An Israeli, Ethiopian, US and Swedish team of researchers has reported new evidence that treating intestinal worms can lead to a reduction in HIV viral load. The Israeli group, led by Professor Zvi Bentwich at the Hebrew University in Jerusalem, had previously reported similar findings based on treatment given to HIV-positive Ethiopian migrants to Israel. This new evidence is stronger, since the treatment for the worms was given with fewer other changes happening in people’s lives.
56 asymptomatic HIV positive adults who had not been diagnosed with AIDS-related diseases (26 men, 30 women) were recruited for this study, 31 of whom had intestinal worms at the time of enrolment, diagnosed from stool samples, while 25 did not. All 56 were treated (in case some infestations were missed) with 200mg of albendazole daily for three days on three occasions – at baseline, 3 and 6 months. In addition, those who were diagnosed with schistosomiasis were treated with 40mg/kg of praziquantel. Eggs in stool samples were used as a measure of the level of worm infestation.
Most of the worms detected were Trichurus trichiura (14 cases) or Ascaris lumbricoides (13); schistosomiasis was rarer, with S. mansoni (4) and S. stronglyoides (2).
Viral load tests were done in Chicago, USA, on blinded plasma samples; CD4 counts were also measured, in Ethiopia, using a FACScount system.
At baseline, there was a weak, non-significant association between viral load and having worms or not; however, among those who did have worms, there was a highly significant correlation between the number of worm eggs in stools and viral load.
Some worm infestations were successfully treated and others were not, or people were reinfested by the same or a different kind of worm. In 28 people it was possible to compare viral loads before and 6 months after treatment, in three groups: 12 successfully treated, 6 unsuccessfully treated, 9 with no infestation. (6 people died or were lost to follow-up; for others, viral load results were not available at both time points.)
Viral load fell in the treated group, by -0.36 log copies/ml on average, but rose by 0.69 log in the persistent or re-infestation group and by 0.14 log in the apparently worm-free group (a difference of almost 1 log, equivalent to antiviral effect of dual combination therapy). The results achieved statistical significance (p=0.04) despite the small numbers involved. Since even the worm-free group had received anti-worm treatment, it was not a direct antiviral effect of the treatment. There was no significant change in CD4 cell count in any group between baseline and month 6, however.
The authors observe that some studies of schistosomiasis have not seen such effects; they suggest that Trichurus and Ascaris infestations have a shorter-lasting effect on the immune system, so that treatment more rapidly leads to a reduction in viral load.
In view of the very large numbers of people with HIV who are infested with intestinal worms and the low cost of treating them, even a modest effect could be of great public health value. However, larger studies are still needed to test the value of de-worming to prevent disease progression and HIV transmission, for example, from mothers to babies. In addition to a direct effect on viral load, treating intestinal worms improves people’s nutritional status, which is also likely to improve their ability to live with HIV.
Wolday D et al. Treatment of intestinal worms is associated with decreased HIV plasma viral load. JAIDS 31: 58-62, 2002.