Insecticide-treated net effectiveness at preventing Plasmodium falciparum infection varies by age and season.

BACKGROUND: After increasing coverage of malaria interventions, malaria prevalence remains high in Malawi. Previous studies focus on the impact of malaria interventions among children under 5 years old. However, in Malawi, the prevalence of infection is highest in school-aged children (SAC), ages 5 to 15 years. This study examined the interaction between age group and insecticide-treated net (ITN) use for preventing individual and community-level infection in Malawi. METHODS: Six cross-sectional surveys were conducted in the rainy and dry seasons in southern Malawi from 2012 to 2014. Data were collected on household ITN usage and demographics. Blood samples for detection of Plasmodium falciparum infection were obtained from all household members present and over 6 months of age. Generalized linear mixed models were used to account for clustering at the household and community level. RESULTS: There were 17,538 observations from six surveys. The association between ITN use and infection varied by season in SAC, but not in other age groups. The adjusted odds ratio (OR) for infection comparing ITN users to non-users among SAC in the rainy season and dry season was 0.78 (95% CI 0.56, 1.10) and 0.51 (0.35, 0.74), respectively. The effect of ITN use did not differ between children under five and adults. Among all non-SACs the OR for infection was 0.78 (0.64, 0.95) in those who used ITNs compared to those that did not. Community net use did not protect against infection. CONCLUSIONS: Protection against infection with ITN use varies by age group and season. Individual estimates of protection are moderate and a community-level effect was not detected. Additional interventions to decrease malaria prevalence are needed in Malawi.

Bed net use among school-aged children after a universal bed net campaign in Malawi.

BACKGROUND: Recent data from Malawi suggest that school-aged children (SAC), aged 5-15 years, have the highest prevalence of Plasmodium falciparum infection among all age groups. They are the least likely group to utilize insecticide-treated nets (ITNs), the most commonly available intervention to prevent malaria in Africa. This study examined the effects of a universal ITN distribution campaign, and their durability over time in SAC in Malawi. This study identified factors that influence net usage among SAC and how these factors changed over time. METHODS: Cross-sectional surveys using cluster random sampling were conducted at the end of each rainy and dry season in southern Malawi from 2012 to 2014; six surveys were done in total. Mass net distribution occurred between the first and second surveys. Data were collected on household and individual net usage as well as demographic information. Statistical analyses used generalized linear mixed models to account for clustering at the household and neighbourhood level. RESULTS: There were 7347 observations from SAC and 14,785 from young children and adults. SAC used nets significantly less frequently than the rest of the population (odds ratio (OR) from 0.14 to 0.38). The most important predictors of net usage among SAC were a lower ratio of people to nets in a household and higher proportion of nets that were hanging at the time of survey. Older SAC (11-15 years) were significantly less likely to use nets than younger SAC (5-10 years) [OR = 0.24 (95 % CI: 0.21, 0.28)]. The universal bed net campaign led to a statistically significant population-wide increase in net use, however net use returned to near baseline within 3 years. CONCLUSIONS: This study suggests that a single universal net distribution campaign, in combination with routine distribution through health clinics is not sufficient to cause a sustained increase in net usage among SAC. Novel approaches to ITN distribution, such as school-based distribution, may be needed to address the high prevalence of infection in SAC.

Effect of Plasmodium falciparum malaria on concentration of HIV-1-RNA in the blood of adults in rural Malawi: a prospective cohort study.

BACKGROUND: Raised HIV viral load in blood has been associated with accelerated disease progression and increased transmission of infection. To assess the effect of Plasmodium falciparum malaria on concentrations of HIV in blood, we did a prospective cohort study in Malawi. METHODS: We recruited 367 HIV-1-infected adults. Among 334 people aparasitaemic at baseline, 148 had at least one malaria episode during follow-up and received antimalarial treatment. Of these, 77 had HIV-1-RNA measurements at baseline, during malaria, and post-malaria. We used linear regression with generalised estimating equations to assess effect of four definitions of malaria (any parasitaemia, parasite density > or =2000/microL, febrile parasitaemia, and febrile parasitaemia with parasite density > or =2000/microl) on changes in log HIV-1 RNA, overall and by baseline CD4 count. FINDINGS: With malaria defined as any parasitaemia, HIV-1-RNA concentration almost doubled between baseline (median 96215 copies per mL) and malaria (168901 copies per mL), a 0.25 (95% CI 0.11-0.39) log increase in mean RNA concentration. HIV-1-RNA concentration fell to median 82058 copies per mL by about 8-9 weeks post-malaria. Increases in HIV-1-RNA were greatest for people with fever, parasite density 2000/microL or greater, and CD4 count more than 300 cells per muL, in whom concentrations rose from median 38483 copies per mL at baseline to 196098 copies per mL during malaria, a mean log increase of 0.82 (95% CI 0.55-1.10, p<0.0001), and fell to median 75331 copies per mL post-malaria. People who remained aparasitaemic showed no changes in HIV-1-RNA concentration. INTERPRETATION: HIV-infected individuals with malaria have a significantly increased viral load, which might enhance HIV transmission and accelerate disease progression.

Pneumocystis pneumonia in HIV-positive adults, Malawi.

In a prospective study of 660 HIV-positive Malawian adults, we diagnosed Pneumocystis jirovecii pneumonia (PcP) using clinical features, induced sputum for immunofluorescent staining, real-time PCR, and posttreatment follow-up. PcP incidence was highest in patients with the lowest CD4 counts, but PcP is uncommon compared with incidences of pulmonary tuberculosis and bacterial pneumonia.

A community-based study of the incidence of trimethoprim-sulfamethoxazole-preventable infections in Malawian adults living with HIV.

The benefits of trimethoprim-sulfamethoxazole (TS) prophylaxis reported for persons living with HIV in Cote d'Ivoire are difficult to extrapolate to sub-Saharan African countries where bacterial resistance to TS is higher and cross-resistance between TS and sulfadoxine-pyrimethamine (SP) may impair SP efficacy for malaria treatment. We conducted a community-based cohort study to measure the incidence of potentially TS-preventable illnesses in Blantyre, Malawi. We found a high incidence of malaria, invasive bacterial infections, and probable bacterial pneumonias but low rates of Pneumocystis jiroveci pneumonia, isosporiasis, and Toxoplasma encephalitis. Most bacterial isolates were resistant to TS but sensitive to azithromycin, a possible alternative to TS. Clinical trials are needed to determine the role of TS or alternative regimens for prophylaxis against secondary infections among people living with HIV in sub-Saharan Africa. These should also assess benefit in patients receiving antiretroviral therapy.