Susan P. Montgomery

An Estimate of the Burden of Chagas Disease in the United States

Chagas disease causes the highest burden of any parasitic disease in the Western hemisphere. By applying published seroprevalence figures to immigrant populations, we estimate that 300,167 individuals with Trypanosoma cruzi infection live in the United States, with 30,000-45,000 cardiomyopathy cases and 63-315 congenital infections annually. T. cruzi causes a substantial disease burden in the United States.

The epidemic of West Nile virus in the United States, 2002.

Since 1999, health officials have documented the spread of West Nile virus across the eastern and southern states and into the central United States. In 2002, a large, multi-state, epidemic of neuroinvasive West Nile illness occurred. Using standardized guidelines, health departments conducted surveillance for West Nile virus illness in humans, and West Nile virus infection and illness in non-human species. Illnesses were reported to the Centers for Disease Control and Prevention (CDC) through the ArboNET system. In 2002, 39 states and the District of Columbia reported 4,156 human West Nile virus illness cases. Of these, 2,942 (71%) were neuroinvasive illnesses (i.e., meningitis, encephalitis, or meningoencephalitis) with onset dates from May 19 through December 14; 1,157 (28%) were uncomplicated West Nile fever cases, and 47 (1%) were clinically unspecified. Over 80% of neuroinvasive illnesses occurred in the central United States. Among meningitis cases, median age was 46 years (range, 3 months to 91 years), and the fatality-to-case ratio was 2%; for encephalitis cases (with or without meningitis), median age was 64 years (range, 1 month to 99 years) and the fatality-to-case ratio was 12%. Neuroinvasive illness incidence and mortality, respectively, were significantly associated with advanced age (p = 0.02; p = 0.01) and being male (p < 0.001; p = 0.002). In 89% of counties reporting neuroinvasive human illnesses, West Nile virus infections were first noted in non-human species, but no human illnesses were reported from 77% of counties in which non-human infections were detected. In 2002, West Nile virus caused the largest recognized epidemic of neuroinvasive arboviral illness in the Western Hemisphere and the largest epidemic of neuroinvasive West Nile virus ever recorded. It is unknown why males appeared to have higher risk of severe illness and death, but possibilities include higher prevalence of co-morbid conditions or behavioral factors leading to increased infection rates. Several observations, including major, multi-state West Nile virus epidemics in 2002 and 2003, suggest that major epidemics may annually reoccur in the United States. Non-human surveillance can warn of early West Nile virus activity and needs continued emphasis, along with control of Culex mosquitoes.

Epidemiologic and zoonotic aspects of ascarid infections in dogs and cats.

Toxocaracanis and Toxocara cati of dogs and cats, respectively, can cause significant disease in people. Human seroprevalence for Toxocara antibodies varies with factors such as geographic location, socio-economic status, and dietary habits. Risk factors for infection include geophagia and low-level education. Toxocara canis is better recognized as a cause of human toxocariasis, but Toxocara cati should not be overlooked. In addition, patent infections with Baylisascaris procyonis, the raccoon ascarid, have been increasingly recognized in dogs. Pet owners need to be properly educated about zoonotic risks, and veterinarians should institute regular parasite screening and treatment for all pets. Establishment of national surveillance programs to determine the incidence and specific etiological agent in human larva migrans patients would aid in the development of targeted intervention strategies.

Hookworms of dogs and cats as agents of cutaneous larva migrans

Dogs and cats are hosts to hookworms that may cause zoonotic disease, most notably, cutaneous larva migrans. Ancylostoma braziliense is most often implicated in dermatological lesions, and Ancylostoma caninum has been associated with eosinophilic enteritis and suggested as a possible cause of diffuse unilateral subacute neuroretinitis in humans. Other manifestations include eosinophilic pneumonitis, localized myositis, folliculitis, erythema multiforme, or ophthalmological manifestations. Ancylostoma eggs are morphologically indistinguishable, which complicates epidemiological studies. Surveys of dermatologists, gastroenterologists, and ophthalmologists would help to define the incidence of these zoonotic infections. Improved diagnostic tests are needed to identify the causative species involved and understand the epidemiology of hookworm disease. This review describes the discovery of the disease, the biology of the agents, and how that biology may impact disease.

Chagas disease and the US blood supply.

Purpose of review To describe new developments in blood-bank screening and management of patients with chronic Trypanosoma cruzi infection in the United States. Recent findings The first US Food and Drug Administration licensed serological test for T. cruzi blood screening went into widespread usage in January 2007. More than 500 confirmed T. cruzi-infected donations were detected by mid-June 2008. Until recently, drug therapy was recommended for acute and congenital infections, but seldom for chronic infections, which were believed to respond poorly. However, in the 1990s, efficacy was demonstrated in two placebo-controlled trials of benznidazole in children with chronic T. cruzi infection. In 2006, a nonrandomized, nonblinded trial demonstrated that benznidazole treatment may slow progression of cardiomyopathy and decrease mortality risk in infected adults. Summary Blood-bank screening will continue to detect T. cruzi-infected donors. Based on recent data, antitrypanosomal treatment is recommended for all acute and congenital T. cruzi infections, reactivated infection, and chronically infected children. In adults aged 19–50 years without advanced heart disease, treatment should generally be offered; management should be individualized for older adults. Less toxic, more effective drugs, a sensitive, specific assay for response to treatment, and improved healthcare access would promote more effective management.

Evaluation of urine CCA assays for detection of Schistosoma mansoni infection in Western Kenya.

Although accurate assessment of the prevalence of Schistosoma mansoni is important for the design and evaluation of control programs, the most widely used tools for diagnosis are limited by suboptimal sensitivity, slow turn-around-time, or inability to distinguish current from former infections. Recently, two tests that detect circulating cathodic antigen (CCA) in urine of patients with schistosomiasis became commercially available. As part of a larger study on schistosomiasis prevalence in young children, we evaluated the performance and diagnostic accuracy of these tests—the carbon test strip designed for use in the laboratory and the cassette format test intended for field use. In comparison to 6 Kato-Katz exams, the carbon and cassette CCA tests had sensitivities of 88.4% and 94.2% and specificities of 70.9% and 59.4%, respectively. However, because of the known limitations of the Kato-Katz assay, we also utilized latent class analysis (LCA) incorporating the CCA, Kato-Katz, and schistosome-specific antibody results to determine their sensitivities and specificities. The laboratory-based CCA test had a sensitivity of 91.7% and a specificity of 89.4% by LCA while the cassette test had a sensitivity of 96.3% and a specificity of 74.7%. The intensity of the reaction in both urine CCA tests reflected stool egg burden and their performance was not affected by the presence of soil transmitted helminth infections. Our results suggest that urine-based assays for CCA may be valuable in screening for S. mansoni infections.

The United States Trypanosoma cruzi Infection Study: evidence for vector-borne transmission of the parasite that causes Chagas disease among United States blood donors.

BACKGROUND: Screening US blood donors for Trypanosoma cruzi infection is identifying autochthonous, chronic infections. Two donors in Mississippi were identified through screening and investigated as probable domestically acquired vector‐borne infections, and the US T. cruzi Infection Study was conducted to evaluate the burden of and describe putative risk factors for vector‐borne infection in the United States.

Screening and Treatment of Chagas Disease in Organ Transplant Recipients in the United States: Recommendations from the Chagas in Transplant Working Group

Donor‐derived transmission of Trypanosoma cruzi, the etiologic agent of Chagas disease, has emerged as an issue in the United States over the past 10 years. Acute T. cruzi infection causes substantial morbidity and mortality in the posttransplant setting if not recognized and treated early. We assembled a working group of transplant infectious disease specialists, laboratory medicine specialists, organ procurement organization representatives and epidemiologists with expertise in Chagas disease. Based on review of published and unpublished data, the working group prepared evidence‐based recommendations for donor screening, and follow‐up testing and treatment of recipients of organs from infected donors. We advise targeted T. cruzi screening of potential donors born in Mexico, Central America and South America. Programs can consider transplantation of kidneys and livers from T. cruzi‐infected donors with informed consent from recipients. However, we recommend against heart transplantation from infected donors. For other organs, we recommend caution based on the anticipated degree of immunosuppression. Our recommendations stress the need for systematic monitoring of recipients by polymerase chain reaction, and microscopy of buffy coat and advance planning for immediate antitrypanosomal treatment if recipient infection is detected. Data on management and outcomes of all cases should be collected to inform future guidelines and to assist in coordination with public health authorities.

Chagas Disease Has Now Gone Global

Chagas disease, caused by the parasite Trypanosoma cruzi, was once thought to be an exotic disease, confined to endemic areas of Latin America and hence of little importance to anyone outside of these endemic regions, including most physicians and scientists. The impact of the lack of physician awareness and lack of scientific attention is undefined, but may contribute to the continued neglect of Chagas disease and the affected populations. Despite historical evidence and growing recognition of the spread of Chagas disease, the prevention and control of this disease outside of Latin America is only now being addressed.

Transfusion‐associated transmission of West Nile virus, United States 2003 through 2005

BACKGROUND: National blood donation screening for West Nile virus (WNV) started in June 2003, after the documentation of WNV transfusion‐associated transmission (TAT) in 2002.