Cockroaches are persistent and troublesome pests of homes, restaurants, hospitals, warehouses, offices, and other structures with food handling areas. These insects contaminate food and utensils, destroy fabric and paper products, and impart stain and odor to surfaces they contact. They are amazing creatures, though, as they are able not only to regrow their lost legs and limbs in just 18 weeks, but that those body parts also grow in size with each subsequent molt.
The medical importance of cockroaches is much greater than generally realized as they have been shown to carry diverse pathogenic and non-pathogenic bacterial flora, different protozoa, pathogenic helminths, fungi, and viruses. Like any biting or walking insects, such as bedbugs cockroaches can be very good transporters and thus can participate in spreading molds. It was reported that 98% of cockroaches found in medical facilities could carry pathogens on their integuments or digestive tracts. The mite (Pimeliaphilus cunliffei) is a parasite of cockroaches. It feeds on live individuals and has been linked to bites of humans living in households with cockroach infestations.6,7,9
Cockroaches are universally loathed. One of the primary reasons is because they are associated with any place where there are biological waste products such as sewers, septic tanks, garbage cans, chicken houses, and animal cages. Their attraction to human and animal feces, rotting food, secretions from corpses, sputum, pus, and the like gives them a well-earned “disgust factor” among the general public. All these moist, organic habitats contain staggering amounts of bacteria, protozoa, amoebae, fungi, and other microbial material.3
Cockroaches belong to the insect order Dictyoptera. Young and immature cockroaches resemble adults, that is, they undergo gradual metamorphosis. Adults of male species have wings, although many species do not fly.
Although there are 70 described species of cockroaches in the United States, and over 4,000 worldwide, only a few are major pests. However, although the vast majority of cockroaches are presumed to be medically harmless, it is well to keep in mind that, should any of these change their habits and become followers of man, they too may become as potentially dangerous as the known domiciliary species.
Occasionally species that usually occur outdoors invade buildings. Domiciliary cockroaches include approximately 25 species from the families Blattellidae, Blattidae and Blaberidae. Two species, German cockroach (Blattella germanica) and American cockroach (Periplaneta americana) predominate in temperate and tropical areas, respectively, and have been the focus of allergy research.
Microbes are an essential influence in the nutrition, ecology, and evolution of all cockroaches. The main source of nourishment for cockroaches in mines and sewers, for example, is human feces, which can be 80% bacterial. German cockroaches have been observed feeding on mouth secretions of corpses riddled with lung disease; these secretions were almost 100% infectious bacteria.3
The makeup of the microbial population of the American cockroach gut, long the subject of numerous investigations, has been shown to include a variety of microorganisms, bacteria, protozoa, and nematodes. Cockroaches, especially species that come in contact with feces like German cockroaches may transmit bacteria responsible for food poisoning. Cockroaches act as a mechanical vector in transmitting Salmonella, Shigella, and Cryptosporidium parvum bacteria that cause diarrheal diseases.
High resistance rates of bacteria were observed against some of the antibiotics. Among antibiotics tested for all isolates, more than half of isolates were found to be resistant to cotrimoxazole, and especially Gram-positive bacterial isolates have shown complete resistance to penicillin.16
Antibiotic-resistant strains of Klebsiella pneumoniae bacteria that cause pneumonia has been found in patients and cockroaches in hospitals. Multi-drug resistance with resistance to Ampicillin (13.7%-100%), Chloramphenicol (14.3%-71.4%), Tetracycline (14.3%-73.3%), and Trimethoprim-Sulfamethoxazole (14.3%-57.1%) was found in gram-positive and gram-negative bacteria. In addition, evidence suggests that cockroaches spread typhoid, dysentery, and leprosy organisms.2
At least 32 species of bacteria have been isolated from cockroaches in domestic environments. A total of 174 bacterial isolates were isolated from 39 German cockroach specimens in the hospital environment.9 These may include:
- Aeromonas species cause wound and other infections, diarrhea.
- Alcaligenes faecalis causes of gastroenteritis, urinary tract infections.
- Bacillus cereus causes food poisoning.
- Bacillus subtilis causes conjunctivitis.
- Campylobacter jejuni causes enteritis.
- Clostridium perfringens causes food poisoning, gas gangrene.
- Enterobacter species cause bacteremia (temporary presence of bacteria in the blood, which is commonly followed by the development of various infections, including abscesses).
- Enterococcus species cause urinary tract and wound infections. Cockroaches in the confined swine production environment may act as vectors and/or reservoirs of antibiotic-resistant enterococci.
- Escherichia coli causes diarrhea, wound infections.
- Helicobacter hepaticus, animal and human pathogen associated with inflammation of the gallbladder (cholecystitis), gallbladder stones and gallbladder cancer.14,15
- Klebsiella species cause pneumonia and urinary tract infections.
- Mycobacterium leprae causes leprosy.
- Morganella morganii causes wound infections.
- Nocardia species cause actinomycetoma (chronic infection of the skin and underlying tissues).
- Oligella urethralis may cause bacteremia, septic arthritis that mimics gonococcal arthritis, and peritonitis.4
- Pantoea species cause wound infections.
- Proteus rettgeri causes wound infections.
- Proteus vulgaris causes wound infections.
- Proteus mirabilis causes wound infections, gastroenteritis.
- Pseudomonas species cause respiratory infections, gastroenteritis.
- Salmonella cause gastroenteritis, food poisoning
- Salmonella typhi causes typhoid.
- Salmonella pyogenes causes pneumonia.
- Serratia species cause food poisoning.
- Shigella dysenteriae causes dysentery.
- Sphyngobacterium species cause sepsis (presence in the blood or other tissues of pathogenic microorganisms or their toxins).
- Staphylococcus aureus causes wound infections, skin infections, infections of internal organs.
- Staphylococcus epidermidis causes wound infections.
- Streptococcus faecalis and other species cause pneumonia.
- Chlamydia trachomatis causes trachoma, infectious eye disease, the leading cause of the world’s infectious blindness. Globally, 41 million people suffer from active infection, and nearly 8 million people are visually impaired as a result of this disease.
- Yersinia pestis (isolated from oriental cockroach), causes plague.
Cockroaches also have been found harboring eggs of seven species of helminths (hookworm, giant human roundworm, pinworm, tapeworm, and whipworm). The helminths harbored by cockroaches include:
- Ascaris lumbricoides (giant roundworm of humans)
- Trichuris trichiura (human whipworm)
- Taenia species (tapeworms)
- Strongyloides-like parasites (roundworms)8
Cockroaches harbor at least 17 fungal species of medical importance (Candida, Rhizopus, Mucor, Alternaria and Aspergillus), three protozoan species, and two strains of poliomyelitis virus. Australian, American, and Madeira cockroaches become infected with the protozoan Toxoplasma gondii, the causative agent of toxoplasmosis, after feeding on feces of infected cats. This suggests the possibility of cockroach involvement in the maintenance and dissemination of this parasite, which infects humans and other animals.5 Besides cockroaches, flies and earthworms are experimentally-proven to transport or hosts for T. gondii which is capable of causing or aggravating human diseases.17
Cockroaches may also be regarded as vectors for multiflagellated protozoal parasites. They carry in their gut Lophomonas blattarum, a species of multi flagellated protozoa the viable cysts of which can enter into the human body by inhalation or ingestion of material contaminated by cockroach feces. These can cause bronchopulmonary infection (bronchopulmonary lophomoniasis) and respiratory symptoms, which may include progressive headache, fever, dizziness, ear pain, green and sticky nasal discharge, and sneezing. Infections with this parasite do not respond to antibiotic therapy. This protozoa can also cause sinus infections, urinary infections, and intrauterine infections.
Association Between Low Income & Cockroaches
Cockroaches repeatedly have been recognized as a common source of indoor allergens. In the United States, 63% of homes have detectable levels of cockroach allergens. Low-income households and older homes are also among the factors frequently associated with U.S. residences having high concentrations of mouse and cockroach allergens.
In some communities, more than 40% of the middle-class suburban population lives in homes with elevated levels of cockroach allergens.13 They flourish where sufficient food, moisture, and warmth are available (kitchens, bathrooms, and similar areas), and they can survive low humidity better than dust mites and, unlike mites, search actively for the water they need to survive. Allergenic proteins from cockroaches and mites are associated with particles that are 5 microns (μm) or greater and become airborne only when settled dust is disturbed.
Cockroach allergy is an important health problem associated with the development of asthma, as a consequence of chronic exposure to low levels of allergens in susceptible individuals. At least eleven proteins isolated from German and American cockroaches can cause allergic reactions and contribute to asthma in humans. The allergens are heat-stable and persistent in the environment even after the insect death. Cockroach allergen sensitization is one of the greatest risk factors for increased asthma-related poor health among the low-income population in the United States (referred to as the inner-city asthma problem in the US).10
Cockroach allergy is associated with atopic eczema (atopic dermatitis), a chronic inflammatory skin condition characterized by a severe itch and red rash that favors the skin creases such as folds of elbows or behind the knees. Studies have reported that more children with atopic eczema who attended as inpatients for their condition subsequently developed asthma.11 Allergy to cockroach allergens increases with age. The underlying cause is an enzyme called protease produced by coackroaches that activates a type of skin receptors (PAR-2) which play an important role in inflammation. PAR-2-activated conditions include rheumatic arthritis, tumor progression, allergic reaction, and pain.12
Cockroaches can be found in aircraft, especially aircraft that spend time on the ground in tropical environments. Dust mites and cockroaches are the only arthropods that might habitually infest aircraft and possibly become sources of allergens in the cabin environment.
Cockroaches in confined swine operations carry a large antibiotic-resistant and potentially virulent enterococcal bacteria.
- Yiu H. Hui – Handbook Of Food Science, Technology, And Engineering
- Pat O’connor-marer – Residential, Industrial, And Institutional Pest Control
- William J. Bell, Louis Marcus Roth, Christine A. Nalepa – Cockroaches: Ecology, Behavior, And Natural History
- Robert S. Porter – Merck Manuals: Oligella Infections
- Gary Richard Mullen, Gary Mullen, Lance Durden – Medical And Veterinary Entomology
- William H. Robinson – Handbook Of Urban Insects And Arachnids
- Anna Pomés, L. Karla Arruda – Investigating Cockroach Allergens: Aiming To Improve Diagnosis And Treatment Of Cockroach Allergic Patients
- Haji Hamu, Serkadis Debalke, Endalew Zemene, Belay Birlie, Zeleke Mekonnen, Delenasaw Yewhalaw – Isolation Of Intestinal Parasites Of Public Health Importance From Cockroaches (Blattella Germanica) In Jimma Town, Southwestern Ethiopia
- Taha Menasria, Fatima Moussa, Souad El-Hamza, Samir Tine, Rochdi Megri, Haroun Chenchouni – Bacterial Load Of German Cockroach (Blattella Germanica) Found In Hospital Environment
- Christiane Hilger, Annette Kuehn, Monika Raulf, Thilo Jakob – Cockroach, Tick, Storage Mite And Other Arthropod Allergies: Where Do We Stand With Molecular Allergy Diagnostics?
- Atopic Eczema in Children: Management of Atopic Eczema in Children from Birth up to the Age of 12 Years. NICE Clinical Guidelines, No. 57.
- Carstens E, Akiyama T – Itch: Mechanisms and Treatment
- U.S. Department of Health and Human Services , Office of the Surgeon General – The Surgeon General’s Call To Action To Promote Healthy Homes
- Mobley HLT, Mendz GL, Hazell SL – Helicobacter Pylori: Physiology And Genetics
- Tahereh Falsafi, Mohaddese Mahboubi – Helicobacter Hepaticus, A New Pathogenic Species Of The Helicobacter Genus: Similarities And Differences With H. Pylori
- Setegn Eshetie, Mengistu Endris, Kahsay Huruy, Dagnachew Muluye, Tigist Feleke, Fisha G/Silassie, Getenet Ayalew, Raja Nagappan – Cockroaches as a Source of High Bacterial Pathogens with Multidrug Resistant Strains in Gondar Town, Ethiopia – Biomed Res Int. 2016; 2016: 2825056
- Chao Yan, Li-Jun Liang, Kui-Yang Zheng, Xing-Quan Zhu – Impact Of Environmental Factors On The Emergence, Transmission And Distribution Of Toxoplasma Gondii – Parasites & Vectors20169:137 DOI: 10.1186/s13071-016-1432-6