Jonathan Mnkai (Mbeya / TZ), Dr. Manuel Ritter (Munich / DE), Jessica Minich (Bonn / DE), Dr. Mkunde Chachage (Mbeya / TZ), Willyhelmina Olomi (Mbeya / TZ), Dr Lucas Maganga (Mbeya / TZ), Dr. Leonard Maboko (Dodoma / TZ), Eric Lelo (Nairobi / KE), Daniel Kariuki (Nairobi / KE), Prof. Dr. Alexander Y. Debrah (Kumasi / GH), Dr. Sacha Horn (Munich / DE), Dr Christof Geldmacher (Munich / DE), Dr. Elmar Saathoff (Munich / DE), Prof. Dr. Michael Hoelscher (Munich / DE), Dr. Kenneth Pfarr (Bonn / DE), Achim Hoerauf (Bonn / DE), Dr. Inge Kroidl (Munich / DE)
Abstract text
Background: Globally, Wuchereria bancrofti accounts for 90% of all lymphatic filariasis cases and is associated with reduced immunity against concomitant infections. Indeed, our previous study described a 2.3 fold increased HIV incidence among individuals with W. bancrofti infection, as measured by the circulating filarial antigen (CFA) of the adult worm. However, the previous study did not measure microfilariae (MF) in the blood of infected individuals, a factor, which is significant because adaptive immune responses in filarial infected individuals differ according to MF status. This new study aimed to retrospectively determine microfilariae status of the participants to assess if the previously described increased HIV susceptibility is associated with the presence of MF in the same cohort.
Methods: CFA positive HIV negative biobanked human blood samples (n=350) were analyzed for W. bancrofti MF chitinase by real time PCR.
Results: The PCR provided a positive signal in 12/350 (3.4%) samples. During four years of follow-up (1109 person years (PY)), 22 study participants acquired an HIV infection. In 39 PY of W. bancrofti MF chitinase positive individuals, three new HIV infections occurred (7.8 cases per 100 PY) in contrast to 19 seroconversions in 1,070 PY of W. bancrofti MF chitinase negative individuals (1.8 cases per 100 PY, p=0.014).
Conclusion: In the subgroup of MF-producing W. bancrofti-infected individuals, the HIV incidence exceeded the previously described moderate increased risk for HIV seen in all filarial infected individuals (regardless of MF status). Compared with W. bancrofti-uninfected persons from the same area the risk to acquire HIV is approximately 10 times higher. compared. If both W. bancrofti-infected subgroups are compared,l the infection with measurable MF is associated with a 4.58 times higher HIV incidence than the W. bancrofti infection without MF in the blood. This study highlights the need to eliminate lymphatic filariasis, not only because of the disabling pathological changes, which can occur, but also because of the impact on susceptibility to HIV and other viruses. Further studies should decipher the mechanisms that are responsible for the increased risk of HIV in microfilaria positive individuals and whether anti-filarial treatment in LF endemic areas can reduce the HIV incidence in filarial infected people.