Measuring exposure to Schistosoma japonicum in China. III. Activity diaries, snail and human infection, transmission ecology and options for control

We used activity diaries and snail detection to relate water contact and Schistosoma japonicum infection among a cohort of 178 residents on two islands in the Dongting Lake, China. Water exposure to each of 12 mapped water zones around the islands was calculated (m(2) min/day) for each subject. Infected Oncomelania hupensis hupensis snails in this area are focal and were found in only five of the 12 zones, with the highest rate being 5.7%. Thirty-one subjects (17%) were re-infected with a mean intensity of 63.2 epg. Mean water contact was 7.9 m(2) min/day; 98% of water exposure was due to economic activity and only 2% due to swimming or bathing, washing and other necessities of daily life. Males had more exposure and infection than females (P<0.05). Infected subjects had more exposure (10.2 m(2) min/day) than those not infected (7.44 m(2) min/day) (P<0.05). Compared with uninfected subjects, those infected had 2.9 times more exposure in infected-snail zones (P<0.01). Also, human infection intensity (epg) correlated well with exposure to infected snail zones (r=0.552, P<0.01). People <20 years old had the highest re-infection (21.4%) and intensity (3.77 epg). Median exposure for 20-49-year-olds (9.00 m(2) min/day) was nearly double that of those aged <20 or >50 years old (5.5 m(2) min/day). We conclude that map-referenced water contact and snail evaluation boosts accuracy of activity-diary measurements in large transmission foci for the Asian schistosome. Protecting against faecal contamination of snail inhabited sites, and against occupational exposure for island residents, should be a priority of future research. Potential strategies for migrating buffaloes and families living on visiting fishing boats are explored.     

日本血吸虫病人群获得性免疫与再感染研究 Ⅰ.洞庭湖区一个洲岛型疫区血吸虫病流行病学调查研究

本文报告了湖南省洞庭湖一个洲岛型血吸虫病流行区1996年居民病情调查结果。该洲岛由大（青山Qingshan）、小（严家山Yanjiashan）二岛所组成。共检查居民1909人，受检率为72．2％，Kato－Katz法阳性率大岛为14．6％；小岛为23．7％。大岛血吸虫感染有两个高峰年龄组（25岁—35岁和45岁—55岁）；小岛年龄组感染高峰略有后移。感染者人群感染度（EPG）轻、中、重分别为71．1％、21．3％和76％。肝、脾肿大率分别为21．9％和1．3％。感染率与人群感染度无直接相关；重感染度人群的肝肿大率及腹泻率高于其它组；渔民血吸虫感染率最高（22．4％）；学生的感染度最重（EPG220）。结果表明：该地目前所采用的选择性人群化疗的防治措施未能达到理想的防治效果，宜进一步加强综合防治力度。     

Outbreak of vivax malaria in areas adjacent to the demilitarized zone,South Korea, 1998

Malaria had been eradicated in the Republic of Korea (South Korea) by the late 1970s. In 1993, a soldier was infected with Plasmodium vivax malaria in the Demilitarized Zone (DMZ; the border area between North and South Korea), and since then, the number of cases has been steadily increasing year after year. In 1998, 3,932 vivax malaria cases were microscopically confirmed, affecting 2,784 (70.8%) soldiers (including discharged soldiers) and 1,148 (29.2%) civilians. These cases occurred throughout the year, peaking in July (30.1%) and August (30.5%). Most of the patients were infected in areas in or near the DMZ. Taking into consideration entomologic, socioecologic, and epidemiologic factors, it is postulated that there has been an epidemic of malaria in North Korea since 1993, with the number of cases increasing yearly; the continuous infiltration across the DMZ from North Korea of infected female mosquitoes of the vector species Anopheles sinensis resulted in an outbreak of vivax malaria in the DMZ of South Korea.     

Vivax malaria: a continuing health threat to the Republic of Korea

Vivax malaria reemerged in the Republic of Korea in 1993. Most of the cases occurred among soldiers in the region adjacent to the Demilitarized Zone (DMZ) until 1995. To determine the rate of dispersion of vivax malaria, we evaluated its epidemiologic characteristics. Of 13,903 cases of vivax malaria reported in 2000, 40.1% (5,577) were reported among Republic of Korea military personnel, 26.2% (3,641) among veterans discharged less than two years from the military, and 33.7% (4,685) among civilians. Cases of vivax malaria have rapidly increased annually among counties bordering the DMZ, and have spread to approximately 40 km south of the DMZ. Chemoprophylaxis administered to military personnel may have been responsible for the decreasing number of cases among the Republic of Korea military population. The first mosquito-transmitted cases appeared in early June. Therefore, chemoprophylaxis should be instituted in early April to reduce the number of infected mosquitoes. Extensive intervention is warranted to reduce the spread of vivax malaria in the Republic of Korea.     

Treatment with a single dose of albendazole improves growth of Kenyan schoolchildren with hookworm, Trichuris trichiura, and Ascaris lumbricoides infections

We studied the growth of primary schoolchildren with hookworm (87%), T. trichiura (97%), and A. lumbricoides (49%) who received a single 400 mg dose of albendazole or an identical placebo. Children were allocated at random to placebo (PL, n = 72) or albendazole (A, n = 78) groups, treated, and re-examined 6 months later. The A group gained significantly more than the PL group in weight (1.3 kg), percent weight for age (4.5% age points), percent height for age (0.5% age points), percent weight for height (4.3% age points), percent arm circumference (2.9% age points), and in triceps and subscapular skinfold thicknesses (1.2 mm). The PL group showed significant decreases between exams in percent weight for age, percent height for age, percent weight for height, percent arm circumference for age, and skinfold thicknesses for age. The A group had highly significant increases (P less than 0.0002) in all of these parameters except height for age. From Exam 1 to 2, the A group exhibited decreases (P less than 0.0002) in geometric means eggs per gram of feces (epg): for hookworm, means = 1,183 epg at Exam 1 vs. 136 epg at Exam 2 (67% egg reduction); for T. trichiura, means = 2,857 epg at Exam 1 vs. 1,061 epg at Exam 2 (28% egg reduction); and for A. lumbricoides, means = 86 epg at Exam 1 vs. 2 epg at Exam 2 (91% egg reduction). The PL group had a borderline increase in geometric means hookworm egg count, no significant change in T. trichiura egg count, and a small but significant decrease in A. lumbricoides egg count. Decreases in intensities of all infections were significant predictors of growth improvement. Hookworm egg count entered the equations for all 6 measurements, and A. lumbricoides and T. trichiura entered 4/6 equations. Single dose treatment with albendazole, despite continual exposure to infection, can permit improved growth rates in areas where intestinal helminths and protein-energy malnutrition are highly prevalent.     

Different chest radiographic findings of pulmonary paragonimiasis in two endemic countries

We compared the chest radiographic findings of patients with pulmonary paragonimiasis in the Lao People's Democratic Republic (PDR) with a report from Korea. The clinical and radiological characteristics of 50 confirmed Laotian pleuropulmonary paragonimiasis patients were studied between March 2003 and June 2007. In 49 patients, the chest radiographs showed abnormal findings (98%). Pulmonary parenchymal abnormalities were found in all 49 patients, whereas pleural effusion was only found in 11 patients (22%). The three most common intraparenchymal findings were multiple small cysts (90%), irregular linear densities (68%), and nodular opacities (40%). The numbers of patients who had these three findings were significantly different from the Korean report (P < 0.001). In conclusion, radiographic findings of pulmonary paragonimiasis may vary among countries.     

Use of modified McMaster method for the diagnosis of intestinal helminth infections and estimating parasitic egg load in human faecal samples in non-endemic areas

Summary  A modified McMaster method has been used for the diagnosis and estimating helminth egg load in human faecal samples obtained from random consecutive patients in the areas non-endemic for helminth infections (Slovak Republic, North West Russia). Both positive and negative findings were in a 100 % concordance to those obtained with a reference method accepted in clinical diagnostic laboratories (microscopy of the native stool smear). The McMaster method was efficient in detecting nematode eggs in patients’ stool samples with egg load varying from very low (15–60 epg for T. trichiura) to moderate (1650–4500 epg for A. lumbricoides). Therefore, this method may be successfully (and with a better technical feasibility) used for the diagnosis of intestinal helminth infections in non-endemic areas, with further quantitative analysis of the sample when required.     

Status of Plasmodium vivax malaria in the Republic of Korea during 2001-2003

The Republic of Korea experienced a re-emergence of Plasmodium vivax malaria in 1993. The incidence of this disease increased rapidly through 2000 with its geographic distribution expanding from the vicinity near the Demilitarized Zone to the adjacent outlying areas. However, the number of cases of P. vivax malaria since that time period has decreased. A total of 2,538 cases occurred in 2001, and this decreased to 1,761 cases and 1,164 cases in the two subsequent years. A total of 5,463 cases of P. vivax malaria were reported from 2001 through 2003; 25.26% (1,380) were reported among Republic of Korea military personnel, 27.48% (1,501) were among veterans who had been discharged from the military within two years, and 47.26% (2,582) were among the civilian population. Mosquito control activities by the North Korean and South Korean governments, chemoprophylaxis of Republic of Korea Army personnel, and the low level of Anopheles mosquitoes in 2001 may have been factors responsible for the decreasing number of malaria cases. However, local transmission might have taken place in urban regions of the malaria-risk areas that are within 30 km south of the Demilitarized Zone. Extensive intervention and continued surveillance are warranted to prevent the epidemic from re-expanding and to eliminate this disease in the Republic of Korea.     

Correlates of resistance to gastrointestinal nematode infection in Nigerian West African dwarf sheep

ObjectiveTo investigate correlates of resistance to GI nematode infection in Nigerian West African dwarf (WAD) sheep.MethodsThirty three sheep were randomly assigned to two groups, A (n=27) which were used for experimental infections, and B (n=6) which served as uninfected control. Each infected animal received weekly escalating infections with infective larvae (60% Haemonchus contortus (H. contortus) and 40% Trichostrongylus colubriformis (T. colubriformis) for 4 weeks. The responses of all the infected and control sheep were assessed by faecal egg count (FEC), worm burden (Wb), packed cell volume (PCV), body weight (Bwt), and body condition score (BCS). On the basis of their individual faecal egg output, Lambs in group A with epg ≤1 000 on any sampling day were classified as low faecal egg count (LFEC) phenotype (n = 16), those with epg between 1 000 and 10 000 as intermediate (n=5) and lambs with epg > 10 000 as high feacal egg count (HFEC) phenotype (n=6).ResultsThe difference between the FEC classes was highly significant (P=0.001). The BCS and weight gained at the end of the experiment by the control and LFEC sheep was significantly higher (P≤0.05) than those of the intermediate and HFEC phenotypes. There was a significant and negative correlation between the parasitological measures and the trio of BCS, PCV and Bwt of sheep.ConclusionThe result of the study indicated that the FEC, weight gain, PCV, and BCS are correlates and potential selection criteria of GI nematode resistant WAD sheep.     

The Association between Symptomatic Rotavirus Infection and Histo-Blood Group Antigens in Young Children with Diarrhea in Pretoria,South Africa

Objectives: Recently, histo-blood group antigens (HBGAs) have been identified as receptors or attachment factors of several viral pathogens. Among rotaviruses, HBGAs interact with the outer viral protein, VP4, which has been identified as a potential susceptibility factor, although the findings are inconsistent throughout populations due to HBGA polymorphisms. We investigated the association between HBGA phenotypes and rotavirus infection in children with acute gastroenteritis in northern Pretoria, South Africa. Methods: Paired diarrheal stool and saliva samples were collected from children aged ≤ 59 months (n = 342) with acute moderate to severe diarrhea, attending two health care facilities. Rotaviruses in the stool samples were detected by commercial EIA and the rotavirus strains were characterized by RT-PCR targeting the outer capsid VP7 (G-type) and VP4 (P-type) antigens for genotyping. Saliva-based ELISAs were performed to determine A, B, H, and Lewis antigens for blood group typing. Results: Blood type O was the most common blood group (62.5%) in this population, followed by groups A (26.0%), B (9.3%), and AB (2.2%). The H1-based secretors were common (82.7%) compared to the non-secretors (17.3%), and the Lewis antigen positive phenotypes (Le^(a+b+)) were predominant (54.5%). Blood type A children were more likely to be infected by rotavirus (38.8%) than any other blood types. P[4] rotaviruses (21/49; 42.9%) infected only secretor individuals, whereas P[6] rotaviruses (3/49; 6.1%) only infected Le^(a−b−), although the numbers were very low. On the contrary, P[8] rotaviruses infected children with a wide range of blood group phenotypes, including Le^(a−b−) and non-secretors. Conclusions: Our findings demonstrated that Lewis antigens, or the lack thereof, may serve as susceptibility factors to rotaviral infection by specific VP4 genotypes as observed elsewhere. Potentially, the P[8] strains remain the predominant human VP4 genotype due to their ability to bind to a variety of HBGA phenotypes.     

Prevalence of Toscana virus antibodies in residents of two Ionian islands, Greece

The prevalence of Toscana virus (TOSV) IgG antibodies was determined among 128 residents of two Greek islands in the Ionian Sea, Corfu and Cephalonia. In total, 47.7% of tested persons had TOSV IgG antibodies; 51.7% among residents of Corfu and 39% among residents of Cephalonia. The prevalence was higher among persons older than 60 years, who were living in the coastal areas, while no relation with occupation was observed. The high seroprevalence, combined with the high antibody titers observed, suggest that TOSV, or an antigenically-related virus, circulates or has been circulating extensively in the region.     

Prevalence of antibodies to the circumsporozite protein of Plasmodium vivax in five different regions of Korea

Malaria has recently re-emerged in the Republic of Korea (ROK), but only few malaria seroprevalences were reported. We obtained 1014 serum samples from inhabitants of five regions of ROK during the high transmission season between June and August in 2001. The levels of anti-circumsporozoite protein (CSP) antibody were assessed in samples using an indirect enzyme-linked immunosorbent assay (ELISA). The highest IgG seroreactivity against Plasmodium vivax recombinant CSP antigen was found among male residents of Cheolwon gun (13.5%), then Incheon (4.7%). The IgG seroreactivity from other regions ranged from 0.0% to 2.0%. These epidemiological data of seroprevalence in five regions of Korea showed a similar pattern to the annual incidence of malaria in these respective regions. The prevalence of antibodies increased with age, suggesting that the age and area-related prevalence patterns reflected differences in the inoculation rates between age groups and geographic regions. Seroprevalence and annual incidence were positively correlated in some areas of Korea.     

The effect of the number of stool samples on the observed prevalence and the infection intensity with Schistosoma mansoni among a population in an area of low transmission

Examination of faecal material by Kato Katz (KK) technique is a widely used approach for the diagnosis of intestinal schistosomiasis, particularly in epidemiological surveys. However, this technique lacks diagnostic sensitivity in individuals with low infection intensity or in low endemic areas. In the total population (TP) of 1265 individuals prevalence and infection intensity were established by examining two KK slides. A representative subset of 305 individuals, denominated experimental group (EG), was defined to assess the comparative advantage of an increased sampling effort using the KK technique. In addition stools of the participants of the EG were examined by the formol ether centrifugation technique. The proportion of all positive stool examinations detected by both methods among the experimental group served as reference value for prevalence (diagnostic 'gold' standard). Prevalence of schistosomiasis among TP based on two KK slides was 12.5%. Prevalence among the EG varied from 13.8%, based on one KK slide, over 27.2 based on 10 KK slides of three stool samples to 35.4% as value for the diagnostic 'gold' standard. The comparison of values for prevalence, stratified by age, revealed significant elevated numbers for all age groups, and interestingly, an extension of the highest prevalence levels until an age of 50 years. The overall infection intensity in eggs per gram (epg), calculated as geometric mean, was 83 epg for the TP based on one KK slide, 78 epg for the GE based on one KK slide and 28 epg based on 10 KK slides of three stool samples. In summary our data demonstrate that control programmes based on the examination of a single KK slide, as it is the case in Brazil, tend to underestimate significantly the prevalence and overestimate infection intensity. This applies especially for low endemic areas, where the efficacy and cost-effectiveness of such programmes become questionable. Our data also indicate that the possible solution of this problem lies in targeted mass treatment including age groups with the highest proportions of those infected. This will give high sensitivity together with sustainability and suitability under field conditions.     

Reovirus-like agent and enterotoxigenic Escherichia coli infections in pediatric diarrhea in the Philippines.

Of 82 children hospitalized with diarrhea in the Philippines during January-June 1976, 14 (17%) had infections due to a reovirus-like agent as determined by detection of viral particles in stools by electron microscopy (12 [15%] of 82) and/or by a rise in titer of antibody to the serologically related Nebraska calf diarrhea virus (eight [20%] of 39). Escherichia coli producing heat-labile enterotoxin were found in six (7%) of 82 ill children and two (4%) of 49 healthy control children, while E. coli producing heat-stable enterotoxin were isolated from three children with diarrhea and two without gastroenteritis. Thirty-eight percent of enterotoxigenic E. coli isolated from children with diarrhea, but only 6% of isolates from healthy control, were of serotypes similar to those of enterotoxigenic E. coli isolated in previous studies of these pathogens by other investigators in geographically diverse areas (serotypes O6:H16, O8:H9, and O78:H12) (P less than 0.05). Eight (10%) of the children had infections with multiple enteric pathogens.     

Helicobacter pylori status,endoscopic findings,and serology in HIV-1-positive patients

We have carried out a large prospective study of the frequency ofH. pylori infection and HIV-1 status in a community of ex-drug abusers including subjects with (N=210) and without (N=259) upper gastrointestinal symptoms, endoscopy and serology. Control groups were patients with upper gastrointestinal symptoms not at high risk of HIV-1 infection (N=219) and asymptomatic blood donors (n=322).H. pylori was present in 52% of symptomatic community resident having endoscopy and 55% of the control patients with symptoms but not at high risk of HIV-1 infection.H. pylori was less common in HIV-1-positive patients (40%) than those who were negative (66%;P<0.001). In patients with AIDS (33%), the frequency ofH. pylori infection was reduced compared to HIV-1-positive patients without AIDS (53%;P=0.05). All the residents with AIDS had upper gastrointestinal symptoms. In community residents, peptic ulcer was always associated withH. pylori infection. ByH. pylori serology, there was no difference in the frequency of infection in asymptomatic residents (56%) whether HIV-1 positive (55%) or HIV-1 negative (58%) compared with those residents with symptoms. Overall,H. pylori was less common in HIV-1-positive residents (49%) than those who were HIV-1 negative (61%;P<0.05). This difference was due mainly to the low frequency of infection in residents with AIDS (33%).H. pylori infection is common in HIV-1 positive patients, and only slightly reduced when compared with at-risk HIV-1-negative subjects. Peptic ulcer is associated withH. pylori in HIV-1 infection. Serology is a reliable marker ofH. pylori infection in HIV-1-positive patients, including those with advanced disease.     

The impact of population level deworming on the haemoglobin levels of schoolchildren in Tanga, Tanzania

The impact of albendazole (400 mg) and praziquantel (40 mg/kg body weight) treatment of schoolchildren was compared with placebo according to the presence of anaemia (haemoglobin concentration < 11. 0 g/dl) and heavy (> 5000 epg) or light (< 5000 epg) hookworm egg load. The study was conducted in rural Tanga. Medication was administered in September 1994 and children were followed-up in January 1995. Overall, anthelminthic treatment reduced the fall in haemoglobin concentration compared with that observed in the placebo group (- 0.11 g/dl vs. - 0.35 g/dl; P = 0.02). Anthelminthic treatment was of greatest benefit to the 9% of children with both anaemia and heavy hookworm egg load (+ 0.67 g/dl vs. - 0.67 g/dl) and was also of significant benefit to the 38% of children with anaemia and light hookworm egg load (+ 0.07 g/dl vs. - 0.21 g/dl). It was of no significant benefit to children who were not anaemic. This study suggests that single-dose anthelminthic treatment distributed in schools in this area achieves haematological benefits in nearly half of children infected with S. haematobium and geohelminths (37% of total population).     

Detection of the Hb Quong Sze mutation in a Chinese family by selective amplification of the alpha 2-globin gene and restriction map analysis with Msp I.

The polymerase chain reaction technique combined with restriction map analysis with Msp I and hybridization with synthetic oligonucleotide probes has been used to identify Hb Quong Sze [alpha 125(H8)Leu----Pro] in a Chinese family in Guangxi (Quong Sze), P. R. China. Our data and those described in an earlier publication (1) indicate that the Hb Quong Sze carriers originate from the same province of the People's Republic of China, namely Guangxi.     

广东省重要岛屿恙虫病东方体血清流行病学调查

目的在广东省5岛屿开展恙虫病东方体血清流行病学调查并进行血清分型,为制定恙虫病防治策略提供依据。方法1998年5月～2003年8月在广东省南澎列岛、南澳岛、万山群岛、硇洲岛和雷州半岛等岛屿采集驻岛官兵、居民及啮齿动物血清,采用免疫荧光法检测抗体并进行血清学分型。结果687份人血清中抗恙虫病抗体阳性95份,阳性率13.83%,其中岛屿居民抗体阳性率为26.91%,军人为3.63%,差异有统计学意义(P<0.05)。检测508份鼠血清,抗恙虫病东方体抗体阳性率为57.87%,其中褐家鼠为有时鼠种。恙虫病东方体血清型以Karp株为主,占50.90%。结论广东省5岛屿均为恙虫病疫源地,恙虫病东方体血清型以Karp株为主。     

Detection of the HB Quong SZE Mutation in a Chinese Family by Selective Amplification of the α2-Globin Gene and Restriction Map Analysis with MSP I

The polymerase chain reaction technique combined with restriction map analysis with Msp I and hybridization with synthetic oligonucleotide probes has been used to identify Hb Quong Sze [α25(H8)Leu→Pro] in a Chinese family in Guangxi (Quong Sze), P.R. China. Our data and those described in an earlier publication (1) indicate that the Hb Quong Sze carriers originate from the same province of the People's Republic of China, namely Guangxi.     

Pig as a favorable animal for Taenia saginata asiatica infection

The epidemiology of Taenia saginata in some parts of Asia is confusing, in that beef does not appear to be the source of infection. In some areas, beef is either not available or not eaten raw, whereas pork at times is eaten uncooked. In light of this situation, we have exposed pigs and other animals to infection with strains of T. saginata to establish their ability to serve as intermediate hosts. Eggs of Taiwan Taenia, Korea Taenia, Indonesia Taenia, Thailand Taenia, Philippines Taenia, Ethiopia Taenia, and Madagascar Taenia were fed to 83 pigs of three strains: 43 Small-Ear Miniature (SEM), 34 Landrace Small-Ear Miniature (L-SEM), and 6 Duroc-Yorkshire-Landrace (DYL). We also fed the eggs to 10 Holstein calves, 17 Sannean goats, and 4 monkeys (Macaca cyclopis). We succeeded in infecting SEM (infection rate 88%, cysticercus recovery rate 19.1%), L-SEM (83%, 1.1%), and DYL (100%, 0.3%) pigs with Taiwan Taenia; SEM (100%, 1.7%), L-SEM (100%, 5.6%), and DYL (100%, 0.06%) pigs with Korea Taenia; SEM (100%, 22%) and L-SEM (100%, 1.6%) pigs with Indonesia Taenia; SEM (75%, 0.06%) pigs with Thailand Taenia SEM (100%, 11%) pigs with Philippines Taenia; SEM (80%, 0.005%) pigs with Ethiopia Taenia; SEM (100%, 0.2%) pigs with Madagascar Taenia. Holstein calves became infected with Taenia from Taiwan (100%, 1.1%), Korea (100%, 0.03%), Thailand (100%, 0.2%), and the Philippines (100%, 6%); however, the cysticerci of Taenia from Korea, Thailand, and the Philippines were degenerated and/or calcified. Sannean goats became infected with Taenia from Taiwan (33%, 0.01%) and Korea (50%, 0.02%), while monkeys became infected with Taenia from Taiwan (50%, 0.01%). However, the cysticerci were degenerated and/ or calcified. Therefore, these strains of pig seem to be favorable animal models for experimental studies of T. saginata-like tapeworms, with the SEM pig the most favorable.