Uncomplicated falciparum malaria among schoolchildren in Bajil district of Hodeidah governorate, west of Yemen: association with anaemia and underweight.

BACKGROUND: Malaria, malnutrition and anaemia are major public health problems in Yemen, with Hodeidah being the most malaria-afflicted governorate. To address the lack of relevant studies, this study was conducted to determine the prevalence of Plasmodium falciparum and its relation to nutritional status and haematological indices among schoolchildren in Bajil district of Hodeidah governorate, west of Yemen. METHODS: A cross-sectional study was conducted among 400 schoolchildren selected randomly from four schools in Bajil district. Data about demographic characteristics, risk factors and anthropometric measurements of age, height and weight were collected. Duplicate thick and thin blood films were prepared, stained with Giemsa and examined microscopically for malaria parasites. The density of P. falciparum asexual stages was estimated on thick films. EDTA-blood samples were examined for the haematological indices of haemoglobin (Hb) and blood cell counts. RESULTS: Plasmodium falciparum was prevalent among 8.0% (32/400) of schoolchildren with a mean parasite density of 244.3 ± 299.3/µL of blood and most infections showing low-level parasitaemia, whereas Plasmodium vivax was detected in one child (0.25%). Residing near water collections was a significant independent predictor of falciparum malaria [adjusted odds ratio (AOR) = 2.6, 95.0% CI 1.20-5.72; p = 0.016] in schoolchildren. Mild anaemia was prevalent among more than half of P. falciparum-infected schoolchildren and significantly associated with falciparum malaria (AOR = 5.8, 95.0% CI 2.39-14.17; p < 0.001), with a mean Hb concentration of 10.7 ± 1.0 g/dL. Although the mean values of the total white blood cells, monocytes and platelets were significantly lower in infected than non-infected schoolchildren, they were within normal ranges. More than half of the children were malnourished, with stunting (39.3%) and underweight (36.0%) being the most prevalent forms of malnutrition; 6.3% of children were wasted. Underweight (AOR = 5.3, 95.0% CI 2.09-13.62; p < 0.001) but not stunting or wasting, was a significant predictor of falciparum malaria among schoolchildren. CONCLUSION: Asymptomatic falciparum malaria is prevalent among schoolchildren in Bajil district of Hodeidah Governorate, with predominance of low parasitaemic infections and significant association with mild anaemia and underweight. Residence near water collection is a significant predictor of infection with falciparum malaria among schoolchildren. Further studies among children with severe malaria and those with high parasite densities are recommended.

Intestinal parasitoses and schistosome infections among students with special reference to praziquantel efficacy in patients with schistosomosis in Hajjah governorate, Yemen

The majority of the population in Yemen lives in rural areas and suffers from parasitic infections. Therefore, the present study aimed to determine the prevalence of intestinal parasitoses and schistosome infections among the students enrolled in the primary schools in Hajjah governorate ­ north of Yemen, along with an assessment of praziquantel (PZQ) in the treatment of microscopy-confirmed cases of Schistosoma mansoni and Schistosoma haematobium. For this purpose, 780 samples (320 stool and 460 urine) were examined microscopically. The present study revealed an overall infection rate of 75.3% (241/320) with intestinal parasites and Schistosoma mansoni. The detected parasite species included Entamoeba histolytica (27.8%), Hymenolepis nana (12.2%), Giardia lamblia (9.7%), Entamoeba coli (9.4%), S. mansoni (9.1%), Ascaris lumbricoides (6.9%), Trichuris trichiura (3.1%), Enterobius vermicularis (2.8%) and Ancylostoma duodenale (2.2%). Schistosoma haematobium was prevalent among 1.7% (8/460) of the investigated students. On the other hand, PZQ yielded a cure rate of 75.7% of Schistosoma-infected students when administered at 40 mg/kg body weight. However, a 100% cure rate was achieved when administered at 60 mg/kg body weight. Therefore, the findings of the present study highlight the importance of monitoring PZQ efficacy through large-scale studies in different settings endemic for schistosomosis in the country.

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.

Evaluation of rapid PfHRP-2/pLDH-based tests in diagnosing microscopy-confirmed falciparum malaria in Hodeidah governorate, Yemen.

Along with the determination of malaria infection rate among suspected patients attending hospitals in Hodeidah governorate, the present study evaluated the accuracy of Plasmodium falciparum histidine-rich protein-2 (PfHRP-2)/parasite-specific lactate dehydrogenase (pLDH)-based rapid diagnostic test (RDT) for the diagnosis of microscopy-confirmed falciparum malaria. An overall malaria infection rate of 19.3% (57/295) among suspected patients attending hospitals was microscopically confirmed. The sensitivity of thin blood films for the detection of malaria parasites was 79.0% compared to thick films and was greatly affected by the parasite density, being 65.0% or less at parasite densities of ≤1000 parasites/µl of blood. Compared to light microscopy, the present study revealed sensitivity levels of 100.0% (95% CI: 92.0-100.0) vs. 94.7% (95% CI: 84.2-98.6), specificity levels of 97.3% (95% CI: 89.8-99.5) vs. 100.0% (95% CI: 93.9-100.0), positive predictive values of 89.9% (95% CI: 88.3-99.0) vs. 100.0 (95% CI: 91.6-100.0) and negative predictive values of 100.0% (95% CI: 93.9-100.0) vs. 98.7% (95% CI: 89.3-98.7) for the PfHRP-2 and pLDH components of SD BIOLINE® RDT, respectively, for falciparum malaria diagnosis. Therefore, the overall accuracy levels of the PfHRP-2 and pLDH components of the investigated RDT for the diagnosis of microscopy-confirmed falciparum malaria are 98.5% (95% CI: 94.6-99.6) and 97.7% (95% CI: 93.5-99.2), respectively.

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.

Measuring resistant-genotype transmission of malaria parasites: challenges and prospects.

Increased gametocytemia in infections with resistant strains of Plasmodium species and their enhanced transmissibility are a matter of concern in planning and evaluating the impact of malaria control strategies. Various studies have determined weekly gametocyte carriage in response to antimalarial drugs in clinical trials. The advent of molecular biology techniques makes it easy to detect and quantify gametocytes, the stages responsible for transmission, and to detect resistant genotypes of the parasite. With the validation of molecular markers of resistance to certain antimalarial drugs, there is a need to devise a simpler formula that could be used with these epidemiological antimalarial resistance tools. Theoretical models for transmission of resistant malaria parasites are difficult to deploy in epidemiological studies. Therefore, devising a simple formula that determines the potential resistant-genotype transmission of malaria parasites should provide further insights into understanding the spread of drug resistance. The present perspective discusses gametocytogenesis in the context of antimalarial treatment and drug resistance. It also highlights the difficulties in applying the available theoretical models of drug resistance transmission and suggests Rashad's devised formula that could perhaps be used in determining potentially transmissible resistant genotypes as well as in mapping areas with high potential risk for the transmission of drug-resistant malaria. The suggested formula makes use of the data on gametocytes and resistant genotypes of malaria parasites, detected by molecular techniques in a certain geographical area within a particular point in time, to calculate the potential risk of resistant genotype transmission.

Cases of hydatidosis in patients referred to Governmental hospitals for cyst removal in Sana'a City, Republic of Yemen.

Hydatidosis is a parasitic infestation caused by Echinococcus granulosus. This disease is endemic in many countries including Yemen. The present review article aims to have a glimpse at the present status of hydatidosis in Yemen. This is the first descriptive study, investigating recorded cases of hydatidosis from the five main governmental hospitals in the capital Sana'a city, over a longer period starting from 2001 and ending in 2008. A total of 796 medical records of patients referred to the five main governmental hospitals in Sana'a city for cyst removal, were studied. Of these cases 482 were females and 314 were males. Their mean age was 30.0 ± 16.9 years. Information regarding the location of the cyst in the body, age, sex and residence of each patient was recorded. A higher infection rate was found in females than males (60.6% and 39.4%, respectively). Single organ involvement was observed in 98.6% cases, among which, the most frequent localizations were the liver (60.8%) followed by the lung (24.7%). Cases of hydatidosis appeared to increase during the period 2001-2008, with the lowest number (n=26) and the highest number (n=140) recorded in 2001 and 2007, respectively. We conclude that the risk of hydatidosis is still high in Yemen, where street or stray dogs move freely down town and the population should be aware about the role of dogs in the transmission of this disease. Hospital records provide a useful indication of infection expressed as annual rate of hospital cases. Finally, the collaboration of Public Health Authorities, the Veterinary Medical Authorities and the Environmental Affairs Authorities is a must to control this disease.

High frequency of Plasmodium falciparum chloroquine resistance marker (pfcrt T76 mutation) in Yemen: an urgent need to re-examine malaria drug policy.

BACKGROUND: Malaria remains a significant health problem in Yemen with Plasmodium falciparum being the predominant species which is responsible for 90% of the malaria cases. Despite serious concerns regarding increasing drug resistance, chloroquine is still used for the prevention and treatment of malaria in Yemen. This study was carried out to determine the prevalence of choloroquine resistance (CQR) of P. falciparum isolated from Yemen based on the pfcrt T76 mutation. METHODS: A cross-sectional study was carried out among 511 participants from four governorates in Yemen. Blood samples were screened using microscopic and species-specific nested PCR based on the 18S rRNA gene to detect and identify Plasmodium species. Blood samples positive for P. falciparum were used for detecting the pfcrt T76 mutation using nested-PCR. RESULTS: The prevalence of pfcrt T76 mutation was 81.5% (66 of 81 isolates). Coastal areas/foothills had higher prevalence of pfcrt T76 mutation compared to highland areas (90.5% vs 71.8%) (p = 0.031). The pfcrt T76 mutation had a significant association with parasitaemia (p = 0.045). Univariate analysis shows a significant association of pfcrt T76 mutation with people aged > 10 years (OR = 9, 95% CI = 2.3 - 36.2, p = 0.001), low household income (OR = 5, 95% CI = 1.3 - 19.5, p = 0.027), no insecticide spray (OR = 3.7, 95% CI = 1.16 - 11.86, p = 0.025) and not sleeping under insecticide treated nets (ITNs) (OR = 4.8, 95% CI = 1.38 - 16.78, p = 0.01). Logistic regression model confirmed age > 10 years and low household income as predictors of pfcrt T76 mutation in Yemen P. falciparum isolates. CONCLUSIONS: The high prevalence of pfcrt T76 mutation in Yemen could be a predictive marker for the prevalence of P. falciparum CQR. This finding shows the necessity for an in-vivo therapeutic efficacy test for CQ. P. falciparum CQR should be addressed in the national strategy to control malaria.

Molecular characterization of Leishmania species isolated from cutaneous leishmaniasis in Yemen.

BACKGROUND: Cutaneous leishmaniasis (CL) is a neglected tropical disease endemic in the tropics and subtropics with a global yearly incidence of 1.5 million. Although CL is the most common form of leishmaniasis, which is responsible for 60% of DALYs lost due to tropical-cluster diseases prevalent in Yemen, available information is very limited. METHODOLOGY/PRINCIPAL FINDINGS: This study was conducted to determine the molecular characterization of Leishmania species isolated from human cutaneous lesions in Yemen. Dermal scrapes were collected and examined for Leishmania amastigotes using the Giemsa staining technique. Amplification of the ribosomal internal transcribed spacer 1(ITS-1) gene was carried out using nested PCR and subsequent sequencing. The sequences from Leishmania isolates were subjected to phylogenetic analysis using the neighbor-joining and maximum parsimony methods. The trees identified Leishmania tropica from 16 isolates which were represented by two sequence types. CONCLUSIONS/SIGNIFICANCE: The predominance of the anthroponotic species (i.e. L. tropica) indicates the probability of anthroponotic transmission of cutaneous leishmaniasis in Yemen. These findings will help public health authorities to build an effective control strategy taking into consideration person-to-person transmission as the main dynamic of transmission of CL.

HLA class II alleles: susceptibility or resistance to cystic echinococcosis in Yemeni patients.

This is the first study dealing with the association between HLA alleles and cystic echinococcosis (CE) in Yemeni patients. The present study aimed to detect the association of HLA-DRB(1) alleles and susceptibility or resistance to CE in Yemeni patients by HLA-DRB(1) typing; first by HLA-DRB(1) amplification using PCR then using the allele-specific probing technique based on the reverse hybridization principle. This case-control study was carried out on 66 unrelated patients with confirmed CE and 66 apparently healthy individuals. The association of class II HLA-DRB alleles was examined in the patients with CE and compared with control subjects. Frequency of HLA-DR16 allele was 18.2% among patients and was statistically significant (higher) than in the control group [3%; odds ratio (OR) = 6.5, chi (2) = 7.1, P = 0.011]. Frequencies of HLA-DR1, DR8, and DR52 alleles were decreased in the patient group (0.0%, 0.0%, and 56%, respectively) than in the control group (19.7%, 9.1%, and 74.2%, respectively) (OR = 0.0, 0.0, 0.443 and P < 0.0001, 0.04, 0.05, respectively). HLA-DR16 allele was found to be statistically positively associated with the occurrence of isolated hepatic CE, single cysts, and cysts >5 cm in size. In contrast, HLA-DR1 and DR52 alleles were found to be statistically negatively associated with the occurrence of isolated hepatic CE. This study demonstrates that susceptibility to CE in Yemeni patients is statistically significantly associated with the HLA-DR16 allele and resistance to CE is statistically significantly associated with HLA-DR1, DR8, and DR52 alleles. Thus, this study has identified that carriers of HLA-DR16 are at high risk for CE, so appropriate preventive measures and quick and careful treatment should be applied to those patients.

Intestinal parasitosis among apparently healthy workers at restaurants of Sana'a City, Yemen.

A cross sectional study was conducted on randomly selected 303 apparently healthy workers in 58 restaurants in Sana'a City, with ages between 12 to 70 years 22.12 +/- 8.34). A required data were taken through a designed questionnaire and stool samples were collected and examined microscopically by direct wet mount (saline and iodine stained smears) and by formalin ether concentration sedimentation technique. The results showed 72.9% an overall infections rate In a descending order they were E. coli (58.85%), E. histolytica (48.87%), G. lamblia (35.29%), S. man-soni (7.69%), T. trichiura (4.98%), A. lumbricoides (4.07%), H. nana (3.62%), and 0.91% for both E. vermicularis and A. doudenale. Intervention programs including health education, strict supervision of health authorities on workers in restaurants, hotels and other food shops as well as environmental sanitation are required.

Cryptosporidiosis and other intestinal parasites in 3 Yemeni orphanages: prevalence, risk, and morbidity.

The epidemiological pattern of cryptosporidiosis and other intestinal parasites were studied among 3 orphanages in Sana'a City. A total of 292 orphans (225 males & 67 females), aged 4-20 years old were recruited. A questionnaire of demographic information, health status and other relevant information was filled out for each one. Fresh stool specimens were processed by wet mount preparation, formalin-ether concentration and MZL stain. Among 292 orphans, the overall parasitic rate was 62.7%. C. parvum showed highest prevalence (24%) followed by G. lamblia (16.8%), E. histolytica /E.dispar (13%), and then E. coli (18.5%). Hymenolepis nana was in 7.2% of children but only 3 cases of Ascaris lumbricoides. The risk of C. parvum was significantly higher in children < or = 10 years of age compared to older ones (OR = 3.86). The risk of other parasites did not differ significantly with orphans' age. Males showed 2.634 risk of C. parvum and 1.657 risk of G. lamblia compared to females with statistically significant difference. Bad personal hygiene was associated with higher risk of cryptosporidiosis (OR = 2.634, CI = 1.483-4.677) but the risk of other parasites was not significant. Diarrhea and abdominal pain were recorded in the three orphans, but without significance associated with parasites, either overall or for individual species but, A. lumbricoides was detected in 3 diarrheic children.

Anti-leishmanial polyclonal antibodies to assess the performance characteristics of leishmanial antigen detection ELISA.

The polyclonal antibodies raised in rabbits against amastigote antigen extract were purified and fractionated, and IgG class antibodies and from the same antibodies, a peroxidase conjugate (labeled antibodies) reagent were prepared. The antibodies and the labeled antibodies were analyzed for efficacy of the homologous extracted antigens by capture ELISA. The titration curves of the anti-amastigote IgG antibody against extracted antigens showed that both free antibody and corresponding labeled antibody reacted with the original amastigote antigens. Further analysis involved the interaction between the antibody and two leishmanial stages; mammalian amastigote & infective promasitgote by immunoflourescene technique. The strong interaction was not only with surface antigenic components of the stages but also with their internal components. Capture-ELISA system was done to detect specific leishmanial antigens in urine and sera from visceral leishmaniasis patients (VL). Most of the urine samples were positive (90% sensitivity) for leishmanial antigens without cross-reactivity (100% specificity) with any other tested samples from heterologous parasitic infections. But, only 61% sensitivity and 53% specificity were obtained when the capture ELISA was done to detect the specific leishmanail antigens in sera from VL.