Random Nature #172

Chronic Ear Infections:  In recent years, Australia has been struggling with the following problem.

The Northern Territory has the highest rates of ear disease in the world.

Two-thirds of all Indigenous children there have hearing problems by the time they start school.

About half of them will end up with permanently perforated ear drums as a result of chronic ear infections.

The two bacteria that most commonly cause pneumonia bear much of the blame, Streptococcus pneumoniae and the confusingly named Haemophilus influenzae (it was discovered during and mistakenly blamed for causing a flu pandemic in the 1890s).  Both can cause a number of maladies, including otitis media, "inflammation of the middle ear." 

Dr Andrews says tests on even the tiniest babies shows the bacteria appear in their ears and noses in the very first weeks of life.

"Shortly after they're born, within a few weeks they'll start to carry the bacteria and so you get a build-up behind the ear drum and you get a perforation," he said.

"If an individual child gets that and nothing else happens, that can be resolved and recover and everybody goes on quite well.

"But if you get it and you get it again, you get it again, you can finish up with what's called chronic suppurative otitis media, so it's basically a hole in your ear drum permanently."      

Poverty plays a part--but only a part--in the high rate of infection.  Australian health authorities are now testing giving a pneumococcal vaccine (PneuMum) to pregnant mothers in hopes that they will pass along resistance to their children in womb and/or while breastfeeding.  This strategy has proven to work with some vaccines.  From this link...

The fetus passive immunization from the pregnant woman's vaccination was recognized in 1879 when Bukhardt demonstrated the protection of children whose mothers had been vaccinated against smallpox. Some vaccines commercially available are considered safe when administered during pregnancy, and provide an increase in antibody levels for the following pathogens: diphtheria, tetanus toxoids, mumps, meningococcus and Hib.

Hib is Haemophilus influenzae type b. 

A Different BT:  Bluetongue disease is a viral infection that strikes ruminants.     

BT primarily affects sheep, and susceptibility to disease varies with breed. European breeds are more susceptible to infection with BT virus. White-tailed deer and pronghorn are very susceptible to the BT virus, and may be more severely affected than sheep. Cattle, goats, North American elk, elephants, and dromedary camels may become infected with the BT virus, but infection is inapparent and they potentially serve as reservoirs.

Well, inapparent or mild in cattle, elk, etc.  In sheep, bluetongue can cause the following.

Eye and nasal discharges

Drooling as a result of ulcerations in the mouth

High body temperature

Swelling of the mouth, head and neck

Lameness

Haemorrhages into or under the skin

Inflammation at the junction of the skin and the horn of the foot – the coronary band

Respiratory problems – difficulty with breathing and nasal discharge

A blue tongue is rarely a clinical sign of infection

Deaths of sheep in a flock may reach as high as 70 per cent. Animals that survive the disease can lose condition with a reduction in meat and wool production

Infected animals aren't contagious; the 24 strains of the virus are spread by various species of midges (small, bloodsucking flies that are sometimes called gnats).  Cattle can act as an important reservoir of the disease.  However, sometimes the disease strikes when local animals are healthy and the midges have frozen out for the winter.  The assumption has been that the virus can overwinter in midge larvae, but evidence of this has been lacking.  There's also been speculation that the virus can be transported in horse manure.

Events this past winter have provided researchers with another possibility.

According to the UK's Institute for Animal Health in Pirbright, there is a "distinct possibility" that the virus might overwinter by infecting unborn calves. In January this year, pregnant cows which had recovered from bluetongue infections and no longer carried the virus were exported from Holland to Northern Ireland, which is free of bluetongue. In February, three of these gave birth to calves which carried the virus. When biting midges reappear in the spring, such calves would become a fresh source of the bluetongue virus for them. As a result, the institute suggests additional controls be targeted at newborn animals.

Intriguingly, the only bluetongue virus ever seen to cross the placenta of infected mothers to infect their fetuses was a laboratory-adapted strain used in experiments in sheep in the 1970s. This raises the possibility that Europe's BTV8 strain might be descended from a research strain or a vaccine.

Maybe.  Until its recent appearance in Europe, BTV8 was only known in Africa, Southeast Asia, and the Dominican Republic.  Other strains are a problem here in the U.S.

Bluetongue was first recognized in South Africa in the late 1800s, but it was not until the early 1900s that it was described in detail. The disease was reported in Cyprus in 1943 and subsequently in Israel, Turkey, Spain, Portugal, Pakistan, India, and the United States during the 1950s. In the United States, the disease is most prevalent in the southern and southwestern States.

...

For more than 25 years, the presence of bluetongue viruses in the United States has blocked the export of U.S. cattle, sheep, and goats to many major world markets, including Australia, New Zealand, and the European Union. Canada accepts U.S. cattle, but requires rigorous testing before the animals may cross the border.

Last year, there was an outbreak in sheep as far north as Montana.