Identifying malaria vector breeding habitats with remote sensing data and terrain-based landscape indices in Zambia

<p>Abstract</p> <p>Background</p> <p>Malaria, caused by the parasite <it>Plasmodium falciparum</it>, is a significant source of morbidity and mortality in southern Zambia. In the Mapanza Chiefdom, where transmission is seasonal, <it>Anopheles arabiensis </it>is the dominant malaria vector. The ability to predict larval habitats can help focus control measures.</p> <p>Methods</p> <p>A survey was conducted in March-April 2007, at the end of the rainy season, to identify and map locations of water pooling and the occurrence anopheline larval habitats; this was repeated in October 2007 at the end of the dry season and in March-April 2008 during the next rainy season. Logistic regression and generalized linear mixed modeling were applied to assess the predictive value of terrain-based landscape indices along with LandSat imagery to identify aquatic habitats and, especially, those with anopheline mosquito larvae.</p> <p>Results</p> <p>Approximately two hundred aquatic habitat sites were identified with 69 percent positive for anopheline mosquitoes. Nine species of anopheline mosquitoes were identified, of which, 19% were <it>An. arabiensis</it>. Terrain-based landscape indices combined with LandSat predicted sites with water, sites with anopheline mosquitoes and sites specifically with <it>An. arabiensis</it>. These models were especially successful at ruling out potential locations, but had limited ability in predicting which anopheline species inhabited aquatic sites. Terrain indices derived from 90 meter Shuttle Radar Topography Mission (SRTM) digital elevation data (DEM) were better at predicting water drainage patterns and characterizing the landscape than those derived from 30 m Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) DEM.</p> <p>Conclusions</p> <p>The low number of aquatic habitats available and the ability to locate the limited number of aquatic habitat locations for surveillance, especially those containing anopheline larvae, suggest that larval control maybe a cost-effective control measure in the fight against malaria in Zambia and other regions with seasonal transmission. This work shows that, in areas of seasonal malaria transmission, incorporating terrain-based landscape models to the planning stages of vector control allows for the exclusion of significant portions of landscape that would be unsuitable for water to accumulate and for mosquito larvae occupation. With increasing free availability of satellite imagery such as SRTM and LandSat, the development of satellite imagery-based prediction models is becoming more accessible to vector management coordinators.</p

Assessment of Peer-Based and Structural Strategies for Increasing Male Participation in an Antenatal Setting in Lilongwe, Malawi

In sub-Saharan Africa, although male involvement in antenatal care is associated with positive outcomes for HIV-infected women and their  infants, men rarely accompany female partners. We implemented a project to increase the number of male partners attending an antenatal clinic at Bwaila Hospital in Lilongwe, Malawi. We evaluated changes in the  proportion of women who came with a partner over three periods. During period 1 (January 2007 – June 2008) there was didactic peer education. During period 2 (July 2008 – September 2009) a peer-led   male-involvement drama was introduced into patient waiting areas. During period 3 (October 2009 – December 2009) changes to clinical infrastructure were introduced to make the clinic more male-friendly. The proportion of women attending ANC with a male partner increased from 0.7% to 5.7% to 10.7% over the three periods. Peer education through drama and  male-friendly hospital infrastructure coincided with substantially greater male participation, although further gains are necessary. Afr J Reprod Health 2014; 18[2]: 97-104).Keywords: HIV, antenatal, male involvement, HIV counseling and testing, disclosure, prevention of mother to child transmission, coupl

Exploring the feasibility of engaging Traditional Birth Attendants in a prevention of Mother to Child HIV Transmission program in Lilongwe, Malawi

ObjectiveTo investigate the willingness of Traditional Birth Attendants (TBAs) to provide single dose antiretroviral prophylaxis to infants born to mothers with HIV and the feasibility of providing the TBAs with antiretroviral medication.Design2 focus groups with a total of 17 registered TBAs.SettingLilongwe, MalawiMethodsTBAs were recruited by local health workers and participated in focus groups assessing their attitudes towards participation in a PMTCT program.ResultsTBAs were willing to participate in this prevention of mother-to-child HIV transmission (PMTCT) program and helped identify barriers to their participation.ConclusionsGiven appropriate support and training, TBAs’ participation in PMTCT programs could be an additional way to deliver medication to mothers and neonates who might otherwise miss crucial doses of medication

Changing individual-level risk factors for malaria with declining transmission in southern Zambia: a cross-sectional study

<p>Abstract</p> <p>Background</p> <p>Malaria elimination will require that both symptomatic- and asymptomatic-infected persons be identified and treated. However, well-characterized, individual-level risk factors for malaria may not be valid in regions with declining malaria transmission. Changes in individual-level correlates of malaria infection were evaluated over three years in a region of declining malaria transmission in southern Zambia.</p> <p>Methods</p> <p>Malaria surveys were conducted in two study areas within the catchment area of Macha Hospital, Zambia in 2007 and 2008/2009. A random sample of households was identified from a digitized satellite image of the study areas. Cross-sectional surveys were conducted approximately five times throughout the year in each of the two study areas. During study visits, adults and caretakers of children were administered questionnaires and a blood sample was obtained for a rapid diagnostic test (RDT) for malaria.</p> <p>Results</p> <p>In the 2007 study area, 330 individuals were surveyed. 40.9% of participants lived in a household with at least one insecticide-treated bed net (ITN); however, only 45.2% reported sleeping under the ITN. 23.9% of participants were RDT positive. Correlates of RDT positivity included younger age, the presence of symptoms, testing during the rainy season, using an open water source, and not sleeping under an ITN. In the 2008 study area, 435 individuals were surveyed. 77.0% of participants lived in a household with at least one ITN; however, only 56.4% reported sleeping under the ITN. 8.1% of participants were RDT positive. RDT positivity was negatively correlated with the presence of symptoms within the last two weeks but positively correlated with documented fever. In 2009, 716 individuals were surveyed in the same area as 2008. 63.7% of participants lived in a household with at least one ITN; however, only 57.7% reported sleeping under the ITN. 1.5% of participants were RDT positive. Only self-reported fever was significantly correlated with RDT positivity.</p> <p>Conclusions</p> <p>With declining malaria prevalence, few individual-level characteristics were correlated with RDT positivity. This lack of correlation with individual characteristics hampers identification of individuals infected with malaria. Strategies based on ecological or environmental risk factors may be needed to target control efforts and achieve further reductions and elimination.</p

Incorporating Acute HIV Screening into Routine HIV Testing at Sexually Transmitted Infection Clinics, and HIV Testing and Counseling Centers in Lilongwe, Malawi

Background and Objectives:Integrating acute HIV-infection (AHI) testing into clinical settings is critical to prevent transmission, and realize potential treatment-as-prevention benefits. We evaluated acceptability of AHI testing and compared AHI prevalence at sexually transmitted infection (STI) clinics and HIV testing and counseling (HTC) clinics in Lilongwe, Malawi.Methods:We conducted HIV RNA testing for HIV-seronegative patients visiting STI and HTC clinics. AHI was defined as positive RNA and negative/discordant rapid antibody tests. We evaluated demographic, behavioral, and transmission-risk differences between STI and HTC patients and assessed performance of a risk-score for targeted screening.Results:Nearly two-thirds (62.8%, 9280/14,755) of eligible patients consented to AHI testing. We identified 59 persons with AHI (prevalence = 0.64%)–a 0.9% case-identification increase. Prevalence was higher at STI [1.03% (44/4255)] than at HTC clinics [0.3% (15/5025), P < 0.01], accounting for 2.3% of new diagnoses vs 0.3% at HTC clinic. Median viral load (VL) was 758,050 copies per milliliter; 25% (15/59) had VL ≥10,000,000 copies per milliliter. Median VL was higher at STI (1,000,000 copies/mL) compared with HTC (153,125 copies/mL, P = 0.2). Among persons with AHI, those tested at STI clinics were more likely to report genital sores compared with those tested at HTC clinics (54.6% vs 6.7%, P < 0.01). The risk score algorithm performed well in identifying persons with AHI at HTC clinics (sensitivity = 73%, specificity = 89%).Conclusions:The majority of patients consented to AHI testing. AHI prevalence was substantially higher in STI clinics than HTC clinics. Remarkably high VLs and concomitant genital scores demonstrate the potential for transmission. Universal AHI screening at STI clinics, and targeted screening at HTC centers, should be considered

A method of active case detection to target reservoirs of asymptomatic malaria and gametocyte carriers in a rural area in Southern Province, Zambia

<p>Abstract</p> <p>Background</p> <p>Asymptomatic reservoirs of malaria parasites are common yet are difficult to detect, posing a problem for malaria control. If control programmes focus on mosquito control and treatment of symptomatic individuals only, malaria can quickly resurge if interventions are scaled back. Foci of parasite populations must be identified and treated. Therefore, an active case detection system that facilitates detection of asymptomatic parasitaemia and gametocyte carriers was developed and tested in the Macha region in southern Zambia.</p> <p>Methods</p> <p>Each week, nurses at participating rural health centres (RHC) communicated the number of rapid diagnostic test (RDT) positive malaria cases to a central research team. During the dry season when malaria transmission was lowest, the research team followed up each positive case reported by the RHC by a visit to the homestead. The coordinates of the location were obtained by GPS and all consenting residents completed a questionnaire and were screened for malaria using thick blood film, RDT, nested-PCR, and RT-PCR for asexual and sexual stage parasites. Persons who tested positive by RDT were treated with artemether/lumefantrine (Coartem^®). Data were compared with a community-based study of randomly selected households to assess the prevalence of asymptomatic parasitaemia in the same localities in September 2009.</p> <p>Results</p> <p>In total, 186 and 141 participants residing in 23 case and 24 control homesteads, respectively, were screened. In the case homesteads for which a control population was available (10 of the 23), household members of clinically diagnosed cases had a 8.0% prevalence of malaria using PCR compared to 0.7% PCR positive individuals in the control group (p = 0.006). The case and control groups had a gametocyte prevalence of 2.3% and 0%, respectively but the difference was not significant (p = 0.145).</p> <p>Conclusions</p> <p>This pilot project showed that active case detection is feasible and can identify reservoirs of asymptomatic infection. A larger sample size, data over multiple low transmission seasons, and in areas with different transmission dynamics are needed to further validate this approach.</p

Evaluating the benefits of incorporating traditional birth attendants in HIV Prevention of Mother to Child Transmission service delivery in Lilongwe, Malawi

The objective of our intervention was to examine the benefits of incorporating traditional birth attendants (TBA) in HIV Prevention of Mother to Child Transmission (PMTCT) service delivery. We developed a training curriculum for TBAs related to PMTCT and current TBA roles in Malawi. Fourteen TBAs and seven TBA assistants serving 4 urban health centre catchment areas were assessed, trained and supervised. Focus group discussions with the TBAs were conducted after implementation of the program. From March 2008 to August 2009, a total of 4017 pregnant women visited TBAs, out of which 2133 (53.1%) were directly referred to health facilities and 1,884 (46.9%) women delivered at TBAs and subsequently referred. 168 HIV positive women were identified by TBAs. Of these, 86/168 (51.2%) women received nevirapine and 46/168 (27.4%) HIV exposed infants received nevirapine. The challenges in providing PMTCT services included lack of transportation for referrals and absence of a reporting system to confirm the woman’s arrival at the health center. Non-disclosure of HIV status by patients to the TBAs resulted in inability to assist nevirapine uptake. TBAs, when trained and well-supervised, can supplement efforts to provide PMTCT services in communities. (Afr J Reprod Health 2014; 18[1]: 27-34).Keywords: Traditional Birth Attendants, PMTCT, Malaw

Sustained Sexual Behavior Change after Acute HIV Diagnosis in Malawi

Background Identification of acute HIV infection (AHI) allows for important opportunities for HIV prevention through behavior change and biomedical intervention. Here, we evaluate changes in sexual risk behaviors among persons with AHI enrolled in a combined behavioral and biomedical intervention designed to reduce onward transmission of HIV. Methods Participants were randomized to standard HIV counseling, a multisession behavioral intervention, or a multisession behavioral intervention plus antiretrovirals. Sexual behaviors were assessed periodically over 1 year. Results Four weeks after diagnosis, the predicted probability of reporting multiple sexual partners decreased from 24% to 9%, and the probability of reporting unprotected sex decreased from 71% to 27%. These declines in sexual risk behaviors were sustained over follow-up irrespective of study arm. Conclusions Diagnosis of AHI alone may be sufficient to achieve immediate and sustained behavior change during this highly infectious period

Human Immunodeficiency Virus (HIV)-1 Transmission among Persons with Acute HIV-1 Infection in Malawi: Demographic, Behavioral, and Phylogenetic Relationships

Background: Understanding sexual networks involving acute human immunodeficiency virus (HIV)-1 infections (AHI) may lead to prevention opportunities to mitigate high rates of onward transmission. We evaluated HIV-1 phylogenetic and behavioral characteristics among persons with AHI and their referred partners. Methods: Between 2012 and 2014, 46 persons with AHI in Malawi participated in a combined behavioral and biomedical intervention. Participants referred sexual partners by passive referral. Demographics and sexual behaviors were collected through interviews and HIV-1 genetic relationships were assessed with phylogenetics. Results: Among 45 AHI participants with HIV-1 sequences, none was phylogenetically-linked with another AHI index. There were 19 (42%) AHI participants who referred a single partner that returned for testing. Most partners (n = 17) were HIV-infected, with 15 (88%) presenting with an established infection. There were 14 index-partner pairs that had sequences available; 13 (93%) pairs were phylogenetically-linked dyads. The AHI index was female in 7/13 (54%) dyads. Age-disparate relationships among dyads were common (≥5-year age difference in 67% of dyads), including 3/6 dyads involving a male index and a younger woman. Index participants with a referred partner were more likely to report no casual partners and to be living with their current partner than participants not in dyads. Conclusions: Passive-partner referral successfully identified partners with genetically-similar HIV infections - the likely source of infection - but only 40% of index cases referred partners who presented for HIV-1 testing. Future work evaluating assisted partner notification may help reach susceptible partners or more people with untreated HIV-1 infections connected to acute transmission. Clinical Trials Registration: NCT01450189