Molecular Confirmation of Anopheles stephensi Mosquitoes in the Al Hudaydah Governorate, Yemen, 2021 and 2022.

We detected malaria vector Anopheles stephensi mosquitoes in the Al Hudaydah governorate in Yemen by using DNA sequencing. We report 2 cytochrome c oxidase subunit I haplotypes, 1 previously found in Ethiopia, Somalia, Djibouti, and Yemen. These findings provide insight into invasive An. stephensi mosquitoes in Yemen and their connection to East Africa.

Public health impact of the spread of Anopheles stephensi in the WHO Eastern Mediterranean Region countries in Horn of Africa and Yemen: need for integrated vector surveillance and control.

BACKGROUND: Anopheles stephensi is an efficient vector of both Plasmodium falciparum and Plasmodium vivax in South Asia and the Middle East. The spread of An. stephensi to countries within the Horn of Africa threatens progress in malaria control in this region as well as the rest of sub-Saharan Africa. METHODS: The available malaria data and the timeline for the detection of An. stephensi was reviewed to analyse the role of An. stephensi in malaria transmission in Horn of Africa of the Eastern Mediterranean Region (EMR) in Djibouti, Somalia, Sudan and Yemen. RESULTS: Malaria incidence in Horn of Africa of EMR and Yemen, increased from 41.6 in 2015 to 61.5 cases per 1000 in 2020. The four countries from this region, Djibouti, Somalia, Sudan and Yemen had reported the detection of An. stephensi as of 2021. In Djibouti City, following its detection in 2012, the estimated incidence increased from 2.5 cases per 1000 in 2013 to 97.6 cases per 1000 in 2020. However, its contribution to malaria transmission in other major cities and in other countries, is unclear because of other factors, quality of the urban malaria data, human mobility, uncertainty about the actual arrival time of An. stephensi and poor entomological surveillance. CONCLUSIONS: While An. stephensi may explain a resurgence of malaria in Djibouti, further investigations are needed to understand its interpretation trends in urban malaria across the greater region. More investment for multisectoral approach and integrated surveillance and control should target all vectors particularly malaria and dengue vectors to guide interventions in urban areas.

Management of insecticides for use in disease vector control: a global survey.

BACKGROUND: Vector control plays a critical role in the prevention, control and elimination of vector-borne diseases, and interventions of vector control continue to depend largely on the action of chemical insecticides. A global survey was conducted on the management practices of vector control insecticides at country level to identify gaps to inform future strategies on pesticide management, seeking to improve efficacy of interventions and reduce the side-effects of chemicals used on health and the environment. METHODS: A survey by questionnaire on the management practices of vector control insecticides was disseminated among all WHO Member States. Data were analysed using descriptive statistics in MS Excel. RESULTS: Responses were received from 94 countries, or a 48% response rate. Capacity for insecticide resistance monitoring was established in 68-80% of the countries in most regions, often with external support; however, this capacity was largely lacking from the European & Others Region (i.e. Western & Eastern Europe, North America, Australia and New Zealand). Procurement of vector control insecticides was in 50-75% of countries taking place by agencies other than the central-level procuring agency, over which the central authorities lacked control, for example, to select the product or assure its quality, highlighting the importance of post-market monitoring. Moreover, some countries experienced problems with estimating the correct amounts for procurement, especially for emergency purposes. Large fractions (29-78%) of countries across regions showed shortcomings in worker safety, pesticide storage practices and pesticide waste disposal. Shortcomings were most pronounced in countries of the European & Others Region, which has long been relatively free from mosquito-borne diseases but has recently faced challenges of re-emerging vector-borne diseases. CONCLUSIONS: Critical shortcomings in the management of vector control insecticides are common in countries across regions, with risks of adverse pesticide effects on health and the environment. Advocacy and resource mobilization are needed at regional and country levels to address these challenges.

Multisectoral Approach to Address Chikungunya Outbreaks Driven by Human Mobility: A Systematic Review and Meta-Analysis.

BACKGROUND: The role of human mobility in the epidemiology of emerging Aedes-transmitted viral diseases is recognized but not fully understood. The objective of this systematic review and meta-analysis was to examine how human mobility patterns are driving chikungunya outbreaks. METHODS: Literature was systematically reviewed for studies on chikungunya prevalence in countries/territories with high-level evidence of human mobility-driven outbreaks, based on: (1) emergence of chikungunya outbreaks with epidemic chikungunya virus genotypes among displaced/migrant populations and their hosting communities; and (2) identification of imported index case(s) with epidemic genotypes phylogenetically related to the genotypes circulating during emerging or subsequent outbreaks. RESULTS: The meta-analysis of extracted prevalence data revealed that a large proportion of the population in countries/territories afflicted by outbreaks is still at risk of infection during future outbreaks. On the other hand, approximately one-half of suspected chikungunya cases could be infected with other co-circulating acute febrile illnesses. CONCLUSIONS: We discussed in this paper how human mobility-driven chikungunya outbreaks can be addressed, and how the involvement of several sectors in addition to the health sector in multisectoral approaches (MSAs) is important for prevention and control of chikungunya and other Aedes-transmitted arboviral outbreaks.

Access to and use of long-lasting insecticidal nets and factors associated with non-use among communities in malaria-endemic areas of Al Hudaydah governorate in the Tihama region, west of Yemen.

BACKGROUND: Universal coverage of the targeted malaria-endemic areas with long-lasting insecticidal nets (LLINs) is implemented as one of the key interventions for malaria control and elimination in Yemen. In 2013, through a mass campaign, LLINs were distributed to the targeted communities in Al Hudaydah governorate. This study aimed to assess the ownership of, access to, and use of LLINs. It also aimed to identify factors associated with not using LLINs in malaria-endemic areas of Al Hudaydah in the Tihama region, west of Yemen. METHODS: A cross-sectional survey was conducted in four districts (Ad Durayhimi, Al Marawi'ah, Al Mansuriyah and Bayt Al Faqiah) in Al Hudaydah during February 2016. A total of 701 households were included in this study. Data on socio-demographic characteristics and availability of LLINs were collected by interview and observation. Four indicators for malaria prevention using LLINs; proportion of households with at least one LLIN, proportion of households with at least one LLIN for every two people, proportion of population with access to LLINs in the surveyed households and proportion of population who slept under LLINs the previous night of the survey were calculated as indicated by Roll Back Malaria Monitoring and Evaluation Reference Group. Use to access ratio was assessed. Factors associated with not using LLINs among people with access were also investigated. RESULTS: Of 701 households with 4900 de facto population, ownership of at least one LLIN was 90.6%, while 24.1% owned at least one for every two people during the survey in 2016. The overall proportion of people with access to LLINs was 51.5% (95% CI 50.1-52.9). Only 19.0% (95% CI 17.9-20.1) slept under LLINs the night before the survey and the overall use to access ratio was 0.37. The proportions of children under 5 years of age with access to and use of LLINs were 13.7 and 42.5%, respectively. On the other hand, the proportions of pregnant women with access to and use of LLINs were 16.4 and 20.0%, respectively. Multivariable analysis identified that people living in Al Mansuriyah district [adjusted odds ratio (AOR) = 3.29, 95% confidence interval (CI)  1.35-8.01; P = 0.009)], having three or more damaged LLINs in the house (AOR = 2.76, 95% CI 1.79-4.25; P < 0.001), aged between 16 and 45 years old (AOR = 2.17, 95% CI 1.26-3.75; P = 0.005) or older (AOR = 2.17, 95% CI 1.09-4.29; P = 0.026) and living in huts (AOR = 1.59, 95% CI 1.09-2.32; P = 0.015) were significantly less likely to use LLINs. CONCLUSIONS: This study shows a low LLIN access rate among local communities targeted for universal LLIN coverage in Al Hudaydah, a malaria-endemic area of high transmission. This finding necessitates additional distribution channels following mass campaigns to maintain the universal coverage. Reduced use of LLINs among people with access in these communities together with the identified risks of non-use highlight the importance of conducting behaviour change communication campaigns to enhance using LLINs in areas with universal coverage.

High heterogeneity of malaria transmission and a large sub-patent and diverse reservoir of infection in Wusab As Safil district, Republic of Yemen.

BACKGROUND: Yemen remains the country with the highest malaria transmission within the Arabian Peninsula and a source of imported cases to neighbouring countries. METHODS: This study collected samples from individuals resident in a valley in Western Yemen as a baseline to examine infection prevalence for a future trial. As well as rapid diagnostic test (RDT) and microscopy, a filter paper blood spot was collected for molecular and serological analyses. RESULTS: Samples were collected from 2261 individuals from 12 clusters across a study area of approximately 100 km(2). Plasmodium falciparum infection prevalence was 12.4, 11.1 and 19.6% by RDT, microscopy and polymerase chain reaction (PCR), respectively. RDT and microscopy did not detect 45% of infections present, suggesting many infections were low-density. Infection prevalence and seroprevalence were highly heterogeneous between clusters, with evidence of higher exposure in clusters close to the wadi. The mean multiplicity of infection (MOI) was 2.3 and high heterozygosity and allelic richness were detected. CONCLUSIONS: This highly diverse parasite population suggests a high degree of transmissibility and coupled with the substantial proportion of low-density infections, may pose challenges for malaria control and elimination efforts.

Entomological aspects and the role of human behaviour in malaria transmission in a highland region of the Republic of Yemen.

BACKGROUND: The Republic of Yemen has the highest incidence of malaria in the Arabian Peninsula, yet little is known of its vectors or transmission dynamics. METHODS: A 24-month study of the vectors and related epidemiological aspects of malaria transmission was conducted in two villages in the Taiz region in 2004-2005. RESULTS: Cross-sectional blood film surveys recorded an overall malaria infection rate of 15.3 % (250/1638), with highest rates exceeding 30 % in one village in May and December 2005. With one exception, Plasmodium malariae, all infections were P. falciparum. Seven Anopheles species were identified among 3407 anophelines collected indoors using light traps (LT) and pyrethrum knockdown catches (PKD): Anopheles arabiensis (86.9 %), An. sergentii (9 %), An. azaniae, An. dthali, An. pretoriensis, An. coustani and An. algeriensis. Sequences for the standard barcode region of the mitochondrial COI gene confirmed the presence of two morphological forms of An. azaniae, the typical form and a previously unrecognized form not immediately identifiable as An. azaniae. ELISA detected Plasmodium sporozoites in 0.9 % of 2921 An. arabiensis (23 P. falciparum, two P. vivax) confirming this species as the primary malaria vector in Yemen. Plasmodium falciparum sporozoites were detected in An. sergentii (2/295) and a single female of An. algeriensis, incriminating both species as malaria vectors for the first time in Yemen. A vector in both wet and dry seasons, An. arabiensis was predominantly anthropophilic (human blood index = 0.86) with an entomological inoculation rate of 1.58 infective bites/person/year. Anopheles sergentii fed on cattle (67.3 %) and humans (48.3; 20.7 % mixed both species), but only 14.7 % were found in PKDs, indicating predominantly exophilic behaviour. A GIS analysis of geographic and socio-economic parameters revealed that An. arabiensis were significantly higher (P < 0.001) in houses with televisions, most likely due to the popular evening habit of viewing television collectively in houses with open doors and windows. CONCLUSIONS: The predominantly indoor human biting vectors recorded in this study could be targeted effectively with LLINs, indoor residual spraying and/or insecticide-treated window/door curtains reinforced by education to instil a perception that effective and affordable malaria prevention is achievable.

Glucose-6-phosphate dehydrogenase deficiency among Yemeni children residing in malaria-endemic areas of Hodeidah governorate and evaluation of a rapid diagnostic test for its detection.

BACKGROUND: Glucose-6-phosphate dehydrogenase (G6PD) deficiency, the most common genetic enzymopathy worldwide, is associated with an acute haemolytic anaemia in individuals exposed to primaquine. The present study aimed to determine G6PD deficiency among Yemeni children in malaria-endemic areas as well as to assess the performance of the CareStart™ G6PD rapid diagnostic test (RDT) for its detection. METHODS: A cross-sectional study recruiting 400 children from two rural districts in Hodeidah governorate was conducted. Socio-demographic data and blood samples were collected and G6PD deficiency was qualitatively detected in fresh blood in the field using the CareStart™ G6PD RDT, while the enzymatic assay was used to quantitatively measure enzyme activity. Performance of the CareStart™ G6PD RDT was assessed by calculating its sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) against the reference enzymatic assay. RESULTS: The ranges of enzyme activity were 0.14-18.45 and 0.21-15.94 units/g haemoglobin (U/gHb) for males and females, respectively. However, adjusted male median G6PD activity was 5.0 U/gHb. Considering the adjusted male median as representing 100 % normal enzyme activity, the prevalence rates of G6PD deficiency were 12.0 and 2.3 % at the cut-off activities of ≤60 and ≤10 %, respectively. Multivariable analysis showed that gender, district of residence and consanguinity between parents were independent risk factors for G6PD deficiency at the cut-off activity of ≤30 % of normal. The CareStart™ G6PD RDT showed 100 % sensitivity and NPV for detecting G6PD deficiency at the cut-off activities of ≤10 and ≤20 % of normal activity compared to the reference enzymatic method. However, it showed specificity levels of 90.0 and 95.4 % as well as positive/deficient predictive values (PPVs) of 18.0 and 66.0 % at the cut-off activities of ≤10 and ≤20 %, respectively, compared to the reference method. CONCLUSIONS: G6PD deficiency with enzyme activity of ≤60 % of normal is prevalent among 12.0 % of children residing in malaria-endemic areas of Hodeidah governorate, with 2.3 % having severe G6PD deficiency. Gender, district of residence and consanguinity between parents are significant independent predictors of G6PD deficiency at the cut-off activity of ≤30 % of normal among children in malaria-endemic areas of Hodeidah. The CareStart™ G6PD RDT proved reliable as a point-of-care test to screen for severely G6PD-deficient patients, with 100 % sensitivity and NPV, and it can be used for making clinical decisions prior to the administration of primaquine in malaria elimination strategies.

A household-based survey of knowledge, attitudes and practices towards dengue fever among local urban communities in Taiz Governorate, Yemen.

BACKGROUND: Yemen has witnessed several dengue fever outbreaks coincident with the social unrest and war in the country. The aim of the present study was to describe the knowledge, attitudes and practices (KAPs) of at-risk urban populations residing in Taiz, southwest of Yemen. In addition, factors possibly associated with poor preventive practices were investigated. METHODS: A household-based, cross-sectional survey was conducted in three urban districts encompassing 383 households. Data on the socio-demographic characteristics and KAPs of the participating household heads were collected using a pre-designed, structured questionnaire. The association of socio-demographic characteristics, knowledge and attitudes of the population with poor preventive practices against dengue fever was then analyzed using logistic regression. RESULTS: More than 90.0 % of respondent household heads had correct knowledge about fever, headache and joint pain as common signs and symptoms of dengue fever. Moreover, muscular pain and bleeding were perceived by more than 80.0 % of the respondents as being associated with dengue fever; however, only 65.0 % of the respondents reported skin rash as a sign of dengue fever. More than 95.0 % of respondents agreed about the seriousness and possible transmission of dengue fever; however, negative attitudes regarding the facts of being at risk of the disease and that the infection is preventable were expressed by 15.0 % of respondents. Despite the good level of knowledge and attitudes of the respondent population, poor preventive practices were common. Bivariate analysis identified poor knowledge of dengue signs and symptoms (OR = 2.1, 95 % CI = 1.24-3.68; P = 0.005) and its vector (OR = 2.1, 95 % CI = 1.14-3.84; P = 0.016) as factors significantly associated with poor preventive practices. However, multivariable analysis showed that poor knowledge of the vector is an independent predictor of poor preventive practices of the population (adjusted OR = 2.1, 95 % CI = 1.14-3.84; P = 0.018). CONCLUSION: The majority of people in urban communities of Taiz have a clear understanding of most signs/symptoms of dengue fever as well as positive attitudes towards the seriousness and possible transmissibility of dengue fever. However, negative attitudes regarding their perception of the risk and possible prevention of the infection are prevailing among a small proportion of the population and need to be targeted by educational campaigns. It appears that the good level of the population knowledge of the signs/symptoms of dengue fever and the factors contributing to the spread and control of its vectors did not translate into good practices.

Perceived needs of disease vector control programs: A review and synthesis of (sub)national assessments from South Asia and the Middle East.

Systems for disease vector control should be effective, efficient, and flexible to be able to tackle contemporary challenges and threats in the control and elimination of vector-borne diseases. As a priority activity towards the strengthening of vector control systems, it has been advocated that countries conduct a vector-control needs assessment. A review was carried out of the perceived needs for disease vector control programs among eleven countries and subnational states in South Asia and the Middle East. In each country or state, independent teams conducted vector control needs assessment with engagement of stakeholders. Important weaknesses were described for malaria, dengue and leishmaniases regarding vector surveillance, insecticide susceptibility testing, monitoring and evaluation of operations, entomological capacity and laboratory infrastructure. In addition, community mobilization and intersectoral collaboration showed important gaps. Countries and states expressed concern about insecticide resistance that could reduce the continued effectiveness of interventions, which demands improved monitoring. Moreover, attainment of disease elimination necessitates enhanced vector surveillance. Vector control needs assessment provided a useful planning tool for systematic strengthening of vector control systems. A limitation in conducting the vector control needs assessment was that it is time- and resource-intensive. To increase the feasibility and utility of national assessments, an abridged version of the guidance should focus on operationally relevant topics of the assessment. Similar reviews are needed in other regions with different contextual conditions.

National mapping of schistosomiasis, soil-transmitted helminthiasis and anaemia in Yemen: Towards better national control and elimination.

BACKGROUND: Schistosomiasis (SCH) and soil-transmitted helminthiasis (STH) are known to be endemic in Yemen. However, the distribution of both diseases had not previously been assessed by a well-structured national mapping study covering all governorates. The main aim of this study was, therefore, to map the prevalence of SCH and STH in Yemen in order to better inform implementation of effective national control and elimination interventions. The assessment of the distribution of anaemia was also included as a well-known consequence of infection with both SCH and STH. Secondarily, the study aimed to provide a broad indication of the impact of large-scale treatment on the distribution of infection. METHODOLOGY AND PRINCIPAL FINDINGS: To achive these aims, 80,432 children (10-14 years old) from 2,664 schools in 332 of Yemen's 333 districts were included, in 2014, into this national cross-sectional survey. Countrywide, 63.3% (210/332) and 75.6% (251/332) of districts were found to be endemic for SCH and STH respectively. More districts were affected by intestinal than urogenital SCH (54.2% and 31.6% respectively). SCH infection was mostly mild and moderate, with no districts reporting high infection. One quarter (24.4%) of Yemeni districts had high or moderate levels of Ascaris lumbricoides infection. Infection with Trichuris trichiura was the second most common STH (44.9% of districts infected) after A. lumbricoides (68.1%). Hookworm was the least prevalent STH (9.0%). Anaemia was prevalent in 96.4% of districts; it represented a severe public health problem (prevalence ≥ 40%) in 26.5% of districts, and a mild to moderate problem in two thirds of the districts (33.7% and 36.1% respectively). CONCLUSION: This study provided the first comprehensive mapping of SCH, STH, and anaemia across the country. This formed the basis for evaluating and continuing the national control and elimination programme for these neglected tropical diseases in Yemen.

Comment on: Emergence of the invasive malaria vector Anopheles stephensi in Khartoum State, Central Sudan.

This letter comments on the article "Emergence of the invasive malaria vector Anopheles stephensi in Khartoum State, Central Sudan" published in Parasites and Vectors 2021, 14:511. Here we aim of provide a response to this paper in the broader context of the invasion and spread of An. stephensi in the Horn of Africa, and the required response to it. We agree with the authors that the arrival of this invasive vector in Khartoum State is of high public health concern. Equally concerning, however, we found that the detection of the vector by the authors in 2018 seemingly took 3 years to communicate to the Ministry of Health and World Health Organization (WHO), and was reliant on an academic journal. We consider that this short report sets a poor example of how public health threats should be reported. Suitable communication alternatives to alert public health authorities to such threats have been put in place by the WHO and its Member States, and are well known to at least some of the authors of the short report. We would like to encourage all readers not to follow the example of Ahmed et al. but instead act as responsible public health professionals by drawing on the established reporting mechanisms and escalate potential threats as soon as they are identified.

Recent trends in global insecticide use for disease vector control and potential implications for resistance management.

Insecticides have played a major role in the prevention, control, and elimination of vector-borne diseases, but insecticide resistance threatens the efficacy of available vector control tools. A global survey was conducted to investigate vector control insecticide use from 2010 to 2019. Out of 140 countries selected as sample for the study, 87 countries responded. Also, data on ex-factory deliveries of insecticide-treated nets (ITNs) were analyzed. Insecticide operational use was highest for control of malaria, followed by dengue, leishmaniasis and Chagas disease. Vector control relied on few insecticide classes with pyrethroids the most used overall. Results indicated that IRS programs have been slow to react to detection of pyrethroid resistance, while proactive resistance management using insecticides with unrelated modes of action was generally weak. The intensive use of recently introduced insecticide products raised concern about product stewardship regarding the preservation of insecticide susceptibility in vector populations. Resistance management was weakest for control of dengue, leishmaniasis or Chagas disease. Therefore, it will be vital that vector control programs coordinate on insecticide procurement, planning, implementation, resistance monitoring, and capacity building. Moreover, increased consideration should be given to alternative vector control tools that prevent the development of insecticide resistance.

Pesticide lifecycle management in agriculture and public health: Where are the gaps?

Pesticide lifecycle management encompasses a range of elements from legislation, regulation, manufacturing, application, risk reduction, monitoring, and enforcement to disposal of pesticide waste. A survey was conducted in 2017-2018 to describe the contemporary global status of pesticide lifecycle management, to identify where the gaps are found. A three-tiered questionnaire was distributed to government entities in 194 countries. The response rate was 29%, 27% and 48% to the first, second and third part of the questionnaire, respectively. The results showed gaps for most of the selected indicators of pesticide management, suggesting that pesticide efficacy and safety to human health and the environment are likely being compromised at various stages of the pesticide lifecycle, and at varying degrees across the globe. Low-income countries generally had the highest incidence of gaps. Particular shortcomings were deficiencies in pesticide legislation, inadequate capacity for pesticide registration, protection against occupational exposure to pesticides, consumer protection against residues in food, and environmental protection against pesticide contamination. Policy support for, and implementation of, pesticide use-reduction strategies such as integrated pest management and integrated vector management has been inadequate across regions. Priority actions for structural improvement in pesticide lifecycle management are proposed, including pesticide use-reduction strategies, targeted interventions, and resource mobilization.

Impact of population displacement and forced movements on the transmission and outbreaks of Aedes-borne viral diseases: Dengue as a model.

Population displacement and other forced movement patterns following natural disasters, armed conflicts or due to socioeconomic reasons contribute to the global emergence of Aedes-borne viral disease epidemics. In particular, dengue epidemiology is critically affected by situations of displacement and forced movement patterns, particularly within and across borders. In this respect, waves of human movements have been a major driver for the changing epidemiology and outbreaks of the disease on local, regional and global scales. Both emerging dengue autochthonous transmission and outbreaks in countries known to be non-endemic and co-circulation and hyperendemicity with multiple dengue virus serotypes have led to the emergence of severe disease forms such as dengue hemorrhagic fever and dengue shock syndrome. This paper reviews the emergence of dengue outbreaks driven by population displacement and forced movements following natural disasters and conflicts within the context of regional and sub-regional groupings.

Onchocerca volvulus infection in Tihama region - west of Yemen: Continuing transmission in ivermectin-targeted endemic foci and unveiled endemicity in districts with previously unknown status.

BACKGROUND: Onchocerciasis in Yemen is one of the most neglected diseases, where baseline estimates of onchocerciasis and monitoring of the impact of ivermectin regularly administered to the affected individuals on its transmission are lacking. Therefore, this study aimed to determine the anti-Ov16 IgG4 seroprevalence among local communities of Hodeidah and Al-Mahwit governorates of Tihama region. The factors possibly associated with previous exposure to infection were also studied. METHODOLOGY/PRINCIPAL FINDINGS: This cross-sectional study was conducted in two ivermectin-targeted districts endemic for onchocerciasis in Hodeidah and Al-Mahwit and two untargeted districts with unknown previous endemicity in Hodeidah between February and July 2017. For 508 residents sampled by a multi-stage random approach, data were collected and blood specimens were screened for anti-Ov16 IgG4 using the SD BIOLINE Onchocerciasis IgG4 rapid tests. The study revealed an overall anti-Ov16 IgG4 rate of 18.5% (94/508) in all surveyed districts, with 10.2% (12/118) of children aged ≤10 years being seropositive. Moreover, rates of 8.0% (4/50) and 6.1% (4/66) were found in districts not officially listed as endemic for the disease. Multivariable analysis confirmed the age of more than ten years and residing within a large family as the independent predictors of exposure to infection. CONCLUSIONS/SIGNIFICANCE: Onchocerciasis transmission is still ongoing as supported by the higher anti-Ov16 IgG4 seroprevalence rate among children aged ≤10 years compared to that (<0.1%) previously set by the World Health Organization as a serologic criterion for transmission interruption. Further large-scale studies combining serologic and entomologic criteria are recommended for the mapping of O. volvulus in human and blackfly populations in endemic foci and their neighboring areas of uncertain endemicity. In addition, ivermectin distribution, coverage and impact on disease transmission need to be continually assessed.

A community-based survey of Toxoplasma gondii infection among pregnant women in rural areas of Taiz governorate, Yemen: the risk of waterborne transmission.

BACKGROUND: Toxoplasma gondii is a zoonotic coccidian parasite causing morbidity and mortality. In Yemen, T. gondii infection has been reported among pregnant women seeking healthcare in the main cities. However, no data are available on the prevalence of T. gondii infection and its associated risk factors among pregnant women in the rural communities of the country. Thus, the present study aimed to determine the seroprevalence of T. gondii and identify its risk factors among pregnant women in the rural communities of Taiz governorate, Yemen. METHODS: A total of 359 pregnant women living in the rural communities of Taiz governorate were enrolled in this study by house-to-house visits. Data were collected using a pre-designed questionnaire, and blood samples were collected and tested for the detection of anti- T. gondii IgM and IgG antibodies by enzyme-linked immunosorbent assay. RESULTS: The prevalence of T. gondii infection among pregnant women in this study was 46.2% (166/359). Bivariate analysis identified the age of ≥ 30 years (odds ratio [OR] = 1.7; 95% confidence interval [CI] = 1.09-2.65, P = 0.019) and unimproved water sources (OR = 2.2; 95% CI = 1.10-4.55, P = 0.023) as factors associated with T. gondii infection among pregnant women. The multivariable analysis, however, identified unimproved water sources as an independent risk factor (adjusted OR = 2.4; 95% CI = 1.16-5.0, P = 0.018) associated with T. gondii infection among pregnant women. CONCLUSIONS: Pregnant women in the rural communities of Taiz, Yemen are at high risk of contracting T. gondii infection. Unimproved water sources (wells, water streams and water tanks) are significantly associated with T. gondii infection and should be considered in prevention and control strategies, especially among pregnant women.

Toxoplasma gondii infection among pregnant women in Yemen: Factors associated with high seroprevalence.

INTRODUCTION: Although toxoplasmosis is an important public health problem, there is scarcity of data on the disease available from Yemen. A cross-sectional survey was conducted in health facilities to determine seroprevalence of Toxoplasma gondii and associated risk factors among pregnant women in Sana'a, the capital city of Yemen. METHODOLOGY: A total of 593 pregnant women were included and examined for anti-T. gondii antibodies (Ab) using enzyme-linked immunosorbent assay. Bio and socio-demographic data were collected by pre-tested structured questionnaires through face-to-face interviews. RESULTS: The overall seroprevalence of T. gondii was 45.4% (95% confidence interval: 41%-49%). The prevalence of anti-T. gondii IgG and IgM was 43.7 (95% CI: 40-%48%) and 9.1% (95% CI: 7%-12%), respectively. About 7.4 (95% CI: 6%-10%) of pregnant women were seropositive for both IgG and IgM Abs. Multivariate logistic regression analysis identified the following risk factors for toxplasmosis (IgG and/or IgM): age ≥ 25 years (adjusted OR: 2.02, 95% CI: 1.44-2.84, p < 0.001), rearing cats in the house (OR: 1.75, 95% CI: 1.20-2.55, p = 0.004), and contact with soil (OR: 1.90, 95% CI: 1.32-2.75, p = 0.001). CONCLUSIONS: The study reported high seroprevalence among pregnant women in Sana'a, Yemen, with a high proportion of pregnant women having a possibility of acute toxoplasmosis. This highlights the need for including routine screening for T. gondii in pregnant women in the country's antenatal clinics. In addition, health education on the mode of transmission of toxoplasmosis should be provided for pregnant women in Yemen.

School-based prevalence of intestinal parasitic infections and associated risk factors in rural communities of Sana'a, Yemen.

Yemen is a developing country overwhelmed with a triad of poverty, diseases and social conflicts. Moreover, the majority of its population live in rural communities and suffer from intestinal parasitic infections (IPIs). Therefore, the present school-based, cross-sectional survey aimed to detect the prevalence of such infections and associated risk factors among schoolchildren in the rural communities of Bani Alharith, Hamdan and Bani Hushaysh districts of Sana'a, north of Yemen. Socio-demographic data and certain behavioral risk factors as well as stool samples were collected from 1218 schoolchildren from ten randomly schools in the study area. Fresh stool samples were examined for parasites by direct saline and iodine preparations and after concentration with formol-ether technique. The overall prevalence of IPIs was 54.8%, with a higher frequency of protozoal than helminthic infections (37.6 vs. 17.2%, respectively). Parasite species recovered were Entameba histolytica (21.5%), Giardia lamblia (16.1%), Ascaris lumbricoides (8.3%), Hymenolepis nana (5.3%), Schistosoma mansoni (2.6%), Trichuris trichiura (0.5%) and Enterobius vermicularis (0.4%). Univariate analysis showed that the male gender and illiteracy of fathers and/or mothers were the socio-demographic factors significantly associated with higher infection rates. The illiteracy of mothers was also confirmed as an independent risk factor by multivariable analysis. On the other hand, not washing hands before eating, not washing fruits and vegetables before consumption, eating uncovered food and not clipping fingernails were the risk behaviors significantly associated with higher infection rates, with the last three ones being confirmed as independent risk factors. Therefore, control measures should include regular treatment of protozoal infections and deworming of schoolchildren, promotion of hygiene in rural schools through health education programs, regular inspection of schoolchildren for personal hygiene practices and the provision of a healthy school infrastructure.

First Molecular Characterization of Leishmania Species Causing Visceral Leishmaniasis among Children in Yemen.

Visceral leishmaniasis (VL) is a debilitating, often fatal disease caused by Leishmania donovani complex; however, it is a neglected tropical disease. L. donovani complex comprises two closely related species, L. donovani that is mostly anthroponotic and L. infantum that is zoonotic. Differentiation between these two species is critical due to the differences in their epidemiology and pathology. However, they cannot be differentiated morphologically, and their speciation using isoenzyme-based methods poses a difficult task and may be unreliable. Molecular characterization is now the most reliable method to differentiate between them and to determine their phylogenetic relationships. The present study aims to characterize Leishmania species isolated from bone marrows of Yemeni pediatric patients using sequence analysis of the ribosomal internal transcribed spacer-1 (ITS1) gene. Out of 41 isolates from Giemsa-stained bone marrow smears, 25 isolates were successfully amplified by nested polymerase chain reaction and sequenced in both directions. Phylogenetic analysis using neighbor joining method placed all study isolates in one cluster with L. donovani complex (99% bootstrap). The analysis of ITS1 for microsatellite repeat numbers identified L. infantum in 11 isolates and L. donovani in 14 isolates. These data suggest the possibility of both anthroponotic and zoonotic transmission of VL-causing Leishmania species in Yemen. Exploring the possible animal reservoir hosts is therefore needed for effective control to be achieved.