Diseases Spread By Cockroaches

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.

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 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 3,500 worldwide, only a few are major pests. Occasionally species that usually occur outdoors invade buildings.

German cockroach
the German cockroach

(Blatella germanica)

Oriental cockroach

(Blatta orientalis)

American cockroach

(Periplaneta americans)

Asian Cockroach

(Blattella asahinai

Smokybrown cockroach

(Periplaneta fuliginosa)

Photo attribution: Daniel R. Suiter, University of Georgia,

Brownbanded cockroach

(Supella longipalpa)

Photo attribution: Gary Alpert, Harvard University

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, archeans, protozoa, and nematods. Cockroaches, especially species that come in contact with feces like German cockroaches may transmit bacteria responsible for food poisoning. Cockroaches act as mechanical vector in transmitting Salmonella,Shigella, and Cryptosporidium parvum bacteria that cause diarrheal diseases. Antibiotic resistant strain of Klebsiella pneumoniae bacteria that cause pneumonia has been found in patients and cockroaches in a New Delhi hospital. In addition, evidence suggests that cockroaches spread typhoid, disentery, and leprosy organisms.2

Bacteria Carried By Cockroaches

At least 32 species of bacteria have been isolated from cockroaches in domestic environments. These include:

  • Aeromonas spp., cause wound and other infections, diarrhea.
  • Alcaligenes faecalis, causes of gastroenteritis, urinary tract infections.
  • Bacillus cerreus, causes food poisoning.
  • Bacillus subtilis, causes conjunctivitis.
  • Campylobacter jejuni, causes enteritis.
  • Clostridium perfringens, causes food poisoning, gas gangrene.
  • Enterobacter spp., cause bacteremia (temporary presence of bacteria in the blood, which is commonly followed by the development of various infections including abscesses).
  • Enterococcus spp., cause urinary tract and wound infections.
  • Escherichia coli, causes diarrhea, wound infections.
  • Klebsiella spp., cause pneumonia and urinary tract infections.
  • Mycobacterium leprae, causes leprosy.
  • Morganella morganii, causes wound infections
  • Nocardia spp., causes actinomycetoma (chronic infection of the skin and underlying tissues).
  • Oligella urethralis, may cause bacteremia, septic arthritis that mimics gonococcal arthritis, and peritonitis.4
  • Pantoea
  • spp., cause wound infections.
  • Proteus rettgeri, causes wound infections.
  • Proteus vulgaris, causes wound infections.
  • Proteus mirabilis, causes wound infections, gastroenteritis.
  • Pseudomonas spp., cause respiratory infections, gastroenteritis.
  • Salmonella spp., cause gastroenteritis, food poisoning
  • Salmonella typhi, causes typhoid.
  • Salmonella pyogenes, causes pneumonia.
  • Serratia spp., cause food poisoning.
  • Shigella dysenteriae, causes disentery
  • Sphyngobacterium spp., causes sepsis (presence in the blood or other tissues of pathogenic microorganisms or their toxins).
  • Staphylococcus aureus, causes wound infections, skin infections, infections of internal organ.
  • Staphylococcus epidermalis, causes wound infections.
  • Streptococcus faecalis and other species, cause pneumonia.
  • Yersinia pestis (isolated from oriental cockroach), causes plague

Worms, Protozoa, Fungi, and Viruses Carried By Cockroaches

Cockroaches also have been found harboring eggs of seven species of helminths (hookworm, giant human roundworm, pinworm, tapeworm, and whipworm); at least 17 fungal species, three protozoan species, and two strains of polymyelitis 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

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. The cockroach 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


  1. Handbook of food science, technology, and engineering, Volume 2 By Yiu H. Hui
  2. Residential, industrial, and institutional pest control By Pat O'connor-marer
  3. Cockroaches: ecology, behavior, and natural history By William J. Bell, Louis Marcus Roth, Christine A. Nalepa
  4. Oligella Infections,
  5. Medical and Veterinary Entomology By Gary Richard Mullen, Gary Mullen, Lance Durden
  6. Handbook of urban insects and arachnids By William H. Robinson

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