Parasitic infections,anaemia and nutritional status: a study of their interrelationships and the effect of prophylaxis and treatment on workers in Kwale District,Kenya

A study was conducted between January and August 1979 on 150 male roadworkers in Kwale District in the coastal lowlands of Kenya. At the baseline examination 59% had hookworm (mean of 227 epg ± 541), 38% had infections of Schistosoma haematobium (mean 52 ± 82 ova per 10 ml urine), 23% had a blood film positive for malarial parasites, 47% had anaemia (Hb below 13g/dl), and 31% had a percentage weight for height below 80% of a reference value for healthy men. It was found that anaemia was significantly associated with hookworm infections and egg counts. Three interventions were evaluated. These consisted of providing pyrantel pamoate for hookworm to all men, treating the S. haematobium infections with metrifonate, and giving weekly chloroquine prophylaxis for suppression of malaria to one group of men. A final examination conducted 16 weeks later showed a significant improvement in haemoglobin levels in anaemic men treated for hookworm and in those receiving chloroquine compared with those receiving placebos. Multiple regression analyses revealed that both hookworm and S. haematobium egg counts were associated with anaemia at the baseline examinations, that factors related to the treatment of hookworm and prophylaxis for suppression of malaria were related to haemoglobin increases in anaemic men, and that successful treatment of urinary schistosomiasis was associated with weight gain. The feasibility of the interventions was good and the costs moderately low.     

Current status of schistosomiasis and soil-transmitted helminthiasis in Beyla and Macenta Prefectures, Forest Guinea

A cross-sectional survey was undertaken in children aged 9-14 years in Beyla and Macenta Prefectures, Forest Guinea. Stool samples were examined by Kato-Katz and urine samples were examined by the centrifugation method. The overall prevalence and intensity of infection was 66.2% and 462.4 eggs per gram of faeces (epg) for Schistosoma mansoni, 21.0% and 17.8 eggs per 10 ml of urine for S. haematobium, 51.2% and 507.5 epg for hookworm, 8.1% and 89.1 epg for Ascaris lumbricoides and 2.4% and 16.7 epg for Trichuris trichiura. The overall prevalence of schistosomiasis (S. mansoni and/or S. haematobium) was 70.7%. The prevalence of schistosomiasis was similar to those reported in the 1990s in the region; however, the prevalence of soil-transmitted helminths has since fallen. These findings illustrate the need for schistosomiasis control in Guinea.     

A comparative study of the nutritional status,parasitic infections and health of male roadworkers in four areas of Kenya

The nutritional status, parasitic infections and general health of 801 male roadworkers living in four different areas of Kenya, namely, the highlands, coastal lowlands, Lake Victoria basin and the semiarid north-west, were investigated. Undernutrition was common in all areas but was most marked among men in the semi-arid area. Anaemia was most prevalent in the coastal lowlands where 41% of men had a haemoglobin level less than 13·0 g/dl. Hookworm eggs were seen in the faeces of 40% of all men and in 69% of samples collected in the coastal lowlands. The Lake Victoria basin was a significant focus of infection with Schistosoma mansoni, 51% of faecal samples containing its eggs; S. haematobium also occurred but was most common in the coastal lowlands. Stages of Plasmodium spp. were most commonly observed in blood smears collected from men near Lake Victoria and the coast, two significant foci of malaria. An analysis of variance was used to examine the relationship between variables and indicated that the most significant association was between hookworm infections and low haemoglobin levels.     

Dynamics of Schistosoma haematobium infection in a Gambian community. III. Acquisition and loss of infection

During a three-year period of effective control of Schistosoma haematobium transmission by molluscicide application the mean number of S. haematobium ova passed by subjects in the treated area fell in an exponential manner which suggested that the mean life span of the worm was 3·4 years. Parallel observations were made in a similar but untreated area. A comparison of the observations in these two areas suggested that in the untreated area subjects of all ages acquired infection during the course of the study. At the end of the study over 50% of the egg output in most age groups in the untreated area appeared to come from worms acquired during the preceding three years. There were substantial differences between age groups in the amount of infection acquired. Children, aged between eight and ten years at the end of the study, appeared to be passing perhaps a thousand times more ova from worms acquired during the preceding three years than were middle-aged subjects. Preliminary observations suggest that age- and sex-related differences in the pattern of water contact may not fully account for age- and sex-related differences in the rate of acquisition of infection and its prevalence. The probable significance of protective immunity in the epidemiology of schistosome infections is discussed.     

Association of bacteriuria and urinary nitrosamine formation with Schistosoma haematobium infection in the Qalyub area of Egypt

In Egypt, bladder cancer incidence is high in areas where the prevalence and intensity of Schistosoma haematobium infection is also high. Experimental evidence shows bladder carcinogenesis to be a multi-stage process which can be accelerated by many factors. N-nitroso compounds, some of which are known bladder carcinogens, can be formed from amine precursors and nitrate in urine during some bacterial infections. In experimental animals the growth of nitrosamine-induced urothelial cancers is accelerated by damage to the urothelium caused by S. haematobium infections, and by analogy in man this could account for the lower peak age of incidence of this cancer in Egypt by comparison with Europe.The present study was designed to investigate whether bacterial infection of the urinary tract was common in areas of endemic schistosomiasis and whether N-nitrosamines were regularly found to be associated with bacteriuria. Urine samples from young men in the Qalyub area of Egypt and from an adjacent Delta region were analysed for S. haematobium ova, the nature and intensity of any bacterial infection, nitrate and nitrite, and total N-nitroso compounds plus volatile N-nitrosamines. A relatively high prevalence of bacteriuria was found in young men with schistosomiasis and low levels of N-nitroso compounds were present in all specimens. When the groups were sub-divided on the basis of the ability of their bacterial flora to reduce nitrate to nitrite (the latter is required for the nitrosation of amine precursors to N-nitroso compounds), significantly higher levels of N-nitroso compounds were found in S. haematobium-infected individuals also infected with nitrate-reducing bacteria by comparison either with uninfected controls (p < 0 · 0005) or with those infected with non-nitrate-reducing bacteria (p <0 · 001).The results show N-nitroso compounds to be present in the urines of young men in areas of endemic S. haematobium infection in Egypt, and elevated levels of urinary N-nitroso compounds to be associated with infection of the urinary tract by various species of nitrate-reducing bacteria.     

Prevalence of Schistosoma intercalatum and S. haematobium Infection among Primary Schoolchildren in Capital Areas of Democratic Republic Of S?o Tomé and Príncipe,West Africa

Background

A parasitological survey of Schistosoma haematobium and S. intercalatum infection among primary schoolchildren in capital area of Democratic Republic of São Tomé and Príncipe (DRSTP) was undertaken.

Methods

Subjects with positive infection were confirmed by the detection of S. haematobium ova in the urine or S. intercalatum ova in the stool by using centrifugation concentration or merthiolate-iodine-formalin concentration method. Totally, 252 urine and stool samples, respectively, were obtained from apparently healthy schoolchildren, of which 121 from boys (9.8 ± 1.4 yr) and 131 from girls (9.7 ± 1.3 yr).

Results

None of participating schoolchildren were found having S. haematobium ova in the urinary specimen. While, among 4 primary schools studied, only schoolchildren from Saint Marçal were detected with S. intercalatum ova in the fecal specimen, making the overall prevalence of S. intercalatum infection among schoolchildren was 2.4% (6/252) and girls had insignificantly higher prevalence (3.1%, 4/131) than that (1.7%, 2/121) in boys (χ² = 0.5, P = 0.5).

Conclusion

Water control and sanitation as well as snails eliminated by molluscicides are urgently needed to reduce S. intercalatum infection in DRSTP inhabitants.     

Water-contact patterns in relation to Schistosoma haematobium infection.

Water-contact observations were carried out on a population exposed to Schistosoma haematobium in a village situated on a man-made lake, Lake Volta, Ghana.     

Epidemiology and transmission dynamics of Ascaris lumbricoides in Okpo village,rural Burma

A horizontal study of the prevalence of Ascaris infection was carried out on the total population of Okpo village near Rangoon, Burma, where a similar study had been conducted 13 years earlier. Ascaris eggs in faeces were counted after treatment with levamisole on a random sample of 50% of the infected population to give information to the numbers of epg of stool, the mean worm burden per host and the distribution of worms in the community. The information on prevalence is compared with that of the previous survey. Various population parameters of Ascaris were calculated to estimate the transmission dynamics of A. lumbricoides. In addition, chemotherapeutic regimes, assessed on the proportion of the human population to be treated and the time interval between treatments, are proposed to reduce transmission below a critical threshold. The findings are compared with those of other studies and the probable mode of occurrence and maintenance of Ascaris infection in Okpo village are discussed.     

Urinary Schistosomiasis in Urban and Semi-Urban Communities in South-Eastern Nigeria

Background

In view of the massive rural-to-urban migration in Nigeria, investigations on transmission of urinary schistosomiasis were carried out in urban and semi-urban communities in Nike Lake area of Enugu State, Nigeria.

Methods

Urine samples of school children were tested for micro-haematuria using reagent strips followed by microscopic examination for Schistosoma haematobium eggs. Water contact sites were also identified and sampled for snails.

Results

The overall prevalence of S. haematobium eggs in school children was 4.64%. The mean intensity of infection was 1.14 ± 0.41 eggs/10ml urine. Males had insignificantly higher prevalence and intensity of S. haematobium infection than females. The youngest age group (4-7 years) had no infection. The prevalence of micro-haematuria (6.2%) was higher than that of microscopy, and this correlated positively with prevalence (r = 0.65, P < 0.01) and intensity (r = 0.50, P < 0.01) of the infection. Potential intermediate host of human shistosome collected were: Bulinus globosus, B. senegalensis and Biomphalaria pfeifferi. However, only B. globosus shed cercariae of S. haematobium, with a snail infection rate of 0.73%. Transmission was in the dry season coinciding with the drying of wells.

Conclusion

The results revealed that urinary schistosomiasis is prevalent, and that B. globosus and not B. truncatus as previously reported is the main intermediate host of urinary schistosomiasis in this part of Enugu State.     

Long-term efficacy of single-dose oral treatment in schistosomiasis haematobium

A two-year follow-up was conducted in children who had been the subjects of a six-month double-blind trial in the single-dose treatment of Schistosoma haematobium infection. The trial had assessed therapeutic efficacy of three oral preparations—praziquantel 40 mg/kg, metrifonate 10 mg/kg, and the “combination” (concurrent niridazole 25 mg/kg and metrifonate 10 mg/kg administration).Reduction in urinary egg excretion remained high up to follow-up at two years, based on a comparison of pre- and post-treatment geometric mean counts—praziquantel 96·9% (n = 96 at six months, 51 at two years); the ‘combination’ 93·9% (n = 97 at six months, 48 at two years); and metrifonate 90·3% (n = 92 at six months, 49 at two years). The differences in percentage reduction were not significant (p>0·1). However, a significantly greater reduction in egg ouput was produced by praziquantel (81·7%) and the ‘combination’ (82·5%) than by metrifonate (54·2%), on comparing pre- and post-treatment arithmetic mean counts (p<0·01).A significantly smaller percentage of subjects were excreting ≥125 ova/10 ml urine two years after treatment with praziquantel (10·3%), compared to treatment with the ‘combination’ (25·7%) and metrifonate (35·8%) (p<0·01). The cure rate was significantly higher in the praziquantel group (47·4%) compared to the ‘combination’ (24·7%) and metrifonate (17·4%) groups, for the six to 24-month follow-up period (p<0·001).The pattern and level of transmission had contributed to the long-term efficacy recorded in this study.     

Mixing of Schistosoma haematobium strains in Ghana.

In Ghana, Schistosoma haematobium exists as two strains, one transmitted by Bulinus rohlfsi and the other by B. globosus. In Anyaboni, a resettlement town, where the field station of the UNDP/WHO Schistosomiasis Research and Control Project is located, the residents contract the ”rohlfsi” strain of the parasite from the Volta Lake and the ”globosus” strain from a stream near the town. The present studies indicate that there is mixing of the two parasite strains on a community and an individual basis. In Anyaboni, the parasite developed well in both B. rohlfsi and B. globosus. In another village 25 km from Accra, where B. globosus was the only vector, the parasite developed well in B. globosus but was refractory in B. rohlfsi. In a village near the Volta Lake where B. rohlfsi was the sole vector, the parasite developed well in B. rohlfsi but was refractory in B. globosus. However, complete separation of the two strains is uncommon in Ghana because extensive mixing has already occurred owing to migration of people and snails.     

Effect of School Based Treatment on the Prevalence of Schistosomiasis in Endemic Area in Yemen

Background

Schistosomiasis and soil transmitted infection is a major health problem of children from rural areas of developing countries including Yemen. In an attempt to reduce this burden, the Ministry of Public Health and Population in Yemen established in 2002 a programme for Schistosomal, soil transmitted infection control that aimed to reduce morbidity and prevalence rates of Schistosomiasis, and Soil transmitted helminthes to less than 5% by 2015. The study was conducted to assess the current prevalence and intensity of schistosomal infection among schoolchildren in rural areas of the Taiz governorate after 6 years of running National Control Programme.

Methods

Grade 3 schoolchildren from Shara''b Al-Raona district of Taiz Governorate were examined for infections with Schistosoma mansoni using Modified Kato–Katz method and S. haematobium applying filtration method in 1998/1999, comparing the prevalence and intensity of infection with base line study, which was done 6 years ago.

Results

The S. mansoni prevalence in the study population was 31%, while the prevalence of S. haematobium was 18.6%. This result considerably is similar to the prevalence of base line study. The intensity of mild, moderate and severe infection for S. mansoni reached to 15.9%, 60.6% & 23.5% respectively. The severity of S. haematobium infection was 68.4%. It was exceptionally found that the prevalence of S. haematobium is increased.

Conclusion

The high prevalence of schistosomiasis and low effectiveness of control programme against schistosomal infection in the study area demands consideration of alternative treatment approaches.     

Schistosomiasis in school-age children in Burkina Faso after a decade of preventive chemotherapy

ObjectiveTo assess the impact of a decade of biennial mass administration of praziquantel on schistosomiasis in school-age children in Burkina Faso.MethodsIn 2013, in a national assessment based on 22 sentinel sites, 3514 school children aged 7–11 years were checked for Schistosoma haematobium and Schistosoma mansoni infection by the examination of urine and stool samples, respectively. We analysed the observed prevalence and intensity of infections and compared these with the relevant results of earlier surveys in Burkina Faso.FindingsS. haematobium was detected in 287/3514 school children (adjusted prevalence: 8.76%, range across sentinel sites: 0.0–56.3%; median: 2.5%). The prevalence of S. haematobium infection was higher in the children from the Centre-Est, Est and Sahel regions than in those from Burkina Faso’s other eight regions with sentinel sites (P < 0.001). The adjusted arithmetic mean intensity of S. haematobium infection, among all children, was 6.0 eggs per 10 ml urine. Less than 1% of the children in six regions had heavy S. haematobium infections – i.e. at least 50 eggs per 10 ml urine – but such infections were detected in 8.75% (28/320) and 11.56% (37/320) of the children from the Centre-Est and Sahel regions, respectively. Schistosoma mansoni was only detected in two regions and 43 children – i.e. 1 (0.31%) of the 320 from Centre-Sud and 42 (8.75%) of the 480 from Hauts Bassins.ConclusionBy mass use of preventive chemotherapy, Burkina Faso may have eliminated schistosomiasis as a public health problem in eight regions and controlled schistosome-related morbidity in another three regions.     

Treatment with praziquantel in a patient with schistosomiasis and chronic renal failure

The pharmacokinetics of praziquantel in a uraemic patient, infected with Schistosoma haematobium, undergoing haemodialysis, was studied by repeated analyses of serum, urine and dialysis fluid. The results indicate the possibility of treating advanced cases of infection with S. haematobium with the normally recommended doses.     

An evaluation of the ELISA for schistosomiasis in a hospital population

In order to evaluate the ELISA for schistosomiasis under the conditions of clinical practice, 1576 hospital patients were tested using a crude soluble Schistosoma mansoni egg antigen. Test sensitivity in detection of S. mansoni was found to be 96·2% and in S. haematobium 92·3%. The predictive value of positive results was high, reaching 88% at antibody levels three or more times the screening level. The test was considered by clinicians to be valuable for diagnosis and patient management, though it did not distinguish active from recently treated infections. Of 37 apparently false positive schistosome ELISA results only seven could be attributed to other helminth infections. Another nine patients had hepatitis. It is suggested that the antigens and antibodies of the two diseases are mutually cross-reactive, since reports have suggested a high increase of HBsAg patients with schistosomiasis.     

Skin sensitivity reactions in Nigerian children with bronchial asthma

Skin sensitivity reactions to a variety of antigens in 290 unselected urban Nigerian children suffering from bronchial asthma of varying severity, are reported. The percentages of positive skin reactions to the first four antigens were as follows: Ascaris (25%), Dermatophagoides pteronyssinus (21%), house dust (12%) and feathers (12%). The sizes of reaction were generally smaller than those reported in European and American children. While the relatively high sensitivity to Ascaris was probably fortuitous, further studies are needed to evaluate the actual role, if any, of the parasite in bronchial asthma affecting the African child. The relatively low rate of positive skin reactions indicate that, at present, skin sensitivity tests are of limited value in the identification of aetiological factors in asthma affecting Nigerian children. The development of local materials for skin testing may however enhance the usefulness of this investigation in future.     

Cross-species protection: Schistosoma mansoni Sm-p80 vaccine confers protection against Schistosoma haematobium in hamsters and baboons

The ability of the Schistosoma mansoni antigen, Sm-p80, to provide cross-species protection against Schistosoma haematobium challenge was evaluated in hamster and baboon models. Pronounced reduction in worm burden (48%) and in tissue egg load (64%) was observed in hamsters vaccinated with recombinant Sm-p80 admixed with glucopyranosyl lipid adjuvant-stable emulsion (GLA-SE). Similarly, in baboons, the Sm-p80/GLA-SE vaccine produced a 25% reduction in S. haematobium adult worms and decreased the egg load in the urinary bladder by 64%. A 40% and 53% reduction in fecal and urine egg output, respectively, was observed in vaccinated baboons. A balanced pro-inflammatory (Th17 and Th1) and Th2 type of response was generated after vaccination and appears indicative of augmented prophylactic efficacy. These data on cross-species protection coupled with the prophylactic, therapeutic and antifecundity efficacy against the homologous parasite, S. mansoni, reinforces Sm-p80 as a promising vaccine candidate. It is currently being prepared for GMP-compliant manufacture and for further pre-clinical development leading to human clinical trials. These results solidify the expectation that the Sm-p80 vaccine will provide relief for both the intestinal and the urinary schistosomiasis and thus will be greatly beneficial in reducing the overall burden of schistosomiasis.     

The suppression, by Helisoma duryi, of the cercarial production of Schistosoma mansoni-infected Biomphalaria pfeifferi.

Biological control of the intermediate hosts of Schistosoma mansoni and S. haematobium by means of a competitor snail, Helisoma duryi, has been suggested. In the present laboratory study, the influence of H. duryi on the relationship between the parasite and the intermediate host was investigated. The results indicated that H. duryi behaves as a “decoy” if it is present when Biomphalaria pfeifferi is exposed to the miracidia of S. mansoni, and that the continued presence of H. duryi in the aquarium after B. pfeifferi has been exposed greatly reduces cercarial production. When these two species were present in equal numbers, cercarial production was reduced by 95.9% in comparison with a control group.     

Bilharzial asthma: Bronchial asthma in Schistosoma infection

Three cases of bilharzial asthma are described as a type of allergic reaction dependent on constitutional factors and substances liberated by Schistosoma (haematobium or mansoni).One of these cases showed febrile asthma with simultaneous urticarial rashes.The two other observations concerned blood relations (uncle and nephew). It was possible to prove that the asthmatic paroxysms had no relation to lesions of the lungs brought about by the parasite, the pulmonary bilharziasis. In all kinds of infections with S. haematobium and mansoni X-ray examination constantly reveals pulmonary involvement.The causal relationship between bilharzia infection and asthma is demonstrated by the complete parallelism in the course of both diseases subsequent to specific therapy.The allergic nature of this kind of asthma has been proved by its association with urticaria and the constitutional and hereditary character of this allergy, which is very infrequently encountered, by its occurrence in relatives.The resistance of the atypical bilharziasis of the liver and lungs to fuadin treatment is noted.