Susceptibility of Anopheles gambiae from Côte d'Ivoire to insecticides used on insecticide-treated nets: evaluating the additional entomological impact of piperonyl butoxide and chlorfenapyr.

BACKGROUND: Pyrethroid-treated mosquito nets are currently the mainstay of vector control in Côte d'Ivoire. However, resistance to pyrethroids has been reported across the country, limiting options for insecticide resistance management due to the paucity of alternative insecticides. Two types of insecticide-treated nets (ITNs), ITNs with pyrethroids and the synergist piperonyl butoxide (PBO), and Interceptor®G2 nets, a net treated with a combination of chlorfenapyr and alpha-cypermethrin, are believed to help in the control of pyrethroid-resistant mosquitoes. METHODS: The susceptibility of Anopheles gambiae sensu lato (s.l.) to pyrethroid insecticides with and without pre-exposure to PBO as well as to chlorfenapyr was investigated in fifteen sites across the country. Susceptibility tests were conducted on 2- to 4-day old adult female An. gambiae s.l. reared from larval collections. The resistance status, intensity, and effects of PBO on mortality after exposure to different concentrations of deltamethrin, permethrin and alpha-cypermethrin were determined using WHO susceptibility test kits. In the absence of a WHO-recommended standard protocol for chlorfenapyr, two interim doses (100 and 200 µg/bottle) were used to test the susceptibility of mosquitoes using the CDC bottle assay method. RESULTS: Pre-exposure to PBO did not result in full restoration of susceptibility to any of the three pyrethroids for the An. gambiae s.l. populations from any of the sites surveyed. However, PBO pre-exposure did increase mortality for all three pyrethroids, particularly deltamethrin (from 4.4 to 48.9%). Anopheles gambiae s.l. from only one site (Bettie) were susceptible to chlorfenapyr at the dose of 100 µg active ingredient (a.i.)/bottle. At the dose of 200 µg (a.i.)/bottle, susceptibility was only recorded in 10 of the 15 sites. CONCLUSION: Low mosquito mortality was found for pyrethroids alone, and while PBO increased mortality, it did not restore full susceptibility. The vector was not fully susceptible to chlorfenapyr in one third of the sites tested. However, vector susceptibility to chlorfenapyr seems to be considerably higher than for pyrethroids alone or with PBO. These data should be used cautiously when making ITN procurement decisions, noting that bioassays are conducted in controlled conditions and may not fully represent field efficacy where the host-seeking behaviours, which include free-flying activity are known to enhance pro-insecticide chlorfenapyr intoxication to mosquitoes.

Surveillance Training for Ebola Preparedness in Côte d'Ivoire, Guinea-Bissau, Senegal, and Mali.

The 2014-2015 epidemic of Ebola virus disease in West Africa primarily affected Guinea, Liberia, and Sierra Leone. Several countries, including Mali, Nigeria, and Senegal, experienced Ebola importations. Realizing the importance of a trained field epidemiology workforce in neighboring countries to respond to Ebola importations, the Centers for Disease Control and Prevention Field Epidemiology Training Program unit implemented the Surveillance Training for Ebola Preparedness (STEP) initiative. STEP was a mentored, competency-based initiative to rapidly build up surveillance capacity along the borders of the at-risk neighboring countries Côte d'Ivoire, Mali, Senegal, and Guinea-Bissau. The target audience was district surveillance officers. STEP was delivered to 185 participants from 72 health units (districts or regions). Timeliness of reporting and the quality of surveillance analyses improved 3 months after training. STEP demonstrated that mentored, competency-based training, where learners attain competencies while delivering essential public health services, can be successfully implemented in an emergency response setting.

Assessing and mitigating the risks for polio outbreaks in polio-free countries - Africa, 2013-2014.

Since 1988, when the Global Polio Eradication Initiative (GPEI) began, the annual number of polio cases has decreased by >99%. Only three countries remain that have never interrupted wild poliovirus (WPV) transmission: Afghanistan, Nigeria, and Pakistan. Since 2001, outbreaks have occurred in 31 formerly polio-free counties in Africa, with outbreaks in 25 countries caused by WPV originating in Nigeria (2-4). After the declaration of the World Health Assembly of polio eradication as a programmatic emergency in 2012, efforts to identify areas at high risk for importation-associated outbreaks and to reduce that risk have been intensified. This report updates the 2013 assessment of the risk for outbreaks attributable to importation of poliovirus in 33 countries in Africa, using indicators of childhood susceptibility to poliovirus and proximity to countries currently affected by polio . From January 2013 to August 12, 2014, outbreaks occurred in five African countries. Four of the five (Cameroon, Equatorial Guinea, Ethiopia, and Somalia) have had recent transmission (cases within the previous 12 months). Based on the current risk assessment, 15 countries are considered to be at high risk for WPV outbreaks, five at moderate-to-high risk, seven at moderate risk, and six at low risk. In 15 of the 33 countries, less than half of the population resides in areas where surveillance performance indicators have met minimum targets. Enhanced, coordinated activities to raise childhood immunity are underway in 2014 to prevent additional WPV spread. Although substantial progress toward polio eradication has occurred in Nigeria, all African countries remain at risk for outbreaks as long as WPV continues to circulate anywhere on the continent.

Transmission network analysis to complement routine tuberculosis contact investigations.

OBJECTIVE: We examined the feasibility and value of network analysis to complement routine tuberculosis (TB) contact investigation procedures during an outbreak. METHODS: We reviewed hospital, health department, and jail records and interviewed TB patients. Mycobacterium tuberculosis isolates were genotyped. We evaluated contacts of TB patients for latent TB infection (LTBI) and TB, and analyzed routine contact investigation data, including tuberculin skin test (TST) results. Outcomes included number of contacts identified, number of contacts evaluated, and their TST status. We used network analysis visualizations and metrics (reach, degree, betweenness) to characterize the outbreak. RESULTS: secondary TB patients and more than 1200 contacts. Genotyping detected a 21-band pattern of a strain W variant. No HIV-infected patients were diagnosed. Contacts prioritized by network analysis were more likely to have LTBI than nonprioritized contacts (odds ratio=7.8; 95% confidence interval=1.6, 36.6). Network visualizations and metrics highlighted patients central to sustaining the outbreak and helped prioritize contacts for evaluation. CONCLUSIONS: A network-informed approach to TB contact investigations provided a novel means to examine large quantities of data and helped focus TB control.