OUP accepted manuscript

Background

The International Trachoma Initiative (ITI) provides azithromycin for mass drug administration (MDA) to eliminate trachoma as a public health problem. Azithromycin is given as tablets for adults and powder for oral suspension (POS) is recommended for children aged <7 y, children <120 cm in height (regardless of age) or anyone who reports difficulty in swallowing tablets. An observational assessment of MDA for trachoma was conducted to determine the frequency with which children aged 6 mo through 14 y received the recommended dose and form of azithromycin according to current dosing guidelines and to assess risk factors for choking and adverse swallowing events (ASEs).

Methods

MDA was observed in three regions of Ethiopia and data were collected on azithromycin administration and ASEs.

Results

A total of 6477 azithromycin administrations were observed; 97.9% of children received the exact recommended dose. Of children aged 6 mo to <7 y or <120 cm in height, 99.6% received POS. One child experienced choking and 132 (2%) experienced ≥1 ASEs. Factors significantly associated with ASEs included age 6–11 mo or 1–6 y, non-calm demeanor and requiring coaxing prior to drug administration.

Conclusions

There is a high level of adherence to the revised azithromycin dosing guidelines and low incidence of choking and ASEs.

Progress to Eliminate Trachoma as a Public Health Problem in Amhara National Regional State, Ethiopia: Results of 152 Population-Based Surveys

At baseline in 2006, Amhara National Regional State, Ethiopia, was the most trachoma-endemic region in the country. Trachoma impact surveys (TIS) were conducted in all districts between 2010 and 2015, following 3–5 years of intervention with the WHO-recommended SAFE (surgery, antibiotics, facial cleanliness, and environmental improvement) strategy. A multistage cluster random sampling design was used to estimate the district-level prevalence of trachoma. In total, 1,887 clusters in 152 districts were surveyed, from which 208,265 individuals from 66,089 households were examined for clinical signs of trachoma. The regional prevalence of trachomatous inflammation-follicular (TF) and trachomatous inflammation-intense among children aged 1–9 years was 25.9% (95% CI: 24.9–26.9) and 5.5% (95% CI: 5.2–6.0), respectively. The prevalence of trachomatous scarring and trachomatous trichiasis among adults aged ≥ 15 years was 12.9% (95% CI: 12.2–13.6) and 3.9% (95% CI: 3.7–4.1), respectively. Among children aged 1–9 years, 76.5% (95% CI: 75.3–77.7) presented with a clean face; 66.2% (95% CI: 64.1–68.2) of households had access to water within 30 minutes round-trip, 48.1% (95% CI: 45.5–50.6) used an improved water source, and 46.2% (95% CI: 44.8–47.5) had evidence of a used latrine. Nine districts had a prevalence of TF below the elimination threshold of 5%. In hyperendemic areas, 3–5 years of implementation of SAFE is insufficient to achieve trachoma elimination as a public health problem; additional years of SAFE and several rounds of TIS will be required before trachoma is eliminated.

Association of community sanitation usage with soil-transmitted helminth infections among school-aged children in Amhara Region, Ethiopia

BACKGROUND

Globally, in 2010, approximately 1.5 billion people were infected with at least one species of soil-transmitted helminth (STH), Ascaris lumbricoides, Trichuris trichiura, hookworm (Ancylostoma duodenale and Necator americanus). Infection occurs through ingestion or contact (hookworm) with eggs or larvae in the environment from fecal contamination. To control these infections, the World Health Organization recommends periodic mass treatment of at-risk populations with deworming drugs. Prevention of these infections typically relies on improved excreta containment and disposal. Most evidence of the relationship between sanitation and STH has focused on household-level access or usage, rather than community-level sanitation usage. We examined the association between the proportion of households in a community with latrines in use and prevalence of STH infections among school-aged children.

METHODS

Data on STH prevalence and household latrine usage were obtained during four population-based, cross-sectional surveys conducted between 2011 and 2014 in Amhara, Ethiopia. Multilevel regression was used to estimate the association between the proportion of households in the community with latrines in use and presence of STH infection, indicated by > 0 eggs in stool samples from children 6-15 years old.

RESULTS

Prevalence of STH infection was estimated as 22% (95% CI: 20-24%), 14% (95% CI: 13-16%), and 4% (95% CI: 4-5%) for hookworm, A. lumbricoides, and T. trichiura, respectively. Adjusting for individual, household, and community characteristics, hookworm prevalence was not associated with community sanitation usage. Trichuris trichuria prevalence was higher in communities with sanitation usage ≥ 60% versus sanitation usage < 20%. Association of community sanitation usage with A. lumbricoides prevalence depended on household sanitation. Community sanitation usage was not associated with A. lumbricoides prevalence among households with latrines in use. Among households without latrines in use, A. lumbricoides prevalence was higher comparing communities with sanitation usage ≥ 60% versus < 20%. Households with a latrine in use had lower prevalence of A. lumbricoides compared to households without latrines in use only in communities where sanitation usage was ≥ 80%.

CONCLUSIONS

We found no evidence of a protective association between community sanitation usage and STH infection. The relationship between STH infection and community sanitation usage may be complex and requires further study.

Active trachoma and community use of sanitation, Ethiopia

Objective

To investigate, in Amhara, Ethiopia, the association between prevalence of active trachoma among children aged 1–9 years and community sanitation usage.

Methods

Between 2011 and 2014, prevalence of trachoma and household pit latrine usage were measured in five population-based cross-sectional surveys. Data on observed indicators of latrine use were aggregated into a measure of community sanitation usage calculated as the proportion of households with a latrine in use. All household members were examined for clinical signs, i.e. trachomatous inflammation, follicular and/or intense, indicative of active trachoma. Multilevel logistic regression was used to estimate prevalence odds ratios (OR) and 95% confidence intervals (CI), adjusting for community, household and individual factors, and to evaluate modification by household latrine use and water access.

Findings

In surveyed areas, prevalence of active trachoma among children was estimated to be 29% (95% CI: 28–30) and mean community sanitation usage was 47% (95% CI: 45–48). Despite significant modification (p < 0.0001), no pattern in stratified ORs was detected. Summarizing across strata, community sanitation usage values of 60 to < 80% and ≥ 80% were associated with lower prevalence odds of active trachoma, compared with community sanitation usage of < 20% (OR: 0.76; 95% CI: 0.57–1.03 and OR: 0.67; 95% CI: 0.48–0.95, respectively).

Conclusion

In Amhara, Ethiopia, a negative correlation was observed between community sanitation usage and prevalence of active trachoma among children, highlighting the need for continued efforts to encourage higher levels of sanitation usage and to support sustained use throughout the community, not simply at the household level.

Prediction of Low Community Sanitation Coverage Using Environmental and Sociodemographic Factors in Amhara Region, Ethiopia

This study developed and validated a model for predicting the probability that communities in Amhara Region, Ethiopia, have low sanitation coverage, based on environmental and sociodemographic conditions. Community sanitation coverage was measured between 2011 and 2014 through trachoma control program evaluation surveys. Information on environmental and sociodemographic conditions was obtained from available data sources and linked with community data using a geographic information system. Logistic regression was used to identify predictors of low community sanitation coverage (< 20% versus ≥ 20%). The selected model was geographically and temporally validated. Model-predicted probabilities of low community sanitation coverage were mapped. Among 1,502 communities, 344 (22.90%) had coverage below 20%. The selected model included measures for high topsoil gravel content, an indicator for low-lying land, population density, altitude, and rainfall and had reasonable predictive discrimination (area under the curve = 0.75, 95% confidence interval = 0.72, 0.78). Measures of soil stability were strongly associated with low community sanitation coverage, controlling for community wealth, and other factors. A model using available environmental and sociodemographic data predicted low community sanitation coverage for areas across Amhara Region with fair discrimination. This approach could assist sanitation programs and trachoma control programs, scaling up or in hyperendemic areas, to target vulnerable areas with additional activities or alternate technologies.

Prevalence of trachoma at sub-district level in ethiopia: determining when to stop mass azithromycin distribution

Background

To eliminate blinding trachoma, the World Health Organization emphasizes implementing the SAFE strategy, which includes annual mass drug administration (MDA) with azithromycin to the whole population of endemic districts. Prevalence surveys to assess impact at the district level are recommended after at least 3 years of intervention. The decision to stop MDA is based on a prevalence of trachomatous inflammation follicular (TF) among children aged 1–9 years below 5% at the sub-district level, as determined by an additional round of surveys limited within districts where TF prevalence is below 10%. We conducted impact surveys powered to estimate prevalence simultaneously at the sub-district and district in two zones of Amhara, Ethiopia to determine whether MDA could be stopped.

Methodology

Seventy-two separate population-based, sub-district surveys were conducted in 25 districts. In each survey all residents from 10 randomly selected clusters were screened for clinical signs of trachoma. Data were weighted according to selection probabilities and adjusted for correlation due to clustering.

Principal Findings

Overall, 89,735 residents were registered from 21,327 households of whom 72,452 people (80.7%) were examined. The prevalence of TF in children aged 1–9 years was below 5% in six sub-districts and two districts. Sub-district level prevalence of TF in children aged 1–9 years ranged from 0.9–76.9% and district-level from 0.9–67.0%. In only one district was the prevalence of trichiasis below 0.1%.

Conclusions/Significance

The experience from these zones in Ethiopia demonstrates that impact assessments designed to give a prevalence estimate of TF at sub-district level are possible, although the scale of the work was challenging. Given the assessed district-level prevalence of TF, sub-district-level surveys would have been warranted in only five districts. Interpretation was not as simple as stopping MDA in sub-districts below 5% given programmatic challenges of exempting sub-districts from a highly regarded program and the proximity of hyper-endemic sub-districts.

Trachoma, the leading cause of preventable blindness, is targeted for “elimination as a public health problem” by the year 2020. National programs are implementing the recommended strategy of surgery, antibiotics, facial cleanliness, and environmental improvements (SAFE) to meet this target. Many programs are currently facing the decision of when to scale down interventions, particularly mass drug administration (MDA) of azithromycin. We implemented large population-based surveys in two different zones of the Amhara National Regional State of Ethiopia. Rather than conducting an impact assessment first at the district level, followed by additional sub-district-level surveys, we took a novel approach to measure the prevalence of trachoma at sub-district level to be able to make an immediate decision of whether to stop MDA. Over 72,000 people in 714 communities in 72 sub-districts were examined for clinical signs of trachoma. We identified only six sub-districts that met criteria for being able to stop MDA. Our work demonstrates that determining the prevalence of trachoma at sub-district level is feasible but requires significant resources. In this hyper-endemic setting, sub-district-level surveys were not needed in the majority of districts. Overall, the clinical data suggest some decline in trachoma within these areas since the SAFE strategy was implemented.

Trachoma among children in community surveys from four African countries and implications of using school surveys for evaluating prevalence

BACKGROUND

School surveys provide a convenient platform to obtain large child cohorts from multiple communities and are widely used as a proxy to determine community prevalence of neglected tropical diseases. The purpose of this study was to compare trachoma prevalence between preschool- and school-aged children and children who attend and do not attend school.

METHODS

We analysed data from community-based trachoma surveys conducted from 2008-2011 in Ethiopia, Mali, Niger and Nigeria. The surveys utilised a cross-sectional, randomised cluster design. Individual-level data on school attendance was collected.

RESULTS

Overall, 75 864 children aged 1-15 years from 2100 communities were included in the analysis. The prevalence of trachomatous inflammation follicular (TF) among these children in surveyed districts was 19.1% (95% CI 17.9-20.2%) in Ethiopia, 6.2% (95% CI 5.4-6.9%) in Niger, 4.6% (95% CI 4.2-4.9%) in Mali and 4.2% (95% CI 3.5-4.9%) in Nigeria. Controlling for age, sex and clustering, the OR of TF for school-attendees compared to non-attendees was 0.64 (95% CI 0.56-0.73) in Ethiopia, 0.67 (95% CI 0.56-0.80) in Mali, 1.03 (95% CI 0.81-1.16) in Niger and 1.06, (95% CI 0.65-1.73) in Nigeria.

CONCLUSION

Estimating the prevalence of trachoma through examination of only school-going children risks underestimating the true prevalence.

Evaluation of household latrine coverage in Kewot woreda, Ethiopia, 3 years after implementing interventions to control blinding trachoma

The SAFE strategy for trachoma control includes Surgery, Antibiotic distribution, Facial cleanliness and Environmental improvements, including promotion of latrine construction. In this study, household latrine coverage was estimated in order to evaluate SAFE implementation in a district of Ethiopia where reported coverage in rural areas was 97%. Characteristics of latrine adopters and non-adopters were explored. Interviews were conducted in 442 households selected at random in a multistage cluster sample. Overall, estimated household latrine coverage was 56.2% (95% CI 37.5-74.8%) and in rural areas coverage was 67.7% (95% CI 59.6-75.7%). Previously owning a latrine was reported by 12.7% (95% CI 8.9-16.5%) of respondents, of which 32.0% (95% CI 15.9-48.2%) had built a replacement. Latrine adopters were more likely to be male (P < 0.0001), to report their primary occupation as agriculture (P < 0.0001), have more than five residents in their household (P = 0.004) and live in a rural area (P < 0.0001). Respondents who were advised by a health extension worker (P < 0.0001) or development agent (P < 0.0001) were more likely to have built a latrine. Household latrine coverage has increased from the 2007 zonal estimate (8.9%), but was lower than that reported. Latrine promotion should include emphasis on rebuilding latrines. More support may be needed by small households as well as those with a female head if universal latrine access is to be achieved in Kewot.

A novel electronic data collection system for large-scale surveys of neglected tropical diseases

BACKGROUND

Large cross-sectional household surveys are common for measuring indicators of neglected tropical disease control programs. As an alternative to standard paper-based data collection, we utilized novel paperless technology to collect data electronically from over 12,000 households in Ethiopia.

METHODOLOGY

We conducted a needs assessment to design an Android-based electronic data collection and management system. We then evaluated the system by reporting results of a pilot trial and from comparisons of two, large-scale surveys; one with traditional paper questionnaires and the other with tablet computers, including accuracy, person-time days, and costs incurred.

PRINCIPLE FINDINGS

The electronic data collection system met core functions in household surveys and overcame constraints identified in the needs assessment. Pilot data recorders took 264 (standard deviation (SD) 152 sec) and 260 sec (SD 122 sec) per person registered to complete household surveys using paper and tablets, respectively (P = 0.77). Data recorders felt a lack of connection with the interviewee during the first days using electronic devices, but preferred to collect data electronically in future surveys. Electronic data collection saved time by giving results immediately, obviating the need for double data entry and cross-correcting. The proportion of identified data entry errors in disease classification did not differ between the two data collection methods. Geographic coordinates collected using the tablets were more accurate than coordinates transcribed on a paper form. Costs of the equipment required for electronic data collection was approximately the same cost incurred for data entry of questionnaires, whereas repeated use of the electronic equipment may increase cost savings.

CONCLUSIONS/SIGNIFICANCE

Conducting a needs assessment and pilot testing allowed the design to specifically match the functionality required for surveys. Electronic data collection using an Android-based technology was suitable for a large-scale health survey, saved time, provided more accurate geo-coordinates, and was preferred by recorders over standard paper-based questionnaires.

Performance of local light microscopy and the ParaScreen Pan/Pf rapid diagnostic test to detect malaria in health centers in Northwest Ethiopia

Background

Diagnostic tests are recommended for suspected malaria cases before treatment, but comparative performance of microscopy and rapid diagnostic tests (RDTs) at rural health centers has rarely been studied compared to independent expert microscopy.

Methods

Participants (N = 1997) with presumptive malaria were recruited from ten health centers with a range of transmission intensities in Amhara Regional State, Northwest Ethiopia during October to December 2007. Microscopy and ParaScreen Pan/Pf® RDT were done immediately by health center technicians. Blood slides were re-examined later at a central laboratory by independent expert microscopists.

Results

Of 1,997 febrile patients, 475 (23.8%) were positive by expert microscopists, with 57.7% P.falciparum, 24.6% P.vivax and 17.7% mixed infections. Sensitivity of health center microscopists for any malaria species was >90% in five health centers (four of which had the highest prevalence), >70% in nine centers and 44% in one site with lowest prevalence. Specificity for health center microscopy was very good (>95%) in all centers. For ParaScreen RDT, sensitivity was ≥90% in three centers, ≥70% in six and <60% in four centers. Specificity was ≥90% in all centers except one where it was 85%.

Conclusions

Health center microscopists performed well in nine of the ten health centers; while for ParaScreen RDT they performed well in only six centers. Overall the accuracy of local microscopy exceeded that of RDT for all outcomes. This study supports the introduction of RDTs only if accompanied by appropriate training, frequent supervision and quality control at all levels. Deficiencies in RDT use at some health centers must be rectified before universal replacement of good routine microscopy with RDTs. Maintenance and strengthening of good quality microscopy remains a priority at health center level.

Effect of a community intervention with pit latrines in five districts of Amhara, Ethiopia

OBJECTIVE

To evaluate the change in household latrine coverage and investigated predictors of latrine uptake after 3 years of implementation of trachoma control interventions in Dera, Ebinat, Estie, Enebsie Sarmedir and Huleteju Enese districts of Amhara, Ethiopia.

METHODS

Before and after study, baseline surveys were conducted prior to programme implementation and an evaluation after 3 years of interventions. Multi-stage cluster random sampling was used in both surveys.

RESULTS

A total of 1096 and 1117 households were sampled and assessed for the presence of household latrines at baseline and evaluation, respectively. The proportion of households with a pit latrine increased by 32.3% overall (95% confidence interval [CI]: 27.9-38.0), ranging from 8.0% (95% CI: 5.1-10.8) in Ebinat to 58.9% (95% CI: 51.9-66.8) in Enebsie Sarmedir. Logistic regression analysis of associations between household latrine ownership and potential factors showed that increasing household size (OR(per additional person) = 1.2[95% CI: 1.1-1.3]), higher socio-economic status (tin roof) (OR = 1.8[95% CI: 1.2-2.9]) and participation in health education (OR = 1.6[95% CI: 1.1-2.5]) were independent predictors of latrine ownership.

CONCLUSION

Our study documented heterogeneous increase in household latrine coverage after 3 years of latrine promotion; two of five districts had achieved Millennium Development Goal 7.9 and halved the proportion of households without latrine access. We attribute the striking increase in household latrines to increased political commitment of the local government and intensive community mobilisation under the trachoma control programme in Amhara region.

Estimation of effects of community intervention with antibiotics, facial cleanliness, and environmental improvement (A,F,E) in five districts of Ethiopia hyperendemic for trachoma

AIMS

The WHO recommends the SAFE (surgery, antibiotics, facial cleanliness and environmental improvement) strategy for trachoma control. We aimed to investigate the association between active trachoma and community intervention with antibiotics, facial cleanliness, environmental improvement (A,F,E) components of SAFE in five trachoma hyperendemic districts of Amhara region, Ethiopia.

METHODS

Cluster random surveys were undertaken to evaluate SAFE following 3 years of interventions. Children aged 1-9 years were examined for trachoma signs using the WHO simplified grading system and structured questionnaires used to assess uptake of A, F and E. Active trachoma signs (trachomatous inflammation-follicular (TF) and trachomatous inflammation-intense (TI)) were used to derive an ordinal severity score where TI was considered more severe than TF. Associations between active trachoma and potential factors were investigated using ordinal logistic multilevel regression models.

RESULTS

A total of 1813 children aged 1-9 years were included in the analysis. Factors independently associated with reduced odds of active trachoma signs were: number of times treated with azithromycin (p-trend=0.026); months since last mass azithromycin distribution (p-trend<0.001); clean face (OR=0.6; 95% CI 0.5 to 0.8); and household pit latrine (OR=0.8; 95% CI 0.7 to 0.9).

CONCLUSION

These findings are important, since they make the case for continued implementing the A,F,E interventions simultaneously, and suggest appropriate timing of SAFE evaluations within 6-12 months after the last mass azithromycin distribution.

Evaluation of three years of the SAFE strategy (Surgery, Antibiotics, Facial cleanliness and Environmental improvement) for trachoma control in five districts of Ethiopia hyperendemic for trachoma

Trachoma surveys were conducted at baseline in five districts of Amhara National Regional State, Ethiopia (7478 participants in 1096 households) and at 3-year evaluation (5762 participants in 1117 households). Uptake of SAFE was assessed with programme monitoring data and interviews, and children (1-6 years) were swabbed for detection of ocular Chlamydia. At evaluation, 23,933 people had received trichiasis surgery; 93% of participants reported taking azithromycin at least once; 67% of household respondents (range 46-93) reported participation in trachoma health education; and household latrine coverage increased from 2% to 34%. In children aged 1-9 years percentage decline, by district, for outcomes was: 32% (95% CI 19-48) to 88% (95% CI 83-91) for trachomatous inflammation-follicular (TF); 87% (95% CI 83-91) to 99% (95% CI 97-100) for trachomatous inflammation-intense (TI); and 31% increase (95% CI -42 to -19) to 89% decrease (95% CI 85-93) for unclean face; and in adults percentage decline in trichiasis was 45% (95% CI -13 to 78) to 92% (95% CI 78-96). Overall prevalence of swabs positive for ocular Chlamydia was 3.1%. Although there were substantial reductions in outcomes in children and adults, the presence of ocular Chlamydia and TF in children suggests ongoing transmission. Continued implementation of SAFE is warranted.

Individual, household and environmental risk factors for malaria infection in Amhara, Oromia and SNNP regions of Ethiopia

We assessed malaria infection in relation to age, altitude, rainfall, socio-economic factors and coverage of control measures in a representative sample of 11437 people in Amhara, Oromia and SNNP regions of Ethiopia in December 2006-January 2007. Surveys were conducted in 224 randomly selected clusters of 25 households (overall sample of 27884 people in 5708 households). In 11538 blood slides examined from alternate households (83% of those eligible), malaria prevalence in people of all ages was 4.1% (95% CI 3.4-4.9), with 56.5% of infections being Plasmodium falciparum. At least one mosquito net or one long-lasting insecticidal net (LLIN) was present in 37.0% (95% CI 31.1-43.3) and 19.6% (95% CI 15.5-24.5) of households, respectively. In multivariate analysis (n=11437; 82% of those eligible), significant protective factors were: number of LLINs per household (odds ratio [OR] (per additional net)=0.60; 95% CI 0.40-0.89), living at higher altitude (OR (per 100 m)=0.95; 95% CI 0.90-1.00) and household wealth (OR (per unit increase in asset index)=0.79; 95% CI 0.66-0.94). Malaria prevalence was positively associated with peak monthly rainfall in the year before the survey (OR (per additional 10 mm rain)=1.10; 95% CI 1.03-1.18). People living above 2000 m and people of all ages are still at significant risk of malaria infection.

Evaluation of light microscopy and rapid diagnostic test for the detection of malaria under operational field conditions: a household survey in Ethiopia

BACKGROUND

In most resource-poor settings, malaria is usually diagnosed based on clinical signs and symptoms and not by detection of parasites in the blood using microscopy or rapid diagnostic tests (RDT). In population-based malaria surveys, accurate diagnosis is important: microscopy provides the gold standard, whilst RDTs allow immediate findings and treatment. The concordance between RDTs and microscopy in low or unstable transmission areas has not been evaluated.

OBJECTIVES

This study aimed to estimate the prevalence of malaria parasites in randomly selected malarious areas of Amhara, Oromia, and Southern Nations, Nationalities and Peoples' (SNNP) regions of Ethiopia, using microscopy and RDT, and to investigate the agreement between microscopy and RDT under field conditions.

METHODS

A population-based survey was conducted in 224 randomly selected clusters of 25 households each in Amhara, Oromia and SNNP regions, between December 2006 and February 2007. Fingerpick blood samples from all persons living in even-numbered households were tested using two methods: light microscopy of Giemsa-stained blood slides; and RDT (ParaScreen device for Pan/Pf).

RESULTS

A total of 13,960 people were eligible for malaria parasite testing of whom 11,504 (82%) were included in the analysis. Overall slide positivity rate was 4.1% (95% confidence interval [CI] 3.4-5.0%) while ParaScreen RDT was positive in 3.3% (95% CI 2.6-4.1%) of those tested. Considering microscopy as the gold standard, ParaScreen RDT exhibited high specificity (98.5%; 95% CI 98.3-98.7) and moderate sensitivity (47.5%; 95% CI 42.8-52.2) with a positive predictive value of 56.8% (95% CI 51.7-61.9) and negative predictive value of 97.6% (95% CI 97.6-98.1%) under field conditions.

CONCLUSION

Blood slide microscopy remains the preferred option for population-based prevalence surveys of malaria parasitaemia. The level of agreement between microscopy and RDT warrants further investigation in different transmission settings and in the clinical situation.

Risk factors for active trachoma in children and trichiasis in adults: a household survey in Amhara Regional State, Ethiopia

Identification of risk factors is essential for planning and implementing effective trachoma control programmes. We aimed to investigate risk factors for active trachoma and trichiasis in Amhara Regional State, Ethiopia. A survey was undertaken and eligible participants (children aged 1-9 years and adults aged 15 years and above) examined for trachoma. Risk factors were assessed through interviews and observations. Using ordinal logistic regression, associations between signs of active trachoma in children and potential risk factors were explored. Associations between trichiasis in adults and potential risk factors were investigated using conventional logistic regression. A total of 5427 children from 2845 households and 9098 adults from 4039 households were included in the analysis. Ocular discharge [odds ratio (OR)=5.9; 95% CI 4.8-7.2], nasal discharge (OR=1.6; 95% CI 1.3-1.9), thatch roof in household (OR=1.3; 95% CI 1.0-1.5), no electricity in household (OR=2.4; 95% CI 1.3-4.3) and increasing altitude (Ptrend<0.001) were independently associated with severity of active trachoma. Trichiasis was associated with increasing age (ORper 5 year increase=1.5; 95% CI 1.4-1.7), female gender (OR=4.5; 95% CI 3.5-5.8), increasing prevalence of active trachoma in children (Ptrend=0.003) and increasing altitude (Ptrend=0.015).

Adaptive significance of male parental care in a monogamous mammal

Paternal behaviour presumably evolved because male care of young was critical for offspring survival. We report field evidence indicating that paternal behaviour enhances offspring survival in a monogamous mammal, the biparental California mouse, Peromyscus californicus. Male removal resulted in lower offspring survival in father-absent than in father-present families. New males took up residence with widowed females, but usually after females had stopped lactating, suggesting that the importance of the father is not primarily protection against infanticidal intruders but rather direct care of young.

Sex-biased mortality in woodrats occurs in the absence of parental intervention

Male-biased mortality in young animals is often viewed as adaptive discrimination against male offspring by parents unable to raise reproductively competitive sons. Unequivocal evidence of the presence or absence of parental discrimination against males is lacking, however, and the adaptive interpretation of male-biased mortality is confounded by an alternative explanation that it reflects differential energetic requirements between the sexes (due to sexual selection for large size in mature males) independent of parental manipulation. To determine whether maternal discrimination against offspring explains postnatal mortality in a sexually dimorphic rodent, we examined patterns of growth and mortality in offspring of food-restricted and food-enriched lactating bushy-tailed woodrats, Neotoma cinerea. We also monitored mothers and their litters daily throughout lactation for evidence of maternal discrimination against offspring. Offspring of food-restricted mothers showed depressed growth, and mortality of offspring born to both food-restricted and food-enriched mothers was male-biased, but in the absence of maternal discrimination. Offspring that died were no less likely to be attached to their mother's teats in the 10 days prior to death than were offspring that successfully weaned. Similarly, offspring of food-restricted mothers were attached as often as were offspring of food-enriched mothers. In a series of behavioural arena trials in the first 10 days after birth, restricted mothers were no less attentive toward their sons than they were to their daughters, nor did mothers treat their offspring that did not survive to weaning differently from those that survived. Our findings provide empirical evidence that postnatal, sex-biased mortality in offspring is not necessarily due to parental intervention, and they call into question the adaptive interpretations of previous examples of sex-biased offspring mortality. Copyright 1998 The Association for the Study of Animal Behaviour Copyright 1998 The Association for the Study of Animal Behaviour.

Littoral feeding in a high-density insular population of Sorex cinereus

In a high-density insular population of masked shrews (Sorex cinereus), Diptera, amphipods, Araneae, and Coleoptera dominated the diet. The prominence of littoral amphipods and kelp flies in the diet indicates a pattern of beach foraging not previously described for this shrew. Remains of these prey were found in shrews captured as far as 60 m inland. We speculate that abundant littoral invertebrate prey, present throughout much of the year, partly sustain the high number and extended breeding season of shrews on this island.