Intestinal protozoan and helminth infections and control of soil-transmitted helminths in Malay school children

Preclinical and Clinical Characteristics of the Trichuricidal Drug Oxantel Pamoate and Clinical Development Plans: A Review

Soil-transmitted helminths (Ascaris lumbricoides, hookworm and Trichuris trichiura) infect about one-fifth of the world's population. The currently available drugs are all highly efficacious against A. lumbricoides. However, they are only moderately efficacious against hookworm and poorly efficacious against T. trichiura. Oxantel, a tetrahydropyrimidine derivative discovered in the 1970s, has recently been brought back to our attention given its high efficacy against T. trichiura infections (estimated 76% cure rate and 85% egg reduction rate at a 20 mg/kg dose). This review summarizes the current knowledge on oxantel pamoate and its use against T. trichiura infections in humans. Oxantel pamoate acts locally in the human gastrointestinal tract and binds to the parasite's nicotinic acetylcholine receptor (nAChR), leading to a spastic paralysis of the worm and subsequent expulsion. The drug is metabolically stable, shows low permeability and low systemic bioavailability after oral use. Oxantel pamoate was found to be safe in humans, with only a few mild adverse events reported. Several clinical trials have investigated the efficacy of this drug against T. trichiura and suggest that oxantel pamoate is more efficacious against T. trichiura than the currently recommended drugs, which makes it a strong asset to the depleted drug armamentarium and could help delay or even prevent the development of resistance to existing drugs. We highlight existing data to support the use of oxantel pamoate against T. trichiura infections.

Efficacy and reinfection with soil-transmitted helminths 18-weeks post-treatment with albendazole-ivermectin, albendazole-mebendazole, albendazole-oxantel pamoate and mebendazole

Background

Preventive chemotherapy with albendazole or mebendazole is the current strategy to control soil-transmitted helminth (STH) infections (i.e. Ascaris lumbricoides, hookworm and Trichuris trichiura). STH reinfections, in particular A. lumbricoides and T. trichiura occur rapidly after treatment with the standard drugs. However, their low efficacy against T. trichiura, made an accurate assessment of reinfection patterns impossible.

Methods

In 2013 a randomised controlled trial was conducted on Pemba Island, Tanzania. School-aged children diagnosed positive for T. trichiura, were randomly allocated to (i) albendazole-ivermectin; (ii) albendazole-mebendazole; (iii) albendazole-oxantel pamoate; or (iv) mebendazole. Here we report the efficacy [cure rates (CR) and egg-reduction rates (ERR)], reinfection rates and new infections determined 18 weeks post-treatment.

Results

For a total of 405 children complete baseline and follow-up data were available. Similar to the efficacy determined after 3 weeks, 18 weeks after treatment albendazole-oxantel pamoate showed a significantly higher efficacy against T. trichiura (CR: 54.0 %, 95 % CI: 43.7–64.0; ERR: 98.6 %, 95 % CI: 97.8–99.2) compared to the other treatment arms. Children treated with albendazole-oxantel pamoate or albendazole-ivermectin had fewer moderate infections compared to children treated with albendazole. The reinfection rates 18 weeks post-treatment among all treatment arms were 37.2 % for T. trichiura (95 % CI: 28.3–46.8), 34.6 % for A. lumbricoides (95 % CI: 27.3–42.3) and 25.0 % for hookworms (95 % CI: 15.5–36.6).

Conclusion

The moderate reinfection rates with STHs 18 weeks post-treatment support the concept of regular anthelminthic treatment in highly endemic settings. Combination chemotherapy might achieve decreased morbidity in children since in the albendazole plus oxantel pamoate and albendazole plus ivermectin treatment arms only few moderate T. trichiura infections remained. Further trials should investigate the long term efficacy of albendazole-oxantel pamoate (i.e. 6 and 12 month post-treatment) and after several rounds of treatment in order to develop recommendations for appropriate control approaches for STH infections.

Trial registration

Current Controlled Trials ISRCTN80245406

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-016-1406-8) contains supplementary material, which is available to authorized users.

The prevalence of recurrent abdominal pain in 11- to 16-year-old Malaysian schoolchildren

OBJECTIVE

To determine the prevalence of recurrent abdominal pain (RAP) among Malaysian school children aged from 11 to 16 years.

METHODOLOGY

A preliminary cross-sectional survey in which three urban schools and three rural schools were selected randomly. Two classes were selected randomly from each year. A questionnaire was given to each child asking him or her about whether they had experienced abdominal pain occurring at least three times over a period of at least 3 months, interfering with normal daily activity. 1 Interfering with normal daily activity was defined as missing school and/or having to stop doing a routine daily activity on account of the pain. Girls whose pains were related to periods were excluded. After the forms had been completed, each child was again interviewed to ensure that Apley's criteria1 was fulfilled in cases of RAP.

RESULTS

The overall prevalence of RAP among 1549 schoolchildren (764 boys; 785 girls) was 10.2% (95% confidence interval (CI), 8.8-11.8). There appeared to be a higher prevalence in rural schoolchildren (P = 0.008; odds ratio (OR) 1.58), in those with a lower family income (P < 0.001; OR 2.02) and in children whose fathers have a lower educational attainment (P = 0.002; OR 1. 92). There were no significant differences in the prevalence of RAP among children of different sex, age, ethnic group and family size.

CONCLUSION

: In spite of differences in time and culture, the overall prevalence of 10.2% found in this study is similar to that determined by Apley.1 There are significant differences in the prevalence of RAP between children from rural and urban schools, among children with different family incomes and among children whose parents have different educational backgrounds.