BackgroundToxoplasmosis is a disease caused by Toxoplasma gondii and at least one-third of the world’s population has detectable T. gondii antibodies. The seroprevalence of T.gondii ranges from 15% to 50% among the Mexican general population. The aim of this work was to determine the mean prevalence and weighted mean prevalence of T. gondii infection, and to evaluate the epidemiological transition of infection in Mexico.MethodsPub Med, Lilacs, Medline, Latindex, Google Scholar data bases were searched to retrieve reports from 1951 up to 2012 regarding prevalence data, diagnostic tests and risk factors of infection among the adult population. Data collection and criteria eligibility was established in order to determine the crude prevalence (proportion of positive cases) of each study, together with weighted population prevalence according to individual research group categories to limit the bias that may impose the heterogeneous nature of the reports. A Forest Plot chart and linear regression analysis were performed by plotting the prevalence of infection reported from each study over a period of sixty years.ResultsA total of 132 studies were collected from 41 publications that included 70,123 individuals. The average mean prevalence was 27.97%, and weighted mean prevalence was 19.27%. Comparisons among different risk groups showed that the weighted prevalence was higher in women with miscarriages (36.03%), immunocompromised patients (28.54%), mentally-ill patients (38.52%) and other risk groups (35.13%). Toxoplasma infection among the Mexican population showed a downward trend of 0.1%/year over a period of sixty years that represents a 5.8% reduction in prevalence.ConclusionsThis analysis showed a downward trend of infection; however, there are individuals at high risk for infection such as immunocompromised patients, mentally-ill patients and pregnant women. Further research is required to provide better prevention strategies, effective diagnostic testing and medical management of patients. Educational efforts are required to avoid the transmission of infection in populations that cannot be controlled by drugs alone.

We read with interest the article by Ben-Tal and coworkers 1 who reported that concentrations of prothrombin, Factor (F) VII, F IX, FX, and fibrinogen remained stable in plasma that had been twice-frozen and stored at -80 ∞ C. These data support their conclusion that this component can be used safely for transfusion as a source of vitamin K-dependent clotting factors and fibrinogen, but do not provide information on the use of this component for replacing protein C, protein S, or antithrombin III. We performed the following study to provide data on the stability of these proteins in twice-frozen fresh frozen plasma (FFP).Ten units of FFP were prepared from whole blood collected in citrate phosphate dextrose (Macopharma, Mouvaux, France). The units were thawed and 5-mL aliquots were removed by sterile technique (first thaw, Time 0). Concentrations of protein C, protein S, and antithrombin III were measured using a coagulation analyzer (IL Futura, Instrumentation Laboratory, Warrington, UK). The thawed units were stored at 4 ∞ C for 24 hours, and another sample was obtained (first thaw, Time 24). The units were refrozen at -80 ∞ C for 1 week, and a third sample was obtained immediately after thawing (second thaw, Time 0) and a fourth sample 24 hours later (second thaw, Time 24).The results of factor measurements (Table 1) show that although there are individual variations in the plasma concentrations of protein C, protein S, and fibrinogen among normal blood donors, these proteins remain stable after two thaws and storage at 4 ∞ C for two 24-hour periods. We believe that these findings complement those of Ben-Tal and colleagues, indicating that twice-frozen and thawed plasma is suitable not only for replacing vitamin K-dependent coagulation factors, but also for replacing protein C, protein S, and antithrombin. Also, using twicefrozen and thawed plasma may significantly reduce wastage of thawed and unused FFP. Muttuswamy Sivakumaran, MSc, FRCP, FRCPath, PhD

We retrospectively studied 'biopsy sp eciniens obtained fro m 16 pati ents who had carcinoma of the tonsil or nasopha rynx. Polytnerase chaiil reaction testing detected the presence of human papilloina viru s (HPV) iil 13 samp les (81.3%)-six tonsi llar and se ven nas opharyngeal. Eleven of the 13 positive samples (84.6%) com ained HP V subtype 31. We believe that this is the firs t report of the pre sence of HPV subtype 31 iil these carc inonias. Iil addition to the significant association between tons illar and nasopharyngeal ealleer and HP V, our analysis of descriptive variables confin ned the association betweeu the incidenee of these neopla sms and poor oral hygi ene and loll' socioeconotnic status iil older adults.

Intestinal parasites in Mexico are an endemic problem. A study was conducted in children, teenagers and adults in a rural community in Colima, Mexico to examine the prevalence and intensity of Ascaris lumbricoides infection and to evaluate the parasitological and clinical efficacy of nitazoxanide (NTZ). Two hundred and eighty children, teenagers and adults participated in this study. Parasitological diagnosis from faeces was confirmed by three consecutive stool samples using the floatation concentration Faust method. Egg counts were performed as described by the Kato-Katz technique before and after treatment. A questionnaire was systematically applied to obtain information about socio-economic status and hygienic habits. One hundred and six participants (38%) were diagnosed as harbouring intestinal parasites, and 86 of them (81%) were infected with A. lumbricoides. All patients with ascariasis infections underwent a complete physical examination before and after NTZ treatment. NTZ resolved 88% of the ascariasis cases, with a 89% clinical efficacy, and there was a 97.5% reduction in the levels of morbidity. The most intense infections for A. lumbricoides were found in housewives, and statistically significant associations were found between ascariasis and the absence of drainage and living in houses with dirt floors.

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