Human echinococcosis is a zoonotic larval cestode disease usually caused by Echinococcus granulosus or E. multilocularis. Infection is chronic taking years for symptoms to develop. Because diagnosis and treatment are difficult and reservoirs of infection are maintained in domestic livestock, dogs or wildlife, the disease is difficult to assess in terms of public health and requires long-term control interventions. Estimates of numbers of cystic echinococcosis cases that may occur in 2 large endemic zones, North Africa⁄Middle East and China⁄Central Asia, indicates > 423,000 and > 484,000 cases respectively. Globally, 3.6 million DALYs could be lost due to echinoccocosis. Echinococcosis is therefore a neglected disease which is under-reported and requires urgent attention in common with a number of other zoonoses in order to reduce morbidity and to help alleviate poverty in poor pastoral areas of the sub-tropics and temperate zones
Understanding the transmission ecology of parasites involves the challenge of studying the complexity of life-cycles at multiple levels of biological organisation and at various space-time scales. We think that a single field of science alone cannot fully address this issue and that a way to understand such complexity is to connect various fields of science, to consider the whole transmission system, and to identify which are the variables reasonably accessible to measurement and the relevant scales at which they may provide information about transmission processes and indicate a higher risk of transmission⁄emergence. Based on ongoing studies carried out in Europe and in China, the aim of the present paper is to discuss this approach and to show how results obtained from mass-screening of human populations may be combined to those obtained from small mammal and landscape ecology studies and modelling to promote an understanding of Echinococcus multilocularis transmission and to determine how differences in the time-space scales at which human infection and small mammal population dynamic processes occur may complicate the analysis.
Food-borne zoonotic cestode infections by Diphyllobothrium spp. and Spirometra spp. are relatively uncommon in Indonesia. So far, only one case of diphyllobothriasis was confirmed in 2004 in Jakarta, whereas there were 4 sparganosis cases in Indonesia. Morphology of eggs and gravid proglottids revealed the first case to be caused by Diphyllobothrium species. However, molecular identification of the species was not successful. Sparganosis may not be particularly rare in Indonesia, since Spirometra species have often been found in cats and other animals. These topics in Indonesia are briefly overviewed with reference to historical records and socio-cultural background information.
Cestode zoonosis cases confirmed by PCR-based mitochondrial DNA analysis were investigated. The cestodiosis included taeniasis, cysticercosis, alveolar echinococcosis, cystic echinococcosis, sparganosis mansoni, diphyllobothriasis and diplogonoporiasis. DNA samples were extracted from the ethanol-fixed, formalin-fixed, paraffin-embedded sections, HE-stained, and the PAS- or acetocarmine-stained samples submitted for histopathology. For PCR-based analysis, cytochrome c oxidase subunit 1 and⁄or cytochrome b genes were amplified by multiplex PCR or conventional PCR coupled with DNA sequencing. Although DNA molecules were degraded in most formalin-fixed samples, smaller gene fragments were successfully amplified and the species causing cestodiosis could be identified by DNA sequence analysis of the amplicons. This review describes cestode zoonosis cases in which mitochondrial DNA analysis was useful not only for routine and retrospective diagnosis, but also for genetic polymorphism analysis and molecular identification of the species associated with pathogenicity. The significance of molecular diagnosis using histopathological specimens for cestode zoonoses is also discussed.
Three human taeniid species, Taenia solium, Taenia saginata and Taenia asiatica are distributed in Indonesia. A field survey conducted in Bali from 2002 to 2006 showed that the prevalence of taeniasis was highly variable among four districts (1.1-27.5%), and only two cysticercosis cases due to T. solium infection were detected. All tapeworms (n = 66) expelled from 66 tapeworm carriers were confirmed to be T. saginata by mitochondrial DNA analysis. A total prevalence of 13.0% (19⁄146) for T. solium taeniasis was found in Jayawijaya District, Papua (Irian Jaya). It included 14 of 88 (15.9%) in 1999 and 5 of 58 (8.6%) in 2001, while the seroprevalence of cysticercosis in humans by sub-district in Papua ranged from 0.0% in a non-endemic area to 48.5% in an endemic area from 1996 to 2005. The seroprevalence of cysticercosis in pigs and dogs in Jayawijaya ranged from 8.5% to 70.4% (1998-1999) and 4.9% to 33.3% (2000-2002), respectively. A 2003-2006 survey of 371 local people in Samosir island, north Sumatra revealed 6 of 240 (2.5%) to be infected with T. asiatica; 2 of 58 (3.4%) and 4 of 182 (2.2%) cases were detected in 2003 and 2005, respectively. This brief review summarizes the present situation of taeniasis and cysticercosis, the distribution of three human taeniid species, and the risk factors⁄transmission aspects of these tapeworm infections in Bali, Papua, and north Sumatra regions of Indonesia.
Chagas disease, or American trypanosomiasis, is an arthropod-borne infectious disease, hyperendemic in Latin America, caused by the trypanosome, Trypanosoma cruzi, and transmitted to man by reduviid (or triatomine) bugs. Throughout the Americas, Chagas disease is most commonly transmitted via T. cruzi-infected reduviid bug defecations near bite wounds or exposed mucosal surfaces. Chagas disease may also be transmitted congenitally, by ingestion of T. cruzi-infected reduviids or their feces, by blood product transfusions, and by organ donations. Indeterminate and chronic infections may be re-activated by immunosuppression, particularly HIV⁄AIDS, and by pregnancy. Characterized by an influenza-like illness acutely in adults, Chagas disease may result in heart disease or gastrointestinal megasyndromes following a prolonged or indeterminate stage of subclinical infection. Chagas disease is now among the most common causes of myocarditis in the Americas and the most common cause of death from parasitic diseases in Latin America. Chagas disease will pose increasing communicable disease risks to man and domestic animals throughout the Americas and will be a difficult disease to eradicate due to an army of competent arthropod vectors; a large, nonspecific animal reservoir; a large human reservoir of asymptomatic human infection in the indeterminate stage; limited treatment strategies; and no vaccines.
In vitro drug susceptibility testing of Plasmodium falciparum must be conducted immediately after collecting a sample of the patient‘s blood; otherwise the parasites may weaken and the culture fail. Collecting blood samples from individuals in areas far from the field station or clinic where in vitro testing is conducted requires a reliable method of sample preservation during transportation. We examined and compared three different methods used to preserve blood samples in endemic areas in the Philippines. The three methods are as follows: the on-site method (test is conducted soon after blood sampling), flask culture method (sample is taken to the laboratory in a culture flask with medium) and EDTA tube method (sample is taken to the laboratory in a blood collection tube). The WHO in vitro micro-test for susceptibility of P. falciparum to chloroquine was performed using an AnaeroPack® system and a portable thermostat incubator. Evaluation of the three methods was based on schizont maturation, ease of handling, and risk of contamination during the test. The on-site and flask culture methods, but not the EDTA tube method, were effective for keeping the parasites viable. Furthermore, schizont maturation appeared better with the flask method than with the on-site method, especially in the control wells (drug-free wells). In addition, it was easier to perform the flask method than the on-site method. No contamination was observed using any of the methods. The results of the study suggest that the flask culture method is the most effective and useful way to preserve blood samples for the in vitro test and, moreover, that it aids in providing detailed field evidence of drug-resistant malaria.
In 1999, an insecticide-treated net (ITN) distribution project was started in several malaria-endemic villages in Lao P.D.R., namely Vientiane, Bolikhamxay and Khammouanne Provinces. After the completion of the project, it was found that the ITNs were effective for malaria control based on the analysis of the slide positivity rate for malaria parasites between 1999 and 2000 . We conducted malariometric, entomological and KAP surveys in 2005-06 to confirm the status of malaria and to determine the effectiveness of ITNs in three different socioepidemiological areas (near city, rural and remote), represented by the Xebangfay and Boualapha districts, Khammouanne Province. A marked decrease in the annual malaria incidence and slide positivity rate was noted from 1999 to 2006 in the two districts. The malaria prevalence was significantly reduced in near city areas (5.6%-10.7% in 1999 to 0% in 2005-06) and rural areas (21.4%-50.9% in 1999 to 0%-1% in 2005-06). Twelve positive cases were recorded in remote areas (3.4 - 7.7% in 2006). The illiteracy rate was significantly higher among the respondents in the remote (83.9%) than among those in the near city (32.7%) and rural (54%) areas. In all areas, more than 50% of the villagers indicated that they were not aware of malaria. Similarly, about 60% of the respondents were found to have incorrect knowledge concerning malaria transmission. In remote, 40.9% of the respondents were aware of the methods to prevent malaria infection and 49.5% used mosquito nets throughout the year, rates significantly lower than the corresponding rates in near city and rural. The density of persons per net in remote (3.1-5.9) was considerably higher than that in near city (1.8-2.1) and rural (1.2-2.7). Malaria vector mosquitoes, such as An. minimus and An. nivipes were collected by human-baited adult collection, and cow-baited and CDC light traps. The results of the analysis suggested that the lower the number of persons per net the more effective the reduction of malaria morbidity in these areas. It is imperative that ITN distribution and health education regarding malaria be strengthened, especially in remote, but also in other areas.
Small bowel ileus due to the parasitic infection caused by omophagia of freshwater fish is relatively rare. We present a case of small bowel ileus possibly caused by inflammatory change associated with Gnathostoma doloresi infection. A 62-year-old man underwent partial resection of the small bowel under a diagnosis of ileus due to complete obstruction of the small bowel. He had eaten a few slices of raw freshwater fish four weeks before abdominal pain appeared, and he contracted creeping disease with several welts on the abdominal wall. Chronic inflammatory change suggestive of parasite infection was observed in the resected specimen. An immunoserodiagnostic study using microenzyme-linked immunosorbent assay led to a diagnosis of Gnathostoma doloresi infection. The postoperative course was favorable, and the patient was discharged 12 days after surgery. Only two cases of ileus due to Gnathostoma doloresi infection have ever been reported.