A Comparative analysis of PESC and PPSC copolyesters: Insights into viscosity, thermal behavior, crystallinity, and biodegradability.

The study examined various properties of synthesized copolyesters PESC and PPSC. Inherent viscosities of the copolyesters, measured in 1,4-dioxane at 32 °C, were 0.65 dL/g for PESC and 0.73 dL/g for PPSC. Fourier-Transform Infrared Spectroscopy (FT-IR) revealed distinct absorption bands associated with ester carbonyl stretching, C-H bending vibration, C-H group symmetry stretching, and C-O stretching vibrations. 1H and 13C Nuclear magnetic Resonance (NMR) spectroscopy were used to identify specific protons and carbon groups in the polymer chain, revealing the molecular structure of the copolyesters. Differential Scanning Calorimetry (DSC) identified the glass transition, melting, and decomposition temperatures for both copolyesters, indicating variations in the crystalline nature of the copolymers. XRD Spectral studies further elaborated on the crystalline nature, indicating that PPSC is less amorphous than PESC. Biodegradation analysis showed that PESC degrades more quickly than PPSC, with degradation decreasing as the number of methylene groups increase. Scanning Electron Microscopy (SEM) images depicted the surface morphology of the copolyesters before and after degradation, revealing a more roughened surface with pits post-degradation. These findings provide comprehensive insights into the structural and degradable properties of PESC and PPSC copolyesters.

Ultrasonic assisted synthesis of RGO supported HoVO4-ZnO nanocomposites, their enhanced photocatalytic activities and Rhodamine B degradation.

The RGO-supported HoVO4-ZnO nanocomposite was synthesized using the ultra sonication process. X-ray diffraction patterns, Field emission scanning electron microscopy, high resolution transmission electron microscopy, Diffractive Reflectance spectroscopy, and photoluminescence spectroscopy were employed to examine the heterostructured photocatalyst in this research study. The photocatalytic efficiency of the RGO-supported HoVO4-ZnO nanoparticles, under UV light irradiation, in the degradation of Rhodamine-B dye was investigated. Undoped ZnO, bare HoVO4, and HoVO4 -ZnO, degraded at 55.6, 57.5, and 74.33 percent in 45 min, respectively. This new RGO coupled HoVO4-ZnO exhibits enhanced photocatalytic efficiency compared to the bare ZnO and HoVO4-ZnO nanocomposite.

Effectiveness of ChAdOx1 nCoV-19 Corona Virus Vaccine (CovishieldTM) in preventing SARS-CoV2 infection, Chennai, Tamil Nadu, India, 2021

BackgroundIndia experienced the second wave of the COVID-19 pandemic in March 2021, driven by the delta variant. Apprehensions around the usefulness of vaccines against delta variant posed a risk to the vaccination program. Therefore, we estimated the effectiveness of two doses of the ChAdOx1 nCoV-19 (Covishield) vaccine against COVID-19 infection among individuals [≥]45 years in Chennai, India. MethodsA community-based cohort study was conducted from May to September 2021 in a selected geographic area in Chennai, Tamil Nadu. The estimated sample size was 10,232. We enumerated individuals from all eligible households and periodically updated vaccination and COVID-19 infection data. We computed vaccine effectiveness with its 95% confidence interval for two doses of the Covishield vaccine against any COVID-19 infection. ResultsWe enrolled 69,435 individuals, of which 21,793 were above 45 years. Two dose coverage of Covishield in the 18+ and 45+ age group was 18% and 31%, respectively. The overall incidence of COVID-19 infection was 1099 per 100,000 population. The vaccine effectiveness against COVID-19 disease in the [≥]45 age group was 61.3% (95% CI: 43.6 - 73.4) at least two weeks after receiving the second dose of Covishield. Genomic analysis of 74 (28 with two doses, 15 with one dose, and 31 with zero dose) out of the 90 aliquots collected from the 303 COVID-19 positive individuals in the 45+ age group showed delta variants and their sub-lineages. ConclusionWe demonstrated the effectiveness of two doses of the ChAdOx1 vaccine against the delta variant in the general population of Chennai. We recommend similar future studies considering emerging variants and newer vaccines. Two-dose vaccine coverage could be ensured to protect against COVID-19 infection.

Exposure to mosquito coil and biomass fuel smoke and respiratory health in rural Tamil Nadu, India.

BACKGROUND: Mosquito coil smoke, along with biomass fuel smoke, are sources of indoor air pollution. Biomass fuel smoke has been studied as a risk factor for poor respiratory outcomes. However, in an Indian context, few studies examine the effect of mosquito coil exposure on poor respiratory outcomes at the community level. OBJECTIVES: To estimate the prevalence of the biomass fuel and mosquito coil use and to determine the association between the use of bio-mass fuel and mosquito coil and poor respiratory health. METHODS: A cross-sectional survey of 4662 individuals (above the age of 30 years) was conducted using a pre-tested questionnaire. Trained interviewers collected data on current and past use of biomass fuels and mosquito coils, usage practices and respiratory health. We computed proportions for exposure variables namely biomass fuel, mosquito coil use and other covariates. We conducted univariate analysis, followed by multivariate logistic regression. RESULTS: The prevalence of ever use of biomass fuels was high (wood: 97.9%; cow dung cake: 76.0% and crop residue: 54.4%). Current use of wood, cow dung cake and crop residue was prevalent among 75.7, 24.3 and 30.9% respondents, respectively. Almost 70% of respondents had ever used mosquito coils, whereas 54% were current users. Overall, 5.5% respondents had poor respiratory health either due to chronic bronchitis or asthma. In multivariate analysis, use of combination of all three biomass fuel types (adjusted odds ratio [AOR] 1.69, 95% confidence interval [CI]: 1.13-2.54) and use of mosquito coil more than or equal to 5 days per week (AOR 1.43, 95% CI: 1.04-1.99) were associated with poor respiratory health after adjusting for covariates age, gender, smoking, kitchen type and for each other. CONCLUSIONS: Use of biomass fuels and mosquito coils was high in the study population and was associated with poor respiratory health. Therefore, mosquito coil smoke should also be considered an important source of indoor air pollution, similar to biomass fuel exposure. Community education about these sources of indoor air pollution and increased coverage of cleaner fuels and alternative mosquito control methods should be the way forward in the rural areas.

Seroprevalence of Dengue Infection Using IgG Capture ELISA in India, 2017-2018.

We conducted a nationally representative population-based survey in 60 districts from 15 Indian states covering all five geographic regions during 2017-2018 to estimate the age specific seroprevalence of dengue. Of the 12,300 sera collected, 4,955 were positive for IgG antibodies against dengue virus using IgG Indirect ELISA indicating past dengue infection. We tested 4,948 sera (seven had inadequate volume) positive for IgG antibodies on indirect ELISA using anti-dengue IgG capture ELISA to estimate the proportion of dengue infections with high antibody titers, suggestive of acute or recent secondary infection. Of the 4,948 sera tested, 529 (10.7%; 95% CI: 9.4-12.1) were seropositive on IgG capture ELISA. The proportions of dengue infections with high titers were 1.1% in the northeastern, 1.5% in the eastern, 6.2% in the western, 12.2% in the southern, and 16.7% in the northern region. The distribution of dengue infections varied across geographic regions, with a higher proportion of infections with high antibody titer in the northern and southern regions of India. The study findings could be useful for planning facilities for clinical management of dengue infections.

Seroprevalence of Rickettsial Infections in Northeast India: A Population-Based Cross-Sectional Survey.

A cross-sectional survey was undertaken to estimate seroprevalence of immunoglobulin G antibodies against scrub typhus, spotted fever group rickettsiae, and typhus group rickettsiae in randomly selected 48 clusters in 12 districts of 3 Northeast states of India: Assam, Meghalaya, and Tripura. Individuals in 3 age groups (5-8, 9-17, and 18-45 years) were selected from each cluster. Sera (N = 2360) tested were collected as part of a national survey on dengue seroprevalence conducted between September 2017 and February 2018. Overall, seroprevalence of 2.5% was detected against rickettsioses, with highest positivity against spotted fever group rickettsiae, followed by scrub typhus and typhus group rickettsiae. Seroprevalence was highest in Tripura (3.7%), followed by Assam (2.6%) and Meghalaya (1.04%). Adults of 18 to 45 years of age were found to be most affected (3.8%). The study findings indicate the need for increasing testing facilities for active case detection at hospital levels. Efforts on implementing effective preventing strategies are suggested to be targeted in disease-specific endemic foci.

Hepatitis-B virus infection in India: Findings from a nationally representative serosurvey, 2017-18.

INTRODUCTION: India introduced a hepatitis-B (HB) vaccine in the Universal Immunization Program in 2002-2003 on a pilot basis, expanded to ten states in 2007-2008 (phase-1), and the entire country in 2011-2012 (phase-2). We tested sera from a nationally representative serosurvey conducted duing 2017, to estimate the seroprevalence of different markers of HB infection among children aged 5-17 years in India and to assess the impact of vaccination. METHODS: We tested sera from 8273 children for different markers of HB infection and estimated weighted age-group specific seroprevalence of children who were chronically infected (HBsAg and anti-HBc positive), and immune due to past infection (anti-HBc positive and HBsAg negative), and having serological evidence of HB vaccination (only anti-HBs positive). We compared the prevalence of serological markers among children born before (aged 11-17 years) and after (aged 5-10 years) introduction of HB-vaccine from phase-1 states. RESULTS: Among children aged 5-8 years, 1.1% were chronic carriers, 5.3% immune due to past infection, and 23.2% vaccinated. The corresponding proportions among children aged 9-17 years were 1.1%, 8.0%, and 12.0%, respectively. In phase-1 states, children aged 5-10 years had a significantly lower prevalence of anti-HBc (4.9% vs. 7.6%, p<0.001) and higher prevalence of anti-HBs (37.7% vs. 14.7%, p<0.001) compared to children aged 11-17 years. HBsAg positivity, however, was not different in the two age groups. CONCLUSIONS: Children born after the introduction of HB vaccination had a lower prevalence of past HBV infection and a higher prevalence of anti-HBs. The findings of our study could be considered as an interim assessment of the impact of the hepatitis B vaccine introduction in India.

Does the morbidity management and disability prevention (MMDP) clinic serve the filarial lymphedema (FLE) patients' preeminent expectation?

Advocacy and training on "Home care" for filarial lymphoedma (FLE) patients are provided through morbidity management and disability prevention (MMDP) clinic commonly known as filariasis clinic and clinical improvement is assessed by follow-up visits. While the physicians aim at reducing the recurrent ADL (coined as ADLA in 1997) episodes, the patients expect reduction in LE volume. The objective of the present study was to know whether the MMDP clinic serves the primary expectation of the FLE patients. LE patients who attended the clinic for at least four follow-up consultations and had LE volume measurements at three points of time during the one year period of observation were considered for analysis. Clinical assessment was done for LE grading and LE volume was measured by water displacement volumetry. Sixty-three patients who fulfilled the follow up criteria were included. It was observed that the median LE volume was 914ml (IQR 269 - 1935) at first visit of the observation period which reduced to 645ml (IQR 215- 1666) and 752ml (IQR 215 - 1720) at first and second follow-up visits respectively. Over all, in short span of one year, 21 of the 63 patients (33.3%) who visited MMDP clinic at least four times in a year were benefitted through the MMDP advocacy and the National filariasis control programme need to emphasise on the importance of follow up visits to FLE patients.

Does the morbidity management and disability prevention (MMDP) clinic serve the filarial lymphedema (FLE) patients’ preeminent expectation?

@#Advocacy and training on “Home care” for filarial lymphoedma (FLE) patients are provided through morbidity management and disability prevention (MMDP) clinic commonly known as filariasis clinic and clinical improvement is assessed by follow-up visits. While the physicians aim at reducing the recurrent ADL (coined as ADLA in 1997) episodes, the patients expect reduction in LE volume. The objective of the present study was to know whether the MMDP clinic serves the primary expectation of the FLE patients. LE patients who attended the clinic for at least four follow-up consultations and had LE volume measurements at three points of time during the one year period of observation were considered for analysis. Clinical assessment was done for LE grading and LE volume was measured by water displacement volumetry. Sixty-three patients who fulfilled the follow up criteria were included. It was observed that the median LE volume was 914ml (IQR 269 – 1935) at first visit of the observation period which reduced to 645ml (IQR 2151666) and 752ml (IQR 215 – 1720) at first and second follow-up visits respectively. Over all, in short span of one year, 21 of the 63 patients (33.3%) who visited MMDP clinic at least four times in a year were benefitted through the MMDP advocacy and the National filariasis control programme need to emphasise on the importance of follow up visits to FLE patients.

Burden of dengue infection in India, 2017: a cross-sectional population based serosurvey.

BACKGROUND: The burden of dengue virus (DENV) infection across geographical regions of India is poorly quantified. We estimated the age-specific seroprevalence, force of infection, and number of infections in India. METHODS: We did a community-based survey in 240 clusters (118 rural, 122 urban), selected from 60 districts of 15 Indian states from five geographical regions. We enumerated each cluster, randomly selected (with an Andriod application developed specifically for the survey) 25 individuals from age groups of 5-8 years, 9-17 years, and 18-45 years, and sampled a minimum of 11 individuals from each age group (all the 25 randomly selected individuals in each age group were visited in their houses and individuals who consented for the survey were included in the study). Age was the only inclusion criterion; for the purpose of enumeration, individuals residing in the household for more than 6 months were included. Sera were tested centrally by a laboratory team of scientific and technical staff for IgG antibodies against the DENV with the use of indirect ELISA. We calculated age group specific seroprevalence and constructed catalytic models to estimate force of infection. FINDINGS: From June 19, 2017, to April 12, 2018, we randomly selected 17 930 individuals from three age groups. Of these, blood samples were collected and tested for 12 300 individuals (5-8 years, n=4059; 9-17 years, n=4265; 18-45 years, n=3976). The overall seroprevalence of DENV infection in India was 48·7% (95% CI 43·5-54·0), increasing from 28·3% (21·5-36·2) among children aged 5-8 years to 41·0% (32·4-50·1) among children aged 9-17 years and 56·2% (49·0-63·1) among individuals aged between 18-45 years. The seroprevalence was high in the southern (76·9% [69·1-83·2]), western (62·3% [55·3-68·8]), and northern (60·3% [49·3-70·5]) regions. The estimated number of primary DENV infections with the constant force of infection model was 12 991 357 (12 825 128-13 130 258) and for the age-dependent force of infection model was 8 655 425 (7 243 630-9 545 052) among individuals aged 5-45 years from 30 Indian states in 2017. INTERPRETATION: The burden of dengue infection in India was heterogeneous, with evidence of high transmission in northern, western, and southern regions. The survey findings will be useful in making informed decisions about introduction of upcoming dengue vaccines in India. FUNDING: Indian Council of Medical Research.

High prevalence of soil-transmitted helminth infections among primary school children, Uttar Pradesh, India, 2015.

BACKGROUND: Soil-transmitted helminth (STH) infections often affect the poorest and most deprived communities. In order to generate reliable data for planning a school based deworming program, we conducted a survey among primary school children studying in government schools in the Indian state of Uttar Pradesh. The objectives of our survey were to estimate the prevalence and intensity of STH infections. METHODS: We conducted a cross-sectional survey among children studying in 130 primary schools from 9 agro-climatic zones, during May - August 2015. Information about socio-demographic details, defecation and hand-hygiene practices, and stool samples were collected from the school children. Stool samples were examined using the Kato-Katz method. RESULTS: Stool samples from 6421 school children were examined. The overall weighted prevalence of any STH in the State was 75.6% (95% CI: 71.2-79.5). The prevalence was more than 50% in six of the nine agro-climatic zones. A. lumbricoides was the most prevalent STH (prevalence: 69.6%), followed by hookworm (prevalence: 22.6%) and T. trichura (4.6%). The majority of the STH infections were of low intensity. The practice of open defecation and not washing hands with soap after defecation and residence in kutcha house were significant risk factors of STH infection. CONCLUSIONS: STH prevalence among primary school children in Uttar Pradesh was high. Given the WHO guidelines on deworming frequency according to STH prevalence, Govt of Uttar Pradesh needs to implement a school-based deworming program with bi-annual frequency. The findings of our survey would also help monitor the performance of school based deworming programme.

Coverage of childhood vaccination among children aged 12-23 months, Tamil Nadu, 2015, India.

BACKGROUND & OBJECTIVES: District-Level Household Survey-4 (DLHS-4) indicated that during 2012-2013, only 56 per cent of children aged 12-23 months in Tamil Nadu were fully vaccinated, which were lesser than those reported in earlier national surveys. We, therefore, conducted cluster surveys to estimate coverage of childhood vaccination in the State, and also to identify the factors associated with low coverage. METHODS: Cross-sectional surveys were conducted in 15 strata [municipal corporation non-slum (n=1), municipal corporation slum (n=1), hilly (n=1), rural (n=6) and urban (n=6)]. From each stratum, 30 clusters were selected using probability proportional to the population size linear systematic sampling; seven children aged 12-23 months were selected from each cluster and their mothers/care-takers were interviewed to collect information about vaccination status of the child. A child was considered fully vaccinated if he/she received bacillus Calmette-Guérin (BCG), three doses of pentavalent, three doses of oral polio vaccine and one dose of measles vaccine, and appropriately vaccinated if all vaccine doses were given at right age and with right interval. Further, coverage of fully vaccinated children (FVC) as per vaccination cards or mothers' recall, validated coverage of FVC (V-FVC) among those having cards, and coverage of appropriately vaccinated children (AVC) were estimated using survey data analysis module with appropriate sampling weights. RESULTS: A total of 3150 children were surveyed, of them 2528 (80.3%) had vaccination card. The weighted coverage of FVC, V-FVC and AVC in the State was 79.9 per cent [95% confidence interval (CI): 78.2-81.5], 78.8 per cent (95% CI: 76.9-80.5) and 69.7 per cent (95% CI: 67.7-71.7), respectively. The coverage of individual vaccine ranged between 84 per cent (measles) and 99.8 per cent (BCG). About 12 per cent V-FVC were not vaccinated as per the vaccination schedule. INTERPRETATION & CONCLUSIONS: The coverage of FVC in Tamil Nadu was high, with about 80 per cent children completing primary vaccination. Efforts to increase vaccination coverage in the State need to focus on educating vaccinators about the need to adhere to the national vaccination schedule and strengthening supervision to ensure that children are vaccinated appropriately.

DNA nanostructures based biosensor for the determination of aromatic compounds.

Graphite electrode was modified using multi-walled carbon nanotubes (MWCNT), chitosan (CS), glutaraldehyde (GTA) and DNA nanostructures (nsDNA). DNA nanostructures of 50 nm in size were produced from single DNA template sequence using a simple two step procedure and were confirmed using TEM and AFM analysis. The modified electrode was applied to the electrochemical detection of aromatic compounds using EIS. The modified electrode was characterized using differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). For comparison, electrochemical results derived from single stranded (50 bp length) and double stranded (50 bp length) DNA based biosensors were used. The results indicate that the modified electrode prior to nsDNA immobilization provides a viable platform that effectively promotes electron transfer between nsDNA and the electrode. The mode of binding between the nsDNA and aromatic compounds was investigated using EIS, indicating that the dominant interaction is non-covalent. nsDNA based biosensor was observed to act as an efficient biosensor in selective and sensitive identification of aromatic compounds.

Vermicomposting of Solid Waste Using Local and Exotic Earthworms: A Comparative Study.

The aim of this study was to assess the decomposition efficiency of earthworms, local (L.mauritii) as well as exotic (Eisenia foetida) in vermicomposting of garden litter in SRM University campus. The vermicompost produced through vermicomposting of garden litter mixed with cow dung in the ratio of 3:1 by using local and exotic earthworms (Eisenia foetida) was rich in ammoniacal nitrogen, nitrate nitrogen, available phosphorus, total potassium and TKN, and there was a reduction in total organic carbon and carbon to nitrogen ratio. The study reveals that the decomposition efficiency of exotic earthworms is better compared to local earthworms.

Nonisothermal kinetics analysis of the dehydration of ziprasidone hydrochloride monohydrate by thermogravimetry.

In the current work the kinetics of dehydration of ziprasidone hydrochloride monohydrate was studied by nonisothermal thermogravimetry. Ziprasidone hydrochloride monohydrate was heated from 30 to 150° with a heating rate of 5° per min under nitrogen gas atmosphere and weight loss data were collected. Powder X-ray difraction was used to characterize the solid before and after dehydration. The well accepted Coats-Redfern model fitting approach was applied to the thermogravimetry data for the kinetic analysis. Thirteen solid state reaction models were studied; among them one-dimensional diffusion model was found to be the best fit model for this reaction with an excellent correlation 0.9994. The Arrhenius parameters, activation energy, and pre-exponential factor were determined, the values were found to be 28 k.cal/mol and 9.53×10(13) sec(-1), respectively.

Cathodic behaviour of stainless steel in coastal Indian seawater: calcareous deposits overwhelm biofilms.

Type-316 stainless steel (SS) was investigated as the cathode in galvanic couples in full-strength seawater from the Gulf of Mannar on the southeast coast of India. Tests were devised to examine the impact of SS cathodes on anode materials with or without the accrual of marine biofilms. Biofilmed SS cathodes significantly enhanced the rate of corrosion of nickel, causing noble shifts in the couple potentials. With mild steel and zinc as the anodes, calcareous deposits developed quite rapidly on the SS cathodes and led to a significant reduction of bacterial numbers. The calcareous deposits also caused substantial reduction of galvanic corrosion rates for mild steel, whereas there was no difference for zinc. The deposits were identified by XRD as essentially carbonates, oxides and hydroxides of calcium and magnesium. Potentiodynamic polarization performed on the actual couples after disconnection and equilibration provided reasonable interpretations of the galvanic corrosion trends. Data from this work suggest that a potential of about -0.70 V vs. saturated calomel electrode (SCE) should provide optimum protection of SS in warmer, full-strength seawater that supports the precipitation of calcareous deposits. The criterion commonly recommended for temperate conditions of lower water temperature and estuarine waters of lower alkalinity is -1.0 V (SCE).

Influence of recall period on estimates of diarrhoea morbidity in infants in rural Tamilnadu.

Data collected on 689 infants, in a study to assess the incidence of diarrhoea and acute respiratory infections during infancy, is used here to quantify the extent of under-reporting in diarrhoea morbidity surveys. The study area consisted of two contiguous primary health centres in Villupuram health unit district in Tamil Nadu, South India. Each day of infancy was assigned a recal period and proportion of diarrhoeal days for various recall period computed. The proportion of diarrhoea was 11.3%, 12.0% and 11.2% for zero, one and two days of recall period, respectively, after which the proportion decreased. The under-reporting of diarrhoea was approximately 15%, 26% and 45% with three, six and 7-13 days of recall period, respectively. As there is considerable under-reporting of diarrhoea morbidity when recall period exceeds three days, it would be best to collect information on diarrhoea at least twice a week in diarrhoeal morbidity surveys.

Influence of recall period on estimates of diarrhoea morbidity in infants in rural Tamil Nadu.

Data collected on 689 infants, in a study to assess the incidence of diarrhoea during infancy, is used here to quantify the extent of under-reporting in diarrhoea morbidity surveys. The study area consisted of two contiguous primary health centres in Villupuram health unit district in Tamil Nadu, south India. Each day of infancy was assigned a recall period and proportion of diarrhoeal days for various recall period computed. The proportion of diarrhoea was 11.3%, 12.0% and 11.2% for zero, one and two days of recall period, respectively, (mean 11.5%) after which the proportion decreased. The under-reporting of diarrhoea was approximately 15%, 26% and 45% with three, six and 7-13 days of recall period, respectively compared to mean. As there is considerable under-reporting of diarrhoea morbidity when recall period exceeds three days, it would be better to collect information on diarrhoea twice a week in diarrhoeal morbidity surveys.

PIP: Diarrhea morbidity is an indicator commonly used to assess the health status of young children and to measure the impact of a number of health-related interventions. In longitudinal studies, information is usually collected orally anywhere from daily to every few weeks. However, as the recall period lengthens, the likelihood increases that episodes of diarrhea will be forgotten and subsequently not reported, leading to overall underestimates of diarrhea incidence. Data collected on 689 infants in a 1991-93 study of vitamin A supplementation in mothers and infants were used to quantify the extent of under-reporting in diarrhea morbidity surveys in 2 contiguous primary health centers in Villupuram health unit district in Tamil Nadu, India. Each day of infancy was assigned a recall period and proportion of diarrheal days for the various recall period computed. The proportion of diarrhea was 11.3%, 12.0%, and 11.2% for 0, 1, and 2 days of recall period, respectively, after which the proportion decreased. The under-reporting of diarrhea was approximately 15%, 26%, and 45% with 3, 6, and 7-13 days of recall, respectively, compared to the mean. Given the high degree of under-reporting of diarrhea morbidity when the recall period exceeds 3 days, it is better to collect data on diarrhea twice a week in diarrheal morbidity surveys.