Parasitic infections in travelers and immigrants: part I protozoa.

The growth in international commerce, travel and migration contribute to the global emergence of certain parasitic infections. Importation of vectors and food products may contribute to the emergence of protozoan infections in nonendemic countries. Infections such as malaria are potentially fatal, especially in nonimmune patients, and outcome depends largely on timely diagnosis and treatment. Diagnosis/management of imported parasitic infections may be complex especially as some patients may have underlying immunosuppressive conditions such as HIV infection. Major challenges concern the development of improved diagnostic techniques, safer/more effective drug therapies and identification of biological markers of progression and response to treatment. Imported parasitic diseases which may be transmitted vertically or through blood transfusion/organ donation could become a public health priority in the near future. Climate change may affect arthropod distribution and facilitate the spread of protozoan vector-borne diseases. The first part of this review focuses on protozoan infections in travelers and immigrants.

Differences in prevalence of geohelminth infections between indigenous and settler populations in a remote Amazonian region of Peru.

OBJECTIVE: To compare prevalences of intestinal helminths and waterborne protozoa in indigenous and settler populations in a remote area of Peru. These populations live in adjacent but segregated small urban villages. METHODS: Stool samples were collected from representative members of these two populations and analysed for geohelminths and protozoa. RESULTS: The risk of soil-transmitted helminths is significantly higher in the settler than the indigenous population in the same isolated region of Peru (OR 5.18; 95% CI 3.44-7.81; P < 0.001). In contrast, the rates of protozoa presence were similar in both populations (OR 1.28; 95% CI 0.77-2.14; P = 0.336). CONCLUSIONS: Potential explanations for unexpected finding of a lower prevalence of helminths in indigenous relative to the settler population could include housing design in flood - prone areas and the use of local medicinal plants that possibly have antihelmintic properties.

Intestinal parasitism prevalence amongst children from six indigenous communities residing in Cali, Colombia.

OBJECTIVE: Establishing the prevalence of intestinal parasitism in children aged 5 to 14 years of age from six indigenous communities residing in the city of Cali. METHODOLOGY: A cross-sectional, descriptive epidemiological study was carried out in six indigenous communities residing in the city of Cali; it consisted of making a direct serial and concentration coproparasitological examination of a randomly selected sample of fifty-seven 5 to 14 year-old children. RESULTS: Of the 57 samples obtained, 84 % of the children were infected with parasites; protozoa (98 %) predominated over helminths (16.7 %) and mixed parasitemia was found in 14.6 % of the samples. Monoparasitism appeared in children over 10 years of age and biparasitism (10.4 %) and polyparasitism (52.1 %) in children under 10 years of age. Regarding occult blood determination, 6 % were observed to be positive in all the samples analysed; 4 % of these results were associated with E. histolyticaldispar. The simple parasitism index (SPI) reflected a high degree of infestation amongst the children included in the study. CONCLUSIONS: The prevalence of intestinal parasitism in indigenous infants was higher than that reported nationally in the overall adolescent and school-aged children population in the same age group. Mono- and polyparasitism prevailed in the positive samples. The infestation load was not randomly distributed amongst the communities.

Intestinal parasitism prevalence amongst children from six indigenous communities residing in Cali, Colombia / Prevalencia de parasitismo intestinal en menores de seis comunidades indígenas residentes en Cali, Colombia

Objective Establishing the prevalence of intestinal parasitism in children aged 5 to 14 years of age from six indigenous communities residing in the city of Cali. Methodology A cross-sectional, descriptive epidemiological study was carried out in six indigenous communities residing in the city of Cali; it consisted of making a direct serial and concentration coproparasitological examination of a randomly selected sample of fifty-seven 5 to 14 year-old children. Results Of the 57 samples obtained, 84 % of the children were infected with parasites; protozoa (98 %) predominated over helminths (16.7 %) and mixed parasitemia was found in 14.6 % of the samples. Monoparasitism appeared in children over 10 years of age and biparasitism (10.4 %) and polyparasitism (52.1 %) in children under 10 years of age. Regarding occult blood determination, 6 % were observed to be positive in all the samples analysed; 4 % of these results were associated with E. histolyticaldispar. The simple parasitism index (SPI) reflected a high degree of infestation amongst the children included in the study. Conclusions The prevalence of intestinal parasitism in indigenous infants was higher than that reported nationally in the overall adolescent and school-aged children population in the same age group. Mono- and polyparasitism prevailed in the positive samples. The infestation load was not randomly distributed amongst the communities.

Objetivo Establecer la prevalencia de parasitismo intestinal en menores de 5 a 14 años de seis comunidades indígenas residentes en la ciudad de Cali. Metodología Se llevó a cabo un estudio epidemiológico transversal en seis comunidades indígenas residentes en la ciudad de Cali, que consistió en realizar un examen seriado coproparasitológico a una muestra de menores entre 5 y 14 años elegida al azar. Resultados De las 57 muestras, un total de 84 % estaban infectados con parásitos; en los cuales predominaron los protozoarios (98 %) sobre los helmintos (16,7 %) y la presencia de enfermedades parasitarias intestinales mixtas fue del 14,6 %. El monoparasitismo se observe en los mayores de 10 años; en niños por debajo de los 10 años se observó el biparasitismo (10,4 %) y poliparasitismo (52,1 %). Con relación a la determinación de sangre oculta, un 6 % de las muestras fueron positivas, 4 % de esos resultados estaban asociados con E. histolyticaldispar. El índice de parasitismo simple refleja un alto grado de infestación en los menores incluidos en este estudio. Conclusiones La prevalencia de parasitismo intestinal en menores de ascendencia indígena es mayor a la reportada en el orden nacional en menores escolares y adolescentes. Sobresalieron el mono y poliparasitismo en las muestras positivas. La carga de infestación no se distribuyó al azar entre las comunidades.

Intestinal parasitic infections amongst Orang Asli (indigenous) in Malaysia: has socioeconomic development alleviated the problem?

Orang Asli are the indigenous minority peoples of peninsular Malaysia. Despite proactive socioeconomic development initiated by the Malaysian Government in upgrading the quality of life of the Orang Asli communities since 1978, they still remained poor with a current poverty rate of 76.9%. Poverty exacerbates the health problems faced by these communities which include malnourishment, high incidences of infectious diseases (eg. tuberculosis, leprosy, malaria) and the perpetual problem with intestinal parasitic infections. Studies reported that the mean infection rate of intestinal parasitic infections in Orang Asli communities has reduced from 91.1% in 1978, to 64.1% in the subsequent years. Although the results was encouraging, it has to be interpreted with caution because nearly 80% of studies carried out after 1978 still reported high prevalence (i.e. >50%) of soil-transmitted helminthiases (STH) among Orang Asli communities. Prior to 1978, hookworm infection is the most predominant STH but today, trichuriasis is the most common STH infections. The risk factors for intestinal parasitic infections remained unchanged and studies conducted in recent years suggested that severe STH infections contributed to malnutrition, iron deficiency anaemia and low serum retinol in Orang Asli communities. In addition, STH may also contribute to poor cognitive functions and learning ability. Improvements in socioeconomic status in Malaysia have shown positive impact on the reduction of intestinal parasitic infections in other communities however, this positive impact is less significant in the Orang Asli communities. In view of this, a national parasitic infections baseline data on morbidity and mortality in the 18 subgroups of Orang Asli, will assist in identifying intervention programmes required by these communities. It is hope that the adoption of strategies highlighted in the World Health Organisation- Healthy Village Initiatives (WHO-HVI) into Orang Asli communities will ensure the whole mechanism of delivery and empowerment by the government agencies become more efficient and productive in alleviating intestinal parasitic infections in these communities.

Intestinal protozoa and intestinal helminthic infections in displacement camps in Sierra Leone.

Displacement and refugee camps provide ideal grounds for the transmission of parasites and increase the risk of acute respiratory infections, diarhoea diseases, and intestinal parasitic infection. Cryptosporidium parvum, Giardia lamblia, Entomoeba histolytica, Ascaris lumbricoides, hookworm infection, Schistosoma haematobium, S. mansoni and Strongyloides stercoralis are important cosmopolitan intestinal parasites that are common among children, the immunocompromised and displaced populations. Five hundred and eighty one residents from 5 Internally Displaced Persons (IDPs) Camps voluntarily participated in the study by providing stool and urine samples for analysis. The stool specimens were used for the detection of Cryptosporidium specific and Giardia specific antigens by the DMSO modified Acid-Fast and Trichrome-PLUS stain for C. parvum and G. lamblia and E. histoyltica respectively. Stool specimens for the demonstration of helminth eggs and larvae were prepared by the modified Kato technique. One hundred and seventy eight (31%) of the 581 camp residents that submited samples were children below 10 years of age and were selected because they were screened for various forms of malnutrition. However, the data on C. parvum and G. lamblia were included in the analysis for all parasites. More children were positive for G. lamblia (29%) than for C. parvum (10%) and 5% had double infection with both parasites. The antigen positive rate decreased with age for C. parvum and G. lamblia infections. Adult samples were also examined for the C. parvum, G. lamblia, E. histolytica, A. lumbricoides, hookworms, S. haematobium, S. mansoni and S. stercoralis. The prevalence of hookworm was highest at Parade Ground Camp (50%) and hookworm had the highest pevalence rate of 18% among the 581 IDP residents followed by S. mansoni (16.7%) and A. lumbricoides (15%). The overall prevalence of E. histolytica among the study population was 9.0%. The results of this study indicate that intestinal protozoan and helminth parasites are highly prevalent among camp residents in Sierra Leone with five (5) different helminth parasites demonstrated in the stool specimens of residents in the five IDP camps.

[Prevalence of intestinal parasites in children of Yukpa Ethnia in Toromo, Zulia State, Venezuela]. / Prevalencia de enteroparásitos en niños de la etnia Yukpa de Toromo, Estado Zulia, Venezuela.

BACKGROUND: Yupkpa community in Perijá Sierra does not have drinking water or sewage elimination systems. Thus it becomes a propitious place for infection with intestinal parasites. AIM: To determine the prevalence of intestinal parasites in children, ages 0 to 14 years, in the Yukpa ethnic population of Toromo in the Perijá Mountains, Zulia State, Venezuela. MATERIAL AND METHODS: Ninety one fecal samples were analyzed by the following coproparasitologic methods: saline solution and lugol fresh mount, formalin-ether concentration (Ritchie), and Kinyoun stain for intestinal coccidians. RESULTS: Overall parasite infection prevalence was 83.5%. The most frequently observed parasites were: Ascaris lumbricoides (57.1%), Trichuris trichiura (20.8%), Hymenolepis nana (14.2%), Blastocystis hominis (51.6%), Giardia lamblia (30.7%), and Entamoeba histolytica/E. dispar complex (21.9%). Coccidians were nont observed in any of the stool samples. CONCLUSIONS: The large number of infected people is directly related to the hygienic and sanitary conditions of the population studied.

Prevalencia de enteroparásitos en niños de la etnia Yukpa de Toromo, Estado Zulia, Venezuela / Prevalence of Intestinal Parasites in Children of Yukpa Ethnia in Toromo, Zulia State, Venezuela

Background: Yupkpa community in Perijá Sierra does not have drinking water or sewage elimination systems. Thus it becomes a propitious place for infection with intestinal parasites. Aim: To determine the prevalence of intestinal parasites in children, ages 0 to 14 years, in the Yukpa ethnic population of Toromo in the Perijá Mountains, Zulia State, Venezuela. Material and Methods: Ninety one fecal samples were analyzed by the following coproparasitologic methods: saline solution and lugol fresh mount, formalin-ether concentration (Ritchie), and Kinyoun stain for intestinal coccidians. Results: Overall parasite infection prevalence was 83.5%. The most frequently observed parasites were: Ascaris lumbricoides (57.1%), Trichuris trichiura (20.8%), Hymenolepis nana (14.2%), Blastocystis hominis (51.6%), Giardia lamblia (30.7%), and Entamoeba histolytica/E. dispar complex (21.9%). Coccidians were nont observed in any of the stool samples. Conclusions: The large number of infected people is directly related to the hygienic and sanitary conditions of the population studied.

Parásitos intestinales en una comunidad Amerindia, Costa Rica / Intestinal parasites in an Amerindian community

In Costa Rica there were three national surveys of intestinal parasitism (1966, 1982, and 1996) that showed dramatic reduction of the prevalence of Trichuris, Ascaris, and Necator/Ancylostoma (hookworms); however, these nematodes persist with high prevalence in low socio-economically groups, as the squatter settlements around the cities; however, it is possible that pour Amerindian communities with substandard housing condition also suffer the burden of intestinal parasites. For this reason, the present study was planted in a rural disperse Amerindian community from the South of Costa Rica. 45 fecal samples were collected from children under 15 years old, and were processed according a modification of the Baermann method, which also permits the observation of other parasites beyond Strongyloides. 38 (84 percent) of the analyzed samples were positive for at least one parasite. The prevalence for nematodes was Ascaris (36 percent), hookworms (22 percent) Enterobius (4 percent), and Trichuris (2 percent). For protozoa was Endolimax nana (33 percent), Entamoeba coli (27 percent), and Entamoeba histolytica/dispar (11 percent). These data are the reflect of the inadequate sanitation conditions of this community.

In Costa Rica there were three national surveys of intestinal parasitism (1966, 1982, and 1996) that showed dramatic reduction of the prevalence of Trichuris, Ascaris, and Necator/Ancylostoma (hookworms); however, these nematodes persist with high prevalence in low socio-economically groups, as the squatter settlements around the cities; however, it is possible that pour Amerindian communities with substandard housing condition also suffer the burden of intestinal parasites. For this reason, the present study was planted in a rural disperse Amerindian community from the South of Costa Rica. 45 fecal samples were collected from children under 15 years old, and were processed according a modification of the Baermann method, which also permits the observation of other parasites beyond Strongyloides. 38 (84%) of the analyzed samples were positive for at least one parasite. The prevalence for nematodes was Ascaris (36%), hookworms (22%) Enterobius (4%), and Trichuris (2%). For protozoa was Endolimax nana (33%), Entamoeba coli (27%), and Entamoeba histolytica/dispar (11%). These data are the reflect of the inadequate sanitation conditions of this community.

European strategies against the parasite transfusion risk.

Protozoal infections are endemic in mainly tropical low income countries, affecting millions of people. Malaria, American trypanosomiasis (Trypanosoma cruzi/Chagas disease) and protozoal tickborne diseases (e.g. Babesia) can be efficiently transmitted by transfusion of cellular blood components. In non-endemic areas like Europe malaria, Chagas disease and Babesia are imported diseases resulting of travelling to endemic areas and migration of autochthons from these endemic areas. A recent International Forum showed that in Europe, as well as the USA, prevention of transfusion-associated protozoal infections depend mainly on selection of donors using questionnaires. Most countries divide donors at risk for malaria in two groups: individuals who have lived in the first 5 years of their life in malaria endemic areas and those who are borne and residing in non-endemic areas and visited the endemic area(s). The first category of donors is rejected for 3 years after their last visit to the endemic area, and in one country such donors are permanently rejected. In some countries such donors are accepted after 4 months-3 years, provided a test for malaria is non-reactive. Persons from non-endemic areas, who visited the malaria endemic area, are rejected for 4-12 months. Some countries reject these donors for 3 years or permanently when they resided for more than 6 months in the endemic area. The rejection rate of donors for malaria risk in the various countries was 0.003-0.43% of all donations. Over the last decade only a few cases of TT-malaria were reported in the various countries. In several countries donors are questioned for risk of T. cruzi infection. In some countries donors are excluded when they (or their mothers) were born in South or Central America, if they received a blood transfusion in these areas and if they lived in rural areas in these endemic countries for more than 4 weeks. In none of the countries donors are asked if they had Babesia or Leishmania. At present implemented measures to prevent TT-malaria in the European countries are probably highly effective. More research is needed to establish the theoretical risk of TT-T. cruzi and TT-Leishmania infection in Europe, before preventive measures may be considered.

Prevalence of intestinal parasitic infestation in schoolchildren in the northeastern part of Kathmandu Valley, Nepal.

This paper presents the status of intestinal parasitosis in public schoolchildren (1 to 10 classes) in a rural area of the Kathmandu Valley, Nepal. A total of 533 schoolchildren (269 girls and 264 boys, aged 4 to 19 years) were included in this study. A questionnaire was filled out regarding hygienic and other habits, including factors predisposing to parasitic infections. Fecal samples from the children were examined by formol-ether concentration technique. The overall prevalence of parasitosis was 66.6% (395/533) with no significant difference between boys and girls (p> 0.05). Tibeto-Burman children had a non-significant higher prevalence, compared with Indo-Aryan and Dalit children (p>0.05). Half (53.8%; 191/355) of the children had multiple parasitic infections. Altogether, nine types of parasites were recovered. The recovery rate of helminths was higher (76.9%) than protozoa (23.1%). Trichuris trichiura was the most common helminth detected, followed by hookworm, Ascaris lumbricoides and others. Entamoeba coli was the most common protozoan parasite, followed by E. histolytica, Giardia lamblia and others.

Survey for intestinal parasites in Belize, Central America.

A stool survey was carried out in 5 villages in the Toledo district of the Central American country of Belize. Eighty-two percent of a total population of 672 participated. The stools were examined by the formalin-ethyl-acetate concentration technique. Sixty-six percent of the population was found to have one or more intestinal parasites. The most common infection was hookworm (55%) followed by Ascaris lumbricoides (30%), Entamoeba coli (21%), Trichuris trichiura (19%), Giardia lamblia (12%), Iodamoeba beutschlii (9%), and Entamoeba histolytica/dispar (6%). Other parasites found were Entamoeba hartmani, Strongyloides stercoralis, Endolimax nana, Isospora belli, and Chilomastix mesnili. Children were more often infected than adults and more females had hookworm infections. Sixty percent of 111 households surveyed had dirt floors, 43% were without toilets, 35% of the houses were overcrowded, and 10% obtained drinking water from streams. Cross-tabulation and logistic regression analyses were used to identify risk and protective factors associated with parasitoses. The risk factors were: being in the Mayan Ketchi population group, and abtaining housework and drinking water from streams. Protective factors were: drinking treated water and the wearing of shoes.

Changing patterns in intestinal parasitic infections among Southeast Asian laborers in Taiwan.

In order to determine whether there are changing patterns in intestinal parasitic infections among foreign laborers in North Taiwan, one fecal specimen was obtained from each of 1,569 laborers and examined by the formalin-ethyl acetate sedimentation technique. The prevalence of intestinal parasitic infections was 8.2%. Females (11.7%) had a significantly higher prevalence than males (6.9%), although there was no significant difference between Filipinos (7.7%), Thais (8.3%) and Indonesians (12.5%). Blastocystis hominis (3.4%) had the highest prevalence among the nine species of parasites detected. The significantly higher prevalence of B. hominis in the entry examination indicates an increasing trend in incoming Southeast Asian laborers. In addition, the prevalence of soil-transmitted helminth infections has become extremely low. Female laborers had a significantly higher positive rate. Although Opisthorchis viverrini/Clonorchis sinensis remains prevalent among Thais, the positive rate was also significantly reduced. These epidemiological patterns are different from those observed in previous studies and may be attributed to the long-term and constant movement of the foreign laborers.

Targeted chemotherapy for parasite infestations in rural black preschool children.

OBJECTIVE: To investigate whether targeted chemotherapy can reduce parasite prevalence rates in rural black preschool children. DESIGN: The study consisted of a before/after trial. Stool and urine samples were analysed on four occasions over a 21-week period. SETTING: Crèches in two rural areas of southern KwaZulu/Natal (coastal and inland). PATIENTS: Two hundred children of 4-6 years of age attending 19 crèches in the area. INTERVENTION: Targeted chemotherapy using albendazole for nematode infestations, praziquantel for trematode and cestode infestations and metronidazole for protozoal infections was administered twice at an interval of 14 weeks. MAIN OUTCOME MEASURE: Prevalence rates. RESULTS: The prevalence of Ascaris lumbricoides, Trichuris trichiura and Necator americanus infestation decreased significantly after treatment. Reinfestation rates 12 weeks after treatment were 16% for A. lumbricoides, 33% for T. trichiura, 24% for Giardia lamblia and 3% for N. americanus. No reinfestation was noted for Schistosoma haematobium, Hymenolepsis or Taenia species. CONCLUSION: The study suggests that parasite prevalence rates in children can be reduced by the administration of appropriate chemotherapy at regular intervals. However, the provision of clean water and adequate sewerage facilities remains a high priority for black communities living in rural areas of South Africa.

Intestinal parasitic infection in operation Solomon immigrants.

Previous studies have documented a high infection rate of intestinal parasites in Ethiopian immigrants to Israel. As a result, current treatment recommendations are for mass treatment without prior screening tests. However, the group of 15,400 Ethiopian immigrants who arrived in Israel in May 1991 (Operation Solomon) represents a somewhat different population from those who had immigrated earlier. The 1991 immigrants had spent 9-12 months in Addis Ababa before their evacuation; the conditions there, together with the provision of medical care, may have resulted in lower infection rates for intestinal parasites. The purpose of this study was to determine the prevalence of intestinal parasites in these recent immigrants to assess whether mass treatment would still be appropriate. Random stool specimens were obtained from 80 residents of a population of 650 Ethiopian immigrants who were cared for at a Jerusalem clinic. Specimens were examined at the Ministry of Health Laboratory. Of the 80 specimens 45 had sufficient quantity of stool to perform the standard Richie concentration method. Pooling results from all 80 individuals revealed 60 (75.0%) positive specimens, 53 (66.3%) with at least one pathogenic parasite, and 21 (26.3%) with multiple pathogenic parasites. These data provide the first systematic information on intestinal parasitosis in immigrants from Operation Solomon and suggest that mass treatment in this group is appropriate.

Intestinal protozoan infections in Malaysia.

Intestinal protozoa are found in all communities in Malaysia and among all ethnic groups. Prevalence of intestinal protozoa is not affected by ethnicity but by living conditions. Communities with both basic amenities of safe water supply and proper toilets have lower prevalence than those with one or none of the amenity. Cryptosporidium is an important intestinal protozoon in Malaysia and should be included in future field and laboratory studies and also in laboratory diagnosis for pathogens. Much interest will be centered on Blastocystis hominis in future studies in view that it may be a cause of diarrhea.