Download the Free Unbound MEDLINE PubMed App to your smartphone or tablet.
Available for iPhone, iPad, iPod touch, and Android.
Infectious disease AND Bites, insect [keywords]
- Bed bugs: clinical relevance and control options. [Journal Article, Review]
- Clin Microbiol Rev 2012 Jan; 25(1):164-92.
Since the late 1990s, bed bugs of the species Cimex lectularius and Cimex hemipterus have undergone a worldwide resurgence. These bed bugs are blood-sucking insects that readily bite humans. Cutaneous reactions may occur and can start out as small macular lesions that can develop into distinctive wheals of around 5 cm in diameter, which are accompanied by intense itching. Occasionally, bullous eruptions may result. If bed bugs are numerous, the patient can present with widespread urticaria or eythematous rashes. Often, bites occur in lines along the limbs. Over 40 pathogens have been detected in bed bugs, but there is no definitive evidence that they transmit any disease-causing organisms to humans. Anemia may result when bed bugs are numerous, and their allergens can trigger asthmatic reactions. The misuse of chemicals and other technologies for controlling bed bugs has the potential to have a deleterious impact on human health, while the insect itself can be the cause of significant psychological trauma. The control of bed bugs is challenging and should encompass a multidisciplinary approach utilizing nonchemical means of control and the judicious use of insecticides. For accommodation providers, risk management procedures should be implemented to reduce the potential of bed bug infestations.
- Assessment and monitoring of onchocerciasis in Latin America. [Journal Article, Research Support, Non-U.S. Gov't, Review]
- Adv Parasitol 2011.:175-226.
Onchocerciasis has historically been one of the leading causes of infectious blindness worldwide. It is endemic to tropical regions both in Africa and Latin America and in the Yemen. In Latin America, it is found in 13 foci located in 6 different countries. The epidemiologically most important focus of onchocerciasis in the Americas is located in a region spanning the border between Guatemala and Mexico. However, the Amazonian focus straddling the border of Venezuela and Brazil is larger in overall area because the Yanomami populations are scattered over a very large geographical region. Onchocerciasis is caused by infection with the filarial parasite Onchocerca volvulus. The infection is spread through the bites of an insect vector, black flies of the genus Simulium. In Africa, the major vectors are members of the S. damnosum complex, while numerous species serve as vectors of the parasite in Latin America. Latin America has had a long history of attempts to control onchocerciasis, stretching back almost 100 years. The earliest programmes used a strategy of surgical removal of the adult parasites from affected individuals. However, because many of the adult parasites lodge in undetectable and inaccessible areas of the body, the overall effect of this strategy on the prevalence of infection was relatively minor. In 1988, a new drug, ivermectin, was introduced that effectively killed the larval stage (microfilaria) of the parasite in infected humans. As the microfilaria is both the stage that is transmitted by the vector fly and the cause of most of the pathologies associated with the infection, ivermectin opened up a new strategy for the control of onchocerciasis. Concurrent with the use of ivermectin for the treatment of onchocerciasis, a number of sensitive new diagnostic tools were developed (both serological and nucleic acid based) that provided the efficiency, sensitivity and specificity necessary to monitor the decline and eventual elimination of onchocerciasis as a result of successful control. As a result of these advances, a strategy for the elimination of onchocerciasis was developed, based upon mass distribution of ivermectin to afflicted communities for periods lasting long enough to ensure that the parasite population was placed on the road to local elimination. This strategy has been applied for the past decade to the foci in Latin America by a programme overseen by the Onchocerciasis Elimination Program for the Americas (OEPA). The efforts spearheaded by OEPA have been very successful, eliminating ocular disease caused by O. volvulus, and eliminating and interrupting transmission of the parasite in 8 of the 13 foci in the region. As onchocerciasis approaches elimination in Latin America, several questions still need to be addressed. These include defining an acceptable upper limit for transmission in areas in which transmission is thought to have been suppressed (e.g. what is the maximum value for the upper bound of the 95% confidence interval for transmission rates in areas where transmission is no longer detectable), how to develop strategies for conducting surveillance for recrudescence of infection in areas in which transmission is thought to be interrupted and how to address the problem in areas where the mass distribution of ivermectin seems to be unable to completely eliminate the infection.
- Sahel, savana, riverine and urban malaria in West Africa: Similar control policies with different outcomes. [Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't]
- Acta Trop 2012 Mar; 121(3):166-74.
The study sites for the West African ICEMR are in three countries (The Gambia, Senegal, Mali) and are located within 750 km of each other. In addition, the National Malaria Control Programmes of these countries have virtually identical policies: (1) Artemisinin Combination Therapies (ACTs) for the treatment of symptomatic Plasmodium falciparum infection, (2) Long-Lasting Insecticide-treated bed Nets (LLINs) to reduce the Entomololgic Inoculation Rate (EIR), and (3) sulfadoxine-pyrimethamine for the Intermittent Preventive Treatment of malaria during pregnancy (IPTp). However, the prevalence of P. falciparum malaria and the status of malaria control vary markedly across the four sites with differences in the duration of the transmission season (from 4-5 to 10-11 months), the intensity of transmission (with EIRs from unmeasurably low to 4-5 per person per month), multiplicity of infection (from a mean of 1.0 to means of 2-5) and the status of malaria control (from areas which have virtually no control to areas that are at the threshold of malaria elimination). The most important priority is the need to obtain comparable data on the population-based prevalence, incidence and transmission of malaria before new candidate interventions or combinations of interventions are introduced for malaria control.
- The abundance and host-seeking behavior of culicine species (Diptera: Culicidae) and Anopheles sinensis in Yongcheng city, People's Republic of China. [Journal Article, Research Support, Non-U.S. Gov't]
- Parasit Vectors 2011.:221.
The knowledge of mosquito species diversity and the level of anthropophily exhibited by each species in a region are of great importance to the integrated vector control. Culicine species are the primary vectors of Japanese encephalitis (JE) virus and filariasis in China. Anopheles sinensis plays a major role in the maintenance of Plasmodium vivax malaria transmission in China. The goal of this study was to compare the abundance and host-seeking behavior of culicine species and An. sinensis in Yongcheng city, a representative region of P. vivax malaria. Specifically, we wished to determine the relative attractiveness of different animal baits versus human bait to culicine species and An. sinensis.Culex tritaeniorhynchus was the most prevalent mosquito species and An. sinensis was the sole potential vector of P. vivax malaria in Yongcheng city. There were significant differences (P < 0.01) in the abundance of both An. sinensis and Cx. tritaeniorhynchus collected in distinct baited traps. The relative attractiveness of animal versus human bait was similar towards both An. sinensis and Cx. tritaeniorhynchus. The ranking derived from the mean number of mosquitoes per bait indicated that pigs, goats and calves frequently attracted more mosquitoes than the other hosts tested (dogs, humans, and chickens). These trends were similar across all capture nights at three distinct villages. The human blood index (HBI) of female An. sinensis was 2.94% when computed with mixed meals while 3.70% computed with only the single meal. 19:00~21:00 was the primary peak of host-seeking female An. sinensis while 4:00~5:00 was the smaller peak at night. There was significant correlation between the density of female An. sinensis and the average relative humidity (P < 0.05) in Wangshanzhuang village.Pigs, goats and calves were more attractive to An. sinensis and Cx. tritaeniorhynchus than dogs, humans, and chickens. Female An. sinensis host-seeking activity mainly occurred from 19:00 to 21:00. Thus, we propose that future vector control against An. sinensis and Cx. tritaeniorhynchus in the areas along the Huang-Huai River of central China should target the interface of human activity with domestic animals and adopt before human hosts go to bed at night.
- Adequate wound care and use of bed nets as protective factors against Buruli Ulcer: results from a case control study in Cameroon. [Journal Article, Research Support, Non-U.S. Gov't]
- PLoS Negl Trop Dis 2011 Nov; 5(11):e1392.
Buruli ulcer is an infectious disease involving the skin, caused by Mycobacterium ulcerans. Its exact transmission mechanism remains unknown. Several arguments indicate a possible role for insects in its transmission. A previous case-control study in the Nyong valley region in central Cameroon showed an unexpected association between bed net use and protection against Buruli ulcer. We investigated whether this association persisted in a newly discovered endemic Buruli ulcer focus in Bankim, northwestern Cameroon.We conducted a case-control study on 77 Buruli ulcer cases and 153 age-, gender- and village-matched controls. Participants were interviewed about their activities and habits. Multivariate conditional logistic regression analysis identified systematic use of a bed net (Odds-Ratio (OR) = 0.4, 95% Confidence Interval [95%CI] = [0.2-0.9], p-value (p) = 0.04), cleansing wounds with soap (OR [95%CI] = 0.1 [0.03-0.3], p<0.0001) and growing cassava (OR [95%CI] = 0.3 [0.2-0.7], p = 0.005) as independent protective factors. Independent risk factors were bathing in the Mbam River (OR [95%CI] = 6.9 [1.4-35], p = 0.02) and reporting scratch lesions after insect bites (OR [95%CI] = 2.7 [1.4-5.4], p = 0.004). The proportion of cases that could be prevented by systematic bed net use was 32%, and by adequate wound care was 34%.Our study confirms that two previously identified factors, adequate wound care and bed net use, significantly decreased the risk of Buruli ulcer. These associations withstand generalization to different geographic, climatic and epidemiologic settings. Involvement of insects in the household environment, and the relationship between wound hygiene and M. ulcerans infection should now be investigated.
- Predicting the effect of climate change on African trypanosomiasis: integrating epidemiology with parasite and vector biology. [Journal Article]
- J R Soc Interface 2012 May 7; 9(70):817-30.
Climate warming over the next century is expected to have a large impact on the interactions between pathogens and their animal and human hosts. Vector-borne diseases are particularly sensitive to warming because temperature changes can alter vector development rates, shift their geographical distribution and alter transmission dynamics. For this reason, African trypanosomiasis (sleeping sickness), a vector-borne disease of humans and animals, was recently identified as one of the 12 infectious diseases likely to spread owing to climate change. We combine a variety of direct effects of temperature on vector ecology, vector biology and vector-parasite interactions via a disease transmission model and extrapolate the potential compounding effects of projected warming on the epidemiology of African trypanosomiasis. The model predicts that epidemics can occur when mean temperatures are between 20.7°C and 26.1°C. Our model does not predict a large-range expansion, but rather a large shift of up to 60 per cent in the geographical extent of the range. The model also predicts that 46-77 million additional people may be at risk of exposure by 2090. Future research could expand our analysis to include other environmental factors that influence tsetse populations and disease transmission such as humidity, as well as changes to human, livestock and wildlife distributions. The modelling approach presented here provides a framework for using the climate-sensitive aspects of vector and pathogen biology to predict changes in disease prevalence and risk owing to climate change.
- The seroprevalence of Crimean-Congo haemorrhagic fever among inhabitants living in the endemic regions of Western Anatolia. [Journal Article, Research Support, Non-U.S. Gov't]
- Scand J Infect Dis 2012 Apr; 44(4):276-81.
In Turkey, Crimean-Congo haemorrhagic fever (CCHF) is seen particularly in the north-eastern part of Anatolia. Aydin was thought to be a non-endemic area, however the first case was reported from Aydin in 2006 and a total of 39 cases were reported between 2006 and 2010.Four hundred and twenty-nine volunteers from 3 endemic regions of Aydin were enrolled in this study. We determined the IgG seropositivity against the virus by enzyme-linked immunosorbent assay (ELISA) method.IgG seropositivity in the study group was found to be 19.6% (n = 84). Chi-squared automatic interaction detector (CHAID) analysis was performed and a significant relationship between IgG seropositivity and tick-bite was found. The IgG seropositivity rate was 13% in cases without a history of tick-bite, while it was 41.1% in those with a tick-bite history (p < 0.001). In cases without a history of tick-bite (n = 339), the most important factor related to seropositivity was cattle-dealing. The seropositivity rate was higher in women than in men in the group dealing with cattle without a history of tick-bite (p = 0.013). In cases with a tick-bite history, the most important factor related to IgG seropositivity was age; the rate was 81% in cases younger than 34 y old, while it was 29% in cases older than 34 y.This study indicates that people suffering from the disease did not ask for any professional healthcare or that the healthcare providers could not diagnose these cases.
- Transmission parameters of vector-borne infections. [Journal Article, Review]
- Med Mal Infect 2011 Nov; 41(11):588-93.
Vector-borne infections are those for which the agent (virus, bacteria, or parasite) is transmitted from an infected host (animal or human) to another by a hematophagous arthropod (mosquito, tick, lice, and flea). Two parameters quantify the dynamics of a vector-borne infection: (1) the basic reproductive number (R(0)) that is the mean number of secondary infections transmitted from an infectious host by the bite of the vector and (2) the generation interval that explores the speed of occurrence of secondary cases transmitted by the vector from an infectious case. In a population in which some individuals are immune, the parameter of interest is the net reproduction number (R) function of R(0) and the proportion of those immune. For vector-borne infectious agents, R(0) is determined by the number of vectors in contact with a given individual (m), the number of a given vector bites/day on individuals (a), the daily survival rate of the vector (p), the duration of the pathogenic agent's development cycle in the vector (n), the proportion of infected vectors that are really infectious (vector competence) (b), the probability of agent transmission from a viremic individual to the vector for one bite (c) and the host's infectiousness clearance rate (r) with R(0)=(m. a(2). p(n)/-lnp). b. c/r. These parameters are related to geographic and climatic conditions and cannot, therefore, be extrapolated from one situation to another.
- [Insect-borne diseases and insect bites in Finland]. [English Abstract, Journal Article, Review]
- Duodecim 2011; 127(13):1393-400.
Clinically significant endemic, arthropod-borne infectious diseases in Finland include Lyme disease, tick-borne encephalitis, tularemia and Karelian fever. The diagnosis of early borreliosis or tularemia is clinical and the treatment is initiated already before the results of eventual blood tests. The diagnosis of late stage borreliosis, tick-borne encephalitis or Karelian fever is confirmed mainly with serologic tests. The clinical significance of endemic anaplasmosis, Rickettsia helvetica, Inkoo and Uukuniemi viruses as well as anthropod-borne bunyaviruses and bartonelloses is either minor or remains open.
- Kissing bugs. The vectors of Chagas. [Journal Article, Research Support, N.I.H., Extramural, Research Support, U.S. Gov't, Non-P.H.S.]
- Adv Parasitol 2011.:169-92.
A complete picture of Chagas disease requires an appreciation of the many species of kissing bugs and their role in transmitting this disease to humans and other mammals. This chapter provides an overview of the taxonomy of the major species of kissing bugs and their evolution. Knowledge of systematics and biological kinship of these insects may contribute to novel and useful measures to control the bugs. The biology of kissing bugs, their life cycle, method of feeding and other behaviours contributing to the transmission of Trypanosoma cruzi are explained. We close with a discussion of vector control measures and the allergic complications of kissing bug bites, a feature of particular importance in the United States.