The Impact of Antiretroviral Therapy on Malaria Parasite Transmission

Association of first-line combination antiretroviral therapy with malaria among adult HIV-infected persons in Jos, Nigeria: a pilot cross sectional study

BACKGROUND

Malaria and human immunodeficiency virus (HIV) infection coexist in significant numbers in some geographic areas including sub-Sahara Africa (SSA). HIV-infected patients are a World Health Organization (WHO) recognized high risk group for increased malaria morbidity. Majority of HIV-infected patients undertaking treatment in SSA are on WHO recognized first-line combination antiretroviral therapy (cART). Considering the immunity-enhancing capacity of antiretroviral therapies on people living with HIV, this study aimed to explore the association between first-line combination antiretroviral therapy (cART) with malaria parasitaemia and antigenaemia in adult HIV-infected persons and to determine the predictors of malaria antigenaemia in adult persons living with HIV.

METHODS

The study was conducted at the AIDS Prevention Initiative in Nigeria (APIN) Centre, Jos University Teaching Hospital, Jos, Plateau State, from August 2018 to February 2019. Epi Info statistical tool was used to determine the sample size and power of the study. The study population consisted of three groups. The first group comprised first-line cART-experienced adult HIV-seropositive subjects, the second group comprised ARV-naïve HIV-seropositive adults and the third group comprised HIV-seronegative adults. For this pilot study, 60 persons were recruited into each group via convenience sampling. Malaria rapid diagnostic test (RDT) was performed according to manufacturer's instruction for all the study participants using SD Bioline Malaria Ag P.f (HRP2/pLDH) (Standard Diagnostics, Hagal-Dong, Korea). All the study participants also had thick and thin blood film malaria microscopy. Data collected was processed and analyzed using the Stata statistical software version 15 (StataCorp, College Station, Texas). Chi square was used to test the association between malaria and first-line cART exposure. Univariate and multivariate analysis were also done to identify factors that were independently associated with malaria antigenaemia.

RESULTS

A total of 180 persons participated in the study and involved 60 participants recruited in each of the three study groups. Overall, the predominant study participants were females (56.67%), traders (27.78%), secondary school leavers (43.33%) and urban dwellers (88.89%). Their mean age and standard deviation was 37.07 ± 11.53 years. Using malaria microscopy, the prevalence of malaria parasitaemia in ARV-naïve HIV-infected persons was 5% and 0% in the first-line cART-experienced HIV-infected persons as well as the HIV-negative persons. Malaria RDT result was positive in 7/60 (11.67%) of the first-line cART experienced HIV-infected participants, 6/60 (10%) of the ARV-naïve HIV-infected group and 1/60 (1.67%) of the HIV-negative group. Of the seven positive malaria RDT results in those on first-line cART, five persons were receiving zidovudine/lamivudine/nevirapine (AZT/3TC/NVP) while the remaining two were receiving tenofovir disoproxil fumarate/lamivudine/efavirenz (TDF/3TC/EFV), thus making an antigenaemia proportion of 16.67% and 6.67% respectively. Being an HIV-infected person on first-line cART (OR = 16.20, p = 0.04), having a headache (OR = 6.21, p = 0.03) and non-usage of window nets (OR = 3.74, p = 0.05) were found to be predictors of malaria antigenaemia.

CONCLUSION

Malaria parasite burden in HIV-infected persons on first-line cART is lower than that observed in ARV-naïve HIV-infected persons. Our study suggests that TDF/3TC/EFV may be associated with lower malaria antigenaemia when compared with AZT/3TC/NVP and can be considered an alternative first-line antiretroviral regimen in malaria-endemic regions.

Malaria an opportunistic infection in HIV/AIDS patients? - A Nigerian experience

Background

HIV and malaria interact at the level of the host's susceptibility to infection, but little is known about the effect of HIV on malaria infection in Nigeria.

Objective

This study estimated the prevalence of malaria parasitaemia and its relationship with HIV immunodeficiency.

Methods

This cross-sectional study was conducted in two hospitals in Abuja, Nigeria between October 2012 and March 2013 among 600 respondents, comprising 200 HIV-negative controls, 200 HIV-positive patients on antiretroviral therapy (ART), and 200 HIV-positive patients not on ART. Malaria parasites, malaria density and absolute CD4 counts were carried out on all three groups. Participants with CD4 counts below 350 cells/mm3 were considered immunocompromised and likely to develop opportunistic infections.

Results

Most study participants were aged 21-40 years (65.2%). The mean CD4 counts of HIV-positive patients not on ART (300 ± 211 cells/mm3) and those on ART (354 cells/mm3) were significantly lower than among controls (834 cells/mm3) (p < 0.001). Malaria prevalence was not statistically different between the controls (44.5%), patients on ART (40.5%), and those not on ART (39.5%) (p = 0.562). Compared to 7% immunodeficiency among controls, 56% of patients on ART and 65.5% of those not on ART had a CD4 count < 350 cells/mm3 (p < 0.001). The prevalence of malaria parasitaemia among immunodeficient individuals (42.4%) was similar to prevalence among those with CD4 counts > 350 cells/mm3 (40.8%; p = 0.695).

Conclusion

These findings suggest that malaria parasitaemia is not an opportunistic infection among HIV-positive individuals in Nigeria.

Initiation of anti-retroviral/Trimethoprim-Sulfamethoxazole therapy in a longitudinal cohort of HIV-1 positive individuals in Western Kenya rapidly decreases asymptomatic malarial parasitemia

Interactions between malaria and HIV-1 have important public health implications. Our previous cross-sectional studies showed significant associations between HIV-1 positivity and malarial parasitemia with an increased risk of gametocytemia. In this follow-up longitudinal study, we evaluated these associations to determine the magnitude of asymptomatic parasitemia over time, and to examine the effects of initiating Antiretroviral Therapy (ART) together with the broad-spectrum antibiotic Trimethoprim Sulfamethoxazole (TS) on asymptomatic parasitemia. 300 adult volunteers in a malaria holoendemic region in Western Kenya were enrolled and followed for six months. The study groups were composed of 102 HIV-1 negatives, 106 newly diagnosed HIV-1 positives and 92 HIV-1 positives who were already stable on ART/TS. Blood samples were collected monthly and asymptomatic malarial parasitemia determined using sensitive 18S qPCR. Results showed significantly higher malaria prevalence in the HIV-1 negative group (61.4%) (p=0.0001) compared to HIV-1 positives newly diagnosed (36.5%) and those stable on treatment (31.45%). Further, treatment with ART/TS had an impact on incidence of asymptomatic parasitemia. In volunteers who were malaria PCR-negative at enrollment, the median time to detectable asymptomatic infection was shorter for HIV-1 negatives (149 days) compared to the HIV-1 positives on treatment (171 days) (p=0.00136). Initiation of HIV treatment among the newly diagnosed led to a reduction in malarial parasitemia (expressed as 18S copy numbers/μl) by over 85.8% within one week of treatment and a further reduction by 96% after 2 weeks. We observed that while the impact of ART/TS on parasitemia was long term, treatment with antimalarial Artemether/Lumefantrine (AL) among the malaria RDT positives had a transient effect with individuals getting re-infected after short periods. As was expected, HIV-1 negative individuals had normal CD4+ levels throughout the study. However, CD4+ levels among HIV-1 positives who started treatment were low at enrollment but increased significantly within the first month of treatment. From our association analysis, the decline in parasitemia among the HIV-1 positives on treatment was attributed to TS treatment and not increased CD4+ levels per se. Overall, this study highlights important interactions between HIV-1 and malaria that may inform future use of TS among HIV-infected patients in malaria endemic regions.

HIV-1 Impact on Malaria Transmission: A Complex and Relevant Global Health Concern

Malaria/HIV-1 co-infection has become a significant public health problem in the tropics where there is geographical overlap of the two diseases. It is well described that co-infection impacts clinical progression of both diseases; however, less is known about the impact of co-infection on disease transmission. Malaria transmission is dependent upon multiple critical factors, one of which is the presence and viability of the sexual-stage gametocyte. In this review, we summarize evidence surrounding gametocyte production in Plasmodium falciparum and the development factors and the consequential impact that HIV-1 has on malaria parasite transmission. Epidemiological and clinical evidence surrounding anemia, immune dysregulation, and chemotherapy as it pertains to co-infection and gametocyte transmission are reviewed. We discuss significant gaps in understanding that are often due to the biological complexities of both diseases as well as the lack of entomological data necessary to define transmission success. In particular, we highlight special epidemiological populations, such as co-infected asymptomatic gametocyte carriers, and the unique role these populations have in a future focused on malaria elimination and eradication.

Spiro-β-lactam BSS-730A Displays Potent Activity against HIV and Plasmodium

The high burden of malaria and HIV/AIDS prevents economic and social progress in developing countries. A continuing need exists for development of novel drugs and treatment regimens for both diseases in order to address the tolerability and long-term safety concerns associated with current treatment options and the emergence of drug resistance. We describe new spiro-β-lactam derivatives with potent (nM) activity against HIV and Plasmodium and no activity against bacteria and yeast. The best performing molecule of the series, BSS-730A, inhibited both HIV-1 and HIV-2 replication with an IC₅₀ of 13 ± 9.59 nM and P. berghei hepatic infection with an IC₅₀ of 0.55 ± 0.14 μM with a clear impact on parasite development. BSS-730A was also active against the erythrocytic stages of P. falciparum, with an estimated IC₅₀ of 0.43 ± 0.04 μM. Time-of-addition studies showed that BSS-730A potentially affects all stages of the HIV replicative cycle, suggesting a complex mechanism of action. BSS-730A was active against multidrug-resistant HIV isolates, with a median 2.4-fold higher IC₅₀ relative to control isolates. BSS-730A was equally active against R5 and X4 HIV isolates and displayed strong synergism with the entry inhibitor AMD3100. BSS-730A is a promising candidate for development as a potential therapeutic and/or prophylactic agent against HIV and Plasmodium.

Affinity purification of Plasmodium ookinetes from in vitro cultures using extracellular matrix gel

Malaria transmission depends on the parasites' successful invasion of the mosquito. This is achieved by the ookinete, a motile zygote that forms in the blood bolus after the mosquito takes an infectious blood meal. The ookinete invades the midgut epithelium and strongly attaches to the basal lamina, differentiating into an oocyst that produces the vertebrate-invasive sporozoites. Despite their importance, the ookinete and the oocyst are the least studied stages of the parasite. Much of what we know about the ookinete comes from in vitro experiments, which are hindered by the concomitant contamination with blood cells and other parasite stages. Although methods to purify them exist, they vary in terms of yield, costs, and difficulty to perform. A method for ookinete purification taking advantage of their adhesive properties was herein developed. The method consists of covering any culture-suitable surface with extracellular matrix gel, after which the ookinete culture is incubated on the gel to allow for ookinete attachment. The contaminant cells are then simply washed away. This procedure results in purer and less stressed ookinete preparations, which, by the nature of the method, are ready for oocyst production. Furthermore, it allows for micro-purifications using only 1 μl of blood, opening the possibility to make axenic ookinete cultures without sacrificing mice.

Repurposing Drugs to Fight Hepatic Malaria Parasites

Malaria remains one of the most prevalent infectious diseases worldwide, primarily affecting some of the most vulnerable populations around the globe. Despite achievements in the treatment of this devastating disease, there is still an urgent need for the discovery of new drugs that tackle infection by Plasmodium parasites. However, de novo drug development is a costly and time-consuming process. An alternative strategy is to evaluate the anti-plasmodial activity of compounds that are already approved for other purposes, an approach known as drug repurposing. Here, we will review efforts to assess the anti-plasmodial activity of existing drugs, with an emphasis on the obligatory and clinically silent liver stage of infection. We will also review the current knowledge on the classes of compounds that might be therapeutically relevant against Plasmodium in the context of other communicable diseases that are prevalent in regions where malaria is endemic. Repositioning existing compounds may constitute a faster solution to the current gap of prophylactic and therapeutic drugs that act on Plasmodium parasites, overall contributing to the global effort of malaria eradication.