To a large extent, the development and cellular function of any organism are controlled by genes. A gene is the functional unit of inheritance controlling the transmission and expression of one or more traits. The gene is made from a DNA molecule which is copied and inherited across generations and from RNAs that code for a polypeptide or for a RNA chain that has a function in the organism. Gene mutation is a change in DNA nucleotide sequence of a short region of a genome. Alteration in DNA sequence affects all copies of the encoded protein resulting in structural and functional changes or decrease or complete expression loss of the encoded protein. Gene mutation may occur in either the parasite or the host, which may be beneficial or harmful for each. All through this review, the authors will focus on host or parasite gene mutations (causes and types) and their relation(s) to or effect(s) on parasitic diseases. The review presents examples of gene mutations in the host (part I) or parasite (part II) focusing on disease susceptibility or resistance, drug resistance encountered in several parasitic diseases, carcinogenesis, virulence, pathogenesis, and clinical outcome as well as their relations with insecticide resistance and vector control. Abbreviations: CM: Cerebral malaria, G6PD: Glucose-6-phosphate dehydrogenase; MBL: Mannose-binding lectin; mdr: Multi-drug resistance gene; NO: Nitric oxide; SNP: Single-nucleotide polymorphism; VL: Visceral leishmaniasis.

Background Trichomonas vaginalis is the etiological parasite of trichomoniasis. Endosymbiotic Mycoplasma hominis can exist in T. vaginalis populations. However, its consequences are not yet known. Recently, T. vaginalis isolates positive for M. hominis as proven by PCR had greater cytopathic effects on human vaginal epithelial cells and also on Madin–Darby canine kidney cells in vitro. Objective This study aimed to detect the presence of M. hominis infecting Egyptian T. vaginalis isolates and to evaluate the pathogenicity of this association in vivo. Patients and methods Forty-five symptomatic and asymptomatic T. vaginalis isolates were obtained from Suez Canal and General Hospitals, Ismailia city, Egypt. All isolates were axenically cultivated in Diamond’s TYM medium, followed by DNA extraction and PCR using primer pair targeting 16S rRNA gene to detect M. hominis-infected isolates. Positive M. hominis PCR products were subjected to sequencing analysis. All isolates were experimentally inoculated intravaginally in female albino mice to assess the pathogenicity of different isolates. Results The detection rate of M. hominis-positive T. vaginalis isolates was 20% as determined with PCR. No statistically significant association was recorded between M. hominis-infected T. vaginalis among symptomatic and asymptomatic isolates. Experimental mice infection showed varying degrees of inflammation by the different isolates. Conclusion To our knowledge, this study is the first report of T. vaginalis infection by M. hominis among Egyptian isolates and it was deduced that the association of M. hominis and T. vaginalis does not affect the clinical presentation of vaginal trichomoniasis and does not cause enhanced pathological changes in infected mice.

Background Techniques used to diagnose Acanthamoeba keratitis (AK), a sight-threatening corneal infection, are either insensitive or time-consuming. Early and accurate diagnosis and appropriate therapy are the key to a good prognosis. Objective The objective of this study is to shed light on the efficacy of PCR in the diagnosis of AK in comparison with other diagnostic techniques. Patients and methods Corneal swabs and scrapings from 95 cases suspected to have AK were examined by microscopy, culture on non-nutrient agar seeded with the avian fecal Escherichia coli AFEC49, and by PCR targeting the 18S rRNA gene. Results The highest number of positive swabs and scrapings was detected by the PCR technique (5.26 and 27.37%, respectively), followed by culture (1.05 and 13.68%, respectively), and the lowest was detected by direct microscopy (0 and 7.37%, respectively). Corneal scrapings showed more positive cases than corneal swabs with statistically significant differences irrespective of the technique used. PCR results were significant versus culture (P<0.05) and direct microscopy (P<0.001). Out of the 26 positive cases, 20 were contact lens wearers, 13 were swimming pools users, five had a history of eye trauma, and five had undergone previous eye operation. Conclusion PCR proved to be a better technique for the detection of Acanthamoeba infection compared with direct microscopy and culture techniques. Scrape specimens are more efficient than swabs in detecting Acanthamoeba by different diagnostic techniques. The important risk factors of AK were contact lens wearers, use of swimming pools, a history of previous eye operation as well as eye trauma.

Background Malaria has been documented as a major health problem in Saudi Arabia, and it is highly endemic especially in the Southwest (Jazan and Asir). Its control is considered a challenge; hence proper diagnosis is essential for implementation of successful control programs. Accordingly, the diagnostic test used should be easy, rapid, and reliable, besides it must be accurate and cost effective. Objective This work aims to study reliability and diagnostic accuracy of an immunochromatographic test (ICT) using BinaxNOW^® malaria test compared to microscopical examination of blood film as gold standard for malaria diagnosis among clinically suspected patients in Jazan area, KSA. Methods A cross sectional prospective designed study was done for 200 patients with prolonged fever attending Jazan general hospitals. Venous blood samples were collected for both microscopic examination of Giemsa-stained thick and thin blood and rapid ICT (BinaxNOW^®). Results Microscopic examination of Giemsa-stained blood smears revealed 64 out of 200 cases (32%) positive for Plasmodium spp.; 43 out of 64 (67.2%) were positive for P. falciparum; 12 (18.7%) had mixed infection including P. falciparum; and 9 (14.1%) belonged to other Plasmodium spp. of which 8 (12.5%) were P. vivax and one case (1.6%) was P. ovale. ICT showed 66 out of 200 (33%) cases with positive results for Plasmodium spp. and one sample gave an invalid result. The overall sensitivity and specificity of ICT were 97% and 96%, respectively. While for single P. falciparum infection sensitivity and specificity were 96.7% and 78%, respectively. Regarding Plasmodium spp. other than P. falciparum sensitivity was 91.6% and specificity was 100%. Conclusion The use of ICT complement to microscopy is of great value particularly in Jazan, KSA, where P. falciparum and P. vivax are the most prevalent Plasmodium spp. These methods help in expanding laboratory based diagnosis, and minimize malaria associated morbidity and mortality.

Background Malaria is one of the major public health problems in India. The majority of cases are because of Plasmodium falciparum. A sudden increase in chloroquine (CQ) resistance in P. falciparum cases has been noted. Of the various genetic alteration genes known, Pfmdr1 has been shown to be associated with CQ resistance. Point mutations in the Pfmdr1 gene at several positions result in amino acid changes associated with CQ resistance. The mutation in codon 86 (from asparagine to tyrosine, N86Y) appears to be the most important. Objective The aim of this study is to determine the prevalence of polymorphisms at position 86 of the Pfmdr1 gene among patients not responding to CQ therapy. Materials and methods Blood samples of known P. falciparum cases not responding to CQ treatment were collected. DNA was isolated according to the manufacturer’s instructions. Nested PCR was performed to amplify the Pfmdr1 gene using commercially obtained primers. The finally amplified product was subjected to restriction digestion with AflIII (mutational allele) and ApoI (wild-type allele). The digests were resolved on a 3% agarose gel and stained with ethidium bromide. Results A total of 25 P. falciparum isolates from patients not responding to CQ therapy were used in the study. Polymorphism was determined successfully in 16 isolates and classified as mutant-type Y86 (16) and wild-type N86 (9). Conclusion A strong association was observed between point mutations in the Pfmdr1 gene, codon 86, and in vivo CQ resistance in these isolates.

Cysticercosis is a parasitic disease caused by the larval form of the cestode worm Taenia solium. It is commonly manifested as subcutaneous, intramuscular, eye, or brain nodules. We report two cases in an 8-year-old male child who presented with a cheek nodule, and another in a 25-year-old man who presented with a flank swelling. Both cases were diagnosed by fine-needle aspiration cytology. The use of fine-needle aspiration cytology highlights the cytomorphological diagnosis of cysticercosis in subcutaneous and intramuscular nodules.

Hydatid disease is caused by Echinococcus granulosus, and the commonly affected organs are the liver and lung. The musculoskeletal or soft tissue involvement accounts for about 0.5–5% of all cases in endemic areas. This case report indicates that hydatid cyst should be considered in the differential diagnosis of benign cystic swelling in the head and neck region. We report this case of a 32-year-old female patient with an unusual presentation of a swelling in the deeper plane of the sternocleidomastoid muscle in the neck and diagnosed by means of fine needle aspiration cytology.