Susceptibility of wild and colonized Anopheles stephensi to Plasmodium vivax infection.

BACKGROUND: As much as 80% of global Plasmodium vivax infections occur in South Asia and there is a shortage of direct studies on infectivity of P. vivax in Anopheles stephensi, the most common urban mosquito carrying human malaria. In this quest, the possible effects of laboratory colonization of mosquitoes on infectivity and development of P. vivax is of interest given that colonized mosquitoes can be genetically less divergent than the field population from which they originated. METHODS: Patient-derived P. vivax infected blood was fed to age-matched wild and colonized An. stephensi. Such a comparison requires coordinated availability of same-age wild and colonized mosquito populations. Here, P. vivax infection are studied in colonized An. stephensi in their 66th-86th generation and fresh field-caught An. stephensi. Wild mosquitoes were caught as larvae and pupae and allowed to develop into adult mosquitoes in the insectary. Parasite development to oocyst and sporozoite stages were assessed on days 7/8 and 12/13, respectively. RESULTS: While there were batch to batch variations in infectivity of individual patient-derived P. vivax samples, both wild and colonized An. stephensi were roughly equally susceptible to oocyst stage Plasmodium infection. At the level of sporozoite development, significantly more mosquitoes with sporozoite load of 4+ were seen in wild than in colonized populations.

Dynamics of Plasmodium vivax sporogony in wild Anopheles stephensi in a malaria-endemic region of Western India.

BACKGROUND: In global efforts to track mosquito infectivity and parasite elimination, controlled mosquito-feeding experiments can help in understanding the dynamics of parasite development in vectors. Anopheles stephensi is often accepted as the major urban malaria vector that transmits Plasmodium in Goa and elsewhere in South Asia. However, much needs to be learned about the interactions of Plasmodium vivax with An. stephensi. As a component of the US NIH International Center of Excellence for Malaria Research (ICEMR) for Malaria Evolution in South Asia (MESA), a series of membrane-feeding experiments with wild An. stephensi and P. vivax were carried out to better understand this vector-parasite interaction. METHODS: Wild An. stephensi larvae and pupae were collected from curing water in construction sites in the city of Ponda, Goa, India. The larvae and pupae were reared at the MESA ICEMR insectary within the National Institute of Malaria Research (NIMR) field unit in Goa until they emerged into adult mosquitoes. Blood for membrane-feeding experiments was obtained from malaria patients at the local Goa Medical College and Hospital who volunteered for the study. Parasites were counted by Miller reticule technique and correlation between gametocytaemia/parasitaemia and successful mosquito infection was studied. RESULTS: A weak but significant correlation was found between patient blood gametocytaemia/parasitaemia and mosquito oocyst load. No correlation was observed between gametocytaemia/parasitaemia and oocyst infection rates, and between gametocyte sex ratio and oocyst load. When it came to development of the parasite in the mosquito, a strong positive correlation was observed between oocyst midgut levels and sporozoite infection rates, and between oocyst levels and salivary gland sporozoite loads. Kinetic studies showed that sporozoites appeared in the salivary gland as early as day 7, post-infection. CONCLUSIONS: This is the first study in India to carry out membrane-feeding experiments with wild An. stephensi and P. vivax. A wide range of mosquito infection loads and infection rates were observed, pointing to a strong interplay between parasite, vector and human factors. Most of the present observations are in agreement with feeding experiments conducted with P. vivax elsewhere in the world.

Comparative effect of progressive relaxation technique and Benson's technique on anxiety and fatigue in cancer survivors - an experimental study.

BACKGROUND AND PURPOSE: Anxiety and fatigue is a common symptom that is seen in cancer survivors, who have recently been diagnosed as well as those who are undergoing chemotherapy and radiation therapy as they are emotionally distressed. Progressive relaxation technique and Benson's relaxation is seen to be efficacious in lowering anxiety and fatigue in cancer survivors as individual treatment. To compare the depiction of progressive relaxation technique and Benson's technique on anxiety using Hamilton anxiety scale (HAM-A), blood pressure (BP) and heart rate (HR), and fatigue using cancer fatigue scale (CFS). MATERIALS AND METHODS: A randomized clinical trial (chit method) was carried out on 42 subjects with cancer related anxiety and fatigue. Subjects were randomly allotted to Group A and Group B. Group A was administered Progressive relaxation technique. Group B was administered Benson's technique. Primary outcome measures used were Hamilton Anxiety Scale and Cancer fatigue scale, secondary outcome measures were HR and BP. Outcomes were evaluated at baseline, immediate and after 5 days of the treatment. RESULTS: The results were analyzed using independent t test for comparing the 2 groups. On comparing group, A and B for baseline to immediate and baseline to after 5 days, using HAM-A, BP, HR, CFS, no statistical significance was found. Whereas within group analysis (within group A and B) showed significant reduction in anxiety and fatigue in cancer survivors, with a P value significant at <0.05 as seen from baseline to immediate and baseline to 5 days, with 0.7 effect size. CONCLUSION: The study concludes that both Progressive relaxation technique and Benson's technique are equally effective in reducing anxiety and PRT lowers fatigue more effectively than Benson's technique in cancer survivors.