SARS-CoV-2 prevalence and immunity: a hospital-based study from Malawi.

BACKGROUND: COVID-19 transmission and disease dynamics in sub-Saharan Africa are not well understood. Our study aims to provide insight into COVID-19 epidemiology in Malawi by estimating SARS-CoV-2 prevalence and immunity after SARS-CoV-2 infection in a hospital-based setting. METHODS: We conducted a hospital-based, convenience sampling, cross-sectional survey for SARS-CoV-2 in Lilongwe, Malawi. Participants answered a questionnaire and were tested for SARS-CoV-2 by enzyme-linked immunosorbent assay and real-time reverse-transcription polymerase chain reaction (RT-PCR). A surrogate virus neutralization test (sVNT) was performed in seropositive samples to estimate immunity. Poisson regression was used to assess SARS-CoV-2 point prevalence association with demographic and behavioral variables. FINDINGS: The study included 930 participants. We found a combined point prevalence of 10.1%. Separately analyzed, RT-PCR positivity was 2.0%, and seropositivity was 9.3%. Of tested seropositive samples, 90.1% were sVNT positive. We found a high rate (45.7%) of asymptomatic SARS-CoV-2 infection. SARS-CoV-2 point prevalence was significantly associated with being a healthcare worker. INTERPRETATION: Our study suggests that official data underestimate COVID-19 transmission. Using sVNTs to estimate immunity in Malawi is feasible and revealed considerable post-infection immunity in our cohort. Subclinical infection and transmission are probably a game-changer in surveillance, mitigation and vaccination strategies.

Effect of low-level laser irradiation and epidermal growth factor on adult human adipose-derived stem cells.

The study investigated the effects of low-level laser radiation and epidermal growth factor (EGF) on adult adipose-derived stem cells (ADSCs) isolated from human adipose tissue. Isolated cells were cultured to semi-confluence, and the monolayers of ADSCs were exposed to low-level laser at 5 J/cm(2) using 636 nm diode laser. Cell viability and proliferation were monitored using adenosine triphosphate (ATP) luminescence and optical density at 0 h, 24 h and 48 h after irradiation. Application of low-level laser irradiation at 5 J/cm(2) on human ADSCs cultured with EGF increased the viability and proliferation of these cells. The results indicate that low-level laser irradiation in combination with EGF enhances the proliferation and maintenance of ADSCs in vitro.

The effect of low level laser irradiation on adult human adipose derived stem cells.

This study investigated the effect of low level laser irradiation on primary cultures of adult human adipose derived stem cells (ADSC) using a 635-nm diode laser, at 5 J/cm(2) with a power output of 50.2 mW and a power density of 5.5 mW/cm(2). Cellular morphology did not appear to change after irradiation. Using the trypan blue exclusion test, the cellular viability of irradiated cells increased by 1% at 24 h and 1.6% at 48 h but was not statistically significant. However, the increase of cellular viability as measured by ATP luminescence was statistically significant at 48 h (p < 0.05). Proliferation of irradiated cells, measured by optical density, resulted in statistically significant increases in values compared to nonirradiated cells (p < 0.05) at both time points. Western blot analysis and immunocytochemical labeling indicated an increase in the expression of stem cell marker beta1-integrin after irradiation. These results indicate that 5 J/cm(2) of laser irradiation can positively affect human adipose stem cells by increasing cellular viability, proliferation, and expression of beta1-integrin.

An audit of HIV testing and HIV serostatus in tuberculosis patients, Blantyre, Malawi.

SETTING: Queen Elizabeth Central Hospital, Blantyre, Malawi. OBJECTIVE: An audit of voluntary HIV testing, with pre- and post-test counselling, of adult patients diagnosed with all types of tuberculosis. DESIGN: A review of case files of adult patients with tuberculosis registered with the District Tuberculosis Officer, Blantyre, between April 1993 and March 1994. RESULTS: There were 1095 tuberculosis patients, mean age 32 years, of whom 665 (60.7%) had HIV-serological testing. 496 patients (74.6% of those tested) were HIV seropositive. 73% of patients who were hospitalized for the initial intensive phase of treatment were HIV-tested compared with 37% of patients who received ambulatory chemotherapy (P < 0.001). In patients HIV-tested, 5 did not wish to know their results and post-test counselling was done in 516 (78%). 23 patients refused HIV testing. 362 (84%) patients not HIV-tested never received pre-test counselling. Of 664 patients who received 2SRHZ/6HT(E) in hospital, 84 (12.6%) patients died and 8 (1.2%) absconded. The abscondee rate was unrelated to HIV serostatus. CONCLUSION: A large proportion of tuberculosis patients who receive supervised treatment in hospital accept confidential HIV testing and the abscondee rate is low. The clinical management of patients is improved.

The changing pattern of mortality in an African medical ward.

The pattern of adult medical deaths in Queen Elizabeth Central Hospital, Blantyre, Malawi was documented over a 12 month period between April 1992 and March 1993. Results were compared with mortality data collected from the same wards in the pre-AIDS era in 1973. Tuberculosis and AIDS together accounted for 49% of all medical deaths in 1992-93. Eighty-two per cent of deaths occurred in the age group 13-49 years; tuberculosis, AIDS, gastroenteritis, pneumonia, pyogenic meningitis and septicaemia were the most important causes of death in these young patients. These findings are very different to those observed in the same wards 20 years previously when tuberculosis was responsible for 13% of deaths and there were no deaths due to AIDS. The predicted upsurge in AIDS-related deaths in sub-Saharan Africa in the 1990s will have grave consequences not only for the health sector, but for the social and economic fabric of the countries concerned.

PIP: There is considerable mortality in sub-Saharan Africa relative to other regions in the world. No country in Africa, however, has a system of vital registration capable of providing reliable national data on mortality. Accurate information on the causes of adult mortality is therefore very limited. This lack of knowledge is becoming especially important in light of the impact HIV infection and AIDS are having in many sub-Saharan African countries. The authors documented the pattern of adult medical deaths in Queen Elizabeth Central Hospital, Blantyre, Malawi between April 1992 and March 1993. Their findings were then compared with data on mortality collected from the same wards in 1973, before the AIDS pandemic. Tuberculosis (TB) and AIDS together accounted for 49% of all medical deaths in 1992-93, with 82% of deaths occurring among individuals aged 13-49 years. TB, AIDS, gastroenteritis, pneumonia, pyogenic meningitis, and septicemia were the most important causes of death. In 1973, TB was responsible for 13% of deaths and there were no deaths due to AIDS. The authors note that the predicted upsurge in the level of AIDS-related mortality in sub-Saharan Africa during the 1990s will have grave consequences for the health sector, as well as for the social and economic fabric of the countries concerned.