1936 Kofoid and Whitaker added a second species of naturahy in- fected triatomid to the North Ameritan list, namely Eutriatoma uhireri (ve1 T. rutida), collected from the vicinity of Tucson, Arizona. In 1938 S. F. Wood found naturally infected T. protracta in a collection of bugs made near Pasadena, California and in 1941 in a collection from Tyrone, Grant Co., New Mexico. Likewise this investigator discovered natural infection in T. longipes (1941) near Congress, Yavapai Co., Arizona, in E. uhleri from the same locality (1943) and in E. uhleri from Sanderson, Texas (1943). Meanwhile Packchanian had incriminated T. gerstaeckeri as a natural host at Three Rivers, Live Oak Co., Texas (1939) and T.
456 BULLETIN OF THE PAN AMERICAN SANITARY BUREAU TABLE l.-Blood-Sucking Bugs as BioEogical Vectors of Trypanosoma cruzi in the
United States
NAME
A. Infected in Nacture Triatoma protracta
“ “
“ “
Eutriatoma uhleri (ve1 T. rubida)
“ “
T. tongipes T. gerstaeckeri
‘< “
T. protracta woodi T. heidemanni E. uhleri T. sanguisuga
T. sanguisuga ambigua T. neotomae
T. longipes T. rubida T. protracta
<< LL
T. protracta woodi T. uhleri
B. Experimentally Infecte T. protracta
X. sanguisuga ambigguc. X. heidemanni
T. indictiva T. neotomae
.-
< ->an Diego, California
Pasadena, California ryrone, Grant Co., N.
Mexico Tucson, Arizona Congress, Yavapai Co.,
Arizona
“ L‘
Three Rivers, Live Oak Co., Texas
Maverick Co., Texas Brewster & Mavericl
Cos., Texas
Temple and Three Riv- ers, Texas
Sanderson, Texas Matagorda and Dimmit
Cos., Texas Uvalde Co., Texas Camcron & Willacy
Cos., Texas
Nogales, Santa Cruz Co Arizona
“ I‘
Continental, Pima Co Arizona
Nogales, Santa Cruz Co Arizona
Casa Grande, Pina1 Co., Arizona
Pima and Pina1 Cos., Arizona
d l.
California Sarasota, Florida Texas
Texas
Atlanta, Georgia - LOCALITY - .- I ( I k .t *> .> - AUTEOllITX
Kofoid and McCulloch, 1916
Kofoid and Donat, 1933 3. F. Wood, 1938 3. F. Wood, 1941
Kofoid & Whitaker, 1936 5. F. Wood, 1943 S. F. Wood, 1941 Packchanian, 1939 S. F. Wood, 1941 S. F. Wood, 1941 Packchanian, 1940 S. F. Wood, 1941 Davis et at., 1943 “ “ “ “ de Shazo (in Thurman,
1944) Schuck, 1945
“ ‘< S. F. Wood, 1949
L‘ “ <‘
“ “ ‘L
“ I‘ “
F. D. Wood, 1934 Packchanian, 1940 S. F. Wood, 1941 “ LL << “
Weinstein and Pratt, 1948
natural infection in T. gerstaeckerifrom Maverick Co., and in T. protracta woodi from Brewster and Maverick Cos., Texas. In 1943 Davis, McGregor and de Shazo discovered natural infection of T. sanguisuga in Matagorda and Dimmit Cos., and T. sanguisuga ambigua in Uvalde Co., while de Shazo (Thurman, 1944) incriminated T. neotomae in Cameron and Willacy Cos., Texas. Schuck (1945) and S. F. Wood (1949) have provided evidente of additional natural infections in Arizona. Thus, published data demonstrate that triatomids have been found naturahy infected with Trypanosoma cruzi in two counties of southern
California, in one county of southern Arizona and one of central Arizona, in the southwesternmost county of New Mexico and in eleven counties in the southern half of Texas. Limited surveys and collections in Utah have provided negative results (S. F. Wood, 1942). Table 1 summarizes the published data on naturally and experimentalIy infected triatomids ín the United States.
In addition to the original record of natural infection of Neotoma fuscipes macrotis in southern California, four species of mammals in Texas have been found naturally infected, viz., the nine-banded arma- dillo (Dasypus novemcinctus texanus), the Mid-Ameritan opossum (Di- del-phis marsupiaìis mesamericanus), the small-footed wood rat (Neotoma micropus micropus) and the domestic mouse (Packchanian, 1942). Ex- perimentally, in addition to the opossum, the albino rat and the albino mouse, five species of California deer mice and two subspecies of Neotoma fuscipes in California, the following North Ameritan mammals have been demonstrated to be suitable hosts of T. cruzi: N. micropus micropus in Texas (Davis, McGregor and de Shazo, 1943), Peromyscus eremicus in Texas (Packchanian, 1939; Davis et aE., 1943), the guinea pig (Pack- chanian, 1939), the rhesus monkey (Kofoid, 1934; Packchanian, 1939, 1940) and the domestic dog (Kofoid, 1934). S. F. Wood (1949) has demonstrated additional natural infections in Arizona (in Neotoma albigda alb<guEa and Peromyscus boylii rowleyi) by Xenodiagnosis, using laboratory-bred Triatoma protracta. The data on naturally and ex- perimentally infected mammals are summarized in Table 2.
There is no substantial published evidente of Chagas’ disease occurring in man as a res& of natural exposure withm the United States. In 1942 a large number of complement fixation tests were performed on residents of Texas, employing antigen prepared from a Panamanian strain of T. cruzi. Altogether 1,909 samples of serum were tested, of
458 BULLETIN OF THE PAN AMERICAN SANITARY BUREAU specimens of T. gerstaeckeri collected in the vicinity were found to be in- fected, physical examination of the boy and inoculation of Peromyscus sp. with blood freshly drawn from him failed to provide actual evidente of infection (Davis and Sullivan, 1946).
TABLE Z.-Mammalian Reservoir Hosts oj Trypanosoma cruzi in the United States NAW3
A. Infected in Nature Neotoma juscipes ma-
crotis
Dasypus novemcinctus texanus
Didelphis marsupial6 mesamericanus Neotoma micropus mi-
cl-opus Mus musculus N. albigula albigula Peromyscus boylii rowleyi B. Experimentally In-
fected
Rattus norvegicus (al- bino)
Mus musculus (albino: 6‘ <‘ <c ‘L << ‘C Neotomajuscipes annet
tens
N. juscipes macrotis N. micropus micropus N. albigula albigula
Peromyscus (5 species: P. eremicus
Guinea pig Didelphis virginiana Macaca mulatta
‘1 <‘ Canis jamiliaris
- -
1
:-
1
-
LOCALITY AUTEORIIY
ro. California ?. D. Wood, 1934
rexas ?ackchanian, 1942
havis Co., Texas “ “
rexas LL <‘
Live Oak Co., Texas santa Cruz and Pima
Cos., Arizona Santa Cruz and Pira
Cos., Arizona
<‘ L‘
3. F. Wood, 1949 3. F. Wood, 1949
California Kofoid and Donat, 1933 “
Texas
Atlanta, Georgia Central California
F. D. Wood, 1934; S. F. Wood, 1949
Packchanian, 1939, 1949 Weinstein and Pratt, 1948 Kofoid and Donat, 1933 So, California
Texas Arizona California Texas
“ California
t< Texas California
Kofoid, 1934 Davie et al., 1943 S. F. Wood, 1949 F. D. Wood, 1934; Kofoid, 1934; S. F. Wood,
1949
Packchanian, 1939 Davis et al., 1943 Packchanian, 1939 Kofoid and Donat, 1933 Kofoid, 1934
Packchanian 1939, 1940 Kofoid, 1934
Attempts to demonstrate natural or experimentally induced infection of Trypanosoma cruzi in bats in the United States have proved unsuc- cessful. Dias (1937) first found a trypanosome in a bat in North Amer- ica, (Antrozous pallidus paczj%us). AIthough closely resembling T. cruzz’, this trypanosome is regarded by Dias (personal communication, 1948) as belonging to the T. vespertilionis group. S. F. Wood (1941) in an ex- amination of 212 bats belonging to ten species, reported trypanosomes from five, viz., one Myotis veìifer velifer from Yuma Co., Arizona, three Pipistrellus hesperus maximus from Brewster Co., Texas and one Myotis occuZ¿us from Riverside Co., California. These trypanosomes appeared identica1 with T. vespertilionis.
S. F. Wood (Le.) has failed to infect bats by having them take blood meals from T. cruzi-infected bugs.
The extensive distribution of the etiologic agent of Chagas’ disease throughout the southwestern United States and the high percentage of triatomid bugs (seven species and two additiona1 subspecies) which have been found to be naturahy infected raise the question as to the public health significance of this infection in so far as the United States is con- cerned. The reasons for lack of convincing evidente concerning aut,och- thonous human infection are thus far largely unexpIained. In California human exposure is very limited, although wood rats and triatomids do enter human habitations (Kofoid and Whitaker, 1936). In some areas, as in the population along the Mexican border from Nogales, Arizona to De1 Rio, Texas, a considerabIe proportion of the population Iive in huts infested with triatomid bugs. In several of these areas Iarge numbers of the bugs have been found infected with T. cruzi. A question which is suggested is this: are the bugs which have been incriminated in the United States primarily zoöphilous or wiI1 they with equal freedom take human blood. S. F. Wood (1941) found that triatomids in certain years developed to plague proportions in Arizona, New Mexico and Texas. At such times they produced ahnost intolerabIe annoyance from their bites. If the bugs ordinariIy prefer animal bIood, then careful surveys should be made to determine whether the sources of mammalian blood are domestic or wild, or whether the bugs migrate from one place to an- other depending on climatic and edaphic conditions.
460 BULLETIN OF THE PAN AMERICAN SANITARY BUREAU periodic spraying of shelters and huts, to reduce the infestation and thus to minimka the possibility of human exposure.
REFERENCES
Davis, D. J.; McGregor, T.; and DeShazo, T.: Triatoma sunguisuga (Le Conte) and Triutoma ambigua Neiva as natural carriers of Trypanosoma cruzi in Texas, Pub. Health Rep., b8,353-354,1943.
Davis, D. J., and Sullivan, T. Des.: Complement-flxation tests for Ameritan trypan- osomiasis in Texas, Pub. Health Rep., 61,1083-1084,1946.
Dias, E.: Trypanosomes in bat and marmot, Trans. R. Soc. Trop. Med. & Hyg., 61, 260, 1937.
Kofoid, C. A.: Ameritan Trypanosomiasis. The northward extension of Brasilian trypanosomiasis, or Chagas’ disease, among mammals in California, Proc. 5th Pacific Sc. Cong., 30753078,1934.
Kofoid, C., and Donat, F.: The experimental transfer of Trypunosoma cruzi from naturally infected Triatomu protracla to mammals in California, Univ. Calif. Pub. Zool., 86, 257-259, 1933.
Kofoid, C. A., and Donat, F,: Experimental infection with Trypunosoma cruzi from intestineof cone-nosed bug, Triatoma protracta, Proc. Soc. Exp.Biol.Med., SO. 489-491, 1933a.
Kofoid, C. A., and McCulloch, 1.: On Trypanosoma triatomae, a new flagellate from a hemipteran bug from the nests of the wood rat Neotomu fuscipes, Univ. Calif. Pub. Zool., 16,113-126,1916.
Kofoid, C. A., and Whitaker, B. G.: Natural infection of Ameritan human trypanoso- miasis in two species of cone-nosed bugs, Triutoma protractu Uhler and Triatoma uhleri Neiva, in the Western United States, Jour. Parasit., ,%, 259-263,1936.
Packchanian, A.: Natural infection of Triatoma gerstakeri with Trypanosoma cruzi in Texas, Pub. Health Rep., 6.4, 1547-1554, 1939.
Packchanian, A.: Natural infection of Triatoma heidemanni with Trypanosoma cruzi in Texas, Pub. Health Rep., 66, 1390-1306, 1940.
Packchanian, A.: Experimental transmission of Trypunosoma cruzi infection in ani- mals by Triatoma sunguisugu ambigua, Pub. Health Rep., 66, 1526-1532, 1940.
Packchanian, A.: Reserve5 Hosts of Chagas’ Disease in the State of Texas. Natural infection of Nine-Banded Armadillo (Dasypus novemcinctus tezanus), House Mice (Mus musculus), Opossum (Didelphis virginiana), and Wood Rats (Neotomu micropus micropus), with Trypanosomu cruzi in the State of Texas, Am. Jour. Trop. Med., %?, 623-631,1942.
Packchanian, A. : Infectivity of the Texas strain of !&ypunosoma cruzi to man, Am. Jour. Trop. Med., &b, 309-314, 1943.
Packchanian, A.: The problem of Chagas’ diiease in Texas, Texas State Jour. Med., 4.9, 179-183, 1947.
Schuck, B. R.: A new locality for Trypanosoma cruzi in Arizona, Jour. Parasitol, si, 151, 1945.
Thurman, Jr., D. C.: The biology of Triatoma neotomae Neiva in Texas, Jour. Econ. Entomol., 97,116,1944.
Weinstein, P. P., and Pratt, H. D.: The laboratory infection of Triutoma neotomae Neiva with Trypunosoma cruzi Chagas and subsequent transmission to white mice, Jour. Parasitol., 54(3), 231-236,1948.
Wood, F. D., and Wood, S. F. : Present knowledge of the diitribution of Trypanormna cruzi in reservoir animals and vectors, Am. Jour. Trop. Med., M,335-345, 1941.
Wood, S. F.: New localities for Trypanosoma cruzi Chagas in Southwestern United States, Am. Jour. Hyg., 34, l-13, 1941.
Wood, S. F.: Observations on vectors of Chagas’ diiease in the United States. 1. California, Bull. South. Calif. Atad. Sc., Q1(2), 61-69,1942.
Wood, S. F.: The persistence of Trypanosoma cruzi in dead cone-nosed bugs (Hemip- tera, Reduviidae), Am. Jour. Trop. Med., %?, 613-621,1942a.
Wood, S. F.: Observations on vectors of Chagas’ disease in the United States. II. Arizona, Am. Jour. Trop. Med., %3,315-320,1943.
‘Wood, S. F.: Additional observations on Trypanosoma cruzi Chagas, from Ari- zona in insects, rodents and experimentally infected mammals, Am. Jour. Trop. Med. 99,43-53, 1949.
AGENTE ETIOL6GICO DE LA ENFERMEDAD DE CHAGAS EN ESTADOS UNIDOS (Sumario)
En 1916 Kofoid y McCulloch informaron sobre el hallazgo de un tripanosoma (7’. triatome n. sp.) en el tubo digestivo de triatomas capturados en nidos de ratas silvestres en la vecindad de San Diego, Cal. En experiencias realizadas en 1933, Kofoid y Donat hicieron inoculaciones animales comprobando que el parásito era idéntico al T. cruzi y que podía infectar la rata silvestre y Kofoid y Whitaker en 1936 encontraron el Entriatoma uhleri naturalmente infectado con tripanosomas, en la vecindad de Tucson, Arizona. Posteriormente otros investigadores han informado sobre diversos triatomídeos infectados naturalmente, con T. cruzi en California, Arizona, Texas y Nuevo Mdxico. Además del huésped originalmente descrito en el sur de California (Neotoma fuscipes macrotis) se han encontrado infectados 4 mamíferos de Texas : Dasypus novemcinctus texanus, Didelphis mar- supialis mesamericanus, Neotoma micropuus micropus y la rata dom&tica, lista a la que hay que agregar otros animales silvestres y domkticos descritos con infección natural. Considera el A. que no existen pruebas fundamentales de Ia. existencia en Estados Unidos de la enfermedad de Chagas en el hombre como resultado de estas infecciones animales naturales.
En 1942 se realizaron numerosas pruebas de fijaoi6n del complemento en resi- dentes de Texas, empleando antígeno preparado con una cepa panameña de T. cruzi. Entre 1,909 muestras de sangre ensayadas, solamente un muchacho de 8 años dió fijación del complemento en dilución significativa, perosu examen clínico yxenodiagnósticofueronnegativos. En 194Ose publicó una infección accidenta1 en Texas, lo que evidencia que esa cepa de tripanosoma es capaz de infectar al hom- bre. Las diferentes tentativas para demostrar la infección en murciélagos han sido infructuosas.
