Exploring HIV infection and susceptibility to measles among older children and adults in Malawi: a facility-based study

SummaryBackgroundHIV infection increases measles susceptibility in infants, but little is known about this relationship among older children and adults. We conducted a facility-based study to explore whether HIV status and/or CD4 count were associated with either measles seroprotection and/or measles antibody concentration.MethodsA convenience sample was recruited comprising HIV-infected patients presenting for follow-up care, and HIV-uninfected individuals presenting for HIV testing at Chiradzulu District Hospital, Malawi, from January to September 2012. We recorded age, sex, and reported measles vaccination and infection history. Blood samples were taken to determine the CD4 count and measles antibody concentration.ResultsOne thousand nine hundred and thirty-five participants were recruited (1434 HIV-infected and 501 HIV-uninfected). The majority of adults and approximately half the children were seroprotected against measles, with lower odds among HIV-infected children (adjusted odds ratio 0.27, 95% confidence interval 0.10–0.69; p=0.006), but not adults. Among HIV-infected participants, neither CD4 count (p=0.16) nor time on antiretroviral therapy (p=0.25) were associated with measles antibody concentration, while older age (p<0.001) and female sex (p<0.001) were independently associated with this measure.ConclusionsWe found no evidence that HIV infection contributes to the risk of measles infection among adults, but HIV-infected children (including at ages older than previously reported), were less likely to be seroprotected in this sample

Reaching Hard-to-Reach Individuals: Nonselective Versus Targeted Outbreak Response Vaccination for Measles

Current mass vaccination campaigns in measles outbreak response are nonselective with respect to the immune status of individuals. However, the heterogeneity in immunity, due to previous vaccination coverage or infection, may lead to potential bias of such campaigns toward those with previous high access to vaccination and may result in a lower-than-expected effective impact. During the 2010 measles outbreak in Malawi, only 3 of the 8 districts where vaccination occurred achieved a measureable effective campaign impact (i.e., a reduction in measles cases in the targeted age groups greater than that observed in nonvaccinated districts). Simulation models suggest that selective campaigns targeting hard-to-reach individuals are of greater benefit, particularly in highly vaccinated populations, even for low target coverage and with late implementation. However, the choice between targeted and nonselective campaigns should be context specific, achieving a reasonable balance of feasibility, cost, and expected impact. In addition, it is critical to develop operational strategies to identify and target hard-to-reach individuals

Measles in Democratic Republic of Congo: an outbreak description from Katanga, 2010--2011

BACKGROUND: The Democratic Republic of Congo experiences regular measles outbreaks. From September 2010, the number of suspected measles cases increased, especially in Katanga province, where Medecins sans Frontieres supported the Ministry of Health in responding to the outbreak by providing free treatment, reinforcing surveillance and implementing non-selective mass vaccination campaigns. Here, we describe the measles outbreak in Katanga province in 2010--2011 and the results of vaccine coverage surveys conducted after the mass campaigns. METHODS: The surveillance system was strengthened in 28 of the 67 health zones of the province and we conducted seven vaccination coverage surveys in 2011. RESULTS: The overall cumulative attack rate was 0.71% and the case fatality ratio was 1.40%.The attack rate was higher in children under 4 and decreased with age. This pattern was consistent across districts and time. The number of cases aged 10 years and older barely increased during the outbreak. CONCLUSIONS: Early investigation of the age distribution of cases is a key to understanding the epidemic, and should guide the vaccination of priority age groups

Drug-resistant tuberculosis in HIV-infected patients in a national referral hospital, Phnom Penh, Cambodia

Background and objective: There are no recent data on the prevalence of drug-resistant tuberculosis (DR TB) in Cambodia. We aim to describe TB drug resistance amongst adults with pulmonary and extra-pulmonary TB and human immunodeficiency virus (HIV) co-infection in a national referral hospital in Phnom Penh, Cambodia. Design: Between 22 November 2007 and 30 November 2009, clinical specimens from HIV-infected patients suspected of having TB underwent routine microscopy, Mycobacterium tuberculosis culture, and drug susceptibility testing. Laboratory and clinical data were collected for patients with positive M. tuberculosis cultures. Results: M. tuberculosis was cultured from 236 HIV-infected patients. Resistance to any first-line TB drug occurred in 34.7% of patients; 8.1% had multidrug resistant tuberculosis (MDR TB). The proportion of MDR TB amongst new patients and previously treated patients was 3.7 and 28.9%, respectively (p<0.001). The diagnosis of MDR TB was made after death in 15.8% of patients; in total 26.3% of patients with MDR TB died. The diagnosis of TB was established by culture of extra-pulmonary specimens in 23.6% of cases. Conclusions: There is significant resistance to first-line TB drugs amongst new and previously treated TB–HIV co-infected patients in Phnom Penh. These data suggest that the prevalence of DR TB in Cambodia may be higher than previously recognised, particularly amongst HIV-infected patients. Additional prevalence studies are needed. This study also illustrates the feasibility and utility of analysis of non-respiratory specimens in the diagnosis of TB, even in low-resource settings, and suggests that extra-pulmonary specimens should be included in TB diagnostic algorithms

Sub-national variation in measles vaccine coverage and outbreak risk: a case study from a 2010 outbreak in Malawi

Abstract Background Despite progress towards increasing global vaccination coverage, measles continues to be one of the leading, preventable causes of death among children worldwide. Whether and how to target sub-national areas for vaccination campaigns continues to remain a question. We analyzed three metrics for prioritizing target areas: vaccination coverage, susceptible birth cohort, and the effective reproductive ratio (RE) in the context of the 2010 measles epidemic in Malawi. Methods Using case-based surveillance data from the 2010 measles outbreak in Malawi, we estimated vaccination coverage from the proportion of cases reporting with a history of prior vaccination at the district and health facility catchment scale. Health facility catchments were defined as the set of locations closer to a given health facility than to any other. We combined these estimates with regional birth rates to estimate the size of the annual susceptible birth cohort. We also estimated the effective reproductive ratio, RE, at the health facility polygon scale based on the observed rate of exponential increase of the epidemic. We combined these estimates to identify spatial regions that would be of high priority for supplemental vaccination activities. Results The estimated vaccination coverage across all districts was 84%, but ranged from 61 to 99%. We found that 8 districts and 354 health facility catchments had estimated vaccination coverage below 80%. Areas that had highest birth cohort size were frequently large urban centers that had high vaccination coverage. The estimated RE ranged between 1 and 2.56. The ranking of districts and health facility catchments as priority areas varied depending on the measure used. Conclusions Each metric for prioritization may result in discrete target areas for vaccination campaigns; thus, there are tradeoffs to choosing one metric over another. However, in some cases, certain areas may be prioritized by all three metrics. These areas should be treated with particular concern. Furthermore, the spatial scale at which each metric is calculated impacts the resulting prioritization and should also be considered when prioritizing areas for vaccination campaigns. These methods may be used to allocate effort for prophylactic campaigns or to prioritize response for outbreak response vaccination

Nontuberculous Mycobacteria Infections at a Provincial Reference Hospital, Cambodia

International audiencePrevalence of nontuberculous mycobacteria (NTM) disease is poorly documented in countries with high prevalence of tuberculosis (TB). We describe prevalence, risk factors, and TB program implications for NTM isolates and disease in Cambodia. A prospective cohort of 1,183 patients with presumptive TB underwent epidemiologic, clinical, radiologic, and microbiologic evaluation, including \textgreater12-months of follow-up for patients with NTM isolates. Prevalence of NTM isolates was 10.8% and of disease was 0.9%; 217 (18.3%) patients had TB. Of 197 smear-positive patients, 171 (86.8%) had TB confirmed (167 by culture and 4 by Xpert MTB/RIF assay only) and 11 (5.6%) had NTM isolates. HIV infection and past TB were independently associated with having NTM isolates. Improved detection of NTM isolates in Cambodia might require more systematic use of mycobacterial culture and the use of Xpert MTB/RIF to confirm smear-positive TB cases, especially in patients with HIV infection or a history of TB

Lessons and Challenges for Measles Control from Unexpected Large Outbreak, Malawi

Despite high reported coverage for routine and supplementar

Measles cases, deaths, attack rates , and case fatality ratios by age group, reported in Malawi between week 1 and week 52 of 2010 and in Katanga Province between week 23 of 2010 and week 52 of 2011.

<p>Percent values in parentheses are percent of all cases or deaths that are in that age group. Population figures for Malawi are a projection from estimates of the 2008 Population and Housing Census <a href="http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.1001544#pmed.1001544-National1" target="_blank">[24]</a>; population figures for Katanga are a projection from estimates of the 2007 Demographic and Health Survey <a href="http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.1001544#pmed.1001544-Democratic1" target="_blank">[25]</a>.</p>a<p>Data are from only the 28 health zones of Katanga where surveillance was reinforced.</p