KOSEN 한인과학기술자네트워크

Trypanosoma cruzi의 감염에 의해 발생하는 질환으로는 Chagas' disease를 들 수 있습니다. 감염이 된 후 몇년이 지나서 extensive myocarditis가 발병되는 것으로 알려져 있고 Central and South America에서 가장 흔한 heart disease 중의 하나로 알려져 있습니다. 미국의 경우에도 이곳에서 이주하는 사람들로 인해 case가 증가하고 있다고 보고되고 있습니다. 나머지 Clinical Course, Diagnosis, Treatment, Prevention 등 자세한 내용은 아래의 HARRISON 내용을 참고하시길 바랍니다. 남미에서 오셔서 관심이 많으신것 같네요... 예전에 infection mechanism에 관련된 Cell 논문을 본 적이 있었는데 참 재미있다고 느꼈지요...치료제관련 내용은 Treatment를 읽어보시면 도움이 될 것 같습니다. 하시는 일 잘 되시고 궁금한점이 생기면 저도 여쭤볼께요...^^ Definition Chagas' disease, or American trypanosomiasis, is a zoonosis caused by the protozoan parasite T. cruzi. Acute Chagas' disease is usually a mild febrile illness that results from initial infection with the organism. After spontaneous resolution of the acute illness, most infected persons remain for life in the indeterminate phase of chronic Chagas' disease, which is characterized by subpatent parasitemia, easily detectable antibodies to T. cruzi , and an absence of symptoms. In a minority of chronically infected patients, cardiac and gastrointestinal lesions develop that can result in serious morbidity and even death. Life Cycle and Transmission T. cruzi is transmitted among its mammalian hosts by hematophagous triatomine insects, often called reduviid bugs. The insects become infected by sucking blood from animals or humans who have circulating parasites. Ingested organisms multiply in the gut of the triatomines, and infective forms are discharged with the feces at the time of subsequent blood meals. Transmission to a second vertebrate host occurs when breaks in the skin, mucous membranes, or conjunctivae become contaminated with bug feces that contain infective parasites. T. cruzi can also be transmitted by the transfusion of blood donated by infected persons, by organ transplantation, from mother to fetus, and in laboratory accidents. Pathology An indurated inflammatory lesion called a chagoma often appears at the parasites' portal of entry. Local histologic changes include the presence of parasites within leukocytes and cells of subcutaneous tissues and the development of interstitial edema, lymphocytic infiltration, and reactive hyperplasia of adjacent lymph nodes. After dissemination of the organisms through the lymphatics and the bloodstream, muscles (including the myocardium) may become heavily parasitized. The characteristic pseudocysts present in sections of infected tissues are intracellular aggregates of multiplying parasites. In the minority of persons with chronic T. cruzi infections who develop related clinical manifestations, the heart is the organ most commonly affected. Changes include thinning of the ventricular walls, biventricular enlargement, apical aneurysms, and mural thrombi. Widespread lymphocytic infiltration, diffuse interstitial fibrosis, and atrophy of myocardial cells are often apparent, but parasites are difficult to find in myocardial tissue. Conduction-system involvement often affects the right branch and the left anterior branch of the bundle of His. In chronic Chagas' disease of the gastrointestinal tract (megadisease), the esophagus and colon may exhibit varying degrees of dilatation. On microscopic examination, focal inflammatory lesions with lymphocytic infiltration are seen, and the number of neurons in the myenteric plexus may be markedly reduced. Accumulating experimental evidence implicates the persistence of parasites and the accompanying chronic inflammation—rather than autoimmune mechanisms—as the basis for the pathology in patients with chronic T. cruzi infection. Epidemiology T. cruzi is found only in the Americas. Wild and domestic mammals harboring T. cruzi and infected triatomines are found in spotty distributions from the southern United States to southern Argentina. Humans become involved in the cycle of transmission when infected vectors take up residence in the primitive wood, adobe, and stone houses common in much of Latin America. Thus human T. cruzi infection is a health problem primarily among the poor in rural areas of Mexico and Central and South America. Most new T. cruzi infections in rural settings occur in children, but the incidence is unknown because most cases go undiagnosed. Historically, transfusion-associated transmission of T. cruzi has been a serious public health problem in many endemic countries. However, with some notable exceptions, transmission by this route has been markedly reduced as effective programs for the screening of donated blood have been implemented. Several dozen patients with HIV and chronic T. cruzi infections who underwent acute recrudescence of the latter have been described. These patients generally presented with T. cruzi brain abscesses, a manifestation of the illness that does not occur in immunocompetent persons. Currently, it is estimated that 16 to 18 million people are chronically infected with T. cruzi and that 45,000 deaths due to the illness occur each year. Of chronically infected persons, 10 to 30% eventually develop symptomatic cardiac lesions or gastrointestinal disease. The resulting morbidity and mortality make Chagas' disease the most important parasitic disease burden in Latin America. In recent years, the rate of T. cruzi transmission has decreased markedly in several endemic countries as a result of successful programs involving vector control, blood-bank screening, and education of at-risk populations. A major program begun in 1991 in the “southern cone“ nations of South America (Uruguay, Paraguay, Bolivia, Brazil, Chile, and Argentina) has provided the framework for much of this progress. Uruguay and Chile were certified transmission-free in the late 1990s, and Argentina and Brazil are expected to follow suit shortly. Similar control programs have been initiated in the countries of northern South America and in the Central American nations. Acute Chagas' disease is rare in the United States. Five cases of autochthonous transmission and six instances of transmission by blood transfusion have been reported. T. cruzi was recently transmitted to three recipients of organs from a single T. cruzi–infected donor from Central America. In the past 30 years, more than a dozen instances of laboratory-acquired infection and imported cases of acute Chagas' disease were reported to the Centers for Disease Control and Prevention (CDC). Acute Chagas' disease has not been reported in tourists returning to the United States from Latin America. In contrast, the prevalence of chronic T. cruzi infections in the United States has increased considerably in recent years. Data from the 2000 census indicate that >12 million immigrants from Chagas'-endemic countries currently live in the United States, 8 million of whom are Mexicans. The prevalence of T. cruzi infection in Mexico is 0.5 to 1.0%, and most of the 4 million immigrants from Chagas'-endemic nations who are not Mexicans come from countries in which the prevalence of T. cruzi infection is greater than it is in Mexico. The total number of T. cruzi –infected persons living in the United States can be estimated reasonably to be 80,000 to 120,000. The number of instances of transfusion-associated transmission in this country is likely to be considerably greater than the number reported. Clinical Course The first signs of acute Chagas' disease develop at least 1 week after invasion by the parasites. When the organisms enter through a break in the skin, an indurated area of erythema and swelling (the chagoma), accompanied by local lymphadenopathy, may appear. Romaña's sign—the classic finding in acute Chagas' disease, which consists of unilateral painless edema of the palpebrae and periocular tissues—can result when the conjunctiva is the portal of entry (Fig. 197-1). These initial local signs may be followed by malaise, fever, anorexia, and edema of the face and lower extremities. A morbilliform rash may also appear. Generalized lymphadenopathy and hepatosplenomegaly may develop. Severe myocarditis develops rarely; most deaths in acute Chagas' disease are due to heart failure. Neurologic signs are not common, but meningoencephalitis occurs occasionally. The acute symptoms resolve spontaneously in virtually all patients, who then enter the asymptomatic or indeterminate phase of chronic T. cruzi infection. Symptomatic chronic Chagas' disease becomes apparent years or even decades after the initial infection. The heart is commonly involved, and symptoms are caused by rhythm disturbances, dilated cardiomyopathy, and thromboembolism. Right bundle-branch block is a common electrocardiographic abnormality, but other types of atrioventricular block, premature ventricular contractions, and tachy- and bradyarrhythmias occur frequently. Cardiomyopathy often results in right-sided or biventricular heart failure. Embolization of mural thrombi to the brain or other areas may take place. Patients with megaesophagus suffer from dysphagia, odynophagia, chest pain, and regurgitation. Aspiration can occur (especially during sleep) in patients with severe esophageal dysfunction, and repeated episodes of aspiration pneumonitis are common. Weight loss, cachexia, and pulmonary infection can result in death. Patients with megacolon are plagued by abdominal pain and chronic constipation, and advanced megacolon can cause obstruction, volvulus, septicemia, and death. Diagnosis The diagnosis of acute Chagas' disease requires the detection of parasites. Microscopic examination of fresh anticoagulated blood or of the buffy coat is the simplest way to see the motile organisms. Parasites also can be seen in Giemsa-stained thin and thick blood smears. Microhematocrit tubes containing acridine orange as a stain can be used for the same purpose. When repeated attempts to visualize the organisms are unsuccessful, polymerase chain reaction (PCR) or hemoculture in specialized media can be performed. When used by experienced personnel, all of these methods yield positive results in a high proportion of patients with acute Chagas' disease. Hemoculture has the disadvantage of taking several weeks to give positive results. Serologic testing plays no role in diagnosing acute Chagas' disease. Chronic Chagas' disease is diagnosed by the detection of specific antibodies that bind to T. cruzi antigens. Demonstration of the parasite is not of primary importance. In Latin America, 20 assays are commercially available, including several based on recombinant antigens. Unfortunately, these tests have varying levels of sensitivity and specificity, and false-positive reactions are a particular problem—typically with samples from patients who have other infectious and parasitic diseases or autoimmune disorders. In addition, confirmatory testing has presented a persistent challenge. For these reasons, it is generally recommended that specimens be tested in at least two assays and that well-characterized positive and negative comparison samples be included in each run. A highly sensitive and specific confirmatory method for detecting antibodies to T. cruzi[approved under the Clinical Laboratory Improvement Amendment (CLIA) and available in the author's laboratory] employs immunoprecipitation of radiolabeled T. cruzi antigens and electrophoresis. The use of PCR assays to detect T. cruzi DNA in chronically infected persons has been studied extensively.The sensitivity of this approach has not been shown to be reliably greater than that of serology, and no PCR assays are commercially available. Treatment Therapy for Chagas' disease is unsatisfactory. For many years, only two drugs—nifurtimox and benznidazole—have been available for this purpose. Unfortunately, both drugs lack efficacy and often cause severe side effects. In acute Chagas' disease, nifurtimox markedly reduces the duration of symptoms and parasitemia and decreases the mortality rate. Nevertheless, limited studies have shown that only 70% of acute infections are cured parasitologically by a full course of treatment. Despite its limitations, treatment with nifurtimox should be initiated as early as possible in acute Chagas' disease. Moreover, when laboratory accidents occur in which it appears likely that T. cruzi infection could become established, nifurtimox therapy should be initiated without waiting for clinical or parasitologic indications of infection. Common adverse effects of nifurtimox include abdominal pain, anorexia, nausea, vomiting, and weight loss. Neurologic reactions to the drug may include restlessness, disorientation, insomnia, twitching, paresthesia, polyneuritis, and seizures. These symptoms usually disappear when the dosage is reduced or treatment is discontinued. The recommended daily dosage is 8 to 10 mg/kg for adults, 12.5 to 15 mg/kg for adolescents, and 15 to 20 mg/kg for children 1 to 10 years of age. The drug should be given orally in four divided doses each day, and therapy should be continued for 90 to 120 days. Nifurtimox is available from the Drug Service of the CDC in Atlanta (telephone number, 770-639-3670). The efficacy of benznidazole is similar to that of nifurtimox; a cure rate of 90% among congenitally infected infants treated before their first birthday has been reported. Adverse effects include peripheral neuropathy, rash, and granulocytopenia. The recommended oral dosage is 5 mg/kg per day for 60 days. Benznidazole is generally considered the drug of choice in Latin America. The question of whether patients in the indeterminate or chronic symptomatic phase of Chagas' disease should be treated with nifurtimox or benznidazole has been debated for years. The fact that parasitologic cure rates in chronically infected persons are <20% is central to this controversy. Limited studies of T. cruzi–infected laboratory animals and humans suggest that elimination of the parasites reduces the appearance or progression of cardiac pathology. In view of these findings, an international panel of experts recommended that all patients infected with T. cruzi be treated with one drug or the other, regardless of their clinical status or the duration of infection. Considerable debate has followed this recommendation, and the issue remains unresolved. The usefulness of allopurinol, fluconazole, and itraconazole for the treatment of acute Chagas' disease has been studied in laboratory animals and to a lesser extent in humans. None of these drugs has exhibited a level of anti–T. cruzi activity that warrants its use in patients. Several newer antifungal azoles have shown promise in animal studies but have not yet been tested in humans. Studies in mice have shown that recombinant interferon decreases the duration and severity of acute T. cruzi infection; however, its usefulness in persons with acute Chagas' disease has not been evaluated systematically. Patients who develop cardiac and/or gastrointestinal disease in association with T. cruzi infection should be referred to appropriate subspecialists for further evaluation and treatment. Cardiac transplantation is an option for patients with end-stage chagasic cardiopathies, and >100 such transplantations have been done in Brazil and the United States. The survival rate among Chagas' disease cardiac transplant recipients is higher than that among persons receiving cardiac transplants for other reasons. This better outcome may be due to the fact that lesions are limited to the heart in most patients with symptomatic chronic Chagas' disease. Prevention Since drug therapy is unsatisfactory and vaccines are not available, the control of T. cruzi transmission in endemic countries must depend on reduction of domiciliary vector populations by spraying of insecticides, improvements in housing, and education of at-risk persons. As noted above, these measures, coupled with serologic screening of blood donors, have markedly reduced transmission of the parasite in many endemic countries. Tourists would be wise to avoid sleeping in dilapidated houses in rural areas in endemic countries. Mosquito nets and insect repellent provide additional protection. The question of whether blood donated in the United States should be screened for antibodies to T. cruzi has been considered by both public and private blood banking authorities for more than a decade. Since no assay for this purpose has been cleared by the U.S. Food and Drug Administration (FDA), serologic testing is not yet an option. Some blood-donor centers currently use a questionnaire to identify and defer donors at high risk for T. cruzi infection. The efficacy of this approach has not been assessed specifically, and it is important to bear in mind that approaches based solely on questionnaires have not been entirely successful at eliminating transfusion-associated transmission of other infectious agents. In view of the possibly serious consequences of chronic T. cruzi infection, it would be prudent for all immigrants from endemic regions living in the United States to be tested for evidence of infection. Identification of persons harboring the parasite would permit periodic electrocardiographic monitoring, which can be important because pacemakers benefit some patients who develop ominous rhythm disturbances. The possibility of congenital transmission is yet another justification for screening. Laboratory personnel should wear gloves and eye protection when working with T. cruzi and infected vectors. >안녕하세요, 전 남미에서 살다가 한국으로 돌아온지 얼마되지 않았습니다. 보다시피 생물학에 그중에서도 곤충에 대하여 어느정도의 관심을 가지고 있는데, 혹시 vinchuca domestica라는 점염병을 옴기는 곤 에 대하여서 들어 보셨는지? >병명의 이름은 Trypanosoma cruzi 라고 합니다. >이 곤충의 학문 이름은 Triatoma infestans입니다. 제가 알고싶은것은 이곤충이 전염시키는 병이 어떠한 질환을 일으키는지, 조기 치료가 가능한 약이 계발이 되었는지 알아 보고 싶어서입니다. >즐거운 주말을 보내시길 원하며, 이외, vinchuca에 대하여 공금한 점이 있으시다면 언제든지 질문하여(own-dae@hanmail.net) 주세요.

님, 님께서 올려 주신것보다 더 나은 인포메이션을 어느 사이트든지 찾을 수 있습니다. 영어보다 한글로도 구할수가 있는데... 저는 직접적으로 알고 있는 정보를 원하였는 것입니다. 이것으로 님께서는 관리를 중요시 하는것이나, 이벤트에 좀 기울어지셨다고 느낍니다. 질문의 노하우에서 적혀 있듯이; 질문하는 당사자의 질문을 찾아 적는것이 정당하고 이렇게 인터넷 사이트의 정보를 수정없이 올린다는것은 완지 어디가 급한듯 보입니다. 제가 님에게 거스르는 말이 아니라 이렇게 하시는게 좋을듯 합니다. 감사합니다. 여기 한 예를 올립니다. 제가 다른 사이트에서 찾은 것이죠. Triatoma infestans and other Triatomines - Biology The Triatominae are a subfamily of the Reduviidae, or assasin bugs. There are 118 known species (with sizes from 5 mm to 45 mm) and 14 genera. All are obligate bloodsuckers, regardless of age and sex. More than half of them were proven to have the ability to carry Trypanosoma cruzi, the flagellate that causes Chagas disease (Schofield & Dolling 1993 - see the literature list for complete references). Due to their biology and close association with humans, the most important vectors of Chagas disease are Triatoma infestans, Triatoma brasiliensis, Triatoma dimidiata, Triatoma sordita, Rhodnius prolixus, and Panstrongylus megistus (Schofield 1994). Host-finding of Triatomine bugs Triatomine bugs usually leave their refuge during the night to search for their host (Lent & Wygodzinsky 1979; Schofield 1979; Núñez 1987; Schofield & Dolling 1993; Schofield 1994). In different experimental setups Triatomine bugs were attracted using potential hosts such as a hamster (Núñez 1982), mice (Taneja & Guerin 1995, Rose & Boeckh 1996b), and humans (Rose & Boeckh 1996a/b). However, the role of individual stimuli such as heat and host odors, including carbon dioxide, is not entirely understood. Rose & Boeckh (1996a) demonstrated that breath is a major stimulus used in the orientation toward the host in Triatoma infestans. The work published so far has been conducted only in the laboratory. “The olfactory and thermal senses reside chiefly in the antennae, which serve also to perceive air currents and contact“ (Wiggelsworth & Gillet 1934). Mayer (1968) successfully recorded electrophysiological responses of singele cells in olfactory receptors on the antennae of Triatoma infestans towards breath, Bernard (1974) towards other host odors. Warmth Early findings by Hase (1932) with different species from Venezuela (Panstrongylus geniculatus, Rhodnius pictipes, and Eratyrus cuspidatus) already indicated that warmth is a major reason for the extension of the proboscis. Wiggelsworth & Gillet (1934) confirmed the dominant role of warmth for short distance orientation for Rhodnius prolixus. A warm test tube alone elicited probing. Nicolle & Mathis (1941) also reported probing responses towards warm bodies by Triatoma infestans and Rhodnius prolixus. Over a short distance, a warm current of air was shown to be attractive for already active Triatoma infestans and to elicit probing (Wiesinger, 1956). However, it did not activate resting animals. Núñez (1982) reported that nymphs of Rhodnius prolixus were not activated by warmth. In an olfactometer, they were only slightly attracted, compared to other host odors and carbon dioxide. This was interpreted as an indication that warmth plays only a smaller role in the orientation towards the host over longer distances. Lazzari & Núñez (1989) showed that Triatoma infestans nymphs are able to perceive radiant head and to distinguish between different temperatures of radiant heat sources. During his studies of olfactory sensilla of Triatoma infestans, Mayer (1968) did not find any response when he increased or decreased the temperature near the receptor. Lazzari & Wicklein (1994) recorded electrophsysiological activity of the so-called cave-like sense organ in the antennae of Triatoma infestans in response to thermal stimuli. Carbon dioxide The role of carbon dioxide was first investigated by Wiesinger (1956). She concluded that a warm (36 - 40 °C) mixture of carbon dioxide and air is more attractive for T. infestans than warm air alone, both in the activation and orientation responses towards the stimulus source. Núñez (1982) attracted nymphs of Rhodnius prolixus in an olfactometer with carbon dioxide. Rose & Boeckh (1996b) report similar findings for second instar Triatoma infestans. Both Triatoma infestans and Rhodnius prolixus also showed oriented responses towards carbon dioxide on a servosphere (Taneja & Guerin 1995). Guerenstein et al. (1995) were able to attract Triatoma infestans using an aerobic cultures of yeast on saccrose. The attraction of these cultures was reduced when the cabon dioxide realesed was partially eliminated using potassium hydroxide. A warm carbon dioxide source was shown to be attractive for nymphs of Triatoma infestans in an enclsure resembling the natural environment of the bugs (Rose & Boeckh 1996a). Mayer (1968) reports responses of olfactory sensilla towards carbon dioxide and carbon monoxide. However, these responses were not as strong as those towards breath. Other host odors Other host odors also seem to play a role in host orientation. Wiggelsworth & Gillet (1934) state that during their experiments, some bugs also oriented towards the test tube at room temperature when it was covered with a fresh mouse skin. However, they failed to probe it. No evidence was obtained of either attraction or repulsion by moisture. Núñez (1982) attracted nymphs of Rhodnius prolixus in an olfactometer using his fore arm. Hamster odors were still attractive when they were bubbled through a mixture of potassium hydroxide and water, thus removing both carbon dioxide and lactic acid. Indications that mice give off attractive odors are given by Torres-Estrada & Martínez-Ibarra (1993): They report that starving nymphs of Triatoma gerstaeckeri chose mice nests as a hiding-place, whereas fed animals preferred stone walls. Taneja & Guerin (1995) showed oriented responses of nymphs of Rhodnius prolixus and Triatoma infestans on a servosphere towards rabbit urine odors. Rose & Boeckh (1996b) attracted second instar Triatoma infestans using worn socks as a stimulus source. In 1997, Taneja & Guerin reported that ammonia at doses of 3 to 17 ppb attracted Triatoma infestans nymphs on a servosphere. They had detected ammonia both in stale rabbit urine odors as well as in wetted papers with triatomine feces. The olfactory sensilla studied by Mayer (1968) also showed responses to some chemicals associated with human breath odors (methanol, methane, furan, pyridine). However, these responses were not as strong as those towards breath. Bernard (1974) also reports electrophsiological responses of sensilla on the antenna of Triatoma infestans towards complex host odors (a finger, sweat), as well as individual chemicals such as lactic acid or butyric acid. Taneja & Guerin (1997) recorded electroantennograms as well as electrophysiological responses of single receptor cells in Triatoma infestans nymphs towards ammonia. Triatoma infestans (Klug 1834) Size: males 21-26 mm, females 26-29 mm. Distribution: From eastern and southern Brazil and the southern half of Bolivia down to the Argentinian province of Chubut. In all of Paraguay and the largest part of Uruguay. East of the Andes in northern Chile and southern Peru. In Bolivia, T. infestans was recorded to reach altitudes of 4100 m. The species is almost exclusively domestic and peridomestic. Sylvatic colonies are only reported from Bolivia, where they were associated with wild guinea pigs. But usually, the animals are found in human habitations, chicken houses, stables, enclosures or corrals.

샤가스병 (Chagas’disease) 샤가스병 (Chagas’ disease, American trypanosomiasis)은 브라질, 칠레, 아르헨티나, 우루과이 등 중남미에서 유행하고 있는 열대풍토병으로서 흡혈 빈대의 일종인 Triatoma 빈대 (kissing bugs, assassin bugs)에 의해 매개되는 원충성 질환이다. 원인 병원충인 크루스파동편모충 (Trypanosoma cruzi)은 1909년 말라리아 연구를 하던 브라질의 의사 Chagas에 의해 빈대의 후장 (資陽)에서 처음 발견되어 이 원충에 의한 질병을 샤가스병이라 한다. 샤가스병은 세계보건기구 (WHO)가 정한 관리대상 질병 중 말라리아, 주혈흡충증에 이어 3번째로 중요한 열대풍토병이며, 주로 남미의 농촌에서 유행하는 질병으로 여겨져 왔으나 농촌인구의 도시 이동으로 인해 도시지역에서도 점차 감염자가 증가하는 추세이다. 1. 역학 샤가스병은 전형적인 인수공통감염증(zoonosis)으로서 주로 야생동물과 빈대 사이에서 생활사(life cycle)를 이어가는데 미국 남부부터 멕시코, 아르헨티나, 칠레에 이르는 중남미 지역에 널리 분포한다. 샤가스병의 주요 감염경로는 매개곤충인 빈대에 물려서 감염되는 경우이며, 이외에도 감염자의 혈액을 수혈하거나 또는 감염된 산모를 통해 선천적으로 감염될 수 있다. 사람은 인가에 가까이 서식하는 빈대에 물려서 감염되는데, 사람을 흡혈하는 빈대로는 Triatoma infestans, Panstrongylus megistus, Rhodnius prolixus 등이 있다. 빈대는 주로 진흙으로 만든 벽돌 틈이나 야자수 지붕 등을 살면서 밤에 사람이 자고 있을 때 얼굴, 특히 눈이나 입 주위에 물어서 흡혈한다. 중남미 인구의 25%가 샤가스병의 감염위험에 폭로되어 있는데, 매년 100만명이 새로 감염되며 45,000명 이상이 사망한다. 현재 1,600-1,800만명이 감염되어 있는 것으 추정되는데, 이중 200-300만명은 만성 질환으로 이미 진행된 상태에 있으며, 300만명 이상이 잠복기 상태에 있는 것으로 추정하고 있다. 혈청학적 조사에 의하면 유행지역에서는 15-50%가 감염되어 있다. 농촌지역에 많고, 가난한 계층의 사람에서 감염률이 높으나, 브라질의 상파울루와 같은 도시지역의 경우 농촌에서 이주해 온 감염자들로 인해 수혈을 통한 감염 위험이 점점 증가하고 있어 매년 수 천명이 수혈로 인해 새로 감염되는 것으로 추정된다. 감염은 생후 수 개월에서 2세 사이의 어린이에서 제일 많다. 급성기 환자는 어린이에 많고, 증상이 심하지 않아 잘 찾아내지 못하는 경우가 많은 반면, 만성기는 어른에 많으며, 심장이나 소화관 침범이 흔하고, 산발적으로 발견된다. 만성 샤가스병의 발병은 연령적으로 변화가 많아서 브라질의 어떤 지역에서는 20대 초반에 많고, 파나마에서는 심장에 오는 후유증이 40세 이전에는 보기 힘들다. 또, 브라질에서는 거대결장증 (megacolon)이나 거대식도증(megaesophagus)이 많으나, 심근증(cardiomyopathy)은 베네수엘라, 콜롬비아에서 많이 관찰된다. 2. 형태 및 생활사 1) 형태 사람에서 관찰할 수 있는 크루스파동편모충의 발육단계는 trypomastigote와 amastigote, 두 종류이다. Trypomastigote는 크기가 20-25μm의 방추형으로 파동막과 편모를 가지며, 체 중앙에 1개의 핵이 위치한다. Amastigote는 크기가 1.5-4.0μm의 난원형으로 거의 모든 기관과 조직에서 증식한다. Trypomastigote는 말초혈액에서, amastigote는 주로 망상내피계, 심근을 비롯한 근육 및 신경세포 내에서 발견된다. 2) 생활사 Triatoma 빈대는 감염동물 또는 사람을 흡혈할 때 감염자의 혈액 중에 있는 trypomastigote가 빈대 체내로 들어옴으로써 감염된다. Trypomastigote는 빈대의 중장(中陽)에서 편모가 소실되면서 epimastigote로 되어 분열증식 한다. 점차 후장(後陽)으로 이동하면서 8-10일 후 metacyclic trypomastigote로 변형된 다음 대변과 섞여 있게 된다. 빈대는 흡혈할 때 대변을 배설하는데, 이때 충체도 대변과 함께 배출된 후 빈대에 물린 부위를 사람이 긁을 때 상처 부위를 통해 원충이 침입한다. 사람의 체내로 들어간 trypomastigote는 림프관을 따라서 타 장기로 가서 조직세포나 대식세포를 침입하여 세포 내에 기생하면서 amastigote로 변형되어 이분법으로 분열증식 한다. Promastigote, epimastigote를 거쳐 trypomastigote로 변형된 후 숙주세포가 파괴되면서 충체가 유리되면 혈류 내에 나타난다. Trypomastigote는 혈류를 따라서 여러 장기로 이행하여 다시 amastigote로 바뀌어 증식발육하면서 세포를 파괴하는 과정을 반복한다. 3. 병리 및 임상증상 1) 급성 샤가스병 빈대에 물린 부위는 국소 염증이 생기면서 융기되는데 이를 chagoma라 하며, 특히 한쪽 또는 양쪽 안검에 생긴 부종을 Romana’s sign이라 하고, 유행지역에서는 진단에 중요한 소견이 된다. 잠복기는 1-2주이며, 국소 림프절염과 함께 불규칙적인 고열, 오한, 전신권태, 근육통, 일시적인 피부 발진 등이 나타난다. 거의 모든 장기와 조직을 침범하여 여러 장기의 기능장애를 초래하게 되는데 간비대, 비장비대가 흔하게 나타난다. 급성기에는 치명적인 경과가 드물지만 심장을 침범하여 심근염, 심부전 또는 중추신경계를 침범하여 수막뇌염 등을 일으켜 사망할 수도 있다. 대개는 특별한 치료를 하지 않아도 수 주 내지 수 개월이 지나면 증상이 소실된다. 2) 만성 샤가스병 만성 경과는 주로 어른에서 관찰되는데, 심장과 관련된 증상이 제일 흔하게 관찰되어 심계항진, 어지러움, 실신 등과 같은 증상이 나타난다. 유행지역에서 외견상 건강하던 사람이 급사를 하는 경우가 드물지 않은데, 이는 샤가스병으로 인한 심실 부정맥에 기인한다. 흔히 심장의 신경전달계를 잘 침범하여 우각블록(right bundle branch block, RBBB)이 특징적으로 나타나기도 한다. 심부전은 주로 우심에 흔한데, 일단 생기면 수 년 내에 사망할 가능성이 높다. 크루스파동편모충은 자율신경절의 신경세포를 침범하므로 식도나 대장이 심하게 확장되는 거대식도증(megaesophagus) 또는 거대결장증(megacolon)이 흔하게 관찰 된다. 거대식도증이 생긴 경우 음식물을 삼키기 힘들거나 불편해지며, 흉골하 불쾌감(epigastric discomfort), 음식물의 역류(regurgitation) 등의 증상이 생기기도 한다. 한편, 거대결장증의 경우에는 만성 변비 또는 복통을 호소할 수 있다. 이외에도 빈혈이나 내분비 기능의 이상이 오기도 한다. 4. 진단 유행지역에서 빈대에 물린 경험의 유무가 진단에 중요한 정보가 된다. 그러나, 보통 관광과 같은 일반적인 여행의 경우로는 빈대에 물릴 가능성이 그리 높다고 할 수 없다. 급성기에는 말초혈액에서 trypomastigote를 검출할 수 있으며, 림프절 생검으로 진단하기도 한다. 또, 혈액이나 조직을 NNN 배지 (Novy, MacNeal and Nicolle’s medium)에 배양하면 많은 충체를 얻을 수 있으며, 의심되는 환자의 혈액, 림프절, 골수에서 채취한 가검물을 배양하거나 기니픽에 접종하여 충체를 검출하기도 한다. 한편, 만성기 환자와 같이 원충혈증(parasitemia)이 낮은 경우에는 곤충접종법(xenodiagnosis)으로 진단할 수 있는데, 이 방법은 실험실에서 키우고 있는 감염되지 않은 Triatoma 빈대를 피검자에게 물리고 30일 후에 충체를 검출 는 체외진단법이다. 이외에도 혈청 내 IgM을 검출하거나 심전도 소견도 진단에 도움이 된다. 5. 치료 Nifurtimox를 어른은 8-10 mg/kg, 어린이는 15-20 mg/kg을 3분복하여 90일간 경구투여한다. 또는 benznidazole을 어른은 5-7 mg/kg, 어린이(12세까지)는 10 mg/kg을 2분복하여 60일간 경구투여한다. 급성기에 투여하면 원충의 제거는 물론 치료가 잘 된다. 그러나, 60-90일 동안 장기간 투여해야 하므로 식욕부진, 메스꺼움, 구토, 복통과 같은 위장관계 증상이나 불면증, 불안감 등의 신경증상과 같은 부작용이 나타날 수 있다. 하지만 투약을 중단하거나 용량을 줄이면 부작용은 없어진다. 이미 심질환이 생긴 환자에서는 amiodarone과 같은 항부정맥 제제를 투여하거나 전기 심장 박동기로 증상을 호전시킬 수 있다. 거대식도증 또는 거대결장증의 경우에는 확장된 부위를 수술로 절제하여 증상을 호전시킬 수 있다. 6. 예방 매개곤층인 Triatoma 빈대의 방제가 가장 중요하고, 빈대에 물리지 않도록 조심하는 것이 좋다. 허술한 가옥을 위생적인 환경으로 개조하여 빈대가 서식하지 못하도록 하든지, 살충제를 살포하거나 방충망 안에서 생활하는 것이 좋다. 남미의 유행지역에서는 수혈에 의한 감염 위험이 있기 때문에 헌혈한 혈액에 대해서 선별검사를 실시하는 것이 바람직하다. 또는 사용 하루 전에 gentian violet을 1 : 4,000의 농도로 첨가하면 원충을 죽일 수 있어 효과적이다.

지적하신 점에 대해 동감합니다. 일단은 Harrison은 말이 필요없는 Bible이죠...하지만 접해보지 못한 분들도 많을 것 같아서 한번 옮겨와 본 것입니다. 물론 Harrison 책에 정리된 것 보다 훨씬 더 잘 정리된 내용도 많겠지만 Harrison은 공짜로 접할 수 있는 인터넷에 함부로 돌아 다니는 내용이 아니기에 한번 소개를 해 본 것이니 너그럽게 양해해 주시기 바랍니다. 님께서 Trypanosoma cruzi에 대한 의견을 적어주심으로 인해 이곳을 스쳐 지나는 많은 분들이 그리고 감염질환에 대해 접할 기회를 찾지 못한 분들이 하나의 분야를 접할 수 있는 계기를 마련해 주셨다는 생각이 듭니다. 더더우기 우리나라에서는 접하기 어려운 풍토병에 속하는 질병이라 생소하게 여기는 많은 분들이 이런 분야도 있구나 하면서 언젠가 이 분야에 접하게 될 때 이분야를 전공하는 분도 KOSEN에서 만날 수 있겠구나 하는 생각도 들겠죠... 그런점에서 지금껏 KOSEN에서 전혀 언급이 되지 않았던 분야에 대해 눈을 뜨게끔 해 주신데 대해 감사드립니다. 제가 생각하는 이곳은 굉장히 열린 공간이라는 생각을 합니다. 질문하시는 분과 대답하는 분의 두 분만을 위한 공간이 아니라 많은 분들이 이 질문과 대답을 접하면서 간접 경험을 쌓아가고 있다고 생각합니다. 그런데 문제는 인력풀이 크지 않다는 한계를 가지고 있죠...그래서 이 곳에 올라오는 질문에 대해서 정말 그 분야의 전공자가 아님 대가가 나서서 답을 하기란 어려운 것도 사실인것 같습니다. 그러므로 어느 정도 검정된 정보를 공유하는 것도 중요한 일일 것 같습니다. 질문하는 분에게는 직접적인 도움이 되지 못하더라도 이 곳을 이용하시는 또 다른 분들에게는 유용할 수도 있겠지요... 넘 두서없이 적고 있지만 이해해 주시길 바랍니다. 님 때문에 Trypanosoma에 대해 다시 한번 생각이 들게 되어서 기쁘구요 저도 그냥 모른척 지나쳐 버리지 않았다는 점에 대해서 너그럽게 봐 주시길 바랍니다. 차라리 모르른 척 함만 못하다고 말씀하시면 제가 할말은 없겠지요...^^ 아무튼 하시는 일 잘 되시고 좋은 주말 보내시길 바랍니다... Trypanosoma cruzi >님, 님께서 올려 주신것보다 더 나은 인포메이션을 어느 사이트든지 찾을 수 있습니다. 영어보다 한글로도 구할수가 있는데... 저는 직접적으로 알고 있는 정보를 원하였는 것입니다. >이것으로 님께서는 관리를 중요시 하는것이나, 이벤트에 좀 기울어지셨다고 느낍니다. 질문의 노하우에서 적혀 있듯이; 질문하는 당사자의 질문을 찾아 적는것이 정당하고 이렇게 인터넷 사이트의 정보를 수정없이 올린다는것은 완지 어디가 급한듯 보입니다. 제가 님에게 거스르는 말이 아니라 이렇게 하시는게 좋을듯 합니다. >감사합니다. >여기 한 예를 올립니다. 제가 다른 사이트에서 찾은 것이죠. > > >Triatoma infestans and other Triatomines - Biology >The Triatominae are a subfamily of the Reduviidae, or assasin bugs. There are 118 known species (with sizes from 5 mm to 45 mm) and 14 genera. All are obligate bloodsuckers, regardless of age and sex. More than half of them were proven to have the ability to carry Trypanosoma cruzi, the flagellate that causes Chagas disease (Schofield & Dolling 1993 - see the literature list for complete references). Due to their biology and close association with humans, the most important vectors of Chagas disease are Triatoma infestans, Triatoma brasiliensis, Triatoma dimidiata, Triatoma sordita, Rhodnius prolixus, and Panstrongylus megistus (Schofield 1994). > >Host-finding of Triatomine bugs >Triatomine bugs usually leave their refuge during the night to search for their host (Lent & Wygodzinsky 1979; Schofield 1979; Núñez 1987; Schofield & Dolling 1993; Schofield 1994). In dif>ferent experimental setups Triatomine bugs were attracted using potential hosts such as a hamster (Núñez 1982), mice (Taneja & Guerin 1995, Rose & Boeckh 1996b), and humans (Rose & Boeckh 1996a/b). However, the role of individual stimuli such as heat and host odors, including carbon dioxide, is not entirely understood. Rose & Boeckh (1996a) demonstrated that breath is a major stimulus used in the orientation toward the host in Triatoma infestans. The work published so far has been conducted only in the laboratory. > >“The olfactory and thermal senses reside chiefly in the antennae, which serve also to perceive air currents and contact“ (Wiggelsworth & Gillet 1934). Mayer (1968) successfully recorded electrophysiological responses of singele cells in olfactory receptors on the antennae of Triatoma infestans towards breath, Bernard (1974) towards other host odors. > >Warmth >Early findings by Hase (1932) with different species from Venezuela (Panstrongylus geniculatus, Rhodnius pictipes, and Eratyrus cuspidatus) already indicated that warmth is a major reason for the extension of the proboscis. Wiggelsworth & Gillet (1934) confirmed the dominant role of warmth for short distance orientation for Rhodnius prolixus. A warm test tube alone elicited probing. Nicolle & Mathis (1941) also reported probing responses towards warm bodies by Triatoma infestans and Rhodnius prolixus. Over a short distance, a warm current of air was shown to be attractive for already activ>e Triatoma infestans and to elicit probing (Wiesinger, 1956). However, it did not activate resting animals. Núñez (1982) reported that nymphs of Rhodnius prolixus were not activated by warmth. In an olfactometer, they were only slightly attracted, compared to other host odors and carbon dioxide. This was interpreted as an indication that warmth plays only a smaller role in the orientation towards the host over longer distances. Lazzari & Núñez (1989) showed that Triatoma infestans nymphs are able to perceive radiant head and to distinguish between different temperatures of radiant heat sources. > >During his studies of olfactory sensilla of Triatoma infestans, Mayer (1968) did not find any response when he increased or decreased the temperature near the receptor. Lazzari & Wicklein (1994) recorded electrophsysiological activity of the so-called cave-like sense organ in the antennae of Triatoma infestans in response to thermal stimuli. > >Carbon dioxide >The role of carbon dioxide was first investigated by Wiesinger (1956). She concluded that a warm (36 - 40 °C) mixture of carbon dioxide and air is more attractive for T. infestans than warm air alone, both in the activation and orientation responses towards the stimulus source. Núñez (1982) attracted nymphs of Rhodnius prolixus in an olfactometer with carbon dioxide. Rose & Boeckh (1996b) report similar findings for second instar Triatoma infestans. Both Triatoma infestans and Rhodn>ius prolixus also showed oriented responses towards carbon dioxide on a servosphere (Taneja & Guerin 1995). Guerenstein et al. (1995) were able to attract Triatoma infestans using an aerobic cultures of yeast on saccrose. The attraction of these cultures was reduced when the cabon dioxide realesed was partially eliminated using potassium hydroxide. A warm carbon dioxide source was shown to be attractive for nymphs of Triatoma infestans in an enclsure resembling the natural environment of the bugs (Rose & Boeckh 1996a). > >Mayer (1968) reports responses of olfactory sensilla towards carbon dioxide and carbon monoxide. However, these responses were not as strong as those towards breath. > >Other host odors >Other host odors also seem to play a role in host orientation. Wiggelsworth & Gillet (1934) state that during their experiments, some bugs also oriented towards the test tube at room temperature when it was covered with a fresh mouse skin. However, they failed to probe it. No evidence was obtained of either attraction or repulsion by moisture. Núñez (1982) attracted nymphs of Rhodnius prolixus in an olfactometer using his fore arm. Hamster odors were still attractive when they were bubbled through a mixture of potassium hydroxide and water, thus removing both carbon dioxide and lactic acid. Indications that mice give off attractive odors are given by Torres-Estrada & Martínez-Ibarra (1993): They report that starving nymphs of Triatoma gerstaeckeri chos>e mice nests as a hiding-place, whereas fed animals preferred stone walls. Taneja & Guerin (1995) showed oriented responses of nymphs of Rhodnius prolixus and Triatoma infestans on a servosphere towards rabbit urine odors. Rose & Boeckh (1996b) attracted second instar Triatoma infestans using worn socks as a stimulus source. In 1997, Taneja & Guerin reported that ammonia at doses of 3 to 17 ppb attracted Triatoma infestans nymphs on a servosphere. They had detected ammonia both in stale rabbit urine odors as well as in wetted papers with triatomine feces. > >The olfactory sensilla studied by Mayer (1968) also showed responses to some chemicals associated with human breath odors (methanol, methane, furan, pyridine). However, these responses were not as strong as those towards breath. Bernard (1974) also reports electrophsiological responses of sensilla on the antenna of Triatoma infestans towards complex host odors (a finger, sweat), as well as individual chemicals such as lactic acid or butyric acid. Taneja & Guerin (1997) recorded electroantennograms as well as electrophysiological responses of single receptor cells in Triatoma infestans nymphs towards ammonia. > >Triatoma infestans (Klug 1834) > >Size: males 21-26 mm, females 26-29 mm. > >Distribution: From eastern and southern Brazil and the southern half of Bolivia down to the Argentinian province of Chubut. In all of Paraguay and the largest part of Uruguay. East of the Andes in northern Chile and southern Peru. In B>olivia, T. infestans was recorded to reach altitudes of 4100 m. >The species is almost exclusively domestic and peridomestic. Sylvatic colonies are only reported from Bolivia, where they were associated with wild guinea pigs. But usually, the animals are found in human habitations, chicken houses, stables, enclosures or corrals.