Effect of Targeted Mass Treatment on Intensity of Infection and Morbidity in Schistosomiasis Mansoni

Mahmoud, A. A. F.; Ouma, John H.; Siongok, T. A.; Houser, H. B.; Warren, K. S.

doi:10.1016/s0140-6736(83)91388-0

Cited by 35 publications

(11 citation statements)

References 16 publications

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“…If this should be the case, then early identification of resurgent infection may be considered by the proposed approach, rather than by repeated community surveys, for timing re-treatment and for targeting it at the most vulnerable groups who frequent the sites monitored. 23 Snail surveys for timing retreatment was previously proposed, 20 because repeated community surveys often result in a progressive decrease in community cooperation. 24 The usefulness of the PCR assay developed in the present study for the proposed purposes remains to be demonstrated by suitable field studies.…”

Section: Discussionmentioning

confidence: 99%

A polymerase chain reaction assay for detecting snails infected with bilharzia parasites (Schistosoma mansoni) from very early prepatency.

Hamburger¹,

He-Na²,

Xin³

et al. 1998

Am J Trop Med Hyg

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Abstract. In the present study, we adapted a polymerase chain reaction (PCR) assay, previously shown by us to be very sensitive for detecting cercariae in water, for the sensitive detection of Schistosoma mansoni DNA in infected snails from early prepatency. Polymerase chain reaction primers were designed based on the 121-basepair highly repeated sequence we previously identified in the genome of S. mansoni. The DNA was prepared from the snails by a simple alkaline extraction procedure, and the PCR assay enabled a clear differentiation between infected and normal snails. Infected snails were detected as early as one day after penetration of a single miracidium. The high sensitivity of the test enabled identification of a single infected snail even when its DNA was pooled with material from up to 99 uninfected snails, thus demonstrating the possibility of mass diagnosis in pools of snails. The assay has the potential for large-scale determination of prepatent infection prevalence in snails, thus offering new possibilities for the evaluation of schistosomiasis transmission and for schistosomiais control, as discussed.Schistosomiasis, is caused in humans by three main species of blood flukes (Schistosoma mansoni, S. haematobium, and S. japonicum) and is transmitted by freshwater snails. It continues to plague many developing countries in the tropics 1 with an estimated 200 million infected people worldwide.Freshwater snails, intermediate hosts of schistosomes, become infected by larvae (miracidia) released from schistosome eggs that reach the water with excreta. After several weeks of asexual multiplication within the snail's tissues, larvae infective to humans by active penetration through the skin (cercariae), are released into the water. Snail infection and contact patterns of humans with water infested with cercariae are important factors in the transmission of schistosomiasis, and risk of infection is normally estimated by detecting infected intermediate hosts in sites where humans come in contact with water. 2 Infection rates in field populations of snails are routinely determined by searching for cercariae shed from snails with patent infection. 3 In contrast, prepatent infections, which can constitute a significant proportion of infected snails populations, 4 are not determined routinely because of a lack of a suitable method. Microscopic examination of crushed snails in search of developing cercariae and intramolluscan-multiplying larvae (the sporocysts) 5 is sometimes used for this purpose but is highly inaccurate at early prepatency, and unsuitable for routine large-scale screening of snail populations. 4 Another approach is to examine nonshedding field snails maintained for several weeks in the laboratory for protracted shedding. However, this method is time-consuming, it cannot be done routinely on a large scale, and it can be highly inaccurate if snails mortality is high. The omission of data on prepatent infections leaves out important information for the evaluation and mathematical modeling of trans...

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Section: Discussionmentioning

confidence: 99%

A polymerase chain reaction assay for detecting snails infected with bilharzia parasites (Schistosoma mansoni) from very early prepatency.

Hamburger¹,

He-Na²,

Xin³

et al. 1998

Am J Trop Med Hyg

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“…[3][4][5] Recognizing that many infected persons may not experience advanced stages of disease, programs began to incorporate measurement of subtle morbidity markers such as anemia, 6,7 and the importance of subtle morbidity indicators has started to gain more attention. 33,34 However, currently, the impact of treatment in S. mansoni-endemic areas is monitored primarily by assessing changes in infection prevalence and intensity and may not truly reflect the impact of treatment on health.…”

Section: Discussionmentioning

confidence: 99%

“…[3][4][5] However, many infected persons may not experience advanced stages of disease but are still likely to have less obvious, but persistent disabilities such as anemia and impaired growth. Consequently, some schistosomiasis control programs began to incorporate measurement of subtle morbidity markers.…”

Section: Introductionmentioning

confidence: 99%

Assessment of Quality of Life as a Tool for Measuring Morbidity Due to Schistosoma mansoni Infection and the Impact of Treatment

Won

Abudho²,

Blackstock³

et al. 2014

The American Society of Tropical Medicine and Hygiene

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Abstract. Recently, health measurements have broadened to include the assessment of quality of life (QOL). This study was conducted to assess whether the short form of the World Health Organization (WHO) QOL questionnaire (WHOQOL-BREF) was an effective tool for measuring morbidity due to Schistosoma mansoni infection and whether it could detect an impact of treatment with praziquantel. A total of 724 adults 18-85 years of age were enrolled. At baseline, S. mansoni prevalence was 73.2% by stool examination and 75.4% by circulating cathodic antigen, and there was no association between infection status and WHOQOL-BREF scores. Six months after treatment, S. mansoni prevalence was lower and the proportion of persons with higher WHOQOL-BREF scores significantly increased among persons who were infected at baseline. However, a similar increase was observed in persons not infected at baseline. In areas of high prevalence, the WHOQOL-BREF may not be able to detect the benefits of schistosomiasis control programs.

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“…The widespread use of drug therapies for reducing the burden of disease caused by helminths (parasitic worms) was introduced several decades ago. 1 Recently, this approach-which treats the entire local at-risk population, not just infected individuals-has been extended to the control of most neglected tropical diseases caused by a heterogeneous group of infectious organisms (Exhibit 1). 2 Widespread drug therapy has had a short-term impact on parasite burden in Africa, Asia, and Latin America.…”

Section: Neglected Tropical Diseases: Moving Beyond Mass Drug Treatmementioning

confidence: 99%

Neglected Tropical Diseases: Moving Beyond Mass Drug Treatment To Understanding The Science

Mahmoud¹,

Zerhouni

2009

Health Affairs

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Neglected tropical diseases (NTDs) represent a major health burden in many developing countries. To date, global efforts to control thirteen parasitic and bacterial infections that affect more than 1.4 billion people have relied on mass drug administration. This singular approach should now be expanded to a more comprehensive suite of tools including coordinated community-based programs, vector control, local training, education, and environmental change. In addition, an intensive basic research agenda is urgently needed to develop effective diagnostic, preventive, and therapeutic interventions to stay one step ahead of the evolutionary adaptation tactics of disease-causing microbes and parasites.

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Effect of Targeted Mass Treatment on Intensity of Infection and Morbidity in Schistosomiasis Mansoni

Cited by 35 publications

References 16 publications

A polymerase chain reaction assay for detecting snails infected with bilharzia parasites (Schistosoma mansoni) from very early prepatency.

A polymerase chain reaction assay for detecting snails infected with bilharzia parasites (Schistosoma mansoni) from very early prepatency.

Assessment of Quality of Life as a Tool for Measuring Morbidity Due to Schistosoma mansoni Infection and the Impact of Treatment

Neglected Tropical Diseases: Moving Beyond Mass Drug Treatment To Understanding The Science

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