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.

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

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

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

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.

Uncinariasis infantil como problema de salud pública / Infantile hookworn as a public health problem

El síntoma de la uncinariasis es la anemia ferropriva, la cual es dependiente de la intensidad, la especie de uncinaria, la capacidad del huésped para resistir la infección y de mantener una reserva adecuada de hierro. En latinoamérica tropical, el Necator americanus y con frecuencia menor Ancylostoma duodenale son muy prevalentes. La infección se confirma demostrando los huevecillos en las heces; la diferenciación de las especies requiere del examen de los gusanos adultos o del estudio microscópico de las larvas. La prevención de la contaminación fecal del suelo, el saneamiento, la educación del público incluyendo el uso de zapatos y la quimioterapia específica más la suplementación dietética del hierro y proteínas, son medidas preventivas muy efectivas

Human intestinal helminthiases in East Timor.

In a study of 210 people from all age groups in the Venilale District of East Timor, 49% had Ascaris lumbricoides, 1% Trichuris trichiura and 67% hookworm infection. There were high Ascaris infection rates among some of the children, but the Trichuris and hookworm rates were almost uniformly low. The factors responsible for these rates are enumerated, and the complex interaction of the factors is discussed. The relative lack of shade and the well-drained limestone soil are probably in large measure responsible for the generally low helminth prevalence. Ascaris was the principal cause of eosinophilia. It was not possible to relate any other haematological or serological findings to the helminths. Apart from the high Ascaris infections in young children, it is not thought that these helminths constitute a heatlh problem.