Molecular Detection of Ancylostoma duodenale, Ancylostoma ceylanicum, and Necator americanus in Humans in Northeastern and Southern Thailand

The 2 principal species of hookworms infecting humans are Necator americanus and Ancylostoma duodenale. Case studies on zoonotic hookworm infections with Ancylostoma ceylanicum and/or Ancylostoma caninum are known mainly from Asian countries. Of these 2 zoonotic species, only A. ceylanicum can develop to adulthood in humans. In the present study, we report a molecular-based survey of human hookworm infections present in southern and northeastern Thailand. Thirty larval hookworm samples were obtained from fecal agar plate cultures of 10 patients in northeastren Thailand and 20 in southern Thailand. Partial ITS1, 5.8S, and ITS2 regions of the ribosomal DNA genes were amplified using PCR. The amplicons were sequenced, aligned, and compared with other hookworm sequences in GenBank database. The results showed that, in Thailand, N. americanus is more prevalent than Ancylostoma spp. and is found in both study areas. Sporadic cases of A. ceylanicum and A. duodenale infection were seen in northeastern Thailand.

Application of a real-time PCR method for detecting and monitoring hookworm Necator americanus infections in Southern China

<p><b>OBJECTIVE</b>To develop a quantitative PCR method for detecting hookworm infection and quantification.</p><p><b>METHODS</b>A real-time PCR method was designed based on the intergenic region II of ribosomal DNA of the hookworm Necator americanus. The detection limit of this method was compared with the microscopy-based Kato-Katz method. The real-time PCR method was used to conduct an epidemiological survey of hookworm infection in southern Fujian Province of China.</p><p><b>RESULTS</b>The real-time PCR method was specific for detecting Necator americanus infection, and was more sensitive than conventional PCR or microscopy-based method. A preliminary survey for hookworm infection in villages of Fujian Province confirmed the high prevalence of hookworm infections in the resident populations. In addition, the infection rate in women was significantly higher than that of in men.</p><p><b>CONCLUSIONS</b>A real-time PCR method is designed, which has increased detection sensitivity for more accurate epidemiological studies of hookworm infections, especially when intensity of the infection needs to be considered.</p>

A Case of Severe Anemia by Necator americanus Infection in Korea

This report describes clinical and parasitological findings of an 82-yr-old female patient who lived in a local rural village and suffered from severe chronic anemia for several years. She was transferred to the National Police Hospital in Seoul for management of severe dyspnea and dizziness. At admission, she showed symptoms or signs of severe anemia. Gastroduodenoscopy observed hyperemic mucosa of the duodenum and discovered numerous moving roundworms on the mucosa. Endoscopy isolated seven of them, which were identified as Necator americanus by characteristic morphology of cutting plates in the buccal cavity. The patient was treated with albendazole and supportive measures for anemia, and her physical condition much improved. This case suggests the possibility that hookworm N. americanus is still transmitted in a remote local mountainous area in Korea.

A study on the prevalence of hookworm infection in four districts of West Bengal and its linkage with anaemia.

Stool samples collected from the districts of Darjeeling, Jalpaiguri, Hooghly and Calcutta in West Bengal were examined for hookworm and associated parasites. It was found that maximum prevalence of hookworm was in Hooghly district (24.8%). N. americanus appeared to be more prevalent species in all the districts studied. The load ofhookworm infection appeared to be mostly in the mild range. Ascaris lumbricoides appeared to the most common accompanying infection. In the affected population, the degree of anaemia was mostly mild.

Protective immunity elicited by ultraviolet-irradiated third-stage infective hookworm (Necator americanus and Ancylostoma caninum) larvae in mice and hamsters.

The protective immunity elicited by ultraviolet-irradiated third-stage infective larvae of Necator americanus (UV-NaL3) and Ancylostoma caninum (UV-AcL3) was evaluated in laboratory mice (a non-permissive model) and hamsters (a permissive model). After optimizing the time of exposure to UV-irradiation, both oral and subcutaneous vaccination routes with UV-AcL3 in mice were explored. Oral vaccination was more effective at reducing the number of challenge AcL3 entering the lungs, whereas subcutaneous vaccination was more effective at blocking muscle entry. When UV-irradiated NaL3 and non-irradiated AcL3 were used as vaccines in hamsters, both of them were effective at reducing adult hookworm burdens. However, the length of protection afforded by UV-irradiated L3 was substantially greater than that resulting from immunization with non-irradiated L3. A single dose was less effective than multiple doses. The protective immunity elicited by UV-irradiated NaL3 given once every other week for a total of three immunizations was similar to that elicited by non-irradiated AcL3 given during the same schedule. Protection was not significantly affected by administering the L3 on a weekly basis for a total of three immunizations, even though the antibody titers were reduced using this schedule. These studies will facilitate the elucidation of the mechanisms underlying larval protection.

Estudios sobre el anquilostomo duodenal: (con 17 figuras en una plancha) / Studies of the duodenal ancylostoma: (with 17 figures in an iron)

El anquilostomo duodenal es uno de los parásitos intestinales que más daño causa a la humanidad; el cual encontramos en la autopsia de un anémico y lo participamos al "colegio de Médicos", el 18 de septiembre último; así como demostramos que él es responsable de las anemias tan comunes en todo el país. Anchylostomum duodenalis, Dubini, 1838, habita el duodeno, el yeyuno, y rara vez, el íleon del hombre y de los animales superiores. En el presente trabajo citamos: Sinonimias del parásito, Nombres que se le da en distintos países a la enfermedad producida por el mismo; Descubrimiento, origen y distribución geográfica; Clasificación zoológica, forma, dirección y dimensiones; anatomía; Diferentes especies de Uncinarias y la común en Venezuela; Reproducción y modo de infección; Diagnóstico diferencial; Profilaxis y al final se incorpora una plancha con las figuras citadas en el trabajo, con surespectiva descripción

Hookworm infection and anemia in adult women in rural Chiapas, Mexico

OBJECTIVE: To describe associations between anemia and hookworm (Necator americanus) infection in hospitalized women in rural Chiapas, Mexico. MATERIAL AND METHODS: We retrospectively reviewed the hospital records of 68 anemic women (defined as having a hemoglobin level <10mg/dl) or with intestinal parasitism, identified through hospital discharge and transfusion records for the calendar year 1999. The medical charts of 86 cases were located, 18 of which were not confirmed as anemia cases. The hospital is located in Altamirano, Chiapas. Characteristics of subjects were compared using Student's t-test (for continuous variables) and the chi2 test (for categorical variables). A p-value <0.01 was used for statistical significance. Chart review and data analysis took place during the year 2000. RESULTS: Fifty percent of women who had stool examinations were infected with N. americanus. Necator often coexisted with other potential causes of anemia, such as pregnancy and hemorrhage. Hemoglobin levels in hookworm-infected women (mean 4.1 g/dl) were significantly lower than in uninfected women (mean 7.0 gm/dl), and Necator prevalence was significantly higher in the anemic women (50 percent) than in the overall hospital population (1.9 percent). CONCLUSIONS: Anemic women should be offered stool testing where Necator is present, and should be considered for antihelminthic treatment even if pregnant. Further investigation is recommended among women in Chiapas, and probably elsewhere in Mexico

Epidemiology of human geohelminth infections (ascariasis, trichuriasis and necatoriasis) in Lushui and Puer Counties, Yunnan Province, China.

Between April and June of 1998, the prevalence and intensity of geohelminth infections caused by hookworm, Ascaris and Trichuris were investigated in two rural Yunnan villages. In Liuku, a village of Lisu indigenous people in Lushui County, there was an overall geohelminth prevalence of 72% (48%, 43% and 16% for hookworm infection, ascariasis, and trichuriasis, respectively). The prevalence of ascariasis was greatest among preschool and school aged children, whereas the prevalence of trichuriasis was greatest among teenagers and the prevalence of hookworm increased until the age of 10-15 and then remained high throughout adulthood. In Linger, a village of Han Chinese, located in Puer County, there was an overall geohelminth prevalence of 77% (30%, 60% and 36% for hookworm infection, ascariasis, and trichuriasis, respectively). The differences in prevalence for hookworm and ascariasis were statistically significant. The prevalence of hookworm in Linger increased steadily with age and did not plateau, but there were no discernible patterns of prevalence versus age for either ascariasis or trichuriasis. Heavy trichuriasis infections were noted to occur in Linger. In both villages, more than 98% of the hookworm infections were of light and moderate intensity. Both by morphologic identification of third-stage infective larvae (L3) from eggs as well as identification of adult hookworms recovered from adult residents after treatment with quantrel, Necator americanus was identified as the exclusive hookworm in each village. Geohelminth infections caused by Ascaris, Trichuris and hookworm remain highly endemic to the rural areas of Yunnan Province in southwestern China.

Minimum effective doses of mebendazole in treatment of soil-transmitted helminths.

Three hundred and fifteen primary school children infected with soil-transmitted helminths were divided into 5 groups. Three groups were treated with 25, 50 and 75 mg mebendazole (MBZ) single dose. One group was given MBZ conventional dose of 100 mg twice daily for 3 days and another group was given albendazole (ABZ) standard dose of 400 mg single dose. Every trial lower MBZ dose 75 mg, 50 mg and 25 mg regimen were highly effective against Ascaris lumbricoides but only moderately effective against Trichuris trichiura and Necator americanus.

Diarreia persistente por Strongyloides stercoralis e ancilostomideos

O achado de nematelmintos como agentes de diarreia persistente e raro. Os autores relatam o caso de uma crianca que desenvolveu diarreia persistente na presenca destes agentes e de varias outras condicoes que propiciam a doenca. Discutem os fatores de risco, a fisiopatologia e o manejo clinico, enfatizando a terapeutica nutricional

Parámetros hematológicos en niños portadores de uncinarias en una población de la provincia de Corrientes / Hematologic parameters in hookworm infested children of a Corrientes province population

Se investigó la prevalencia de enteroparasitosis en 207 escolares de ambos sexos de la población rural de San Cayetano, Corrientes y en los parasitados con uncinaria se evaluó hemoglobina, valores de hierro sérico, capacidad total de fijación de hierro del plasma y saturación de transferrina. Se halló que 171 niños (82 por ciento de la población estudiada) eran portadores de un parásito o más, de los cuales 46 niños (28 varones y 18 mujeres) presentaron examen coproparasitológico positivo para uncinaria. De los 46 niños parasitados con uncinaria, el 67,4 por ciento fueron portadores de Necator americano; 23,91 por ciento de Necator americano + Ancylostoma duodenale; y 8,69 por ciento sólo de Ancylostoma duodenale. Una alta proporción de varones (78,57 por ciento) y de niñas (83,33 por ciento) presentaron anemia; definida con valores de hemoglobina inferiores al percentilo 3 de las tablas de Dallman y Siimes, aunque sólo el 7,14 por ciento de varones y el 11,11 por ciento de niñas presentaron valores de hemoglobina menores de 9 g por ciento. Un 21,42 por ciento de los varones y 33,33 por ciento de las niñas presentaron valores de hierro sérico menores de 35 µg/dl y 28,57 por ciento de varones y 27,77 por ciento de niñas presentaron saturación de transferrina menor de 13 por ciento. Los resultados hallados hacen necesaria la implementación de estrategias destinadas tanto a la disminución como a la prevención de la parasitosis y de la anemia en los niños de esta población rural

Reevaluation de l'efficacite et de la tolerance du Pamoate de Pyrantel dans le traitement de la necatorose au Senegal

L'etude de la tolerance et de l'efficacite du Pamoate de Pyrantel (Vermintel) s'est deroulee au Senegal dans la region de Ziguinchor et a interesse 40 patients parasites par N. americanus. Le Pamoate de Pyrantel a ete administre a la dose de 20 a 25 mg/kg de pc par jour durant 2 jours consecutifs; soit sous forme de comprimes; soit sous forme de suspension buvable. La tolerance du produit a ete excellente dans 65 pour cent des cas et bonne chez les autres (35 pour cent); puisque les effets secondaires ont ete benins et de breve duree. En ce qui concerne l'efficacite du traitement; elle a ete excellente puisque les signes imputables a la necatorose avaient disparu dans 90;4 pour cent des cas a l'examen de controle a J14. Sur le plan parasitologique; en depit d'un taux de guerison de 20;4 pour cent a J14; l'efficacite peut etre consideree comme bonne. En effet; un taux de reduction du nombre d'oeufs excretes de 90;6 pour cent a ete obtenu chez les sujets non gueris; ce qui correspond a une baisse importante de la charge parasitaire. Les resultats ainsi obtenus dans le traitement de la necatorose au Senegal peuvent etre consideres comme satisfaisants. Ils pourraient cependant etre ameliores en administrant des doses plus importantes

The distribution of intestinal helminth infections in a rural village in Guatemala

Fecal egg count scores were used to investigate the distribution and abundance of intestinal helminths in the population of a rural village. Prevalences of the major helminths were 41% with Ascaris lumbricoides 60% with Trichuris trichiura and 50% with Necator americanus. All three parasites showed a highly aggregated distribution among hosts. Age/prevalence and age/intensity profiles were typical for both A. lumbricoides and T. trichiura with the highest worm burdens in the 50-10 year old children. For hookworm both prevalence and intensity curves were convex in shape with maximum infection levels in the 30-40 year old age class. Infected females had higher burdens of T. trichiura than infected males in all age classes of the population; there were no other effects of host gender. Analysis of associations between parasites within hosts revealed strong correlations between A. lumbricoides and T. lumbricoides and T. trichiura. Individuals with heavy infections of A. lumbricoides and T. trichiura showed highly significant aggregation within households. Associations between a variety of household features and heavy infections with A. lumbricoides and T. trichiura are described

Intestinal helminth infections in children under 5 years old from Moyamba District Southern Province; Sierra Leone

An epidemiological survey was carried out in May 1990 to determine the prevalence of intestinal helminth infections in children (0-5years) living in the Moyamba District; Southern Province; Sierra Leone. On the basis of nematode eggs and larvae observed during microscopic examination of stools samples obtained from 305 children; evidence for infections with the following species of helminth (per cent prevalence) was obtained : ascaris lumbricoides (28.2); necator americanus (19.3); trichuris trichiura (10.8); strongyloides fuellborni (8.9); strongyloides stercoralis (4.3) and enterobious vermicularis (0.7)

Identification of necator americanus from a community in Bo; Southern Province; Sierra Leone

Fifty clinically anaemic children aged 6-9 years old were selected in the Bo; Southern Province; Sierra Leone during April 1990. All had their stools examined for stages of intestinal helminth infections. Twenty-one were judged to be positive for hookworm on the detection of eggs in stools. After treatment with lavemisole; 48 hour stool collections were performed on 15 of the heavily infected children. Adult hookworms were isolated from the specimens of 7 individuals; and preserved in 10 per cent aqueous formalin solution. the worms were later examined microscopically and shown to possess ventral cutting plates; fused and bared spicules; and a bifid nature of the tips of the dorsal rays of the male bursa; confirming their identification as necator americanus

Etude epidemiologique des helminthiases intestinales (necatorose; ascaridiose; tricocephalose) dans la vallee de la Kadei (Cameroun)

Les examens coprologiques avec numerotation des oeufs dans les selles; pratiques dans les villages de Boden; Zimbi et colomines situes dans la vallee de la Kadei ou un barrage va etre construit; permettent d'evaluer les prevalences et les charges parasitaires de trois nematodoses intestinales; la necatorose; l'ascaridiose et la tricocephalose; tres repandues dans la region. Ces affections; et en particulier la necatorose; sont plus frequentes chez les femmes que chez les hommes et leurs prevalences sont plus elevees a Boden et a Zimbi en plaine que sur la colline de Colomines. Il est possible que la mise en eau de la retenue; en faisant remonter le niveau de la nappe phreatique; favorise la transmission par le sol de ces affections; notamment a Boden qui sera situe juste au bord du lac

Dinâmica da infecçäo por ancilostomídeos em regiäo semi-árida do nordeste brasileiro / Dynamics of infection from ancylostomatidae in a semi-arid region of Northeastern Brazil

A infecçao ancilostomótica mantém-se com elevada prevalência e ampla distribuiçäo mundial, independente das campanhas realizadas principalmente ao longo da primeira metade deste século. Apesar disto, é evidente o desinteresse pelo financiamento e desenvolvimento de estratégias de controle, refletindo na escassez de pesquisas aplicadas e literatura especializada nos últimos 20 anos. Os achados de larvas e ovos de ancilostomídeos em coprólitos humanos com dataçäo de 7000 anos em associaçäo com a prevalência atual de 19% em populaçöes isoladas na regiäo do semi-árido nordestino (Sudeste do Estado do Piauí), levantou a questäo acerca de quais seriam as estratégias ecológicas para a perpetuaçäo da espécie sob condiçöes ambientais adversas, para entäo propor estratégias viáveis de controle da endemia na regiäo. Com base nos modelos matemáticos desenvolvidos por Anderson & May (1985) para a dinâmica populacional de ancilostomídeo, realizou-se uma série de simulaçoes por computador com o auxílio do programa SOLVER, desenvolvido para resolver equaçoes diferenciais com retardos no tempo. Os resultados apontaram para a populaçao de larvas infectantes como o principal parâmetro favorável à perpetuaçäo da endemia. A estratégia de hipobiose, apesar de sua demonstraçäo como ecologicamente útil e eficaz teria papel secundário. Os resultados obtidos mostraram-se úteis para o estudo da estratégia de perpetuaç o da endemia no semi-árido nos últimos 7000 anos, pois observou-se que o tempo necessário para a populaçäo parasita atingir o equilíbrio é curto em comparaçäo como tempo de permanência das populaçöes humanas na área, dependendo relativamente pouco da estratégia de desenvolvimento e da densidade demográfica da populaçäo hospedeira. O ambiente externo adverso atuando como limitante na sobrevida das larvas parece ser incapaz de impedir a manutençäo e perpetuaçäo da endemia. A capacidade de estabilidade das populaçöes de ancilostomídeos é tanta que a princípio inviabiliza propostas de tratamento com quimioterapia de massa como estratégia de controle, apontando entäo para alternativa do tratamento seletivo dos indivíduos mais infectados, portadores de sintomatologia clínica

Reinfection and infection rates of soil-transmitted-helminths in Kemiri Sewu, Yogyakarta, Indonesia.

A study on the reinfection and infection rates of soil-transmitted helminths was conducted in Kemiri Sewu, Godean District, Sleman Regency, Yogyakarta Special Province, Indonesia, from August 1988 to June 1990. A total 61 individuals rendered Ascaris lumbricoides egg-negative by drug treatment were used in the reinfection study and 412 individuals found negative for Ascaris eggs in the pretreatment stool examination were used for the infection rate study. In both groups, children had higher and faster reinfection and infection rates than adults. The start of reinfection was 4 months after treatment, and the start of infection was at the 1st month. At 20 months after treatment, the reinfection rate of ascariasis was 14.8% and the infection rate was 11.4% among both children and adults. There were 140 subjects rendered Trichuris trichiura egg-negative by drug treatment, and 317 Trichuris egg-negative at the pretreatment stool examination which were used in the reinfection and infection rates studies. In general, the reinfection rates of T. trichiura among adults were higher than those among children. The start of reinfection was 4 months after treatment, and the infection was at the 1st month. At the end of 20 months, the reinfection rate was 36.4% and the infection rate was 21.8% among both children and adults. A total 83 subjects rendered Necator americanus egg-negative by drug treatment and 365 N. americanus egg-negative at pretreatment stool examination were used in the reinfection and infection rate studies. Throughout the study, adults had always higher reinfection and infection rates than children, while adults males had higher reinfection rates than adults females. The start of reinfection was 4 months after treatment, and the start of infection was at the 1st month; they were 25.3% and 9.3% respectively. At the end of 20 months, the reinfection rate was 65.1%, and the infection rate was 47.9% among both children and adults.