Treatment and prevention of trichuriasis : efficacy of albendazole in disadvantaged children at Rawsonville Primary School, Western Cape Province, South Africa

Arendse, Vera Jane (2000-12)

Thesis (MSc)--Stellenbosch University, 2000.

Thesis

ENGLISH ABSTRACT: Children in socioeconomically disadvantaged communities in the Western Cape and elsewhere in South Africa are frequently infected by Trichuris trichiura. Although albendazole and mebendazole are listed as essential drugs for treatment of humans, it is well known that trichuriasis is relatively refractory to anthelmintic treatment. There are some reports that mebendazole is more effective against Trichuris and it is available as generics that are relatively cheap. On the other hand, albendazole is better for hookworm and may have some effect against Giardia duodenalis, which is common in the same communities. Moreover, albendazole is used in a deworming programme in KwaZulu-Natal, at a dose o f400 mg stat, given once or twice a year depending on the health region in that province. In terms of diagnosis, infection by intestinal helminthiasis can be determined and monitored by simple, non-invasive, sustainable and cost effective methods. The epidemiological significance of high prevalence extends far beyond the worms per se because they are an index of environmental conditions that pose a risk of several other diseases. These include infection by organisms that can cause epidemics of enteric disease. These facts pertain within a deteriorating milieu in terms of human ecology, because the informal sector of the population is burgeoning under dynamic forces that include urbanisation, migration, poverty and disease. The study reported in this thesis had three main objectives within the context and concepts of the realities described in the previous two paragraphs. The first was to review and consider all information on trichuriasis that could be detected in the literature, and to relate the result to South African needs. The second was to test efficacy of albendazole against trichuriasis in children from a community where it is the predominant worm infection, by means of a well designed and controlled study. Finally, it was necessary to consider other results associated with treatment. These included possible drug resistance and effects on growth, eosinophilia, iron status and toxicity. The literature survey established that South Africa lags behind many other developing countries in defining and addressing the problem of helminthiasis as a whole. The conventional epidemiology of trichuriasis as described in the literature is based mainly on studies in the West Indies. Surveys completed recently in the Western Cape Province of South Africa confirm some of the epidemiological concepts, with two notable exceptions. First, the age-related prevalence peaked in children who were 14 years old in a suburb of Cape Town. This is older that in West Indian children. The second difference is probably more important and was detected in children at schools serving the informal sector o f Khayelitsha. This is densely populated and the sanitation is often not effective and is sometimes totally lacking. The distribution of egg counts in 316 Khayelitsha children was not overdispersed to low counts, which is perceived as invariably the situation in the West Indies. In the Khayelitsha survey, approximately 25% of children had more than 10 000 eggs per g of faeces. The randomised controlled treatment trial tested a series of four albendazole treatments, at doses of400, 800 and 1200 mg (given as 400 mg/day), repeated at intervals of approximately four months in matched groups of children. Results indicate that mass deworming programmes in South Africa should not use albendazole at a dose o f400 mg stat for control of infection by Trichuris trichiura. The package insert of the product tested (Zentel®, SmithKline Beecham) recommends that "in heavy mixed infestation involving Trichuris, a single daily dose may be inadequate and the dose may be given for three consecutive days". This statement is not accurate because even when infection by Trichuris was not intense, as defined internationally in terms of egg counts per g of faeces, and it was the only helminth present, the cure rate achieved by repeated doses of 400 mg of albendazole was not satisfactory. Moreover, 48% (15/31) of treated children remained continuously infected, although egg counts were clearly reduced. This result demonstrates that continuous use of a dose of 400 mg which is the maximum stat dose permitted in South Africa, is likely to facilitate development of true genetic resistance to albendazole by T. trichiura. Doses of 800 and 1200 mg were more efficacious and continuous infection reduced to 21% (9/43) and 2.5% (1/39), respectively. A dose of 800 mg for routine use in mass deworming programmes, as 400 mg/day, can be recommended on the basis of sufficiently efficacious treatment, simplification of compliance, and reduction of cost. The frequency of treatment within such programmes should probably be three times per year when prevalence of severe infection exceeds 10% ("severe infection" is defined internationally as an egg count of more that 10 000 per g of faeces). When severe infection is less frequent, treatment could be less often, but more definitive research of this aspect is necessary under local conditions. There was some evidence that incidence increased seasonally during summer and autumn in the community concerned. A range of other results was recorded. The possibility of genetic resistance to albendazole by Trichuris trichiura was not excluded. There was significant reduction of eosinophiha during treatment with albendazole. This may have immunological implications for incidence, prevention and progression of other diseases. Treatment appeared to be beneficial in terms of growth and iron status, but there was not sufficient statistical power to confirm this. No evidence of toxicity at the highest dose (1200 mg given as 400 mg/day for three days) was detected.

AFRIKAANSE OPSOMMING: Kinders in sosio-ekonomiese agterblewe gemeenskappe in die Wes-Kaap en ook elders in Suid-Afrika toon gereelde infeksies met Trichuris trichiura. Albendazool en mebendazool word gelys as noodsaaklike medikasie vir menslike behandeling, maar dit is wel bekend dat Trichuris relatief moeilik is omte behandel. Daar word gerapporteer dat mebendazool meer effektief is teen Trichuris en maklik beskikbaar is as goedkoper generiese medikasie. Albendazool, aan die ander kant, is effektief teen haakwurm en kan ook ‘n effek het teen Giardia duodenalis, wat voorkom in dieselfde gemeenskappe. ‘n Dosis van 400 mg albendazool, een of twee keer per jaar, word huidelik gebruik in ‘n onwurmingsprogram in KwaZulu-Natal. Die frekwensie van behandeling word bepaal deur die gesondheids streek binne die provinsie. In terme van diagnose, kan infeksie deur intestinale helminte bepaal en gemonitor word deur eenvoudige, nie-invallende, koste effektiewe maniere. Die epidemiologiese betekenis van ‘n hoe voorkoms strek verder as net die wurms omdat hulle ‘n indeks is van omgewings besoedeling wat kan dui op die risiko van verskeie ander siektes. Dit sluit in infeksies deur organismes wat epidemies van enteriese siektes veroorsaak. Hierdie feite pas binne die agteruitgang in terme van menslike ekologie, want die informele sektor van die bevolking is onder dinamiese druk wat verstedeliking, migrasie armoede en siektes insluit. Die studie, waarvan verslag gegee word in hierdie tesis, het drie vemame objektiewe binne die konteks en konsepte van die realiteite soos beskryf in die vorige twee paragrawe. Die eerste objektief was om alle informasie aangaande trichuriase in die literatuur in oorsig te neem en dit in verband te bring met Suid-Afrikaanse behoeftes. Die tweede was om die werksaamheid van albendazool teen trichuriase te toets in kinders van ‘n gemeenskap waar wurm infeksies oorheers, deur middel van ‘n goed beplande en gekontroleerde studie. Laastens was dit nodig om ander resultate, geassosieer met behandeling, in ag te neem. Dit sluit in moontlike weerstand teen die medikasie en die effek op groei, ysterstatus en toksisiteit. Die literatuur oorsig toon dat Suid-Afrika ‘n agterstand het met baie ander ontwikkelende lande om die omslag van die probleem van helminte te bepaal en ook om dit aan te pak. Die konvensionele epidemiologie van trichuriase, soos beskryf in die literatuur, is gegrond op studies in die Wes-Indies. Opnames wat onlangs in die Wes-Kaap gedoen is, bevestig sekere epidemiologiese konsepte met twee vemame uitsonderings. Die eerste is die ouderdoms verwante voorkoms wat ‘n hoogtepunt bereik in 14 jarige kinders in ‘n voorstad van Kaapstad. Dit is ouer as in die Wes-Indiese kinders. Die tweede verskil is miskien meer belangrik en was vasgestel in skool kinders in ‘n informele sektor van Khayelitsha. Dit is ‘n dig bewoonde area met oneffektiewe of ‘n totale gebrek aan sanitasie. Die verspreiding van eier tellings in 316 Khayelitsha kinders was nie oor-versprei tot lae tellings nie, wat andersins die geval in die Wes-Indies was. In die Khayelitsha studie het ongeveer 25% van kinders meer as 10 000 epg stoelgang. Die gekontrolleerde ewekansigheidstoets soos bespreek in hierdie tesis het ‘n reeks van vier albendazool behandelings, by dosisse van 400, 800 en 1200 mg (gegee as 400 mg/dag), herhaal by pouses van ongeveer vier maande in gelyke groepe van kinders, ge-evalueer. Die resultate toon dat massa ontwurmings programme in Suid-Afrika nie die 400 mg dosis vir kontrole van Trichuris trichiura moet gebruik nie. Die pakkie insetsel van die produk wat getoets was (Zentel®, SmithKline Beecham) dui aan dat in swaar gemengde infeksies waar Trichuris betrokke is, ‘n enkele dosis onvoldoende is en dat die dosis vir drie agtereenvolgende dae gegee mag word. Hierdie stelling is onakkuraat want al is die infeksie deur Trichuris nie swaar nie, soos intemasionaal gedefinieer in terme van eier telling per gram stoelgang, en al is dit die enigste intestinale wurm teenwoordig, is die genesingsyfer wat behaal is met herhaalde dossise van 400 mg albendazool nie bevredigend nie. Inteendeel, 48% (15/31) van behandelde kinders was aanhoudend besmet, al was eier tellings duidelik verminder. Hierdie resultaat wys dat herhaaldelike gebruik van ‘n 400 mg dosis, wat die maksimim dosis toelaatbaar in Suid-Afrika is, genetiese weerstand van albendazool deur Trichuris trichiura kan fasiliteer. Die 800 mg en 1200 mg dosis was meer doeltreffend en het herhaalde infeksie verminder tot 21 % (9/43) en 2.5% (1/39) onderskeidelik. Die 800 mg dosis as 400 mg/dag word aanbeveel vir roetine gebruik in massa ontwurmings programme. Dit is meer doeltreffend, behandeling word vereenvoudig en koste word verminder. Die frekwensie van behandeling binne sulke programme moet waarskynlik drie keer per jaar wees wanneer die prevalensie van swaar infeksies meer as 10% is (“swaar infeksie” word intemasionaal gedefinieer, wanneer eier tellings meer as 10 000 eiers per g stoelgang is). As swaar infeksies minder voorkom, kan behandeling minder gereeld wees, maar meer bepaalde navorsing onder plaaslike kondisies is nodig. Daar is sekere bewysse dat insidensie seisoenaal verminder, tydens somer en herfs, in hierdie gemeenskap. ‘n Reeks van ander resultate was ook aangeteken. Die moontlikheid van genetiese weerstand van Trichuris trichiura teen albendazool word nie uitgesluit nie. Daar was ‘n aanmerklike vermindering van eosinophillia tydens behandeling met albendazool. Dit mag immunologiese implikasies vir insidensie, voorkoming en voortgang van ander siektes voorspel. Dit blyk of behandeling groei en yster status bevoordeel het, maar daar was nie genoegsame statistiese mag om dit te bevestig nie. Geen bewys van vergiftiging by die hoogste dosis (1200 mg gegee as 400 mg/dag vir drie dae) is waargeneem nie.

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