A recurring theme of the NTD sessions at this year’s ECCMID conference was the relationship between NTDs, HIV and STDs. Figures for each seem to overlap, as do some of the physical signs.
Each complements the other’s existence. For example, an NTD’s (such as schistosomiasis) symptoms make target areas (in this case epithelium) vulnerable and as a result ease the path of sexually transmitted disease (STDs) and HIV agents into the body. And with that, the person becomes coinfected by more than one dangerous illness.
The management of one, therefore, should take into account the others’. Here is a summary of what the ECCMID conference highlighted, particularly for schistosomiasis.
The connection is there
Many studies have looked into the relationship in prevalence of individual NTDs and HIV/AIDS. Most have found there is huge overlap in infection and, in the case of soil-transmitted helminths, this was also linked to location and education. In the case of dengue, however, HIV-postive patients had less severe dengue symptoms and this was put down to interactions between disease pathways or the antiretroviral treatments.
Research into some NTD coexistence with HIV has led to specific guidance for treating patients. Some studies have found that HIV-positive patients have a higher rate of Chagas disease reactivation, and once coinfected, patients must be treated more aggressively with both Chagas (benznidazole) and antiretroviral HIV drugs.
For urogenital schistosomiasis, most reports have shown that adults think they have an STD. This is somewhat understandable because of the signs they have in common, and some studies have found that schistosomiasis predisposes to STDs, particularly in women.
But the key difference is that urogenital schistosomiasis is not sexually transmitted and can cause more dangerous consequences than most STDs. It is worrying to think that in most cases, the patients will not seek help unless the symptoms of the apparent STD alter their daily life. One doctor reported that a patient left her bleeding until she reached blood haemoglobin level 6 (normal range of haemoglobin for a man is 13.5-17.5 g/dl; for a woman is 11.5-15.5 g/dl – so this is life-threatening); and even then only came to report her case because she felt “tired”.
What came first: NTD or HIV?
Coinfection with different NTDs is not uncommon and research shows having one NTD makes you more prone to other infections too. “This is down to the resultant compromised immune system and vulnerable body tissue,” said one researcher.
In 2009, the World Health Organization (WHO) hosted a meeting which set about raising awareness and stressing the importance of research into the likelihood that the treatment of urogenital schistosomiasis could contribute to the control of HIV transmission.
Up to 75% of females in endemic countries suffer from urogenital schistosomiasis and a study in 2006 found these women are three times more likely to have HIV too. In Zimbabwe, 73% of females suffer from urogenital schistosomiasis and of these, 49% have HIV too. This is no coincidence.
So if there is a definite link between the two infections, which triggered the onset of the other? One study set about finding out what came first: HIV or urogenital schistosomiasis?
When comparing those who had urogenital schistosomiasis with and without HIV, studies found that there is no difference between the lesions each develop. Lesions are not more numerous, larger or have more contact bleeding. With these results, it was concluded that genital schistosomiasis probably came first and predisposed to HIV. Subsequent studies have supported this finding.
One study found that in those who become HIV-infected, co-infection with schistosomiasis may accelerate HIV disease progression and aid viral transmission to sexual partners. They suggest that more attention is needed for this “pressing yet neglected public health issue”.
Integration of management initiatives
A report in PLoS NTDs last year looked into the relationship between various NTD infections and HIV prevalence. By reviewing literature, they concluded the overlap is extensive and relationship between each NTD and HIV varied slightly.
Soil-transmitted helminth infections (ascariasis, hookworm, trichuriasis), and schistosomiasis, for example, either promote susceptibility to the HIV virus or worsen the clinical course and progression of AIDS. Visceral leishmaniasis (VL), on the other hand, has emerged as an important opportunistic infection of HIV/AIDS.
Evidence of the biological relationship between NTDs and HIV/AIDS means that effective management of HIV/AIDS may require the control of NTDs and this is possible given the success of past programmes which have targeted coinfection with HIV and other infections such as TB. There is a lot in common between current management of HIV and management of NTDs and the integration of initiatives is key to targeting both growing burdens.