Hookworm re-infection rate and efficacy of single-dose albendazole among pregnant women in Debre Elias District,Northwest Ethiopia: A single-arm trial

Background

Hookworm infestation caused by nematode parasites and transmitted by larval penetration by contact with contaminated soil and by ingestion of soil containing infective larva, ¹ is one of the neglected parasitic diseases in humans. It has remained a major public health concern throughout many countries of the world where access to anthelmintic is limited.^2,3 A single dose oral anthelminthic (Albendazole 400 mg, levamisole 2.5 mg/kg, Mebendazole 500 mg, or Pyrantel 1mg/kg) is well-known to be safe and effective, and is recommended by WHO for treatment of pregnant and lactating women. ⁴

Hookworm infects over a billion people worldwide with a prevalence range of 20–80% in low- and middle-income countries. ⁵ Infections reduce working capacity and increase maternal and fetal morbidity and mortality. ⁴ Globally in 2010, an estimated 438.9 million people are infected with hookworm, resulting in 4.98 million years lived with disability (YLDs). ⁶ In Ethiopia, it has been recognized as the major cause of anaemia in poor communities. ⁷ However, understanding the benefits of managing hookworm infection in pregnancy has lagged behind other major causes of maternal anaemia. This could be due to low coverage and access to anthelmintic treatment in maternal health programmes in many countries.

Intestinal parasitosis is one of the ten top infectious diseases in Debre Elias district. Hookworm is the most common as the majority of the people in this area are barefooted and actively work on the fertile red soils. ⁸ Albendazole has been used for several years for the treatment of hookworm; however, hookworm prevalence has not been reduced to the expected level in our study area. Albendazole efficacy and post-treatment hookworm re-infection pattern have not been studied in pregnant women. There is a need for the periodical evaluation of re-infection.

Materials and methods

A community-based cross-sectional study was conducted from February to September 2021 in Debre Elias District, which is located 340 km from Addis Ababa. It is bordered by Machakel Woreda in the North, Gozamin Woreda in the East, Oromia region in the South, and Dembecha in the West The District is divided into two major agroecological zones. The moist mid-altitude (Woinadega) comprises 91% (2100–2300 MASL) and the warm moist land (Kolla) comprises 9% (1500–2100 MASL). The average annual temperature is 14.9°C. The total population is 100800 of whom 49,955 are male and 50,840 are female.

A total of 363 participants selected from five kebeles (Debre Elias District) were enrolled. Participants who were willing to provide a stool sample, and who were not on anthelminthic medication were included, but those in the first trimester and vomiting within 4h of post-treatment were excluded.

A single stool specimen of about 5g was collected from each study participant. Stool samples were transported to the nearby health centre and examined using Kato-Katz thick smear preparations. Participants who were confirmed to have hookworm infection and beyond the first trimester were given a biscuit before the drug was administered and took the same batch and brand of Albendazole (400mg) which was within its expiry date and properly stored based on World Health Organization guidelines. ⁹ The health extension worker and/or pharmacists gave the tablets under direct observation, and each pregnant woman was kept under observation for approximately 4h. They were asked to report any side effects rapidly.

A second stool specimen at 14–21 days post-treatment was taken. Pregnant women who were unable to bring a specimen at this time were followed up to 1 or 2 days later. The same laboratory method (Kato-Katz thick smear preparations) was used in the follow-up survey.

Pregnant women who tested positive during the baseline survey and negative following 14–21 days of post-treatment were tested 18–24 weeks after post-treatment to assess the re-infection rate. Data were entered and analyzed using SPSS version-24 software.

Results

Of the 263, all participated in the baseline screening. Their mean age was 27.7 years (range 17–42). More than half (77.1%) were multigravida and 68.3% were in the second trimester.

'Some 132 (36%) participants were found infected with hookworm during the baseline survey. Of these, 115 were eligible for treatment and received albendazole. After 14–21 days of post-treatment, 89/109 become hookworm negative with a cure rate of 81.7%, and the egg reduction rate (ERR) of 92.5% (Figure 1).

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Figure 1.

Diagram representing cure rate and re-infection rate of hookworm among participants.

Participants who were hookworm positive at the baseline and tested negative after 14–21 days of post-treatment were followed for 18–24 weeks to assess re-infection status. Hookworm was detected in 18/84 (21.4%). (Figure 1).

Discussion

In Ethiopia, anthelminthics are periodically administered to children below five years old and pregnant women to control infection and combat associated morbidity. ¹⁰ Despite the mass drug administration, previous studies reported that 71.2% of schoolchildren were infected with hookworm in our study area. ⁸ This figure is alarming and the efficacy of single-dose albendazole is therefore questionable. The cure rate of single-dose albendazole against hookworm infection has been reported to be in the range of 33%-95% according to a systematic review and meta-analysis. ¹¹ Our cure rate and egg reduction are comparable with a study conducted among school children in South Africa, with cure rate of 78.8% and ERR of 93.2%, and similar re-infection rate ranges 10%-21% after 16–18 weeks of post-treatment. ¹² Studies in Cameroon ¹³ and China ¹⁴ also demonstrated a significant re-infection pattern with hookworm after single-dose albendazole treatment, thus highlighting the need for control programmes apart from preventive chemotherapy.